Total Electron Detachment and Induced Cationic Fragmentation Cross Sections for Superoxide Anion (O2−) Collisions with Benzene (C6H6) Molecules

In this study, novel experimental total electron detachment cross sections for O₂⁻ collisions with benzene molecules are reported for the impact energy range (10–1000 eV), as measured with a transmission beam apparatus. By analysing the positively charged species produced during the collision events, relative total ionisation cross sections were derived in the incident energy range of 160–900 eV. Relative partial ionisation cross sections for fragments with m/z ≤ 78 u were also given in this energy range. We also confirmed that heavier compounds (m/z > 78 u) formed for impact energies between 550 and 800 eV. In order to further our knowledge about the collision dynamics governing the fragmentation of such heavier molecular compounds, we performed molecular dynamics calculations within the framework of the Density Functional Theory (DFT). These results demonstrated that the fragmentation of these heavier compounds strongly supports the experimental evidence of m/z = 39–42, 50, 60 (u) cations formation, which contributed to the broad local maximum in the total ionisation observed from 550 to 800 eV. This work reveals the reactivity induced by molecular anions colliding with hydrocarbons at high energies, processes that can take place in the interstellar medium under various local conditions.     

基于Web的分子结构可视化系统的Java解决方案

针对医药、化学分子结构可视化研究、计算机辅助教学的需求,研究了利用Java技术开发基于Web的分子结构可视化系统的解决方案。论文介绍了系统的功能模块构成、系统的三层体系结构,并着重介绍了实现系统的关键技术,主要包括分子结构模型库设计与实现、平面模型显示及检索模块的设计与实现、真实感分子图形显示等。所开发的B／S结构的可视化系统,使得本地和远程用户可以在客户端对二维和三维分子结构进行检索和编辑,对具有数据库写权限的用户,还可以将新的分子结构添加入库。在该系统中,用户只能与中间层服务器通信,中间层服务器负责将各种请求转发给后台服务器,数据库对用户不可见,从而确保了数据安全性。本文所述系统的开发对于医药、化工方面的信息化和计算机辅助教学具有积极的意义,对类似信息系统的开发也有借鉴作用。     

盖子环替换及定点突变提高菜豆环氧化物水解酶对邻甲基苯基缩水甘油醚的催化性能

菜豆环氧化物水解酶1和2（PvEH1、PvEH2）能够动力学拆分外消旋邻甲基苯基缩水甘油醚（rac-oMGE）,从而保留(R)-oMGE。基于对PvEH1和PvEH2结构的同源模拟和分析,发现二者分子中的盖子环差异较大,故本文选择盖子环作为研究目标。经融合聚合酶链式反应（FPCR）,获得了PvEH2的盖子环区域被PvEH1对应区域替换的杂合酶Pv2Pv1。用全细胞酶E. coli/pv2pv1催化rac-oMGE,当(S)-oMGE刚好水解完全时,产物(S)-3-邻甲苯基-1,2-丙二醇（(S)-oTPD）的ee_p由PvEH2的58.3%提高至75.5%。为进一步提高酶的性质,在Pv2Pv1中选取11个氨基酸位点进行丙氨酸(A)突变,获得最优突变子E. coli/pv2pv1^K176A,活性为E. coli/pv2pv1（4.2U/g）的2.1倍,且当S构型的底物刚好完全水解时,(S)-oTPD的ee_p进一步提高为80.3%。分子对接分析发现,盖子环替换和K176位点突变为A,均使(R)-oMGE环氧环中的C_α更易受到酶中D101位点的攻击。利用E. coli/pv2pv1^K176A催化150mmol/L rac-oMGE水解制备(R)-oMGE（ee_s＞99%）和(S)-oTPD（ee_p=80.4%）,二者的产率Y_S和Y_P分别为32.7%和60.1%,时空产率STY_S和STY_P为1.6g/(L·h)和3.3g/(L·h)。本实验为改善EH的催化性质提供了一种有效策略。     

Integrating superstructure-based design of molecules,processes, and flowsheets

The key to many chemical and energy conversion processes is the choice of the right molecule, for example, used as working fluid. However, the choice of the molecule is inherently coupled to the choice of the right process flowsheet. In this work, we integrate superstructure-based flowsheet design into the design of processes and molecules. The thermodynamic properties of the molecule are modeled by the PC-SAFT equation of state. Computer-aided molecular design enables considering the molecular structure as degree of freedom in the process optimization. To consider the process flowsheet as additional degree of freedom, a superstructure of the process is used. The method results in the optimal molecule, process, and flowsheet. We demonstrate the method for the design of an organic Rankine cycle considering flowsheet options for regeneration, reheating, and turbine bleeding. The presented method provides a user-friendly tool to solve the integrated design problem of processes, molecules, and process flowsheets.     

