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KL Britton HF Rogers Y Asano T Dairi Y Kato TJ Stillman DW Rice 《Acta crystallographica. Section D, Biological crystallography》1998,53(4):124-126
The novel NAD+-linked opine dehydrogenase from a soil isolate Arthrobacter sp. strain 1C belongs to an enzyme superfamily whose members exhibit quite diverse substrate specificites. Crystals of this opine dehydrogenase, obtained in the presence or absence of co-factor and substrates, have been shown to diffract to beyond 1.8 ? resolution. X-ray precession photographs have established that the crystals belong to space group P21212, with cell parameters a = 104.9, b = 80.0, c = 45.5 ? and a single subunit in the asymmetric unit. The elucidation of the three-dimensional structure of this enzyme will provide a structural framework for this novel class of dehydrogenases to enable a comparison to be made with other enzyme families and also as the basis for mutagenesis experiments directed towards the production of natural and synthetic opine-type compounds containing two chiral centres. 相似文献
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Metlov LS 《Physical review letters》2011,106(16):165506
An alternative approach, nonequilibrium evolution thermodynamics, is compared with the classical Landau approach. A statistical justification of the approach is done with the help of a probability distribution function on an example of a solid with vacancies. Two kinds of kinetic equations are derived in terms of the internal energy and the modified free energy. 相似文献
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The main regularities of structural and phase transformations occurring in solids have been analyzed experimentally and theoretically
within the framework of the concept of manifestation of additional channels providing the dissipation of an elastic energy
introduced into a solid under megaplastic deformation. It has been demonstrated that an active participation of low-temperature
dynamical recrystallization processes, phase transitions of the type crystal ai amorphous state, and thermal effects under
the conditions of an insufficient efficiency of the dislocation and disclination relaxation modes can consistently explain
almost all the experimental results obtained for very severe plastic deformations. 相似文献
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Metlov KL 《Physical review letters》2006,97(12):127205
The energy (magnetostatic, exchange, and Zeeman terms) of a square array of cylindrical submicron dots made of soft ferromagnetic material is calculated analytically and minimized, taking into account the quasiuniformity of dot magnetization. The dependence of the equilibrium energy of the array on the direction of the externally applied magnetic field in the array plane is recovered, exhibiting the fourfold anisotropy. The anisotropy constant is calculated. Its values for different array geometries are in excellent agreement with the recent independent experiments. A new eightfold anisotropy effect is predicted. The theory involves no adjustable parameters. 相似文献
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LUDVÍK BENEŠ KLÁRA MELÁNOVÁ JAN SVOBODA VÍTĚZSLAV ZIMA 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(3-4):289-293
Intercalates of o-, m-, and p-toluidine into α-Zr(HPO4)2 · H2O were prepared and characterized by powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. As follows from IR, toludine molecules are protonated in the interlayer space. Toluidine molecules are arranged in a bimolecular way in the intercalates containing more than 1.5 toluidine molecules per Zr atom. On the other hand, a monolayer of the toluidine molecules is supposed in the intercalates with less than one toluidine molecule per Zr atom. 相似文献
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A thermodynamic model is developed for the melting of an ultrathin lubricant film squeezed between two atomically smooth solid
surfaces. To describe the state of lubricant, an excess volume parameter is introduced; it appears due to the chaos in the
structure of a solid body induced by melting. This parameter increases with the total internal energy upon melting. Thermodynamic
melting and shear melting are described. The dependences of the friction force on the lubricant temperature and the shear
rate of friction surfaces are analyzed. The calculated results are compared to the experimental data. 相似文献
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The free energy as a function of the reaction coordinate (rc) is the key quantity for the computation of equilibrium and kinetic quantities. When it is considered as the potential of mean force, the problem is the calculation of the mean force for given values of the rc. We reinvestigate the PMCF (potential of mean constraint force) method which applies a constraint to the rc to compute the mean force as the mean negative constraint force and a metric tensor correction. The latter allows for the constraint imposed to the rc and possible artefacts due to multiple constraints of other variables which for practical reasons are often used in numerical simulations. Two main results are obtained that are of theoretical and practical interest. First, the correction term is given a very concise and simple shape which facilitates its interpretation and evaluation. Secondly, a theorem describes various rcs and possible combinations with constraints that can be used without introducing any correction to the constraint force. The results facilitate the computation of free energy by molecular dynamics simulations. 相似文献
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