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 Applied Nanoscience   [7 followers]  Follow       Open Access journal    ISSN (Print) 2190-5509 - ISSN (Online) 2190-5517    Published by SpringerOpen  [224 journals]
• Hydrothermal–electrochemical growth of heterogeneous ZnO: Co films

• Abstract: Abstract This study demonstrates the preparation of heterogeneous ZnO: Co nanostructures via hydrothermal–electrochemical deposition at 130 °C and −1.1 V (vs Ag/AgCl (satd)) in dimethyl sulfoxide (DMSO)–H2O mixture. Under the stated conditions, ZnO: Co nanostructures grow preferentially along (002) direction. Strength of directional growth progressively increases with the increasing concentration of Co(II) in the deposition bath. Films are composed of hexagonal Wurtzite ZnO, metallic cobalt, and mixed cobalt oxide on the surface and cobalt(II) oxide in deeper levels. Increasing the Co(II) concentration in the deposition bath results in different morphological features as well as phase separation. Platelets, sponge-like structures, cobalt-rich spheres, microislands of cobalt-rich spheres which are interconnected by ZnO network can be synthesized by adjusting [Co(II)]: [Zn(II)] ratio. Growth mechanisms giving rise to these particular structures, surface morphology, crystal structure, phase purity, chemical binding characteristics, and optical properties of the deposits are discussed in detail.
PubDate: 2017-08-03

materials

• Abstract: Abstract In this study, nano-crystalline lead sulfide (PbS) and lead oxide (PbO) were synthesized using hassle-free and cost-effective chemical route. Lead oxalate (PbC2O4) precursor was thermally decomposed to obtain the nano-crystalline PbO, while PbS nanoparticles were synthesized by microwave irradiation on a mixture of PbC2O4 precursor and sodium thiosulfate. Resulting materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, ultraviolet–visible (UV–Vis) spectrophotometry, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). XRD confirmed the tetragonal structure for PbO and face-centered cubic for PbS with average crystallite sizes varying from 20 to 30 nm for both materials. From UV–Vis spectra, direct band gap energies were calculated to be 2.51 and 2.23 eV for PbO and PbS, respectively. Various decomposition stages during heat treatment of PbO and PbS, as revealed by TGA/DSC, are discussed in detail.
PubDate: 2017-08-02

• High rate capability and cyclic stability of hierarchically porous Tin
oxide (IV)–carbon nanofibers as anode in lithium ion batteries

• Abstract: Abstract Tin oxide–carbon composite porous nanofibres exhibiting superior electrochemical performance as lithium ion battery (LIB) anode have been prepared using electrospinning technique. Surface morphology and structural characterizations of the composite material is carried out by techniques such as XRD, FESEM, HR-TEM, XPS, TGA and Raman spectroscopy. FESEM and TEM studies reveal that nanofibers have a uniform diameter of 150–180 nm and contain highly porous outer wall. The carbon content is limited to ~10% in the nanofibers as shown by the TGA and EDAX which does not fade the high capacity of SnO2. These nanofibers delivered a higher discharge capacity of 722 mAh/g even after 100 cycles at high rate of 1C. The excellent electrochemical performance can be ascribed to the synergy effect of small amount of carbon in the composite and the hierarchically porous structure which accommodate large volume changes associated with Li-ion insertion–desertion. The porous nano-architecture would also provide a short diffusion path for Li+ ions in addition to facilitating high flux of electrolyte percolation through micropores. The electrochemical performance of composite material has also been tested at 60 °C at a higher rate of 2C and 5C. Post cycling FESEM analysis shows no volumetric and morphology changes in porous nanofibers after completing rate capability at high rate of 10C.
PubDate: 2017-07-29

• Development of polyvinyl acetate thin films by electrospinning for sensor
applications

