Journal of Nanoscience http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. FTIR and EPR Studies of Nickel Substituted Nanostructured Mn Zn Ferrite Mon, 22 Sep 2014 00:00:00 +0000 http://www.hindawi.com/journals/jns/2014/815385/ The spinel ferrite system is prepared by coprecipitation method. XRD analysis confirms the formation of ferrite phase in all the samples. The FTIR spectra of all the samples show two main absorption bands below 1000 cm−1. FTIR studies reveal cationic exchange between A site and B site. The magnetic moment calculated from EPR studies is lower when compared to the theoretical values. This confirms the existence of noncollinear magnetic structure arising due to spin canting at B site. C. Venkataraju and R. Paulsingh Copyright © 2014 C. Venkataraju and R. Paulsingh. All rights reserved. Landauer-Datta-Lundstrom Generalized Transport Model for Nanoelectronics Wed, 17 Sep 2014 09:25:41 +0000 http://www.hindawi.com/journals/jns/2014/725420/ The Landauer-Datta-Lundstrom electron transport model is briefly summarized. If a band structure is given, the number of conduction modes can be evaluated and if a model for a mean-free-path for backscattering can be established, then the near-equilibrium thermoelectric transport coefficients can be calculated using the final expressions listed below for 1D, 2D, and 3D resistors in ballistic, quasiballistic, and diffusive linear response regimes when there are differences in both voltage and temperature across the device. The final expressions of thermoelectric transport coefficients through the Fermi-Dirac integrals are collected for 1D, 2D, and 3D semiconductors with parabolic band structure and for 2D graphene linear dispersion in ballistic and diffusive regimes with the power law scattering. Yuriy Kruglyak Copyright © 2014 Yuriy Kruglyak. All rights reserved. Growth of Horizontal Nanopillars of CuO on NiO/ITO Surfaces Thu, 28 Aug 2014 09:48:17 +0000 http://www.hindawi.com/journals/jns/2014/635308/ We have demonstrated hydrothermal synthesis of rectangular pillar-like CuO nanostructures at low temperature (~60°C) by selective growth on top of NiO porous structures film deposited using chemical bath deposition method at room temperature using indium tin oxide (ITO) coated glass plate as a substrate. The growth of CuO not only filled the NiO porous structures but also formed the big nanopillars/nanowalls on top of NiO surface. These nanopillars could have significant use in nanoelectronics devices or can also be used as p-type conducting wires. The present study is limited to the surface morphology studies of the thin nanostructured layers of NiO/CuO composite materials. Structural, morphological, and absorption measurement of the CuO/NiO heterojunction were studied using state-of-the-art techniques like X-ray diffraction (XRD), transmission electron microscopy (SEM), atomic force microscopy (AFM), and UV spectroscopy. The CuO nanopillars/nanowalls have the structure in order of (5 ± 1.0) μm × (2.0 ± 0.3) μm; this will help to provide efficient charge transport in between the different semiconducting layers. The energy band gap of NiO and CuO was also calculated based on UV measurements and discussed. Siddharth Joshi, Mrunmaya Mudigere, L. Krishnamurthy, and G. L. Shekar Copyright © 2014 Siddharth Joshi et al. All rights reserved. The Effect of DNA and Sodium Cholate Dispersed Single-Walled Carbon Nanotubes on the Green Algae Chlamydomonas reinhardtii Tue, 26 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/jns/2014/419382/ Increasing use of single-walled carbon nanotubes (SWCNTs) will lead to their increased release into the environment. Previous work has shown negative effects of SWCNT on growth and survival of model organisms. The aim of the current study was to determine the effect of SWCNT well-dispersed by either DNA or sodium cholate (SC) on the unicellular green algae Chlamydomonas reinhardtii in stagnant water conditions. Growth measurements were taken up to ten days for algae treated with varied levels of DNA:SWCNT or SC:SWCNT or controls, and chlorophyll content after 10 days was determined. Results show no effect on either growth or chlorophyll content of algae at any concentration or duration. This is in contradiction to prior work showing toxicity of SWCNT to environmental model organisms. Ryan M. Williams, Hannah K. Taylor, Jackson Thomas, Zachary Cox, Bridget D. Dolash, and Letha J. Sooter Copyright © 2014 Ryan M. Williams et al. All rights reserved. Self-Passivation by Fluorine Plasma Treatment and Low-Temperature Annealing