Analysis of Non-innocence of Phosphaquinodimethane Ligands when Charge and Aromaticity Come into Play

Several phosphaquinodimethanes and their M(CO)₅ complexes (M=Cr, Mo, W) and model derivatives have been theoretically investigated regarding the quest of non-innocence. Computed structural and electronic properties of the P-Me/NH₂ substituted phosphaquinodimethanes and tungsten complexes revealed an interesting non-innocent ligand behaviour for the radical anion complexes with distonic ion character and a strong rearomatization of the middle phenyl ring. The latter was further probed taking also geometric aromaticity (HOMA) and quinoid distortion parameters (HOMQc) into account, as well as NICS(1). Furthermore, the effect of the P-substitution was investigated for real (or plausible) complexes and their free ligands focusing on the resulting aromaticity at the middle phenyl ring and vertical one-electron redox processes. The best picture of ligand engagement in redox changes was provided by representing NICS(1) values versus HOMA and the new geometric distortion parameter HOMQc8.     

空间遥感测绘光学系统研究综述

将遥感技术应用到测绘当中是现代地质测绘技术的发展趋势,随着光学载荷分辨率的不断提高,遥感测绘已经成为社会发展和国民经济发展的重要保障。光学载荷决定了测绘空间遥感器的分辨率、测绘精度、卫星平台体积与重量,是遥感器的核心部分。本文对高成像质量透射光学系统、同轴三反光学系统、离轴三反系统等常用的空间遥感测绘光学系统的结构形式和光学性能分别进行了介绍,并对处于研发阶段的新型空间反射光学系统的结构形式和光学性能进行了展望。分析认为,根据不同的应用环境和技术指标,合理选用不同种类的遥感测绘光学系统,可以最大程度利用平台资源,满足遥感测绘需求。     

High Compression‐Induced Conductivity in a Layered Cu–Br Perovskite

We show that the onset pressure for appreciable conductivity in layered copper‐halide perovskites can decrease by ca. 50 GPa upon replacement of Cl with Br. Layered Cu–Cl perovskites require pressures >50 GPa to show a conductivity of 10^?4 S cm^?1, whereas here a Cu–Br congener, (EA)₂CuBr₄ (EA=ethylammonium), exhibits conductivity as high as 2×10^?3 S cm^?1 at only 2.6 GPa, and 0.17 S cm^?1 at 59 GPa. Substitution of higher‐energy Br 4p for Cl 3p orbitals lowers the charge‐transfer band gap of the perovskite by 0.9 eV. This 1.7 eV band gap decreases to 0.3 eV at 65 GPa. High‐pressure X‐ray diffraction, optical absorption, and transport measurements, and density functional theory calculations allow us to track compression‐induced structural and electronic changes. The notable enhancement of the Br perovskite's electronic response to pressure may be attributed to more diffuse Br valence orbitals relative to Cl orbitals. This work brings the compression‐induced conductivity of Cu‐halide perovskites to more technologically accessible pressures.     

五阶势MKdV方程的一个不变性

§1Introduction Asweknow,Backlundtransformation[1-3]isaverypowerfulwayforfindingnonline evolutionequations.Inrecentdecades,Painlevéanalysis[4]hasbecomeaverypopu methodtoobtainBacklundtransformation.Inreference[5],fordevelopingthetheory Painlevéanalysis,AndrewPickeringintroduceanewexpansionvariableZwhichsatisf thefollowingRicattiSystem:Zx=1-AZ-BZ2,Zt=-C+(AC+Cx)Z-(D-BC)Z2.(1.Astheapplicationofthenewexpansionvaraible,thepotentialfifth-orderMKd equation(PMKdV5)-vxt+(vxxxxx-10k2v2…     

有限深水域中三维频域自由面格林函数及其导数的计算方法

三维频域自由面格林函数及其偏导数的数值计算是海洋结构物水动力分析的难点.本文对有限水深格林函数及其偏导数的数值算法作出两点改进:①对原函数的级数表达式进行变形,提出适用于数值计算的形式,解决高频率情况下级数解的计算失真问题;②对Gauss-Laguerre积分法作出改进,解决高频率大水深情况下积分解的数值溢出问题.计算...     