• Abstract: Abstract Electrospinning is an effective process for synthesis of polymer fibers with diameters ranging between nanometers and micrometers by employing electrostatic force developed due to application of high voltage. The present work aims to develop an electrospinning system and optimize the process parameters for synthesis of Polyvinyl Acetate thin films used for gas and humidity sensors. Taguchi’s Design of Experiment was adopted considering three main factors at three different levels for optimization of process parameters. The factors considered were flow rate (0.5, 0.6 and 0.7 ml/h), voltage (18, 19 and 20 kV) and spinneret to collector distance (8, 9, 10 cm) with fiber diameter as the response factor. The main effect plots and interaction plots of the parameters were studied to determine the most influencing parameter. Flow rate was the most significant factor followed by spinneret to collector distance. Least fiber diameter of 24.83 nm was observed at 19 kV, 0.5 ml/h flow rate and 8 cm spinneret to collector distance. SEM images revealed uniform fiber diameter at lower flow rate while bead formation increased monotonically with rise in flow rate.
PubDate: 2017-07-22

• Room temperature CO 2 gas sensors of AuNPs/mesoPSi hybrid structures

• Abstract: Abstract Mesoporous silicon (mesoPSi) layer prepared by a laser-assisted etching process in HF acid has been employed as CO2 gas sensors. The surface morphology of mesoPSi was modified by embedding gold nanoparticles AuNPs by simple and quick dipping process in different gold salts concentrations to form mesoPSi/AuNPs hybrid structures. Morphology of hybrid structures was investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrical characteristics of the prepared gas sensor were carried out at room temperature. It was found that the nanoparticles size, shape and the specific surface area of the nanoparticle strongly influence the current–voltage characteristics. Considerable improvement was noticed in sensitivity, response and recovery times of gas sensor with decreasing incorporated AuNPs into the mesoPSi matrix.
PubDate: 2017-07-17

• Effect of plating temperature on electroless amorphous Ni–P film on Si
wafers in an alkaline bath solution

• Abstract: Abstract Nickel–phosphorus (Ni–P) film was deposited by electroless process on the surface of p-type polycrystalline silicon at the temperature of 60–80 °C and pH value of 10.0. The effect of plating temperature on morphology, crystallographic structure, chemical composition and deposition rate of Ni–P film was studied. Microstructure and morphology of surface and cross section of the film were examined by a scanning electron microscopy and optical microscopy. The crystallographic structure and chemical composition of the film were determined by X-ray diffraction and energy dispersive spectroscopy, respectively. The results show that electroless Ni–P films were composed of the amorphous phase. The stable value P-content of the film was maintained at about 12 wt% with increasing bath temperature. The film surface was dense, and no cracking was found at 60 and 80 °C. However, the film deposited at 70 and 80 °C had a poor adherence to the substrate with evidence of delamination. The deposition rate of the film was increased with increasing plating temperature. At the same time, the deposition mechanism of the film on silicon substrate in the alkaline bath solution was addressed.
PubDate: 2017-07-01

• Application of graphene from exfoliation in kitchen mixer allows
mechanical reinforcement of PVA/graphene film

• Abstract: Abstract Mechanical properties of polyvinyl alcohol (PVA) can be reinforced from the addition of graphene into its matrix. However, pristine graphene lacks solubility in water and thus makes dispersion a challenging task. Notably, functionalisation of graphene is required to accommodate graphene presence in the water. In this work, we have used a kitchen mixer to produce gum Arabic–graphene (GGA) for the first time as filler for mechanical reinforcement of PVA. For the characterisation of exfoliated graphene, mean lateral size of GGA was measured from the imaging by transmission electron microscopy while the mean thickness of graphene was predicted from the obtained spectra by Raman spectroscopy. During the preparation of PVA/graphene film by solution casting, GGA was varied between 0, 0.05, 0.075, 0.10 and 0.15 wt% in concentration. We found that the presence of GGA in PVA improves the tensile stress and elastic modulus about 72–200 and 19–187% from the original values. The data from Halpin–Tsai meanwhile suggested that the mechanical reinforcement of PVA/graphene film is due to the random distribution network of GGA in PVA.
PubDate: 2017-06-26

• Dual mechanism-based sensing of mercury using unmodified,
heteroepitaxially synthesized silver nanoparticles

