环己烷催化氧化制取顺酐和醋酸的催化剂研究

为研究气态环己烷催化氧化制取顺酐及醋酸的新反应，采取不同的方法制备了系列固体VPO催化剂.借助XRD、FT-IR对催化剂进行了主体晶相确定，用氧化还原滴定方法测定了不同晶相催化剂中钒的平均氧化数.结合催化反应的活性评价，发现催化剂主体晶相、结晶度、活化气氛和催化剂的V4＋/V5＋比均对目标反应的催化活性产生影响，5种催化剂中以(VO)2P2O7晶相催化剂的活性为最高.     

Quantum transport in topological semimetals under magnetic fields (II)

Research about two-dimensional (2D) materials is growing exponentially across various scientific and engineering disciplines due to the wealth of unusual physical phenomena that occur when charge transport is confined to a plane. The applications of 2D materials are highly affected by the electrical properties of these materials, including current distribution, surface potential, dielectric response, conductivity, permittivity, and piezoelectric response. Hence, it is very crucial to characterize these properties at the nanoscale. The Atomic Force Microscopy (AFM)-based techniques are powerful tools that can simultaneously characterize morphology and electrical properties of 2D materials with high spatial resolution, thus being more and more extensively used in this research field. Here, the principles of these AFM techniques are reviewed in detail. After that, their representative applications are further demonstrated in the local characterization of various 2D materials’ electrical properties.

     

Phytochemical,cytotoxic and chemotaxonomic study on Ajuga forrestii Diels (Labiatae)

A phytochemical investigation of Ajuga forrestii Diels led to the isolation of 14 compounds, including eight neo-clerodane diterpenes (1–8), two phytoecdysteroids (9, 11), one stigmastane sterol (10) and three iridoid glycosides (12–14). The structures of these compounds were identified by spectroscopic methods and a comparison of their data with those reported in the literature. This is the first report of compounds 1–14 from A. forrestii. The cytotoxic activities of the aqueous extract of A. forrestii and several compounds have been studied and the chemotaxonomic significance of isolated compounds has also been summarised.     

Micro-FTIR study on structure of macerals from Jurassic coals in Northwestern China

Jurassic coal in Northwest China is rich in resources and it is a necessary premise to reveal the chemical structure characteristics of the coal macerals in this region before the coal is put into reasonable and efficient use. Micro-FTIR technique was used to investigate the chemical composition and structures of vitrinite semifusinite and fusinite from Jurassic coal in Northwestern China. The results show that vitrinite and semifusinite have more aliphatic hydrogen, but fusinite has more aromatic hydrogen and C=O structure. The aliphatic hydrogen in semifusinite is higher than that in fusinite and it is this structure characteristic of semifusinite that led to the richer inertinite but higher reactivity of the Northwestern China coal. Not only vitrinite but also semifusinite and fusinite with weaker reducibility have less aliphatic hydrogen and more C=O structures than those with stronger reducibility. The different intensity of oxidation in the process of coalification is one of the causes that led to different type of reducibility.     

Data Acquisition and Transfer System for In-situ Atomic Emission Spectroscopic Analysis

A new method of data acquisition,proceeding and data share is introduced and a data acquisition and transfer system targeting in-situ spectroscopic analysis in metallurgy is established. This system is designed for the critical control of steelmaking, which greatly requires rapid and suitable information feedback. The information includes analysis data, measurement data and controls. The analysis data are acquired from the serial port of the computer-aided spectrometers or other devices and are identified, converted and then stored to the standard database in a network server. The network is based on the Intranet structure and works on the Windows NT operation system. It supports remote access and Internet connection so that the analysis data can be shared,proceeded and developed by certified personnel throughout the network. A set of specially designed data transfer devices with display panel are used in the severe places to display real-time analysis data and other information, which are offered from the nearest workstation on the network. These devices are dust-proofed and anti-magnetic. Each device offers up to 30 terminals with the limited distance of 3000 meters at 2400 baud-rates under the industrial condition. The application program for the data proceeding is integrated to the system. It includes system security, data acquisition, data transfer, data process and display. It also includes auxiliary functions such as operation help, system's resources monitoring and other customer-defined parameters. The software's functions directly related to the system are detailed discussed. Associated with another management and control software programmed for this system,the critical control of steelmaking can be approached.     

