Applied Nanoscience (v.3, #3)

Thermoelectricity from wasted heat of integrated circuits by Hossain Fahad; Md. Hasan; Guodong Li; Muhammad Hussain (175-178).
We demonstrate that waste heat from integrated circuits especially computer microprocessors can be recycled as valuable electricity to power up a portion of the circuitry or other important accessories such as on-chip cooling modules, etc. This gives a positive spin to a negative effect of ever increasing heat dissipation associated with increased power consumption aligned with shrinking down trend of transistor dimension. This concept can also be used as an important vehicle for self-powered systems-on-chip. We provide theoretical analysis supported by simulation data followed by experimental verification of on-chip thermoelectricity generation from dissipated (otherwise wasted) heat of a microprocessor.
Keywords: Thermoelectricity; Wasted heat; Microprocessor; Self-powered; Systems-on-chip

To extend the work of binary fluid mixtures and their associated bridge-like structures, the adsorption of gas-like molecules (interacting via hard-sphere potentials) on self-assembled fluid channels was examined. We examined the morphological evolution of an initial random binary mixture under confinement of chemically patterned substrates with strong, long-range preferential attraction to the pure square-well component. Gas-like molecules were presumed to have a weak attraction to the square-well fluid. The morphology and corresponding density profiles revealed the underlying chemical and physical adsorption of gas-like molecules to off-strip voids and to the interface of the self-assembled fluid channels. The entropic effects drive the non-interaction hard-sphere molecules to assemble or reorganize in the voids left between the self-assembled square-well fluids. Such studies can help in the study of formation of nano-liquid structures and enhanced adsorption of gas-like molecules for storage purposes.
Keywords: Square-well fluid; Hard spheres; Entropic effect; Chemical and physical adsorption

Wet chemical synthesis and characterization of SnS2 nanoparticles by Sunil H. Chaki; M. P. Deshpande; Devangini P. Trivedi; Jiten P. Tailor; Mahesh D. Chaudhary; Kanchan Mahato (189-195).
The SnS2 nanoparticles were synthesized at room temperature by simple wet chemical method. Stannic chloride pentahydrate (SnCl4·5H2O) and thioacetamide (C2H5NS) were used as a source of Sn+4 ions and S−2 ions, respectively. The elemental composition of the as-synthesized SnS2 nanoparticles was determined by energy dispersive analysis of X-ray. The structure and lattice parameters were determined by X-ray diffraction. The crystallite size was determined from XRD pattern using Scherrer’s formula and Hall–Williamson plot. The transmission electron microscopy was employed to characterize the nanoparticles. The selected area electron diffraction pattern established the polycrystalline nature of SnS2 nanoparticles. Surface topography of nanoparticles was studied employing scanning electron microscopy (SEM). The bandgap determined from the UV–Vis–NIR spectrum of as-synthesized SnS2 nanoparticles showed blue shift in comparison with the bandgap of bulk SnS2. The photoluminescence spectra at five different excitation wavelengths 250, 300, 350, 400 and 450 nm showed two strong emission peaks at wavelengths 550 and 825 nm. The obtained results are discussed in details.
Keywords: SnS2 nanoparticles; Wet chemical method; Transmission electron microscopy; Scanning electron microscopy; Optical absorbance; Photoluminescence

