Current Nanoscience (v.7, #3)

Graphical Abstracts by Bentham Science Publishers (i-viii).
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Are Carbon Nanotubes a Naturally Occurring Material? Hints from Methane CVD Using Lava as a Catalyst by James Mracek, Randall D. Fagan, Rudolf M. Stengelin, Thorsten Hesjedal (294-296).
Single-walled carbon nanotubes (SWNTs) were grown using methane CVD with lava as a catalyst and substrate. Metal-oxidephases embedded in the lava are reduced in the presence of hydrogen, thereby promoting catalytic growth. Scanning electron microscopyand energy-dispersive X-ray spectroscopy show a correlation between the growth of carbonaceous nanomaterials and the presence of ironin the alumina matrix. Raman spectroscopy of the carbon deposits proves the occurrence of SWNTs. Although this growth route lacks efficiency,it provides evidence for the claim that SWNTs are a natural allotrope of carbon and that volcanoes may provide an environmentfor their synthesis.

Carbon Nanotubes as an Advanced Drug and Gene Delivery Nanosystem by Jafar Ezzati Nazhad Dolatabadi, Yadollah Omidi, Dusan Losic (297-314).
New nanomaterials have been extensively explored in recent years for drug delivery applications to address problems associatedwith the conventional drug therapies such as limited drug solubility, poor biodistribution, lack of selectivity and unfavourable pharmacokinetics.Among them, carbon nanotubes (CNTs) have attracted great attention due to their unique physicochemical architecture andproperties. This comprehensive review summarizes the recent advances regarding the use of CNTs for drug delivery. This review includesgeneral information about CNT structures and properties, methods for their dispersion in aqueous solution and basic concepts forCNTs functionalization relevant for their applications in biological systems and delivery of therapeutics. Some toxicological and biocompatibilityissues related to the use of CNTs as pharmaceutical excipients are discussed. Last, recent progress on development of CNTdrug delivery systems with a specific emphasis on gene delivery was reviewed.

Cobalt Catalyzed Carbon Nanotube Growth on Graphitic Paper Supports by V. Engels, J. Geng, G.M. Jones, J.A. Elliott, A.E.H. Wheatley, S.R. Boss (315-322).
The catalytic growth of multi-wall carbon nanotubes on carbon paper is reported. The study employed three cobalt carbonylclusters as catalyst precursors. These were deposited on graphitic paper prior to chemical vapour deposition (CVD) of methane or ethylene.The clusters show differentiated growth behaviour in accordance with precursor size, and with Co2(CO)8 displaying additional activityin the growth of helical nanotube structures. We therefore report an approach for the decoration of graphitic papers with carbon nanotubeswith a view to the production of high area supports.

Synthesis, Characterization and Biodegradation of Novel Poly(L-lactide)/Multiwalled Carbon Nanotube Porous Scaffolds for Tissue Engineering Applications by Hassan Adeli, Sharif Hussein Sharif Zein, Soon Huat Tan, Hazizan Md Akil, Abdul Latif Ahmad (323-332).
This paper reports on the synthesis and characterization of novel poly(L-lactide)/multi-walled carbon nanotube(PLLA/MWCNT) porous scaffolds prepared by the freeze-extraction method. The obtained scaffolds showed well-distributed and interconnectedporous structures with more than 80% porosity and median pore size around 40 m distributed within a region between 50 and150 m in size. As a result of high interfacial interaction between PLLA and the MWCNTs, the scaffolds exhibited remarkable improvementsin mechanical properties such as strength, modulus and elongation. Thermogravimetric analysis (TGA) and differential scanningcalorimetry (DSC) showed enhanced thermal stability and compatibility for PLLA/MWCNT scaffolds. The structural properties ofthe scaffolds were investigated by Fourier-transform infrared spectroscopy (FTIR). In vitro degradation studies of the scaffolds were assessedby immersing the scaffolds in phosphate buffered saline (PBS) for up to 24 weeks. It was found that the incorporation ofMWCNTs in PLLA scaffolds decreased the rate of in vitro degradation.

