InnNa和InnNa^＋（n=2—8）的团簇结构和电子性质

在密度泛函理论B3LYP水平上,对Innna和InnNa+(n=2-8)团簇进行了结构优化和振动频率计算.计算结果表明,InnNa(n=2、3、4、6)最稳定结构中的对称性分别为C2v、C3v、C4v和C2v而InnNa(n=5、7、8)的最稳定结构的对称性为C1点群.从InnNa(n=4-8)的最稳定结构可以看出,Na原子均位于四个In原子形成的四边形而上.对于InnNa+(n=2-8),除了In2Na+和In7Na+,其它结构都与其中性结构相似.进一步计算InnNa(n=2-8)团簇的平均结合能、能量的二阶差分以及绝热电离能表明,InnNa(n=2-8)团簇能量的二阶差分呈现奇偶交替特征,In4Na和In6Na较其它团簇更为稳定,而且理论计算得到的绝热电离能和实验结果吻合得很好.     

Lien元素簇合物的成键作用

镇元素簇合物是人们最感兴趣的簇合物之一l‘－’］．已有的。作主要是研究它的稳定性和电子结构，对其成键性质还研究得不多·为止匕我们对Lkin为元素簇合物中所含原子个数，e为该化合物的电荷）进行了定域化研究，并得出一些有意义的结果·1计算我4rl采用GAMESS90程序m，在4－31G基组下进行了正则分子轨道SCFi十算（闭壳层采用RHF，开壳层采用UHF）．然后，以QSU90程序问，用B0yS方法进行了定域化计算，得到定域分子轨道（LM），再根据LMO的系数和集居数分析，判断各分子中原子的成键情况问．共计算了18个簇合物．它们的原子数…     

金红石型TiO2表面嵌入簇模型的密度泛函研究

应用金属氧化物簇模型的选取原则和密度泛函方法,对一系列嵌入族模型金红石型(TiO₂)n(n=2～15)的表面体系进行了研究,计算结果表明,合理选取的嵌入簇模型可以得到与实验一致的固体表面电子结构,通过描述表面的性质能够给出表面金属吸附的电子行为的定性解释,进一步证实了该模型的密度泛函研究能够用于固体金属氧化物的簇-表面类比.揭示了选择合理的簇模型是保证族表面类比方法成功的主要因素.     

AlnO2团簇结构和稳定性的量子化学研究

采用密度泛函理论（DFT）的B3LYP方法,在6-311G＊＊水平上对AlnO2（n=1～10）团簇的几何和电子结构进行了理论计算.讨论了混合团簇的基态结构与振动频率,以及电荷转移与成键特征.结果表明,富氧的AlO2基态结构是以Al原子为核心的线状结构,双聚体和富铝的AlnO2基态结构是以2个O原子为中心的AlmO（m...     

金属氧化物SPC簇模型方法——嵌入簇点电量的确定

探讨和比较了确定金属氧化物晶体点电荷量的几种自洽条件的优劣 ,并使用abinitioHF方法对在不同点电荷量嵌入环境下MgO簇电子性质进行了研究 .计算结果表明 :点电荷量的大小会明显影响嵌入簇的电子性质 ;即使MgO被通常认为是纯的离子型氧化物 ,点电荷量取为表观化合价± 2 ,仍过高地估计了Madelung势 ,嵌入簇与点电荷之间应满足一定的自洽条件 ;使用点电荷为嵌入环境时 ,即使达到电荷自洽、偶极矩自洽或势自洽 ,簇模型计算结果仍与固体性质存在一定的偏差 ;将点电荷进行球谐展开 ,赋予其连续变化的电荷密度分布后 ,得到了一个对固体整体性质描述较好的SPC簇模型 .     

AlmN(m=2～9)团簇结构与稳定性的DFT研究

用密度泛涵理论 (DFT)的 B3LYP方法在 6-31G水平上对 AlmN(m=2～ 9)团簇的几何构型、电子结构、振动频率等性质进行了理论研究.给出了以 Alm团簇作为设计 AlmN类结构的母体,考虑在不同位置上结合 N原子的结构,可以较快找到 AlmN类团簇基态结构的一种方法.通过对基态结构的几何参数分析发现, m< 4的结构只存在 Al- N键; m≥ 4的结构 , Al- N键和 Al- Al键共存.对基态结构的绝热电离能讨论结果表明,只存在 Al- N键的 Al2N和 Al3N团簇较稳定.     