Malaria is the most important parasitic disease, leading to annual death of about one million people and the Plasmodium falciparum develops resistant to well-established antimalarial drugs. The newest antiplasmodial drug from metal oxide nanoparticles helps in addressing this problem. Commercial nanoparticles such as Fe3O4, MgO, ZrO2, Al2O3 and CeO2 coated with PDDS and all the coated and non-coated nanoparticles were screened for antiplasmodial activity against P. falciparum. The Al2O3 nanoparticles (71.42 ± 0.49 μg ml−1) showed minimum level of IC50 value and followed by MgO (72.33 ± 0.37 μg ml−1) and Fe3O4 nanoparticles (77.23 ± 0.42 μg ml−1). The PDDS-Fe3O4 showed minimum level of IC50 value (48.66 ± 0.45 μg ml−1), followed by PDDS-MgO (60.28 ± 0.42 μg ml−1) and PDDS-CeO2 (67.06 ± 0.61 μg ml−1). The PDDS-coated metal oxide nanoparticles showed superior antiplasmodial activity than the non-PDDS-coated metal oxide nanoparticles. Statistical analysis reveals that, significant in vitro antiplasmodial activity (P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes showed no morphological changes in erythrocytes by the nanoparticles after 48 h of incubation. It is concluded from the present study that, the PDDS-Fe3O4 showed good antiplasmodial activity and it might be used for the development of antiplasmodial drugs.
Keywords: Antiplasmodial activity; IC50Metal oxide nanoparticles; Plasmodium falciparum

Effect of temperature on morphology of triethanolamine-assisted synthesized hydroxyapatite nanoparticles by Nagaprasad Puvvada; Pravas Kumar Panigrahi; Himani Kalita; Keka R. Chakraborty; Amita Pathak (203-209).
Hydroxyapatite (HA) nanoparticles have been synthesized using ortho-phosphoric acid as the source of PO43− ions, and calcium chloride, suitably complexed with triethanolamine, as the calcium source. The effect of temperature on the morphology of the product has been investigated. The chemical compositions of the samples have been established through Fourier transform infrared spectroscopy. This study reveals that A-type and B-type carbonate substitution are present in HA samples and the concentration of carbonate ions decrease with rise in temperature. Morphological analyses by TEM studies suggest that the average lengths and widths of the needle-shaped particles size increases with temperature up to 50 °C, while a morphological change of the particles from needle to spherical shape is observed on raising the temperature above 50 °C. This change in morphology has been assigned to the apparent solubility of HA at these temperatures, which has been studied by the determination of thermochemical properties of the reaction system by endpoint conductivity and electrophoretic mobility measurements.
Keywords: Hydroxyapatite; Temperature; Morphology; Endpoint conductivity

Effect of calcium oxalate on the photocatalytic degradation of Orange II on ZnO surface by S. Bassaid; B. Ziane; M. Badaoui; M. Chaib; D. Robert (211-215).
The photocatalytic degradation of aqueous solution of Orange II, has been investigated in the presence of ZnO catalyst with calcium oxalate as sacrificial agent. This study demonstrated that the performance of ZnO photocatalyst can be improved by addition of calcium oxalate. Results show that adsorption is an important parameter controlling the degradation phenomena. Indeed, the added oxalate causes a drop in the pH medium, what causes a better adsorption of Orange II on the ZnO surface. The effect of calcium oxalate is to increase the concentration of superoxides (O 2 ·− ) and hydroperoxides (HO2·) radicals, which are key intermediaries in the mechanism of photodegradation because of their powerful force of oxidation.
Keywords: ZnO; Photocatalysis; Organic pollutants; Orange II; Photocatalytic degradation; Sacrificial agent

The utilization of various plant resources for the biosynthesis of metallic nanoparticles is called green nanotechnology, and it does not utilize any harmful chemical protocols. The present study reports the plant-mediated synthesis of silver nanoparticles using the plant leaf extract of Coleus aromaticus, which acts as a reducing and capping agent. The silver nanoparticles were characterized by ultraviolet visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and the size of the silver nanoparticles is 44 nm. The bactericidal activity of the silver nanoparticles was carried out by disc diffusion method that showed high toxicity against Bacillus subtilis and Klebsiella planticola. Biosynthesis of silver nanoparticles by using plant resources is an eco-friendly, reliable process and suitable for large-scale production. Moreover, it is easy to handle and a rapid process when compared to chemical, physical, and microbe-mediated synthesis process.
Keywords: Biological synthesis; Silver nanoparticle; Electron microscopy; Coleus aromaticus ; UV–vis spectroscopy

