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31.
Venu MankadHimadri R. Soni Sanjeev K. GuptaPrafulla K. Jha 《Physica B: Condensed Matter》2011,406(19):3599-3604
We present results of first principles total energy calculations of the structure, electronic and lattice dynamics for beryllium semiboride and its three ternary alloys using generalized gradient and local density approximations under the framework of density functional theory. The generalized gradient approximation is used for all compounds except MgBeB using the Perdew-Burke-Ernzehorf exchange correlation functional while local density approximations use the Perdew-Zunger ultrasoft exchange correlation functional. The calculated ground state structural parameters are in good agreement with those of experimental and previous theoretical studies. The electronic band structure calculations show that Be2B may transform to a semiconductor after Al substitution. A linear response approach to density functional theory is used to calculate phonon dispersion curves and vibrational density of states. The phonon dispersion curves of Be2B and AlBeB are positive indicating a dynamical stablility of the structure for these compounds. The phonon dispersion curves of NaBeB and MgBeB show the imaginary phonons throughout the Brillouin zone, which confirms dynamical instability as indicated in band structures for these alloys. We also present the partial phonon density of states for different species of Be2B and AlBeB to bring out the details of the participation of different atoms in the total phonon density of state, particularly the role played by Al atom. The first time calculated phonon properties are clearly able to bring out the significant effect of isoelectronic substitution in Be2B. 相似文献
32.
The purpose of the paper is to construct a supersymmetric Lagrangian within the framework of classical mechanics which would
be regarded as a candidate for passage to supersymmetric quantum mechanics.
The authors felicitate Prof. D S Kothari on his eightieth birthday and dedicate this paper to him on this occasion. 相似文献
33.
S. K. Soni Sudhir Malik R. K. Shivpuri 《Zeitschrift für Physik A Hadrons and Nuclei》1994,348(4):311-315
Experimental results on some characteristics of high multiplicity (≧45) proton-AgBr interactions at 800 GeV are presented. The results are compared with those in lower multiplicity regions as well as for CNO target. The various parameters investigated here are pseudorapidity distribution, mean normalised multiplicity, mean number of intranuclear collisions and normalised pseudorapidity. 相似文献
34.
We consider the effective action of the chiral quark model to leading order in the number of colors. A set of massive ghost-like Gervais-Lee fermion doublets is introduced which effectively simulate an asymptotically free behavior for the quarks at short distances. This suppresses the vacuum instability and leaves the Wess-Zumino sector unspoiled. At small momenta, we show that the action generated in this way compares well with experiment by performing a chiral expansion up to fourth order. It is found that this action supports stable soliton solutions with baryon number one. Masses, mass-splittings and the sigma-term are estimated in theSU(2) limit.Unité de Recherche des Universités Paris 11 et Paris 6 associée au CNRS 相似文献
35.
In the present paper, we obtain three unified fractional derivative formulae (FDF). The first involves the product of a general
class of polynomials and the multivariableH-function. The second involves the product of a general class of polynomials and two multivariableH-functions and has been obtained with the help of the generalized Leibniz rule for fractional derivatives. The last FDF also
involves the product of a general class of polynomials and the multivariableH-function but it is obtained by the application of the first FDF twice and it involves two independent variables instead of
one. The polynomials and the functions involved in all our fractional derivative formulae as well as their arguments which
are of the typex
ρ
Π
i=1
s
(x
t
i
+α
i
)
σ
i
are quite general in nature. These formulae, besides being of very general character have been put in a compact form avoiding
the occurrence of infinite series and thus making them useful in applications. Our findings provide interesting unifications
and extensions of a number of (new and known) results. For the sake of illustration, we give here exact references to the
results (in essence) of five research papers [2, 3,10, 12, 13] that follow as particular cases of our findings. In the end,
we record a new fractional derivative formula involving the product of the Hermite polynomials, the Laguerre polynomials and
the product ofr different Whittaker functions as a simple special case of our first formula. 相似文献
36.
The pressure dependence of various phonon modes has been investigated through the ferro-paraelectric phase transition. Most
mode frequencies harden before levelling off above the phase transition. Mode Grüneisen parameters are estimated from the
pressure dependence of phonon frequencies. 相似文献
37.
James P. C. Coverdale Dr. Carlos Sanchez‐Cano Dr. Guy J. Clarkson Dr. Rina Soni Prof. Dr. Martin Wills Prof. Dr. Peter J. Sadler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8043-8046
Asymmetric transfer hydrogenation (ATH) is an important process in organic synthesis for which the Noyori‐type RuII catalysts [(arene)Ru(Tsdiamine)] are now well established and widely used. We now demonstrate for the first time the catalytic activity of the osmium analogues. X‐ray crystal structures of the 16‐electron OsII catalysts are almost identical to those of RuII. Intriguingly the precursor complex was isolated as a dichlorido complex with a monodentate amine ligand. The OsII catalysts are readily synthesised (within 1 h) and exhibit excellent enantioselectivity in ATH reactions of ketones. 相似文献
38.
39.
Soni R Cheung FK Clarkson GC Martins JE Graham MA Wills M 《Organic & biomolecular chemistry》2011,9(9):3290-3294
Ru(II) complexes of TsDPEN containing two alkyl groups on the non-tosylated nitrogen atom are poor catalysts for asymmetric transfer hydrogenation of ketones and imines; this observation provides direct evidence for the importance of the N-H interaction in the transition state for ketone reduction. 相似文献
40.
Kokatam S Pandey D Gupta R Krishna R Soni R 《Combinatorial chemistry & high throughput screening》2011,14(8):703-709
Angiogenesis is a promising area of research that targets key therapeutic areas like cancer; wound healing, inflammatory diseases, etc. There is an increasing demand for screening of potential angiogenic and anti-angiogenic agents using sensitive, robust cell-based assays. We have developed a reporter vector containing cis-acting elements that respond to growth factors/angiogenic ligands for use in a cell-based luciferase reporter assay. We performed transient transfection of our reporter gene vector in MCF-7 cells to establish its application for screening of potential pro/anti-angiogenic agents. Reporter gene transactivation studies with different concentrations of fetal bovine serum clearly indicated that the vector is functionally responsive to the angiogenic signals mediated by serum growth factors. We also used endostatin to inhibit transactivation and prove responsiveness to the anti-angiogenic agent. This vector is a promising tool for studying angiogenesis using cell-based reporter gene assays. 相似文献