in SiGe Nanowires for Biochemical Sensors Wed, 11 Jun 2014 10:37:20 +0000 http://www.hindawi.com/journals/jns/2014/961720/ Nanowires are widely used as highly sensitive sensors for electrical detection of biological and chemical species. Modifying the band structure of strained-Si metal-oxide-semiconductor field-effect transistors by applying the in-plane tensile strain reportedly improves electron and hole mobility. The oxidation-induced Ge condensation increases the Ge fraction in a SiGe-on-insulator (SGOI) and substantially increases hole mobility. However, oxidation increases the number of surface states, resulting in hole mobility degradation. In this work, 3-aminopropyltrimethoxysilane (APTMS) was used as a biochemical reagent. The hydroxyl molecule on the oxide surface was replaced by the methoxy groups of the APTMS molecule. We proposed a surface plasma treatment to improve the electrical properties of SiGe nanowires. Fluorine plasma treatment can result in enhanced rates of thermal oxidation and speed up the formation of a self-passivation oxide layer. Like a capping oxide layer, the self-passivation oxide layer reduces the rate of follow-up oxidation. Preoxidation treatment also improved the sensitivity of SiGe nanowires because the Si-F binding was held at a more stable interface state compared to bare nanowire on the SiGe surface. Additionally, the sensitivity can be further improved by either the N2 plasma posttreatment or the low-temperature postannealing due to the suppression of outdiffusion of Ge and F atoms from the SiGe nanowire surface. Kow-Ming Chang, Chiung-Hui Lai, Chu-Feng Chen, Po-Shen Kuo, Yi-Ming Chen, Tai-Yuan Chang, Allen Jong-Woei Whang, Yi-Lung Lai, Huai-Yi Chen, and Ing-Jar Hsieh Copyright © 2014 Kow-Ming Chang et al. All rights reserved. FTIR and Electrical Study of Dysprosium Doped Cobalt Ferrite Nanoparticles Sun, 18 May 2014 12:46:53 +0000 http://www.hindawi.com/journals/jns/2014/862415/ We have studied the role of Dy3+ doping on the XRD, TEM, FTIR, and dielectric and electrical properties of CoFe2O4 at room temperature. Cubic spinel phase of CoFe2−xDyxO4 ( = 0.00, 0.05, 0.10, and 0.15) was synthesized by using different sintering temperatures (300, 500, 700, and 900°C). The two absorption bands ν1 and ν2 are observed in Fourier transform infrared spectroscopy (FTIR) spectra corresponding to the tetrahedral and octahedral sites, which show signature of spinel structure of the sample. For the sample sintered at 300°C, the dielectric constant is almost unchanged with the frequency at the particular concentrations of = 0.00 and 0.05. Similar result is obtained for the sample sintered at 500°C ( = 0.10, 0.15), 700°C ( = 0.05, 0.10, and 0.15), and 900°C ( = 0.05, 0.10). An increase in the dielectric constant was observed for the undoped cobalt ferrite sintered at 500, 700, and 900°C. The values of electrical resistivity of the materials vary from ~105 to 109 Ω-cm. Hemaunt Kumar, Jitendra Pal Singh, R. C. Srivastava, P. Negi, H. M. Agrawal, and K. Asokan Copyright © 2014 Hemaunt Kumar et al. All rights reserved. Quantifying the Aggregation Factor in Carbon Nanotube Dispersions by Absorption Spectroscopy Tue, 29 Apr 2014 06:23:04 +0000 http://www.hindawi.com/journals/jns/2014/328627/ Absorption spectroscopy in the ultraviolet-visible-near infrared (UV-Vis-NIR) wavelength region has been used to quantify the aggregation factor of single-walled carbon nanotubes (SWCNTs) in liquid media through a series of controlled experiments. SWCNT bundles are dispersed in selected solvents using a calibrated ultrasonicator, which helps in determining the true amount of energy used in the exfoliation process. We also establish the selectivity of the centrifugation process, under the conditions used, in removing the nanotube aggregates as a function of the sonication time and the dispersion solvent. This study, along with the calibration of the sonication process, is shown to be very important for measuring the true aggregation factor of SWCNTs through a modified approach. We also show that the systematic characterization of SWCNT dispersions by optical spectroscopy significantly contributes to the success of dielectrophoresis (DEP) of nanotubes at predefined on-chip positions. The presence of individually dispersed SWCNTs in the dispersions is substantiated by dielectrophoretic assembly and post-DEP electromechanical measurements. Hari Pathangi, Philippe M. Vereecken, Alexander Klekachev, Guido Groeseneken, and Ann Witvrouw Copyright © 2014 Hari Pathangi et al. All rights reserved. Solvent-Mediated