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71.
Sridevi V. Shinde Sarika Sinha Prof. Dr. Kumaravel Somasundaram Prof. Dr. Ashoka G. Samuelson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(39):12278-12291
Neutral half‐sandwich organometallic ruthenium(II) complexes of the type [(η6‐cymene)RuCl2(L)] ( H1 – H10 ), where L represents a heterocyclic ligand, have been synthesized and characterized spectroscopically. The structures of five complexes were also established by single‐crystal X‐ray diffraction confirming a piano‐stool geometry with η6 coordination of the arene ligand. Hydrogen bonding between the N? H group of the heterocycle and a chlorine atom attached to Ru stabilizes the metal–ligand interaction. Complexes coordinated to a mercaptobenzothiazole framework ( H1 ) or mercaptobenzoxazole ( H6 ) showed high cytotoxicity against several cancer cells but not against normal cells. In vitro studies have shown that the inhibition of cancer cell growth involves primarily G1‐phase arrest as well as the generation of reactive oxygen species (ROS). The complexes are found to bind DNA in a non‐intercalative fashion and cause unwinding of plasmid DNA in a cell‐free medium. Surprisingly, the cytotoxic complexes H1 and H6 differ in their interaction with DNA, as observed by biophysical studies, they either cause a biphasic melting of the DNA or the inhibition of topoisomerase IIα activity, respectively. Substitution of the aromatic ring of the heterocycle or adding a second hydrogen‐bond donor on the heterocycle reduces the cytotoxicity. 相似文献
72.
Stuart Lipsitz Garrett Fitzmaurice Debajyoti Sinha Nathanael Hevelone Jim Hu Louis L. Nguyen 《Journal of computational and graphical statistics》2017,26(3):734-737
Medical studies increasingly involve a large sample of independent clusters, where the cluster sizes are also large. Our motivating example from the 2010 Nationwide Inpatient Sample (NIS) has 8,001,068 patients and 1049 clusters, with average cluster size of 7627. Consistent parameter estimates can be obtained naively assuming independence, which are inefficient when the intra-cluster correlation (ICC) is high. Efficient generalized estimating equations (GEE) incorporate the ICC and sum all pairs of observations within a cluster when estimating the ICC. For the 2010 NIS, there are 92.6 billion pairs of observations, making summation of pairs computationally prohibitive. We propose a one-step GEE estimator that (1) matches the asymptotic efficiency of the fully iterated GEE; (2) uses a simpler formula to estimate the ICC that avoids summing over all pairs; and (3) completely avoids matrix multiplications and inversions. These three features make the proposed estimator much less computationally intensive, especially with large cluster sizes. A unique contribution of this article is that it expresses the GEE estimating equations incorporating the ICC as a simple sum of vectors and scalars. 相似文献
73.
Papia Datta Dibakar Sardar Uttam Panda Ajanta Halder Nabin Baran Manik Chun‐Jung Chen Chittaranjan Sinha 《应用有机金属化学》2016,30(5):323-334
Os(II) hydridocarbonyl complexes of coumarinyl azoimidazoles, [Osh(CO)(PPh3)2(CZ‐4R‐R′)]0/+ ( 3 , 4 ) (CZ‐R‐H = 2‐(coumarinyl‐6‐azo)‐4‐substituted imidazole or 1‐alkyl‐2‐(coumarinyl‐6‐azo)‐4‐substituted imidazole), were characterized from spectroscopic data and the single‐crystal X‐ray data for one of the complexes, [Osh(CO)(PPh3)2(CZ‐4‐Ph)] ( 3c ) (CZ‐4‐Ph = 2‐(coumarinyl‐6‐azo)‐4‐phenylimidazolate), confirmed the structure. The complexes show higher emission (quantum yield ? = 0.0163–0.16) and longer lifetime (τ = 1.4–10.3 ns) than free ligands (? = 0.0012–0.0185 and τ = 0.685–1.306 ns). Cyclic voltammetry shows quasi‐reversible metal oxidation at 0.67–0.94 V for [Os(III)/Os(II)] and 1.21–1.36 V for [Os(IV)/Os(III)] and subsequent azo reductions (?0.68 to ?0.95 V for [? N?N? ]/[? N N? ]? and irreversible < ?1.2 V for [? N N? ]?/[? N? N? ]2?) of the chelated coumarinyl azoimidazole. The complexes are photostable and show better photovoltaic power conversion efficiency than free ligands. Also, the complexes were used as catalysts for the oxidation of primary/secondary alcohols to aldehydes/ketones using oxidizing agents like N‐methylmorpholine N‐oxide, t‐BuOOH and H2O2. Density functional theory computation was carried out from the optimized structures and the data obtained were used to interpret the electronic and photovoltaic properties. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
74.
75.
Studies on different phases in the Y-Ba-Cu-O system have revealed that TC around 90 K is obtainable with different Cu /Cu ratios provided the correct oxygen proportion is maintained. 相似文献
76.
The present work deals with the late time evolution of the linear density contrast in the dark energy models reconstructed from the jerk parameter. It is found that the non-interacting models are favoured compared to the models where an interaction is allowed in the dark sector. 相似文献
77.
N. Senthilkumar Y. S. Somannavar Brajesh Kumar Sinha G. K. A. S. S. Narayan Ramesh Dandala 《合成通讯》2013,43(2):268-276
A simple synthetic route for active metabolites of carvedilol is reported. The metabolites 4′-hydroxycarvedilol and 5′-hydroxycarvedilol have exhibited high activity for β-blockade. We have disclosed syntheses of 4′-hydroxycarvedilol and 5′-hydroxycarvedilol from commercially available vanillin and isovanillin, respectively. 相似文献
78.
Bharati Banerjee D.K. Sinha 《International Journal of Mathematical Education in Science & Technology》2013,44(3):261-265
This paper, after analysing the meaning of ‘applied mathematics’, seeks to explore and set forth some broad outlines of the pedagogical implications of studies in the application of mathematics. 相似文献
79.
80.
Rate constants of the reactions of O(3P) atoms with Br2 and NO2 over the temperature range 220-950 K
The kinetics of the reactions of Br2 and NO2 with ground state oxygen atoms have been studied over a wide temperature range, T = 220-950 K, using a low-pressure flow tube reactor coupled with a quadrupole mass spectrometer: O + NO2 → NO + O2 (1) and O + Br2 → Br + BrO (2). The rate constant of reaction (1) was determined under pseudo–first-order conditions, either monitoring the kinetics of O-atom or NO2 consumption in excess of NO2 or of the oxygen atoms, respectively: k1 = (6.1 ± 0.4) × 10−12 exp((155 ± 18)/T) cm3 molecule−1 s−1 (where the uncertainties represent precision at the 2σ level, the estimated total uncertainty on k1 being 15% at all temperatures). The temperature dependence of k1, found to be in excellent agreement with multiple previous low-temperature data, was extended to 950 K. The rate constant of reaction (2) determined under pseudo–first-order conditions, monitoring the kinetics of Br2 consumption in excess of O-atoms, showed upward curvature at low and high temperatures of the study and was fitted with the following three-parameter expression: k2 = 9.85 × 10−16 T1.41 exp(543/T) cm3 molecule−1 s−1 at T = (220-950) K, which is recommended from the present study with an independent of temperature conservative uncertainty of 15% on k2. 相似文献