Applied Surface Science (v.349, #C)

Butanol vapor adsorption behavior on active carbons and zeolite crystal by Yuhe Cao; Keliang Wang; Xiaoming Wang; Zhengrong Gu; William Gibbons; Han Vu (1-7).
Butanol is considered a promising, infrastructure-compatible biofuel. Unfortunately, the fermentation pathway for butanol production is restricted by its toxicity to the microbial strains used in the process. Gas stripping technology can efficiently remove butanol from the fermentation broth as it is produced, thereby decreasing its inhibitory effects. Adsorption can then be used to recover butanol from the vapor phase. Active carbon samples and zeolite were investigated for their butanol vapor adsorption capacities. Commercial activated carbon was modified via hydrothermal H2O2 treatment, and the specific surface area and oxygen-containing functional groups of activated carbon were tested before and after treatment. Hydrothermal H2O2 modification increased the surface oxygen content, Brunauer-Emmett-Teller surface area, micropore volume, and total pore volume of active carbon. The adsorption capacities of these active carbon samples were almost three times that of zeolite. However, the un-modified active carbon had the highest adsorption capacity for butanol vapor (259.6 mg g−1), compared to 222.4 mg g−1 after 10% H2O2 hydrothermal treatment. Both modified and un-modified active carbon can be easily regenerated for repeatable adsorption by heating to 150 °C. Therefore, surface oxygen groups significantly reduced the adsorption capacity of active carbons for butanol vapor.
Keywords: Butanol; Biofuel; Gas stripping; Active carbon; H2O2; adsorption;

Low temperature sintering preparation of high-permeability TiO2/Ti composite membrane via facile coating method by Yuqing Lin; Dong Zou; Xianfu Chen; Minghui Qiu; Hideo Kameyama; Yiqun Fan (8-16).
Core–shell structured grains were synthesized for low temperature sintering preparation of TiO2/Ti composite microfiltration (MF) membrane via facile coating method. An optimized facile spraying coating method was proposed to prepare the microfiltration membrane directly onto macroporous support (13 μm), with the aid of sol nanoparticles coating. The spraying coating combined with the substrate heating process was proposed to make the sol into gel in short period of time, so that TiO2 particles could be cross-linked and formed continuous membrane without infiltration. This proposed method could directly prepare the microfiltration membrane onto macroporous substrate, eliminating the step of the intermediate layer fabrication, so that the high-permeability TiO2/Ti composite membrane could be prepared. Moreover, a core–shell structured grain was synthesized to prepare TiO2/Ti composite membrane at lower temperature of 950 °C. The proposed method resolved the problem of thermal expansion mismatch of ceramic membranes and metallic supports for the higher temperature sintering process, so that the defect-free TiO2/Ti composite membranes could be obtained. The prepared TiO2/Ti composite MF membranes showed the most frequent pore size of 380 nm, and a high pure water permeability of 1150 L m−2  h−1  bar−1. The proposed method has a considerable potential in fabricating such integrated ceramic-metallic composite membranes via the facile and low cost route.
Keywords: Ceramic membrane; Metallic support; Spraying coating; Core-shell structure; Low temperature sintering;

Adsorption and desorption of CO on clean and CO pre-covered Mo(1 1 0) have been studied by temperature programmed desorption (TPD), low energy electron diffraction, X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. It was found that adsorption and subsequent desorption of CO from Mo(1 1 0) and CO pre-covered Mo(1 1 0) show large differences in the TPD spectra in the low temperature region from 150 to 400 K. In the case of the pre-covered sample a dramatically increased width to lower temperatures was observed. The increased width at higher CO coverage is argued to result from a distribution of adsorption sites and increased lateral interactions between adsorbed CO molecules.
Keywords: Desorption; CO; Mo(1 1 0); Oxide; TPD;

CO oxidation over fiberglasses with doped Cu-Ce-O catalytic layer prepared by surface combustion synthesis by I.V. Desyatykh; A.A. Vedyagin; I.V. Mishakov; Yu.V. Shubin (21-26).
Surface combustion synthesis was applied as a coating technique to prepare the fiberglass systems with supported oxide layer. Effect of the dopant's nature (Co3O4, Mn3O4) on catalytic activity of the supported copper-ceria samples was studied. Catalyst samples were characterized by various physicochemical methods. Active components exist on surface of support in three different states: large agglomerates; small particles and thin oxide film. The additive is found to be in highly disperse state. Catalytic activity of modified CuO–CeO2 samples has been tested in CO oxidation. It was established that the catalytic performance is to be directly determined by the nature of dopant and the way it interacts with CuO phase.
Keywords: Catalytic filter; Surface combustion synthesis; Oxidation; CO;

In this study, hydrogen-bonding interactions between polyvinylalcohol (PVA) and graphene oxide (GO) were utilized as the driving force to fabricate organic/inorganic PVA nanocomposite films with homogeneous dispersion of GO. The nanomechanical and nanotribological performances of pure PVA and PVA/GO films were investigated by using nanoindentation technique. The results demonstrated that the incorporation of 0.5 wt% GO in PVA gives the highest improvement in nanomechanical and nanotribological properties. Compared to pure PVA, the elastic modulus and hardness of 0.5 wt% GO/PVA were notably increased by 122.8% and 64.5%, respectively. Furthermore, the film showed self-lubrication effect and enhanced anti-scratch performance. TGA study reveals an enhanced maximum decomposing temperature of 68.4 °C with the addition of 0.5 wt% GO in PVA. The stability of hydrogen bonding between PVA and GO accompanied with the formed organic/inorganic assembled lamellar micro-structure of PVA/GO films is the main reason for the distinct improvements in nanomechanical, nanotribological and thermal properties of PVA/GO nanocomposite films.
Keywords: Graphene oxide; Polyvinylalcohol (PVA); Nanocomposite film; Nanomechanical; Nanotribological; Thermal stability;

Fabrication of polyaniline/carboxymethyl cellulose/cellulose nanofibrous mats and their biosensing application by Jiapeng Fu; Zengyuan Pang; Jie Yang; Fenglin Huang; Yibing Cai; Qufu Wei (35-42).
We report a facile approach to synthesizing and immobilizing polyaniline nanorods onto carboxymethyl cellulose (CMC)-modified cellulose nanofibers for their biosensing application. Firstly, the hierarchical PANI/CMC/cellulose nanofibers were fabricated by in situ polymerization of aniline on the CMC-modified cellulose nanofiber. Subsequently, the PANI/CMC/cellulose nanofibrous mat modified with laccase (Lac) was used as biosensor substrate material for the detection of catechol. PANI/CMC/cellulose nanofibers with highly conductive and three dimensional nanostructure were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimum conditions, the Lac/PANI/CMC/cellulose/glassy carbon electrode (GCE) exhibited a fast response time (within 8 s), a linear response range from 0.497 μM to 2.27 mM with a high sensitivity and low detection limit of 0.374 μM (3σ). The developed biosensor also displayed good repeatability, reproducibility as well as selectivity. The results indicated that the composite mat has potential application in enzyme biosensors.
Keywords: Electrospinning; Cellulose; Polyaniline; Laccase; Biosensor; Catechol;

The friction which plays an essential role on normal contact stiffness is usually omitted in existed researches, thus a modified fractal model for normal contact stiffness considering friction is discussed in this paper for calculating normal contact stiffness precisely and reasonably. The model is obtained by introducing a specific coefficient factor into the equation of the normal contact stiffness which is deduced by employing the theory of fractal contact and the definition of stiffness. Through the simulation and comparison with the original model and experiment result, it is clearly concluded that the modified model can reveal the influence of friction on contact area as well as calculate the normal contact stiffness more accurately. Furthermore, the numerical results show that the normal contact stiffness increases with the normal load; it is advantageous to improve the normal contact stiffness of rough surface by adding fractal dimension-D and reducing fractal scaling parameter-G. Also, the friction coefficient decreases with adding D and G and the fractal dimension has a marked impact on the friction coefficient. The presented achievements will help to analyze the performance for surface contact dynamics in the future.
Keywords: Fractal; W-M function; Friction; Normal contact stiffness;

Detailed scanning tunneling microscopy and spectroscopy (STM and STS) studies for the effects of thermal migration and electromigration on the growth of gadolinium–silicide nanomeshes on double-domain Si(1 1 0)-16 × 2 surfaces are presented to identify the driving force for the self-organization of a perfectly ordered silicide nanomesh on Si(1 1 0). STM results clearly show that the anisotropic electromigration effect is crucial for the control of the spatial uniformity of a self-ordered silicide nanomesh on Si(1 1 0). This two-dimensional self-ordering driven by the anisotropic-electromigration-induced growth allows the sizes and positions of crossed nanowires to be precisely controlled within a variation of ±0.2 nm over a mesoscopic area, and it can be straightforwardly applied to other metals (e.g., Au and Ce) to grow a variety of highly regular silicide nanomeshes for the applications as nanoscale interconnects. Moreover, the STS results show that the anisotropic electromigration-induced growth causes the metallic horizontal nanowires to cross over the semiconducting oblique nanowires, which opens the possibility for the atomically precise bottom-up fabrication of well-defined crossbar nanoarchitectures.
Keywords: Nanomeshes; Self-organization; Electromigration; Gadolinium silicides; Si(1 1 0); Scanning tunneling microscopy;

This paper presents a study of the interfacial characteristics in a SWCNT/epoxy nanocomposites system using Molecular dynamics simulations. Interaction energy at the interface of SWCNT and matrix and interfacial shear strength (IFSS) is calculated. Effects of temperature and functionalization with different functional groups (Amide and Phenyl) and their distribution on the interfacial properties of nanocomposites are studied. The Interaction energy is used to calculate the interfacial stiffness in case of Pristine CNT/epoxy system. Pull out simulation of the CNT is performed to characterize the IFSS. The results suggested the existence of attractive interface between CNT and the epoxy for all the cases analyzed. The Interaction energy increases with decrease in temperature and decreases with increase in temperature from the room temperature. Functionalization of CNTs increases the interaction when compared with the pristine one which further increases with degree of functionalization. The IFSS decreases with temperature in case of pristine CNTs and increases with functionalization.
Keywords: Nanocomposites; CNT functionalization; Interaction energy; Pull out; Interface;

Nano-ZnO embedded mixed matrix polyethersulfone (PES) membrane: Influence of nanofiller shape on characterization and fouling resistance by Hamid Rajabi; Negin Ghaemi; Sayed S. Madaeni; Parisa Daraei; Bandar Astinchap; Sirus Zinadini; Sayed Hossein Razavizadeh (66-77).
Two different kinds of nano-ZnO (nanoparticle and nanorod) were synthesized, characterized, and embedded in a PES membrane matrix to investigate the effects of a nanofiller shape on the mixed matrix membrane characteristics and the antifouling capability. The mixed matrix membranes were fabricated by mixing different amounts of nanofillers with dope solution followed by a phase inversion precipitation technique. The effect of the shape of the embedded nanofillers on the morphology and performance of the fabricated membranes was studied in terms of pure water flux, fouling resistance, hydrophilicity, surface, and bulk morphology by means of permeation tests, milk powder solution filtration, water contact angle and porosity measurements, scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques. Water flux of the mixed matrix membranes significantly improved after the addition of both types of ZnO nanofillers due to a higher hydrophilicity and porosity of the prepared membranes. The water contact angle measurements confirmed the increased hydrophilicity of the modified membranes, particularly in the ZnO nanorod mixed membranes. Fouling resistance of the membranes assessed by powder milk solution filtration revealed that 0.1 wt% ZnO nanorod membrane has the best antifouling property. The prepared mixed matrix membranes embedded with 0.1 wt% of both types of ZnO nanofillers showed a remarkable durability and reusability during the filtration tests; however, the best performance came from membrane prepared with ZnO nanorods.
Keywords: Mixed matrix PES membrane; Fouling resistance; Zinc oxide; Nanorod; Nanoparticle;

Room-temperature selective epitaxial growth of CoO (1 1 1) and Co3O4 (1 1 1) thin films with atomic steps by pulsed laser deposition by Akifumi Matsuda; Ryosuke Yamauchi; Daishi Shiojiri; Geng Tan; Satoru Kaneko; Mamoru Yoshimoto (78-82).
Cobalt oxide epitaxial thin films of both rock-salt CoO and spinel Co3O4 were selectively synthesized on atomically stepped α-Al2O3 (0 0 0 1) substrates at room temperature under well-controlled oxygen pressures by pulsed laser deposition. X-ray diffraction and reflection high-energy electron diffraction analyses demonstrated that the CoO and Co3O4 films were grown with phase control and good epitaxial quality at room temperature (20 °C). The CoO (1 1 1) film was obtained in ultra-high vacuum of 1 × 10−8  Torr, while the Co3O4 (1 1 1) film was grown in 1 × 10−2  Torr of O2. X-ray reciprocal space mapping results indicated that the in-plane mismatches of the {1 = 10} planes of CoO (1 1 1) and Co3O4 (1 1 1) films with the substrate were 4.5% and 2.5%, respectively. The films were almost entirely relaxed with ratios of expansion less than ±2%; the films underwent slight elongation along the [1 1 1] axis and shrinkage in the (1 1 1) plane. The surfaces of the as-grown CoO and Co3O4 thin films revealed atomic steps reflective of those on the substrates. Their root-mean-square roughness values were about 0.1 nm indicating suppressed grain growth on the substrates at room temperature. The optical bandgap of the epitaxial CoO (1 1 1) film was estimated to be 2.72 eV accompanied with a broad absorption attributable to non-stoichiometry or d-d transition. The bandgap of the Co3O4 (1 1 1) film was evaluated as 1.42 eV, and also absorption at 1.86 eV was observed. The obtained room-temperature epitaxial growth of CoO and Co3O4 thin films contributes to enhance their catalytic ability and quality of layer-stacking devices in terms of improving surface/interface flatness and specific surface area.
Keywords: Cobalt oxide; Epitaxy; Thin film; Pulsed laser deposition; Room temperature; Atomic steps;

In this study, chitosan coated Mn-doped ZnS quantum dots (CS@ZnS:Mn D-dots) were obtained in aqueous media under ambient pressure. The interaction and illumination damages of CS@ZnS:Mn D-dots with bovine serum albumin (BSA) were studied by means of ultraviolet–visible (UV–vis) and fluorescence (FL) spectra. It was found that the FL of BSA was quenched by CS@ZnS:Mn D-dots. The dominating quenching mechanism of CS@ZnS:Mn D-dots with BSA belongs to dynamic quenching. Hydrophobic interaction plays a major role in the CS@ZnS:Mn–BSA interaction; binding processes are spontaneous. Influencing factors such as illumination time and CS@ZnS:Mn D-dots concentrations were considered. The FL quenching effect of BSA by CS@ZnS:Mn D-dots is enhanced with the increase of illumination time and CS@ZnS:Mn D-dots concentration. The FL enhancement of CS@ZnS:Mn D-dots by BSA under UV illumination was also observed. It was proved that, the interaction of CS@ZnS:Mn D-dots with BSA under UV illumination is mainly a result of a photo-induced free radical procedure. CS@ZnS:Mn D-dots may be used as photosensitizers in photodynamic therapy.
Keywords: Doped semiconductor nanocrystals; Chitosan; Bovine serum albumin; Interaction; UV illumination;

Laser-assisted atom probe tomography (LA-APT) was applied to SiN thin films with enriched 15N isotope in order to investigate the possibility of obtaining the nitrogen distribution in silicon-based structures by LA-APT analyses. SiN films with the ratio 14N:15N of ∼0:1 (Si15N) and ∼1:1 (Si14N15N) were formed on Si substrates, and measured by LA-APT under the usage of 355 nm-wavelength pulsed laser. The mass spectra obtained showed that the nitrogen counts were dominated by N2 +. The peak-tops of 30Si++ and 15N+, as well as those of 30Si+ and 15N2 +, were resolved in the mass spectrum of Si15N. It demonstrated that nitrogen distribution could be examined quantitatively as well as qualitatively.
Keywords: Atom probe; Laser-assisted atom probe; SiN; Nitride; Isotope;

In situ synthesized TiC–DLC nanocomposite coatings on titanium surface in acetylene ambient by Y.R. Xu; H.D. Liu; Y.M. Chen; M.I. Yousaf; C. Luo; Q. Wan; L.W. Hu; D.J. Fu; F. Ren; Z.G. Li; Q.S. Mei; B. Yang (93-100).
TiC–DLC coatings were in situ synthesized on Ti target surface in acetylene ambient by cathodic arc evaporation. In this process, TiC–DLC composite phases were formed by chemical reaction between Ti target surface and ionized C ions. Different acetylene (C2H2) flow rate and synthetic time were designed as two independent variables to synthesize two series of coatings to study the effects of different synthetic parameters on structure of the coatings. Surface morphology, composition and structure of the coatings were investigated by SEM, EDS, XRD and Raman spectroscopy, respectively. The result showed that the structure and composition of the coatings on the titanium metal target surface could be controlled by changing the C2H2 flow rate. The uniform TiC-DLC composite phases were observed in the coatings, while both C2H2 flow rate and synthetic time could significantly affect the thickness and bonding state of the coatings.
Keywords: TiC–DLC coating; Cathodic arc; In situ synthesis; C2H2 flow rate;

Surface treatment of polyimide substrates for the transfer and multitransfer of graphene films by Nuria Campos; Ana M. Perez-Mas; Patricia Alvarez; Rosa Menéndez; David Gómez (101-107).
This work explores the use of polyimide substrates for the development of flexible graphene-based devices. Single layer graphene was synthesized by chemical vapour deposition and transferred to untreated and treated polyimide substrates. Of the four different surface treatments, the tetrafluoromethane/oxygen plasma and, especially, hydrochloric acid bath treatments showed the best performance, as they reduced the resistivity of the graphene samples by as much as 46%. At the same time, resistivity was also reduced by as much as 96% due to the increase in the graphene coverage area as a result of repeating the transfer process up to four times. The combination of HCl treatment and transfer iteration led to the samples acquiring a sheet resistance of 800 Ω/sq. To the best of our knowledge, this is the lowest value ever reported in the literature for graphene samples on conventional flexible polymeric substrates and, in particular, in polyimide, the most widely used material for flexible applications. This result represents a major contribution to the development of graphene-based flexible devices.
Keywords: Graphene synthesis; Chemical vapour deposition; Graphene transfer; Polyimide; Plasma treatment; Wet chemical treatment;

A molybdate conversion coating (MCC) thin film was deposited on electroless Ni–P (ENP) coating by treating in an alkaline chemical conversion bath. A chromate conversion coating (CCC) was also prepared for comparison. Surface morphology of the conversion coatings exhibited no obvious difference with the as-plated ENP coating. Acid exposure test indicated that the oxidation resistance of the MCC was improved about 45 times higher than that of untreated ENP coating, respectively. The corrosion current density (i corr) values for both passivated surfaces were dramatically reduced by conversion treatment. However, MCC specimen showed the lowest i corr value of 0.19 μA cm−2 compared to 6.55 μA cm−2 for ENP and 0.38 μA cm−2 for CCC. EIS studies revealed that the MCC thin film possessed the highest charge transfer resistance (R ct) value, about 5 times higher than the CCC. XPS analysis indicated that the MCC thin film was made up of Ni, P, O, and Mo; the values of binding energy (BE) implied that both Ni and P participated in the formation of conversion coating thin film and the Mo was in the form of MO3.
Keywords: Chromium-free; Electroless Ni–P coating; Molybdate conversion coating; Corrosion resistance; XPS;

Potential of ITO nanoparticles formed by hydrogen treatment in PECVD for improved performance of back grid contact crystalline silicon solar cell by Sourav Mandal; Suchismita Mitra; Sukanta Dhar; Hemanta Ghosh; Chandan Banerjee; Swapan K. Datta; Hiranmoy Saha (116-122).
This paper discusses the prospect of using indium tin oxide (ITO) nanoparticles as back scatterers in crystalline silicon solar cells instead of commonly used metal nanoparticles as ITO nanoparticles have comparatively low dissipative losses and tunable optical properties. ITO nanoparticles of ∼5–10 nm size is developed on the rear side of the solar cell by deposition of ∼5–10 nm thick ITO layer by DC magnetron sputtering followed by hydrogen treatment in PECVD. The silicon solar cell is fabricated in the laboratory using conventional method with grid metal contact at the back surface. Various characterizations like FESEM, TEM, AFM, XRD, EQE and IV characteristics are performed to analyze the morphology, chemical composition, optical characteristics and electrical performance of the device. ITO nanoparticles at the back surface of the solar cell significantly enhances the short circuit current, open circuit voltage and efficiency of the solar cell. These enhancements may be attributed to the increased absorption and carrier collection at longer wavelengths of solar spectrum due to enhanced light trapping by the ITO nanoparticles and surface passivation by the hydrogen treatment of the back surface.
Keywords: ITO nanoparticle; Silicon solar cell; Light trapping; Surface passivation; Magnetron sputtering; PECVD;

