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101.
Subrata?Kundu Anjali?Pal Sujit?Kumar?Ghosh Sudip?Nath Sudipa?Panigrahi Snigdhamayee?Praharaj Soumen?Basu Tarasankar?PalEmail author 《Journal of nanoparticle research》2005,7(6):641-650
Chelating ligands with β-diketone skeleton have been employed for the first time as reductant to produce ligand stabilized
gold nanoparticles of different shapes out of aqueous HAuCl4 solutions. Evolution of stable gold nanoparticles happens to be first order with respect to gold particles having rate constants
∼
∼10−2 min−1 and subsequent chlorine insertion in the β-diketone skeleton is reported as a general feature. Spherical or triangular or
hexagonal particle evolution goes selectively under the influence of different β-diketones in terms of capping and reducing
capabilities of the reductants. 相似文献
102.
Vishwakarma RA Vehring S Mehta A Sinha A Pomorski T Herrmann A Menon AK 《Organic & biomolecular chemistry》2005,3(7):1275-1283
Glycerophospholipid flip-flop across biogenic membranes such as the endoplasmic reticulum (ER) is a fundamental feature of membrane biogenesis. Flip-flop requires the activity of specific membrane proteins called flippases. These proteins have yet to be identified in biogenic membranes and the molecular basis of their action is unknown. It is generally believed that flippase-facilitated glycerophospholipid flip-flop across the ER is governed by the stereochemistry of the glycerolipid, but this important issue has not been resolved. Here we investigate whether the ER flippase stereochemically recognizes the glycerophospholipids that it transports. To address this question we selected phosphatidylinositol (PI), a biologically important molecule with chiral centres in both its myo-inositol headgroup and its glycerol-lipid tail. The flip-flop of PI across the ER has not been previously reported. We synthesized fluorescence-labeled forms of all four diastereoisomers of PI and evaluated their flipping in rat liver ER vesicles, as well as in flippase-containing proteoliposomes reconstituted from a detergent extract of ER. Our results show that the flippase is able to translocate all four PI isomers and that both glycerol isomers of PI flip-flop across the ER membrane at rates similar to that measured for fluorescence-labeled phosphatidylcholine. Our data have important implications for recent hypotheses concerning the evolution of distinct homochiral glycerophospholipid membranes during the speciation of archaea and bacteria/eukarya from a common cellular ancestor. 相似文献
103.
Letp be any odd prime number. Letk be any positive integer such that
. LetS = (a
1,a
2,...,a
2p−k
) be any sequence in ℤp such that there is no subsequence of lengthp of S whose sum is zero in ℤp. Then we prove that we can arrange the sequence S as follows:
whereu ≥v,u +v ≥ 2p - 2k + 2 anda -b generates ℤp. This extends a result in [13] to all primesp andk satisfying (p + 1)/4 + 3 ≤k ≤ (p + 1)/3 + 1. Also, we prove that ifg denotes the number of distinct residue classes modulop appearing in the sequenceS in ℤp of length 2p -k (2≤k ≤ [(p + 1)/4]+1), and
, then there exists a subsequence of S of lengthp whose sum is zero in ℤp. 相似文献
(1) |
104.
The kinetics of oxidation of dimethyl, dipropyl, and diphenyl sulfides by pyridinium chloro chromate in chlorobenzene–nitrobenzene mixtures are reported. The rate data show Michaelis–Menten behavior. The oxidation process is catalyzed by the organic acids like dichloro and trichloro acetic acids. The rate-determining step appears to be a unimolecular decomposition of a complex of the reactants. 相似文献
105.
106.
Anuradha Sharma Gurmeet K. Bakshi V. C. Dumir Madhu Raka 《Finite Fields and Their Applications》2004,10(4):133
Let q be an odd prime power and p be an odd prime with gcd(p,q)=1. Let order of q modulo p be f,
and qf=1+pλ. Here expressions for all the primitive idempotents in the ring Rpn=GF(q)[x]/(xpn−1), for any positive integer n, are obtained in terms of cyclotomic numbers, provided p does not divide λ if n2. The dimension, generating polynomials and minimum distances of minimal cyclic codes of length pn over GF(q) are also discussed. 相似文献
107.
Preema C. Thomas Lanka Bhushan Kumar A. Anuradha S. Aruna Ginson P. Joseph P. Sagayaraj 《Journal of Crystal Growth》2006,290(2):560-564
Growth of good optical quality single crystals of l-arginine diiodate (abbreviated as LADI), a semiorganic nonlinear optical (NLO) material is reported. Crystals of dimension up to were obtained from its aqueous solution by slow solvent evaporation technique. The crystals were characterized by single crystal XRD, FTIR, optical absorption spectrum, microhardness, dielectric and photoconductivity studies. The DTA and TGA traces of LADI confirm the decomposition of the sample at 145 °C. 相似文献
108.
Schlieren measurements of the gradients of the concentration field around a KDP crystal growing from its aqueous solution are reported. The measurement of the concentration gradient field is important for crystal growth because it controls the rate of solute transport from the bulk of the solution to the crystal surface. In the crystal vicinity, the concentration gradients have a three dimensional distribution. The concentration gradient field has been imaged using monochrome schlieren technique. Four view angles, namely 0, 45, 90 and 135° have been utilized. By interpreting the schlieren images as projection data of solute concentration gradient, the three‐dimensional concentration gradient field around the crystal has been determined using an algebraic reconstruction technique. At low supersaturation levels, the growth process is accompanied by weak fluid movement during which diffusion effects are significant. At higher levels of supersaturation and large crystal size, a well‐defined convective plume around the growing crystal is observed. Reconstruction of concentration gradients around the crystal explains the preferential growth rates of various faces of the crystal. The non‐circular shape of the crystal is seen to affect the symmetry of the distribution of concentration gradients in its vicinity. The effect of crystal morphology on the orientation of convection currents rising from the crystal surface has also been brought out on the basis of the reconstructed concentration gradients distribution in the growth chamber. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
109.
110.