Carbon nanotubes are synthesized by Low Pressure Chemical Vapor Deposition (LPCVD) system using NH3: C2H2:H2 gasmixtures on iron coated silicon substrate. The iron catalyst was coated on silicon using RF-sputtering method. The growth temperaturewas kept at 600 °C and growth time was 10 mins. The carbon nanotubes are found to have diameters ranging from 50 to 80 nm and lengthof up to a few tens of microns. Raman spectra indicate that the CNTs are highly graphitized and several peaks are also found at low frequencyrange from 100 cm-1 to 500 cm-1 , which are assigned to the radial breathing mode (RBM) which is the characteristic of singlewall carbon nanotubes. Therefore, this sample also contains single walled carbon nanotubes also. The carbon nanotubes showed a turn-onfield of 2.63 V/µm and the maximum current density of 2 mA/cm2. The field enhancement factor was calculated to be 3.941 X 103 for asgrown carbon nanotubes. The carbon nanotubes grown at this lower temperature show good field emission and are suitable for device applications.

PC12 Interaction with Magnetic Nanotubes: Effects on Viability, Cell Differentiation and Cell Translocation Induced by a Magnetic Field by Orazio Vittorio, Vittoria Raffa, Cristina Riggio, Andrea Pietrabissa, Alfred Cuschieri (337-344).
In this paper we used Multi Wall Carbon Nanotubes (MWCNTs) containing 3% of residuals and impurities of Fe, Al, and Zn.MWCNTs, by virtue of Fe at their tips, are able to respond to the effects of external magnetic fields. We demonstrated that MWCNTs interactwith PC12 cells without compromising their viability and differentiation with outgrowth of neurites. We also document that whenexposed to a magnetic field, both undifferentiated and differentiated PC12 cells cultured in CNT-containing medium solution are able tomove towards the magnetic source.

Tricyclic antidepressants (TCAs) have potent local pain blockade properties that could be of interest in relieving chronic painstates as neuropathic pain. The aim of this work was to reach a persistent control of nociceptive and neuropathic pain by means of an injectablecontrolled release system using lower than usual doses of TCAs. To address this issue, amitriptyline, doxepin and imipraminewere encapsulated with poly (lactic-co-glycolic) acid (PLGA) as polymer. Nanoparticles were characterized. The in vitro drug releaseprofile and mechanism was evaluated, and the in vivo analgesic and anti-allodynic activity in front of heat-induced nociceptive pain andsciatic nerve chronic constriction injury, respectively, was tested. The mean±SD particle size and drug loadings (%) of the nanoparticlesobtained were 420±13, 480±73 and 373±25nm, and 40.46±4.11, 31.09±3.02 and 32.20±3.20 % for amitriptyline, doxepin and imipramine,respectively. According to the Korsmeyer-Peppas model, the release mechanism of doxepin was diffusion controlled, while acombination of Fickian diffusion and polymer relaxation/erosion of the PLGA matrix was involved for amitriptyline and imipramine. Afterlocal infiltration of nanoparticles in rats, the antinociceptive and anti-allodynic activity of the encapsulated drugs were long-lastingand higher than that observed from the solutions. Amitriptyline elicited the lower analgesic effect. Doxepin showed the most outstandingresults and its encapsulation led to a 62% and 229% increase in antinociceptive and anti-allodynic activity, respectively. So, this drugcould be considered as a therapeutical alternative in pain relieving treatments.

This paper reports the fabrication of multi-functionalized gold nanoparticles (MFAuNPs) and the application to electrochemicaldetection of nitrite. While gold nanoparticles are modified with thiolated oligonucleotides as usual, they are also immobilized with 5-[1, 2]dithiolan-3-yl-pentanoic acid [2-(naphthalene-1-ylamino)-ethyl]amide (DPAN). Therefore, the oligonucleotides molecules can enhancethe solubility of the MFAuNPs and absorb hexaammineruthenium(III) chloride ([Ru(NH3)6]3+) as electrochemical species on theone hand, with the help of nitrite ions, DPAN immobilized on MFAuNPs will react with 4-(2-aminoethyl)benzenamine which has beenpreviously modified on the surface of a gold electrode on the other hand, thus an electrochemical method for nitrite detection is also proposed.Although the maximum contaminant level (MCL) defined by the Environmental Protection Agency (EPA) for nitrite in drinkingwater is as low as 1 ppm (21.7 M), which is difficult to make detections by the current techniques, the proposed method in this work cangive very satisfactory results.