基于功率型LED的在体整体荧光光学成像

用发光二极管（LED）替代常用的荧光激发光源汞灯,以实现基于LED的整体荧光光学成像（简称整体成像）。首先通过光谱计算分析,探讨了在不同波段与汞灯激发的荧光量相当时LED需要输出的光通量。以此为依据选择LED,构建了基于功率型LED的整体成像系统,用其动态监测绿色荧光蛋白（GFP）标记的肿瘤在裸鼠体内生长和药物治疗过程。实验表明,功率型LED可在类似于整体成像需要较大光功率的场合中应用。光源替代时,若两光源的光谱在选择的波段内分布不一样,则有必要考虑不同波长的光激发荧光效率差异的影响。     

原子力显微镜在生物分子间相互作用力的研究

近年来原子力显微镜在测量生物分子间的相互作用力方面取得显著的进步。本文综述原子力显微镜原理以及在生物分子间相互作用方面的研究,为人们理解分子的识别进程,提供一个新的研究方法。     

Single Molecule Studies on Dynamics in Liquid Crystals

Single molecule (SM) methods are able to resolve structure related dynamics of guest molecules in liquid crystals (LC). Highly diluted small dye molecules on the one hand explore structure formation and LC dynamics, on the other hand they report about a distortion caused by the guest molecules. The anisotropic structure of LC materials is used to retrieve specific conformation related properties of larger guest molecules like conjugated polymers. This in particular sheds light on organization mechanisms within biological cells, where large molecules are found in nematic LC surroundings. This review gives a short overview related to the application of highly sensitive SM detection schemes in LC.     

Synthesis of switchable amphipathic molecules triggered by CO2 through carbonyl‐amine condensation

Five long‐chain alkyl amidines were synthesized by condensation of N,N‐dimethylacetamide with octylamine, decylamine, dodecylamine, tetradecylamine, and hexadecylamine, respectively. Synthesis conditions including solvent, pH, temperature, and ratio of reactants were studied. The series of long‐chain alkyl amidine compounds reacted with dry ice to produce amidinium bicarbonates cationic amphipathic molecules. The critical micelle concentration (cmc) and surface tension at cmc (γ_cmc) measured by drop volume method show that these amphipathic molecules have excellent surface activity. The changes of cationic content measured by two‐phase titration and conductivity before and after bubbling CO₂, show different properties between amidines and amidinium bicarbonates cationic amphipathic molecules. The switchable function of the amidinium bicarbonate cationic amphipathic molecule in emulsification and demulsification was studied. Practical applications : Our innovative work is synthesizing switchable amphipathic molecules, N′‐alkyl‐N,N‐dimethylacetamidines, by carbonyl‐amine condensation. Compared with a former way of synthesis, our work shows great potential advantages in industrial application. Our synthesis route is simpler with higher yield and is carried out at ambient temperature. Moreover, the products are environmentally friendly. Compared with traditional amphipathic molecules, our products, N′‐alkyl‐N,N‐dimethylacetamidines, show good switchable properties, which can be switched on and off, trigged by CO₂.This means these products can be reused for several times, which is significant for environmental protection.     

高分子微孔精密过滤技术在化工生产中的应用

分析了液体精密过滤技术存在的问题,介绍了新型高分子微孔精密过滤技术的特点以及过滤工程的基本设计计算;通过工程实例,论述了精密澄清技术在合成氨净化系统的应用。     

非热等离子体催化转化C1分子及其催化剂研究进展

非热等离子体催化具有反应条件温和、启动快和反应器结构紧凑等特点,在C₁分子催化转化领域（如CO₂加氢、甲烷活化、水煤气变换反应和甲醇重整制氢）有着广阔的应用前景。具体来说,等离子体特有的高能电子可在气相中快速活化稳定性极强的C₁分子并生成活性物质,接着与催化剂结合发生表面化学反应,从而实现常温常压下C₁分子的高效转化。然而,等离子体与催化剂之间的协同作用机制以及催化机理极为复杂,仍有待进一步研究。本综述简单介绍了非热等离子体催化转化C₁分子的近期研究进展,重点探讨了适用于非热等离子 体的催化剂研究以及催化机理的高级原位表征。最后,提出了非热等离子体催化转化C₁分子的未来发展方向：①设计并构筑适用于非热等离子体催化的高效催化剂,并研究其构效关系;②发展高级原位表征技术,揭示活性物质的作用机理以及催化机理;③设计并构建高效的等离子体催化反应器,并建立反应器的理论模型和数值模拟方法,科学指导等离子体反应器的设计、优化和放大。