• Abstract: Abstract Mercury and its compounds are widely distributed in the environment and have a significant negative impact on human health. In this paper, we report the development of a rapid and facile method for the detection of mercury ions (Hg2+) using heteroepitaxially synthesized unmodified silver nanoparticle-based smart probes using UV–Vis spectrophotometer and also through the naked eye by means of a paper-based sensor strip. The silver nanoparticles were prepared by heteroepitaxial growth method using gold seed nanoparticle of ~2.4 nm size as the template. The silver is grown on the seed particles by reducing the silver–ammonia complex using glucose, which resulted in Glu–AgNPs having an average size of 14.65 ± 3.53 nm. The sensing of mercury ions was carried out in aqueous solution and the reaction response was monitored by UV–Vis spectrophotometer. The interaction of Hg2+ with Glu–AgNPs resulted in a significant drop in the absorbance at 402 nm along with a prominent color change (from bright yellow to colorless) and wavelength shift (blue shift). The limit of detection (LOD) of this assay was found to be 100 nM (i.e., 20 ppb) with a good linearity in the concentration range of 100–10 mM. To further ease the detection process and make it field deployable, we attempted to develop a paper-based sensor strip by immobilizing Glu–AgNPs on a paper strip. Upon interaction with mercury solution of varying concentrations, the decoloration of the spots could be observed easily through naked eyes, with the limit of detection under sub-optical conditions being 1 µM.
PubDate: 2017-06-08

• Non-enzymatic detection of glucose in fruits using TiO 2 –Mn 3 O 4
hybrid nano interface

• Abstract: Abstract Consumption of fruits leads to increase in glucose level in blood for diabetic patients, which in turn leads to peripheral, vascular, ocular complications and cardiac diseases. In this context, a non-enzymatic hybrid glucose biosensor was fabricated for the first time to detect glucose by immobilizing titanium oxide–manganese oxide (TiO2–Mn3O4) nanocomposite and chitosan membrane on to the surface of Pt working electrode (Pt/TiO2–Mn3O4/chitosan). TiO2–Mn3O4 nanocomposite catalyzed the oxidation of glucose to gluconolactone in the absence of glucose oxidase enzyme with high electron transfer rate, good biocompatibility and large surface coverage. Electrochemical measurements revealed the excellent sensing response of the developed biosensor towards glucose with a high sensitivity of 7.073 µA mM−1, linearity of 0.01–0.1 mM, low detection limit of 0.01 µM, reproducibility of 1.5% and stability of 98.8%. The electrochemical parameters estimated from the anodic process were subjected to linear regression models for the detection of unknown concentration of glucose in different fruit samples.
PubDate: 2017-06-03

• A lucrative chemical processing of bamboo leaf biomass to synthesize
biocompatible amorphous silica nanoparticles of biomedical importance

• Abstract: Abstract Synthesis of silica nanoparticles from natural resources/waste via cost effective route is presently one of the anticipating strategies for extensive applications. This study reports the low-cost indigenous production of silica nanoparticles from the leftover of bamboo (leaf biomass) through thermal combustion and alkaline extraction, and examination of physico-chemical properties and yield percentage using comprehensive characterization tools. The outcome of primed silica powder exhibits amorphous particles (average size: 25 nm) with high surface area (428 m2 g−1) and spherical morphology. Despite the yield percentage of silica nanoparticles from bamboo leave ash is 50.2%, which is less than rice husk ask resources (62.1%), the bamboo waste is only an inexpensive resource yielding high purity (99%). Synthesis of silica nanoparticles from natural resources/waste with the help of lucrative route is at present times one of the anticipating strategies for extensive applications. In vitro study on animal cell lines (MG-63) shows non-toxic nature of silica nanoparticles up to 125 µg mL−1. Hence, this study highlights the feasibility for the mass production of silica nanoparticles from bamboo leave waste rather using chemical precursor of silica for drug delivery and other medical applications.
PubDate: 2017-06-01

• A study of the optical band gap of zinc phthalocyanine nanoparticles using
UV–Vis spectroscopy and DFT function