Colorimetric and Electrochemical Study on the Interaction Between Gold Nanoparticles and Unmodified DNA by Yao Wu, Lianke Liu, Zhiqiang Liang, Zhongming Shen, Xiaoli Zhu (359-365).
Gold nanoparticles have been widely adopted to fabricate DNA sensors and aptasensors. Nevertheless, detailed informationdeep into the mechanism of the interaction between gold nanoparticles and DNA is still under investigation. In this work, we have employedcolorimetric and electrochemical methods to study the interaction between unmodified DNA and colloidal as well as surfaceconfinedgold nanoparticles. It is observed that in both cases, only single-stranded DNA may interact with the nanoparticles; however, theinteraction processes are quite different. Single-stranded DNA binds to colloidal gold nanoparticles rapidly and weakly, while the bindingis much longer and stronger in the case of surface-confined gold nanoparticles. We have discussed the differences and further proposedpossible mechanisms. The results we present in this paper might be helpful for the deep understanding of the interaction between nanomaterialsand DNA, and benefit the design of AuNPs-based DNA sensors and aptasensors.

Interaction Mechanism between Fe3O4 Nanoparticles and Sodium 2-dodecylbenzenesulfonate by Sheng Cui, Benlan Lin, Maohong Fan, Xiaodong Shen (366-370).
In the paper, the dispersion stability of Fe3O4 nanoparticles in water by ball milling with surfactant sodium 2-dodecylbenzenesulfonate (SDBS) was studied. The ball milling time as influence factor on the stability of magnetic fluid was investigated.Then, the nano-Fe3O4 magnetic fluid was prepared and characterized by high-resolution transmission electron microscopy(HRTEM), X-ray diffraction (XRD), particle size analyzer, Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy(XPS). The results show that the best time of ball milling is about 5h. The stably dispersed Fe3O4 mean size is about 34.1 nm. SDBS isadsorbed on the surface of nanoparticles by chemical bonds. SDBS covers Fe3O4 nanoparticles through sulfonate group links. Then anotherSDBS continues to adsorb by physical forces to disperse stably in the water solution by the steric hindrance and electrostatic effect.

Biocompatibility Studies of Functionalized CoFe2O4 Magnetic Nanoparticles by Pranav Kumar Prabhakar, Swetha Vijayaraghavan, John Philip, Mukesh Doble (371-376).
CoFe2O4 nanoparticles of different sizes were synthesised by controlling the digestion time using precipitation method andwere characterised by X-ray diffraction, transmission electron microscopy, dynamic light scattering, and vibrating sample magnetometer.The average crystalline size increases from 13.9 to 19 nm as the digestion time is increased from 1.3 to 120 minutes. The CoFe2O4nanoparticles were coated with two biological polymers, namely polyvinyl alcohol (PVA) and polyethylene glycol (PEG) at various ratiosto enhance their biocompatibility. Coated nanoparticles were analysed for their cytotoxicity by MTT assay against 3T3-L1 adipocytes.Coated nanoparticles were found to be less cytotoxic when compared to uncoated one. The cell viability decreased as the concentrationof the polymer (either PVA or PEG) coating increased. Cell viability decreases as the concentration of nanoparticle increases. At 5μg/ml the cell viability with PEG coated nanoparticles (1:4) was 92.5%, with PVA coated nanoparticles (1:4) was 82.7% and with uncoatednanoparticles it was 46.4%. As the ratio of biopolymers (PVA and PEG) to nanoparticle increases, the viability of the cell increases.The difference between the effect of these two polymers increases as the concentration of the nanoparticle decreases. The antiinflammatoryproperties of these nanoparticles were determined by RTPCR by measuring the two pro-inflammatory cytokines (namelytumor necrosis factor α and IL6). TNF-α and IL6 were upregulated by 3.57- & 2.86 folds their base level with uncoated nanoparticles.Whereas it was upregulated by 1.54- & 1.68-folds with PEG coated and 1.9- & 2.18-folds with PVA coated nanoparticles. Thus thecoated nanoparticles can be used for further biological experiments including magnetic resonance imaging, and in targeted drug deliverysystems for various diseases.