Eco-Friendly Synthesis and Characterization of Monodispersed Bimetallic Ag/Pd Nanocomposites for Sensing and Raman Scattering Applications Sun, 13 Apr 2014 13:40:22 +0000 http://www.hindawi.com/journals/jns/2014/762453/ The solvent-mediated eco-friendly monodispersed Ag/Pd bimetallic nanocomposites (BNCs) having thick core and thin shell have been prepared through novel green chemical solvent reduction method. Reducing solvent, dimethyl formamide (DMF) is employed for the controlled green synthesis. Characterization of the synthesized Ag/Pd BNCs has been done by x-ray diffraction (XRD) studies, high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray analysis (EDX), and high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED) pattern. The nature of the interaction of L-cysteine with Ag/Pd BNCs has been studied by using surface plasmon spectroscopy, Fourier transform-infrared spectroscopy (FT-IR), cyclic voltammetry (CV), and theoretical methods. G. Sathiyadevi, B. Loganathan, and B. Karthikeyan Copyright © 2014 G. Sathiyadevi et al. All rights reserved. Modeling Replenishment of Ultrathin Liquid Perfluoropolyether Z Films on Solid Surfaces Using Monte Carlo Simulation Sun, 06 Apr 2014 09:00:05 +0000 http://www.hindawi.com/journals/jns/2014/104137/ Applying the reptation algorithm to a simplified perfluoropolyether Z off-lattice polymer model an NVT Monte Carlo simulation has been performed. Bulk condition has been simulated first to compare the average radius of gyration with the bulk experimental results. Then the model is tested for its ability to describe dynamics. After this, it is applied to observe the replenishment of nanoscale ultrathin liquid films on solid flat carbon surfaces. The replenishment rate for trenches of different widths (8, 12, and 16 nms for several molecular weights) between two films of perfluoropolyether Z from the Monte Carlo simulation is compared to that obtained solving the diffusion equation using the experimental diffusion coefficients of Ma et al. (1999), with room condition in both cases. Replenishment per Monte Carlo cycle seems to be a constant multiple of replenishment per second at least up to 2 nm replenished film thickness of the trenches over the carbon surface. Considerable good agreement has been achieved here between the experimental results and the dynamics of molecules using reptation moves in the ultrathin liquid films on solid surfaces. M. S. Mayeed and T. Kato Copyright © 2014 M. S. Mayeed and T. Kato. All rights reserved. Characterization of Erbium Substituted Yttrium Iron Garnet Films Prepared by Sol-Gel Method Sun, 06 Apr 2014 08:32:49 +0000 http://www.hindawi.com/journals/jns/2014/158946/ Yttrium iron garnet (YIG) thin films substituted erbium ions (Er+3) Er0.4Y2.6Fe5O12 films were prepared by a sol-gel method at different temperatures which varied from 800 to 1000°C for 2 hours in air. Magnetic and microstructural properties of the films were characterized with X-ray diffraction (XRD), the field emission scanning electron microscopy (FESEM), and vibrating sample magnetometer (VSM). The XRD patterns of the sample have only peaks of the garnet structure. The lattice constants decrease, while the particle size increases from 51 to 85 nm as the annealing temperature increases with average in thickness of 300 nm. The saturation magnetization and the coercivity of the samples increased from 26 (emu/cc) and 28 Oe for the film annealed at 800°C to 76 (emu/cc) and 45 Oe for film annealed at 1000°C, respectively. Ramadan E. Shaiboub and N. B. Ibrahim Copyright © 2014 Ramadan E. Shaiboub and N. B. Ibrahim. All rights reserved. Simulations of the Light Scattering Properties of Metal/Oxide Core/Shell Nanospheres Sun, 06 Apr 2014 07:31:34 +0000 http://www.hindawi.com/journals/jns/2014/407670/ Given the importance of the optical properties of metal/dielectric core/shell nanoparticles, in this work we focus our attention on the light scattering properties, within the Mie framework, of some specific categories of these noteworthy nanostructures. In particular, we report theoretical results of angle-dependent light scattering intensity and scattering efficiency for Ag/Ag2O, Al/Al2O2, Cu/Cu2O, Pd/PdO, and Ti/TiO2 core/shell nanoparticles as a function of the core radius/shell thickness ratio and on a relative comparison. The results highlight the light scattering characteristics of these systems as a function of the radius/shell thickness ratio, helping in the choice of the more suitable materials and sizes for specific applications (i.e., dynamic light