.Metal hydrides offer the potential to store hydrogen at modest pressures and temperatures with high volumetric efficiencies. The process of charging hydrogen into a metal powder to form the hydride is exothermic. The heat released by the reaction must be removed quickly in order to maintain a rapid charging rate. An effective method for heat removal is to embed a heat exchanger within the metal hydride bed. If the heat released is not removed from the system, the resulting temperature rise of the hydride will reduce the hydrogen absorption rate. Hence, hydrogen storage systems based on hydride materials must include a way to remove the heat generated during the absorption process. The present work aim to size, design and fabricate a metal-hydrogen reactor to study the hydrogen storage in a closed metal-hydrogen reactor. The effects of water cooling temperature (T F ), hydrogen injection pressure (P H2 ) and cooling fluid flow rate () on the mass absorbed of hydrogen (H 2 ) are experimentally investigated and analyzed. Results show that the mass absorbed of H 2 by the metal (LaNi 5 ) raise when T F decreasesand/or when P H2 increases.

This paper investigates the existence and nonexistence of positive solutions for nonlinear higher-order boundary value problem. This can be achieved with the help of suitable theorems by means of the fixed point theory for studying a nonlinear real functions and continuous differential equation in the Banach space of a bounded and closed interval. We show that the mentioned 4th order differential equation has at least one positive solution.

In this paper, we formulate the linear singular and non-singular fractional time-varying descriptor system and present the general exact solutions of both cases in Caputo sense. Furthermore, two illustrated examples are also given to show our new approach

 In recent years several structures, notable almost contact atructure [2], [6], [8], almost r-contact structure [4],[15], almost paracontact structure [9], almost r-paracontact structure [2], almost contact hyperbolicstructure [14] and almost r-contact hyperbolic structure [5] have been defined and studied on a differentiable manifold by many geometers. Some generalized structures, including almost ) ,( 2 1 ee contact structure [10], almost ) ,( 2 1 ee -r-contact structure [11], [12] and unified structure [1], [13] have also been defined. In this paper, We define and study a compendious structure having the following structures as its special cases.

We have synthesized different diastereomers of α- and β-D-glucopyranosyl glycerol without organic solvent, using 15wt% SO42-/SnO2 with different ratios of tungsten oxide and the prepared catalysts were calcined at 400 °C. The present catalytic process is a new route of a synthesis of free salt and metal for the nucleophilic addition of polyol to a monosaccharide. In this article, the catalytic performance of solid acids WO3/SO42-/SnO2 was investigated for the etherification of glycerol with D- glucose in solvent-free conditions. Under optimized conditions, up to 95.82 % yield of glycerol ethers (α- and β-D-glucopyranosyl glycerol ) was obtained. The activity results revealed the promoted catalysts WO3/SO42-/SnO2 show an excellent catalytic selectivity in the etherification of glycerol in comparison of other known catalysts. α- and β-D-glucopyranosyl glycerol synthesized are precursors of amphiphilic surfactants. The reaction progress was monitored with a gas chromatography-mass spectrometry GC-MS, after silylation reaction of the products to ease the separation and identification