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The structural, electronic, elastic, mechanical and thermal properties of isostructural and isoelectronic nonmagnetic RA13 (R = Yb, Lu and Sc) compounds, which crystallize in AuCu-3-type structure, are studied using first principles density functional theory based on full potential linearized augmented plane wave (FP-LAPW) method. The calculations are carried out within PBE-GGA, WC-GGA and PBE-sol GGA for the exchange correlation potential. Our calculated ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B') are in good agreement with the available experimental and other theoretical results. We predict the elastic constants for these compounds using GGA approximations. All the compounds are found to be brittle in nature in accordance with Pugh's criteria. The computed electronic band structures and density of states show metallic character of these compounds. The elastic properties including Poisson's ratio (σ), Young's modulus (E), shear modulus (GH) and anisotropy factor (A) are also determined using the Voigt-Reuss-Hill (VRH) averaging scheme. The average sound velocities (vm), density (ρ) and Debye temperature (θH)) of these RA13) compounds are also estimated from the elastic constants. We first lime report the variation of elastic constants, elastic moduli, sound velocities and Debye temperatures of these compounds as a function of pressure. [ABSTRACT FROM AUTHOR]

Increased demand of fossil fuels has lead to its shortfall and also for an urge for the search of alternative source of energy, which is non-polluting. Biohydrogen is an ideal fuel of future as it can be produced from different types of wastes, solids or liquids, rich in organic matter and it does not produce any types of green house gases when combusted. Present work was carried out to enhance the biohydrogen production from de-oiled rice bran by pretreatment methods. Presence of high amount of carbohydrate (39% cellulose and 31% hemicellulose) and less lignin (4%) makes it an attractive feedstock for conversion into a variety of value-added products. De-oiled rice bran was taken as substrate and Clostridium acetobutylicum NCIM 2877 was used as seed culture for the fermentative biohydrogen production. Substrate was pretreated with different fungi, Aspergillus niger, Trichoderma viride, and Phenerocheate chryosporium. After three days of pretreatment with Phenerocheate chryosporium maximum of 93 ± 2.0 ml volumetric biohydrogen with conversion efficiency of 69.55 ± 5.5 % was obtained whereas maximum production of 112 ± 2.5 ml with a conversion efficiency of 69.55 ± 0.45 % was achieved by 7 days pretreatment with Trichoderma viride. Therefore, by pretreatment of various complex biomasses, production of biohydrogen can be enhanced. [ABSTRACT FROM AUTHOR]