17,166 research outputs found

    Optical Absorption in B13_{13} Cluster: A Time-Dependent Density Functional Approach

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    The linear optical absorption spectra of three isomers of planar boron cluster B13_{13} are calculated using time-dependent spin-polarized density functional approach. The geometries of these cluster are optimized at the B3LYP/6-311+G* level of theory. Even though the isomers are almost degenerate, the calculated spectra are quite different, indicating a strong structure-property relationship. Therefore, these computed spectra can be used in the photo-absorption experiments to distinguish between different isomers of a cluster.Comment: Version2: Latex and hyperref enabled. Minor typos corrected. 4 figures, 2 pages. Accepted manuscript. To appear in AIP Conference Proceeding

    Remarkable Hydrogen Storage on Beryllium Oxide Clusters: First Principles Calculations

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    Since the current transportation sector is the largest consumer of oil, and subsequently responsible for major air pollutants, it is inevitable to use alternative renewable sources of energies for vehicular applications. The hydrogen energy seems to be a promising candidate. To explore the possibility of achieving a solid-state high-capacity storage of hydrogen for onboard applications, we have performed first principles density functional theoretical calculations of hydrogen storage properties of beryllium oxide clusters (BeO)n_{n} (n=2 -- 8). We observed that polar BeO bond is responsible for H2_{2} adsorption. The problem of cohesion of beryllium atoms does not arise, as they are an integral part of BeO clusters. The (BeO)n_{n} (n=2 -- 8) adsorbs 8--12 H2_{2} molecules with an adsorption energy in the desirable range of reversible hydrogen storage. The gravimetric density of H2_{2} adsorbed on BeO clusters meets the ultimate 7.5 wt% limit, recommended for onboard practical applications. In conclusion, beryllium oxide clusters exhibit a remarkable solid-state hydrogen storage.Comment: This document is the Accepted Manuscript version of a Published Work that appeared in final form in JPCC, copyright American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see , see http://pubs.acs.org/doi/abs/10.1021/jp410994

    STATISTICAL MEDIA OPTIMIZATION FOR LUTEIN PRODUCTION FROM MICROALGAE Auxenochlorella protothecoides SAG 211-7A

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    In this study, the heterotrophic production potential of the secondary carotenoid lutein by the green microalgae Auxenochlorella protothecoides SAG 211-7a was investigated. A sequential statistical technique was applied to optimize modified bold’s basal media (MBB) to enhance the lutein production from microalgae Auxenochlorella protothecoides SAG 211-7a. Taguchi orthogonal array method was applied to select the various independent variables which affect the lutein production. It showed that sucrose, yeast extract, MgSO4.7H2O and EDTA were the significant factors affect the lutein production. Further, to increase the lutein yield and to study the interaction between these factors response surface methodology (RSM) was employed. The statistical model was validated with respect to lutein production under the conditions predicted by the model containing sucrose 14.0 g/l, yeast extract 3.0 g/l, MgSO4.7H2O 0.8 g/l and EDTA 0.76 g/l. The production of lutein obtained experimentally using the above medium was 1303 ± 25.32 μg/l, which is in correlation with the predicted value of 1337.21 g/l by the RSM regression study. Thus after sequential statistical media optimization strategy a 5-fold enhancement in lutein production was achieved

    First principles electron-correlated calculations of optical absorption in magnesium clusters

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    In this paper, we report large-scale configuration interaction (CI) calculations of linear optical absorption spectra of various isomers of magnesium clusters Mgn_{n} (n=2--5), corresponding to valence transitions. Geometry optimization of several low-lying isomers of each cluster was carried out using coupled-cluster singles doubles (CCSD) approach, and these geometries were subsequently employed to perform ground and excited state calculations using either the full-CI (FCI) or the multi-reference singles-doubles configuration interaction (MRSDCI) approach, within the frozen-core approximation. Our calculated photoabsorption spectrum of magnesium dimer (Mg2_{2}) isomer is in excellent agreement with the experiments both for peak positions, and intensities. Owing to the sufficiently inclusive electron-correlation effects, these results can serve as benchmarks against which future experiments, as well as calculations performed using other theoretical approaches, can be tested.Comment: 23 pages and 21 figures of main tex

    Violation of Porod law in a freely cooling granular gas in one dimension

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    We study a model of freely cooling inelastic granular gas in one dimension, with a restitution coefficient which approaches the elastic limit below a relative velocity scale v. While at early times (t << 1/v) the gas behaves as a completely inelastic sticky gas conforming to predictions of earlier studies, at late times (t >> 1/v) it exhibits a new fluctuation dominated phase ordering state. We find distinct scaling behavior for the (i) density distribution function, (ii) occupied and empty gap distribution functions, (iii) the density structure function and (iv) the velocity structure function, as compared to the completely inelastic sticky gas. The spatial structure functions (iii) and (iv) violate the Porod law. Within a mean-field approximation, the exponents describing the structure functions are related to those describing the spatial gap distribution functions.Comment: 4 pages, 5 figure

    Cellulitis Due to Salmonella infantis.

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    Bacteria of the genus Salmonella are highly adapted for the growth in both humans and animals and cause a wide spectrum of disease. The growth of Serotypes S. typhi and S. paratyphi is restricted to human hosts, in whom these organisms cause enteric (typhoid) fever. The remaining Serotypes (non typhoidal Salmonella or NTS) can colonize the gastrointestinal tracts of the broad range of animals, including mammals, reptiles, birds and insects. The usual clinical presentation of non-typhoidal salmonellae (NTS) infection is self limited gastroenteritis; however bacteremia and focal extra intestinal infection may occur. However salmonella localization to the skin presenting as cutaneous ulceration is regarded as a rare event. Rates of morbidity and mortality associated with NTS are highest among the elderly, infants, and immunocompromised individuals, including those with hemoglobinopathies, HIV infection, or infections that cause blockade of the reticuloendothelial system. We isolated S.infantis in 50 years old man with left leg cellulitis. The serotype was confirmed at Central Research Institute, Kasauli

    UNUSAUAL PRESENTATION OF SUBMANDIBULAR DUCT AND GLAND CALCUI: CASE REPORT

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    Sialolithiasis is one of the most common pathologies of the submandibular gland; sialoliths account for about 80 percent of all salivary duct calculi.The majority of sialolith occurs in the submandibular gland or its duct and is common cause of acute and chronic infection. Salivary stones larger than 15 mm are classified as giant sialoliths. They are uncommon in the practice of otolaryngology, and their management has always been a therapeutic challenge. This report presents the two unusual and rare cases of large sialolith of the submandibular duct as well as gland measuring 70x11mm and 54x25mm respectively.
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