Alpha-Glucosidase Folding During Urea Denaturation: Enzyme Kinetics and Computational Prediction

In this study, we investigated structural changes in alpha-glucosidase during urea denaturation. Alpha-glucosidase was inactivated by urea in a dose-dependent manner. The inactivation was a first-order reaction with a monophase process. Urea inhibited alpha-glucosidase in a mixed-type reaction. We found that an increase in the hydrophobic surface of this enzyme induced by urea resulted in aggregation caused by unstable folding intermediates. We also simulated the docking between alpha-glucosidase and urea. The docking simulation suggested that several residues, namely THR9, TRP14, LYS15, THR287, ALA289, ASP338, SER339, and TRP340, interact with urea. Our study provides insights into the alpha-glucosidase unfolding pathway and 3D structure of alpha-glucosidase.     

Tunneling dynamics of superfluid Fermi gas in a triple-well potential

The tunneling dynamics of superfluid Fermi gas in a triple-well potential in the unitarity regime is investigated in the present paper. The fixed points of the (0, 0) mode and the (∏, ∏) mode are given. We find that the interaction parameter U and the coupling strength k could have an extreme effect on the quantum tunneling dynamics. We also find that, in the zero mode, only Josophson oscillation appears. However, for the ∏ mode, the trapping phenomena take place. An irregular oscillation of the particle number in each well could appear by adjusting the scanning period T* . It is noted that if the scanning period is less than a critical point T , the particle number will come back to the fixed point with small oscillation, while if T T* the particle number cannot come back to the fixed point, but with irregular oscillations. The dependence of the critical point T* on the system parameter of coupling strength k is numerically given.     

Cu(OTf)2 catalyzed cross-coupling reaction of 1,3-dicarbonyl derivatives with 2-oxo-1-pyrrolidine compounds

An efficient method for the cross-coupling reactions of 1,3-dicarbonyl compounds with 2-oxo-1-pyrrolidine compounds 1 was developed. Cu(OTf)₂ catalyzed C–C bond forming reactions using substrates 1 with 1,3-dicarbonyl compounds in chloroform, providing the corresponding compounds of 2-oxo-1-pyrrolidine bearing 1,3-dicarbonyl moiety in moderate to good yields.     

外场中任意子的相对论波动方程及其严格解

利用规范不变性,构造了一个任意子在外场中的波动方程,即自旋局域且规范不变的1+2维Klein-Gordon型粒子方程。并发现,外场无论是静电场、还是静磁场以及量子化的电磁场,该方程是严格可解的。给出了相应的解析解形式。     

Preparation of graphene/polyaniline-modified carbon nanotubes and their electrochemical properties in microbial fuel cell

Using chemical vapor deposition methods to prepare carbon nanotubes growing in situ on a carbon felt, graphene and polyaniline were applied to the carbon felt for modifying carbon nanotubes. Microbial fuel cell was constructed with graphene/polyaniline-modified carbon nanotubes as anode, graphite as cathode, and glucose solution as substrate. The effects of electrodes, substrate concentration, and temperature on the properties of microbial fuel cell have been studied. At 38 °C using glucose solution of 1450 mg L^?1 and external resistance of 2500 Ω, the optimum output voltage of 687 mV and removal rate of 83% for chemical oxygen demand were obtained in the microbial fuel cell. The prepared nanomaterials are stable and reusable.     

超导滤波器、超导卫星接收机和超导气象雷达的研究进展

近年来，国际上高温超导微波器件的应用取得了重大突破，国内的高温超导微波应用也取得了重要进展．文章回顾了中国科学院物理研究所在探索具有高性能的高温超导滤波器以及同一芯片上不同类型超导滤波器的集成等方面的一些进展，其中部分滤波器分别在相对带宽（优于0．25％）、返回损耗（优于-22．5dB）、带边陡度（例如大于140dB／MHz）、指定频段的抑制（超过110dB）等方面显示了优异的性能．对于在国内进行的首次高温超导滤波器空间环境模拟试验、首次使用高温超导滤波器子系统的卫星接收机前端地面试验和首次使用高温超导微波子系统的气象雷达的现场试验，文章也做了介绍．     