Modification of mechanical properties of Si crystal irradiated by Kr-beam by Xiaowei Guo; Sadao Momota; Noriko Nitta; Takaharu Yamaguchi; Noriyuki Sato; Hideto Tokaji (123-128).
The application of ion-beam irradiation in fabrication of structures with micro-/nanometer scale has achieved striking improvement. However, an inevitable damage results in the change of mechanical properties in irradiated materials. To investigate the relation between mechanical properties and ion-irradiation damages, nanoindentation was performed on crystalline silicon irradiated by Kr-beam with an energy of 240 keV. Modified Young's modulus and nanohardness, provided from the indentation, indicated fluence dependence. Stopping and range of ions in matter (SRIM) calculation, transmission electron microscopy (TEM) observation, and Rutherford backscattering-channeling (RBS-C) measurement were utilized to understand the irradiation effect on mechanical properties. In addition, the longitudinal size of the phase transition region induced by indentation was firstly evaluated based on the depth profile of modified nanohardness.
Keywords: Young's modulus; Hardness; Crystalline silicon; Ion-beam irradiation;

The montmorillonite@carbon (MMT@C) composite was synthesized by the one-step hydrothermal carbonization process. U(VI) sorption on MMT@C from aqueous solution was investigated by using batch experiments. The maximum capacity of MMT@C toward U(VI) was 20.76 mg g−1 at pH 3.95, which was much higher than that of the raw MMT. The decoration of the functional carbonaceous species on the MMT@C improved its sorption capacity. U(VI) sorption on the MMT@C was an endothermic process. The inner-sphere surface complexation might be the primary sorption mechanism. MMT@C was a promising material for pre-concentration and immobilization of U(VI) from large volumes of aqueous solution.
Keywords: Montmorillonite; Carbon; Uranium; Sorption;

Effect of O2 on reduction of NO2 with CH4 over gallium-modified ZnAl2O4 spinel-oxide catalyst by first principle analysis by Chao Xiang; Honglin Tan; Jiansheng Lu; Lan Yu; Peng Song; Chunhua Zeng; Yong Liang; Shigang Tao; Zhibin Chen (138-146).
The effect of O2 toward selective catalytic reduction (SCR) of NO2 with CH4 on the surface of gallium-modified ZnAl2O4 catalyst has been investigated by first-principles calculations based on density functional theory (DFT). The studies show that NO2 interacts with Ga via its N side with a high adsorption energy of −56.33 kcal mol−1 stronger than other molecules, such as H2O, O2, CH4, CO2 and N2. Among them, the H2O prefers to adsorb on Zn rather than Ga as the active component. Additionally, O2 and NO2 co-adsorption is strongly repulsive. O2 has a negligible effect on stiffness of H―C (O―N) bond. Repulsion between the reactant and O2 is responsible for the formation of much weaker metal–adsorbate bonds (Ga―N and Al―C bonds). Instead, negative repulsion between the product and O2 results in formation of much stronger surface–adsorbate bonds (Zn―O, Al―C and Ga―N bonds). In addition, enthalpies of reaction in the presence and absence of O2 are −195.53 and −165.30 kcal mol−1, respectively. Both reactant and product are raised to higher energy level after O2 adsorption on the catalyst surface. O2 decreases activation energy of CH4 ―NO2 SCR reaction and causes a lowering of SCR reaction temperature.
Keywords: Co-adsorption; Repulsion; Reaction enthalpy; Activation energy; SCR reaction temperature;

In this report, water dispersions of pristine, amine-functionalized, and carboxyl-functionalized single-wall carbon nanotubes were introduced into model DNA amplification reactions in order to exploit the effects of surface charge, dispersion quality, and concentration of the carbon nanomaterials in the final amplification yield. The magnetic beads that were covalently modified with the functionalized carbon nanotubes were also evaluated under equal conditions to observe the difference between bulk and surface-attached nanotubes.The centrifugation and filtration steps applied to the bulk dispersions were found to be useful to eliminate aggregates, which ultimately enhanced the final amplification yields of the samples containing pristine and amine-functionalized carbon nanotubes. However, the carboxylated carbon nanotubes displayed an inhibitory action in all samples, regardless of the centrifugation and filtration, indicating a disfavored surface charge. The magnetic beads modified with the amine-functionalized carbon nanotubes also improved the amplification yield; besides, they greatly simplified the elimination of the nanotubes from reactions.Mechanism studies proved the preferential binding of the DNA templates onto the amine-functionalized nanotubes during amplification. Meanwhile, none of the DNA templates showed interaction with the carboxyl-functionalized carbon nanotubes, probably due to the electrostatic repulsion between the negative charges.
Keywords: Functionalized single-wall carbon nanotube; Dynamic light scattering; Dispersion state; Polymerase chain reaction; Random DNA library;

Structural modification for carbon nanotube film and the composite film by processing optimization by Yanjie Wang; Min Li; Yizhuo Gu; Shaokai Wang; Qingwen Li; Zuoguang Zhang (156-162).
As a kind of 2D macroscopic assembly of carbon nanotube (CNT), CNT film fabricated from CNT array performs outstanding properties and potential applications in many areas. For CNT film fabricated from spinnable array, the nanotube's alignment and packing density are two important factors for improving the properties. In this work, inspired by the unique transferring process, we intended to adjust the CNT stacking status in the film via optimizing the winding process and assisting appropriate post-treatment. Array-based CNT films with different winding parameters were fabricated to study the effect of winding speed and winding thickness on the film's tensile properties. It is revealed that related with the drawing force, the winding speed plays an important role in tuning CNTs arrangement in nanotube sheet. Within a certain range, increasing speed is helpful to straighten and uniformly disperse nanotubes, and further improve the tensile properties of the film. While for winding thickness, appropriate reducing thickness is favorable for sheets compaction and decreasing defects, which further enhance the properties. Additionally, combining the low elongation feature of array-based CNT film, little-ratio post-stretching is applied on the films, which is also proved to be efficient for densifying and aligning, stimulating the film stronger and more conductive simultaneously.
Keywords: Array-based carbon nanotube film; Winding process; Stretching; Alignment; Tensile property;

The site-selective deposition behavior of perylene onto a self-assembled monolayers (SAMs) patterned substrate was studied using the equilibrium and steered molecular dynamics simulations. Four kinds of different densely packed SAMs were constructed on silicon oxide substrates as the patterned templates. Equilibrium MD simulations showed that the packing density of alkyl chains on the substrate could influence the deposition behavior of the organic molecules. The potential of mean force (PMF) of the deposition process of perylene onto different density packed SAMs, which was calculated by the umbrella sampling with the weighted histogram analysis method (WHAM), determined the favorite location of perylene on the SAM. The equilibrium and non-equilibrium MD methods gave the same conclusion about the deposition positions of organic molecules on the patterned substrate. In summary, this comprehensive study is expected to provide useful information for the synthesis of new functional materials.
Keywords: Self-assembled monolayers; Site-selective deposition; Molecular dynamics; Umbrella sampling;

Fabrication of superhydrophobic surfaces with nano-in-micro structures using UV-nanoimprint lithography and thermal shrinkage films by Young Hoon Sung; Yang Doo Kim; Hak-Jong Choi; Ryung Shin; Shinill Kang; Heon Lee (169-173).
After forming the nanoscale pillar patterns on the thermal shrinkage films (TSFs) with nano imprint lithography (NIL), the TSFs were shrunk. Thus, the nano- and microscale complex structures which have superhydrophobic and oleophobic surfaces with nano- and micro-patterns were created. The nano- and microscale complex-patterned (NMCP) TSFs were then coated with a self-assembled monolayer to reduce the surface energy of the structures. After the surface treatment, the contact angle of water on NMCP was measured to be 150.3°, with the films exhibiting self-cleaning behavior. We used the NMCP TSF as a master stamp. By using UV-nanoimprint lithography, the NMCP pattern of polyurethane acrylate was successfully duplicated on a glass substrate. The duplicated NMCP pattern from master stamp had a contact angle with water of 149.8° with superhydrophobicity.
Keywords: Nano imprint lithography; Super hydrophobic; Thermal shrinkage film; Hierarchical structure;

Fabrication of highly electro catalytic active layer of multi walled carbon nanotube/enzyme for Pt-free dye sensitized solar cells by Alvira Ayoub Arbab; Kyung Chul Sun; Iftikhar Ali Sahito; Muhammad Bilal Qadir; Sung Hoon Jeong (174-183).
Highly dispersed conductive suspensions of multi walled carbon nanotubes (MWCNT) can have intrinsic electrical and electrochemical characteristics, which make them useful candidate for platinum (Pt)-free, dye sensitized solar cells (DSSCs). High energy conversion efficiency of 7.52% is demonstrated in DSSCs, based on enzyme dispersed MWCNT (E-MWCNT) layer deposited on fluorine doped tin oxide (FTO) glass. The E-MWCNT layer shows a pivotal role as platform to reduce large amount of iodide species via electro catalytically active layer, fabricated by facile tape casting under air drying technique. The E-MWCNT layer with large surface area, high mechanical adhesion, and good interconnectivity is derived from an appropriate enzyme dispersion, which provides not only enhanced interaction sites for the electrolyte/counter electrode interface but also improved electron transport mechanism. The surface morphology and structural characterization were investigated using field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electronic microscopy techniques. Electro catalytic activity (ECA) and electrochemical properties of E-MWCNT counter electrode (CE) were investigated using cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements. The high power conversion efficiency (PCE) of E-MWCNT CE is associated with the low charge transfer resistance (R CT  = 1.39 Ω cm2) and excellent electro catalytic activity on the redox of the iodide/tri-iodide pair, as discovered by the cyclic voltammetry and electrochemical impedance spectroscopy investigations. This facile E-MWCNT configuration provides a concrete fundamental background towards the development of the third generation photovoltaic devices.
Keywords: Multi walled carbon nanotube; Enzyme; Electro catalytic activity; Charge transfer resistance; Dye sensitized solar cell;

Au nanoparticles on tryptophan-functionalized graphene for sensitive detection of dopamine by Qianwen Lian; Ai Luo; Zhenzhen An; Zhuang Li; Yongyang Guo; Dongxia Zhang; Zhonghua Xue; Xibin Zhou; Xiaoquan Lu (184-189).
A novel and uniform gold nanoparticles/tryptophan-functionalized graphene nanocomposite (AuNPs/Trp-GR) has been successfully fabricated by directly electrochemical depositing gold onto the surface of tryptophan-functionalized graphene (Trp-GR). The nanostructure of AuNPs/Trp-GR was characterized by using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). It was demonstrated that Au nanoparticles were well dispersed on the surface of Trp-GR which might attribute to the more binding sites provided by Trp-GR for the formation of Au nanoparticles. The electrocatalytic activity of the AuNPs/Trp-GR towards the dopamine (DA) was systematically investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimum conditions, a wide and valuable linear range (0.5–411 μM), a low detection limit (0.056 μM, S/N = 3), good repeatability and stability were obtained for the determination of DA. Furthermore, the modified electrode was successfully applied to real samples analysis.
Keywords: Gold nanoparticle; Tryptophan; Graphene; Electrochemical deposition; Dopamine;

Fabrication of highly active and cost effective SERS plasmonic substrates by electrophoretic deposition of gold nanoparticles on a DVD template by Cosmin Leordean; Bogdan Marta; Ana-Maria Gabudean; Monica Focsan; Ioan Botiz; Simion Astilean (190-195).
In this work we present a simple, rapid and cost effective method to fabricate highly active SERS substrates. This method consists in an electrophoretic deposition of gold nanoparticles on a metallic nanostructured template of a commercial digital versatile disk (DVD). The negatively charged gold nanoparticles self-assemble on the positively charged DVD metallic film connected to a positive terminal of a battery, due to the influence of the electric field. When gold nanoparticles self-assembled on DVD metallic film, a 10-fold additional enhancement of Raman signal was observed when compared with the case of GNPs self-assembled on a polycarbonate DVD substrate only. Finite-difference time-domain simulations demonstrated that the additional electromagnetic field arising in the hot-spots created between gold nanoparticles and DVD metallic film induces an additional enhancement of the Raman signal. SERS efficiency of the fabricated plasmonic substrate was successfully demonstrated through detection of para-aminothiophenol molecule with three different excitation laser lines (532, 633 and 785 nm). The enhancement factor was calculated to be 106 and indicates that plasmonic substrates fabricated through this method could be a promising platform for future SERS based sensors.
Keywords: Plasmonic nanostructures; Electrophoretic deposition; Digital versatile disk; SERS;

Radius ratio rule for surface hydrophilization of polydimethyl siloxane and silica nanoparticle composite by Vijaykumar Toutam; Puneet Jain; Rina Sharma; Sivaiah Bathula; Ajay Dhar (196-199).
Polydimethyl siloxane (PDMS) and Silica (SiO2) nanoparticle composite blocks of three different batches (CB1–CB3) made by varying the size of SiO2 nanoparticles (NP), are studied for the degree of hydrophilization and retainability after oxidation by contact angle measurements (CA) and force distance spectroscopy (FDS) using Atomic Force Microscope (AFM). While CA measurements have shown high hydrophilization and retainability for CB3, F-D spectroscopy has reiterated the observation and has shown long range interactive forces and high Debye length of the electrostatic double layer formed. These results are in agreement with the radius ratio rule of binary sphere system for high density packing in the composite and thereby for strong hydrophilization and retainability due to reinforcement and restricted diffusion of uncured polymer.
Keywords: Microfluidic; PDMS; Contact angle; F-D spectroscopy; Electrostatic double layer;

Highly hydrophilic poly(ethylene terephthalate) films prepared by combined hot embossing and plasma treatment techniques by D. Jucius; V. Kopustinskas; V. Grigaliūnas; A. Guobienė; A. Lazauskas; M. Andrulevičius (200-210).
Combined hot embossing and low pressure RF plasma treatment techniques were used with the aim to enhance surface wettability of biaxially oriented semicrystalline poly(ethylene terephthalate) (PET) films. Produced by industrial stretch-blow molding PET film of the 300 μm thickness was chosen for the experiments. Hot embossing of the prepatterned Ni stamp led to additional crystallization and the increment in effective surface area of the polymer. One set of the embossed samples was treated by CF4 plasma, while the other was successively treated by O2 and CF4 plasma. Changes in the dimensions of the embossed bumps were observable after the plasma treatment due to the release of frozen internal stresses. Nanoroughening of the surface associated with the plasma treatment was more significant for the O2 and CF4 plasma treated PET. Surfaces of both sample sets were hydrophobic immediately after the plasma treatment due to the large amount of incorporated fluorine. However, wetting tended to increase rapidly during the first days of ageing. After 10 days of storing, average water contact angle was about 20° for the hot embossed and CF4 plasma treated PET films, and it was about 11° for the hot embossed and successively O2 and CF4 plasma treated films. Further ageing up to 60 days have not revealed noticeable changes in the surface wetting. So, combined hot embossing and plasma treatment techniques were found to be beneficial for the enhancement of the surface wetting compared to plasma treatment alone.
Keywords: Polyethylene terephthalate; Plasma treatment; Hot embossing; Contact angle; Hydrophilicity; Ageing;

This paper presents a novel view on ice repellency of superhydrophobic surfaces in terms of contact angle hysteresis, surface roughness and icing condition. Ice repellency performance of two superhydrophobic silicone rubber nanocomposite surfaces prepared via spin coating and spray coating methods were investigated. High contact angle (>150°), low contact angle hysteresis (<6°) and roll-off property were found for both spin and spray coated samples. The results showed a significant reduction of ice adhesion strength on the spin-coated sample while ice adhesion strength on the spray-coated sample was found to be unexpectedly similar to that of the uncoated sample. Indeed, this research study showed that the icephobic properties of a surface are not directly correlated to its superhydrphobicity and that further investigations, like taking icing condition effect into account, are required. It was found that icephobic behaviour of the spray coated sample improved at lower levels of liquid water content (LWC) and under icing conditions characterized by smaller water droplet size.
Keywords: Ice adhesion; Superhydrophobic; Roughness; Icing condition; Liquid water content; Water droplet size;

Si-based cadmium sulfide (CdS) is a prospective semiconductor system in constructing optoelectronic nanodevices, and this makes the study on the factors which may affect its optical and electrical properties be of special importance. Here we report that CdS thin film was grown on Si nanoporous pillar array (Si-NPA) by a chemical bath deposition method, and the luminescent properties of CdS/Si-NPA as well as its mechanism were studied by measuring and analyzing its temperature-dependent photoluminescence (PL) spectrum. The low-temperature measurement disclosed that the PL spectrum of CdS/Si-NPA could be decomposed into four emission bands, a blue band, a green band, a red band and an infrared band. The blue band was due to the luminescence from Si-NPA substrate, and the others originate from the CdS thin film. With temperature increasing, the peak energy, PL intensity and peak profile shape for the PL bands from CdS evolves differently. Through theoretical and fitting analyses, the origins of the green, red and infrared band are attributed to the near band-edge emission, the radiative recombination from surface defects to Cd vacancies and those to S interstitials, respectively. The cause of PL degradation is due to the thermal quenching process, a phonon-induced electron escape but with different activation energies. These results might provide useful information for optimizing the preparing parameters to promote the performance of Si-based CdS optoelectronic devices.
Keywords: Silicon nanoporous pillar array (Si-NPA); Cadmium sulfide (CdS); CdS/Si-NPA; Temperature-dependent photoluminescence (PL);

Elucidating the electrostatic interaction of sulfonic acid functionalized SBA-15 for ciprofloxain adsorption by Jinsuo Gao; Yong Lu; Xueying Zhang; Jingjing Chen; Shutao Xu; Xiaona Li; Xinyong Li; Feng Tan (224-229).
Though adsorption is a promising method to treat anitibotics pollution, the complexity of many kinds of antibiotics molecules and the multiple roles of organic functional groups in organo-functionalized mesoporous silicas adsorbents cause diverse interactions between the antibiotics and the adsorbents. Here, we prepared SBA-15, SH-SBA-15 and SO3H-SBA-15 with comparable textural and structural property for the adsorption of ciprofloxain to elucidate the dual roles of organic functional groups. It is found that the beneficial electrostatic interaction of SO3H-SBA-15 precedes its disadvantageous hydrophilicity for adsorption, which is different from amine functionalized mesoporous materials as reported elsewhere. The potential antibiotics adsorbents, SO3H-SBA-15, could be reused 3 times without obvious decrease of adsorption property.
Keywords: Mesoporous; Organo-functionalization; Adsorption; Antibiotics pollution;

Oxygen-doped Sb2Te3 for high-performance phase-change memory by You Yin; Shota Morioka; Shun Kozaki; Ryoya Satoh; Sumio Hosaka (230-234).
In this study, we intensively investigated oxygen doped Sb2Te3 (ST–O) for high-performance phase-change memory (PCM) based on X-ray diffraction analysis and electrical measurements. The crystal became more ordered with increasing annealing temperature and the lattice deformed with the interstitial sites occupied by doped O atoms. It also exhibited that mean crystal size decreased from 8 nm to 3 nm and thus crystal growth was significantly suppressed by fine oxides due to O-doping. The resistivity of crystalline O–ST could be around 3–4 orders of magnitude higher than that of crystalline ST, which enables great reduction in reset current. It was clear that the high resistivity was able to be tuned simply by doping O into the conventional ST phase-change material for improving the performance of PCM.
Keywords: Phase-change material; Nonvolatile memory; Phase-change memory; High performance;