Dielectric Wall Controlled Resonance Light Scattering of Coated Long Gold Nanowire by Jian Zhu, Shu-min Zhao, Jun-Wu Zhao, Jian-Jun Li (377-380).
In this paper, we investigate the effects of a coated dielectric wall on the resonance light scattering (RLS) properties of a longgold nanowire. The RLS is shown to be strongly influenced by the presence of the dielectric surrounding which induces the changes ofthe surface plasmon resonance (SPR) and local polarized field characters. For gold nanowire coated by a dielectric wall, the RLS peakred shifts nonlinearly when the wall thickness is increased, which is different from the linear shift fashion of a bare gold nanowire embeddingin immense dielectric surrounding. Furthermore, the scattering distribution patterns in the transversal section are also dependenton the coated dielectric wall. When dielectric constant of outer surrounding is greater than that of the dielectric wall, the intense scatteringtakes place at the poles of the wall along the incident polarization. On the contrary, greater wall dielectric constant may bring oppositescattering distribution. This tunable light scattering in dielectric wall coated gold nanowire makes it potentially useful in optical biosensingbased on metallic nanoparticle enhanced RLS.

A Non-Alkoxide Sol-Gel Method for the Preparation of Magnetite (Fe3O4) Nanoparticles by Hongzhang Qi, Biao Yan, Wei Lu, Chengkui Li, Yinhui Yang (381-388).
Magnetite (Fe3O4) nanoparticles in the interval of 9~12nm have been synthesized by an non-alkoxide sol-gel method. Throughthis simple technique, sol-gel materials were prepared from ethanolic solutions of metal chlorides without the need for alkoxides, polymericgel agents, or elaborate reaction schemes. The gel formation has been studied, and the research shows that gel formation appears tobe driven primarily by the formation of an Fe(III)-based network which incorporates Fe(II) into its nanoscale solid domains. The researchof the annealing process indicates that magnetite (Fe3O4) nanoparticles can be obtained by annealing only under vacuum, but not in air.Future, Fe3O4 can be oxidized to Fe2O3, as evidenced by XRD, and VSM. The phase structures, morphologies, and particle sizes of Fe3O4nanoparticles were characterized by thermogravimetric-differential thermal analysis (TG-DTA), X-ray Diffraction (XRD) and TransmissionElectron Microscopy (TEM). The results indicate that magnetite (Fe3O4) nanoparticles are homogeneous and have near-sphericalshape with a narrow distribution in particle size. Finally, an investigation of the possible mechanism of Fe3O4 nanoparticles formationwas performed. Both TG-DTA and X-ray Diffraction (XRD) studies suggest that the reaction of the decomposition of the precursor undervacuum conditions leads to Fe3O4 nanoparticles, while the precursors in air atmosphere is directly oxidized to gamma iron oxide. In addition,this approach may suggest a general route to produce complex multicomponent metal oxide in which the nanoscale oxide is stabilizedand spatially distributed.

Therapeutic Nanoparticles and Associated Toxicity by Avnesh Kumari, Vineet Kumar, Sudesh Kumar Yadav (389-395).
Nanoparticles (NPs) are currently widely used for different applications like cosmetics, personal care products and drug deliveryagents. The enormous use and production of NPs resulted in release of NPs into the environment. These NPs find their way intoaquatic, terrestrial and atmospheric environments. These NPs interact with their immediate environments and cause adverse affects onthem. The rapidly growing field of nanotechnology will result in new routes of exposure through inhalation, ingestion, and injection.They can have damaging effects on cellular organells like mitochondria and macromoleculs like DNA. In view of this, there is a need tobetter understand the interactions between the NPs, environment and the organisms. In this article, we have reviewed the well known cytotoxicityassays and toxicity associated with therapeutic NPs.

