3D nanoporous nanowire current collectors for thin film microbatteries

Conventional thin film batteries are fabricated based on planar current collector designs where the high contact resistance between the current collector and electrodes impedes overall battery performance. Hence, current collectors based on 3D architectures and nanoscale roughness has been proposed to dramatically increase the electrode-current collector surface contact areas and hence significantly reduce interfacial resistance. The nanorod-based current collector configuration is one of several 3D designs which has shown high potential for the development of high energy and high power microbatteries in this regard. Herein we fabricate a nanoporous nanorod based current collector, which provides increased surface area for electrode deposition arising from the porosity of each nanorods, yet keeping an ordered spacing between nanorods for the deposition of subsequent electrolyte and electrode layers. The new nanostructured 3D current collector is demonstrated with a polyaniline (PANI)-based electrode system and is shown to deliver improved rate capability characteristics compared to planar configurations. We have been able to achieve stable capacities of ~32 μAh/cm(2) up to 75 cycles of charge/discharge even at a current rate of ~0.04 mA/cm(2) and have observed good rate capability even at high current rates of ~0.8 mA/cm(2).     

Exergetic analysis of a vapour compression refrigeration system with R134a, R143a, R152a, R404A, R407C, R410A, R502 and R507A

This communication deals with the exergetic analysis of a vapour compression refrigeration system with selected refrigerants. The various parameters computed are COP and exergetic efficiency in the system. Effects of degree of condenser temperature, evaporator temperature and sub-cooling of condenser outlet, supper-heating of evaporator out let and effectiveness of vapour liquid heat exchanger are also computed and discussed. In this study, it was found that R134a has the better performance in all respect, whereas R407C refrigerant has poor performance.     

Superior copper promoted bimetallic catalysts for chemoselective hydrogenation of ortho-chloro-nitrobenzene

In the present study, highly dispersed copper promoted bimetallic nanocomposite oxides with superior catalytic performance for vapor phase chemoselective hydrogenation of ortho-chloro-nitrobenzene were successfully prepared by deposition–precipitation and impregnation methods and characterized using different techniques. XRD and TPR results revealed the presence of small and extremely well dispersed metal oxide particles over the high surface area ceria–silica support. TEM analysis confirmed existence of nanocrystals with an average particle size of 7 nm. Among different catalysts employed, CuO–NiO/CS exhibited high conversion (96.6%), high product selectivity (98%), and excellent stability.     

Correlation Between Charge, Spin and Lattice in La–Eu–Sr Manganites

To understand the structural, electrical, magnetic, elastic and anelastic properties of La_0.67?x Eu _x Sr_0.33MnO₃ (0.30≤x≤0.39) manganites, a series of samples was prepared by citrate gel route. X-ray diffraction studies along with Rietveld analysis indicate the samples crystallize in single phase with Pnma space group. Studies on the variations of magnetization with temperature indicate that the Curie transition temperature (T _C) decreases with increasing Eu content. Furthermore, Eu substitution is found to increase the electrical resistivity and significantly enhances the colossal magnetoresistance effect, while it is found to decrease the characteristic metal–insulator transition temperature (T _P). On analyzing the electrical resistivity data, it has been concluded that the resistivity below T _P can be explained based on electron–electron, electron–phonon and two magnon scattering processes, while that above T _P, the adiabatic small polaron model is found to explain the observed behavior. Finally, the longitudinal modulus (L) and internal friction (Q ^?1) have been measured and a dramatic change in L (T) is observed at T _C, accompanied by a sharp peak in Q ^?1 (T). Simultaneous occurrence of magnetic, transport and lattice anomalous behavior at T _C indicate the presence of strong electron–phonon and spin–phonon interactions in these manganites.     

The structural influence of aluminium ions on emission characteristics of Sm3+ ions in lead aluminium silicate glass system

Optical absorption and photoluminescence characteristics of Sm³⁺ ions in lead silicate glasses mixed with different concentrations of Al₂O₃ (5–10 mol%) have been investigated. From these studies, the radiative properties viz., spontaneous emission probability A, the total emission probability, the radiative lifetime τ_R, the fluorescent branching ratio β of emission transition of ⁴G_5/2 → ⁶H_7/2 along with other transitions for Sm³⁺ have been evaluated and found to be the highest for the glass mixed with 8.0 mol% of Al₂O₃.The IR spectral studies have indicated that Al³⁺ ions do participate in the glass network with AlO₄ and AlO₆ structural units and further revealed that the concentration of octahedral aluminium ions induce bonding defects in the glass network. Such bonding defects are assumed to be responsible for low phonon losses in these glasses and lead to higher values of radiative parameters for the glass mixed with 8.0 mol% of Al₂O₃.     

Effect of annealing temperature on electrical properties of Au/polyvinyl alcohol/n-InP Schottky barrier structure

In the present work, thin film of polyvinyl alcohol (PVA) is fabricated on n-type InP substrate as an interfacial layer for electronic modification of Au/n-InP Schottky contact. The electrical characteristics of Au/PVA/n-InP Schottky diode are determined at annealing temperature in the range of 100-300 °C by current-voltage (I-V) and capacitance-voltage (C-V) methods. The Schottky barrier height and ideality factor (n) values of the as-deposited Au/PVA/n-InP diode are obtained at room temperature as 0.66 eV (I-V), 0.82 eV (C-V) and 1.32, respectively. Upon annealing at 200 °C in nitrogen atmosphere for 1 min, the barrier height value increases to 0.81 eV (I-V), 0.99 eV (C-V) and ideality factor decreases to 1.18. When the contact is annealed at 300 °C, the barrier height value decreases to 0.77 eV (I-V), 0.96 eV (C-V) and ideality factor increases to 1.22. It is observed that the interfacial layer of PVA increases the barrier height by the influence of the space charge region of the Au/n-InP Schottky junction. The discrepancy between Schottky barrier heights calculated from I-V and C-V measurements is also explained. Further, Cheung's functions are used to extract the series resistance of Au/PVA/n-InP Schottky diode. The interface state density as determined by Terman's method is found to be 1.04 × 10¹² and 0.59 × 10¹² cm^− 2 eV^− 1 for the as-deposited and 200 °C annealed Au/PVA/n-InP Schottky diodes. Finally, it is seen that the Schottky diode parameters changed with increase in the annealing temperature.     

Detection of central nervous system tissue on meat and carcass-splitting band saw blade surfaces using modified fluorescent glial fibrillary acidic protein enzyme-linked immunosorbent assay sampling and extraction procedures

This study was conducted to determine optimal buffer pH, extraction procedure, and temperature for detecting central nervous system (CNS) tissue on meat surfaces and on carcass-splitting band saw blades using swab sampling. Glial fibrillary acidic protein (GFAP) is restricted to CNS tissue and has been used as a marker for CNS tissue presence in meat products. Sample preparation, extraction procedure, and extraction temperature of glial fibrillary acidic protein fluorescent enzyme-linked immunosorbent assay (GFAP F-ELISA) were modified to detect CNS tissue on meat surfaces and on carcass-splitting band saw blades. Maximum GFAP recovery was observed with an extraction buffer pH of 7.4. Extracting samples at room temperature by vortexing for 30 s in 1 ml of extraction buffer (phosphate-buffered saline [pH 7.4] plus 0.05% sodium dodecyl sulfate) consistently provided detection of GFAP on meat surfaces contaminated with 500 microg of spinal cord suspension per 50 cm2 and on carcass-splitting band saw blades contaminated with 20 microg of spinal cord suspension per 50 cm2. Recovery of GFAP was not affected by storing samples overnight at 4 degrees C. The current studies demonstrate the effectiveness of modified sampling procedures and preparations, sample extraction buffer pH, and extraction temperatures. These modifications introduced to the original F-ELISA sampling protocol result in asensitive and repeatable assay for detection of CNS tissue on meat surfaces and on carcass-splitting band saw blades.     

Photovoltaic properties of SnS based solar cells

Polycrystalline thin films of tin sulphide have been synthesised using spray pyrolysis. The layers grown at a temperature of 350 °C had the orthorhombic crystal structure with a strong (1 1 1) preferred orientation. The films had resistivities 30 Ω cm with an optical energy band gap (E_g) of 1.32 eV. Heterojunction solar cells were fabricated using sprayed SnS as the absorber layer and indium doped cadmium sulphide as the window layer and the devices were characterised to evaluate the junction properties as well as the solar cell performance. The current transport across the junction has been modelled as a combination of tunnelling and recombination. The best devices had solar conversion efficiencies of 1.3% with a quantum efficiency of 70%.