Visible light water splitting using novel Al2O3/carbon cluster nanocomposite materials by H. Matsui; H. Miyazaki; A. Fujinami; S. Ito; M. Yoshihara; S. Karuppuchamy (225-228).
A novel nano-sized Al2O3/carbon cluster composite materials with and without doping of Pt nanoparticles are successfully prepared for the first time. The newly synthesized composites indeed very effective to split the water and produce H2 and O2 with the [H2]/[O2] ratios of ca.2.under visible light irradiation.
Keywords: Nanomaterials; Nanostructures; Semiconductors; Insulator

Green synthesis of silver nanoparticles using marine macroalga Chaetomorpha linum by R. Ragupathi Raja Kannan; R. Arumugam; D. Ramya; K. Manivannan; P. Anantharaman (229-233).
The present investigation demonstrates the formation of silver nanoparticles by the reduction of the aqueous silver metal ions during exposure to the seaweed (Chaetomorpha linum) extract. The silver nanoparticles obtained were characterized by UV–visible spectrum, FTIR and scanning electron microscopy. The characteristic absorption peak at 422 nm in UV–vis spectrum confirmed the formation of silver nanoparticles. The colour intensity at 422 nm increased with duration of incubation. The size of nanoparticles synthesized varied from 3 to 44 nm with average of ~30 nm. The FTIR spectrum of C. linum extract showed peaks at 1,020, 1,112, 1,325, 1,512, 1,535, 1,610, 1,725, 1,862, 2,924, 3,330 cm−1. The vibrational bands corresponding to the bonds such as –C=C (ring), –C–O, –C–O–C and C=C (chain) are derived from water-soluble compounds such as amines, peptides, flavonoids and terpenoids present in C. linum extract. Hence, it may be inferred that these biomolecules are responsible for capping and efficient stabilization. Since no synthetic reagents were used in this investigation, it is environmentally safe and have potential for application in biomedicine and agriculture.
Keywords: Marine algae; Green chemistry; Silver nanoparticles; Flavonoids

Conductive atomic force microscopy as a tool to reveal high ionising dose effects on ultra thin SiO2/Si structures by Richard Arinero; A. D. Touboul; M. Ramonda; C. Guasch; Y. Gonzalez-Velo; J. Boch; F. Saigné (235-240).
The electrical stress behaviour of non-irradiated and irradiated (2 to 7-nm thick) SiO2/Si structures is investigated using conductive-atomic force microscopy. A protocol based on the successive application of two ramped-voltage stresses (RVS) on each test point is performed. The environmental implementation conditions of such an experiment are then investigated. A statistical approach based on the use of Weibull distributions is also adopted. Before irradiation, for the thinnest samples, it is shown evidence of stress-induced trap-assisted tunnelling leading to a high decrease in threshold voltages on the second RVS. After high-dose X-ray irradiations, the first RVS exhibit voltage-shift effects increasing with the oxide film thickness, whereas for the second RVS, no additional effect is observed. The high locality of these measurements, sensitive to a few tens of trapped charges, is therefore demonstrated and constitutes a new step towards a better understanding of oxide degradation mechanisms due to radiation effects.
Keywords: Conductive-AFM (C-AFM); Weibull statistic; Ramped voltage stress; Nano I–V curves; Ultra-thin oxide films; SiO2/Si structures; Oxide reliability