Optimization of Electrospinning Parameters for Chitosan Nanofibres by Valencia Jacobs, Asis Patanaik, Rajesh D. Anandjiwala, Malik Maaza (396-401).
Electrospinning of chitosan, a naturally occurring polysaccharide biopolymer, has been investigated. In this paper, we reportthe optimization of electrospinning process and solution parameters using factorial design approach to obtain uniform chitosan nanofibres.The parameters studied were electric field strength, ratio of solvents - trifluoroacetic acid (TFA)/ dichloromethane (DCM), concentrationof chitosan in the spinning solution, their individual and interaction effects on the diameter of nanofibres. The selected parameterswere varied at three levels (-1, 0 and +1) using Box and Behnken factorial design. The interaction effect between electric field strength(FS) and concentration of chitosan (CC) as well as that between the ratio of solvents - TFA/DCM (SC) and electric field strength playedthe most significant role, followed by the concentration of chitosan and lastly by the electric field strength in obtaining uniform nanofibres.

Single-Source Route to Bi2S3 Nanorods and their Electrochemical Sensing Properties by L.Z. Pei, J.F. Wang, Y.P. Dong, X.X. Tao, S.B. Wang, C.G. Fan, J.L. Hu, Qian-Feng Zhang (402-406).
A simple and environmentally benign process for the synthesis of Bi2S3 nanorods and their electrochemical sensing propertiesare desirable to be developed in electrochemical sensor application. Orthorhombic Bi2S3 nanorods have been synthesized via a singlesourceapproach using bismuth diethyldithiocarbamate as the precursor under hydrothermal conditions. The products were characterizedby powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, IR, UV-vis spectra and electrochemicalsensing analysis. The decomposition of the complex bismuth diethyldithiocarbamate produces Bi2S3 nanorods with the average diameterof about 80 nm and length of less than 5 m. The electrochemical responses of Bi2S3 nanorod modified glassy carbon electrode to cysteineand ascorbic acid are greatly enhanced suggesting that hydrogen ions participate in the electrochemical oxidation process. The electrochemicalresults demonstrated that the Bi2S3 nanorods are expected to have great potential as the electrochemical sensing cell for detectingcysteine and ascorbic acid.

Preparation and Characterization of 3D Flower-like La2O3 Nanostructures by Shengliang Zhong, Bin Deng, Anwu Xu, Shangping Wang (407-414).
In this work, a facile route using a simple solvothermal reaction and sequential heat treatment process to prepare 3D La2O3flower-like nanostructures without employing templates or matrices for self-assembly is presented. The as-synthesized products werecharacterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), highresolutionTEM (HRTEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TG), differential thermal analysis(DTA), and Fourier transformation IR (FTIR). SEM results demonstrate that the as-prepared flower-like precursor with average size of 5-7 m in diameter is composed of numerous nanoplates with a thickness of about 100 nm. Influencing factors such as solvothermal reactiontemperature, surfactants, reaction time, and solvents were systematically investigated. 3D flower-like La2O3 nanostructures withmany holes on the petals were obtained after calcinations of the flower-like precursor at 800 oC for 4 h. The BET surface area of theflower-like La2O3 nanostructures is 9.98 m2/g. Eu3+ doped flower-like La2O3 nanostructures were also prepared employing the samepreparation process. The flower-like La2O3:Eu3+ nanostructures show a strong red emission corresponding to 5D0 -7F2 transition (625 nm)of Eu3+ under ultraviolet excitation (267 nm). The possible formation mechanism for the 3D flower-like precursor was briefly discussed.

Nanofiber yarns are introduced in this work, formed by PAN nanofibers electrospun from the dimethylformamide (DMF) solutionvia a novel process we recently developed. The fiber properties comparison at selected electrospinning parameters and differentpolymer concentrations are made in order to determine the influences of such parameters on the morphology and the cross-sectionalshape of the nanofibers. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM), along with image processingtechnique are then conducted to investigate the profiles of these PAN nanofibers, in challenging the common conception of a circularcross-section for such fibers. Our results suggest that is nanofibers are in general with irregularity along the fiber longitudinal axis, it isoverly simplistic to use diameter alone in describing the nanofiber thickness. So the cross-sectional shape and area are more desirable.

