Thermodynamic Properties and Thermodynamic Geometries of Black p-Branes

The heat capacity and the electric capacitance of the black p-branes(BPB) are generally defined,then they are calculated for some special processes.It is found that the Ruppeiner thermodynamic geometry of BPB is flat.Finally,we give some discussions for the flatness of the Ruppeiner thermodynamic geometry of BPB and some black holes.     

一种以压力一维均匀分布为特征的长条形对顶压砧

针对圆形端面平面对顶压砧装置中压力梯度大的问题, 本文设计了一种长条形端面的平面对顶压砧, 相应的封垫也改为长条形. 原理分析表明: 这种压砧可在沿长条形中心线的狭长区域内产生均匀分布的高压力. 本文采用长20 mm宽5 mm长条形端面的硬质合金压砧配合叶腊石封垫进行压力标定, 实验结果显示: 这种装置可产生10 GPa以上的高压, 在长条形中心线上至少12 mm长度范围内的不同位置上产生的压力基本一致, 在2.55 GPa压力时测量偏差小于2.0%, 在7.7 GPa时测量偏差小于3.6%. 这种特点很有利于对细长样品进行精确的高压物性测量.     

The characteristics of molten globule states and folding pathways strongly depend on the sequence of a protein

ABSTRACT

The majority of proteins perform their cellular function after folding into a specific and stable native structure. Additionally, for many proteins less compact ‘molten globule’ states have been observed. Current experimental observations show that the molten globule state can show varying degrees of compactness and solvent accessibility; the underlying molecular cause for this variation is not well understood. While the specificity of protein folding can be studied using protein lattice models, current design procedures for these models tend to generate sequences without molten globule-like behaviour. Here we alter the design process so the distance between the molten globule ensemble and the native structure can be steered; this allows us to design protein sequences with a wide range of folding pathways, and sequences with well-defined heat-induced molten globules. Simulating these sequences we find that (1) molten globule states are compact, but have less specific configurations compared to the folded state, (2) the nature of the molten globule state is highly sequence dependent, (3) both two-state and multi-state folding proteins may show heat-induced molten globule states, as observed in heat capacity curves. The varying nature of the molten globules and typical heat capacity curves associated with the transitions closely resemble experimental observations.     

非简谐振动和形变对ZnSe类石墨烯德拜温度热容量以及极性的影响

应用哈里森(Harrison)键联轨道法和固体物理理论和方法,考虑到原子的高阶非简谐振动,计算了ZnSe类石墨烯化合物的σ键和π键的极性、简谐系数和非简谐系数,得到它的德拜温度和定容热容量随温度变化的解析式以及形变引起的极性参量的改变量,探讨了形变对ZnSe类石墨烯极性的影响,并讨论了原子非简谐振动对化合物热力学性质的影响,结果表明:在300 K到1600 K温度区间内,简谐近似下,ZnSe的德拜温度为常量,热容量随着温度的升高呈非线性增大,其中温度较低时变化较快,温度较高时变化较慢并随着温度的升高而趋于常量.考虑到非简谐项后,德拜温度随着温度升高而增大,几乎为正比关系,而热容量的值比简谐近似的值有所减小,与第一非简谐项的影响相比,第二非简谐项的影响很小.形变对ZnSe类石墨烯的极性有重要的影响,在它的几种形变中,剪切形变对σ键的极性的影响最大,而键长形变对π键的极性的影响最小.温度愈高,非简谐效应愈显著.     

直流激励的大气压氩气喷枪的光谱研究

利用正高压驱动空心针-板喷枪装置,通入工作气体氩气,在大气压空气中产生了均匀稳定的喇叭状等离子体羽。电学和光学测量结果表明,放电虽然是在直流电源驱动下工作,但放电为周期性的脉冲。通过对等离子体羽发光信号进行空间分辨测量,研究了脉冲的形成机理,发现除针尖附近的电晕放电外,等离子体羽是以正流光(等离子体子弹)从针尖向着接地电极方向传播的。采用光谱学方法,对电子激发温度随电压的变化及其空间分布进行了测量。结果表明,电子激发温度(约为3 eV)随电压的增大而升高,在一定电压下,电子激发温度沿气流方向也在升高。     

A high‐accuracy complex‐phase method of simulating X‐ray propagation through a multi‐lens system

The propagation of X‐ray waves through an optical system consisting of many X‐ray refractive lenses is considered. For solving the problem for an electromagnetic wave, a finite‐difference method is applied. The error of simulation is analytically estimated and investigated. It was found that a very detailed difference grid is required for reliable and accurate calculations of the propagation of X‐ray waves through a multi‐lens system. The reasons for using a very detailed difference grid are investigated. It was shown that the wave phase becomes a function, very quickly increasing with increasing distance from the optical axis, after the wave has passed through the multi‐lens system. If the phase is a quickly increasing function of the coordinates perpendicular to the optical axis, then the electric field of the wave is a quickly oscillating function of these coordinates, and thus a very detailed difference grid becomes necessary to describe such a wavefield. To avoid this difficulty, an equation for the phase function is proposed as an alternative to the equation of the electric field. This allows reliable and accurate simulations to be carried out when using the multi‐lens system. An equation for the phase function is derived and used for accurate simulations. The numerical error of the suggested method is estimated. It is shown that the equation for the phase function allows efficient simulations to be fulfilled for the multi‐lens system.     

变频压缩机空调系统的理论分析及实验研究

变频空调器是由变频压缩机驱动的空调系统,压缩机通过变频调节其转速使压缩机单位时间内的排气量变化,从而达到调节制冷量的目的。本文提出了变频空调器制冷系统的原理和设计方法,具体给出了制冷量和压缩机频率的关系方程,并从理论和实验两方面对变频空调器制冷系统进行了分析,得到了频率曲线图,为变频空调器制冷系统的设计提供了依据。     

Adaptive Clipping for Neural Associative Memories

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第十五届全国原子与分子物理学术会议:大尺寸贵金属纳米团簇热力学性质的分子动力学模拟研究

采用分子动力学方法和原子嵌入模型势模拟了大尺寸金（n=1136--1556）、银（n=1088--1724）、铜（n=1000--1600）、铂（n=1004--1800）原子纳米团簇的熔化过程,得出了相应纳米团簇的势能随温度的变化曲线以及热容量随温度的变化曲线,研究了各种原子纳米团簇熔点与其团簇尺寸的关系。模拟结果表明团簇的熔点随团簇尺寸增大而升高,并逐渐向大块晶体靠拢。所有纳米团簇在熔化过程中在熔点附近都出现负热容现象,通过对团簇熔化前后结构的比较研,分析了导致这种现象的原因。