• Abstract: Abstract In the present work, we used the ultraviolet–Visible (UV–Vis) spectroscopy technique to find the optical band gap of zinc phthalocyanine nanoparticles (ZnPc-NP) experimentally. Moreover, we used a time-dependent density functional theory (TDDFT) to simulate the UV–Vis absorption spectrum of ZnPc molecule in gas and solution phases. The ZnPc-NP absorption spectrum shows a shift toward higher energies compared to the bulk ZnPc. The simulated UV–Vis and the experimental nanoparticle’s spectrum were found to have a good agreement. The ZnPc energy band gap from the DFT calculations shows how it’s possible to get wider range of energy band gap for the ZnPc. The ZnPc-NP’s size and shape were examined using the transmission electron microscope (TEM).
PubDate: 2017-04-27

• Photocatalytic degradation of methyl orange dye by pristine titanium
dioxide, zinc oxide, and graphene oxide nanostructures and their

• Abstract: Abstract Discharge of azo dyes by textile and allied industries to the environment is a growing problem. Degradation of an azo dye, methyl orange (MO), was tested in simulated wastewater with different oxide nanomaterials acting as photocatalysts under visible light. Titanium dioxide (TiO2), zinc oxide (ZnO), and graphene oxide (GO) were synthesized, characterized, and applied for adsorptive and photocatalytic removal of the dye. Factors such as initial concentration of MO and size of nanoparticle photocatalyst were varied to determine the optimum conditions for dye removal. Finally, nanocomposites of the three materials (GO–TiO2–ZnO) were synthesized and tested for its photocatalytic performance. The composition of the individual oxide in the nanocomposite was then varied to achieve the best photocatalytic performance.
PubDate: 2017-04-22

• Effect of Mg doping and sintering temperature on structural and
morphological properties of samarium-doped ceria for IT-SOFC electrolyte

• Abstract: Abstract Samples of Sm and Mg co-doped ceria electrolyte of Ce1−x Sm x−y Mg y O2−δ (x = 0.2; y = 0.00, 0.05, 0.1, 0.15, and 0.175) were synthesized by sol–gel process. The prepared samples were sintered at 1100 and 1400 °C for 4 h. The bulk densities were measured by Archimedes method. XRD measurements indicate that the synthesized samples were in single-phase cubic fluorite structure (space group Fm3m). The cell parameters decrease with the concentration of Mg, and 2θ values slightly shift towards right. The particle sizes obtained were between 7.14 and 17.44 nm. The sintered sample achieved 95% of theoretical density. FTIR spectra of samples sintered at 1400 °C indicates weak interactions between 3550–3400 cm−1 and 1600–1300 cm−1 are attributed to O–H stretching modes and strong bonds 850–450 cm−1 are assigned to characteristic Ce–O vibrations. The surface morphology and chemical composition were analyzed by SEM and EDS, SEM micrographs show spherical faceted grains, and the samples were crack free, dense material with some pores on surface which are inconsistent with density results. The average grain size obtained was 0.5 μm. Particle size obtained by TEM was in agreement with that obtained by XRD. The high-density ceria co-doped ceramic can be used as electrolyte in SOFC.
PubDate: 2017-04-21

• Synthesis and magnetic induction heating properties of Gd-substituted
Mg–Zn ferrite nanoparticles

• Abstract: Abstract Gadolinium-substituted magnesium–zinc ferrite (Mg x Zn1−x Gd y Fe2−y O4) nanoparticles with different metal compositions for x between 0 and 1 and y between 0 and 0.06 were synthesized via coprecipitation of metal hydroxides, followed by calcination. Their crystal structure was characterized via X-ray diffraction analysis, confirming that the Gd-substituted Mg–Zn ferrite samples had a single-phase spinel structure. The metal composition significantly affected the crystal structure, including the lattice parameters and crystallite size. Scanning electron microscopy (SEM) showed that the ferrite samples had a diameter of approximately 50–200 nm. Furthermore, the temperature rise in an alternating magnetic field was measured, and the magnetic induction heating properties were evaluated using the specific absorption rate (SAR) determined from the temperature profile. The SAR significantly varied depending on the compositions of x and y. When x = 0.5 and y = 0.02, the SAR was found to be at maximum. This reveals that the compositions can control the magnetic induction heating properties. The results suggest that Gd-substituted Mg–Zn ferrite nanoparticles are promising candidates for magnetic hyperthermia applications.
PubDate: 2017-04-19

