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61.
Uffe Anthoni Carsten Christophersen Michael Gajhede Per H. Nielsen 《Structural chemistry》1992,3(2):121-128
The structure of a trimethylamine oxide (TMAO)-urea 14 complex was investigated by x-ray crystallographic methods. C3H9NO, 4CH4N2O, Mr=315.33, monoclinic P21/n, a=11.004(2), b=9.8259, c=15.419(2),=106.88(4), V=1595.4(2) å3, Z=4, Dx=1.313(1) g cm–3, monochromatized Cu (=1.5418 å),=8.94 cm–1, F(OOO)=680, temperature = 110K, final R=0.067, for 1786 unique observed reflections. Based on these studies and comparison with related compounds a model of the interaction of urea and TMAO with proteins, especially enzymes, is proposed. This is important in the physiology of many organisms, especially elasmobranchs. The counteracting effect of TMAO on urea perturbation of protein structure and function is interpreted in terms of water structure as a balance between the structure breaking effect of urea and the structure-stabilizing effect of TMAO. 相似文献
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In this paper, we consider a variant of the many-to-many location-routing problem, where hub facilities have to be located and customers with either pickup or delivery demands have to be combined in vehicle routes. In addition, several commodities and inter-hub transport processes are taken into account. A practical application of the problem can be found in the timber-trade industry, where companies provide their services using hub-and-spoke networks. We present a mixed-integer linear model for the problem and use CPLEX 12.4 to solve small-scale instances. Furthermore, a multi-start procedure based on a fix-and-optimize scheme and a genetic algorithm are introduced that efficiently construct promising solutions for medium- and large-scale instances. A computational performance analysis shows that the presented methods are suitable for practical application. 相似文献
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Kerstin Zab Detlev Joachimi Eva Novotna Siegmar Diele Carsten Tschierske 《Liquid crystals》2013,40(4):631-637
Abstract Various trimeric co-oligomers combining 2-phenyl-1,3,4-thiadiazole mesogenic moieties with a biphenyl mesogenic moiety were synthesized and their mesomorphic behaviour investigated by polarizing microscopy, calorimetry and X-ray scattering. Such co-oligomeric structures provide an opportunity to combine different mesogenic units. Thus readily accessible homochiral biphenyl mesogenic units were connected with thiadiazole mesogenic units leading to an oligomeric liquid crystal material with ferroelectric properties. 相似文献
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Markus Balmer Dr. Florian Weigend Prof. Dr. Carsten von Hänisch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(19):4914-4919
The N-heterocyclic carbene (NHC)-stabilized phosphinidenide, SIMesPK [SIMes=1,3-bis(2,4,6-trimethylphenyl)imidazolidine-2-ylidene], was used as an (NHC)P-transfer reagent for the synthesis of the low-valent Group 14 ate complexes K[(SIMesP)3E] (E=Ge: 2 , Sn: 3 , Pb: 4 ), which were characterized by 1H NMR, 31P NMR, IR spectroscopy as well as elemental and X-ray analysis. Furthermore, SIMesPK was used in reactions with potassium amides and alkoxides to form the molecular phosphorus–potassium clusters [K4(SIMesP)2(hmds)2] [ 5 , hmds=N(SiMe3)2] and [K6(SIMesP)2(OtBu)4] ( 6 ). Finally, the reaction of SIMesPK with Li[Al(OC4F9)4] led to the potassium-rich ionic compound [(SIMesP)4K5][Al(OC4F9)4] ( 7 ). 相似文献
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