波瓣波导谐振腔太赫兹回旋管的研究

以电子回旋脉塞非线性理论为基础, 结合三维电磁仿真软件, 通过导入高频场数值解替代理论解析的方法, 对波瓣波导谐振腔高次谐波太赫兹回旋管进行了理论和模拟研究. 给出了该类回旋管的起振电流、耦合系数以及注波互作用效率等重要参数, 并在此基础上设计了一只工作频率为0.4 THz, 工作模式TE₃₃模三次谐波波瓣波导谐振腔回旋管, 其电子注参数为1.0 A, 40.5 kV, 横纵速度比1.5,互作用区引导磁场为5.09 T, 输出功率达到3.3 kW.     

A Compton scattering image reconstruction algorithm based on total variation minimization

Compton scattering imaging is a novel radiation imaging method using scattered photons.Its main characteristics are detectors that do not have to be on the opposite side of the source,so avoiding the rotation process.The reconstruction problem of Compton scattering imaging is the inverse problem to solve electron densities from nonlinear equations,which is ill-posed.This means the solution exhibits instability and sensitivity to noise or erroneous measurements.Using the theory for reconstruction of sparse images,a reconstruction algorithm based on total variation minimization is proposed.The reconstruction problem is described as an optimization problem with nonlinear data-consistency constraint.The simulated results show that the proposed algorithm could reduce reconstruction error and improve image quality,especially when there are not enough measurements.     

Low temperature testing and neutron irradiation of a swept charge device on board the HXMT satellite

We present the low temperature testing of an SCD detector, investigating its performance such as readout noise, energy resolution at 5.9 keV and dark current. The SCD's performance is closely related to temperature, and the temperature range of -80 ℃ to -50 ℃ is the best choice, where the FWHM at 5.9 keV is about 130 eV. The influence of the neutron irradiation from an electrostatic accelerator with fluence up to 1×10⁹ cm^-2 has been examined. We find the SCD is not vulnerable to neutron irradiation. The detailed operations of the SCD and the test results of low temperature are reported, and the results of neutron irradiation are discussed.     

电磁感应双光子带隙的产生和控制

基于电磁感应透明技术, 通过求解原子的密度矩阵方程和电磁场的传输矩阵方程, 研究了被行波场和驻波场共同耦合的一个四能级冷原子介质的稳态光学特性, 发现在特定参数下能够产生一个几乎完美的双光子带隙结构, 在这两个光子带隙对应的频率区域内反射率都均匀地超过95%. 通过改变耦合场的强度和频率, 可以方便地调节这两个光子带隙的位置和宽度. 这一双光子带隙结构可用来实现全光路由和全光开关, 有望在全光信息网络中获得应用.     

热损伤奥克托金(HMX) 缺陷的X射线小角散射研究

奥克托金(HMX) 在温度作用下, 会发生热膨胀、 相转变、 热分解等物理、 化学变化, 导致在材料内部产生大量缺陷, 进而会对其宏观性能造成明显影响. 为了深入了解热损伤HMX内部的缺陷演化, 本文采用X射线小角散射和原子力显微技术研究了热损伤HMX的内部缺陷. 结果发现HMX在180 °C相变过程中散射曲线有明显的变化, 颗粒内部生成了大量10nm左右的孔洞, 随着加载时间延长, 其尺寸增大到25nm, 数量明显降低. 当HMX在190 °C、 200 °C保温5h时, 由于HMX热分解内部有新缺陷生成, 小角散射发现其尺寸约为5至8nm, 随着加载温度升高, 其数量增加.     

Orbital-decomposed electronic and magnetic properties of the double perovskite Sr2FeReO6

The detailed orbital-decomposed electronic structures and magnetic properties of the double perovskite Sr₂FeReO₆ have been studied using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA). Both occupied and unoccupied s and three p states of Fe³⁺ ion are located far away from the Fermi level, while all up-spin states and most down-spin states are completely filled for the s and three p states of Re⁵⁺ ion. The octahedral crystal field of the oxygen atoms around transition-metal (TM) sites splits the five-fold degenerate d states of the free TM atoms into triply degenerate t_2g states with smaller bonding-antibonding splitting and doubly degenerate e_g states with larger bonding-antibonding splitting. The Fe³⁺ and Re⁵⁺ ions are in the states (3d⁵, S=5/2) and (5d², S=1) with magnetic moments 3.70 and −0.86μ_B, respectively and thus antiferromagnetic coupling via oxygen between them. There are no direct interactions between two nearest Fe-Fe or Re-Re pairs, whereas along each Fe-O-Re-O-Fe or Re-O-Fe-O-Re chains, the hybridizations between Fe 3d and 4s, O 2s and 2p, as well as Re 5p, 5d and 6s orbitals are fairly significant.     

