994 resultados para Ramachandra shukla
Resumo:
Sea water electrolysis is one of the promising ways to produce hydrogen since it is available in plentiful supply on the earth. However, in sea water electrolysis toxic chlorine evolution is the preferred reaction over oxygen evolution at the anode. In this work, research has been focused on the development of electrode materials with a high selectivity for oxygen evolution over chlorine evolution. Selective oxidation in sea water electrolysis has been demonstrated by using a cation-selective polymer. We have used a perm-selective membrane (Nafion®), which electrostatically repels chloride ions (Cl−) to the electrode surface and thereby enhances oxygen evolution at the anode. The efficiency and behaviour of the electrode have been characterized by means of anode current efficiency and polarization studies. The surface morphology of the electrode has been characterized by using a scanning electron microscope (SEM). The results suggest that nearly 100% oxygen evolution efficiency could be achieved when using an IrO2/Ti electrode surface-modified by a perm-selective polymer.
Resumo:
The motion due to an oscillatory point source in a rotating stratified fluid has been studied by Sarma & Naidu (1972) by using threefold Fourier transforms. The solution obtained by them in the hyperbolic case is wrong since they did not make use of any radiation condition, which is always necessary to get the correct solution. Whenever the motion is created by a source, the condition of radiation is that the sources must remain sources, not sinks of energy and no energy may be radiated from infinity into the prescribed singularities of the field. The purpose of the present note is to explain how Lighthill's (1960) radiation condition can be applied in the hyperbolic case to pick the correct solution. Further, the solution thus obtained is reiterated by an alternative procedure using Sommerfeld's (1964) radiation condition.
Resumo:
The system CS2 + CH3NO2 shows β=0.315±0.004 over 10-6<ε=|T-Tc| / Tc<2�10-1 with no indication of a classical value ½ even far away from Tc. The diameter shows a curvature and is of the form �c+b ε+fε7 / 8exp(-gεh).
Time-dependent flows of rotating and stratified fluids in geometries with non-uniform cross-sections
Resumo:
Unsteady rotating and stratified flows in geometries with non-uniform cross-sections are investigated under Oseen approximation using Laplace transform technique. The solutions are obtained in closed form and they reveal that the flow remains oscillatory even after infinitely large time. The existence of inertial waves propagating in both positive and negative directions of the flow is observed. When the Rossby or Froude number is close to a certain infinite set of critical values the blocking and back flow occur and the flow pattern becomes more and more complicated with increasing number of stagnant zones when each critical value is crossed. The analogy that is observed in the solutions for rotating and stratified flows is also discussed.
Resumo:
LiNi1/3Mn1/3Co1/3O2, a high voltage and high-capacity cathode material for Li-ion batteries, has been synthesized by three different rapid synthetic methods. viz. nitrate-melt decomposition, combustion and sol-gel methods. The first two methods are ultra rapid and a time period as small as 15 min is sufficient to prepare nano-crystalline LiNi1/3Mn1/3Co1/3O2. The processing parameters in obtaining the best performing materials are optimized for each process and their electrochemical performance is evaluated in Li-ion cells. The combustion-derived LiNi1/3Mn1/3Co1/3O2 sample exhibits large extent of cation mixing (10%) while the other two methods yield LiNi1/3Mn1/3Co1/3O2 with cation mixing <5%. LiNi1/3Mn1/3Co1/3O2 prepared by nitrate-melt decomposition method exhibits superior performance as Li-ion battery cathode material.
Resumo:
The solution for a line source of oscillatory strength kept at the origin in a wall bounding a semi-infinite viscous imcompressible stratified fluid is presented in an integral form. The behaviour of the flow at far field and near field is studied by an asymptotic expansion procedure. The streamlines for different parameters are drawn and discussed. The real characteristic straight lines present in the inviscid problem are modified by the viscosity and the solutions obtained are valid even at the resonance frequency.
Resumo:
Abstract is not available.
Resumo:
The system CS2 + CH3NO2 shows β=0.315±0.004 over 10-6<ε=|T-Tc| / Tc<2-10-1 with no indication of a classical value ½ even far away from Tc. The diameter shows a curvature and is of the form - c+b ε+fε7 / 8exp(-gεh).
Resumo:
Carbon-supported Pt-TiO2 (Pt-TiO2/C) catalysts with varying at. wt ratios of Pt to Ti, namely, 1:1, 2:1, and 3:1, are prepared by the sol-gel method. The electrocatalytic activity of the catalysts toward oxygen reduction reaction (ORR), both in the presence and absence of methanol, is evaluated for application in direct methanol fuel cells (DMFCs). The optimum at. wt ratio of Pt to Ti in Pt-TiO2/C is established by fuel cell polarization, linear sweep voltammetry, and cyclic voltammetry studies. Pt-TiO2/C heattreated at 750 degrees C with Pt and Ti in an at. wt ratio of 2:1 shows enhanced methanol tolerance, while maintaining high catalytic activity toward ORR. The DMFC with a Pt-TiO2/C cathode catalyst exhibits an enhanced peak power density of 180 mW/cm(2) in contrast to the 80 mW/cm(2) achieved from the DMFC with carbon-supported Pt catalyst while operating under identical conditions. Complementary data on the influence of TiO2 on the crystallinity of Pt, surface morphology, and particle size, surface oxidation states of individual constituents, and bulk and surface compositions are also obtained by powder X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive analysis by X-ray, and inductively coupled plasm optical emission spectrometry.
