紫色光合细菌ThermochromatiumTepidum捕光天线复合物2的激发态动力学

Thermochromatium (Tch.) tepidum是一种中等嗜热的紫色光合细菌, 最佳生长温度为48-50 ℃; 其捕光天线复合物2 (LH2)含有非均一性脱辅基蛋白和类胡萝卜素(Car), 且高分辨率晶体结构未知. 我们通过超快光谱研究了分别采用去垢剂n-dodecyl-β-D-maltoside (DDM)和lauryldimethylamine oxide (LDAO)制备的LH2的激发态动力学, 观测到由细菌叶绿素(BChl)的Qy态介导的B800-to-B850单重态能量传递过程(时间尺度~1.2 ps, 用DDM制备的LH2), 以及由类胡萝卜素S2态介导的Car-to-Car和Car-to-BChl 单重态能量传递过程(~100 fs). 结果表明C=C共轭双键数目(NC=C)为11和12的两类Car共处于同一LH2复合物中; 相对于源自其它菌种、构成组分相对简单的LH2, Tch. tepidum的LH2中B800-B850的相对取向有较大差异. 本工作发现LH2中低含量类胡萝卜素组分anhydrorhodovibrin (NC=C=12)起着高效“能量陷阱”的作用, 可能是一种重要的光保护机制; 基于类胡萝卜素的超快谱带位移现象提出(OH-)spirilloxanthin(NC=C=13)距BChl分子可能比其它类胡萝卜素更近. 这些研究结果有助于进一步理解苛刻自然条件下生长的Tch. tepidum的捕光和光保护机制.     

紫菌外周捕光天线LH2中的超快能量弛豫

主要用飞秒抽运-探测技术观察了紫细菌Rb. sphaeroides 601外周捕光天线LH2中细菌叶绿素(BChl)之间的能量传递过程. 在783 nm的激光激发B800情况下, 在B800到B850的能量传递之前, 存在一个约0.35 ps的分子内能量重新分布过程; 通过调节激发波长, 清楚地观察到激发态BChl分子的动力学演变过程. 结果表明基态漂白和激发态吸收存在明显的竞争, 同时在818 nm处出现一个鞍点, 说明在B800的激发态和B850的上激子态存在快速、高效的能量传递; B850分子上激子态的激发能将通过内转换向次最低激发态快速弛豫, 并导致最低激发态布局和分子构象变化.     

HL-LH2中色素分子间的单重激发态能量传递

采用飞秒时间分辨吸收光谱手段观测了在500和800 nm激发下高光培养的紫色光合细菌Rhodopseu-domonas(Rps). palustris外周捕光天线LH2(HL-LH2)中不同共轭链长类胡萝卜素(Carotenoid, 简称Car)和细菌叶绿素a(Bacteriachlorophyll a, 简称BChl a)的特征吸收光谱. 光谱动力学分析结果表明, HL-LH2中不同Car分子间可能存在复杂的单重激发态能量平衡过程, Car分子同时向BChl a分子发生多途径的单重激发态能量传递, B800主要接受来自Car的S2和S1态能量; B850则主要接受来自长共轭链Car(共轭双键数目n=13)的S1态和B800的激发态能量, 整个能量传递过程在3~5 ps内完成.     

丁酸甲酯单分子解离的非谐振效应

使用MP2/6-311++G（2d,2p）方法和基组,计算了丁酸甲酯单分子解离反应体系详细的势能面。应用RRKM理论,计算了在1000-5000 K的温度范围内的正则系综的速率常数。与此同时,在微正则系综下,我们计算了温度为1000-5000 K对应的能量从451.92到1519.52 kJ·mol^-1的速率常数。计算结果表明反应通道2、4和5的非谐振效应比较明显。因此对于丁酸甲酯单分子解离反应体系来说其非谐振效应是不能忽视的。     

胶体泡沫(CGA)排液动力学研究

分别对三种表面活性剂, 十二烷基硫酸钠(SDS)、十六烷基三甲基溴化铵(HTAB)以及吐温80 (Tween 80)形成的胶体泡沫(CGA)的排液过程动力学进行了研究. 讨论了表面活性剂种类和浓度, 体系温度等对CGA排液过程的影响. 运用非线性最小二乘法拟合, 推出了表征CGA排液过程的动力学模型: V_t＝V_maxtⁿ/(Kⁿ＋tⁿ), 式中, V_t表示时间t时的排液量(mL), t表示排液时间(s), V_max表示CGA最大排液量(mL)的模型参数, K为模型参数, 表征CGA排液过程的半衰期t_1/2, n为排液曲线反曲特征指数. 通过该模型计算出了表征CGA排液过程的速率常数k_d和半衰期t_1/2等参数. 并通过lnk_d～T^－1的线性关系, 证明了该模型符合Arrhenius方程. 最后, 通过对CGA排液速率随时间的变化分析, 解析了CGA排液过程的“两段论”机理.     