A New Rhodamine-Based “Off-On” Fluorescent Chemosensor for Hg (II) Ion and its Application in Imaging Hg (II) in Living Cells

A novel rhodamine derivative (Rh-C), synthesized by the reaction of rhodamine ethylenediamine and cinnamoyl chloride, was evaluated as a chemoselective Hg(2+) ion sensor. Addition of Hg(2+) to an ethanol aqueous solution of the Rh-C resulted in a color change from colorless to obvious pink color together with distinctive changes in UV-vis absorption spectrum and fluorescence spectrum. However, other common alkali-, alkaline earth-, transition- and rare earth metal ions induced no or minimal spectral changes. The interaction of Hg(2+) and sensor Rh-C was proven to adopt a 1:1 binding stoichiometry and the recognition process is reversible. The chemosensor displayed a linear response to Hg(2+) in the range of 0.4-5?μM with a detection limit of 7.4?×?10(-8)?M. The sensor Rh-C was also successfully applied to the imaging of Hg(2+) in HL-7702 cells.     

Cu(L-His)2溶液配位结构的X射线吸收精细结构分析

采用X射线吸收精细结构分析(XAFS)方法分析Cu(His)₂复合物的配位模式,通过测定不同pH值下的铜的K边XAFS吸收谱,研究Cu(His)₂第一配位壳层的结构．为了更准确地验证Cu(His)₂配位结构,对组氨酸的羧基和咪唑分别进行了化学修饰．研究结果明确了在不同pH环境下组氨酸的羧基、氨基和咪唑的配位情况．对于争议最大的在生理pH值下组氨酸的配位方式,其结果更支持六配位模式,同时可能有少量的五配位模式配合物平衡存在.     

Young＇s modulus surface and Poisson＇s ratio curve for tetragonal crystals

This paper gives the general expressions for the compliance s′ijkl, Young＇s modulus E（hkl） and Poisson＇s ratio v（hkl, θ） along arbitrary loading direction [hkl] for tetragonal crystals. The representation surface for which the length of the radius vector in the [hkl] direction equals E（hkl） and representation curve for which the length of the radius vector with angle θ deviated from the reference directions [001^-], [100], [001^-], [101^-] and [112^-] equals v（100, θ）, v（001, θ）, v（110,θ）, v（101,θ） and v（111, θ） respectively, are constructed for nine tetragonal crystals （ammonium dihydrogen arsenate, ammonium dihydrogen phosphate, barium titanate, indium, nickel sulfate, potassium dihydrogen arsenate, potassium dihydrogen phosphate, tin and zircon）. The characteristics of them are analysed in detail.     

荧光猝灭法对肉桂酸与人血清白蛋白间的相互作用的研究

白蛋白是血液循环系统中最丰富的一种蛋白质,能与许多物质结合,并起着运输蛋白的作用。文章利用荧光光谱法研究了中药有效成分肉桂酸与人血清蛋白间的非共价结合特性。研究表明,在pH7.4作用液、286nm激发波长条件下,肉桂酸对人血清白蛋白的荧光发射有较强猝灭作用。当作用温度为37和47℃时,肉桂酸与人血清蛋白间的结合常数K分别为1.2767×103和3.4041×103L.mol-1,结合位点数n分别为0.7586和0.8356,表明温度升高有利于两者的结合;同时,根据不同作用温度时非共价结合复合物的热力学参数变化,证明肉桂酸与人血清白蛋白分子间的结合力主要是疏水作用。研究结果为进一步研究肉桂酸的药理作用,尤其是对血浆蛋白构像的影响提供了重要信息。