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201.
Marc Husemann David Mecerreyes Craig J. Hawker James L. Hedrick Rahul Shah Nicholas L. Abbott 《Angewandte Chemie (International ed. in English)》1999,38(5):647-649
Patterned polymer brushes can be prepared by a novel strategy that combines surface‐initiated polymerization and microcontact printing (see picture; μCP SAM indicates the self‐assembled monolayer formed by microcontact printing). The living nature of the polymerization process permits the thickness of the polymer brush and its physical properties to be accurately controlled. 相似文献
202.
The binuclear chiral (salen) Co complexes bearing Lewis acids of Al and Ga catalyze regio- and enantioselective ring opening of terminal epoxides with carboxylic acids. The ring opened product of epichlorohydrin with carboxylic acids followed by cyclization step in the presence of catalyst and base represent straightforward, efficient methods for the synthesis of enatiomerically enriched (>99% ee) valuable terminal epoxides. Strong synergistic effects of different Lewis acid of Co-Al and Co-Ga were exhibited in the catalytic process. 相似文献
203.
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205.
Rahul Sharma Ramesh Chandra AgarwalaVijaya Agarwala 《Journal of magnetism and magnetic materials》2007
The novel low temperature combustion synthesis (LCS) method for the preparation of nanocrystalline W-type BaW hexaferrite i.e. BaNi2Fe16O27 has been carried out by citrate precursor using the sol-to-gel (S–G) followed by gel-to-nanocrystalline (G–N) conversion. Decomposition behaviors and the phases associated therein are investigated by means of thermal analysis (DTA/DTG/TG) and XRD, respectively. Atomic absorption spectroscopy (AAS) has been used to determine the elemental analysis in different conditions. Surface morphology of the nonporous ultra fine particles have been examined by SEM. The TEM micrographs show that the particles of the size of 10 nm were seemed to be agglomerated in the ‘as synthesized’ condition. Room temperature Fe-57 Mossbauer spectrum, MS has showed doublet of ‘as synthesized’ nanocrystalline powder that indicates the superparamagnetic behavior of the material. This effect is further confirmed by vibrating sample magnetometer (VSM) wherein it was noticed that the magnetic field (10 KG max) did not have any effect on the material. The material was annealed at 400, 700 and 1000 °C in the furnace for 4 h. The grain size is found to increase from 10 to 70 nm after annealing at 1000 °C for 4 h. MS after annealing at 700–1000 °C for 4 h, showed that the doublets of ‘as synthesized’ is further resolved into broad sextets due to the presence of both superparamagnetic and ferrimagnetic particles, in the wide size range from 10 to 70 nm. Only slight increase in particle size (from 10 to 15 nm) is noticed after the heat-treatment for 1–3 and 5 min in microwave oven (2.45 GHz with 760 W) but with predominant phase changes. TEM after the heat treatment revealed the presence of microcrystalline nature of grains of the size ∼70 nm. The transformation of the magnetic properties i.e. from superparamagnetic to ferrimagnetic behaviour after heating in microwave oven has been revealed by hysteresis loops under VSM study. The saturation magnetisation, Ms after heat treatment has been seen to increase from 26.7 to 44.5 emu/gm. Remanence and coercivity have also increased four and seven times, respectively. Ms of the as synthesised hexaferrite nano powder and heat-treated powder in microwave oven for 5 min show doublets, confirming the presence of superparamagnetic relaxation in the nano particles as only slight increase in the particle size is associated with the heat treatment. 相似文献
206.
Bhatt PM Ravindra NV Banerjee R Desiraju GR 《Chemical communications (Cambridge, England)》2005,(8):1073-1075
Saccharin, acting as a weak acid, forms salts with basic APIs and these salts have the desirable property of enhanced water solubility. 相似文献
207.
Rahul?BasuEmail author K.?Sridhar 《The European Physical Journal C - Particles and Fields》2004,34(3):367-369
Dilepton production in heavy ion collisions in the intermediate mass region (IMR) has consistently shown an excess over theoretical estimates. An attempt to understand this discrepancy between the observed dilepton pairs and the theoretical estimate is made here through the production of the
meson and estimates obtained by NRQCD calculations. We find that
production offers a satisfactory quantitative picture for explaining the discrepancy.Received: 13 August 2003, Revised: 9 February 2004, Published online: 23 March 2004 相似文献
208.
P. Aurenche Rahul Basu M. Fontannaz 《The European Physical Journal C - Particles and Fields》2008,57(4):681-688
We discuss, in the framework of perturbative QCD at next to leading order, two related observables which are usually considered
to provide tests of the BFKL dynamics: jet–jet correlations at Tevatron energies and forward particle–jet correlations at
HERA. In the first case we study the rapidity gap dependence of the azimuthal correlations and find slightly too strong correlations
at large gap. In the second case we discuss the cross section as well as the azimuthal correlations over a rapidity gap range
of 5 units. We find that the requirement of a forward particle imposes strong kinematical constraints which distort the distributions,
notably at small rapidity gaps. We also show that the decorrelation is stronger in electroproduction than in hadron–hadron
collisions. Unfortunately data are not yet available for comparison. 相似文献
209.
Rahul Chattopadhyay 《Journal of Optimization Theory and Applications》1969,3(4):220-226
The concept of completion of differential games was introduced by Pontryagin in Ref. 1. Here, necessary and sufficient conditions for completion of linear differential games are presented.This work was supported by the Air Force Office of Scientific Research, Contract No. AFOSR 68-1547. 相似文献
210.
Banerjee R Desiraju GR Mondal R Howard JA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(14):3373-3383
The acceptor capabilities of "organic" halogen, CX (X=F, Cl, Br, I), with respect to hydrogen bonding are controversial, and unactivated organic chlorine is generally deemed to be a poor acceptor. Hydrogen bridges of the type O--H...Cl--C are uncommon and occur mainly in an intramolecular situation when the donor group is sterically hindered, so that the formation of intermolecular interactions is difficult. In this paper, intramolecular O--H...Cl--C interactions in a series of chloro-substituted gem-alkynols are studied. We describe various features of this interaction using crystallographic, spectroscopic and computational methods. The O--H...Cl--C interaction occurs in five of the six compounds under consideration here (CDDA, 14DDDA, 15DDDA, 18DDDA, 15MKA). Solution (1)H NMR spectroscopy shows that the interaction is intramolecular and that it is a true hydrogen bond. DFT calculations give a stabilisation energy around 4.0 kcal mol(-1). In the crystal structures of the compounds studied, the intramolecular O--H...Cl--C interactions fit into the overall scheme of cooperative interactions. These structures may be derived from that of the unsubstituted compound DDA by means of synthon exchange and the O--H...Cl--C interaction fares surprisingly well in the presence of competing stronger acceptors. The crystal structures show an unusual degree of modularity for compounds that generally form interactions that are weak and variable. It is noteworthy that the so-called "weak" acceptor, organic chlorine, is able to sustain a good intramolecular hydrogen bridge that is of an attractive and stabilizing nature and which is of potential importance in crystal engineering and supramolecular chemistry. 相似文献