钙离子调控微丝切割蛋白中A6亚基解折叠的单分子力谱研究

在生命活动中,金属离子扮演了非常重要的角色.微丝切割蛋白(adseverin)需要钙离子的活化才能行使其切割肌动蛋白微丝的功能.本文通过基于原子力显微镜的单分子力谱研究了微丝切割蛋白C端末的A6亚基在结合钙离子前后的力学解折叠机理.实验结果显示:在未结合钙离子时,A6的解折叠表现为两态过程;在结合钙离子后A6力学稳定性显著提高;同时,钙离子的结合使得A6解折叠过程中出现稳定的中间态.通过对中间态的链长的分析,我们推测了中间态对应着A6的N端部分解折叠.而这一部分的解折叠可以使得掩藏在该结构后的A5亚基中肌动蛋白微丝结合位点暴露,从而促使微丝切割蛋白执行功能.我们的实验结果为理解微丝切割蛋白的工作原理提供了新的实验证据.     

无锂助熔剂B_2O_3对Li_(1.3)Al_(0.3)Ti_(1.7)(PO_4)_3固体电解质离子电导率的影响

采用固相法制备锂离子电池用固体电解质磷酸钛锂铝Li_(1.3)Al_(0.3)Ti_(1.7)(PO_4)_3(LATP),研究了不同烧结温度以及助熔剂对LATP固体电解质离子电导率的影响.采用X射线衍射、能谱分析、扫描电镜和交流阻抗等方法,研究样品的结构特征、元素含量、形貌特征以及离子导电性能.结果表明,在900?C烧结可以获得结构致密、离子电导率较高的纯相LATP陶瓷固体电解质.与添加助熔剂Li BO2的样品进行对比实验发现,采用B_2O_3代替LiBO_2作为助熔剂也可以提高烧结样品的离子电导率,并且电解质的离子电导率随助熔剂添加量的增大,先增大后减小,其中添加质量百分比为2%的B_2O_3的样品具有最高的室温离子电导率,为1.61×10~(-3)S/cm.     

光纤放大器放大自发辐射特性与高温易损点位置

在高功率光纤放大器实验中,时常发现增益光纤抽运注入熔接点后10—50 cm处容易发生光纤烧毁现象.为了对该现象进行理论预测,基于光纤激光器速率方程模型和增益光纤的热传导模型,从种子功率、抽运功率和抽运吸收三个方面对掺镱双包层光纤放大器中的放大自发辐射(ASE)和温度特性进行研究.结果表明,在放大倍率较高、ASE较为严重等情况下,光纤放大器中的最高温度点一般不在抽运注入的熔接点处,而在距离熔接点10—50 cm处,与实验中发现光纤烧毁的位置基本符合.从光纤放大器的ASE抑制、最高温度点温度控制角度出发,对光纤放大器在种子功率、抽运功率、抽运吸收、放大倍率和抽运波长等方面的设计给出了指导性的建议.     

A feasible approach to field concentrators of arbitrary shapes

We propose a simple method to design field concentrators of arbitrary shapes based on Fabry–Pérot resonances. The material parameters are feasible in terms of metallic layered structures and gradient index dielectrics. The functionalities are well confirmed by numerical simulations.     

Dynamics of Spiral Waves Induced by Periodic Mechanical Deformation with Phase Difference

The dynamics of spiral waves under the influences of periodic mechanical deformation are studied. Here, the mechanical deformation propagating along the medium with phase differences are considered. It is found that weak mechanical deformation may lead to resonant drift of spiral waves. The drift direction and velocity can be changed by the wave length of the deformation. Strong mechanical deformation may result in breakup of spiral waves. The characteristics of breakup are discussed. The critical amplitudes are determined by two factors, i.e. the wave length and frequency of the periodic mechanical deformation. When the wave length of mechanical deformation is comparable to the spiral wave, simulation shows that the critical amplitude is substantially increased. As the frequency of the mechanical deformation is around 1.5 times of the spiral wave, the critical amplitudes are minimal.     

A New Proxy Electronic Voting Scheme Achieved by Six-Particle Entangled States

In this paper, we use quantum proxy signature to construct a new secret electronic voting scheme. In our scheme, six particles entangled states function as quantum channels. The voter Alice, the Vote Management Center Bob, the scrutineer Charlie only perform two particles measurements on the Bell bases to realize the electronic voting process. So the scheme reduces the technical difficulty and increases operation efficiency. We use quantum key distribution and one-time pad to guarantee its unconditional security. The significant advantage of our scheme is that transmitted information capacity is twice as much as the capacity of other schemes.     

La65X35(X=Ni,Al)非晶合金原子结构的第一性原理研究

运用基于密度泛函理论的第一性原理分子动力学和静态电子结构计算,研究了La₆₅X₃₅（X=Ni,Al）非晶合金体系原子结构随温度演化的规律及其相关电子结构特性.使用径向分布函数、Voronoi团簇以及键对分析等给出了从高温液体快速冷却到玻璃态过程中原子结构的演化规律.研究发现,该类合金体系的原子排布符合局域密堆模型,两体系中占比最大的特征多面体类型由溶质与溶剂原子半径比调控;两体系中高五次对称性局域结构随温度的下降而增加验证了其在抑制晶化方面的重要作用;利用投影态密度分析两体系电子结构之间的差异,指出La-5d与Ni-3d电子间强烈的杂化是La–Ni 间键长缩短的电子结构起源,为理解成分相关的结构和物性提供了重要线索.     

A Kilowatt Radio-Frequency Excited Diffusively Cooled All-Metal Slab Waveguide CO2 Laser

A new type of rf excited diffusively cooled all-metal slab waveguide CO2 laser is presented, in which the waveguide channel is constructed by two copper side walls and two copper electrodes, and the discharge is confined in the slab waveguide channel in terms of the voltage division structure. From this type of structure, over 1 kW laser power is obtained with an efficieney of more than 13%.     

Hole Spin Relaxation in an Ultrathin InAs Monolayer

We investigate the spin relaxation time of holes in an ultrathin neutral InAs monolayer （1.5 ML） and compare with that of electrons, using polarization-dependent time-resolved photoluminescence （TRPL） experiments. With excitation energies above the GaAs gap, we observe a rather slow relaxation of holes （τ1h = 196± 17 ps） that is in the magnitude similar to electrons （t1e= 354 ± 32 ps） in this ultrathin sample. The results are in good agreement with earlier theoretical prediction, and the phonon scattering due to spin-orbit coupling is realized to play a dominant role in the carrier spin kinetics.