AlmN+(m = 3～9)团簇的结构与稳定性

用密度泛涵理论(DFT)的B3LYP方法在6-31G水平上对AlmN+(m=3~9)团簇的几何构型、电子结构、振动频率等性质进行了理论研究,通过对基态结构的几何参数分析发现,m≥4的结构中AlN键和AlAl键共存。对团簇能量讨论的结果表明,m为偶数的AlmN+团簇比m为奇数的稳定。     

碱金属团簇结构和稳定性的Hueckel—Hubbard方法研究

用Ｈｕｅｃｋｅｌ－Ｈｕｂｂａｒｄ理论及作者所建议的参数化方法，对碱金属团簇Ａｎ，Ａ＾＋ｎ，Ａ＾－ｎ的结构和碎化进行计算和分析，结果表明：ｎ≤５时团簇呈平面结构，几率大的碎化对应着中性单原子或中性二聚物的生成，团簇的稳定性随ｎ的变化呈出奇偶性，中性簇与离子簇的奇偶性上反，这些定性结果与实验及其它更精确算法的结果基本一致。     

AlnO±2团簇结构的几何特征与稳定性

采用密度泛函理论(DFT)的B3LYP方法,在6-311G**水平上对AInO±2 (n=1-10)团簇的几何和电子结构进行了理论计算.讨论了混合团簇的基态结构与振动频率,以及电荷转移与分子轨道.结果表明,AlnO±2(n＞1)团簇的基态结构都是2个较小的AlmO(m＜n)分子碎片通过Al原子或1个Al4O2局部结构与Al簇相结合形成的.通过对基态结构的能量分析,得到了AlnO±2团簇的稳定性信息.     

杂质对硬球系统团簇成核临界条件的影响

通过CS状态方程及熵极大原理在多元胶体系统研究了杂质对硬球系统团簇成核临界条件的影响. 极少量元素或杂质的小胶球对系统成核的临界条件的影响也是不可忽略的： 成核的临界体积分量显著地降低;此外,研究还发现杂质对成核的临界尺寸影响较少.     

氧化铁系催化剂晶格氧和电子传递作用初探

在考察乙苯脱氢工业氧化铁系催化剂的中变(逆)活性和脱氧机理实验基础上,结合有关报道,探讨了氧化铁系催化剂晶格氧及电子传递作用。     

PHOTOSENSITIVE BILAYER MEMBRANES AS MODEL SYSTEMS FOR PHOTOBIOLOGICAL PROCESSES

Abstract— Photobiological processes such as photosynthesis, photomorphogenesis, photomovement, and photoreception are all associated with the membranous portions of cells. The unique properties of membrane surfaces are apparently required to achieve biologically relevant energy transduction and photocontrol phenomena and consequently the use of model membrane systems is suggested as an advantageous approach to elucidation of the important physical and chemical processes involved. Black lipid membrane (BLM) and liposome techniques are critically reviewed as preferred techniques for constructing and manipulating lipid bilayers. The lipid bilayer is considered to be the basic foundation for biological membrane models, and specific physical phenomena observed with the bilayers and their biological ramifications are analyzed. Light-stimulated polarization of the membrane and electron transfer across the bilayer are viewed as appropriate analogs of vision and photosynthesis, respectively. Bilayer-adsorbed dye experiments are the simplest systems explored that exhibit polarization and charge transfer across the membrane. Chloroplast extract BLM experiments are cited as an example of the light-stimulated transfer of electrons across the membrane under the influence of a preexisting redox gradient. Biliprotein (phycocyanin or phycoerythrin) on one side of the chloroplast extract membrane permits the direction of electron flow across the membrane so that a redox gradient is created in a manner truly analogous to photosynthesis. The potential for solar energy conversion from such membranes is explicitly considered utilizing a schematic photoelectrochemical cell. Model membranes containing bacterial rhodopsin and phytochrome represent examples of ionic gradients that result in biological energy transduction. Studies of membranes that exhibit transient photoeffects are considered potentially relevant for the elucidation of phototaxis. The analysis of many properties of photosensitive membranes is greatly aided by the use of appropriate theoretical models. It is apparent that there is a great potential for the application of photosensitive model membranes in many research areas involving complex photobiological phenomena and novel methods for solar energy conversion.     

