Accelerating Bianchi Type-V Cosmology with Perfect Fluid and Heat Flow in Saez-Ballester Theory

In this paper we discuss the law of variation of scale factor $a = (t^{k}e^{t})^{\frac{1}{n}}$ which yields a time-dependent deceleration parameter (DP) representing a new class of models that generate a transition of universe from the early decelerated phase to the recent accelerating phase. Exact solutions of Einstein's modified field equations with perfect fluid and heat conduction are obtained within the framework of Saez-Ballester scalar-tensor theory of gravitation and the model is found to be in good agreement with recent observations. We find, for n = 3, k = 1, the present value of DP in derived model as q_0 = -0.67 which is very near to the observed value of DP at present epoch. We find that the time-dependent DP is sensible for the present day Universe and give an earmark description of evolution of universe. Some physical and geometric properties of the models are also discussed.Comment: 12 pages, 5 figure

Percolation thresholds in chemical disordered excitable media

The behavior of chemical waves advancing through a disordered excitable medium is investigated in terms of percolation theory and autowave properties in the framework of the light-sensitive Belousov-Zhabotinsky reaction. By controlling the number of sites with a given illumination, different percolation thresholds for propagation are observed, which depend on the relative wave transmittances of the two-state medium considered

High temperature materials for CO2 capture

The potential benefits of precombustion carbon dioxide capture are well documented, and adsorption remains a promising separation process in this area. This paper details work to identify and assess the potential of high temperature adsorbents suitable for precombustion capture. The aim of this paper is to schematically identify adsorbents that are suitable for carbon capture in different temperature ranges. A critical aspect of this work is to assess the materials not only in terms of carbon dioxide isotherms and absolute loading, but to consider the wide range of other properties that are required to achieve an industrially feasible adsorbent - selectivity, cycling capacity, stability, kinetics, high pressure loading, fate of other components (including water, HS, NH, CO and N). It is only when all these requirements are sufficiently met, that an adsorbent can be consider worthy of industrial consideration. A range of analytic screening tests are described to enable a full characterisation of the merit of a specific adsorbent. The adsorbents investigated are zeolites (NaX, calcium chabazite), commercially available hydrotalcite, layered double hydroxides/oxides (LDH/Os), and magnesium double salts. Each operates in a different temperature range and offers potential for integration within an Integrated Gasification and Combined Cycle precombustion process train. Some of the promising and significant conclusions of this work are - •Magnesium double salts present very favourable carbon dioxide isotherms and demonstrate significant carbon dioxide loading and the isotherms are suitable for PSA or TSA operation at high temperature.•LDHs or their derivatives as layered double oxides can adsorb up to 1.5mol/kg CO. Water does not affect CO sorption, and the material has good recyclability in TSA.•The selectivity of hydrotalcite is well documented. However there is no reported literature on the adsorptive behaviour of these materials with respect to trace components - HS and NH. These results are reported.•Calcium chabazite displays useful CO loading potential in a unique temperature range around 200\ua0C.•NaX has the potential to replace Selexol at an operating temperate of 130\ua0C

Wave competition in excitable modulated media.

The propagation of an initially planar front is studied within the framework of the photosensitive Belousov-Zhabotinsky reaction modulated by a smooth spatial variation of the local front velocity in the direction perpendicular to front propagation. Under this modulation, the wave front develops several fingers corresponding to the local maxima of the modulation function. After a transient, the wave front achieves a stationary shape that does not necessarily coincide with the one externally imposed by the modulation. Theoretical predictions for the selection criteria of fingers and steady-state velocity are experimentally validated

Crescimento de calos embriogênicos de milho submetidos ao estresse salino<A NAME="top"></A> Embryogenic callus growth of maize submitted to salt stress

A salinidade do solo é um problema muito importante em áreas irrigadas do semi-árido brasileiro, onde o milho é uma cultura de subsistência. Este trabalho teve como objetivo estudar o efeito de concentrações de NaCl sobre calos embriogênicos, da cultivar Jatinã C3 Anão, uma importante cultivar de milho no Nordeste do Brasil. A indução dos calos foi feita a partir de embriões imaturos assepticamente retirados das sementes e inoculados em meio de cultura N6 suplementado com 2 mg L-1 de 2,4-D. Os calos embriogênicos foram submetidos a diferentes concentrações de cloreto de sódio (0; 50; 100; 150 e 200 mmol L-1 de NaCl), com três repetições durante 60 dias. Os calos submetidos a 100 mmol L-1 de NaCl apresentaram aumento no conteúdo de prolina na ordem de 37% quando comparado com o nível de 50 mmol L-1 de NaCl, sugerindo um efeito positivo da acumulação deste aminoácido em resposta ao estresse salino. Por outro lado, em elevadas concentrações salinas (150 e 200 mmol L-1) observou-se decréscimo no crescimento dos calos, bem como redução nos teores de prolina, provavelmente em função de um aumento da fração não embriogênica dos calos.<br>Soil salinity is a very important problem in irrigated areas of the brazilian semi-arid area, where maize is a subsistence crop. To study the effect of NaCl concentrations in embryogenic calli of Jatinã C3 Anão, an important maize cultivar of the Northest of Brazil, calli were induced using immature embryos aseptically removed from the seeds and grown on N6 medium supplemented with 2 mg L-1 of 2,4-D. To study the effect of salinity in vitro, embryogenic calli were subjected to different concentrations of sodium chloride (0; 50; 100; 150 and 200 mmol L-1 of NaCl), in three replicates, during 60 days. Calli subjected up to100 mmol L-1 NaCl showed proline concentration 37% higher than callus treated with 50 mmol L-1 NaCl. This result suggests a positive effect of proline accumulation at salt stress conditions. However, at the highest concentration tested (150-200 mmol L-1 NaCl) as lower growth and also a lower proline accumulation was observed, probably due to an increase of the non embryogenic fraction of calli