We performed atmospheric pressure plasma treatments of pure cashmere and wool/cashmere textiles with a dielectric barrier discharge (DBD) in humid air (air/water vapor mixtures). Treatment parameters have been optimized in order to enhance the wettability of the fabrics without changing their bulk properties as well as their touch. A deep characterization has been performed to study the wettability, the surface morphologies, the chemical composition and the mechanical properties of the plasma treated textiles. The chemical properties of the plasma treated samples were investigated with attenuated total reflectance Fourier transform infrared (FTIR/ATR) spectroscopy and X-ray photoelectron microscopy (XPS). The analyses reveal a surface oxidation of the treated fabrics, which enhances their surface wettability. Morphological characterization of the treated fibers with scanning electron microscopy (SEM) reveals minor etching effects, an essential feature for the maintenance of the textile softness.
Keywords: Atmospheric pressure plasma treatment; FTIR/ATR; Wettability; XPS; SEM;

Fabrication of a novel visible-light-driven photocatalyst Ag-AgI-TiO2 nanoparticles supported on carbon nanofibers by Dandan Yu; Jie Bai; Haiou Liang; Junzhong Wang; Chunping Li (241-250).
Novel visible-light-driven photocatalysts Ag-AgI-TiO2 nanoparticles embedded onto carbon nanofibers were successfully prepared. Electrospinning technology followed by high-temperature calcination was adopted for the fabrication of carbon nanofibers (CNFs) acting as a supporter. Ag-TiO2/CNFs nanocomposites were prepared by combining in situ reduction with physical adsorption process. Ag-AgI-TiO2/CNFs were synthesized by oxidizing some silver nanoparticles (Ag NPs) contained in Ag-TiO2/CNFs to silver iodine (AgI) via chemical oxidation method using iodine (I2) as oxidation agents. The as-prepared nanocomposites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS), and Fourier transform infrared spectroscopy (FTIR). The as-fabricated Ag-AgI-TiO2/CNFs showed high efficient adsorption and photocatalytic activity for decomposition of methyl orange (MO), acid red 18 (AR18), methylene blue (MB), and fluorescence sodium under visible light irradiation, which were attributed to the synergistic effects between the high adsorption capacity, good conductivity of carbon nanofibers, and the extraordinary plasma effect of Ag-AgI nanoparticles. In addition, the as-prepared composites could be easily separated from the solution phase due to the large length–diameter ratio of CNFs. The mechanism for the enhanced photocatalytic activity concerned with Ag-AgI-TiO2/CNFs was proposed.
Keywords: Carbon nanofibers; Electrospinning; Photocatalysis; Silver iodine; Titanium dioxide;

Monolithic porous rectorite/starch composites: fabrication, modification and adsorption by Fei Wang; Peter R. Chang; Pengwu Zheng; Xiaofei Ma (251-258).
The monolithic rectorite/starch composites (PRSs) were fabricated by freezing the composite gels and exchanging ice with ethanol to obtain the porous structures. The rectorite layers were randomly oriented and covered with starch in the monolithic PRSs. Two modifications were treated without destroying the porous structures. Starch components were removed to obtain the calcinated PRSs (CPRSs); and starch components reacted with carbon disulfide to obtain the porous rectorite/starch xanthate composites (PRSXs). PRSs, CPRSs and PRSXs exhibited low density and high liquid adsorption due to the porous structures. CPRSs possessed the higher MB adsorption capacity than PRSs, because the resistance of starch on MB adsorption was eliminated. The chelation could form between xanthate groups and Pb (II), and improve the adsorption of Pb (II) of PRSXs. The maximum adsorption capacities could reach 277.0 and 180.8 mg g−1 for MB by CPRS and Pb (II) by PRSX, respectively. Moreover, CPRS could be effectively recycled by burning away the adsorbed MB dye; while PRSX could be easily regenerated with ethylenediaminetetraacetic acid disodium salt (EDTA) solution. The modification of PRSs had the potential applications on the treatment of cationic contaminations in water.
Keywords: Starch; Rectorite; Porous materials; Modification; Adsorption;

Synthesis and properties of crystalline thin film of antimony trioxide on the Si(1 0 0) substrate by M. Yasir; M. Kuzmin; M.P.J. Punkkinen; J. Mäkelä; M. Tuominen; J. Dahl; P. Laukkanen; K. Kokko (259-263).
Atomic-scale understanding and processing of the surface and interface properties of antimony trioxide (Sb2O3) are essential to the development of nanoscale Sb2O3 materials for various applications, such as photocatalysts, transparent conducting oxides, optical coatings, dielectric films, and fire retardants. Lack of atomically well-defined, crystalline Sb2O3 templates has however hindered atomic resolution characterization of the Sb2O3 properties. We report the preparation of crystalline Sb2O3 thin films on the Si(1 0 0) substrate with a simple process by oxidizing Sb-covered Si(1 0 0) in proper conditions. Physical properties of the synthesized films have been elucidated by low-energy electron diffraction, scanning tunneling microscopy and spectroscopy, and ab initio calculations. The spectroscopic results show that the band gap of Sb2O3 is 3.6 eV around the gamma point (i.e. Γ). Calculations reveal energetically favored Sb2O3(1 0 0) surface structures. The findings open a new path for the atomic-scale research of Sb2O3.
Keywords: Sb2O3; Silicon; Crystalline oxide; Band gap; Microscopy; Spectroscopy;

Floating photocatalysts of boron-nitrogen codoped TiO2 grafted on expanded perlite (B-N-TiO2/EP) were prepared by a facile sol–gel method. The catalysts were characterized by N2 adsorption–desorption (BET), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (UV–vis–DRS). The results revealed that the physicochemical properties of the photocatalysts, such as BET surface area, porosity and pore size could be controlled by adjusting the calcination temperature and EP dosage. XRD patterns were mainly influenced by calcination temperature and the transformation of anatase to rutile occurred at 650 °C. Uniform TiO2 loading, higher surface area and absorption in visible light region were obtained for B-N-TiO2/EP calcined at 550 °C with 3.0 g EP addition. Moreover, photocatalytic activity for RhB destruction under visible light irradiation was slightly influenced by TiO2 loading in the range of 1–3 g EP dosage. BNTEP550 showed the highest photocatalytic activity indicating to be a promising photocatalyst employed to remediate contaminated waters using solar irradiation.
Keywords: B-N codoping; TiO2; Floating; Visible light; Photocatalyst; Rhodamine B;

A simple solvothermal process to synthesize CaTiO3 microspheres and its photocatalytic properties by Weixia Dong; Bin Song; Weijie Meng; Gaoling Zhao; Gaorong Han (272-278).
Novel CaTiO3 microspheres composed of nanosheets have been successfully prepared via a very simple solvothermal process in ethanol aqueous solution without any template or surfactant. The microstructure and morphology are characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy. The effects of the reaction time, reaction temperature, and molar ratio of ethanol/water on the formation of the spherical structure have been investigated. CaTiO3 microspheres assembled by nanosheet units have been obtained by controlling the molar ratio of water/ethanol. The growth mechanism has been proposed based on the results of time-dependent experiments. It is proposed that amorphous particles transformed to nanosheets, and nanosheets self assembly into solid microspheres, then nanosheets building units further oriented growth along [1 1 0] direction result in the formation of nanosheets building units, and finally form the microsphere composed of nanosheets. CaTiO3 microspheres show higher photocatalytic activity than randomly aggregated nanosheets. In addition, CaTiO3 microspheres are stable during the photocatalytic reaction and more convenient to store and handle as a micrometre-scale structure.
Keywords: Simple solvothermal process; CaTiO3; Microspheres; Photocatalytic properties;

Facile synthesis of CdS@TiO2 core–shell nanorods with controllable shell thickness and enhanced photocatalytic activity under visible light irradiation by Wenhao Dong; Feng Pan; Leilei Xu; Minrui Zheng; Chorng Haur Sow; Kai Wu; Guo Qin Xu; Wei Chen (279-286).
Amorphous TiO2 layers with a controllable thickness from 3.5 to 40 nm were coated on the one-dimensional CdS nanorods surface under mild conditions. Compared to the bare CdS nanorods, the as-prepared CdS@TiO2 nanorods exhibit enhanced photocatalytic activities for phenol photodecomposition under visible light irradiation. The improved photoactivity is ascribed to the efficient separation of photogenerated electron and hole charge carriers between CdS cores and TiO2 shells. This study promises a simple approach to fabricating CdS@TiO2 core–shell structure nanocomposites, and can be applied for other semiconductor cores with TiO2 shells.
Keywords: CdS@TiO2; Core–shell nanocomposite; Controllable shell thickness; Visible-light photocatalyst;

Photoluminescence properties of Bi/Al-codoped silica optical fiber based on atomic layer deposition method by Jianxiang Wen; Jie Wang; Yanhua Dong; Na Chen; Yanhua Luo; Gang-ding Peng; Fufei Pang; Zhenyi Chen; Tingyun Wang (287-291).
The Bi/Al-codoped silica optical fibers are fabricated by atomic layer deposition (ALD) doping technique combing with conventional modified chemical vapor deposition (MCVD) process. Bi2O3 and Al2O3 are induced into silica optical fiber core layer by ALD technique, with Bis (2,2,6,6-tetra-methyl-3,5-heptanedionato) Bismuth(III) (Bi(thd)3) and H2O as Bi and O precursors, and with Al(CH3)3 (TMA) as Al precursor, respectively. The structure features and optical properties of Bi/Al-codoped silica optical fibers are investigated. Bi2O3 stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence state of Bi element is +3. Concentration distribution of Si, Ge and O elements is approximately 24–33, 9 and 66 mol%, respectively, in fiber preform core and cladding layer region. Bi and Al ions have been also slightly doped approximately 150–180 and 350–750 ppm in fiber preform core, respectively. Refractive index difference of the Bi/Al-codoped fiber is approximately 0.58% using optical fiber refractive index profiler analyzer. There are obvious Bi-type ions absorption peaks at 520, 700 and 800 nm. The fluorescence peaks are at 1130 and 1145 nm with 489 and 705 nm excitations, respectively. Their fluorescence lifetimes are 701 and 721 μs, respectively. And then there are obvious fluorescence bands in 600–850 and 900–1650 nm with 532 nm pump exciting. There is a maximum fluorescence intensity peak at 1120 nm, and its full wave at half maximum (FWHM) is approximately 180 nm. These may mainly result from the interaction between Bi and Al ions. The Bi/Al-codoped silica optical fibers would be used in high power or broadly tunable laser sources, and optical fiber amplifier in the optical communication fields.
Keywords: Photoluminescence property; Bi/Al-codoped silica materials; Atomic layer deposition; Silica optical fiber;

Plasmonic Au/CdMoO4 photocatalyst: Influence of surface plasmon resonance for selective photocatalytic oxidation of benzylic alcohol by Jinhong Bi; Zhiyong Zhou; Mengying Chen; Shijing Liang; Yunhui He; Zizhong Zhang; Ling Wu (292-298).
Novel visible-light-driven plasmonic Au/CdMoO4 photocatalysts were synthesized by hydrothermal process following chemical reduction process. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, UV–vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The results show the catalysts exhibited strong visible light absorption due to the surface plasmon resonance effect of Au nanoparticles. Compared to CdMoO4, Au/CdMoO4 composites displayed superior photocatalytic activities for the selective oxidation of benzylic alcohol to benzaldehyde under visible light. The highest conversion was obtain by the 1.6% Au loaded CdMoO4. The mechanism for the selective oxidation of benzylic alcohol in the Au/CdMoO4 system is proposed.
Keywords: Au/CdMoO4 composites; Visible light; Surface plasmon resonance; Selective oxidation; Charge transfer mechanisms;

Structural properties of alumina supported Ce–Mn solid solutions and their markedly enhanced catalytic activity for CO oxidation by Perala Venkataswamy; Deshetti Jampaiah; Fangjian Lin; Ivo Alxneit; Benjaram M. Reddy (299-309).
This work presents the synthesis and characterization of alumina supported ceria–manganese solid solutions (Ce–Mn/Al), which were prepared by a deposition coprecipitation method followed by calcination at different temperatures from 773 to 1073 K. The physicochemical properties of the synthesized samples were deeply investigated by various characterization techniques, namely, XRD, ICP-OES, BET surface area, TEM-HRTEM, Raman, XPS, and H2-TPR. The catalytic activity was evaluated for CO oxidation. BET surface area measurements revealed that synthesized samples exhibit reasonably high specific surface area. XRD and Raman results confirmed that the present Ce–Mn/Al samples are single-phase solid solutions with good structural homogeneity and high thermal stability up to 1073 K. TEM analyses showed that the particle sizes of Ce–Mn/Al samples are in the range of ∼5–14 nm. XPS analysis revealed that Ce is in the form of Ce4+ and Ce3+, and Mn existed in the form of Mn4+, Mn3+, and Mn2+ on the surface of the samples. The solid solution particles in the nanosize form are well distributed over the support surface. As a result of solid solution formation and high dispersion over the support, the Ce–Mn/Al samples exhibited better redox behaviour. The CO oxidation results revealed that the Ce–Mn/Al samples show an excellent CO oxidation performance compared with alumina supported undoped CeO2 (Ce/Al) and MnO x (Mn/Al) samples. Among various samples, the Ce–Mn/Al calcined at 773 K showed outstanding CO activity with T 50  = ∼340 K. The enhanced catalytic activity was mainly attributed to high surface area, large amount of oxygen vacancies, and excellent redox behaviour. The metal–support interaction also seems to play a decisive role in their high catalytic activity by stabilizing the Ce–Mn–O dispersion.
Keywords: Solid solution; Oxygen vacancies formation; Synergistic interaction; High reducibility; CO oxidation;

The model thin film alumina catalyst support suitable for catalysis-oriented surface science studies by Anna V. Nartova; Andrey V. Bukhtiyarov; Ren I. Kvon; Valerii I. Bukhtiyarov (310-318).
The preparation of thin continuous alumina film at the surface of metal substrate in UHV (ultra high vacuum) conditions is described. The peculiarities of the obtained films studied by XPS (X-ray photoelectron spectroscopy) and STM (scanning tunneling microscopy) are discussed. The long-term durability of the oxide film was tested and proved both under ambient conditions and in acidic aqueous solutions. The stability of the planar alumina samples toward oxidation by oxygen was checked in the wide ranges of gas pressure and sample temperature. The suggested procedure ensures the controlled and reproducible preparation of thin alumina films – model support appropriate for wet chemistry catalyst preparation, suitable for STM and for other Surface Science techniques studies of alumina supported metal catalysts.
Keywords: Alumina film; STM; XPS; Model catalyst support;

Metallized glass fibers have the excellent electric conductivity and low price compared with carbon fibers. Metallized glass fibers were fabricated by coating copper on the surface using different processing technologies and the effects of processing technology on the properties of copper coated glass fibers were discussed. By hand laying up molding, metallized glass fiber reinforced plastic (MGFRP) with good dispersion and interfacial cohesion was prepared successfully. The piezoresistive properties of MGFRP were compared with those of carbon fiber reinforced plastic (CFPR). The results show that copper coated on glass fibers with volume resistivity of 10−5  Ω·cm have the good electrical conductivity and cohesion between two phases through optimizing the pretreatment technology of glass fibers and the formula of chemical plating solution. MGFRP has the distinct and similar piezoresistive characteristics with CFRP and exhibits the better piezoresistive sensitivity to fracture.
Keywords: Electroless plating; Copper; Glass fiber; Piezoresistive property;

Enhanced cytocompatibility of silver-containing biointerface by constructing nitrogen functionalities by Wei Zhang; Jun Liu; Huaiyu Wang; Ying Xu; Pingli Wang; Junhui Ji; Paul K. Chu (327-332).
Constructing nitrogen functionalities is promising method to enhance cytocompatibility of the biointerface by simultaneous Ag and N2 plasma modification.Silver (Ag) has recently been introduced into polymeric biomedical implants by plasma immersion ion implantation (PIII) to enhance the antibacterial capability. However, Ag ions and nanoparticles can increase the cytotoxicity and inhibit cellular proliferation and the relationship is time- and dose-dependent. In this study, Ag and N2 PIII is conducted in concert to produce nitrogen functional groups as well as Ag-containing biointerface. In addition to the creation of nitrogen functionalities, the surface roughness and hydrophilicity are improved in favor of protein adsorption. Compared to the biointerface created by Ag PIII only, the nitrogen functionalities generated by N2 co-PIII do not affect DNA synthesis and the total protein level but evidently enhance cellular adhesion, viability, and proliferation at the biointerface. The modified surface is observed to upregulate the osteogenesis-related marker expression of bone cells in contact. Our findings suggest that dual Ag and N2 PIII is a desirable technique to enhance both the cytocompatibility and antibacterial capability of medical polymers.
Keywords: Silver; N2 plasma immersion ion implantation; Polymeric implant; Antibacterial capability; Cytocompatibility;

Plasma induced vapor phase graft polymerization (PIVPGP) method was applied to modify aramid fiber surface. In this study, aramid fibers were pretreated under various plasma conditions such as different treatment times, output powers and working gases to see how these plasma processing parameters influenced the PIVPGP of acrylic acid (AA) on aramid fiber surface and its surface structure and properties. The analysis results of atomic force microscope (AFM) and X-ray photoelectron spectroscope (XPS) showed the increase of surface roughness and the introduction of O=C―OH, which confirmed that the PIVPGP of AA on aramid fiber surface was achieved. The contact angle and interfacial shear strength (IFSS) of the aramid fibers modified by PIVPGP of AA prominently decreased and increased, respectively, indicating the obvious improvements of surface wettability and adhesion between aramid fiber and matrix. The surface modification effects of aramid fiber by PIVPGP of AA firstly increased and then after 15 min slightly decreased with the increasing plasma treatment time, and but firstly increased and then after 300 W nearly remained unchanged with the increasing output power, respectively. Among different working gases, Ar plasma occupied first place, O2 plasma and N2 plasma came second and third in the aspect of PIVPGP of AA on aramid fiber surface, respectively. It could be concluded that the PIVPGP of AA on aramid fiber surface could effectively improve surface wettability and adhesion. Plasma conditions had signally influence on the efficiency of PIVPGP of AA on aramid fiber surface and its surface structure and properties with the primary sequence of plasma treatment time, output power and working gas. Therefore adequate plasma processing parameters should be carefully selected for the optimum surface modification of aramid fiber by PIVPGP of AA.
Keywords: Plasma induced vapor phase graft polymerization; Plasma processing parameters; Aramid fiber; Wettability; Adhesion;

Visible-light photocatalytic activities for selective oxidation of amines into imines are greatly affected by the crystal structure of TiO2 catalysts and mixed-phase TiO2(B)/anatase possess higher photoactivity because of the moderate adsorption ability and efficient charge separation.Wirelike catalysts of mixed-phase TiO2(B)/anatase TiO2, bare anatase TiO2 and TiO2(B) are synthesized via calcining precursor hydrogen titanate obtained from hydrothermal process at different temperatures between 450 and 700 °C. Under visible light irradiation, mixed-phase TiO2(B)/anatase TiO2 catalysts exhibit enhanced photocatalytic activity in comparison with pure TiO2(B) and anatase TiO2 toward selective oxidation of benzylamines into imines and the highest photocatalytic activity is achieved by TW-550 sample consisting of 65% TiO2(B) and 35% anatase. The difference in photocatalytic activities of TiO2 samples can be attributed to the different adsorption abilities resulted from their crystal structures and interfacial charge separation driven by surface-phase junctions between TiO2(B) and anatase TiO2. Moreover, the photoinduced charge transfer mechanism of surface complex is also proposed over mixed-phase TiO2(B)/anatase TiO2 catalysts. Advantages of this photocatalytic system include efficient utilization of solar light, general suitability to amines, reusability and facile separation of nanowires catalysts.
Keywords: Photocatalytic selective oxidation; Surface-phase junctions; TiO2; Amines; Charge transfer;

Laser ablation of molecular carbon nitride compounds by D. Fischer; K. Schwinghammer; C. Sondermann; V.W. Lau; J. Mannhart; B.V. Lotsch (353-360).
We present a method for the preparation of thin films on sapphire substrates of the carbon nitride precursors dicyandiamide (C2N4H4), melamine (C3N6H6), and melem (C6N10H6), using the femtosecond-pulsed laser deposition technique (femto-PLD) at different temperatures. The depositions were carried out under high vacuum with a femtosecond-pulsed laser. The focused laser beam is scanned on the surface of a rotating target consisting of the pelletized compounds. The resulting polycrystalline, opaque films were characterized by X-ray powder diffraction, infrared, Raman, and X-ray photoelectron spectroscopy, photoluminescence, SEM, and MALDI-TOF mass spectrometry measurements. The crystal structures and optical/spectroscopic results of the obtained rough films largely match those of the bulk materials.
Keywords: Pulsed laser deposition; Ultra-short laser; Carbon nitrides; Thin films; Properties;

