Rate Coefficients and Kinetic Isotope Effects of Cl+XCl→XCl+Cl (X=H,D, Mu) Reactions from Ring Polymer Molecular Dynamics

The ring-polymer molecular dynamics (RPMD) was used to calculate the thermal rate coefficients and kinetic isotope effects of the heavy-light-heavy abstract reaction Cl+XCl\begin{document}$ \rightarrow $\end{document}XCl+Cl (X = H, D, Mu). For the Cl+HCl reaction, the excellent agreement between the RPMD and experimental values provides a strong proof for the accuracy of the RPMD theory. And the RPMD results are also consistent with results from other theoretical methods including improved-canonical-variational-theory and quantum dynamics. The most novel finding is that there is a double peak in Cl+MuCl reaction near the transition state, leaving a free energy well. It comes from the mode softening of the reaction system at the peak of the potential energy surface. Such an explicit free energy well suggests strongly there is an observable resonance. And for the Cl+DCl reaction, the RPMD rate coefficient again gives very accurate results compared with experimental values. The only exception is at the temperature of 312.5 K, results from RPMD and all other theoretical methods are close to each other but slightly lower than the experimental value, which indicates experimental or potential energy surface deficiency.     

高分子填料在生物法处理废水中的应用进展

对生物法处理废水用的高分子填料进行了综述。首先,从无机高分子填料、有机高分子填料两方面介绍了其应用特点及对废水中有机物的作用机理和去除效果;其次,介绍了新型生物填料,主要从生物亲和亲水磁性填料和酶促生物填料两方面介绍其在废水处理中的应用。     

含全氟烃基的联苯酯类液晶的合成及其介晶性

全氟烃或半氟烃链无手性液晶化合物可能呈现铁电液晶性, 具有较大的学术及应用价值而受到研究人员的重视. 合成了全氟己基苯甲酸联苯酯类液晶化合物: ROC₆H₄C₆H₄O₂CC₆H₄C₆F₁₃ (3a～3e), C₃H₇C₆H₄C₆H₄O₂CC₆H₄C₆F₁₃ (6a)及其烃衍生物. 用差示扫描量热法(DSC)和偏光显微镜(POM)对其介晶性研究发现: 烃衍生物呈有序度较低的向列相, 熔点较高, 清亮点较低, 液晶相较窄. 全氟烃基取代的化合物出现多个有序度较高的近晶相, 熔点较低, 清亮点高, 介晶相温度范围宽.     

含亚胺和胆甾烯基不对称液晶二聚体的合成及介晶性

报道含亚胺和胆甾烯基不对称液晶二聚体化合物XC₆H₄N＝CHC₆H₄OC₁₀H₂₀COOCh* [X＝OC_nH_2n＋1, (n＝1～12,14), F, Cl, Br, CH₃] (1a～1q)的合成及液晶性. 目标化合物通过600 MHz ¹H NMR和元素分析进行了结构表征. 其介晶性通过偏光显微镜(POM)和差示扫描量热计(DSC)进行了研究. 结果显示: 所有化合物都具有胆甾相(N*). 对于烷氧基系列(X＝OC_nH_2n＋1), 有部分化合物还呈现了近晶A相(S_A), 且随着末端烷氧链长度的增加, 化合物的清亮点呈现缓慢下降的趋势, 而化合物从胆甾相到各向同性液体转变的熵变(ΔS_N*→I)则呈现奇-偶效应. 同时我们对比研究了取代基X对胆甾相稳定性的影响, 发现取代基X对胆甾相的稳定性高低顺序为: MeO＞Cl＞Br＞Me＞F. 这些结果证实了末端取代基的改变对化合物的相转变温度以及介晶性质有显著的影响.     