scattering for biological and molecular recognition, increasing light trapping in thin-film silicon, organic solar cells for achieving a higher photocurrent). F. Ruffino, G. Piccitto, and M. G. Grimaldi Copyright © 2014 F. Ruffino et al. All rights reserved. Modulation of Carbon Nanotube Metal Contacts in Gaseous Hydrogen Environment Thu, 27 Mar 2014 15:56:29 +0000 http://www.hindawi.com/journals/jns/2014/404519/ Carbon nanotubes (CNTs), contacted by electrodeposited Pd0.59Ni0.41 alloys, are characterised using electrical measurements and Raman spectroscopy. The high workfunctions of Nickel and Palladium form an ohmic contact with the CNT valence band, but the contact properties change on Hydrogen exposure due to a reduction in the PdNi workfunction and the realignment of the PdNi Fermi level with the CNT band structure. A PdNi contacted semiconducting CNT exhibited significantly lower currents after Hydrogen exposure while a metallic CNT exhibited a small current increase. The semiconducting and metallic natures of the CNTs are confirmed by their Raman spectra. This study demonstrates a technique for modulating the PdNi-CNT contact and differentiating between semiconducting and metallic CNTs via contact modulation. It also provides experimental evidence of the theoretical allocation of features in the CNT Raman spectra. A. R. Usgaocar, Harold M. H. Chong, and C. H. de Groot Copyright © 2014 A. R. Usgaocar et al. All rights reserved. Study of the Light Coupling Efficiency of OLEDs Using a Nanostructured Glass Substrate Mon, 24 Mar 2014 09:00:14 +0000 http://www.hindawi.com/journals/jns/2014/258937/ We study theoretically the enhancement of the light extraction from an OLED (Organic Light-Emitting Diode) with nanoair-bubbles embedded inside a glass substrate. Due to such a nanostructure inside the substrate, the critical angle which limits the light extraction outside the substrate from the OLED is increased. The theoretical results show that the nanoair bubbles near by the substrate surface can improve the efficiency of the light extraction by 7%. Such a substrate may also be suitable for photovoltaic cells or display screens. Min Won Lee, Siegfried Chicot, Chii-Chang Chen, Mahmoud Chakaroun, Getachew Ayenew, Alexis Fischer, and Azzedine Boudrioua Copyright © 2014 Min Won Lee et al. All rights reserved. Formulation of a Novel Nanoemulsion System for Enhanced Solubility of a Sparingly Water Soluble Antibiotic, Clarithromycin Sun, 23 Mar 2014 07:14:00 +0000 http://www.hindawi.com/journals/jns/2014/268293/ The sparingly water soluble property of majority of medicinally significant drugs acts as a potential barrier towards its utilization for therapeutic purpose. The present study was thus aimed at development of a novel oil-in-water (o/w) nanoemulsion (NE) system having ability to function as carrier for poorly soluble drugs with clarithromycin as a model antibiotic. The therapeutically effective concentration of clarithromycin, 5 mg/mL, was achieved using polysorbate 80 combined with olive oil as lipophilic counterion. A three-level three-factorial central composite experimental design was utilized to conduct the experiments. The effects of selected variables, polysorbate 80 and olive oil content and concentration of polyvinyl alcohol, were investigated. The particle size of clarithromycin for the optimized formulation was observed to be 30 nm. The morphology of the nanoemulsion was explored using transmission electron microscopy (TEM). The emulsions prepared with the optimized formula demonstrated good physical stability during storage at room temperature. Antibacterial activity was conducted with the optimized nanoemulsion NESH 01 and compared with free clarithromycin. Zone of inhibition was larger for NESH 01 as compared to that with free clarithromycin. This implies that the solubility and hence the bioavailability of clarithromycin has increased in the formulated nanoemulsion system. Stuti Vatsraj, Kishor Chauhan, and Hilor Pathak Copyright © 2014 Stuti Vatsraj et al. All rights reserved. Microstructural and Electrochemical Properties of rf-Sputtered LiFeO2 Thin Films Thu, 13 Mar 2014 12:05:18 +0000 http://www.hindawi.com/journals/jns/2014/173845/ Lithium iron oxide (LiFeO2) thin films have been deposited by rf-magnetron sputtering technique and microstructural and electrochemical properties were studied. The films deposited at a substrate temperature 250°C with subsequent post annealing at 500°C for 4 h exhibited cubic rock-salt structure with Fm3m space group. The films exhibited well-defined oxidation