Synthesis,characterization, and electrochemical properties of poly(ethylene oxide)-based polyaniline electrolyte complex

The polymer electrolyte based poly(ethylene oxide) complexed with conducting polyaniline (PANI) has been prepared in different weight percentages. The complexation is confirmed by Fourier transform infrared spectroscopy (FTIR).The change in morphology is studied by using scanning electron microscopy. The DC conductivity measurements are carried out using Keithley digital multimeter. It is seen that DC conductivity shows exponential behavior for all PEO : PANI complexes. It is observed that among all the PEO : PANI complexes, 50 wt % of PEO in PANI shows highest conductivity. Electrochemical cell parameters for battery applications at room temperature also have been determined. The samples are fabricated for battery application in the configuration of Na:(PEO : PANI):(I₂ + C + sample), and their experimental data are measured using Wagner polarization technique. The cell parameters results in an open-circuit voltage of 0.4 V and a short-circuit current of 902 μA for PEO : PANI (50 : 50) composite. Hence, these composites can be better candidates for the polymer electrolyte studies. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Dielectric relaxation in complex perovskite Ba(Bi1/2Ta1/2)O3

A new lead-free perovskite Ba(Bi_1/2Ta_1/2)O₃ was prepared by conventional ceramic fabrication technique at 1,200 °C/4 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were determined from the experimental results using FullProf software. The crystallite size and lattice strain were estimated from Williamson-Hall approach. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space group Pm3m. EDAX and SEM studies were carried out in order to evaluate the quality and purity of the compound. Permittivity data showed a low temperature coefficient of capacitance (T _CC  < 4%) up to +125 °C. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. Electric modulus studies supported the hopping type of conduction in Ba(Bi_1/2Ta_1/2)O₃.     

Compaction and Sintering Behavior of Niobium Powder for Making Consumable Electrodes

Niobium consumable electrodes of 10?mm dia?×?50?mm length were prepared by cold isostaic pressing with compaction pressure of 125?C250?MPa. The compacts were sintered under vacuum at different temperatures in the range of 1000?C1800?oC. The CIPed and sintered electrodes were characterized with respect to chemical analysis, density, microstructure and bend strength. The results showed that there is a marginal improvement in density at a sintering temperature in the range of 1000?C1400?oC, while a significant improvement in density was observed at sintering temperature in the range of 1600?C1800?oC. The bend strength of sintered electrode was found to increase with increasing sintering temperature and that attains a highest value at a sintering temperature in the range of 1600?C1800?oC. Sintering at a temperature higher than 1400?oC leads to decrease in oxygen content of the electrodes. The oxygen content was decreased from 2000 to 500?ppm when electrode was sintered at 1800?oC.     

利用基于扫描相机的荧光寿命成像显微技术研究细胞周期

利用基于扫描相机的荧光寿命成像显微系统,以细胞周期为模型,研究转染绿色荧光蛋白的HeLa细胞的荧光寿命。结果表明,处于周期内不同进程的细胞的荧光寿命为2.50~3.00 ns。处于分裂期的细胞的荧光寿命在1 h内从2.86 ns下降到2.82 ns;在DNA合成前期的8 h内,荧光寿命从2.82 ns下降到2.78 ns。荧光寿命的差异反映了细胞周期中核浆内大分子浓度的变化,对了解细胞周期的分子机制有一定的意义。     

Transceiver Design and Performance Analysis of Space Time Coded Fractal Modulation

The filterbank transceiver structure for fractal modulation has been developed. It has been shown that the transceiver complexity is comparable to that of OFDM.The use of orthogonal space time block codes (OSTBC) in conjunction with Fractal Modulation (STFrM) in the presence of frequency selective fading channels has also been considered. An L scale fractal modulation and coherent demodulation effectively converts a frequency selective channel into L flat fading channels per information symbol with random scale gains. The analysis of the proposed scheme in terms of bit error rate has been performed. A diversity order of m _T m _R L can be achieved, where m _T ,m _R are the number of transmitters and receivers, respectively. This increase in diversity order in comparison with that achieved for the OFDM case is at a cost of lower spectral efficiency. However the spectral efficiency of STFrM can be improved R times by the use of multiplicity ‘R’ multiwavelets.     