• A molecular dynamics investigation into the adsorption behavior inside
{001} kaolinite and {1014} calcite nano-scale channels: the case with
confined hydrocarbon liquid, acid gases, and water

• Abstract: Abstract A set of molecular dynamics simulations was conducted, as the first comparative study of the adsorption behavior of liquid hydrocarbon/acid gases/water molecules over $$\{ 10\bar{1}4\}$$ calcite surface and {001} octahedral kaolinite surface in nano-confined slit. According to atomic z-density profiles, hydrocarbon molecules have higher tendency towards the $$\{ 10\bar{1}4\}$$ calcite surface than the {001} octahedral kaolinite surface. In addition, water molecules form stronger adsorption layer over calcite surface than kaolinite. In contrast, acid gas molecules have higher tendency towards kaolinite surface than calcite. This behavior was spotted within nanometer-sized slit pores. The results also point to reduction in self-diffusion coefficient of molecules with strong adsorption over mineral surfaces in nano-confined environment.
PubDate: 2017-04-12

• Sonication-assisted synthesis of polystyrene (PS)/organoclay
nanocomposites: influence of clay content

• Abstract: Abstract This article presents the synthesis of a series of polystyrene (PS)/organoclay nanocomposite films consisting of different contents of clay (1–7 wt%) by sonication-coupled solvent-blending technique. The prepared PS nanocomposite films were characterized using various techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). The XRD and TEM results revealed the formation of exfoliated nanocomposites at lower loading of organoclay (<5 wt%). The presence of various functional groups in the organoclay and PS/organoclay nanocomposite was verified by FTIR spectra. The thermal stability of PS nanocomposites was significantly improved as compared to pristine PS, which is evident from TGA analysis. When 10% mass loss was chosen as a point of reference, the thermal degradation temperature of PS nanocomposite holding 7 wt% of organoclay was found to be 30 °C more over pristine PS. The thermal kinetic parameters such as activation energy (E a), pre-exponential factor (A), and the order of reaction (n) were determined by employing the Coats–Redfern model. Thermal degradation reaction mechanism of PS nanocomposites was also investigated.
PubDate: 2017-04-11

• Optimized interaction parameters for metal-doped endohedral fullerene

• Abstract: Abstract Interaction between various atoms doped inside C60 can be modeled using interaction potentials and, thus, cohesive energy and other physical constants may be calculated. In case of metal-doped fullerene total energy may be written in terms of three different types of interactions, namely carbon–carbon interaction, metal–metal interaction and carbon–metal interaction. Brenner potential, Gupta potential, and Lennard–Jones potentials have been used to model these interactions respectively. Generally, parameters used in these model potentials are not readily available and need to be fine-tuned for different dopants. In this paper, we have deduced/optimized these interaction parameters for Cu, Ag, Al and Ga doped C60 comparing with our Density Functional Theory (DFT) results and hence predicting the stability of various metal-doped fullerenes. Total energy calculations reveal that a maximum of nine copper atoms can be doped inside the fullerene cage and form stable complex without distorting the cage significantly. As we add more number of Cu atoms in the fullerene molecule, cage structure breaks down. In the same way, we have done calculations for Ag, Al and Ga atoms doped inside the fullerene molecule and found that the maximum of eight, nine, nine atoms can form stable complexes.
PubDate: 2017-04-10

• ZnO nanoparticles (ZnO-NPs) and their antifungal activity against coffee
fungus Erythricium salmonicolor

