大液体量空分流程分析

针对有大液体量要求的冶金型空分装置,介绍了四种流程组织形式。通过模拟计算和分析比较,从设备投资、运行能耗、变负荷调节性、操作稳定性等方面,总结了不同流程型式的特点及适应性。针对不同的液体产品比例要求,推荐选择不同的流程形式,达到流程优化、节能降耗的目的。     

中学化学骨干教师PCK的实证研究*——以“析氢腐蚀和吸氧腐蚀”主题为例

使用本土化的教学内容表征(CoRe)工具调查了46名接受“国培计划”的中学化学骨干教师关于“析氢腐蚀和吸氧腐蚀”主题的PCK,结果表明:(1)骨干教师的PCK包含5个相互联系的组分,其中课程知识、学生知识以及策略知识均较为丰富。骨干教师能有针对性地选取化学学科专属的教学策略;(2)在教学取向方面,骨干教师在教学中发展与评价学生化学基本观念与学科核心素养的意识有待加强,引导学生自主建构学习的落实程度有待提高;(3)在评价知识方面,评价方式较为多元,但骨干教师对于形成性评价的重视程度不够。文末据此对我国化学教师教育以及化学PCK研究提出相关建议。     

Janus二维双层MoSSe/WSSe异质结光电性质的第一性原理研究

通过第一性原理计算研究了四种二维双层MoSSe/WSSe范德瓦耳斯异质结的光电性质。声子谱表明四种结构具有可靠的热力学稳定性。根据堆垛方式的不同，双层MoSSe/WSSe异质结可以是间接或直接半导体。而且，两种Janus型MoSSe/WSSe异质结具有1.22和1.88 eV的适中带隙、显著的可见光吸收系数、跨越了水氧化还原电位的带边位置。因此，Janus型的MoSSe/WSSe异质结构在光催化水分解领域具有一定的应用前景。     

High performance oscillator with 2-mW output power at 300 GHz

Material structures and device structures of a 100-GHz InP based transferred-electron device are designed in this paper. In order to successfully fabricate the Gunn devices operating at 100 GHz, the InP substrate was entirely removed by mechanical thinning and wet etching. The Gunn device was connected to a tripler link and a high RF(radio frequency)output with power of 2 mW working at 300 GHz was obtained, which is high enough for applications in current military electronic systems.     

不同中心波长飞秒脉冲激发InAs表面辐射太赫兹波的机理研究

研究了p型(100)InAs在不同中心波长飞秒激发光(750—850nm)作用下的太赫兹(THz)波辐射特性.这种太赫兹辐射的光谱性质与光学Dember效应密切相关，飞秒脉冲激发下产生的载流子在InAs表面的Dember场内做加速运动，从而辐射出THz电磁波.实验结果表明：不同中心波长的激发光作用下，InAs表面产生的Dember电场、光生载流子浓度、谷间散射效应以及处于不同状态的载流子数目都发生了变化，因而激发出太赫兹波的功率、振幅、频谱分布和有效谱宽是不同的.这项研究将有利于THz时域光谱技术以及实验     

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.     

新题征展(69)

A 题组新编 1.已知ABCD为空间四边形,分别求下列情况下两对角线AC、BD所成的角: