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111.
S. Meenakshi S. D. Bhat A. K. Sahu S. Alwin P. Sridhar S. Pitchumani 《Journal of Solid State Electrochemistry》2012,16(4):1709-1721
Hybrid dual-network membranes comprising chitosan (CS)–polyvinyl alcohol (PVA) networks crosslinked with sulfosuccinic acid
(SSA) and glutaraldehyde (GA) and modified with stabilized silicotungstic acid (SWA) are reported for their application in
direct methanol fuel cells (DMFCs). Physico-chemical properties of these membranes are evaluated using thermo-gravimetric
analysis and scanning electron microscopy in conjunction with their mechanical properties. Based on water sorption and proton
conductivity measurements for the membranes, the optimum content of 10 wt.% SWA in the membrane is established. The methanol
crossover for these membranes are studied by measuring the mass balance of methanol using density meter and are found to be
lower compared to Nafion-117 membrane. The membrane–electrode assembly with 10 wt.% stabilized SWA–CS–PVA hybrid membrane
with SSA and GA as crosslinking agent delivers a peak power density of 156 mW cm−2 at a load current density of 400 mA cm−2 and 88 mW cm−2 at a load current density of 300 mA cm−2, respectively, in DMFC at 70 °C. 相似文献
112.
P. Sivakumar S. Meenakshi R. V. Subba Rao 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):603-608
A new process for the partitioning of plutonium and uranium during the reprocessing of spent fuel discharged from fast reactor
was optimised using hydroxyurea (HU) as a reductant. Stoichiometric ratio of HU required for the reduction of Pu(IV) was studied.
The effect of concentration of uranium, plutonium and acidity on the distribution ratio (Kd) of Pu in the presence of HU was
studied. The effect of HU in further purification of Pu such as solvent extraction and precipitation of plutonium as oxalate
was also studied. The results of the study indicate that Pu and U can be separated from each other using HU as reductant. 相似文献
113.
P. Sivakumar S. Meenakshi R. V. Subba Rao 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):763-767
Spent fuel discharged from Fast Breeder Test Reactor (FBTR) in Kalpakkam is being reprocessed by modified plutonium uranium
reduction extraction (PUREX) process using 30% TBP (tributylphosphate) as extractant in the presence of heavy normal paraffin
(HNP) as diluent. Partitioning of uranium (U) and plutonium (Pu) is carried out using oxalate precipitation method. Uranium
oxide product obtained by this method contains appreciable amount of plutonium which has to be recovered. Recovery of plutonium
from this uranium oxide product is carried out by reducing Pu to inextractable Pu(III) using hydroxyurea (HU) and then uranium
is extracted into 30% TBP. A small amount of Pu which is extracted in the organic phase is stripped back to aqueous phase
by scrubbing with scrubbing agent containing 0.1 M HU in 4 M nitric acid. Similarly U and Pu are co-extracted into 30% TBP
and then Pu is removed by scrubbing with 0.1 M HU in 4 M nitric acid. Further decontamination from Pu is obtained in the stripping
stages. By this method Pu contamination in the uranium oxide is brought from 7300 ppm to 0.4–3 ppm (wt/wt). This uranium product
obtained can be handled on table top. 相似文献
114.
This paper considers finite friction contact problems involving an elastic pin and an infinite elastic plate with a circular hole. Using a suitable class of Green's functions, the singular integral equations governing a very general class of conforming contact problems are formulated. In particular, remote plate stresses, pin loads, moments and distributed loading of the pin by conservative body forces are considered. Numerical solutions are presented for different partial slip load cases. In monotonic loading, the dependence of the tractions on the coefficient of friction is strongest when the contact is highly conforming. For less conforming contacts, the tractions are insensitive to an increase in the value of the friction coefficient above a certain threshold. The contact size and peak pressure in monotonic loading are only weakly dependent on the pin load distribution, with center loads leading to slightly higher peak pressure and lower peak shear than distributed loads. In contrast to half-plane cylinder fretting contacts, fretting behavior is quite different depending on whether or not the pin is allowed to rotate freely. If pin rotation is disallowed, the fretting tractions resemble half-plane fretting tractions in the weakly conforming regime but the contact resists sliding in the strongly conforming regime. If pin rotation is allowed, the shear traction behavior resembles planar rolling contacts in that one slip zone is dominant and the peak shear occurs at its edge. In this case, the effects of material dissimilarity in the strongly conforming regime are only secondary and the contact never goes into sliding. Fretting tractions in the forward and reversed load states show shape asymmetry, which persists with continued load cycling. Finally, the governing integro-differential equation for full sliding is derived; in the limiting case of no friction, the same equation governs contacts with center loading and uniform body force loading, resulting in identical pressures when their resultants are equal. 相似文献
115.