• Abstract: Abstract In this work, a methodology of synthesis was designed to obtain ZnO nanoparticles (ZnO NPs) in a controlled and reproducible manner. The nanoparticles obtained were characterized using infrared spectroscopy, X-ray diffraction, and transmission electron microscopy (TEM). Also, we determined the antifungal capacity in vitro of zinc oxide nanoparticles synthesized, examining their action on Erythricium salmonicolor fungy causal of pink disease. To determine the effect of the quantity of zinc precursor used during ZnO NPs synthesis on the antifungal capacity, 0.1 and 0.15 M concentrations of zinc acetate were examined. To study the inactivation of the mycelial growth of the fungus, different concentrations of ZnO NPs of the two types of synthesized samples were used. The inhibitory effect on the growth of the fungus was determined by measuring the growth area as a function of time. The morphological change was observed with high-resolution optical microscopy (HROM), while TEM was used to observe changes in its ultrastructure. The results showed that a concentration of 9 mmol L−1 for the sample obtained from the 0.15 M and at 12 mmol L−1 for the 0.1 M system significantly inhibited growth of E. salmonicolor. In the HROM images a deformation was observed in the growth pattern: notable thinning of the fibers of the hyphae and a clumping tendency. The TEM images showed a liquefaction of the cytoplasmic content, making it less electron-dense, with the presence of a number of vacuoles and significant detachment of the cell wall.
PubDate: 2017-04-09

• Enhance the figure of merit for flexible thermoelectric materials by
reducing the screening effect

• Abstract: Abstract A flexible thermoelectric materials (FTEM) films based on Polydimethylsiloxane as the polymer matrix and (Zinc Oxide, Polyaniline and multi wall Carbon nanotube) as the fillers were prepared. The fillers were prepared using modified sol–gel method to enhance the distribution of the nanoparticles inside the polymer matrix and good performance. The Seebeck coefficient, electrical conductivity, thermal conductivity and dielectric measurements were carried out for all of the four films. The Seebeck coefficient results for the investigated films were −40, 220, −120, 280 μv/k° at 200 °C for FTEM 1, 2, 3, 4 alternatively. The sign and the value for the Seebeck measurements show a great dependent on the filler type add to the film. The electrical conductivity results for the films was varied from 2 × 10−8 to 0.14 S/m and strongly dependent on the fillers electrical conductivity. The less dependent on the thermal conductivity of the fillers and a slight change in the thermal conductivity value of the films were obtained. The figure of merit for the films was ranged from 1.14 × 10−16 to 3.134 × 10−8. The dielectric results ranged from 4 to 3500. Reducing the screening effect will increase the electrical conductivity and Seebeck coefficient values.
PubDate: 2017-04-07

• Assessment of toxicity in fresh water fish Labeo rohita treated with
silver nanoparticles

• Abstract: Abstract Silver nanoparticles (17.78 ± 12.12 nm) were synthesized by the reduction of 0.5 M silver nitrate using formaldehyde as reducing and triethylamine as promoting and stabilizing agent. The particles were grain like agglomerates with spherical, centered-face cubic and crystalline in nature. The sample was highly pure with amine (NH) as associated and capping molecules. Further, the genotoxicity and oxidative stress of these particles were evaluated using Labeo rohita (L. rohita) as genetic model exposed (10–55 mg L−1 dose) through aquatic medium for 28 days. The cells were produced with micronuclei, fragmented, lobed and buds nuclei in dose dependent manner. The highest incidence of comet was recoded (27.34 ± 5.68) at 55 mg L−1 Ag-NPs and 14 days treatment. Then frequency was decreased to 22.65 ± 6.66% after 28 days due to complex repair mechanism. Moreover, the treatment also produces the oxidative stress and disturbs the level of GST in gill and liver tissue. There was a sharp decline in the activities of GST and this decrease of activity increase the MDA content. Further, the elevated level of GSH represents that the liver has started defensive mechanism against oxyraidcals. This study concluded, Ag-NPs are genotoxic in nature and produce micronuclei, comet cells and also induces oxidative stress in aquatic organisms.
PubDate: 2017-04-05

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Heriot-Watt University
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