We analyzed the process of using femtosecond and nanosecond pulsed lasers for removing the oxide layer from bulk copper and optimized the process parameters. A femtosecond laser (Ti:Sapphire) and two nanosecond lasers (Nd:YAG, excimer) were used to remove oxide layers composed of cupric oxide (CuO) and cuprous oxide (Cu2O) from copper. Femtosecond laser ablation reduced the thickness of native oxide layers to <20 nm with no significant thermal side effects. Nanosecond laser ablation removed a substantial portion of the oxides but thermal side effects such as surface melting and resolidification generated re-oxidation layers on the order of 100-nm thick.
Keywords: Laser ablation; Oxide removal; Copper oxide; Femtosecond laser; Nanosecond laser; Re-oxidation;

Surface properties of annealed semiconducting β-Ga2O3 (1 0 0) single crystals for epitaxy by A. Navarro-Quezada; Z. Galazka; S. Alamé; D. Skuridina; P. Vogt; N. Esser (368-373).
We present a detailed study on the surface properties of conductive β-Ga2O3 (1 0 0) single-crystal epiready substrates by means of photoelectron emission spectroscopy. The surface properties are studied prior and after annealing in ultra-high vacuum (UHV). We find that untreated substrates contain a significant amount of adsorbed carbon contaminations at the surface, which can be partly removed by annealing at 800 °C in UHV. Valence band photoemission evidences an upward band bending of about 0.5 eV that increases with annealing, revealing the presence of an electron depletion layer at the near-surface region responsible for the insulating behavior commonly observed for semiconductive β-Ga2O3 single crystals. Our findings become crucial for epitaxial growth, as it is known that carbon modifies the electrical and structural properties of subsequent epitaxial layers.
Keywords: Photoemission spectroscopy; Transparent oxides; Annealing;

In this paper, erythrocyte-like calcium molybdate (CaMoO4) hierarchical structures were successfully synthesized by a modified slow-release strategy. The structure of the as-prepared products was characterized by X-ray diffraction, Fourier transform infrared and Raman spectroscopy. The morphology was observed with scanning electron microscopy. A series of experiments of reaction conditions including reaction time, initial pH and molybdenum source were carefully carried out. The results showed that the slow release of MoO4 2− played a key role in the morphology of the products. Moreover, the photoluminescence spectrum of the erythrocyte-like CaMoO4 revealed a strong and broad emission peak at 536 nm. The erythrocyte-like CaMoO4 exhibited high removal rate for the methylene blue (MB), suggesting its potential application in water treatment.
Keywords: Inorganic compounds; Chemical synthesis; Electron microscopy; Surface properties;

Controlled synthesis of monodisperse WO3·H2O square nanoplates and their gas sensing properties by Bin Miao; Wen Zeng; Yuji Mu; Weijie Yu; Shahid Hussain; Sibo Xu; He Zhang; Tianming Li (380-386).
Monodisperse WO3·H2O square nanoplates were controlled synthesized under hydrothermal conditions with the adding of malic acid. The powders obtained under two different hydrothermal reaction times were characterized by X-ray powder diffraction (XRD) field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The thickness of the nanoplates would increase due to the prolongation of reaction time. In addition, the differences of exposure of crystal facets of this orthorhombic WO3·H2O square nanoplates were researched and its influence on the gas sensing properties were also discussed. Gas sensor based on the two obtained WO3·H2O square nanoplates powders was prepared and the gas responses to serious concentrations of C2H5OH gas were carried out. These kinds of nanoplates show excellent ethanol gas sensing and it can be influenced by the crystal facet percentage in nanoplates. This works show great significance to the control synthesis of semiconductor metal oxides and their applications in gas sensor research.
Keywords: Nanomaterials; Nanoparticles; Crystal structure; Gas sensing; WO3;

Metastable Ge nanocrystalline in SiGe matrix for photodiode by Yao-Tsung Ouyang; Chien-Hao Su; Jenq-Yang Chang; Shao-Liang Cheng; Po-Chen Lin; Albert T. Wu (387-392).
Amorphous Si1−x Ge x films were prepared by co-sputtering on an oxidized Si wafer, followed by rapid thermal annealing to form nanocrystal films. The formation of Ge nanocrystals was not at thermodynamic equilibrium formed in the amorphous Si1−x Ge x matrix. High-resolution transmission electron microscopy was used to characterize the increase in the size of the grains in the Ge nanocrystals as the Ge content increased. The Ge nanocrystals have a greater absorption in the near-infrared region and higher carrier mobility than SiGe crystals, and the variation in their grain sizes can be used to tune the bandgap. This characteristic was exploited herein to fabricate n-Si1−x Ge x /p-Si1−x Ge x p–n diodes on insulating substrates, which were then examined by analyzing their current–voltage characteristics. The rectifying property became stronger as the fraction of Ge in the Si1−x Ge x films increased. The Si1−x Ge x diodes are utilized as photodetectors that have a large output current under illumination. This paper elucidates the correlations between the structural, optical and electrical properties and the p–n junction performance of the film.
Keywords: Metastable SiGe; Rapid thermal annealing; High-resolution transmission electron microscopy; Nanocrystalline Ge;

A novel approach to fabricate high performance nano-SiO2 embedded PES membranes for microfiltration of oil-in-water emulsion by Mohammad Boshrouyeh Ghandashtani; Farzin Zokaee Ashtiani; Mohammad Karimi; Amir Fouladitajar (393-402).
The goal of this study was to determine the desired preparation conditions of polyethersulfone (PES) membrane for the microfiltration of oil-in-water emulsion. Membranes were fabricated via combination of vapor induced phase separation (VIPS) and non-solvent induced phase separation (NIPS) methods. SiO2 nanoparticle were used as the hydrophilicity modification agent in the casting solutions which led to a negative impacts on the permeate flux in high concentrations due to aggregation. The effects of nanoparticle concentration, exposure time and relative humidity on the permeate flux, and their interactions were determined. The morphology of the prepared membranes were studied using FESEM, pore size distribution, contact angle, porosity, and water uptake measurement. Besides, response surface methodology (RSM) and central composite design (CCD) were applied for modeling, statistical analysis and optimization of oil-in-water emulsion microfiltration. The most significant interactions were observed for the exposure time and relative humidity, and a contradictory trend was found for flux variation. The optimum preparation conditions for nanoparticle concentration, exposure time, and humidity were found to be 1%, 33 s, and 80%, respectively, where the oil rejection was higher than 98% for all runs.
Keywords: PES MF membrane; VIPS & NIPS; SiO2-nanoparticle; Oil-in-water emulsion;

Plasma nitriding of HP13Cr supermartensitic stainless steel by Bruna C.E.S. Kurelo; Gelson B. de Souza; Silvio L. Rutz da Silva; Francisco C. Serbena; Carlos E. Foerster; Clodomiro Alves (403-414).
Supermartensitic stainless steels (SMSS) are commonly employed in the oil exploitation industry and present a good balance between the necessary physical and chemical properties and financial costs. Certain applications, such as in extreme corrosive and abrasive environments, demand improvements in the surface properties of these steels. In the present work, HP13Cr SMSS with a fully martensitic microstructure were plasma nitrided in the 350–450 °C range. The high diffusivity and low solubility of nitrogen in the martensitic structure allowed the production of thick layers (16–61 μm) containing ɛ-Fe2–3N, γ′-Fe4N and expanded phase (αN) in all the temperatures. In addition, anisotropic sputtering rate and N-diffusion were observed for different grain orientations. Mechanical properties were measured by instrumented indentation, appropriately corrected from roughness effects on the results. Hardness profiles increased from 3.8 GPa (bulk) to ∼14 GPa (near surface region) in all the working temperatures, whereas the elastic modulus was 230 GPa, presenting no statistically significant differences with respect to the bulk value. Nanoscratch tests revealed a hardened-ductile like behavior of these nitride layers. The surface tribo-mechanical behavior was correlated with elastic–plastic responses of the precipitate-containing texturized layers. Results are interpreted in light of the effectiveness of plasma nitriding to modify the surface properties of SMSS.
Keywords: Plasma nitriding; Supermartensitic stainless steel; Surface; Hardness; Elastic modulus; Scratch test;

Uniform and defect-free silica films were prepared by spin-coating silica sols on plasma-treated hydrophobic sub-layers. Three kinds of silica films were prepared using tetraethoxysilane (TEOS), bis(triethoxysilyl)ethane (BTESE) and bis(triethoxysily)octane (BTESO) via sol–gel method. First, hydrophobic sub-layers were pre-coated on silicon wafers with Me-SiO2 sols prepared from mixtures of methyltrimethoxysilane (MTMS) and TEOS. After firing at 400 °C, the films showed water contact angles of 120°. Then TEOS- and BTESE-derived sols were directly spin-coated on the Me-SiO2 films, resulting in separated and scattered coatings. A H2O/N2 plasma modification method was used to change the properties of the Me-SiO2 films from hydrophobicity to hydrophilicity without damaging either the surface morphology or the bulk chemistry. After the treatment, the TEOS- and BTESE-derived sols formed homogenous films. On the other hand, the Me-SiO2 films were fully coated with BTESO either with or without plasma treatment. This was probably due to both the polar (–OH) and non-polar (long –CH2) portions of the BTESO-derived sols. For gas separation applications, the corresponding BTESE membranes showed great improvement in gas selectivity after the plasma treatment of hydrophobic Me-SiO2 layers.
Keywords: Organosilica; Hydrophobic; Plasma; Sol–gel technique; Gas separation; Spin-coating;

The formation of calcium phosphate coatings by pulse laser deposition on the surface of polymeric ferroelectric by E.N. Bolbasov; I.N. Lapin; V.A. Svetlichnyi; Y.D. Lenivtseva; A. Malashicheva; Y. Malashichev; A.S. Golovkin; Y.G. Anissimov; S.I. Tverdokhlebov (420-429).
This work analyses the properties of calcium phosphate coatings obtained by pulsed laser deposition on the surface of the ferroelectric polymer material. Atomic force and scanning electron microscopy studies demonstrate that, regardless of the type of sputtering target, the calcium phosphate coatings have a multiscale rough surface that is potentially capable of promoting the attachment and proliferation of osteoblasts. This developed surface of the coatings is due to its formation mainly from a liquid phase. The chemical and crystalline composition of the coatings depends on the type of sputtering target used. It was shown that, regardless of the type of sputtering target, the crystalline structure of the ferroelectric polymer material does not change. Cell viability and adhesion studies of mesenchymal stromal cells on the coatings were conducted using flow cytometry and fluorescent microscopy. These studies indicated that the produced coatings are non-toxic.
Keywords: Calcium phosphate coatings; Copolymer of vinilidene fluoride and tetrafluoroethylene; Pulse laser deposition; Hydroxyapatite; Monetite;

Synthesis of Cu2ZnSnS4 thin film through chemical successive ionic layer adsorption and reactions by Shuai Ma; Jing Sui; Lei Cao; Yang Li; Hongzhou Dong; Qian Zhang; Lifeng Dong (430-436).
By using successive ionic layer adsorption and reaction (SILAR) method, we provide for the first time comprehensive exploitation on experimental details regarding Cu2ZnSnS4 (CZTS) film deposition, including the optimization of precursor solution pH, buffer agent, reaction temperature, and annealing conditions. In particular, the investigation concerning the number of deposition cycles and annealing conditions and the manner in which they determine CZTS properties, such as surface morphology, crystallinity, film thickness, and energy bandgap, is emphasized. All of the above possess significance for CZTS film preparation, yet they are seldom reported systematically to our knowledge. Finally, we present a preliminary evaluation of the photoelectric performance of CZTS nanocrystal by a simple photoelectrochemical device configuration. Although the photoelectric properties of SILAR-deposited CZTS films await further improvement, current results regarding our experimental deposition are promising due to a fair trade-off between cost and its potential in photovoltaic applications.
Keywords: Thin films; Chemical synthesis; Electron microscopy; X-ray diffraction; Optical properties; Microstructure;

The hydrophilicity of a poly(ethylene terephthalate) (PET) fabric was greatly modified by using dilute sulfuric acid, which gradually became concentrated enough to sulfonate the fabric when microwave irradiation (MW) was applied. The modified PET fabric was super-hydrophilic. Modifying the fabric caused the water contact angle to decrease from 132.46 (for the unmodified fabric) to 0°, the water absorption rate to increase from 36.45 to 119.78%, and the capillary rise height to increase from 0.4 to 14.4 cm. The hydrophilicity of the modified PET fabric was not affected by washing it many times. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses showed that there were sulfonic acid groups on the modified fibers. Almost no difference between the surfaces of the unmodified and modified PET fibers was found using scanning electron microscopy. Analysis by differential scanning calorimetry showed that the unmodified and modified fabrics had similar thermostabilities. X-ray diffraction analysis of the crystalline structures of the unmodified and modified fibers showed that they were almost the same. The strength, elasticity, and rigidity of the unmodified fabric were retained by the modified fabric. The modified fabric had better dyeing properties than the unmodified fabric.
Keywords: Poly(ethylene terephthalate); Sulfuric acid; Sulfonation; Super-hydrophilic; Microwave irradiation;

The functional surface containing rich amino and hydroxyl groups was obtained by simple and easily dopamine self-polymerization. Poly (MPC) brushes were successfully immobilized on titanium surface by combining acylation reaction and ATRP. This chemical and biomimetic modified titanium surface effectively inhibits platelet adhesion and activation.Poly(2-methacryloyloxyethyl phosphorylcholine(MPC)) has been studied in many biomedical fields because of good biocompatibility, such as hemocompatibility, inhibiting protein adhesion, antifouling, and so on. To achieve good hemocompatibility of titanium (Ti) surface, bio-inspired poly(MPC) brushes were grafted from Ti substrate covalently. In this work, the surface of Ti was first coated with polydopamine, and got a surface bearing ―NH2 and ―OH groups which could be bridged with poly(MPC) via atom transfer radical polymerization. Water contact angle decreased to 51.3° when titanium grafted with poly(MPC) brushes. The data of Infrared Spectroscopy and X-ray photoelectron spectroscopy (XPS) indicated that poly(MPC) was successfully grafted onto the surface of titanium. Platelet-rich plasma (PRP) adhesion test and lactate dehydrogenase (LDH) assay showed that the number of platelets adhered on the surface of modified-titanium was much less than that of unmodified titanium and platelets did not aggregate and distort. Thus, the simple and chemical method of immobilization of poly(MPC) brushes has potential application for improving hemocompatibility for cardiovascular stent and some other biomaterials.
Keywords: Titanium substrate; Dopamine self-polymerization; 2-Methacryloyloxyethyl phosphorylcholine; Surface initiated ATRP; Anticoagulation;

Table-top deterministic and collective colloidal assembly using videoprojector lithography by J. Cordeiro; M. Zelsmann; T. Honegger; E. Picard; E. Hadji; D. Peyrade (452-458).
In the field of micro- and nanotechnology, most lithography and fabrication tools coming from the microelectronic industry are expensive, time-consuming and may need some masks that have to be subcontracted. Such approach is not suitable for other fields that require rapid prototyping such as chemistry, life science or energy and may hinder research creativity. In this work, we present two table-top equipments dedicated to the fabrication of deterministic colloidal particles assemblies onto micro-structured substrates. We show that, with a limited modification of the optics of a standard videoprojector, it is possible to quickly obtain substrates with thousands of micrometric features. Then, we combine these substrates with thermodynamic colloidal assembly and generate arrays of particles without defects. This work opens the way to a simple and table-top fabrication of devices based on colloidal particles.
Keywords: Maskless lithography; Videoprojector; Capillary force assembly; Colloidal assembly;

Photocatalytic degradation mechanisms of CeO2/Tb2O3 nanotubes by Narayanasamy Sabari Arul; Devanesan Mangalaraj; Tae Whan Kim (459-464).
CeO2/Tb2O3 nanotubes (NTs) have been synthesized using the surfactant free co-precipitation method. High resolution transmission electron microscopy (HRTEM) images, X-ray spectroscopy (XPS) spectra, and energy dispersive X-ray (EDAX) profiles showed that the as-synthesized samples were CeO2/Tb2O3 NTs. The photocatalytic activity of the synthesized catalysts was evaluated by degrading Methylene blue (MB) under visible light irradiation. The fitting of the absorbance maximum as a function of time showed that the photodegradation of the MB followed pseudo-first-order reaction kinetics. The estimated rate constants for the CeO2 NPs and the CeO2/Tb2O3 NTs were found to be 0.0134 and 0.0317 min−1, respectively. The photodegradation efficiency of CeO2/Tb2O3 nanotubes was 93% after 75 min, which was found to be higher than those of CeO2 NPs (66%).
Keywords: CeO2/Tb2O3; Nanotubes; Transmission electron microscopy; Methylene Blue; Photocatalyst;

A SiC nanowire-toughened SiC-ZrB2-ZrC coating was prepared on SiC-Si-coated carbon/carbon composites by a three-step process of pack cementation, electrophoretic deposition and pack cementation. The introduction of nanowires improved the oxidation resistance of SiC-ZrB2-ZrC coating, whose mass loss decreased from 4.49% to 0.27% after isothermal oxidation at 1500 °C for 210.5 h. Meanwhile, the thermal shock resistance of coating was improved significantly by introducing the nanowires, whose mass loss decreased from 11.13% to 0.52% after 30 thermal cycles between 1500 °C and room temperature. The nanowires could effectively alleviate the thermal stress generated from thermal shock and increase the toughness of coating, resulting in the decrease of crack sizes. Similar with the chemical vapor deposited SiC nanowires, the electrophoretically-deposited SiC nanowires could play positive role in enhancing the oxidation and thermal shock resistance of coating, attributing to the toughening mechanism including bridging and pullout of nanowires. As a fast and controllable technique, electrophoretic deposition of SiC nanowires could provide a more practical method to toughen coatings, which might have a broader prospect in practical applications.
Keywords: Carbon/carbon composites; SiC-ZrB2-ZrC coating; SiC nanowires; Oxidation resistance; Thermal shock resistance;

An improved Otsu method using the weighted object variance for defect detection by Xiao-cui Yuan; Lu-shen Wu; Qingjin Peng (472-484).
Defects on product surfaces affect quality of the product. Machine vision provides an efficient tool for the surface defect detection. Threshold is commonly used to separate objects from the image background in the vision-based inspection method. The Otsu method is one of the most used approaches to decide the threshold for a satisfied result when the image histogram is bimodal, but it fails when the histogram of an image is unimodal or close to unimodal. Defects in product surfaces can range from small to large sizes, which results in distributions of the image histogram change from unimodal to bimodal. An improved Otsu method, named the weighted object variance (WOV), is proposed in this research to detect defects on product surfaces. A parameter that equals the cumulative probability of defects occurrence is weighted on the object variance of between-class variance. The weight ensures that the threshold always be a value that locates at the valley of two peaks or at the left bottom rim of a single peak histogram. It is essential to have a high detection rate and low false alarm rate for the defect detection. Experimental results demonstrate the effectiveness of the improved Otsu method in the defect detection of various surfaces. Compared to other thresholding methods such as maximum entropy, Otsu, valley-emphasis, and modified valley-emphasis methods, the WOV method provides better segmentation results.
Keywords: Image segmentation; Otsu thresholding; Defects detection; Machine vision;

A new promising adsorbent, Ni supported on γ-Al2O3 was prepared in a simple electrolysis system (Ni/Al2O3-E) in minutes and was compared with the sample prepared by a physical mixing method (Ni/Al2O3-PM). The adsorbents were characterized by XRD, TEM, FTIR, 27Al MAS NMR, XPS, and VSM. The results showed that besides NiO nanoparticles, a NiAl2O4 spinel was also formed in Ni/Al2O3-E during the electrolysis via the dealumination and isomorphous substitution of Ni2+ ions. In contrast, only agglomerated NiO was found in the Ni/Al2O3-PM. Adsorption test on removal of Pd2+ ions from aqueous solution showed that the Pd2+ ions were exchanged with the hydrogen atoms of the surface–OH groups of both adsorbents. Significantly, the Ni/Al2O3-E demonstrated a higher adsorption towards Pd2+ ions than Ni/Al2O3-PM due to its remarkably higher degree of magnetism, which came from the NiAl2O4. The use of 0.1 g L−1 Ni/Al2O3-E gave the maximum monolayer adsorption capacity (q m) of 40.3 mg g−1 at 303 K and pH 5. The Ni/Al2O3-E showed high potential for simultaneous removal of various noble and transition metal ions and could be also used repetitively without affecting the high adsorptivity for Pd2+ ions. This work may provide promising adsorbents for recovery of various metals as well as other materials for such related applications.
Keywords: NiAl2O4 spinel; Electrosynthesis; Isomorphous substitution; Adsorption; Pd2+ ions;

