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991.
在不同酸度条件下(pH=3.0,6.0,7.4,9.0)诱导人血清白蛋白(HSA)进行质子化或去质子化,以研究其与小分子2,2',4,4',5,6'-六溴联苯醚(BDE154)的结合情况.首先将HSA与BDE154进行半柔性对接,发现BDE154与HSA周围的残基,如:酪氨酸150、赖氨酸195、赖氨酸199等存在较强的疏水相互作用.然后通过分子动力学模拟技术研究HSA在不同质子化状态下的动力学行为和热力学性质,可知过多的正电荷使HSA或者HSA-BDE154的系统稳定性变差.最后对HSA-BDE154的结合自由能进行预测,并对分子动力学模拟结果进行二级结构分析,结果表明HSA-BDE154复合物体系中随着酸度的增大,配体的结合对HSA的去螺旋过程有促进的作用. 相似文献
992.
Zi‐Yi Yu Han Lai Wen‐Juan Zhao Rui Wu Xue‐Sen Liu Li‐Hua Gan 《International journal of quantum chemistry》2017,117(19)
To elucidate the structure of a compound is a necessary step for its practical applications. To study the structure and properties of metal sulfide fullerene Sc2S@C88 detected by mass spectrometry, 11 194 isomers of C88 and 33 isomers of Sc2S@C88 were systematically examined by density functional theory calculations. The calculations show that the two lowest‐energy isomers are Sc2S@C88:81 738 (IPR‐35) and Sc2S@C88:81 735 (IPR‐32), followed by Sc2S@C88:81 729 (IPR‐26), Sc2S@C88:81 712 (IPR‐9), and Sc2S@C88:81 733 (IPR‐30). Structural analysis shows that the first two energetically favored isomers are bridged by the third and fifth energetically favored isomers, which can transfer into each other via direct Stone–Wales rotation. The calculations of temperature effect show that the first two favored isomers become dominant forms of Sc2S@C88 with decreasing temperature and may coexist in the soot. This structural convertibility among favored isomers of Sc2S@C88 suggest a hidden rule that birds of a feather flock together in metal sulfide fullerenes. This rule may decrease the range of candidate cages for the structural identification of a metal sulfide fullerene. IR spectra are simulated for helping the future experimental identification of Sc2S@C88. 相似文献
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994.
A new computationally efficient direct method is applied to estimating unsaturated hydraulic properties during steady-state infiltration and evaporation at soil surface. For different soil types with homogeneous and layered heterogeneity, soil hydraulic parameters and unsaturated conductivities are estimated. Unlike the traditional indirect inversion method, the direct method does not require forward simulations to assess the measurement-to-model fit; thus, the knowledge of model boundary conditions (BC) is not required. Instead, the method employs a set of local approximate solutions to impose continuity of pressure head and soil water fluxes throughout the inversion domain, while measurements act to condition these solutions. Given sufficient measurements, it yields a well-posed system of nonlinear equations that can be solved with optimization in a single step and is thus computationally efficient. For both Gardner’s and van Genuchten’s soil water models, unsaturated hydraulic conductivities and pressure heads (including the unknown BC) can be accurately recovered. When increasing measurement errors are imposed, inversion becomes less accurate, but the solution is stable, i.e., estimation errors remain bounded. Moreover, when the unsaturated conductivity model is known, inversion can recover its parameters; if it is unknown, inversion can recover a nonparametric, piecewise continuous function to which soil parameters can be obtained via fitting. Overall, inversion accuracy of the direct method is influenced by (1) measurement density and errors; (2) rate of infiltration or evaporation; (3) variation of the unsaturated conductivity; (4) flow direction; (5) the number of soil layers. 相似文献
995.
We examine the magnetoresistance (MR) of conducting polymers with interest paid on the role of structural flexibility. Through
Monte Carlo simulation and Green function method, we evaluate the electric transmission for a variety of polymer configurations.
It is found that for a single polymer the transmission displays a complex oscillation and also a parity-dependent periodicity.
For an ensemble of polymers the averaged transmission yields the nonlinear behavior of MR under varying magnetic fields. Interestingly,
more flexible polymers are shown to achieve higher MR, depending on the population and the size of the loops. 相似文献
996.
Q. Z. Yi J. J. Zhang Z. J. Yuan T. S. Zhou 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,75(3):365-372
This paper investigates the effect of integration of
intracellular and extracellular signals on collective dynamics based
on a multicellular system with cell-to-cell communication. Using a
mathematical model of genetic repressilators coupled to quorum
sensing, we show that the changes in parameters of a certain kind of
cis-regulatory input function that quantifies the signal
integration can lead to the change of coupling type from
phase-attractive to phase-repulsive coupling or vice versa.
Consequently, the multicellular system can exhibit, in both coupling
cases, different collective behaviors in terms of synchronization
and clustering. We give a general method of determining coupling
type, elucidate the mechanism of generating these phenomena and
present a criterion for stability of cluster states, mainly by
analyzing phase interaction functions. 相似文献
997.
Wei Ren Weiren Cheng Guan Wang Ye Liu 《Journal of polymer science. Part A, Polymer chemistry》2017,55(4):632-639
Effective antimicrobial polymers have been attracting more interests because of the low propensity to cause drug-resistant microorganisms. The recent progresses in antimicrobial polymers are updated according to the action approaches, that is, antimicrobial polymers with free mobility or fixed on surfaces, respectively. Free antimicrobial polymers kill pathogens majorly via electrostatic interaction followed by disruption of the cell membranes; strong antimicrobial activity of primary/secondary amines, new chemical units, and peptides without facial amphiphilicity are highlighted; and the dependences on amphiphilicity, topology, and self-assembly profiles are summarized. Antimicrobial polymers fixed on surfaces kill pathogens via interaction with the cell membranes of pathogens via electrostatic or hydrophobic interaction; approaches to antimicrobial surfaces based on covalently grafting, anchoring, and bulk-mixing of polymers are summarized; and new designs of sustainable antimicrobial surfaces and hydrogels are highlighted. Deep biology understanding and development strategies of materials are suggested for the future. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 632–639 相似文献
998.
999.
1000.
Seung-Cheol Lee Kiseong Kim Junghyun Kim Jeong Han Yi Soonchil Lee Chaejoon Cheong 《Magnetic resonance imaging》2009
Magnetic resonance (MR) microscopy of up to 1–5-μm resolutions have been reported previously. The tested phantom structures, however, had widths one order of magnitude bigger than the reported resolutions, e.g., spherical beads or capillary tubes of tens-of-micron diameters or wall thicknesses have been imaged. In this study, we fabricated structures having a few micron widths on a silicon wafer and imaged them using our 1-μm-resolution MR microscopy at 14.1 T. Micron scale width structures were, for the first time, resolved by MR microscopy. 相似文献