燃烧反应机理构建的极小反应网络方法——氢氧燃烧

基于化学同时平衡原理,提出复杂反应体系的极小反应网络方法(MRN),在指定中间物种数目条件下,构建反应步数最小的详细燃烧反应机理.确定了8个物种的氢氧燃烧的6个独立反应,对缺乏动力学参数的独立反应进行组合替代,反应速率常数采用Arrhenius双参数形式.采用构建的9步反应氢氧燃烧机理(MRN-C0)进行了点火延迟时间和层流火焰速度的模拟.     

Synthesis and characterisation of benzoxazole-based liquid crystals possessing 3,5-difluorophenyl unit

Series of fluorinated compounds, 2-(3′,5′-difluoro-4′-alkoxybiphenyl-4-yl)-benzoxazole derivatives (nFBx), were prepared and characterised. Their phase transition behaviour was investigated by differential scanning calorimetry and polarising optical microscopy. In the case of carbon atoms in the alkoxy chain between 4 and 10, they exhibited enantiotropic mesophases with the mesophase ranges of 12–119°C and 23–152°C on heating and cooling for compounds bearing different substituents (H, CH₃, Cl, and NO₂). With the exception of nitro-substituted compounds, the nFBx series displayed intense photoluminescence emission at 380–385 nm in methylene chloride solution when they were excited at their absorption maxima. Compared to non-fluorinated analogues, fluorinated compounds nFBx (apart from nitro-substituted compounds) exhibited much lower melting points, but comparable or slightly narrower mesophase ranges during both heating and cooling, which were attributed to the disruption of the side-to-side intermolecular packing caused by the two lateral fluoro substituents.     

具有药理活性多糖的研究现况

本文介绍具有药理活性的多糖以及多糖的分离提取和结构分析方法的情况，引用参考文献３４篇。     

Simultaneous determination of catechins, caffeine and gallic acids in green, Oolong, black and pu-erh teas using HPLC with a photodiode array detector

A simple and fast HPLC method using a photodiode array detector was developed for simultaneous determination of four major catechins, gallic acid and caffeine. After multiple extractions with aqueous methanol and acidic methanol solutions, tea extract was separated within 20 min using a methanol-acetate-water buffer gradient elution system on a C(18) column. The sample extraction data demonstrated that the single extraction used in the previous studies with aqueous acetonitrile or methanol is not sufficient; the multiple extraction procedure is essential for the quantitative analysis of catechins, phenolic acids and caffeine in teas. Several green, Oolong, black and pu-erh teas were successfully analyzed by this method. The analytical results obtained indicated that green teas contain higher content of catechins [(-)-epigallocatechin gallate, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epicatechin] than both Oolong, pu-erh and black teas because fermentation process during the tea manufacturing reduced the levels of catechins significantly. The fermentation process also remarkably elevated the levels of gallic acid in full-fermented pu-erh and black teas. Another interesting finding is the low level of caffeine in Oolong teas, especially in Fujian Oolong tea.     

城市土壤对铅和锌的吸附热力学特征

采用批量法对温州景山森林公园5种不同城市土壤对Pb和Zn的吸附热力学行为进行了研究。结果表明,吸附等温线符合Freundlich等温式和Temkin等温式,相关系数都在0．85以上,5种土壤对Ph的吸附强度由高到低的次序为C,E,B,A,D,对Zn的吸附强度由高到低的次序为C,E,D,B,A。     

氟对PtSnNaLa/ZSM-5催化剂丙烷脱氢反应性能的影响

在PtSnNaLa/ZSM-5催化剂中引入氟元素,制得用于丙烷脱氢反应的氟改性催化剂,利用X射线衍射(XRD)、NH₃吸脱附(NH₃-TPD)、红外(FT-IR) 、固体核磁(²⁷Al MAS NMR)和程序升温还原(H₂-TPR)等技术手段研究不同氟含量对催化剂的结构、表面酸性和丙烷脱氢反应性能的影响。 结果表明,氟能降低催化剂表面的弱酸强度,增强Pt与载体间的相互作用力,降低反应副产物的选择性,从而提高了产物丙烯的选择性,当氟的添加量为0.2%时,丙烯选择性可达到99.2%。 同时氟的加入易于载体骨架的脱铝,使得Sn组分的还原变得相对容易,但对催化剂结构没有明显的影响。     

DNA Binding Properties and Cytotoxic Activities of Two Trinuclear Ruthenium（Ⅱ） Polypyridyl Complexes

The interactions between two trinuclear Ru（II） complexes and calf thymus DNA（CT DNA） were studied via absorption spectroscopy, reverse salt titrations, binding stoichiometry, DNA melting experiments, as well as viscosity measurement. The results indicate that complexes 1 and 2 bind to DNA via the interaction of the planar π-delocalized system of the complexes with intrinsic binding constants of 4.18 × 10^5 and 3.85 × 10^6 L/tool, respectively, and non-electrostatic binding free energy makes a predominant contribution to the binding free energy. The in vitro cytotoxic activity of complexes 1 and 2 was evaluated by the MTT[3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl- 2H-tetrazolium bromide] method. Complex I shows higher anticancer potency than complex 2 against four tumor cell lines. Further mechanism study indicates that complexes 1 and 2 can cause cell cycle arrest in the G2/M phase.     

CF_2自由基_态伸缩振动频率的测定

CF2自由基作为许多碳氟化合反应的中间物及它在大气化学中的影响而一直引起人们的研究兴趣同．自从1950年Venkateswarlu首次观测到它的光谱以来同，对CF2电子基态的理论及实验研究方面都有相当多的数据积累．特别是近年来高分辨红外光谱对CF2电子基态提供了结论性的数据[3,4]．     

An Improved Approach towards Multi-Agent Pursuit–Evasion Game Decision-Making Using Deep Reinforcement Learning

A pursuit–evasion game is a classical maneuver confrontation problem in the multi-agent systems (MASs) domain. An online decision technique based on deep reinforcement learning (DRL) was developed in this paper to address the problem of environment sensing and decision-making in pursuit–evasion games. A control-oriented framework developed from the DRL-based multi-agent deep deterministic policy gradient (MADDPG) algorithm was built to implement multi-agent cooperative decision-making to overcome the limitation of the tedious state variables required for the traditionally complicated modeling process. To address the effects of errors between a model and a real scenario, this paper introduces adversarial disturbances. It also proposes a novel adversarial attack trick and adversarial learning MADDPG (A2-MADDPG) algorithm. By introducing an adversarial attack trick for the agents themselves, uncertainties of the real world are modeled, thereby optimizing robust training. During the training process, adversarial learning was incorporated into our algorithm to preprocess the actions of multiple agents, which enabled them to properly respond to uncertain dynamic changes in MASs. Experimental results verified that the proposed approach provides superior performance and effectiveness for pursuers and evaders, and both can learn the corresponding confrontational strategy during training.