A novel fluorochemical methacrylate monomer CH2 =C(CH3)CO(O)CH(CF2CF3)(CF(CF3)2) (2) containing short branched fluoroaliphatic groups is synthesized successfully from perfluoro ethyl isopropyl ketone. The homopolymer of 2 and copolymers of 2 and butyl methacrylate (BMA) with different fluorine contents are prepared. All the polymers have good thermal stability. A series of solutions of 3 wt% polymer in CCl2FCClF2 (R-113) are applied to clean coverslips. Properties of fluorinated polymer films are investigated. The results demonstrate that the homopolymer had excellent repellency properties which are slightly worse than that of polymers containing primarily straight-chain perfluorooctyl moieties but are better than that of polymers containing primarily straight-chain perfluorohexyl moieties. The water repellency decreases significantly when the fluorine content is less than 10% while the oil repellency decreases significantly when the fluorine content is less than 15%, thereby introducing BMA to copolymerize with 2 is a perfect method based on cost, solubility and performance standpoints.
Keywords: Fluorocarbon coating; Water and oil repellency; Fluorine-containing acrylate; Fluorine content; Free radical copolymerization;

Formation of reflective and conductive silver film on ABS surface via covalent grafting and solution spray by Dexin Chen; Yan Zhang; Takeshi Bessho; Takahiro Kudo; Jing Sang; Hidetoshi Hirahara; Kunio Mori; Zhixin Kang (503-509).
Conductive and reflective silver layers on acrylonitrile butadiene styrene (ABS) plastics have been prepared by photo grafting of triazine azides upon ultraviolet activation, self-assembling of triazine dithiols and silver electroless plating by solution spray based on silver mirror reaction. The as-prepared silver film exhibited excellent adhesion with ABS owing to covalent bonds between coating and substrate, and the detailed bonding mechanism have been investigated by X-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD) result revealed that silver film on ABS was pure and with a nanocrystalline structure. Atomic force microscope (AFM) analysis demonstrated that massive silver particles with sizes varying from 80 to 120 nm were deposited on ABS and formed a homogenous and smooth coating, resulting in highly reflective surface. Furthermore, silver maintained its unique conductivity even as film on ABS surface in term of four-point probe method.
Keywords: ABS; Reflective; Conductive; Covalent grafting; Solution spray;

The structural and electronic properties of the bulk and low-index (0 0 1) and (1 1 0) surfaces of the MnCo2O4 spinel have been studied from the spin-polarized GGA + U calculations. Results show that Mn prefers to occupy the octahedral sites and exhibits as high-spin Mn3+ while half Co takes the tetrahedral sites as high-spin Co2+ and the other half takes the octahedral sites as nonmagnetic Co3+. The electronic structure of the MnCo2O4 bulk is insulating with very small gap of about 0.03 eV. The surface atomic relaxations and surface energies are calculated with different terminations and stable MnCo2O4 (0 0 1) and (1 1 0) surface models are obtained. The electronic structures of the Mn and the tetrahedral site Co atoms at the MnCo2O4 (0 0 1) and (1 1 0) surfaces resemble their bulk characters. However, due to the lowered Co–O coordination, the electronic structure of the octahedral Co atoms changes substantially from the bulk state t3 2g(↑)t3 2g(↓) into the surface state t3 2g(↑)e1 g(↓) t2 2g(↓) at the MnCo2O4 (0 0 1) surface (5-coordinated Co) and t3 2g(↓)e2 g(↓)t1 2g(↓)e1 g(↓) at the MnCo2O4 (1 1 0) surface (4-coordinated Co).
Keywords: MnCo2O4; Surface electronic structure; Inverse spinel;

In this paper, a simple method for fabricating tunable adhesion superhydrophobic surface based on heterogeneous chemical composition was reported. By simply changing the ratio of HOOC(CH2)8COOH in the mixed modification solution, the slide angles (SA) of water droplet can be adjusted from extremely low (less than 10°) to very high (180°). Besides, the influence of surface chemical composition on the surface adhesion was also examined. Noticeably, the anti-corrosion performance of magnesium alloy was greatly improved after being modified. In addition, the tunable adhesion superhydrophobic magnesium alloy showed high hydrophobicity not only for pure water but also for corrosive liquids, such as acid, alkali, salt, cola, milk and coffee. Based on the great anti-corrosion performance and continuous adhesion, a proof of droplet-based microreactor and selective transportation of waters with different volume was provided. This study provides a new method for preparation of superhydrophobic surfaces with tunable adhesion, which not only offers the further principle for the fabrication of tunable adhesive superhydrophobic surfaces, but also can be potentially used in many important applications, such as micro-fluidic devices and chemical microreactors.
Keywords: Superhydrophobic surface; Adhesion controllable; Micro-droplet reactor;

Effects of interfacial Fe electronic structures on magnetic and electronic transport properties in oxide/NiFe/oxide heterostructures by Qianqian Liu; Xi Chen; Jing-Yan Zhang; Meiyin Yang; Xu-Jing Li; Shao-Long Jiang; Yi-Wei Liu; Yi Cao; Zheng-Long Wu; Chun Feng; Lei Ding; Guang-Hua Yu (524-528).
We report that the magnetic and electronic transport properties in oxide/NiFe(2 nm)/oxide film (oxide = SiO2, MgO or HfO2) are strongly influenced by the electronic structure of NiFe/oxide interface. Magnetic measurements show that there exist magnetic dead layers in the SiO2 sandwiched film and MgO sandwiched film, whereas there is no magnetic dead layer in the HfO2 sandwiched film. Furthermore, in the ultrathin SiO2 sandwiched film no magnetoresistance (MR) is detected, while in the ultrathin MgO sandwiched film and HfO2 sandwiched film the MR ratios reach 0.35% and 0.88%, respectively. The investigation by X-ray photoelectron spectroscopy reveals that the distinct interfacial redox reactions, which are dependent on the oxide layers, lead to the variation of magnetic and transport properties in different oxide/NiFe/oxide heterostructures.
Keywords: NiFe/oxide interface; Interfacial electronic structure; X-ray photoelectron spectroscopy; Electronegativity; Magnetotransport;

m-BiVO4@CeO2 hollow microspheres have been fabricated by a facile low-temperature co-precipitation method and subsequent annealing process. The composition, morphology and size of the as-fabricated m-BiVO4@CeO2 hollow microspheres were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The vibrational features and the electronic state of the as-obtained m-BiVO4@CeO2 hollow microspheres were studied by Raman spectra and X-ray photoelectron spectroscopy (XPS). Band-gap energy of the as-prepared m-BiVO4@CeO2 hollow microspheres was evaluated by UV–vis spectrum. The visible-light-driven photocatalystic performances were evaluated by degradation for RhB dye molecules, demonstrating that the as-fabricated m-BiVO4@CeO2 hollow microspheres exhibit the enhanced photocatalystic activity, compared to the obtained pure m-BiVO4 microspheres. The separation of photoinduced electron–hole pairs and transfer between CeO2 and BiVO4 has been discussed in detail, in order to have in-depth understanding on the enhanced photocatalytic performance. The results indicate that the enhanced photocatalystic activity of the as-fabricated m-BiVO4@CeO2 hollow microspheres is attributed to the efficient separation of the photoexcited electrons and holes.
Keywords: Microspheres; Degradation; Photocatalysis; Preparation; m-BiVO4@CeO2 hollow microspheres;

Mineralization on polylactide/gelatin composite nanofibers using simulated body fluid containing amino acid by Yougang Guo; Jinle Lan; Caijin Zhang; Man Cao; Qing Cai; Xiaoping Yang (538-548).
From physiological point of view, organic–inorganic composite nanofibers are envisioned promising substrates for bone tissue engineering. Biomineralization on polymeric nanofibers using simulated body fluid (SBF) is a common technique to obtain the composite nanofibers. Many factors, however, will affect the nucleation and crystal growth of deposited apatite, such as the additives like amino acids in SBF. In this study, electrospun composite nanofibers consisting of poly(l-lactide) (PLLA, 50 wt%) and gelatin (50 wt%) were soaked in 2.5 times SBF (2.5SBF) for different time periods (1, 2, 3, 5 and 7 days) to perform the biomineralization. Three amino acids (glycine, aspartic acid, or arginine) of different charge characteristics were introduced into the SBF, and their effects on nucleation and transformation of calcium phosphate depositions were systematically investigated. The results revealed that amino acids could take part in the early stage formation of pre-nucleation clusters, leading to different assemblies dependent closely on the feature of amino acid. In comparison with normal 2.5SBF, the presence of amino acid was able to enhance the preferred orientation of hydroxyapatite (HA) crystal along c axis and the transformation from amorphous calcium phosphate to hierarchical HA. The incorporation of glycine had promoted the formation of the well-evolved needle-like HA crystals in comparison with aspartic acid or arginine. It was suggested that the addition of amino acids into SBF might be a useful tool to regulate the biomineralizaiton for preparing organic–inorganic composite nanofibers.
Keywords: Amino acid; Biomineralization; Simulated body fluid; Nucleation;

The pure ZnO and Al-doped ZnO (AZO) thin films (thickness: 200 nm) were prepared on both side polished silica (SiO2) substrates via RF magnetron sputtering at room temperature by using 2.5 inches high-purity ZnO (99.9%) and Al (99.9%) targets. The samples were annealed at 300 °C, 400 °C and 500 °C for 45 min in N2 ambient in quartz annealing furnace system, respectively. We investigated the effects of various Al concentrations and annealing treatment on the structural, electrical, and optical properties of films. The preferred crystallization was observed along c axis (single (0 0 2) diffraction peak) from substrate surface assigning the single crystalline Würtzite lattice for pure ZnO and AZO thin films. Although increasing Al concentration decreases the order of crystallization of as-grown films, annealing process increases the long range crystal order. The crystallite sizes vary between minimum 12.98 nm and maximum 20.79 nm for as-grown and annealed samples. The crystallite sizes decrease with increasing Al concentration but increase with increasing annealing temperature as general trend. The grain size and porosity of films change with annealing treatment. The smaller grains coalesce together to form larger grains for many films. However, a reverse behavior is seen for Al2.23ZnO and Al12.30ZnO samples. That is, Al concentration plays critical role as well as temperature on grain size. Low percent optical transmittance (T%) is observed due to higher Al concentration and worse crystal quality for as-grown AZO films. T% decreases until 34.5% for as-grown Al15.62ZnO film. T% increases by increasing annealing temperature. AZO samples annealed at 500 °C have around 80% transparencies in the visible range of spectrum. Optical energy band gap values range between 3.17 eV and 3.60 eV for as-grown and annealed samples. Band gap increments are attributed to increasing free electron concentration depending on doped Al ratio known as Burstein–Moss effect. Annealing process increases the band gap values, too. The electrical conductivity and carrier concentration of the films increased with increasing Al content. The mobility decreases due to increase in Al concentration that deteriorates the crystal nature. Annealing process especially at 400 °C enables the AZO samples to exhibit best electric conductivity due to long range crystal structured nature and increasing free electron concentration in the films. The maximum electrical conductivity value of 1.06 × 104  (Ωcm)−1 was measured from Al12.30ZnO sample annealed at 400 °C.
Keywords: AZO; RF magnetron sputtering; Optical and electrical properties;

Bioglass/TiO2 nanocomposites were coated on to the surface of etched CP-Ti substrate. The surface of the coatings were further covered with Bioglass fibres to enhance the rate of hydroxy carbonate apatite and osseointegration during implant applications.We demonstrate an approach for Bioglass/TiO2 nanocomposites coatings onto the TiO2 nano-surfaces formed by etching of CP-Ti. The coated surface is further covered with Bioglass fibres to enhance the rate of apatite formation. Different concentrations of Bioglass/TiO2 composites are prepared by changing the TiO2 concentration. The coating is performed by electrophoretic deposition technique, and it shows less concentration of TiO2 gives higher adhesion to the substrates. The in vitro electrochemical corrosion and immersion studies confirm that the lower concentrations of TiO2 containing Bioglass/TiO2 composites coated sample possesses higher corrosion resistance and bio-mineralization that is highly suitable for bone osseointegration applications.
Keywords: Bioglass; TiO2; Fibres; Electrochemical corrosion; Biomineralization; Multilayer coating;

One-step synthesis of high conductivity silver nanoparticle-reduced graphene oxide composite films by electron beam irradiation by Gang Liu; Yujia Wang; Xianjuan Pu; Yong Jiang; Lingli Cheng; Zheng Jiao (570-575).
A rapid, eco-friendly, one-step electron beam (EB)-based method for both the reduction of graphene oxide and loading of Ag nanoparticles (AgNPs) were achieved. Further, the effects of irradiation dose on the morphology of AgNPs and the sheet resistance of Ag nanoparticles/reduced graphene oxide (AgNPs/rGO) were studied. The results reveal that when the irradiation dose increased from 70 kGy to 350 kGy, the size of the AgNPs decreased and became uniformly distributed over the surface of the rGO nanosheets. However the size of the AgNPs increased when the irradiation dose reached 500 kGy. Four-point probe measurement showed that the sheet resistance of the AgNPs/rGO films decreased with decreasing AgNPs size. The lowest sheet resistivity of 0.06 Ω m was obtained in the film corresponding to 350 kGy irradiation dose, which showed a much lower resistivity than the GO film (5.04 × 105  Ω m). The formation mechanisms of the as-prepared AgNPs/rGO nanocomposites were proposed. This study provides a fast and eco-friendly EB irradiation induced method to controlling the dimensions of AgNPs/rGO nanocomposites, which can strongly support the mass production of AgNPs/rGO nanocomposites for practical applications.
Keywords: Silver nanoparticles; Reduced graphene oxide; Electron beam irradiation; Dimension controlled; Electrical property;

Influence of substrate on nucleation and growth of vertical graphene nanosheets by Subrata Ghosh; K. Ganesan; S.R. Polaki; Tom Mathews; Sandip Dhara; M. Kamruddin; A.K. Tyagi (576-581).
The present study reports the role of substrate on nucleation and growth of vertical graphene nanosheets (VGNs) under electron cyclotron resonance chemical vapor deposition (ECR-CVD). The VGNs are grown on Pt, Ni, Au, Cu, Si(100), Si(111), SiO2 and quartz substrates simultaneously. The morphology of VGNs is found to vary significantly with substrate. VGNs on Pt have the highest aerial density of vertical sheets while quartz have the lowest. The structural defects in VGNs vary with substrate as evidenced from Raman spectroscopy. The observation of defect related Raman bands such as D″ and D* at 1150 and 1500 cm−1, respectively revealed the existence of pentagon–heptagon rings or carbon onions in VGNs. Formation of such defects at early stage of nucleation dictates the growth mechanism and hence the morphology. A phenomenological four-stage model is discussed, to substantiate the nucleation and growth mechanism of VGNs on different substrates, by evoking substrate–plasma interaction during growth.
Keywords: Vertical graphene nanosheets; ECR-CVD; Raman spectroscopy; SEM; Nucleation;

Characterization of polymeric thin films for photovoltaic applications by spectroscopic ellipsometry by V. Schmiedova; P. Heinrichova; O. Zmeskal; M. Weiter (582-588).
The article deals with determination of complex refractive indexes of organic thin films; the assessment was implemented by spectroscopic ellipsometry. Thin films of π-conjugated MDMO-PPV, PCDTBT, and PCBTDPP polymers blended with PC60BM and PC70BM fullerenes were subjected to investigation. Recently, these materials have intensively been studied for their potential application in photovoltaics. This article summarizes research findings on refractive indexes and extinction coefficients of the above studied pure materials and their mixtures. The obtained ellipsometric data were evaluated according to the Tauc–Lorentz model.
Keywords: Organic materials; Spectroscopic ellipsometry; Solar cells; UV–vis absorption; Profilometry;

Vascular cell responses to ECM produced by smooth muscle cells on TiO2 nanotubes by Fangyu Shen; Ying Zhu; Xin Li; Rifang Luo; Qiufen Tu; Jin Wang; Nan Huang (589-598).
There is an increasing interest in developing new methods to promote biocompatibility of biomedical materials. The TiO2 nanotubes with the tube diameter of 30 nm were prepared by anodization. The response behavior of the human umbilical vein endothelial cell (HUVEC) and human umbilical artery smooth muscle cell (HUASMC) to these different nanotube sizes was investigated. Compared to the flat Ti, the growth and viability of HUVEC are prohibited, but there was no significant difference of HUASMC on 30 nm TiO2 nanotubes. In this study, extracellular matrix (ECM) as a complex cellular environment which provides structural support to cells and regulates the cells functions was further used to modify the biological properties of TiO2 nanotubes. The ECM secreted from HUASMC was successfully deposited onto the 30 nm TiO2 nanotubes. Moreover, immunofluorescence staining of common ECM components, such as fibronectin, laminin and type IV collagen, also indicated the successful ECM-covering on nanotube surfaces. Interestingly, the surface of ECM-covered TiO2 nanotubes significantly improved the proliferation of HUVECs in vitro. This suggested that the ECM secreted from HUASMCs on the TiO2 nanotubular surface could further improve the HUVECs adhesion and proliferation.
Keywords: TiO2 nanotube; Extracellular matrix; Biocompatibility; Endothelial cell; Smooth muscle cell;

The combined action of UV irradiation and chemical treatment on the titanium surface of dental implants by Silvia Spriano; Sara Ferraris; Daniele Bollati; Marco Morra; Clara Cassinelli; Giorgio Lorenzon (599-608).
The purpose of this paper is to describe an innovative treatment for titanium dental implants, aimed at faster and more effective osteointegration.The treatment has been performed with the use of hydrogen peroxide, whose action was enhanced by concomitant exposure to a source of ultraviolet light. The developed surface oxide layer was characterized from the physical and chemical points of view. Moreover osteoblast-like SaOS2 cells were cultured on treated and control titanium surfaces and cell behavior investigated by scanning electron microscope observation and gene expression measurements.The described process produces, in only 6 min, a thin, homogeneous, not porous, free of cracks and bioactive (in vitro apatite precipitation) oxide layer. High cell density, peculiar morphology and overexpression of several genes involved with osteogenesis have been observed on modified surfaces.The proposed process significantly improves the biological response of titanium surfaces, and is an interesting solution for the improvement of bone integration of dental implants. A clinical application of the described surfaces, with a 5 years follow-up, is reported in the paper, as an example of the effectiveness of the proposed treatment.
Keywords: Dental implants; Titanium; Photoactivated oxidation; Osteoblasts; Osteogenesis;

Plasma-induced formation of flower-like Ag2O nanostructures by Zen-Hung Yang; Chun-Hsien Ho; Szetsen Lee (609-614).
Flower-like Ag2O nanostructures.Plasma treatment effect on Ag colloids was investigated using X-ray photoelectron spectroscopy (XPS) and surface-enhanced Raman scattering (SERS) techniques. XPS showed that O2 plasma was critical in removing organic residues in Ag colloids synthesized using citric acid as a reducing agent. With O2 plasma treatment, Ag colloids were also oxidized to form flower-like Ag2O nanostructures. The formation mechanism is proposed. The SERS spectral intensity of methyl orange (MO) adsorbed on Ag surface became deteriorated with O2 plasma treatment. Followed by H2 plasma treatment, the SERS intensity of MO on Ag regained, which indicated that Ag2O has been reduced to Ag. Nonetheless, the reduction by H2 plasma could not bring Ag back to the original as-synthesized nanoparticle morphology. The flower-like nanostructure morphology still remained. The photocatalytic degradation reactions of methylene blue (MB) aqueous solutions were carried out using Ag colloids and Ag2O nanostructures. The results show that Ag2O is more efficient than Ag colloids and many other metal oxides for the photocatalytic degradation of MB in solution when utilizing visible light.
Keywords: Ag colloids; Ag2O; Plasma; SERS; Photocatalytic degradation;

Doping effect of In2O3 on structural and ethanol-sensing characteristics of ZnO nanotubes fabricated by electrospinning by Baoyu Huang; Changhui Zhao; Mingxiang Zhang; Zemin Zhang; Erqing Xie; Jinyuan Zhou; Weihua Han (615-621).
Indium-doped ZnO (IZO) nanotubes with various indium contents (0.01–0.20) were synthesized via a facile electrospinning method. Results of X-ray diffraction and transmission electron microscopy demonstrate that all samples are consisted of hexagonal wurtzite-typed ZnO, showing a well-crystallized indium-zinc-oxide solid solution when only a small amount of zinc ions substituted by indium ions (0.01). Once the amount of indium dopants ≥0.05, there will form some amorphous In2O3, leading to a pronounced decrease in grain sizes. Gas-sensing performances revealed that the IZO nanotube-based sensors have enhanced ethanol-sensing characteristics, especially, sensor based on IZO-0.01 nanotubes shows the highest response (R a/R g  = 81.7), which is twice that of the undoped ZnO nanotubes (40.0) toward 100 ppm ethanol at an operating temperature of 275 °C. And IZO-0.20 nanotube-based sensor presents a relatively high response at high ethanol concentrations. Our research suggested that these remarkable enhanced ethanol-sensing properties can be closely related to the formation of indium-zinc-oxide solid solutions and/or heterostructures between ZnO and amorphous In2O3.
Keywords: ZnO nanotubes; In2O3; Electrospinning; Ethanol; Gas sensors;

Characterization and identification of minerals in rocks by ToF-SIMS and principal component analysis by Stefan Rinnen; Christiane Stroth; Andreas Riße; Christian Ostertag-Henning; Heinrich F. Arlinghaus (622-628).
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to characterize and identify minerals in rock samples. ToF-SIMS provides a vast amount of information due to the recording of complete mass spectra with elemental and molecular ion signals. For an efficient handling of this amount of data multivariate analysis (MVA) techniques are useful tools. Initially principal component analysis (PCA) was implemented to classify 20 well-defined reference minerals. In a second step the spectra data of undetermined minerals in rock samples were projected on the PCA models to identify these mineral species. Hereby the data sets of positive and negative ion signals were used separately. It was possible to classify the reference minerals and identify mineral species in rock samples. Furthermore it was found that minerals not contained in the reference set were not misidentified.
Keywords: ToF-SIMS; Minerals; Geology; PCA; Classification; Identification;

High-activity electrodeposited NiW catalysts for hydrogen evolution in alkaline water electrolysis by Sung Hoon Hong; Sang Hyun Ahn; Jihui Choi; Jin Yeong Kim; Ho Young Kim; Hyoung-Juhn Kim; Jong Hyun Jang; Haekyoung Kim; Soo-Kil Kim (629-635).
NiW alloy catalysts were prepared on a Cu foil substrate by using a co-electrodeposition method for use in the hydrogen evolution reaction (HER) in alkaline water electrolysis. The compositions of the alloy catalysts were controlled over a wide range by varying the molar ratio [W6+]/[Ni2+] in the electrolyte. At high W contents (∼41 at.%) in the deposited catalyst, the morphologies of the NiW alloys showed drastic changes compared with those of electrodeposited Ni, in particular a significant decrease in surface coverage and aggregates’ sizes. All of NiW alloys deposited in a citrate-containing bath demonstrated an amorphous structure, regardless of W content. Electrochemical measurements employing repeated cyclic voltammetry (CV) showed enhanced HER activities for the NiW alloy catalysts compared with the pure Ni catalyst. The maximum HER activity was obtained with a W content of 41 at.%; the alloying effects, including morphological changes, and the high affinity for hydrogen absorption shown by this alloy's amorphous structure are dominant factors in the enhanced HER activity. The results presented herein provide advanced information of significant relationship between material properties and HER activity of NiW alloys.
Keywords: Alkaline water electrolysis; Hydrogen evolution reaction; Alloy deposition; Amorphous nickel tungsten alloy catalyst;

Controllable fabrication of nanowire-like CuO film by anodization and its properties by Yongqian Wang; Tingting Jiang; Dawei Meng; Hongyun Jin; Meihua Yu (636-643).
We report a simple electrochemical etching and a subsequent heat treatment to synthesize nanowire-like CuO thin films with pure phase at room temperature. The reaction media has great effect on microstructure of products to significantly improve optical and photocatalytic activities of materials. Detailed characterizations of the synthesized nanomaterials are performed utilizing X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) to study their crystalline phase and morphology. The photoluminescence (PL) spectrum shows a main emission peak and a blue emission band whose centers are located at 352 nm and 463 nm, respectively. Photocatalytic study demonstrated the degradation of methylene blue (MB) can reach 95.6% after 210 min irradiation, showing its potential application in waste water treatment. A plausible growth mechanism for the transformation is also proposed.
Keywords: CuO nanowires; Anodization; Photocatalytic activity; Growth mechanism;

Li ion batteries and its accessories are now under increased focus of research due to enhanced energy storage and recycling requirements and the need for clean environments. In this context, observations on Li battery electrodes prepared using multi-wall carbon nanotubes (MWCNT) coated on stainless steel as observed by time of flight secondary ion mass spectrometry (TOF-SIMS) analysis and their relevance in understanding and improving the electrochemical properties of such battery systems are discussed. Porosity issues due to MWCNT, and accumulation of chemical residues with operational cycles were observed, their possible causes were also analyzed and discussed. Issues on change in electrode performance due to usage of tin oxide coatings on the MWCNT were also compared and analyzed.
Keywords: Polymers; Li battery; TOF-SIMS; Ion imaging;

Study on stability of poly(3-hexylthiophene)/titanium dioxide composites as a visible light photocatalyst by Jianling Zhang; Shaoqiang Cao; Shoubin Xu; Haigang Yang; Long Yang; Yuanqing Song; Long Jiang; Yi Dan (650-656).
Conjugated polymer/TiO2 composites are promising visible light photocatalysts for solar chemical conversion processes in the field of environmental chemistry for decomposition of organic compounds in water and air. In consideration of the fact that conjugated polymers are also organic substances, particular attention must be focused on the stability of conjugated polymer/TiO2 composites, which has not been laid enough emphasis upon so far. Poly(3-hexylthiophene)/titanium dioxide (P3HT/TiO2) composites, as a representative of conjugated polymer/TiO2 photocatalysts, were prepared by combining chemical oxidative polymerization method and physical blending technique. The stability of the composites was systematically studied by comparative analysis of the physical and chemical structure of P3HT/TiO2 composites before and after the photocatalytic reaction. As confirmed by the results of high-resolution transmission electron microscopy (HRTEM), scanning electron microscope (SEM), ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the P3HT/TiO2 composites were quite stable to 10 h of photodegradation of methyl orange (MO) under visible light, maintaining both their physical and chemical structure.
Keywords: P3HT/TiO2 composites; Visible light photocatalyst; Stability; Conjugated polymer/TiO2;

The surface enhanced Raman scattering (SERS) is a highly surface sensitive technique to study inter-surface properties of biological, organic, and inorganic materials. It is a precise technique to determine the adsorption geometry/orientation of the molecules as the intensity enhancement of the SERS bands depends on the adsorption geometry/orientation of molecules on SERS substrate. In the present work, Ni, Cu and Zn complexes of (Z)-N′(1,3,4-thiadiazol-2-yl) acetimidate were synthesized and adsorbed on ZnO nanoparticles. The surface enhanced Raman scattering (SERS), UV–vis and DFT techniques were applied to investigate the possible adsorption geometries of the complexes on ZnO. Consequently, it was found that the orientation of all three complex molecules is flat-on onto the surface of ZnO nanoparticles. The fluorescence background of Raman spectra of Zn complex is quenched and its geometry is isomerized after the adsorption onto the surface of ZnO nanoparticles. The adsorbed Cu complex on ZnO NPs absorbed UV radiations efficiently.
Keywords: Surface enhanced Raman scattering (SERS); UV–vis; Density functional theory; Coordination complex molecules; ZnO nanoparticles;

Coordination-resolved local bond strain and 3p energy entrapment of K atomic clusters and K(1 1 0) skin by Ting Zhang; Maolin Bo; Yongling Guo; Hefeng Chen; Yan Wang; Yongli Huang; Chang Q. Sun (665-672).
We have examined the atomic coordination effect on the local bond strain and the 3p core-level shift of K(1 1 0) skin and nanoclusters using a combination of the bond order–length–strength correlation notion, tight-binding approach, density functional theory calculations, and photoelectron spectroscopy measurements. It turns out that: (i) the 3p core-level shifts from 15.595 ± 0.003 eV for an isolated K atom by 2.758 eV to the bulk value of 18.353 eV; (ii) the effective atomic coordination number reduces from the bulk value of 12 to 3.93 for the first layer and to 5.81 for the second layer of K(1 1 0) skin associated with the local lattice strain of 12.76%, a binding energy density 72.67%, and atomic cohesive energy −62.46% for the skin; and (iii) K cluster size reduction lowers the effective atomic coordination number and enhances further the skin electronic attribution. Results have revealed that the 3p core-level shifts of K(1 1 0) and nanoclusters originate from perturbation of the Hamiltonian by under-coordination induced charge densification and quantum entrapment.
Keywords: K nanoclusters and solid skin; XPS; DFT; BOLS; Energy entrapment;

Highly-conformal p-type copper(I) oxide (Cu2O) thin films by atomic layer deposition using a fluorine-free amino-alkoxide precursor by Hangil Kim; Min Young Lee; Soo-Hyun Kim; So Ik Bae; Kyung Yong Ko; Hyungjun Kim; Kyeong-Woo Kwon; Jin-Ha Hwang; Do-Joong Lee (673-682).
A highly-conformal and stoichiometric p-type cuprous copper(I) oxide (Cu2O) thin films were grown using atomic layer deposition (ALD) by a fluorine-free amino-alkoxide Cu precursor, bis(1-dimethylamino-2-methyl-2-butoxy)copper (C14H32N2O2Cu), and water vapor (H2O). Among tested deposition temperatures ranging from 120 to 240 °C, a self-limited film growth was clearly confirmed for both precursor and reactant pulsing times at 140 °C. Between 140 and 160 °C, the process exhibited an almost constant growth rate of ∼0.013 nm/cycle and a negligible number of incubation cycles (approximately 6 cycles). The Cu2O films deposited at the optimal temperature (e.g. 140 °C) showed better properties in view of their crystallinity and roughness compared to the films deposited at higher temperatures. Rutherford backscattering spectrometry showed that the film deposited at 140 °C was almost stoichiometric (a ratio of Cu and O ∼2: 1.1) with negligible C and N impurities. X-ray photoelectron spectroscopy further revealed that Cu and O in the film mostly formed Cu2O bonding rather than CuO bonding. Plan-view transmission electron microscopy analysis showed formation of densely packed crystal grains with a cubic crystal structure of cuprous Cu2O. The step coverage of ALD-Cu2O film was remarkable, approximately 100%, over 1.14-μm-high Si nanowires with an aspect ratio (AR) of 7.6:1 and onto nano-trenches (top opening width: 25 nm) with an AR of 4.5:1. Spectroscopic ellipsometry was employed to determine optical constants, giving optical direct band gap of 2.52 eV. Finally, Hall measurement confirmed that the ALD-Cu2O film had p-type carriers with a high Hall mobility of 8.05 cm2/V s.
Keywords: Cu2O thin films; Atomic layer deposition; p-Type semiconductor; Conformality;

Self-assembled monolayers of perfluoroalkylsilane on plasma-hydroxylated silicon substrates by Lin Wu; Lu Cai; Anqi Liu; Wei Wang; Yanhua Yuan; Zhanxiong Li (683-694).
In this study, a novel kind of fluoroalkylsilane monomers with different fluoroalkyl chain lengths was synthesized via three steps method and characterized by Fourier transform infrared (FT-IR) spectroscopy, 1H and 19F nuclear magnetic resonance (1H NMR and 19F NMR), and mass spectra (MS). Fluoroalkyl-terminated self-assembled monolayers (SAMs) on silanol-terminated silicon substrates (O2 plasma treatment) were chemically fabricated via –Si–O– covalent bonds using the liquid phase deposition method (LPD). The wetabilities of the SAMs were characterized by water contact angles (CA), surface free energies and adhesive force (AF) measurements. 3-(1H,1H,2H,2H-perfluorooctyloxycarbonyl)-propionamidepropyl-triethoxysilane (PFOPT) assembled monolayer was chosen for in-depth investigation as its CA was higher than the others. Attenuated total reflection infrared spectroscopy (ATR-IR) and X-ray photoelectron spectroscopy (XPS) were used to validate the attachment of PFOPT on the silicon substrate, together with the chemical composition and structure of the SAMs. The surface morphologies and roughness of the monolayers were obtained and calculated through atomic force microscopy (AFM). The migration of fluoroalkyl groups to the outermost surface of the SAMs was confirmed by AFM, XPS, CA, and AF measurements. It was found that the silicon substrate assembled with fluoroalkylsilane after heat treatment has higher contact angle, lower surface energy and adhesive force compared to that without heat treatment, and the outermost surface was rich in fluorine due to the surface microphase separation.
Keywords: Self-assembled monolayer; Perfluoroalkylsilane; Microphase separation; Surface modification;

Controlled in situ formation of polyacrylamide hydrogel on PET surface via SI-ARGET-ATRP for wound dressings by Sedigheh Nazari Pour; Shivkumar V. Ghugare; Richard Wiens; Kathleen Gough; Song Liu (695-704).
Well-defined polyacrylamide (PAM) hydrogel was synthesized on the surface of poly(ethylene terephthalate) (PET) film via surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET-ATRP). Following the deposition of an ATRP initiator (2-bromoisobutyrylbromide) on PET film, PAM hydrogel was grafted from the functionalized PET surface via ARGET-ATRP. XPS and FTIR-ATR confirmed that PAM hydrogel was successfully grafted on the PET surface. Results from AFM, SEM, and FTIR-FPA microscopic investigations showed that PAM hydrogel uniformly covers the surface of PET film. The grafting yield increases linearly with increasing reaction time, indicating that the growth of PAM hydrogel on the surface of PET is well controlled. In a cell adhesion assay, PAM hydrogel grafted PET films (PAM hydrogel-g-PET) showed low adhesion to keratinocyte cells. To impart PAM hydrogel-g-PET with antibacterial function, AgNPs were self-assembled along the amide side chains of PAM hydrogel. AgNPs loaded-PAM hydrogel-g-PET shows 99% reduction in the number of multidrug-resistant Pseudomonas aeruginosa within 3 h contact.
Keywords: ARGET-ATRP; Polyacrylamide; Hydrogel; Surface modification; Antibacterial; Wound dressing;

Microbumpers maintain superhydrophobicity of nanostructured surfaces upon touch by I.D. Jung; M.C. Lee; H. Lim; E. Smela; J.S. Ko (705-714).
Because of their fragility, nanostructured surfaces have not been used in applications that require mechanical contact with the environment. This paper demonstrates the utility of an array of “microbumpers” in the form of pillars rising above a nanostructured surface to provide protection. Superhydrophobic surfaces with micro-pillar arrays of varying pitch were fabricated and subjected to repeated vertical touch with a PDMS finger replica under different applied forces, such as would be experienced by a touch screen display. For sufficiently small pitches, the microbumpers maintained the strong water repellency and low droplet adhesion, even after 1000 touch cycles, but if the pitch was too large the nanostructures were damaged and the superhydrophobicity lost. In comparison, surfaces comprising only nanostructures lost superhydrophobicity almost immediately. To image surface wetting by the water droplets, a droplet freeze-fixing, resin-embedding (FFRE) technique was developed. The approach of decorating a surface with microbumpers to provide mechanical protection should be applicable to a wide range of substrates with coatings optimized for various functions.
Keywords: Surface micromachining; Electroplating; Electroless plating; Plasma-polymerized fluorocarbon; Touch test; Contact angle hysteresis;

Superhydrophobic laser ablated PTFE substrates by Salma Falah Toosi; Sona Moradi; Saeid Kamal; Savvas G. Hatzikiriakos (715-723).
The effect of femtosecond laser irradiation process parameters (fluence, scanning speed and beam overlap) on the wettability of the resulted micro/nano-patterned morphologies on polytetrafluoroethylene is studied in detail. Several distinctly different micro/nano-patterns were fabricated including uniaxial and biaxial patterns. In particular, using biaxial scanning well defined pillared morphology was fabricated. The wettability analysis of the biaxially scanned samples revealed enhanced superhydrophobicity exhibiting high contact angles and low contact angle hysteresis.
Keywords: Superhydrophibicity; Laser ablation; Micro/nano pattern; Surface wettability; Contact angle hysteresis; Polytetrafluoroethylne;

Superhydrophobicity is extensively investigated because of the numerous methods developed for water-repellant interface fabrication. Many suitable functional materials for the production of superhydrophobic surfaces on various substrates are still being explored. In this study, inorganic SiO2 and organic polytetrafluoroethylene (PTFE) nanoparticles (NPs) are used for a comparative study on the performance of superhydrophobic coating on carbon steel surfaces. The NPs are added to PTFE coating emulsions by physical blending to form coating mixtures. Raw SiO2 NPs are then hydrophobized using KH-570 and validated by Fourier transform-infrared spectroscopy (FT-IR) and Dynamic Laser Scattering (DLS) grain size analyses. The microstructures of the surfaces are characterized by contact angle (CA) measurements and field emission-scanning electron microscope (FE-SEM) images. The prepared surfaces are subjected to adhesion, hardness, water resistance, and acid/alkali erosion tests. Hydrophobized SiO2-filled coating surfaces are found to have better uniformity than raw SiO2 regardless of their similar maximum static contact angles (SCAs) about 150°. A SCA of 163.1° is obtained on the PTFE NP-filled coating surfaces that have a considerably denser structure than SiO2. Thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses reveal that all fabricated surfaces have good thermal stability and tolerate temperatures up to 550 °C. The PTFE NP-filled coating surfaces also exhibit excellent water and acid resistance. A possible mechanism concerning the amount of trapped air is proposed in relation to practical superhydrophobic surface fabrication.
Keywords: Superhydrophobic coating; Hydrophobization; PTFE; SiO2; Nanoparticles; Carbon steel;

Surface quality improvement by Cu activation and oxidation roughening process was studied during electroless coating Cu on boron carbide (B4C) particles. The surface morphology was characterized by scanning electron microscope (SEM) and the phase identification was determined by X-ray diffraction (XRD) analysis. Two aspects concluding surface activation and surface roughening were investigated to understand the effect of each on Cu coating. Cu activation process increased surface activity of B4C by pre-deposition Cu nano-crystals, which was effective and cost-saving when compared with conventional Pd activation method. The influence of activation pH on electroless Cu coating was discussed and a moderate pH 12 is suitable for Cu deposition. Surface roughening process availably promoted wettability of B4C particles with aqueous solution. Etched pits were formed on B4C surface and resulted in fresh surface exposed after oxidization roughening process, which was beneficial for Cu bonding and coating on B4C surface.
Keywords: Surface modification; Boron carbide; Electroless copper coating; Composites;

Facile method to prepare CdS nanostructure based on the CdTe films by Ligang Ma; Yuehui Chen; Zelu Wei; Hongling Cai; Fengming Zhang; Xiaoshan Wu (740-745).
Nanostructured cadmium sulfide (CdS) plays critical roles in electronics and optoelectronics. In this paper, we report a method to fabricate CdS nanostructure directly on CdTe film, via a thermal annealing method in H2S/N2 mixed gas flow at a relatively low temperature (450 °C). The microstructure and optical properties of CdS nanostructure are investigated by X-ray diffraction, transmission electron microscopy, Raman, and photoluminescence. The morphology of CdS nanostructure, evolving from nanowires to nanosheets, can be controlled by the thickness of Au film deposited on the CdTe film. And CdS nanostructures are single crystalline with the hexagonal wurtzite structure. Raman spectroscopy under varying the excitation wavelengths confirm that synthesized CdS-CdTe films contain two layers, i.e., CdS nanostructure (top) and CdTe layer (bottom). The change of morphology modifies its luminescence properties. Obviously, through simply thermal annealing in H2S/N2 mixed gas, fabricating CdS nanostructure on CdTe film can open up the new possibility for obtaining high efficient CdTe solar cell.
Keywords: CdTe film; Thermal annealing; CdS nanostructure; Raman spectroscopy;