and reduction peaks suggesting complete reversibility upon cycling. The as-deposited films exhibited an initial discharge capacity 15 Ah/cm2·m, whereas the films post annealed at 500°C for 4 h in controlled oxygen environment exhibited 31 Ah/cm2·m. P. Rosaiah and O. M. Hussain Copyright © 2014 P. Rosaiah and O. M. Hussain. All rights reserved. Biosynthesis and Characterization of Gold and Silver Nanoparticles Using Milk Thistle (Silybum marianum) Seed Extract Wed, 12 Mar 2014 08:27:14 +0000 http://www.hindawi.com/journals/jns/2014/905404/ Biogenic synthesis of gold and silver nanoparticles from aqueous solutions using milk thistle (Silybum marianum) seed extract as reducing and stabilizing agent has been reported. Formation and stabilization of nanoparticles were monitored using surface plasmon resonance (SPR) bands of UV-Vis spectroscopy. Morphology of gold and silver nanoparticles was investigated using X-ray diffraction, high-resolution transmission electron microscopy with selected area electron diffraction analysis, and dynamic light scattering. Fourier transform-infrared spectroscopy was employed to identify the possible biomolecules responsible for the reduction and stabilization of nanoparticles. R. Gopalakrishnan and K. Raghu Copyright © 2014 R. Gopalakrishnan and K. Raghu. All rights reserved. Effect of Reaction Rate and Calcination Time on Nanoparticles Tue, 11 Mar 2014 12:51:48 +0000 http://www.hindawi.com/journals/jns/2014/909267/ The properties of CaNb2O6 nanoparticles synthesized by coprecipitation method under controlled reaction rate and extended calcination time were studied. Analysis of the X-ray diffraction pattern shows single orthorhombic phase of the material with lattice parameters:  Å,  Å, and  Å. The morphology and size of particles was found to be improved due to the controlled reaction rate and extended calcination time. The average sizes of the particles were estimated as 40 nm and 90 nm for sintering temperatures 650°C and 800°C, respectively. The material was found to possess dielectric constant which is inversely proportional to the frequency. Surprisingly, the material shows ferroelectric behavior, the possible origin of which is discussed here. C. M. Dudhe and S. B. Nagdeote Copyright © 2014 C. M. Dudhe and S. B. Nagdeote. All rights reserved. Degradation of Tannic Acid Using TiO2 Nanotubes as Electrocatalyst Sun, 05 Jan 2014 11:55:08 +0000 http://www.hindawi.com/journals/jns/2014/481023/ Structured TiO2 nanotubes were grown on 2 mm thick titanium sheet by anodization of titanium in ethylene glycol medium containing 0.025 M NaF. The morphology of TiO2 nanotubes (TNT) was characterized using field emission scanning electron microscope. The potential of TNT as anode and also as photocatalyst for the degradation of tannic acid was studied. The mineralization of tannic acid was measured in terms Total Organic Carbon (TOC). Only 50% of TOC could be removed by exposing the tannic acid solution to UV-radiation (photolysis), whereas it was improved to 70% by electrooxidation (EO) using TNT as anode. Maximum degradation of 83% was achieved when electrooxidation was conducted under the influence of UV-radiation (photoelectrocatalytic process (PEC)). Among the electrolytes tried, Na2SO4 was observed to be very effective for the degradation of tannic acid. The kinetics of tannic acid degradation by photoelectrocatalytic process was found to follow zero-order rate expression. N. Lakshmi Kruthika, G. Bhaskar Raju, and S. Prabhakar Copyright © 2014 N. Lakshmi Kruthika et al. All rights reserved. Phytochemical Synthesis and Preliminary Characterization of Silver Nanoparticles Using Hesperidin Thu, 26 Dec 2013 18:14:40 +0000 http://www.hindawi.com/journals/jns/2013/126564/ This paper is the first of its kind for development of rapid and ecofriendly method for synthesis of silver nanoparticles from aqueous solution of silver nitrate using the flavonoid “hesperidin” and optimization of the methodology. There is formation of stable spherical silver nanoparticles in the size range of 20–40 nm. Optimization of methodology in terms of concentration of reactants and pH of the reaction mixture reduced the reaction time for silver nanoparticle formation to 2 mins. Silver nanoparticles (AgNPs) were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). UV-vis spectroscopy derived spectrum demonstrated a peak of 430 nm which corresponds to the plasmon absorbance of silver nanoparticles. Transmission electron microscopy revealed spherical shaped silver nanoparticles in the size range of 20–40 nm. Anish