蛋白质分子的HNP格点模型

从 6 0种球形蛋白质的结构出发 ,采用Miyazawa Jernigan相互作用矩阵 ,计算了蛋白质分子中氨基酸之间的相互作用能 .发现构成蛋白质分子的 2 0种氨基酸可分成疏水 (Hydrophobic ,H)、中性 (Neutral,N)、亲水(Hydrophilic ,P)基团 .在计算它们之间相互作用能的基础上 ,建立了蛋白质分子的HNP格点模型 .用这个模型计算了二维蛋白质分子在自然态 (Nativestate)时的构象性质 .同时研究了氨基酸序列为HHNHNPNHPP HPNPPHPHPPHHPHNH的折叠过程 ,得到其基态能量为 - 6 4 89RT .这能为研究球形蛋白质的构象性质及折叠过程提供一种更合理的格点模型     

MECHANICAL MODEL FOR TWO-PHASE POLYMER BLEND SYSTEMS WITH THE CHARACTERISTICS OF PHASE INVERSION

For two-phase polymer blend systems, the phase inversion will take place as the blendcomposition is changed. In this paper a mechanical model has been proposed to describe themodulus-composition relation in the phase inversion region. The application of the mechanicalmodel to two polyurethane blend systems has been studied. It was found that the theoreticalprediction for the modulus-composition relation is quite consistent with the experimentalresults. Furthermore, the characteristics of the phase inversion can be determined uniquelyby the parameters involved in the mechanical model.     

用于流化床燃烧脱硫的石灰石固硫反应模型

在模拟流化床燃烧脱硫气氛和温度条件下，建立了石灰石煅与固硫反应同时进行的数学模型。描述了两反应过程之间的相互影响及石灰石内部晶粒大小、孔隙率和运行参数对反应过程的影响。模型的合理性通过理论计算和实验结果的比较得到验证。     

ACTION SPECTRA FOR THE PHOTOLYSIS OF 5-IODODEOXYURIDINE IN DNA AND RELATED MODEL SYSTEMS: EVIDENCE FOR SHORT-RANGE ENERGY TRANSFER*

Abstract— A variety of polynucleotides containing 5-iodouracil residues were irradiated in aqueous solution with wavelengths between 240 and 313 nm. From the rate of deiodination the photochemical cross sections (a_B) were determined as a function of the irradiation wavelength (A). The expression was used to relate the observed values of _B to the intrinsic quantum yield, φ_INT, and to the absorption cross sections, and for the iodinated and noniodinated residues, respectively. φ_INT is the probability an excited iodouracil residue will deiodinate, while the parameter b is a measure of the number of noniodinated bases which contribute their excitation energy to the deiodination process. For IdUrd and poly(5-iodouridylic acid), the average values of φ_INT calculated from the experimental _B values were 0.0202 and 0.0188, respectively, for irradiation in air. In native, denatured, and depurinated DNA in which IdUrd was substituted for 10% of the Thd, the average φ_INT values were 0.0069, 0.0088, and 0.0153, respectively, indicating an enhancement in φ_INT upon decreasing the order of the polynucleotide. In contrast, the average values of b bor the same set of compounds were found to be 4 , 2 and 0.4, respectively, indicating a decrease in b with decreasing polynucleotide order, i.e. a loss of base stacking decreases the extent of energy transfer. A value of b= 4 for native DNA is assumed to mean that the extent of energy transfer in native DNA is limited to four base donors per iodouracil residue serving as an energy trap.     

APPLICATIONS OF ISOCYANATION FOR POLYMER SYSTEMS

Isocyanate is a highly unsaturated compound. It reacts readily with compounds containing active proton such as alcohol, phenol, acid, and amine through isocyanation. In this article, this very useful synthesis route is reviewed with regard to applications of isocyanation for the synthesis of polyurethanes, polyurethane ionomers, polyamides, polyimides, polyamide-imides, interpenetrating network polymers, polymers for membrane separation, comb- and star-polymers, functional monomers, and new stabilizers.

     

MODEL FOR THE RATIONALIZATION OF MAGNETIC FIELD EFFECTS IN VIVO. APPLICATION OF THE RADICAL-PAIR MECHANISM TO BIOLOGICAL SYSTEMS

Abstract: A model for magnetic field effects in biological systems is proposed. This model employs the basic concepts of the radical pair mechanism, and predicts that magnetic fields will increase the average radical concentration, lengthen their lifetime and enhance the probability of radical reactions with cellular components. The relevance of these effects in relation to cancer initiation, promotion and progression is discussed.     

气相色谱法测量聚苯乙烯——挥发组分二元系统中挥发组分在无限稀时的活度系数

溶液中各组分的活度系数及其随温度的变化,是与溶液性质有关的基本物理化学数据,它反映出溶液中溶剂分子和溶质分子之间的相互作用,是研究溶液性质所不可少的。对于高聚物溶液性质的了解,溶液中各组分活度系数的测定也是必要的工作,但迄今在这方面的工作不多,我们认为有必要弥补这一缺陷。     

单一高分子白光材料

首先阐明了单一白光高分子材料体系的构造原理——"部分能量转移和电荷限制机制",然后分别从双色白光高分子和三色白光高分子两个方面,详细介绍了单一白光高分子材料体系的发展历程与研究进展,并在此基础上,展望了单一高分子白光材料未来的发展方向.