硼氢化反应机理Ⅳ——甲基腈硼氢化反应的反应途径解析(英文)

利用量子化学从头计算法ＲＨＦ／４－３１Ｇ基组对ＣＨ３ＣＮ＋ＢＨ３反应进行了理论研究．ＩＲＣ分析表明：甲基腈与甲硼烷通过“类四中心”过渡态,直接加成生成产物．计算的活化能是３４６２６８ｋＪ／ｍｏｌ．计算发现在反应途径中,ＢＨ３分子片随着与ＣＨ３ＣＮ分子片的接近经历一个由电子受体到电子授体的变化,并用前线轨道理论作了解释．     

微波化学温度模拟研究进展

在微波化学研究中,通过数学模拟分析微波作用在化学体系的温度分布及变化,有助于控制微波加热过程,了解微波与物质之间的相互作用机理.本文针对微波化学数值模拟的特点,系统介绍了各种方法及模拟过程,对数值模拟分析中的关键问题进行了讨论,综述了近年来数值模拟温度分布在微波化学中的应用,提出了目前的研究难点,并展望了发展趋势.     

Analysis of viscosity abnormalities of polyelectrolytes in dilute solutions

It was found that the interface effects in viscous capillary flow influenced the process of viscosity measurement greatly,and the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute solution region were ascribed to interface effect.According to this theory,we have reviewed the previous viscosity data of derivatives of poly-2- vinylpyridine reported by Maclay and Fuoss first.Then,the abnormal viscosity behaviors of a series of sodium polystyrene sulfonate samples with various molecular weights in dilute aqueous solutions were studied further.The solute adsorption behaviors and structural information of polymers have been discussed carefully.     

毛冬青总皂苷对大鼠脑缺血再灌注损伤的保护作用及血液微量元素影响

目的研究毛冬青总皂苷对脑缺血再灌注损伤的保护作用,并初步探讨其血液微量元素的影响。方法动物随机分为假手术组、模型组、毛冬青总皂苷(高、中、低)剂量组及阳性药物对照组,运用大鼠大脑中动脉栓塞,制作脑缺血再灌注损伤模型,缺血10 min后,给药组及阳性药物组于舌下静脉给予高、中、低剂量的毛冬青总皂苷及假手术组、模型组给予等体积的溶剂。缺血60 min再灌注24 h后,每组取8只大鼠断头取脑,TTC染色,测定脑梗死体积;取血,测定血液中3种微量元素Ca、Zn、Cu的含量。结果毛冬青总皂苷组与模型组相比,毛冬青总皂苷治疗组脑梗死体积减小,病理变化较轻;模型组与假手术组比较血液中Ca、Cu含量增加明显有统计学意义,Zn含量明显降低与假手术组比较有统计学意义(P0.05),毛冬青高、中、低剂量组与模型组比较Ca、Cu含量明显降低,Zn含量明显升高,而且呈明显的量效关系,与模型组比较有统计学意义(P0.05)。结论毛冬青总皂苷对脑缺血再灌注损伤具有一定的保护作用,其保护机制与毛冬青总皂苷抗氧化作用及增强氧自由基的清除有关。     

Studies on the Structure and Properties of Cordierite Synthesized by Talc-Magnesite

Homogeneous cordierite has been synthesized at low cost by talc-magnesite and coal gangue as the main raw materials. The mechanism of synthesizing cordierite under such a com- posing system of raw materials, and the effect of temperature on the crystal cell parameters and microstructure and thermal expansion coefficient of cordierite crystal have been studied via testing methods of XRD, SEM, etc. The result shows that the homogeneous cordierite can be synthesized by the systematic composing materials of “talc-magnesite—coal gangue—talc” with heat pre- servation at 1350 ℃ for 1 h; as the keeping time is prolonged, Al3+ and Mg2+ in cordierite crystal are replaced by a few impurity ions such as Fe3+, Fe2+, etc., and the crystal cell parameters of cordierite present an increase trend; as the high-temperature heat preservation is prolonged, the content of glassy phase in the sample is increased, its density is improved, and its thermal expansion coeffi- cient presents an increase trend.