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571.
Back BB Baker MD Ballintijn M Barton DS Betts RR Bickley AA Bindel R Budzanowski A Busza W Carroll A Chai Z Decowski MP García E Gburek T George N Gulbrandsen K Gushue S Halliwell C Hamblen J Hauer M Heintzelman GA Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Johnson E Kane JL Katzy J Khan N Kucewicz W Kulinich P Kuo CM Lin WT Manly S McLeod D Mignerey AC Nouicer R Olszewski A Pak R Park IC Pernegger H Reed C Remsberg LP Reuter M Roland C Roland G Rosenberg L Sagerer J 《Physical review letters》2006,97(1):012301
We report on measurements of directed flow as a function of pseudorapidity in Au + Au collisions at energies of square root of SNN = 19.6, 62.4, 130 and 200 GeV as measured by the PHOBOS detector at the BNL Relativistic Heavy Ion Collider. These results are particularly valuable because of the extensive, continuous pseudorapidity coverage of the PHOBOS detector. There is no significant indication of structure near midrapidity and the data surprisingly exhibit extended longitudinal scaling similar to that seen for elliptic flow and charged particle pseudorapidity density. 相似文献
572.
Beckmann PA Rosenberg J Nordstrom K Mallory CW Mallory FB 《The journal of physical chemistry. A》2006,110(11):3947-3953
We have observed and modeled the 1H and 19F solid-state nuclear spin relaxation process in polycrystalline 3-(trifluoromethyl)phenanthrene. The relaxation rates for the two spin species were observed from 85 to 300 K at the low NMR frequencies of omega/2pi = 22.5 and 53.0 MHz where CF3 rotation, characterized by a mean time tau between hops, is the only motion on the NMR time scale. All motional time scales (omegatau < 1, omegatau approximately 1, and omegatau > 1) are observed. The 1H spins are immobile on the NMR time scale but are coupled to the 19F spins via the unlike-spin dipole-dipole interaction. The temperature dependence of the observed relaxation rates (the relaxation is biexponential) shows considerable structure and a thorough analysis of Bloch-Wangsness-Redfield theory for this coupled spin system is provided. The activation energy for CF3 rotation is 11.5 +/- 0.7 kJ/mol, in excellent agreement with the calculation in a 13-molecule cluster provided in the companion paper where the crystal structure is reported and detailed ab initio electronic structure calculations are performed [Wang, X.; Mallory F. B.; Mallory, C. W; Beckmann, P. A.; Rheingold, A. L.; Francl, M. M J. Phys. Chem. A 2006, 110, 3954]. 相似文献
573.
The density functional theory method has been applied to gain insights into the regioselectivity of nucleophilic attack and protonation of electron-deficient benzoheterocycle triosmium clusters. We report our computational results on the reaction of the green 46-electron triosmium clusters Os3(CO)(9)(mu3-eta2-(LH))(mu-H) (L = benzoxazole, 1a; benzothiazole, 1b; dihydroquinoline, 1c; 1,3-dehydroindoline, 1d; 4H-3,1-benzoxazine, 1e) with hydride (H-) and proton (H+) in order to elucidate factors affecting the observed differences in the structure of the kinetic products of these reactions. Transition-state calculations for the interconversion of the anionic tautomers resulting from H- attack on the clusters 1a-e show that the activation energies of these anionic clusters are considerably lower than the previously reported barriers for related neutral clusters. Calculations also reveal that the structures of the kinetic products resulting from sequential H-/H+ attack are determined by the protonation process. 相似文献
574.
Hana Vaisocherová Jan Snášel Tomáš Špringer Hana Šípová Ivan Rosenberg Josef Štěpánek Jiří Homola 《Analytical and bioanalytical chemistry》2009,393(4):1165-1172
Understanding the molecular mechanism of HIV-1 integrase (IN) activity is critical to find functional inhibitors for an effective
AIDS therapy. A robust, fast, and sensitive method for studying IN activity is required. In this work, an assay for real-time
label-free monitoring of the IN activity based on surface plasmon resonance was developed. This assay enabled direct monitoring
of the integration of a viral doubled-stranded (ds) DNA into the host genome. The strand transfer reaction was detected by
using two different DNA targets: supercoiled plasmid (pUC 19) and short palindrome oligonucleotide. The effect of the length
of the DNA target on the possibility to monitor the actual process of the strand transfer reaction is discussed. The surface
density of integrated ds-DNA was determined. IN binding to the oligonucleotide complexes and model DNA triplexes in the presence
of various divalent ions as metal cofactors was investigated as well. The assay developed can serve as an important analytical
tool to search for potential strand transfer reaction inhibitors as well as for the study of compounds interfering with the
binding of ds long terminal repeats–IN complexes with the host DNA.
HIV-1 integrase strand transfer activity was monitored in real time using a multichannel surface plasmon resonance biosensor.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
575.
B. A. Rosenberg 《Macromolecular Symposia》1987,7(1):17-26
A review of new results concerning kinetics, thermodynamics and mechanism of epoxy oligomers curing with various nucleophilic agents (amines, phenols, carboxylic acids) has been made. The concept of the mechanism of such reactions is formulated on the basis of this study. Kinetic data obtained are interpreted within the framework of cyclic transition state. The addition of nucleophilic agent to epoxy ring is rather complicated. It results from preliminary formation of homo- and heteroassociates of reaction system components which finally form reactive cyclic heteroassociates. Reaction products are formed as a result of monomolecular rearrangement with synchronous transfer of electrons in the reactive cyclic heteroassociates. 相似文献
576.