The pitting corrosion mechanism of high strength pipeline steel in aerated NaCl solutions with different pH and chloride content was investigated, using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). The pitting behavior in alkaline solutions was found to be significantly different from that in neutral and acidic solutions. Electrochemical results and SEM images indicate that the product film formed on the steel surface results in different corrosion behavior in an alkaline solution. SEM images show that pH and chloride concentration in the bulk solution have a great influence on the pitting morphology. Unique large pit morphology due to corrosion in neutral/acidic solutions with 0.05 mol/L NaCl was observed. The relationship between solution pH and the effect of chloride concentration is also discussed.
Keywords: Pipeline steel; Pitting corrosion; Chloride; Polarization; EIS; SEM;

Characterization of HfO x N y thin film formation by in-situ plasma enhanced atomic layer deposition using NH3 and N2 plasmas by Young Bok Lee; Il-Kwon Oh; Edward Namkyu Cho; Pyung Moon; Hyungjun Kim; Ilgu Yun (757-762).
The structural and electrical characteristics of in-situ nitrogen-incorporated plasma enhanced atomic layer deposition (PE-ALD) HfO x N y thin films using NH3 and N2 plasmas as reactants were comparatively studied. The HfO x N y test structures prepared using NH3 and N2 plasmas were analyzed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and high resolution transmission electron microscopy (HR-TEM) to investigate the chemical composition, crystallinity, and cross-sectional layers including the interfacial layer, respectively. By utilizing NH3 and N2 plasmas, the nitrogen-incorporated HfO x N y thin films fabricated by in-situ PE-ALD showed a high dielectric constant and thermal stability, which suppresses the interfacial layer and increases the crystallization temperature. The high leakage current densities of the HfO x N y thin film test structures fabricated using NH3 and N2 plasmas caused by lowering the energy bandgap and band offset are related to the Hf―N bond ratio and dielectric constant.
Keywords: HfON thin film; Plasma enhanced atomic layer deposition; NH3 plasma; N2 plasma; Interfacial layer;

Effect of wettability and surface roughness on the adhesion properties of collagen on PDMS films treated by capacitively coupled oxygen plasma by J.A. Juárez-Moreno; A. Ávila-Ortega; A.I. Oliva; F. Avilés; J.V. Cauich-Rodríguez (763-773).
Direct chemical bonding of biomolecules to the surface of chemically inert polymers such as polydimethylsiloxane (PDMS) is not easily achieved. Therefore, pre-activation of such materials, followed by attachment of the biomolecule is necessary.This paper describes a procedure to functionalize a PDMS surface by oxygen-based plasma followed by the adhesion of collagen type I for the preparation of adhesive-free bilayer composite intended as skin substitute. Plasma treatments between 40 and 120 W for 5 to 15 min were used and the extent of surface modification was followed by contact angle, Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM) and adhesion test. It was found that as the plasma power and time were increased, PDMS contact angle decreased while surface roughness increased as revealed by SEM and AFM. The formation of oxygen-containing functional groups at the surface was detected by FTIR. T-peel tests, performed on PDMS treated at 80 W/13 min and covered with collagen showed maximum peel strength of 0.1 N/mm which was 3 times higher than that measured for the untreated bilayer composite. The observed enhancement in the adhesion strength was attributed to the increased mechanical interlocking driven by the increased roughness and the formation of hydrophilic functional groups.
Keywords: Oxygen plasma; Surface treatment; PDMS; Collagen; Adhesion;

At millimeter dimensions or less, the conventional bonding technology tends to suffer from severe performance and reliability degradation. Moreover, the high heating temperature is usually needed. Here, we report a room-temperature electrical surface fastener based on copper/polystyrene core/shell nanowire (NW) arrays. Uniquely, this electrical surface fastener exhibits high macroscopic adhesion strength (∼44.42 N/cm2) and low electrical resistance (∼0.75 × 10−2  Ω cm2). Furthermore, it was found that the adhesion strength of this surface fastener can be mediated by the shell thickness and the molecular weight of polystyrene. Finally, the contact mechanics theory was used to explain the adhesion mechanism.
Keywords: Core/shell nanowire; Room-temperature; Electrical bonding; Electronic packaging;

Formation of Ge0 and GeO x nanoclusters in Ge+-implanted SiO2/Si thin-film heterostructures under rapid thermal annealing by A.F. Zatsepin; D.A. Zatsepin; I.S. Zhidkov; E.Z. Kurmaev; H.-J. Fitting; B. Schmidt; A.P. Mikhailovich; K. Lawniczak-Jablonska (780-784).
The results of X-ray photoelectron spectra (XPS valence band and core levels) measurements for Ge+ implanted SiO2/Si heterostructures are presented. These heterostructures have a 30 nm thick Ge+ ion implanted amorphous SiO2 layer on p-type Si. The chemical-state transformation of the host-matrix composition after Ge+ ion implantation and rapid thermal annealing (RTA) are discussed. The XPS-analysis performed allows to conclude the formation of Ge0 and GeO x clusters within the samples under study. It was established, that the annealing time strongly affects the degree of oxidation states of Ge-atoms.
Keywords: Silica; Film; Germanium; Implantation; Nanoclusters; XPS;

We investigate aluminum thin film growth on Ni(1 0 0) substrate by means of molecular dynamics simulation. Embedded Atom Method interaction potential is considered. The simulation is performed at 300 K using an incident energy of 1 eV. The substrate-grown film interface shows the coexistence of hexagonal and fourfold structures in the first layer during the initial stage of deposition. As the deposition proceeds, the hexagonal geometry transforms to fourfold one which becomes dominant toward the end of deposition. The coverage of this layer exceeded 100%. Moreover, the deposited Al atoms with fourfold geometry adopt the lattice parameter of Ni as the thickness of deposited film increases. The interface mismatch investigation revealed that the roughness is dictated by how the Al(1 1 1) fits to the Ni(1 0 0) substrate, which may be reflected by a wavy effect occurring in both lateral directions. Furthermore, the film grows by a layer-by-layer mode with a coverage rate greater than 66.7% in the first three layers, while it follows an island mode with a coverage rate lower than the previous value (66.7%) beyond the third layer. Overall, a detailed analysis of each layer growth has established a relationship between the number of deposited atoms and the coverage rate of each layer.
Keywords: Film growth; First layer; Interface; Mismatch; Morphology; Molecular dynamics;

The WC–12%Co powders with different contents of CeO2 (0.1–2 wt.%) were deposited on ductile iron by electric contact surface strengthening. The coatings with and without CeO2 were examined and tested for microstructural characteristic, phase structure, microhardness and thermal shock resistance. The comparison concluded that the proper addition of CeO2 could refine the microstructure of coatings and increase the microhardness of the coatings. By the small amount addition of cerium oxide (0.5 wt.%), the solid solution strengthening effect and grain boundaries strengthening effect would delay the time of crack formation and propagation in the coatings and enhance the thermal shock performance.
Keywords: Electric contact surface strengthening; Ductile iron; WC–Co coating; CeO2 addition; Thermal shock performance;

Facet-controlled synthesis and facet-dependent photocatalytic properties of SnO2 micropolyhedrons by Gengxia Zhou; Xinglong Wu; Lizhe Liu; Xiaobin Zhu; Xiaoshu Zhu; Yanling Hao; Paul K. Chu (798-804).
The facet-dependent properties of SnO2 are of fundamental and practical importance. In this study, by adjusting the deposition temperature during chemical vapor deposition, octahedral SnO2 with the exposed (1 0 1) facet and two other kinds of SnO2 polyhedrons with (1 0 1) and (1 0 0) facets with different ratios are fabricated controllably based on the vapor–solid growth mechanism. A slight increase in the deposition temperature from 1030 to 1070 °C decreases the surface energy of the reduced (1 0 1) facet with Sn termination, leading to the formation of polyhedrons with different area ratios of (1 0 1) to (1 0 0) facets. By adopting the terephthalic acid fluorescent method, the SnO2 octahedrons are demonstrated to have the strongest photocatalytic activity due to the formation of surface states induced by 5s electrons of bivalent Sn on the (1 0 1) surface. The results reveal that the photocatalytic properties of SnO2 microcrystals can be enhanced by facet-controlled synthesis.
Keywords: SnO2 polyhedron; Surface states; Photocatalytic activity;

Fabrication of ITO-rGO/Ag NPs nanocomposite by two-step chronoamperometry electrodeposition and its characterization as SERS substrate by Rong Wang; Yi Xu; Chunyan Wang; Huazhou Zhao; Renjie Wang; Xin Liao; Li Chen; Gang Chen (805-810).
A novel composite structure of reduced graphene oxide (rGO)–Ag nanoparticles (Ag NPs) nanocomposite, which was integrated on the indium tin oxide (ITO) glass by a facile and rapid two-step chronoamperometry electrodeposition route, was proposed and developed in this paper. SERS-activity of the rGO/Ag NPs nanocomposite was mainly affected by the structure and size of the fabricated rGO/Ag NPs nanocomposite. In the experiments, the operational conditions of electrodeposition process were studied in details. The electrodeposited time was the important controllable factor, which decided the particle size and surface coverage of the deposited Ag NPs on ITO glass. Under the optimized conditions, the detection limit for rhodamine6G (R6G) was as low as 10−11  M and the Raman enhancement factor was as large as 5.9 × 108, which was 24 times higher than that for the ITO–Ag NPs substrate. Apart from this higher enhancement effect, it was also illustrated that extremely good uniformity and reproducibility with low standard deviation could be obtained by the prepared ITO-rGO/Ag NPs nanocomposite for SRES detection.
Keywords: ITO-rGO/Ag NPs; Nanocomposite; chronoamperometry electrodeposition; SERS; Enhance factors;

A new BODIPY/nanoparticle/Ni affinity system for binding of cytochrome c by Esra Maltas; Ahmed Nuri Kursunlu; Gulsin Arslan; Mustafa Ozmen (811-816).
In this study, 3,5-{Bis[4,4-difluoro, 8-(2,6-diethyl, 1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene)]}benzoylchloride (BODIPY) was synthesized for the improving of a new immobilized metal affinity supporting material. Firstly, the synthesized BODIPY was immobilized on iron oxide superparamagnetic nanoparticles (SPIONs) and then, Ni(II) ions were chelated with the active terminals of BODIPY on nanoparticles surfaces to prepare an immobilized metal affinity (IMA) adsorbent for protein adsorption. The amount of BODIPY coated on SPIONs was about 29.7 μM at 10 mg nanoparticles. 738 μmol of Ni(II) ions were loaded to 10 mg of the SPIONs/BODIPY. The binding amount of cytochrome c was found to be 170 μg to the SPIONs/BODIPY/Ni at pH 7.4. The binding amount of the molecules on SPIONs was analyzed by using UV–vis, fluorescence and atomic absorption spectroscopy. The characterization of the prepared surfaces was performed by FT-IR, SEM and TEM.
Keywords: BODIPY; Nanoparticles; Affinity; Protein; Separation;

Statistical optimization of microencapsulation process for coating of magnesium particles with Viton polymer by Seied Mahdi Pourmortazavi; Saeed Babaee; Fatemeh Shamsi Ashtiani (817-825).
The surface of magnesium particles was modified by coating with Viton as an energetic polymer using solvent/non-solvent technique. Taguchi robust method was utilized as a statistical experiment design to evaluate the role of coating process parameters. The coated magnesium particles were characterized by various techniques, i.e., Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and thermogravimetry (TG), and differential scanning calorimetry (DSC). The results showed that the coating of magnesium powder with the Viton leads to a higher resistance of metal against oxidation in the presence of air atmosphere. Meanwhile, tuning of the coating process parameters (i.e., percent of Viton, flow rate of non-solvent addition, and type of solvent) influences on the resistance of the metal particles against thermal oxidation. Coating of magnesium particles yields Viton coated particles with higher thermal stability (632 °C); in comparison with the pure magnesium powder, which commences oxidation in the presence of air atmosphere at a lower temperature of 260 °C.
Keywords: Magnesium powder; Polymer coating; Viton A; Atmospheric corrosion; Coating process parameters;

The thickness of native oxides on aluminum alloys and single crystals by J. Evertsson; F. Bertram; F. Zhang; L. Rullik; L.R. Merte; M. Shipilin; M. Soldemo; S. Ahmadi; N. Vinogradov; F. Carlà; J. Weissenrieder; M. Göthelid; J. Pan; A. Mikkelsen; J.-O. Nilsson; E. Lundgren (826-832).
We present results from measurements of the native oxide film thickness on four different industrial aluminum alloys and three different aluminum single crystals. The thicknesses were determined using X-ray reflectivity, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. In addition, atomic force microscopy was used for micro-structural studies of the oxide surfaces. The reflectivity measurements were performed in ultra-high vacuum, vacuum, ambient, nitrogen and liquid water conditions. The results obtained using X-ray reflectivity and X-ray photoelectron spectroscopy demonstrate good agreement. However, the oxide thicknesses determined from the electrochemical impedance spectroscopy show a larger discrepancy from the above two methods. In the present contribution the reasons for this discrepancy are discussed. We also address the effect of the substrate type and the presence of water on the resultant oxide thickness.
Keywords: Aluminum alloy; Aluminum single crystal; Thin native oxide film thickness; Electrochemical impedance spectroscopy; X-ray reflectivity; X-ray photoelectron spectroscopy;

Surface activation of carbon paper with potassium dichromate lotion and application as a supercapacitor by Zhiyu Cheng; Peng Liu; Bing Guo; Yongfu Qiu; Pingru Xu; Hongbo Fan (833-838).
An effective strategy using potassium dichromate lotion to activate surfaces of commercial carbon papers leading to enhanced electrochemical capacitances was reported.In this paper, an effective strategy using potassium dichromate lotion to activate surfaces of commercial carbon papers leading to enhanced electrochemical capacitances was reported. It is revealed that surfaces of activated carbon papers became rougher and their specific surface areas enlarged after treatment. Further, surface hydrophilicity of the treated carbon papers enhanced due to the generation of hydrophilic groups such as hydroxyl (–OH), carbonyl (〉C=O) and carboxyl (–COOH) and they act as strong polar sites to absorb water molecules. With the synergistic effect of enlarged specific surface area and enhanced surface hydrophilicity, the activated carbon papers provide high areal capacitances. In general, this strategy offers a feasible pathway to make commercial carbon paper a promising candidate for practical supercapacitors and is expected to extend to other carbon based electrode materials.
Keywords: Supercapacitor; Carbon paper; Potassium dichromate lotion; Nanomaterials;

Si rich oxide (SRO) thin films were annealed by two-step rapid thermal annealing (RTA) to form SiO2-matrix silicon-nanocrystals (Si-NCs). The effects of the amount of Si rings in SRO thin films on the phase separation and crystallization processes of annealed thin films were investigated using Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Results showed that the amount of Si rings exerted little effects on the phase separation and the crystallization of SiO0.7 thin films. Moreover, the amount of Si rings significantly influenced the crystallization of SiO1.5 thin films. The crystalline fraction of 1000 °C-SiO1.5 thin films firstly increased from 7% to 15% with increased of the amount of Si rings. The changes in crystallization processes were most possibly due to the different amount of Si―O4 bond in the SRO thin films with different amount of Si rings. Our work indicated that the amount of Si rings could facilitate the crystallization of annealed thin films with higher O/Si atomic ratio.
Keywords: Si nanocrystal; Si rings; Phase separation; Crystallization;

Morphology control of porous CuO by surfactant using combustion method by Chengjun Dong; Xuechun Xiao; Gang Chen; Hongtao Guan; Yude Wang (844-848).
Diverse morphologies of porous CuO were fabricated using surfactant as soft template via a solution combustion method. It is found that a mixture of glycine and ethylene glycol (EG) (1:1) is much more favorable than individual fuel for the fabrication of CuO. All as-synthesized products are surfactant indispensable monoclinic CuO phase. The CuO synthesized without any surfactant is foam network, however, it evolves into basic flake-like morphology with different pores and assembling microstructures in the presence of surfactant. We believe that the different distributions of anions and cations originated from the effect of surfactant lead to the variations of CuO morphology.
Keywords: CuO; Porous materials; Surfactant; Combustion synthesis; Microstructure;

Evaluation of defect density by top-view large scale AFM on metamorphic structures grown by MOVPE by Agnieszka Gocalinska; Marina Manganaro; Valeria Dimastrodonato; Emanuele Pelucchi (849-854).
We demonstrate an atomic force microscopy based method for estimation of defect density by identification of threading dislocations on a non-flat surface resulting from metamorphic growth. The discussed technique can be applied as an everyday evaluation tool for the quality of epitaxial structures and allow for cost reduction, as it lessens the amount of the transmission electron microscopy analysis required at the early stages of projects. Metamorphic structures with low surface defectivities (below 106) were developed successfully with the application of the technique, proving its usefulness in process optimisation.
Keywords: Metalorganic vapor phase epitaxy; Atomic force microscopy; Defects; Arsenates; Semiconducting III–V materials;

Mg doping induced high structural quality of sol–gel ZnO nanocrystals: Application in photocatalysis by Chayma Abed; Chaker Bouzidi; Habib Elhouichet; Bernard Gelloz; Mokhtar Ferid (855-863).
Undoped and Mg doped ZnO nanocrystals (NCs) ZnO:x%Mg (x  = 1, 2, 3, and 5) were synthesized using sol–gel method. The structural and optical properties were investigated by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectivity, and photoluminescence (PL). XRD analysis demonstrates that all prepared samples present pure hexagonal wurtzite structure without any Mg related phases. The NCs size varies from 26.82 nm to 42.96 nm with Mg concentrations; it presents an optimal value for 2% of Mg. The Raman spectra are dominated by the E2high mode. For highly Mg doping (5%), the occurrence of silent B1(low) mode suggested that the Mg ions do substitute at Zn sites in the ZnO lattice The band gap energy was estimated from both Tauc and Urbach methods and found to be 3.39 eV for ZnO:2%Mg. The PL spectra exhibit two emission bands in the UV and visible range. Their evolution with Mg doping reveals the reduction of defect density in ZnO at low Mg doping by filling Zn vacancies.In addition, it was found that further Mg doping, above 2%, improves the photocatalytic activity of ZnO NCs for photodegradation of Rhodamine B (RhB) under sunlight irradiation. The efficient electron–hole separation is the main factor responsible for the enhancement of photocatalytic performance of Mg doped ZnO NCs.Through this work, we show that by varying the Mg contents in ZnO, this material can be a potential candidate for both optoelectronic and photocatalytic applications.
Keywords: ZnO NPs; Sol–gel method; Optical properties; Photocatalysis;

A DFT comparative study of single and double SO2 adsorption on Pt-doped and Au-doped single-walled carbon nanotube by Mehdi Yoosefian; Mansour Zahedi; Adeleh Mola; Samira Naserian (864-869).
Adsorption of single and double SO2 gas molecule(s) on the surface of Pt-doped and Au-doped (5,5) single-walled carbon nanotubes (Pt/CNT-V and Au/CNT-V) were investigated by using density functional theory (DFT) at B3LYP/LANL2DZ level. The results showed the following: firstly, adsorption on Au/CNT-V is independent of special orientation, secondly, SO2 adsorption on Pt/CNT-V in single case is stronger than Au/CNT-V, and finally, adsorption of the first molecule influences adsorption of the second one. Upon adsorption of SO2 molecule(s), the energy gap of Pt/CNT-V were considerably reduced, resulting in enhanced electrical conductivity but in Au/CNT-V, despite of adsorption energy similar to Pt/CNT-V, E g slightly increased. In order to consider the effect of adsorption on electronic properties, DOS and PDOS calculations were performed. Moreover, NBO analysis was done to reach more understanding about intermolecular interactions. In conclusion, chemical reactivity was investigated in terms of chemical hardness, softness and work function (ϕ).
Keywords: SO2 adsorption; DFT; Sensor; NBO; Chemical properties;

The SEM of CF/NiCo2S4/Ni(OH)2 core-shell heterostructured arrays on carbon-fabric and the electrochemical properties of the heterostructured arrays.High-performance supercapacitor electrodes with a core-shell heterostructure of carbon-fabric/NiCo2S4/Ni(OH)2 are rationally designed. The NiCo2S4 nanotube core synthesized by two step hydrothermal methods has a diameter of about 120 nm and a thickness of about 25 nm. The Ni(OH)2 shell prepared by electrochemical deposition method is made up by the small Ni(OH)2 ultrathin sheets. With this design and method, high specific capacitance of 2700 F/g at a current density of 1 mA/cm2 is found from NiCo2S4/Ni(OH)2 heterostructured arrays. These samples show energy density of 120 Wh/kg and power density of 0.4 kW/kg at a current density of 1 mA/cm2, and good cycle stability with 78% capacitance retention after 2000 circles.
Keywords: Pseudocapacitance; Ni(OH)2; NiCo2S4; Nanotube; High electrical conductivity;