Stephen and Sankar Seethalakshmi Copyright © 2013 Anish Stephen and Sankar Seethalakshmi. All rights reserved. Effects of Surface Treatments of Montmorillonite Nanoclay on Cure Behavior of Diglycidyl Ether of Bisphenol A Epoxy Resin Tue, 24 Dec 2013 08:15:19 +0000 http://www.hindawi.com/journals/jns/2013/864141/ Diglycidyl ether of Bisphenol A (DGEBA) based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT) nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied using a variety of techniques. Primary focus of this study was to investigate influence of different surface modifications of MMT nanoclay on rheological properties and cure behavior of SC-15 epoxy resin. By adding MMT to SC-15 epoxy resin, chemistry of the epoxy is altered leading to changes in rheological properties and ultimately enthalpy and activation energy of reactions. Addition of Nanomer I.28E delayed gelation, while Cloisite 10A and 30B accelerated gelation, regardless of the curing temperature. Activation energy of reaction was lower with the addition of Nanomer I.28E and Cloisite 10A and higher for Cloisite 30B compared to neat SC-15 epoxy composite. Alfred Tcherbi-Narteh, Mahesh V. Hosur, Eldon Triggs, and Shaik Jelaani Copyright © 2013 Alfred Tcherbi-Narteh et al. All rights reserved. The Effect of Nanoparticles Percentage on Mechanical Behavior of Silica-Epoxy Nanocomposites Sun, 22 Dec 2013 15:25:09 +0000 http://www.hindawi.com/journals/jns/2013/275037/ Silica-epoxy nanocomposites are very common among nanocomposites, which makes them very important. Several researchers have studied the effect of nanoparticle’s size, shape, and loading on mechanical behavior of silica-epoxy nanocomposites. This paper reviews the most important research done on the effect of nanoparticle loading on mechanical properties of silica-epoxy nanocomposites. While the main focus is the tensile behavior of nanocomposite, the compressive behavior and flexural behavior were also reviewed. Finally, some of the published experimental data were combined in the graphs, using dimensionless parameters. Later, the best fitted curves were used to derive some empirical formulas for mechanical properties of silica-epoxy nanocomposites as functions of weight or volume fraction of nanoparticles. Md Saiful Islam, Reza Masoodi, and Hossein Rostami Copyright © 2013 Md Saiful Islam et al. All rights reserved. Two-Dimensional Variable Property Conjugate Heat Transfer Simulation of Nanofluids in Microchannels Mon, 16 Dec 2013 08:42:37 +0000 http://www.hindawi.com/journals/jns/2013/217382/ Laminar two-dimensional forced convective heat transfer of CuO-water and Al2O3-water nanofluids in a horizontal microchannel has been studied numerically, considering axial conduction effects in both solid and liquid regions and variable thermal conductivity and dynamic viscosity. The results show that using nanoparticles with higher thermal conductivities will intensify enhancement of heat transfer characteristics and slightly increases shear stress on the wall. The obtained results show more steep changes in Nusselt number for lower diameters and also higher values of Nusselt number by decreasing the diameter of nanoparticles. Also, by utilizing conduction number as the criterion, it was concluded from the results that adding nanoparticles will intensify the axial conduction effect in the geometry considered. A. Ramiar and A. A. Ranjbar Copyright © 2013 A. Ramiar and A. A. Ranjbar. All rights reserved. One-Step Synthesis of Colloidal Quantum Dots of Iron Selenide Exhibiting Narrow Range Fluorescence in the Green Region Mon, 09 Dec 2013 13:09:10 +0000 http://www.hindawi.com/journals/jns/2013/804290/ The instantaneous isolation of green fluorescent colloidal quantum dots of iron selenide capped with biocompatible oleic acid is reported in this study. These iron-containing quantum dots also serve as a safe alternative to the conventionally used metal-chalcogenide systems in which the heavy metal component is usually toxic. The isolated colored colloidal solutions exhibited intense green fluorescence on exposure to ultraviolet light, which was also confirmed by photoluminescence spectroscopy. The isolated product was subjected to dynamic light scattering and transmission electron microscopy, and the particles were found to exhibit spherical morphology with an average diameter of 6–8 nm, confirming the isolation of quantum dots. The isolated iron selenide quantum dots have promising potential towards bioimaging and sensing, due to the biocompatible coating of oleic acid and iron, which