Nagarajan Shobana Pandurangan Prakash Antony V. Samrot P. J. Jane Cypriyana Purohit Kajal Mahendran Sathiyasree Subramanian Saigeetha T. Stalin Dhas D. Alex Anand Gokul Shankar Sabesan Bala Sundaram Muthuvenkatachalam Basanta Kumar Mohanty Sridevi Visvanathan 《Molecules (Basel, Switzerland)》2022,27(12)
Plant gums are bio-organic substances that are derived from the barks of trees. They are biodegradable and non-adverse complex polysaccharides that have been gaining usage in recent years due to a number of advantages they contribute to various applications. In this study, gum was collected from Moringa oleifera and Azadirachta indica trees, then dried and powdered. Characterizations of gum polysaccharides were performed using TLC, GC-MS, NMR, etc., and sugar molecules such as glucose and xylose were found to be present. Effects of the gums on Abelmoschus esculentus growth were observed through root growth, shoot growth, and biomass content. The exposure of the seeds to the plant gums led to bio stimulation in the growth of the plants. Poor quality soil was exposed to the gum polysaccharide, where the polysaccharide was found to improve soil quality, which was observed through soil analysis and SEM analysis of soil porosity and structure. Furthermore, the plant gums were also found to have bio-pesticidal activity against mealybugs, which showed certain interstitial damage evident through histopathological analysis. 相似文献
116.
Subhajit Laha Nimish Dwarkanath Abhishek Sharma Darsi Rambabu Sundaram Balasubramanian Tapas Kumar Maji 《Chemical science》2022,13(24):7172
Light hydrocarbon separation is considered one of the most industrially challenging and desired chemical separation processes and is highly essential in polymer and chemical industries. Among them, separating ethylene (C2H4) from C2 hydrocarbon mixtures such as ethane (C2H6), acetylene (C2H2), and other natural gas elements (CO2, CH4) is of paramount importance and poses significant difficulty. We demonstrate such separations using an Al-MOF synthesised earlier as a non-porous material, but herein endowed with hierarchical porosity created under microwave conditions in an equimolar water/ethanol solution. The material possessing a large surface area (793 m2 g−1) exhibits an excellent uptake capacity for major industrial hydrocarbons in the order of C2H2 > C2H6 > CO2 > C2H4 > CH4 under ambient conditions. It shows an outstanding dynamic breakthrough separation of ethylene (C2H4) not only for a binary mixture (C2H6/C2H4) but also for a quaternary combination (C2H4/C2H6/C2H2/CO2 and C2H4/C2H6/C2H2/CH4) of varying concentrations. The detailed separation/purification mechanism was unveiled by gas adsorption isotherms, mixed-gas adsorption calculations, selectivity estimations, advanced computer simulations such as density functional theory (DFT), grand canonical Monte Carlo (GCMC) and ab initio molecular dynamics (AIMD), and stepwise multicomponent dynamic breakthrough experiments.Industrially important C2H4 purification from multi-component hydrocarbon mixtures. 相似文献
117.
Microexplosions in tellurite glasses 总被引:2,自引:0,他引:2
S.K. Sundaram C.B. Schaffer E. Mazur 《Applied Physics A: Materials Science & Processing》2003,76(3):379-384
Femtosecond laser pulses were used to produce localized damage in the bulk and near the surface of baseline, Al2O3-doped and La2O3-doped sodium tellurite glasses. Single or multiple laser pulses were non-linearly absorbed in the focal volume by the glass,
leading to permanent changes in the material in the focal volume. These changes were caused by an explosive expansion of the
ionized material in the focal volume into the surrounding material, i.e. a microexplosion. The writing of simple structures
(periodic array of voxels, as well as lines) was demonstrated. The regions of microexplosion and writing were subsequently
characterized using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and atomic force microscopy (AFM).