Durable superhydrophobic wool fabrics coating with nanoscale Al2O3 layer by atomic layer deposition by Xingfang Xiao; Genyang Cao; Fengxiang Chen; Yunrong Tang; Xin Liu; Weilin Xu (876-879).
To obtain superhydrophobic surface, aluminum oxide was deposited onto wool fabrics using atomic layer deposition (ALD) by exposing them to alternating pulses of trimethylaluminum and water at 80 °C. Scanning electron microscope (SEM) and X-ray fluorescence (XRF) analysis showed that Al2O3 layer and uniform Al2O3 nanoparticle were formed around the surface of ALD coated wool fiber, which showed higher surface roughness than control wool fiber. The static water contact angles of ALD coated wool fabrics increased from 130° to around 160°, and had a higher durability than that of control wool fabric. The dynamic water contact angles of all samples were also tested. Furthermore, the common household liquids also existed as ball-like droplet on the ALD coated wool fabrics and as stain spot on the control wool fabrics after exposure for 1800 s.
Keywords: Atomic layer deposition; Aluminum oxide; Wool fabrics; Superhydrophobic;

Screen-printed masking of transparent conductive oxide layers for copper plating of silicon heterojunction cells by Ankit Khanna; Kurt-Ulrich Ritzau; Mathias Kamp; Aleksander Filipovic; Christian Schmiga; Markus Glatthaar; Armin G. Aberle; Thomas Mueller (880-886).
Replacing expensive silver with inexpensive copper for the metallisation of silicon wafer solar cells can lead to substantial reductions in material costs associated with cell production. Copper metallisation is especially applicable to hydrogenated amorphous/crystalline silicon heterojunction cells since the transparent conductive oxide (TCO) layer in such cells is expected to provide an adequate barrier to prevent cell degrading copper diffusion into silicon. For copper plating on heterojunction cells it is necessary to mask the TCO surface to define the grid electrode. In this paper we investigate screen-printed masking of TCO surfaces to define copper-plated electrodes of heterojunction cells. A masking process is developed and various masking and plating aspects are evaluated. The focus of these investigations is on the characterisation of metal–TCO interfaces and on determining the influence of textured silicon wafer surfaces on the masking process. As a proof of concept, heterojunction cells are fabricated with copper-plated front contacts defined by screen-printed TCO masking. The copper-plated heterojunction cells achieve conversion efficiencies comparable to reference heterojunction cells with evaporated front contacts defined by photolithography.
Keywords: Solar cells; Silicon heterojunction; Copper plating; Masking; Screen printing;

Spray pyrolytic deposition of ruthenium incorporated cobalt oxide thin film electrodes was carried out via methanolic route at 623 ± 2 K. Structural, morphological, optical, compositional and electrochemical study was made using XRD, SAED, SEM, TEM, UV–vis, EDX, XPS and electrochemical work station. Deposited samples shows face centered cubic crystal structure for Co3O4 and tetragonal for RuO2 having crystalline nature was confirmed form SAED. Mixed oxide samples having porous nano-grain morphology and mixed microstructure as observed form SEM and TEM. Cyclic voltammogram study reveals double-pseudo-capacitive nature with optimum specific capacitance (SC) 628.33 F/g at the scan rate 1 mV/s in 1 M KOH with good stability. Charge–discharge behavior was studied to calculate electric parameters such as specific energy (SE), specific power (SP) and columbic efficiency (η). The calculated maximum values are SE 19.94 W h/kg, SP 5.33 kW/kg and η 99.43%. Electrochemical impedance study was made in the frequency range 1  mHz to 1 MHz to see the internal resistance and capacitive behavior of the optimized sample. The randles equivalent circuit and its parameters are reported in the text.
Keywords: Mixed oxides; Spray pyrolysis; TEM; XPS; Supercapacitor-electrode; Impedance;

Hierarchically porous NiAl-LDH nanoparticles as highly efficient adsorbent for p-nitrophenol from water by Yayue Sun; Jiabin Zhou; Weiquan Cai; Rusong Zhao; Jinpeng Yuan (897-903).
Nickel aluminum layered double hydroxides (LDHs) fabricated via sodium citrate (SC) assistant hydrothermal route were evaluated for removing p-nitrophenol from aqueous solutions. The characterization results indicate that the NiAl-LDHs nanoparticles have well-ordered layer structure with highly crystalline nature. The NiAl-LDH possessed hierarchically porous nanoarchitectures with high surface area (108.7 m2/g) and great pore volume (0.41 cm3/g). Meanwhile, interlamellar spacing of NiAl-LDH was increased to 0.73 nm, demonstrating that the citric acid ion was intercalated into NiAl-LDH in vertical alignment. The morphology of NiAl-LDH changed from a series of disordered growth hexagon nanosheets to the flower-like microspheres with modification of variable sodium citrate. The adsorption isotherms of p-nitrophenol on NiAl-LDHs obey the Langmuir equation. It is worthy to note that the NiAl-LDH modified by sodium citrate with the addition of 2.316 g exhibits excellent adsorption performance with the maximum p-nitrophenol adsorption capacity of 77.7 mg/g.
Keywords: NiAl-LDH; p-Nitrophenol; Sodium citrate; Adsorption;

Water contact angles on three types of Si(1 1 1) and (0 0 1) surfaces were measured in nitrogen gas atmosphere without exposing them to air; the surfaces were prepared to be (I) cleaned and reconstructed, subsequently (II) atomic hydrogen (H) terminated, or (III) thinly oxidized in an ultrahigh vacuum (UHV) chamber. The surfaces were characterized by Auger electron spectroscopy and atomic force microscopy. The H-terminated Si surfaces showed as less hydrophilic with a water contact angle of about 37° on the (1 1 1) and about 60° on the (0 0 1) surface, respectively. The clean and oxidized surfaces showed as super-hydrophilic with the angles less than 6°. To quantitatively evaluate the contact angles on the super-hydrophilic surfaces, an optical interference fringe method was used under an optical microscope in air. The most super-hydrophilic surface was the oxidized Si(1 1 1) surface. The reactivity of the Si surfaces and their degree of hydroxyl group termination to the Si surfaces responsible for water wettability were discussed.
Keywords: Silicon; Water contact angle; Super-hydrophilicity; Optical interference fringe method; Atomic hydrogen termination; Oxidation;

Electrolyte effects on the surface chemistry and cellular response of anodized titanium by Naofumi Ohtsu; Taro Kozuka; Mitsuhiro Hirano; Hirofumi Arai (911-915).
Anodic oxidation of titanium (Ti) material is used to enhance biocompatibility, yet the effects of various electrolytes on surface characteristics and cellular behavior have not been completely elucidated. To investigate this topic, oxide layers were produced on Ti substrates by anodizing them in aqueous electrolytes of (NH4)2O·5B2O3, (NH4)2SO4, or (NH4)3PO4, after which their surface characteristics and cellular responses were examined. Overall, no surface differences between the electrolytes were visually observed. X-ray photoelectron spectroscopy (XPS) revealed that the anodized surfaces are composed of titanium dioxide (TiO2), while incorporation from electrolyte was only observed for (NH4)3PO4. Surface adsorption of carbon contaminants during sterilization was suppressed by anodization, leading to lower water contact angles. The attachment of MC3T3-E1 osteoblast-like cells was also improved by anodization, as evidenced by visibly enlarged pseudopods. This improved attachment performance is likely due to TiO2 formation. Overall, electrolyte selection showed no effect on either surface chemistry or cellular response of Ti materials.
Keywords: Anodic oxidation; Titanium; Electrolyte; Surface chemistry; Cellular response;

Preparation and characterization of hydrophilic silicon dioxide film on acrylate polyurethane coatings with self-cleaning ability by Xin Yang; Liqun Zhu; Yichi Chen; Baiqing Bao; Jinlong Xu; Weiwei Zhou (916-923).
A hydrophilic silicon dioxide film which was prepared by silicon dioxide sol could be coated on the acrylate polyurethane coating and translate the wettability of the coating from hydrophobic (CA = 85°) to hydrophilic (CA = 16°). The silicon dioxide sol was prepared by hydrolyzing tetraethoxysilane (TEOS) in aqueous medium and formed a hydrophilic film on acrylate polyurethane surface at 60 °C. The concentration of silicon dioxide sol influenced the film wettability and the hydrophilicity was studied by static contact angle and sliding angle measurements. It was observed that with increase in the ratio of the water/silicon dioxide sol from 0:1 to 3:1, the contact angle decreased from 35° to 16° and the sliding angle decreased obviously. Compared with hydrophobic acrylate polyurethane coating, the hydrophilic silicon dioxide film exhibited better self-cleaning ability which was confirmed by the self-cleaning test through measuring the specular gloss of coatings before contamination and after water droplets spray. Furthermore, there was little dust left on the hydrophilic silicon dioxide film after exposed to an outdoor environment for ca. 50 days.
Keywords: Hydrophilic silicon dioxide film; Acrylate polyurethane coating; Self-cleaning ability; Self-cleaning test;

Multi-technique investigation of Roman decorated plasters from Villa dei Quintili (Rome, Italy) by Vincenza Crupi; Giuliana Galli; Mauro Francesco La Russa; Francesca Longo; Giacomo Maisano; Domenico Majolino; Marco Malagodi; Antonino Pezzino; Michela Ricca; Barbara Rossi; Silvestro Antonio Ruffolo; Valentina Venuti (924-930).
In the present study, we investigated by the joint use of portable instrumentations, namely a handheld X-ray fluorescence (XRF) analyser and a portable Raman spectrometer, the painted surface of plasters withdrawn from different areas of an important Roman monumental complex, known as Villa dei Quintili (Rome, Italy), dated back to the first half of the 2nd century a.C. XRF and Raman measurements contributed to the identification of the pigments through the elemental and molecular composition, respectively. In particular, the multi-technique non-invasive approach proved to be crucial for distinguishing two different reddish pigments. In order to confirm and integrate XRF and Raman results, two micro-destructive laboratory methods, namely optical microscopy (OM) and scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDS), were also employed on the same samples. All the experimental results shed light on the material characterizing the painted surface layer and the painting methodologies, providing in principle useful information for proper restoration processes. It is worth underlining that this experimental investigation takes part of a recent multidisciplinary study performed on this impressive archaeological site, aimed to characterize for the first time the monumental complex from an archaeometric point of view.
Keywords: X-ray fluorescence; Raman scattering; Optical microscopy; SEM-EDS; Roman decorated plasters; Pigments;

Tin oxide thin films doped with different concentrations of ruthenium were deposited on the glass substrates at 450 °C by nebulizer spray pyrolysis technique. The structural, morphological, thickness and optical properties of thin films were investigated by X-ray diffraction, scanning electron microscopy, stylus profilometer and ultra violet spectrometer techniques. X-ray diffraction pattern confirms the tetragonal crystal structure for pure and ruthenium doped tin dioxide thin films. Ruthenium doped tin dioxide thin films are polycrystalline in nature. Scanning electron microscopy shows the modification of surface morphology of tin dioxide films due to varying concentration of ruthenium. Largest spheres, rings and interconnected fibers are present in the scanning electron microscopy images. Energy dispersive analysis reveals the average atomic percentage of pure and ruthenium doped tin dioxide present in the films developed. Stylus profilometer was used to measure the film thickness. Pure, 5, 10 and 15 wt% ruthenium doped tin dioxide thin films are found to have 327, 349, 386 and 425 nm thickness. Optical studies divulge that the band gap energy decreases from 3.55 eV to 3.04 eV due to the increased ruthenium concentrations. Gas sensing properties of pure and ruthenium doped tin dioxide thin films have been studied for various gases.
Keywords: Thin films; Nebulizer spray pyrolysis; Ruthenium; Gas sensing;

Surface modification of chitosan/PEO nanofibers by air dielectric barrier discharge plasma for acetylcholinesterase immobilization by Naghme Dorraki; Nasrin Navab Safa; Mehdi Jahanfar; Hamid Ghomi; Seyed-Omid Ranaei-Siadat (940-947).
There are different methods to modify polymer surfaces for biological applications. In this work we have introduced air-dielectric barrier discharge (DBD) plasma at atmospheric pressure as an economical and safe method for modifying the surface of electrospun chitosan/PEO (90/10) nanofibers for acetylcholinesterase (AChE) immobilization. According to the contact angle measurement results, the nanofibers become highly hydrophilic when they are exposed to the DBD plasma for 6 min in compared to unmodified membrane. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) results reveal hydroxyl, C=O and NH3 + polar groups increment after 6 min plasma treatment. Contact angle measurements and ATR-FTIR results are confirmed by X-ray photoelectron spectroscopy (XPS). AChE at pH 7.4 carries a negative charge and after immobilization on the surface of plasma-treated nanofibrous membrane attracts the NH3 + group and more enzyme activity is detected on the plasma-modified nanofibers for 6 min in compared to unmodified nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used for the surface topography and morphology characterization. The results have proved that air-DBD plasma is a suitable method for chitosan/PEO nanofibrous membrane modification as a biodegradable and functionalized substrate for enzyme immobilization.
Keywords: Chitosan; Nanofiber; Plasma modification; DBD; AChE; Enzyme immobilization;

Structural, electronic and energetic properties of FeCl3 and CrO3 interacting with (10,0) BN nanotube were obtained using ab initio calculation based on the density functional theory. It was found that the FeCl3 and CrO3 molecules behave as an electron acceptor in the presence of the BNNT in all the configurations studied. In a more stable configuration, the binding energy is much stronger, suggesting that the interaction is through a chemisorption regime.
Keywords: Boron nitride; Electronic properties; DFT;

Changes in wetting and contact charge transfer by femtosecond laser-ablation of polyimide by X.D. Guo; Y. Dai; M. Gong; Y.G. Qu; L.E. Helseth (952-956).
In this study it is demonstrated that the triboelectric charging of polyimide thin films is significantly reduced by using a femtosecond laser to nanostructure its. It is found that the contact charge transfer between laser-ablated Kapton and aluminum is almost negligible, and even much lower than the significant current occurring when non-treated Kapton touches the metal. Scanning electron microscopy demonstrates that laser ablation produces a hierarchical micro and nanostructure, and it is found that the structural anisotropy leads to spatially varying contact angles of water droplets residing on the surface. Raman spectra suggest that the centers of the laser-ablated tracks are carbonized; therefore, the loss of insulation can be responsible for the reduction of charge transfer.
Keywords: Polyimide; Contact electrification; Wetting; Raman spectroscopy;

BiOCl nanosheets with tunable lamella thickness and dominantly exposed {0 0 1} facets were selectively synthesized via a facile hydrothermal method. By modifying the synthetic parameters, such as the amount of P123 and mannitol, the reaction time, types of surfactants, the size, thickness, morphologies, and percentage of {0 0 1} facets over BiOCl nanosheets were well controlled. The exposed {0 0 1} facets with high surface energy and high density of oxygen atoms are not only conducive to the adsorption of the rhodamine B (RhB) dye but also can accumulate the photo-generated electrons, which can be captured by O2 and converted into reactive oxygen species O2 •. Therefore, the resultant ultrathin BiOCl nanosheets with exposed {0 0 1} facets exhibit superior catalytic activity for dye photosensitization degradation under visible light irradiation. Impressively, the ultrathin BiOCl nanosheets prepared with P123 and mannitol manifest superior catalytic activity and RhB was completely degraded within 20 min. Our current work is expected to offer a new insight into photocatalytic theory for better understanding of visible light photocatalytic reactions and rational design of highly active photocatalysts.
Keywords: Morphology; Photocatalytic; Nanosheets; Facets; Surface;

Electronic and surface properties of Ga-doped In2O3 ceramics by A. Regoutz; R.G. Egdell; D.J. Morgan; R.G. Palgrave; H. Téllez; S.J. Skinner; D.J. Payne; G.W. Watson; D.O. Scanlon (970-982).
The limit of solubility of Ga2O3 in the cubic bixbyite In2O3 phase was established by X-ray diffraction and Raman spectroscopy to correspond to replacement of around 6% of In cations by Ga for samples prepared at 1250 °C. Density functional theory calculations suggest that Ga substitution should lead to widening of the bulk bandgap, as expected from the much larger gap of Ga2O3 as compared to In2O3. However both diffuse reflectance spectroscopy and valence band X-ray photoemission reveal an apparent narrowing of the gap with Ga doping. It is tentatively concluded that this anomaly arises from introduction of Ga+ surface lone pair states at the top of the valence band and structure at the top of the valence band in Ga-segregated samples is assigned to these lone pair states. In addition photoemission reveals a broadening of the valence band edge. Core X-ray photoemission spectra and low energy ion scattering spectroscopy both reveal pronounced segregation of Ga to the ceramic surface, which may be linked to both relief of strain in the bulk and the preferential occupation of surface sites by lone pair cations. Surprisingly Ga segregation is not accompanied by the development of chemically shifted structure in Ga 2p core XPS associated with Ga+. However experiments on ion bombarded Ga2O3, where a shoulder at the top edge of the valence band spectra provide a clear signature of Ga+ at the surface, show that the chemical shift between Ga+ and Ga3+ is too small to be resolved in Ga 2p core level spectra. Thus the failure to observe chemically shifted structure associated with Ga+ is not inconsistent with the proposal that band gap narrowing is associated with lone pair states at surfaces and interfaces.
Keywords: Transparent conducting oxide; Band bending; Dopant solubility; Ceramic;

Effect of Ag addition on the magnetic and electrical properties of La0.67Ca0.33MnO3 films by Xuepeng Yin; Xiang Liu; Yanhong Zhan; Hui Zhang; Qingming Chen (983-987).
La0.67Ca0.33MnO3:mol%Ag x (LCMO:Ag x , x  = 0, 0.04, 0.08, 0.10 and 0.20) films were prepared on the single crystalline (1 0 0)-orientated (LaAlO3)0.3–(SrAlTaO6)0.7 (LSAT) substrates by the pulsed laser deposition (PLD) method. With the increasing of Ag addition, the magnetoresistance (MR) of the LCMO:Ag x films exhibits a significant decrease and the x  = 0 sample reach to the maximum value of MR ratio at 46.6% under 1 T magnetic field, in addition, the metal–insulator transition temperature (T p) improve 20–26 K or 12–18 K for the films at a zero or 1 T fields, respectively. The results maybe due to the fact that Ag enter the host lattice, partially substitute for La3+/Ca2+ ion, and then increase the Mn4+/Mn3+ ratio, which lead to enhance the electrical properties in LCMO:Ag x films.
Keywords: La0.67Ca0.33MnO3:Ag x ; Magnetoresistance; Metal–insulator transition temperature; Pulsed laser deposition;

Adsorption and heterogeneous degradation of rhodamine B on the surface of magnetic bentonite material by Dong Wan; Wenbing Li; Guanghua Wang; Kun Chen; Lulu Lu; Qin Hu (988-996).
A kind of imitation enzyme catalyst, Fe3O4 nanoparticles decorated Al pillared bentonite (Fe3O4/Al-B), was successfully prepared by in situ precipitation oxidization method and then applied for the adsorption and degradation of rhodamine B (RhB) in the presence of H2O2. The catalyst was characterized by XRD, SEM, XPS, BET, VSM and FTIR spectroscopy. The effects of oxidant concentration, initial RhB concentration and iron leaching on the degradation of RhB were investigated. The surface interactions with RhB in the absence and the presence of oxidant could be well described by Langmuir and Langmuir–Hinshelwood models, respectively. The Fe3O4/Al-B showed higher ability of adsorption and degradation efficiency toward RhB than bare Fe3O4 in the batch experiments. The whole degradation process of RhB followed pseudo-first-order rate law and was mainly controlled by surface mechanism reaction. The enhanced degradation efficiency of Fe3O4/Al-B might relate to the enrichment of RhB molecules by Al-B in the vicinities of active sites. Furthermore, the catalyst showed stable catalytic activity and convenient recycling. Negligible iron leaching showed the reused Fe3O4/Al-B can withstood the oxidation.
Keywords: Adsorption; Magnetic bentonite; Heterogeneous catalyst; Rhodamine B;