HS+HO2气相反应机理及主通道速率常数的理论研究

采用CCSD(T)/6-311++G(3df, 2pd)//B3LYP/6-311+G(2df, 2p)双水平计算方法构建了HO₂+HS反应体系的单、三重态反应势能面,并对该反应主通道的速率常数进行了研究。研究结果表明,标题反应经历了八条反应通道,其中三重态反应通道R1是标题反应主通道。此通道包含路径Path 1 (R → ³IM1 → ³TS1 → P1(³O₂+H₂S))和Path 1a (R → ³IM1a → ³TS1a → P1(³O₂+H₂S))两条路径。利用经典过渡态理论(TST)与变分过渡态理论(CVT)并结合小曲率隧道效应模型(SCT),分别计算了主路径Path 1和Path 1a在200-800 K温度范围内的速率常数k^TST、k^CVT和k^CVT/SCT,在此温度区间内路径Path 1和Path 1a具有负温度系数效应。速率常数计算结果显示,对主路径Path 1和Path 1a而言,变分效应在计算温度段内有一定影响,与此同时量子力学隧道效应在低温段有显著影响。路径Path 1和Path 1a的CVT/SCT速率常数的三参数表达式分别为k₁^CVT/SCT(200-800 K) = 1.54×10^-5T^-2.70exp(1154/T) cm³ ·molecule^-1·s^-1和k_1a^CVT/SCT(200-800 K) = 5.82×10^-8T^-1.84exp(1388/T) cm³·molecule^-1·s^-1。     

H2FCS单分子分解反应的直接动力学研究

采用量子化学QCISD(T)/6-311++G(d,p)//B3LYP/6-311+G(d,p)方法研究了H2FCS单分子分解反应的微观动力学性质, 构建了反应势能剖面. 利用经典过渡态理论(TST)与变分过渡态理论(CVT)并结合小曲率隧道效应模型(SCT), 分别计算了在200～3000 K温度范围内的速率常数kTST、kCVT和kCVT/SCT. 计算结果表明, H2FCS可经过不同的反应通道生成10种小分子产物, 脱H反应和HF消去反应为标题反应的主反应通道, 其中HF消去反应产物HCS可由两条反应通道生成. 在200~3000 K温度区间内得到三条反应通道的表观反应速率常数三参数表达式分别为 , 和 . 速率常数计算结果显示, 量子力学隧道效应在低温区间对反应速率常数的影响显著, 而变分效应在计算温度范围内可以忽略.     

二元阴、 阳离子表面活性剂调控合成不同形貌的介孔二氧化硅

经过简单的水热处理, 以二元阴、 阳离子表面活性剂[十六烷基三甲基溴化铵(CTAB)和十二烷基磺酸钠(SDS)分别作为阳离子表面活性剂和阴离子表面活性剂]为模板剂合成了不同形貌的介孔二氧化硅. 通过调控2种表面活性剂摩尔分数R(R=n(SDS)/[n(SDS)+n(CTAB)]), 合成了多种形貌的介孔二氧化硅. 对合成的不同形貌样品通过扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 X射线粉末衍射仪(XRD) 及比表面和孔隙分析仪进行了表征. 结果表明, 随着R值从0.01变化到0.50, 介孔二氧化硅的形貌经历了一系列规律性的变化, 出现了二维六方、 层状相和反相堆积的形貌: 在R=0.01~0.18之间, 主要产物为六方相棒状结构, 且长径比随着R值增大而增大; 在R=0.20~0.28之间主要得到空心泡状结构且具有明显的演变过程; 在R=0.32~0.40之间发生了多层囊泡到单层囊泡的结构转变; 当R值超过一定范围时会产生反相堆积的形貌. 分析认为, SDS在加入过程中通过影响堆积参数g影响胶束的形貌变化, 调控了不同形貌介孔二氧化硅的合成. 各阶段产物形貌和R值的变化有直接关系, 可通过改变R值来合成特定形貌的产物.     

F+CH2CO的反应机理和动力学研究

用G3(MP2)方法对F与CH₂CO的反应进行研究,揭示了该反应的加成-消除机理.F原子首先与CH₂CO作用形成富能的中间体CH₂FCO^*,此加成反应为无势垒过程.富能的CH₂FCO^*可进一步发生解离或异构化反应生成各种可能的产物.其中CO和CH₂F可能为反应的主要产物.根据从头算的结果,用RRKM-TST理论计算该反应的速率常数.总包反应速率常数与温度存在弱的依赖关系,与总压力无关.     

微量热法测定细菌的临界生长温度

应用微量热学的方法,我们已能成功地测得细菌生长过程的热谱,这种热谱包含着有关细菌生长代谢过程的丰富信息,例如对热谱曲线的指数生长段进行解析,可得出细菌生长的速率常数、激活能和有关的热力学参数。故采用微量热法测定细菌在不同培养温度下的生长速率常数,利用计算机拟合出相应k(速率常数)和T(培养温度)的线性关系式后,若把生长速率为零的温度定义为临界生长温度时,就可以根据由上述实验所得的k～T线性关系式求得细菌的临界生长温度。本工作仍采用微量热法对福氏志贺氏菌(S. flexneri)和大肠埃希氏菌(E. coli)进行实验测定。按文献的方法求出它们在不同温度下的生长速率常数;对于大肠埃希氏菌还用几种不同的培养基分别进行实验测定。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Summary of development of the theory of stability of colloids and thin films

In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Thermodynamics of the formation of oxosulfides of rare-earth elements

The enthalpies of solution of several oxosulfides of rare-earth elements and the high-temperature enthalpies of oxosulfides and oxosulfates of lanthanum and yttrium were measured using solution calorimetry and high-temperature microcalorimetry techniques. Standard enthalpies of formation and some thermodynamic properties of oxosulfides and oxosulfates were calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2 pp. 294–297, February, 1997.     

恶臭嗅辨实验室建设探讨

针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。