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1.
We study the elastic responses of double-(ds) and single-stranded (ss) DNA at external force fields. A double-strand-polymer
elastic model is constructed and solved by path integral methods and Monte Carlo simulations to understand the entropic elasticity,
cooperative extensibility, and supercoiling property of dsDNA. The good agreement with experiments indicates that short-ranged
base-pair stacking interaction is crucial for the stability and the high deformability of dsDNA. Hairpin-coil transition in
ssDNA is studied with generating function method. A threshold force is needed to pull the ssDNA hairpin patterns, stabilized
by base pairing and base-pair stacking, into random coils. This phase transition is predicted to be of first order for stacking
potential higher than some critical level, in accordance with experimental observations. 相似文献
2.
The mechanism of the slowly opened Q-switch operation was investigated thoroughly. Maximum energy extraction from the resonator
could be optimized, and the smallest output beam divergence could be achieved. In this article, we present a detailed analysis
that has numerically verified the mode-selection mechanism in the slowly opened Q-switch operation, and the degree of the
smaller output laser beam divergence that has been achieved. The mechanism of the slowly opened Q-switch operation is the
inherent advantage of the passive saturable absorber in this operation. We can use the maximum energy extraction and the smallest
output beam divergence results of the slowly opened Q-switch operation to design and optimize various passive saturable absorbers:
plastic dye sheets, LiF:F2− color center crystals, Cr4+: YAG crystals, RG1000 color glass filters, and the single crystal semiconductor saturable absorber wafers that are in developed
in our microchip laser systems. 相似文献
3.
4.
Fan Zhang Dang Wu Gao-Lei Wang Shuang Hou Ping Ou-Yang Jin Huang Xiao-Yong Xu 《中国化学快报》2017,28(5):1044-1048
A series of novel 1,2,3-benzotriazin-4-one derivatives were designed,synthesized and their inhibitory activities against leulcotriene A_4 hydrolase aminopeptidase in vitro were evaluated.Many compounds showed moderate to good activities at the concentration of 10 μmol/L.Among them,compound Ⅳ-16 exhibited the highest inhibitory activity up to 80.6% with an IC_(50) of 1.30 ± 0.20 μmol/L The compound Ⅳ-16 was also tested the proliferation inhibitory activities in THP1 human AML cell line and its binding model with LTA_4H enzyme by molecular docking was studied.It indicated that 1,2,3-benzotriazin-4-one was a promising scaffold for further study.The relationship between structure and inhibitory activity was also preliminarily discussed. 相似文献
5.
Two novel,supramolecular,multiferrocenyl rhomboids 5 and 6 have been successfully constructed from newly designed 60 ferrocenyl donor precursor 1 via coordination-driven self-assembly.The structures of all multiferrocenyl rhomboids were characterized by multinuclear NMR(1H and 31P),CSI-TOF-MS, and PM6 semi-empirical molecular simulation,and their electrochemical behaviors have been investigated. 相似文献
6.
We report a new application of the optical tweezers, where a harmonically driven oscillating tweezer is combined with the forward light scattering and lock-in amplification techniques, for probing the mechanics of nanostructures in soft materials in a broad frequency range. Model independent dynamic moduli G and G of the material at a localized, sub-micron area can be measured directly from the displacement and the phase shift of the particle in the oscillating trap. The probe particles can be as small as 200nm and the displacement of the particle was in the range of a few nanometers. To illustrate the new methodology, we show the microscopic viscoelastic properties of a transient polymer network in the vicinity of a silica bead. 相似文献
7.
介绍了原子力显微镜在生物物理领域的最新应用:蛋白质去折叠、DNA拉伸、生物膜受力,通过分析实验得到的力谱,可以获取关于蛋白质、DNA、生物膜结构信息.原子力显微镜不仅能反映测量体系的力学性质,由于其具有独特的时间、空间分辨及实时成像,因而能提供更多信息. 相似文献
8.
A new ZnS/niobate composite was first synthesized through two processes: (1) self-assembly of [Ca2Nb3O10]nn− nanosheets in Zn(NH3)42+ solution; (2) formation of ZnS/niobate composite by adding Na2S to the former reacting system. X-ray diffraction (XRD) result shows that the as-prepared ZnS/niobate composite can be indexed to tetrahedral symmetry with a=5.450(2) and c=16.904(7) Å. The uniform distributions of Zn, Ca, Nb, S and O element in the particles were demonstrated by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The optical property of the composite was characterized by photoluminescence spectra and UV-vis absorption spectra. 相似文献
9.
Ou-Yang Yu Yi-Feng Cheng Shi-Yan Huang Ai-Min Bai Yan-Jun Hu 《Journal of solution chemistry》2011,40(10):1711-1723
The binding of rifampicin (RFP), an anti-tuberculosis agent, to bovine serum albumin (BSA) was studied at physiological conditions
(pH=7.40) by a spectroscopic approach. In the discussion of the quenching mechanism, it was proved that the fluorescence quenching
of BSA by RFP is a result of the formation of a RFP–BSA complex. Binding parameters were determined using the modified Stern-Volmer
equation and Scatchard’s equation to provide a measure of the binding affinity between RFP and BSA. The resulting thermodynamic
parameters ΔG, ΔH, and ΔS at different temperatures indicate that electrostatic interactions play a major role in RFP–BSA association. Site marker
competitive displacement experiments demonstrate that RFP binds with high affinity to the site I (subdomain IIA) of BSA. Furthermore,
the effect of metal ions on the RFP–BSA system was studied, and the specific binding distance r (3.38 nm) between donor and acceptor (RFP) was obtained according to the fluorescence resonance energy transfer (FRET). 相似文献
10.
Ting Ou-Yang 《Journal of Quantitative Spectroscopy & Radiative Transfer》1983,29(5):457-463
A new type of wave existing in the frequency domain is deduced and named a frequency wave. For a homogeneous medium, we have obtained the approximate and rigorous solutions of a frequency shift equation for plane radiation under some special, one-sided or two-sided frequency shift conditions. 相似文献