also allows possibility of further chemical derivatization. Pradyumna Mulpur, Tanu Mimani Rattan, and Venkataramaniah Kamisetti Copyright © 2013 Pradyumna Mulpur et al. All rights reserved. Therapeutic Potential of Biologically Reduced Silver Nanoparticles from Actinomycete Cultures Mon, 21 Oct 2013 15:50:07 +0000 http://www.hindawi.com/journals/jns/2013/940719/ Silver nanoparticles are applied in nanomedicine from time immemorial and are still used as powerful antibiotic and anti-inflammatory agents. Antibiotics produced by actinomycetes are popular in almost all the therapeutic measures, and this study has proven that these microbes are also helpful in the biosynthesis of silver nanoparticles with good surface and size characteristics. Silver can be synthesized by various chemical methodologies, and most of them have turned to be toxic. This study has been successful in isolating the microbes from polluted environment, and subjecting them to the reduction of silver nanoparticles, characterizing the nanoparticles by UV spectrophotometry and transmission electron microscopy. The nanoparticles produced were tested for their antimicrobial property, and the zone of inhibition was greater than those produced by their chemically synthesized counterparts. Actinomycetes, helpful in bioremediating heavy metals, are useful for the production of metallic nanoparticles. The biosynthesized silver nanoparticles loaded with antibiotics prove to be better in killing the pathogens and have opened up new areas for developing nanobiotechnological research based on microbial applications. M. K. Sukanya, K. A. Saju, P. K. Praseetha, and G. Sakthivel Copyright © 2013 M. K. Sukanya et al. All rights reserved. Effect of Samarium Substitution on the Structural and Magnetic Properties of Nanocrystalline Cobalt Ferrite Mon, 30 Sep 2013 17:36:46 +0000 http://www.hindawi.com/journals/jns/2013/524380/ A series of samarium-substituted cobalt ferrites ( with , 0.05, 0.10, 0.15, 0.20, 0.25) was synthesized by the sol-gel method. The structural characterizations of all the prepared samples were done using XRD and FTIR. These studies confirmed the formation of single-phase spinel structure in all the compositions. The increase in the value of lattice parameter with increase in samarium concentration suggests the expansion of unit cell. The Hall-Williamson analysis is used for estimating the average crystallite size and lattice strain induced due to the substitution of samarium in the prepared samples. Crystallinity and the crystallite size are observed to increase with the concentration of samarium. The surface morphology and particle size of a typical sample were determined using SEM and TEM respectively. The substitution of samarium strongly influences the magnetic characteristics, and this is confirmed from the magnetization measurements at room temperature. Sheena Xavier, Smitha Thankachan, Binu P. Jacob, and E. M. Mohammed Copyright © 2013 Sheena Xavier et al. All rights reserved. Helical Nanostructure of Achiral Silver p-Tolylacetylide Molecules Thu, 26 Sep 2013 10:09:14 +0000 http://www.hindawi.com/journals/jns/2013/545430/ Silver p-tolylacetylide is an achiral molecule; however, its nanostructure has been found to consist of twisted nanoribbons. The twisted ribbon is a helicoid that combines translation and perpendicular rotation along the ribbon axis. A helix, a typical chiral structure, can be created by the aggregation of achiral molecules, and the recrystallization conditions control the twist of the nanoribbons. Therefore, the recrystallization controls the chirality. Ken Judai, Yoshikiyo Hatakeyama, and Junichi Nishijo Copyright © 2013 Ken Judai et al. All rights reserved. Charge Transport in 1-D Nanostructured CdS Dye Sensitized Solar Cell Mon, 23 Sep 2013 11:28:26 +0000 http://www.hindawi.com/journals/jns/2013/167517/ Charge transport in eosin yellow sensitized CdS 1-D nanostructures is studied. Direct conduction pathway for electron transport in nanowires enhances in CdS nanowires compared to nanorods and nanoparticles. characterization of nanowires results in improved efficiency of 0.184% due to fewer interparticle connections. Increase in is observed by coating CdS 1-D nanostructures on TiO2 substrate which reduces rate of recombination and photocorrosive nature of CdS photoanodes. Enhancement in efficiency up to 0.501% is achieved for CdS 1-D nanostructures DSSCs on TiO2 substrate. M. Ragam, N. Sankar, and K. Ramachandran Copyright © 2013 M. Ragam et al. All rights reserved. Linear Sensing Response to Ethanol by Indium