厚胶光刻非线性畸变的校正

利用厚胶光刻技术制作大深度微结构元件是一种有效的途径,但厚胶光刻过程中的非线性畸变对光刻面形质量的严重影响限制了该技术的应用,基于此,提出了一种对掩模透射率函数进行校正的方法。分析空间像形成及其在光刻胶内传递、曝光、显影等过程中非线性因素的影响,利用模拟退火算法对掩模透射率函数进行校正,以提高光刻面形质量,并以凹面柱透镜为例,给出了校正前后的显影轮廓模拟结果,其校正后浮雕面形的体积偏差仅为2.63%。该方法在有效改善面形质量的同时,并没有引起掩模的设计、制作难度及费用增加,这对于设计、制作高质量的微结构元件有重要意义。     

单极型马赫-曾德尔调制器的互调失真分析

针对单极型马赫曾德尔电光调制器在Radio over Fiber(RoF)和副载波复用系统中的应用,讨论了输入两路射频信号的情形,给出了电光调制器互调失真的严格通用解析解。该解析解可用于表示任意阶的互调失真项和谐波项。数值结果表明了该解析解的正确性。分析结果表明,调制器的三阶互调失真与调制器偏置相移无关,只与输入射频信号的调制系数有关,并且当外加偏置电压等于调制器的半波电压时,只存在偶数阶的失真项。根据该解析解,可方便地设计模拟光通信系统,精确地预计外调制器的非线性特征,优化系统性能。     

Gauge functions and Galilean invariance of Lagrangians

A novel method to make Lagrangians Galilean invariant is developed. The method, based on null Lagrangians and their gauge functions, is used to demonstrate the Galilean invariance of the Lagrangian for Newton's law of inertia. It is suggested that this new solution of an old physics problem may have implications and potential applications to all gauge-based theories of physics.     

高精度半导体激光打标机F-θ镜头设计

为保证半导体激光打标机F-θ镜头的扫描质量,实现系统像高与扫描角的线性变化,需对F-θ镜头给予一定的畸变量,并使其满足等晕条件。分析F-θ镜头工作原理及像差要求,根据1 064 nm半导体激光打标机的光源成像要求选择合适的玻璃材料,合理分配每片透镜的光焦度,以保证等晕成像;根据F-θ镜头线性成像要求,计算系统总畸变量为1.6%,系统总畸变量为系统的实际桶形畸变与相对畸变量之和;在光学系统优化设计时,引入这两项优化参数,优化过程中观察系统成像变化情况。设计结果表明:系统MTF曲线接近衍射极限,F-θ镜头相对畸变小于0.36%,各视场均方根半径均小于艾里斑直径,并且整个系统70%的能量集中在直径为16 μm的圆内,系统总畸变量为1.58%,满足设计指标要求。     

Effects on the evolution of microstructure and properties of low-silicon cast aluminum alloys in service

ABSTRACT

The microstructure evolution and property change of four kinds of low silicon cast aluminum alloy exposed to heat for 0–50?h at 200°C were studied by means of Brinell hardness test, tensile property test, friction and wear property test and XRD analysis. The results show that with increasing thermal exposure time, the tensile strength of each group of samples decreased and the amount of wear increased. The tensile strength of samples with more Si content decreased slowly. When the time increased to 50?h, the increase of wear loss was the largest. The hardness of samples after thermal exposure increases compared with that before thermal exposure. The residual stress of (311) diffraction crystal surface of AlSi3.5Mg0.66 under different thermal exposure time was measured. The type of residual stress changed from residual tensile stress to residual compressive stress after thermal exposure. There is an abnormal phenomenon that the hardness of the sample increased and the amount of wear increased, and it is evident that the distribution of residual stress was inhomogeneous after thermal exposure. It is found that with increasing thermal exposure time to 50?h, the average lattice distortion ε of the low-index crystal plane and the high-index crystal plane in the aluminum alloys gradually increased.