Polar interaction of polymer host–solvent enables stable solid electrolyte interphase in composite lithium metal anodes

The lithium(Li) metal anode is an integral component in an emerging high-energy-density rechargeable battery.A composite Li anode with a three-dimensional(3 D) host exhibits unique advantages in suppressing Li dendrites and maintaining dimensional stability.However,the fundamental understanding and regulation of solid electrolyte interphase(SEI),which directly dictates the behavior of Li plating/stripping,are rarely researched in composite Li metal anodes.Herein,the interaction between a polar p...     

棱柱型封装Cd的硅纳米管的密度泛函理论研究

运用密度泛函方法在(U)B3LYP/LanL2DZ水平上研究了四棱柱、五棱柱、六棱柱和七棱柱型封装Cd硅纳米管的几何结构和电荷布局、能级和电偶极矩。计算结果表明,四棱柱、六棱柱和七棱柱型Cd硅纳米管的最低能结构都是自旋单重态,四棱柱和五棱柱型Cd硅纳米管畸变比较严重,已经失去管状结构,由于四棱柱型Cd硅纳米管的原子平均结合能最大,它是这四种棱柱型Cd硅纳米管中热力学稳定性最强的。这四种棱柱型Cd硅纳米管的电荷都是由Cd原子转向Si原子的,Cd失去电子,是电荷的施体;Si原子得到电荷,是电荷的受体,且Cd原子与硅原子之间以共价键结合。五棱柱Cd硅纳米管HOMO-LUMO Gap最大,说明它的化学活性最强,而四棱柱型Cd硅纳米管的HOMO-LUMO能隙最小,说明它的化学稳定性最强,不易和其他物质发生化学反应。四棱柱型Cd硅纳米管的总电偶极距为零,说明它的正、负电荷中心重合,该结构是非极性的。五棱柱、六棱柱和七棱柱型Cd硅纳米管是极性的,且五棱柱Cd硅纳米管的极性最强。     

A位Eu掺杂对La0.7Ca0.3MnO3电输运的影响

采用传统的固相反应法制备出了高质量的La_(0.7)Ca_(0.3)MnO_3(其中x=0.00,0.05,0.10,0.15,0.20)系列样品,并对其进行了XRD,电阻-温度测量.实验结果表明,随着Eu掺杂量的增加,样品的金属-绝缘体转变温度朝低温附近移动,峰值电阻增加.通过对A位平均离子半径和尺寸无序度的计算,我们发现,由Eu掺杂导致A位平均离子半径〈rA〉减小,尺寸无序度σ2增大,使晶格畸变加剧,从而削弱了eg巡游电子在Mn3 和Mn4 之间的跃迁,同时促进了自旋极化子的形成.我们还对样品电阻-温度曲线的高温部分进行了拟合,对于x=0.00的样品,曲线可以用非绝热近似下的小极化子模型拟合;当掺杂量为x=0.05,0.10,样品的导电机理符合变程跳跃模型;进一步加大掺杂量,当x=0.15,0.20时,样品的电输运行为可以用晶格极化子与自旋极化子共存来解释.     

One-step synthesis of Fe3O4 nanorods/graphene nanocomposites

A composite of graphene (GE) supported by rod-like Fe₃O₄ nanocrystals has been fabricated by a simple one-step chemical route. X-ray diffraction and transmission electron microscopy results show that the Fe₃O₄ nanorods with diameters in the range of 15?C20 nm and lengths of 150?C200 nm were firmly assembled on the GE nanosheet surface. Magnetic property investigation indicated that the Fe₃O₄/GE composites exhibit a ferromagnetic behavior and possess a saturation magnetization of 50.11?emu?g^?1. Moreover, Fe₃O₄/GE composites showed a very high adsorption capacity of Congo red.