Fingerprints of microexplosions (concentric lines within the region and a concentric ring outside the region), due to the
shock wave generated during microexplosions, were evident. In the case of the baseline glass, no chemistry change was observed
within the region of the microexplosion. However, Al2O3-doped and La2O3-doped glasses showed depletion of the dopant from the edge to the center of the region of the microexplosions, indicating
a chemistry gradient within the regions. Interrogation of the bulk- and laser-treated regions using micro-Raman spectroscopy
revealed no structural change due to the microexplosions and writing within these glasses.
Received: 27 December 2001 / Accepted: 9 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. +1-509/376-3108, E-mail: sk.sundaram@pnl.gov 相似文献
118.
Meenakshi Rajendiran Harsh M Trivedi Dandan Chen Praveen Gajendrareddy Lin Chen 《Molecules (Basel, Switzerland)》2021,26(7)
Periodontal diseases like gingivitis and periodontitis are primarily caused by dental plaque. Several antiplaque and anti-microbial agents have been successfully incorporated into toothpastes and mouthwashes to control plaque biofilms and to prevent and treat gingivitis and periodontitis. The aim of this article was to review recent developments in the antiplaque, anti-gingivitis, and anti-periodontitis properties of some common compounds in toothpastes and mouthwashes by evaluating basic and clinical studies, especially the ones published in the past five years. The common active ingredients in toothpastes and mouthwashes included in this review are chlorhexidine, cetylpyridinium chloride, sodium fluoride, stannous fluoride, stannous chloride, zinc oxide, zinc chloride, and two herbs—licorice and curcumin. We believe this comprehensive review will provide useful up-to-date information for dental care professionals and the general public regarding the major oral care products on the market that are in daily use. 相似文献
119.
P Meenakshi Raja Rao P Saraswathy G Krishnamurty R K Rout S K H Auluck Anurag Shyam I V Kulkarni Dipak H Oza 《Pramana》1989,32(5):627-639
Optical emission spectroscopic studies were carried out to characterise the plasma leading to the estimation of two plasma parameters, electron density and temperature. These experiments were conducted on a 2 kJ plasma device which is equipped with squirrel cage electrode configuration enclosed in a glass vacuum chamber filled with hydrogen at a pressure of 5 mbar. Spectral emissions obtained from each flash were photographed in the region of 4000–6000 Å using one metre Czerny-Turner spectrograph cum monochromator. Detailed examination of the observed features showed that theH β andH λ lines of hydrogen showed significant broadening of the order of 35 Å FWHM which is due to Stark effect expected in high density plasmas. Further several atomic lines of Cu and Zn from the electrode material (brass) showed broadening which was due to quadratic Stark effect. A comparative study of the broadening of lines obtained in DC arc, hollow cathode and plasma focus was made. Electron density from Stark broadened hydrogen lines and quadratic Stark Coefficient C4 for the CuI and ZnI lines were evaluated. The excitation temperature was determined from the line intensity ratio method using CuI lines. 相似文献
120.
The new oxynitride compound of molybdenum, Na3MoO3N was prepared via the azide route. Its crystal structure was solved and refined from X‐ray powder data (orthorhombic, Pmn21, a = 724.63(1), b = 624.98(1), c = 563.86(1) pm, Rp: 9.04 %; Rwp: 9.83 %). The structure consists of isolated [MoO3N]3— tetra‐hedra which are separated by Na+ cations, also in a tetrahedral coordination. It is isostructural to Na3WO3N which is a lower symmetry derivative of the Cu3AsS4 structure. Due to the small difference in the scattering lengths of nitrogen and oxygen, we were unable to distinguish between fully ordered, fully disordered, or partially ordered anions. However, from the positive SHG responses, we can deduce the acentric space group being the correct one and based on the lattice energy calculations, we have been able to identify the position most probably being occupied by nitrogen. 相似文献