Resumo:
In the face of increasing CO2 emissions from conventional energy (gasoline), and the anticipated scarcity of Crude oil, a worldwide effort is underway for cost-effective renewable alternative energy sources. Here, we review a simple line of reasoning: (a) geologists claim that Much crude oil comes from diatoms; (b) diatoms do indeed make oil; (c) agriculturists Claim that diatoms could make 10-200 times as much oil per hectare as oil seeds; and (d) therefore, sustainable energy could be made from diatoms. In this communication, we propose ways of harvesting oil from diatoms, using biochemical engineering and also a new solar panel approach that utilizes genomically modifiable aspects of diatom biology, offering the prospect of ``milking'' diatoms for Sustainable energy by altering them to actively secrete oil products. Secretion by and milking of diatoms may provide a way around the puzzle of how to make algae that both grow quickly and have a very high oil content.
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A major limitation to progress in primate embryology is the lack of an adequate supply of preimplantation embryos. We describe a method for recovering preimplantation-embryos in bonnet monkeys (Macaca radiata ) using a nonsurgical uterine flushing technique similar to the one previously employed in rhesus monkeys. Forty cyclic females were screened for cervical cannulation, and 10% of these had an impassable cervix. Eleven females suitable for cannulation were selected, and 27 menstrual cycles were monitored over a 5-mo period. Seventy-one percent of the cycles showed estrogen peaks, which were observed between Days 9 and 14 of the cycle. Following natural mating, uterine flushings were performed on Days 5 to 8 of pregnancy (Day 0 = the day following the estrogen peak). Of the 27 recovery attempts, 9 (33.3%) resulted in the recovery of ovulation products, including those of an unfertilized oocyte and empty zona (2 cases), retarded cleavage-stage (4 to 8-cell) embryos (4 cases), morula (1 case) and blastocysts (2 cases). These results show, for the first time, that the nonsurgical uterine flushing technique can be successfully performed to recover uterine-stage preimplantation embryos from bonnet monkeys.
Resumo:
Urban growth identification, quantification, knowledge of rate and the trends of growth would help in regional planning for better infrastructure provision in environmentally sound way. This requires analysis of spatial and temporal data, which help in quantifying the trends of growth on spatial scale. Emerging technologies such as Remote Sensing, Geographic Information System (GIS) along with Global Positioning System (GPS) help in this regard. Remote sensing aids in the collection of temporal data and GIS helps in spatial analysis. This paper focuses on the analysis of urban growth pattern in the form of either radial or linear sprawl along the Bangalore - Mysore highway. Various GIS base layers such as builtup areas along the highway, road network, village boundary etc. were generated using collateral data such as the Survey of India toposheet, etc. Further, this analysis was complemented with the computation of Shannon's entropy, which helped in identifying prevalent sprawl zone, rate of growth and in delineating potential sprawl locations. The computation Shannon's entropy helped in delineating regions with dispersed and compact growth. This study reveals that the Bangalore North and South taluks contributed mainly to the sprawl with 559% increase in built-up area over a period of 28 years and high degree of dispersion. The Mysore and Srirangapatna region showed 128% change in built-up area and a high potential for sprawl with slightly high dispersion. The degree of sprawl was found to be directly proportional to the distances from the cities.
Resumo:
Administration of norethisterone (NET) or NET + estradiol benzoate using an Alzet minipump or as once-a-month intramuscular injection of their depot forms, NET-enanthate (NET-EN) and estradiol valerate (E-val), resulted in azoospermia in all monkeys (n = 13) within 60 to 150 days of treatment. Although addition of depot form of testosterone (T, 20 mg/month) to the regimen restored the behavioral response typical of a normal male, it did not reverse the azoospermic state. Serum T (heightened nocturnal) levels were significantly reduced (> 85%, p < 0.001) in all the treated groups. Evidence for blockade in spermatogenesis following treatment was obtained by DNA flow cytometry. Following withdrawal of treatment, the T level was restored to normalcy within 15 days but 120 days more were required for the animals to exhibit normal sperm counts. In conclusion, the efficacy of once-a-month injection of relatively low doses of NET-EN + E-Val to bring about azoospermia in monkeys, in a relatively short time, has been demonstrated. As the results are uniform and reproducible, it appears desirable that this steroid regimen be tested in man for its contraceptive efficacy.
Resumo:
Urban sprawl is the outgrowth along the periphery of cities and along highways. Although an accurate definition of urban sprawl may be debated, a consensus is that urban sprawl is characterized by an unplanned and uneven pattern of growth, driven by multitude of processes and leading to inefficient resource utilization. Urbanization in India has never been as rapid as it is in recent times. As one of the fastest growing economies in the world, India faces stiff challenges in managing the urban sprawl, while ensuring effective delivery of basic services in urban areas. The urban areas contribute significantly to the national economy (more than 50% of GDP), while facing critical challenges in accessing basic services and necessary infrastructure, both social and economic. The overall rise in the population of the urban poor or the increase in travel times due to congestion along road networks are indicators of the effectiveness of planning and governance in assessing and catering for this demand. Agencies of governance at all levels: local bodies, state government and federal government, are facing the brunt of this rapid urban growth. It is imperative for planning and governance to facilitate, augment and service the requisite infrastructure over time systematically. Provision of infrastructure and assurance of the delivery of basic services cannot happen overnight and hence planning has to facilitate forecasting and service provision with appropriate financial mechanisms.
Resumo:
A key issue on achieving sustainability and sustainable development is through administrative reforms. The book under review, a compilation of ‘good practices’, comes in at a time when the helm of affairs on governance and administrative practices is up for a thorough introspection. This book is a collection of papers presented at the ‘International Conference on Administrative Reforms, Good Practices and their Sustainability’ on 24–25th April 2003 at New Delhi.