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121.
R. Nacasch Ch. Defoix L. Dobrzynski P.Ladron de Guevara R. Raghavan M. Aguilar-Benitez J. Diaz A. Ferrando E. Gil J.A. Rubio F. Barreiro A. Gurtu L. Montanet A.M. Cooper S.N. Ganguli P.K. Malhotra A. Subramanian 《Nuclear Physics B》1978,135(2):203-223
In this paper we have investigated the properties of the D(1285) and E(1420) meson resonances using the five-body annihilation channels obtained in a large statistics experiment (28 events/μb). The analysis favours the 1+ spin-parity assignment for the D(1285) meson. The dominant decay mode of the D(1285) into is found to be δ(970)π. The situation concerning the E(1420) meson remains confused although not inconsistent with previous analyses. Partial cross sections on resonance production are also presented. 相似文献
122.
Pogrebnyakov AV Redwing JM Raghavan S Vaithyanathan V Schlom DG Xu SY Li Q Tenne DA Soukiassian A Xi XX Johannes MD Kasinathan D Pickett WE Wu JS Spence JC 《Physical review letters》2004,93(14):147006
We report a systematic increase of the superconducting transition temperature T(c) with a biaxial tensile strain in MgB2 films to well beyond the bulk value. The tensile strain increases with the MgB2 film thickness, caused primarily by the coalescence of initially nucleated discrete islands (the Volmer-Weber growth mode.) The T(c) increase was observed in epitaxial films on SiC and sapphire substrates, although the T(c) values were different for the two substrates due to different lattice parameters and thermal expansion coefficients. We identified, by first-principles calculations, the underlying mechanism for the T(c) increase to be the softening of the bond-stretching E(2g) phonon mode, and we confirmed this conclusion by Raman scattering measurements. The result suggests that the E(2g) phonon softening is a possible avenue to achieve even higher T(c) in MgB2-related material systems. 相似文献
123.
The utility of glycine as a safety catch linker for the immobilization of alcohols and phenols to the solid-support is demonstrated by performing a variety of synthetic transformations. 相似文献
124.
N. Mahata K.V. Raghavan V. Vishwanathan Mark A. Keanea 《Reaction Kinetics and Catalysis Letters》2001,72(2):297-302
The gas phase hydrogenation (523-573 K) of phenol has been studied over 1 wt.% Pd/Al2O3 and 1 wt.% Ni/SiO2 catalysts doped with Group I and II promoter oxides. A direct correlation between catalytic activity and the charge transfer capacity of the promoters is presented where hydrogenation is favored by increasing electron donation from the promoter. The Pd catalysts generated cyclohexanone (selectivity > 97%) as the predominant product; selectivity was unaffected by the presence of the alkali or alkaline earth dopants. The Ni system exhibited appreciable hydrogenolysis behavior and charge transfer from the dopants limited the degree of hydrodeoxygenation to favor complete hydrogenation to cyclohexanol. 相似文献
125.
Dilip Raghavan 《Israel Journal of Mathematics》2012,189(1):39-53
We answer a question of Shelah and Steprāns [6] by producing a model of ZFC where there are no strongly separable almost disjoint families. The notion of a strongly separable almost disjoint family is a natural variation on the well known notion of a completely separable almost disjoint family, and is closely related to the metrization problem for countable Fréchet groups. 相似文献
126.
Photoreactions with a Twist: Atropisomerism‐Driven Divergent Reactivity of Enones with UV and Visible Light 下载免费PDF全文
Nandini Vallavoju Avadakkam Sreenithya Anoklase J.‐L. Ayitou Dr. Steffen Jockusch Prof. Dr. Raghavan B. Sunoj Prof. Dr. Jayaraman Sivaguru 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(32):11339-11348
Light‐induced transformation of atropisomeric and achiral enones displays divergent reactivity. Photocyclization leading to 3,4‐dihydroquinolin‐2‐one was observed with achiral enone carboxamide, whereas the atropisomeric enone carboxamides underwent hydrogen abstraction leading to spiro‐β‐lactams. Detailed photochemical, photophysical, and theoretical investigations have provided insight into this divergent reactivity and selectivity. 相似文献
127.