To date, the activation induced reorganization in membrane nanostructures and alteration in membrane adhesion property ofCD4+ T lymphocytes largely remain unclear yet even though their immunological functions have been well elucidated. The present workfocused on detecting the differences in topography, membrane nanostructures and adhesion/friction behaviors of CD4+ T cells in the absenceand presence of stimulus (Phorbol dibutyrate, PDB, plus Ionomycin, ION). The results showed that, due to cell activation in vitro,(a) the formation of pseudopodia, lamellipodia; (b) the appearance of membrane pores with 200~450 nm in diameter and 70~110 nm indepth; (c) the formation of nanostructural domains with different adhesion behavior; (d) the loading rate and loading force could affectthe measured adhesion force nonlinearly; (e) the dynamic changes in membrane adhesion force, from 348±9.08 pN for resting cells,827.07±24.61 pN for 24 hours of activation, 372.87±9.26 pN for 48 hours of activation, to 302.45±11.42 pN for 72 hours of activation.This work achieved the biophysical changes of CD4+ T cells with and without stimulation, which would enable us to seek new implicationsand potential links between cytoarchitectures, membrane adhesion and immunological functions at the single-cell and nanoscalelevel.

The aim of the present study is to investigate the vitamin B12 conjugated doxorubicin loaded sterically stabilized liposomesfor tumor targeting. Plain and sterically stabilized liposomes were prepared by modified ethanol injection method followed by remoteloading of doxorubicin by ammonium sulphate gradient method. The sterically stabilized liposomes were coupled with vitamin B12 usingpost insertion technique. The average size of liposomes was found to be in range 105-128 nm and maximum entrapment efficiency wasfound to be 89.3-94.5 %. In vitro cell binding of SL-VB12 exhibits 6.28 folds higher binding to B16F10 melanoma cells in comparison tosterically stabilized liposomes. In vitro cytotoxicity study was conducted on B16F10 melanoma cells. SL-VB12 demonstrated strongestcytotoxicity to the tumor cells as compared to non targeted formulations i.e. PL and SL confirming that SL-VB12 was effectively takenup by tumor cells. The pharmacokinetic, tissue distribution and tumor growth inhibition studies were carried out followed by intravenousadministration of liposomal formulations in C57BL/6 mice carrying B16F10 melanoma tumor. The half-life of SL-VB12 and SL wasabout 7.2 and 8.5 fold higher than that of free DOX, respectively. Accumulation of SL-VB12 in the tumor tissue was 18.9 and 2 timeshigher as compared to free DOX and SL respectively after 8 hours. SL-VB12 at the dose of 5 mg DOX/kg resulted in effective retardationof tumor growth. The liposomal formulation also prolong the survival time of mice as compared to free drug. Results indicate that vitaminB12 coupled liposomes bearing doxorubicin are significantly active against primary tumor than non targeted liposomes. In summary,our study indicated that the vitamin B12 coupled sterically stabilized liposomes (SL-VB12) could be used as a targeted carriers tofacilitate the delivery of the encapsulated anticancer drugs into tumor cells by receptor mediated way.

Liposomes: A Review of Manufacturing Techniques and Targeting Strategies by B. Maherani, E. Arab-Tehrany, M. R. Mozafari, C. Gaiani, M. Linder (436-452).
Today, liposomes are among the most applied technologies for the encapsulation and delivery of bioactive agents and manydifferent compounds in biological, pharmaceutical, medical and nutritional research. In this review, classification of liposomal vesicles,methods of their preparation and encapsulation, as well as their applications in food, cosmetics and pharmaceutical industries are reviewed.In addition, the main analytical approaches used to study liposome characteristics such as size, transition temperature, surfacecharge, fluidity, lamellarity, stability and encapsulation efficiency are presented. In the final part of the article, mechanisms of liposometargeting are discussed.