应用型本科院校物理化学考核模式的构建与实践

针对应用型本科院校现有的物理化学课程考核模式存在的问题,采取过程化考核和终结性考核相结合的方式,构建了新的物理化学考核模式,并在教学中进行了实践。实践表明:通过考核模式改革,化学专业学生物理化学成绩相对其他不同专业或相同专业不同年级的学生而言,物理化学课程成绩产生了显著性差异,且明显提高;激发了学生的学习兴趣,调动了学生学习的积极性、主动性,提升了学生专业素养。     

VPO催化剂上气态环己烷催化氧化制取顺酐及醋酸的研究

为研究气态环己烷催化氧化制取顺酐及醋酸的新反应，采用沉淀法制备了8种相同晶相的VPO固体催化剂．借助XRD、FT-IR技术对催化剂进行主体晶相确定，利用氧化还原滴定方法测定了催化剂中钒的平均氧化数．结合催化反应的活性评价，发现具有适宜结晶度、适宜V^4 ／V^5 比和在反应气氛下活化的催化剂，均可提高实现目标反应的催化活性；添加钼组份并不能改善催化剂的选择性．     

Constraints on the generalized natural inflation after Planck 2018

Based on the dynamics of single scalar field slow-roll inflation and the theory of reheating, we investigate the generalized natural inflationary (GNI) model. We introduce constraints on the scalar spectral index \begin{document}$n_{s}$\end{document} and the tensor-to scalar ratio r for the \begin{document}$\Lambda$\end{document}CDM \begin{document}$+r$\end{document} model, according to the latest data from Planck 2018 TT, TE, EE+low E+lensing (P18) and BICEP2/Keck 2015 season (BK15), i.e., with \begin{document}$n_{s}=0.9659\pm0.0044$\end{document} at 68% confidence level (CL), and \begin{document}$r<0.0623$\end{document} at 95% CL. We find that the GNI model is favored by P18 and BK15 in the ranges \begin{document}$\log_{10}(f/M_{p})= 0.62^{+0.17}_{-0.18}$\end{document} and \begin{document}$m=0.35^{+0.13}_{-0.23}$\end{document} at 68% CL. In addition, the corresponding predictions of generalized and two-phase reheating are discussed. It follows that the parameter m has significant effect on the model behavior.     

煤及其显微组分热解过程中的半焦收缩动力学

采用显微热台对煤显微组分微粒进行热解, 通过在线拍摄的显微图片能够直观揭示出煤粒热解时呈现的两个阶段——脱挥发分和半焦收缩. 通过对显微图片的图像分析, 获得了煤粒面积随温度变化的热解曲线. 结果表明, 半焦收缩过程由缓慢收缩、过渡收缩和快速收缩三个阶段构成, 活化能、指前因子及速率常数皆随三个阶段依次增大, 其原因在于各段的化学键断裂种类及其键能、生成的自由基碎片及缩聚反应存在不同特点. 就半焦收缩而言, 镜质组的速率常数大于惰质组; 变质程度较低的神东煤及其显微组分的速率常数大于平朔煤及其对应显微组分,即前者显示出较强的半焦收缩反应性.     

磁场中拓扑物态的量子输运

拓扑物态包括拓扑绝缘体、拓扑半金属以及拓扑超导体.拓扑物态奇异的能带结构以及受拓扑保护的新奇表面态,使其具有了独特的输运性质.拓扑半金属作为物质的一种三维拓扑态具有无能隙的准粒子激发,根据导带和价带的接触类型分为外尔半金属、狄拉克半金属和节线半金属.本文以拓扑半金属为主回顾了在磁场下拓扑物态中量子输运的最新工作,在不同...