Esperiements were conducted during the summer of 1979 in which field plots oon s Ste. Rosalie clay soil and a Ste. Amable sandy loam soil were subjected to different levels of compaction by machinery, and subsequently treated by moldboard plowing and discing, chiselling and subsoiling by a winged tool. A silage corn crop was grown on all plots and measurements were made of soil bulk densities, penetration resistance of soils and plant yields. The results indicated that the compaction of the soil, if not subsequently loosened by a tillage operation, caused a marked reduction in plant yields. A nnarrow range of dry bulk density produced the optimum silage corn yields in the two experimental soils. The soil densities in this range were obtained by any of the three tillage treatments, as well as by the rototiller treatment, without machinery traffic. 相似文献
128.
In their work on spreading models in Banach spaces, Dilworth et al. (Isr J Math 161:387–411, 2007) introduced the notion of a Suslin lower semi-lattice, a seemingly slight weakening of the notion of a Suslin tree. They posed several problems of a set theoretic nature regarding their notion. In this paper, we make a systematic study of the notion of Suslin lower semi-lattice, answering some of the questions raised by Dilworth, Odell, and Sari. 相似文献
129.
Akanksha Thawani Dr. Ramanan Rajeev Prof. Dr. Raghavan B. Sunoj 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(12):4069-4077
The developments in the area of transition‐metal pincer complexes have opened up new avenues for conversion of saturated hydrocarbons to more useful aromatic compounds under homogeneous reaction conditions. In the backdrop of an interesting series of conversions of unbranched alkanes to benzene, toluene, and xylene (known as the BTX family aromatics) reported by Goldman and co‐workers (Nature Chem. 2011 , 3, 167), we herein present a comprehensive mechanistic picture obtained by using density functional computations. The reaction involves an iridium–PCP‐pincer‐catalyzed dehydroaromatization of hexane to benzene (in which PCP=η3‐C6H3(iPrP)2‐1,3) by using tert‐butylethylene (TBE) as a sacrificial acceptor. The most energetically preferred pathway for a sequence of dehydrogenations is identified to begin with a terminal C? H bond activation of n‐hexane leading to the formation of hex‐1‐ene. Although the initial dehydrogenation of n‐hexane was found to be endergonic, the accompanying exoergic hydrogenation of TBE to tert‐butylethane (TBA) compensates the energetics to keep the catalytic cycle efficient. Subsequent dehydrogenations provide a hexa‐1,3‐diene and then a hexa‐1,3,5‐triene. The pincer bound triene is identified to undergo cyclization to furnish cyclohexadiene. Eventually, dehydrogenation of cyclohexa‐1,3‐diene offers benzene. In the most preferred pathway, the Gibbs free energy barrier for cyclization leading to the formation of cyclohexa‐1,3‐diene is found to exhibit the highest barrier (21.7 kcal mol?1). 相似文献
130.
The objective of this study is to prepare layered organosilicates with enhanced thermal stability that can be used to formulate high‐temperature polymer nanocomposites. Fourier transform infrared (FTIR) spectroscopy, wide‐angle X‐ray diffraction (WAXD), and thermal gravimetric analysis (TGA) characterization results of the modified silicates indicate that the organic pendant group has been chemically grafted on to the backbone of layered silicate and the organically modified apophyllite is thermally stable up to approximately 430°C. The organically modified apophyllite was mixed along with vinyl ester resin and styrene diluent in a sonic dismembrator and the mixture cured to form a nanocomposite specimen. Transmission electron microscopy (TEM) results of the nanocomposites showed mixed morphology with predominant fraction of organosilicates exhibiting an intercalated structure. Tapping mode atomic force microscopy (TMAFM) observation of the nanocomposite showed striated layered silicates dispersed in the resin matrix. The nanocomposites formulated with organosilicates containing reactive terminal pendant group were found to have a higher tensile strain than the nanocomposites formulated with organosilicates containing inert pendant group. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献