Stimuli-responsive (pH, temperature and magnetic field) 4-vinylpyridine (4-VP)-based nanoparticles in copolymeric formulationwith core-shell morphology were synthesized using N-isopropylacrylamide (NIPAM), 2-hydroxyethyl methacrylate (HEMA),acrylic acid (AAc), and methacrylic acid (MAc) as shell-forming monomers. Keeping the 4-VP ratio constant and varying the comonomeramounts produced particles with variant shell thickness. Multi-responsive p(4-VP)-based nanoparticles were further modified by reactingwith different functional groups containing bromoalkanes by quaternization. These p(4-VP)-based particles were also utilized toinclude composite materials by encapsulating separately prepared magnetic ferrites. To demonstrate the potential usage of the synthesizedparticles and their modified forms as drug delivery devices, naproxene sodium salt as an antibacterial drug was used for in vitro releasestudies in PBS.

In this short review paper, surface energy and site dependent cohesive energy of several Ag clusters are investigated via brokenbonds theory and density functional theory simulation. The theoretical and simulation results shows that surface energy of Ag clusterss(N) are almost equal to the Ag bulk value s(), which shows no size dependence. Considering specific sites, cohesive energy ofsurface atoms Ecsx(N) are related to their coordinated numbers Zsx(N). While cohesive energy of interior atoms Ecix(N) are influenced bythe high pressure existing in clusters.

Nanoliter-Droplet Breakup in Confined T-Shaped Junctions by Yuxiang Zhang, Liqiu Wang (471-479).
Nanoliter-droplet breakup in either symmetrically or asymmetrically confined T-shaped junctions is experimentally studied.The critical condition with which nanoliter droplets will break equally is theoretically analyzed based on the pressure-driven mechanism.The scaling analysis is experimentally confirmed, implying that the droplet breakup in a confined T-shaped junction is a pressure-drivenprocess when the capillary number is less than ~0.1. A semi-empirical correlation is obtained for predicting the equal breakup in symmetricT-shaped junctions. The critical condition is found to be dependent on the initial droplet length, channel depth and capillary number.Besides the equal breakup of nanoliter droplets, a new droplet breakup pattern, unequal breakup, is observed in the symmetric T-shapedjunction. In asymmetric T-shaped junctions the nanoliter-droplet breakup is found to be very difficult.

We synthesize multifunctional nanofluids by incorporating fluorescent dyes into magnetite nanoparticles. The synthesis is carriedout in two different routes, in which nanoparticles with two sizes are coated by two different kinds of stabilizers. The structures ofcoating layers of the as-synthesized nanoparticles are characterized by the analysis of Fourier transform infrared spectra. Magneticinteraction-induced aggregation still exits and is traced by the DLS. Thermal conductivities of the synthesized nanofluids are measuredunder day-light, in the dark and under the UV irradiation. The fluid thermal conductivity varies in a wave-like shape as a function of particleconcentration due to the existence of aggregation. Furthermore, the measured thermal conductivity under UV light is higher thanthose with the other conditions. The collapse of aggregates under UV irradiation due to the unidirectional non-radiative energy transferincreases the number of single magnetite particles and is thus assumed to be responsible for the increase of fluid thermal conductivity.

The effects of evaporative drying and annealing processes on the wettability and morphology characteristics of vapordepositedself-assembled 1H,1H,2H,2H-perfluorooctyltrichlorosilane (CF3(CF2)5(CH2)2SiCl3) (FOTS) thin film on glass substrate wereinvestigated. Removal and desorption of FOTS were found to occur during alcohol rinsing/drying and low temperature annealing at 80oC,as evidenced by the increase in the FOTS oxygen/carbon (O/C) elemental ratio based on X-ray photoelectron spectroscopy study. Thesurfaces of FOTS thin film were reconstructed and a mechanism was proposed that accounts for the effect of solvent penetration throughdefect sites of FOTS thin film. The resulting topography increased the water static contact angle by as much as 26o whereas the contactangle hysteresis remained unchanged. A concurrent increase in water dynamic contact angles of 14owas also observed. In addition to thetopography effect, the increase in contact angles was also attributed to the changes of the proportions of hydrophobic and hydrophilicarea fraction (static and dynamic) and pinning effect (dynamic).