ZSM-5 Supported Cobalt Catalyst for the Direct Production of Gasoline Range Hydrocarbons by Fischer–Tropsch Synthesis

Abstract  

Fischer–Tropsch synthesis (FTS) reaction for the direct production of gasoline range hydrocarbons (C₅–C₉) from syngas was investigated on cobalt-based FTS catalyst supported on the ZSM-5 possessing a four different Si/Al ratio. The FTS catalysts were prepared by impregnation method using cobalt nitrate precursor in a slurry of ZSM-5, and they were characterized by surface area, XRD, H₂-TPR and NH₃-TPD. Cobalt supported catalyst on ZSM-5 having a low Si/Al ratio of 15 was found to be superior to the other catalysts in terms of better C₅–C₉ selectivity due to the formation of small cobalt particle and the presence of larger number of weak acidic sites. It also exhibited the highest catalytic activity because of the higher reducibility and the small cobalt particle size.     

Sliding wear response of a grey cast iron: Effects of some experimental parameters

This investigation pertains to the influence of some test parameters like applied load, sliding speed and test environment on the sliding wear behaviour of a grey cast iron. Properties studied were wear rate, frictional heating and friction coefficient in dry and oil lubricated conditions. The wear response of the samples has been discussed in terms of specific characteristics like load bearing, lubricating and cracking tendency of different microconstituents of the cast iron. Examination of wear surfaces, subsurface regions and debris particles has also been carried out to understand the operating wear mechanisms and further substantiate the observed response of the samples.     

Preparation and characterization of 4A zeolite‐filled mixed matrix membranes for pervaporation dehydration of isopropyl alcohol

Sodium carboxymethylcellulose/poly (vinyl alcohol) mixed matrix membranes filled with different amounts 4A zeolite (0, 5, 10, 15, and 20 wt %) were prepared by solution casting method. Prepared membranes were crosslinked with GA and used for pervaporation dehydration of isopropyl alcohol of different feed mixtures at 35°C. On increment in zeolite content in the membrane it was found the improvement in the performance of the membrane, due to its hydrophilic nature and molecular sieving effect in addition to its favorable interaction with hydrophilic sodium carboxymethylcellulose and polyvinyl alcohol. The structure and chemical constituents of the MMM's were investigated by attenuated total reflectance Fourier transform infrared spectroscopy. Thermal stability of the membranes was assessed by DSC and TGA techniques. Crystallinity of the membranes was assessed using X‐ray diffraction, and the morphological properties were assessed by scanning electron microscopy. Mechanical properties were also carried out to determine the tensile strength and % of elongation at break using universal testing machine. It was found that the mechanical strength increases with increase in the zeolite content upto 15 wt % of zeolite with an optimum tensile strength of 113.31 N/mm². Pervaporation was carried out to asses the membrane performance, the highest flux and selectivity obtained is 0.584 kg/m²/h and 6945 for NaCMCA20 and NaCMCA15, respectively, for a feed composition containing 17.5 and 10 wt % of water in the feed and further swelling studies also supporting the pervaporation results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Pervaporation separation of IPA‐water mixtures through 4A zeolite‐filled sodium alginate membranes

Incorporation of zeolites into natural polymers has been shown experimentally to enhance both the flux and selectivity in pervaporative dehydration separation of organic compounds. Pervaporation is a promising membrane technique for separation of volatile organic compounds (VOCs)/water mixtures. In this study, hydrophilic sodium alginate (SA) mixed membranes were prepared using solution casting technique by incorporating zeolites into the polymer matrix. The prepared membranes were characterized by ATR‐Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Thermal Gravimetric Analysis (TGA), and differential scanning calorimetry (DSC) were tested in a laboratory scale pervaporation experimental set‐up. The effect of experimental parameters such as the type and composition of zeolites on permeation flux and selectivity was investigated. When tested on IPA‐water mixtures, the zeolite‐filled membrane was found to give much higher selectivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011