Absolute small-angle measurement based on optical feedback interferometry

We present a simple but effective method for small-angle measurement based on optical feedback interferometry （or laser self-mixing interferometry）. The absolute zero angle can be defined at the biggest fringe amplitude point, so this method can also achieve absolute angle measurement. In order to verify the method, we construct an angle measurement system. The Fourier-transform method is used to analysis the interference signal. Rotation angles are experimentally measured with a resolution of 10^-6 rad and a measurement range of approximately from -0.0007 to ＋0.0007 rad.     

Six-Fold Degenerate Dark States in a Four-Level Atomic System

With all driving fields on Raman resonance, a tripod-type atomic system quickly evolves into a dark state decoupled from the lossy excited level. The dark state depends strongly on field Rabi frequencies, spontaneous decay rates, and the initial atomic population in a complicated way. Analytical results reveal that it is a sixfold degenerate dark state with its three components superposed both coherently and incoherently due to population redistribution from spontaneous emission.     

蚕豆16Sr RNA基因的一级结构分析

蚕豆叶绿体DNA属无反向重复顺序类型,这种类型的16s rRNA基因的一级结构本文属首次报道。我们采用了洪国藩的非随机DNA顺序测定法,测出蚕豆叶绿体16s rRNA基因金长为1491bp。通过比较及遗传距离图的构建表明蚕豆16SrRNA基因的变化速率比具有反向重复顺序类型的烟草、油菜及玉米的要快,说明反向重复顺序具有降低反向重复顺序内的DNA变化速率的功能。同时我们的结果也支持了Kolodner等人关于反向重复顺序能重组交换进行异源修复的推测。     

水稻组蛋白H3基因和1.5-二磷酸核酮糖羧化酶/加氧酶小亚基基因的克隆和结构分析

本文从水稻(Oryza sativa,IR26)细胞核中分离出的几个基因,测定了它们的DNA核苷酸序列,并从水稻IR26基因组文库中筛选和分离到一个14.8kb的DNA片段,其中含有一个H3基因和另一个类似H3的假基因。DNA序列分析的结果表明:水稻H3基因的编码顺序有405bp长,其5′和3′端的非编码区则含有几个与一般真核基因或组蛋白基因共同的调控序列。水稻H3基因的密码子有一显著特点,密码子的第三个核苷酸98％为G和C,通过Southern转移分析,表明水稻二倍体基因组中大约有50个左右H3基因,从同一个水稻基因文库中,我们还分离鉴定到了rbcS基因,它编码1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco)的小亚基,水稻rbcS基因的顺序含有一个内含子,其位置与小麦的相同,水稻和小麦rbcS基因所编码的转移肽,其最初18个氨基酸彼此是相同的。     

离子声孤子在不均匀等离子体中的传播特性

本文考虑了离子的有限温度和离子与中性分子的碰撞,讨论离子声孤子在电离导致的弱不均匀等离子体中的传播特性,得到自洽的非均匀浓度分布N(x),漂移速度分布V(x)和相应的孤子解,数值计算给出孤子幅度、速度、宽度随位置的变化,所得结果合理并与实验相符。 关键词：     

剪切形变下掺杂及缺陷对MoS2电子结构的影响

本文利用密度泛函理论,研究剪切形变下掺杂改性及不同类型缺陷对MoS2电子结构的影响。发现：剪切形变下,MoS2+P体系为相对最稳定的结构,掺杂改性相较于缺陷对模型稳定性影响更小;模型MoS2+P+Se中P-Mo键易形成共价键,而其中的Se-Mo键和MoS2+P-Mo-S模型中的P-Mo键,易形成离子键;掺杂使MoS2模型能隙变大,而缺陷使能隙减小,且S和Mo原子共缺陷的模型带隙为0;缺陷相较于掺杂改性模型,更能使Mo原子周围增加电荷聚集度,带隙值更低,更能影响或调控模型的电子结构。     

Electronic and optical properties of 3N-doped graphdiyne/MoS2 heterostructures tuned by biaxial strain and external electric field

The construction of van der Waals (vdW) heterostructures by stacking different two-dimensional layered materials have been recognised as an effective strategy to obtain the desired properties. The 3N-doped graphdiyne (N-GY) has been successfully synthesized in the laboratory. It could be assembled into a supercapacitor and can be used for tensile energy storage. However, the flat band and wide forbidden bands could hinder its application of N-GY layer in optoelectronic and nanoelectronic devices. In order to extend the application of N-GY layer in electronic devices, MoS₂ was selected to construct an N-GY/MoS₂ heterostructure due to its good electronic and optical properties. The N-GY/MoS₂ heterostructure has an optical absorption range from the visible to ultraviolet with a absorption coefficient of 10⁵ cm^-1. The N-GY/MoS₂ heterostructure exhibits a type-Ⅱ band alignment allows the electron-hole to be located on N-GY and MoS₂ respectively, which can further reduce the electron-hole complexation to increase exciton lifetime. The power conversion efficiency of N-GY/MoS₂ heterostructure is up to 17.77%, indicating it is a promising candidate material for solar cells. In addition, the external electric field and biaxial strain could effectively tune the electronic structure. Our results provide a theoretical support for the design and application of N-GY/MoS₂ vdW heterostructures in semiconductor sensors and photovoltaic devices.     

高分子分散剂在陶瓷浓悬浮体制备中的应用

良好分散的陶瓷浓悬浮体是胶态成型实现的前提和关键。本文阐述了高分子分散剂的分散稳定作用及其在多种单相复相陶瓷浓悬浮体制备中的研究和应用,进而从高分子分散剂自身特性,陶瓷分散相和分散介质的物理化学性质以及陶瓷胶态成型工艺操作等方面,分析了各因素对高分子分散剂分散效果的影响,最后指出了能够优化陶瓷浓悬浮体性能的高分子分散剂的研究趋势。