Electrical, magnetic, and corrosion resistance properties of TiO2 nanotubes filled with NiFe2O4 quantum dots and Ni–Fe nanoalloy by Mohamed Bahgat; Ahmed A. Farghali; Ahmed F. Moustafa; Mohamed H. Khedr; Mohassab Y. Mohassab-Ahmed (241-249).
This work was carried out as an integral part of a project aiming to improve the catalytic, electrical, magnetic, and mechanical properties of synthesized TiO2NTs filled with metal ferrites. TiO2 nanotubes in the anatase-phase (TiO2NTs) were prepared using a hydrothermal method followed by ion exchange and phase transformation. The obtained TiO2NTs were filled with NiFe2O4 quantum dots (QDs) and then reacted at 600 °C in a reducing atmosphere to produce TiO2NTs filled with Ni–Fe nanoalloy. The effect of the TiO2NTs’ coating on the dissolution rate of Ni–Fe nanoalloy in 0.5 M HCl solution was monitored chemically using a weight-loss technique that was performed at different temperatures. The TiO2NTs’ coating exhibited high protective performance and amazing corrosion resistance. The magnetic properties of the TiO2NTs filled with NiFe2O4 QDs and Ni–Fe nanoalloy compacts were analyzed by a vibrating sample magnetometer. The electrical conductivity-temperature dependence of anatase TiO2NTs, anatase TiO2NTs filled with NiFe2O4 quantum dots, anatase TiO2NTs filled with Ni–Fe nanoalloy, and NiFe2O4 was measured in the temperature range of 25–850 °C. The conductivity increased with temperature, indicating the semiconductor-like nature of the sample. During cooling, the conductivity retains values higher than that obtained during heating.
Keywords: Corrosion resistance; DC conductivity; Filled TiO2NTs; Magnetic properties; Quantum dots and TiO2NTs

Adsorption of methyl green dye onto multi-walled carbon nanotubes decorated with Ni nanoferrite by Mohamed Bahgat; Ahmed Ali Farghali; Waleed El Rouby; Mohamed Khedr; Mohassab Y. Mohassab-Ahmed (251-261).
This research was carried out to evaluate the capability of multi-walled carbon nanotubes (CNTs) and NiFe2O4-decorated multi-walled carbon nanotubes (NiFe2O4-CNTs) toward waste water treatment relevant to organic dyes. CNTs were prepared via chemical vapor deposition method. NiFe2O4-CNTs were prepared by in-situ chemical precipitation of metal hydroxides followed by hydrothermal processing. The samples were characterized using XRD and TEM. The adsorption efficiency of CNTs and NiFe2O4-CNTs of methyl green dye at various temperatures was examined. The adsorbed amount increased with the CNTs and NiFe2O4-CNTs dosage. The linear correlation coefficients and standard deviations of Langmuir and Freundlich isotherms were determined. It was found that Langmuir isotherm fitted the experimental results well in both adsorption cases n of methyl green onto CNTs and NiFe2O4-CNTs. Kinetics analyses were conducted using pseudo first-order, second-order and the intraparticle diffusion models. The results showed that the adsorption kinetics was controlled by a pseudo second-order model for adsorption of methyl green onto CNTs and best controlled by pseudo first-order in case of NiFe2O4-CNTs. Changes in the free energy of adsorption (ΔG°), enthalpy (ΔH°), entropy (ΔS°), and the activation energy (Ea) were determined. The ΔH°, ΔG° and Ea values indicated that the adsorption of methyl green onto MWCNTs and NiFe2O4-MWCNTs was physisorption.
Keywords: Carbon nanotubes; Decorated CNT; NiFe2O4Adsorption; Methyl green; Isotherm

C14TAB-assisted cerium oxide (CeO2) mesocrystals have been synthesized via wet chemical route. XRD, SEM, AFM, EDS, FTIR, Raman, UV–vis and PL spectroscopy were employed to characterize the crystal phase, morphology, chemical composition and optical properties of the CeO2 mesocrystals. The experimental results showed that the product owned mesocrystal structure with self-assembly cubic architecture in the presence of C14TAB as a template. The growth mechanism of CeO2 mesocrystals has been predicted to explain the formation of CeO2 mesocrystals. CeO2 mesocrystals exhibit a very strong violet/blue emission centered at 421 nm and a weak green luminescence emission at around 524 nm.
Keywords: Mesocrystals; C14TAB; AFM; Self-assembly