Oxide Nanoparticle Layers Thu, 19 Sep 2013 08:32:38 +0000 http://www.hindawi.com/journals/jns/2013/540741/ Indium oxide nanoparticles having well-defined particle sizes were synthesized using a chemical capping method. These nanoparticles were used for making the nanoparticle layers without altering the size and morphology of these particles. These nanoparticles and nanoparticle layers were characterized using XRD, TEM, HRTEM and AFM. The ethanol sensing behavior of the nanoparticle layers were studied at different ethanol concentrations. It was observed that the sensor response was linear to the ethanol concentration in the range of 10–1000 ppm. The ethanol sensing behavior has been explained on the basis of the creation of a depletion region due to the adsorbed oxygen and release of the electron in the conduction band in the presence of ethanol (as it takes away the adsorbed oxygen). The explanation has been supported by EDAX results. Vidya N. Singh and Ganesan Partheepan Copyright © 2013 Vidya N. Singh and Ganesan Partheepan. All rights reserved. Comparative Assessment of Antimicrobial Efficiency of Ionic Silver, Silver Monoxide, and Metallic Silver Incorporated onto an Aluminum Oxide Nanopowder Carrier Tue, 17 Sep 2013 14:08:17 +0000 http://www.hindawi.com/journals/jns/2013/263583/ The present paper provides comparative assessment of antimicrobial efficiency of ionic silver (Ag+), silver monoxide (Ag2O), and metallic silver (Ag) incorporated onto an aluminum oxide nanopowder carrier (Al2O3). The deposition of Ag+ ions, Ag2O nanoparticles, and Ag nanoparticles on an different phases of aluminum oxide nanopowder carrier was realized using consecutive stages of dry sol-gel method. The Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders were widely characterized qualitatively and quantitatively by SEM, physical nitrogen sorption and XRD analyses. Results indicate that the Al2O3 nanopowders added with Ag+, Ag2O, and Ag, apart from phase composition, were not differing considerably from one another in terms of their morphology and physical properties. However, nanopowders of Al2O3-Ag were more agglomerated than Al2O3-Ag2O and Al2O3-Ag+ nanopowders. The antibacterial activity of the nanopowders was examined by the spread plate method using bacterial strains such as Escherichia coli, Sarcina lutea, and Bacillus subtilis. The best antibacterial properties against Sarcina lutea strain were achieved in the amorphous-Al2O3-Ag+ and Al2O3-Ag2O nanopowders, whereas the worst antimicrobial activity against Bacillus subtilis and Escherichia coli was shown by the Al2O3-Ag+ and Al2O3-Ag nanopowders. The observed increase of the antibacterial activity as the silver content was not however significant for Al2O3-Ag nanopowders. The results obtained in the present experiments show that the Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders, possessing good bactericidal properties, can be produced by using consecutive stages of dry sol-gel method, and Al2O3 nanopowder added with Ag2O is considered as the best raw material in the production of antiseptic materials. Agnieszka Maria Jastrzębska, Ewa Karwowska, Andrzej R. Olszyna, and Antoni R. Kunicki Copyright © 2013 Agnieszka Maria Jastrzębska et al. All rights reserved. Synthesis of Silver-Doped Zinc Oxide Nanocomposite by Pulse Mode Ultrasonication and Its Characterization Studies Thu, 12 Sep 2013 09:59:27 +0000 http://www.hindawi.com/journals/jns/2013/785064/ The synthesis of silver-doped zinc oxide (Ag:ZnO) nanocomposite material was achieved using a simple chemical coprecipitation method, in which 0.2 M zinc chloride and 0.001 M silver nitrate coprecipitated with 25% ammonia solution by pulse mode dispersion using ultrasonicator. The obtained silvery white precipitate was dried overnight at 110°C in hot air oven, and the powder was collected. The resulted Ag:ZnO nanocomposite was structurally and optically characterized using various techniques. The X-ray diffraction (XRD) pattern clearly showed the presence of crystalline Ag:ZnO particles. Further, UV-Vis spectrophotometer and fourier transform infrared spectroscopy (FT-IR) results showed the presence of Ag:ZnO nanocomposite at specific wavelengths. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis confirm that the synthesized Ag:ZnO nanocomposite material was truncated nanorod in shape and has 48 to 226 nm size in diameter. T. Siva Vijayakumar, S. Karthikeyeni, S. Vasanth, Arul Ganesh, G. Bupesh, R. Ramesh, M. Manimegalai, and P. Subramanian Copyright © 2013 T. Siva Vijayakumar et al. All rights reserved.