金属超微粒子-介质复合薄膜(Ag-BaO)的光吸收特性

测量了真空热蒸发沉积法制备的贵金属Ａｇ超微粒子－介质（ＢａＯ）复合薄膜近紫外到可见的吸收光谱。这种薄膜的透射电镜显微像表明，Ａｇ在介质中形成了较均匀的超微粒子，粒径为１５ｎｍ。观察到吸收谱在４１０ｎｍ处有明显的等离子激元共振吸收峰，这是电偶极振荡的吸收。与以往文献的结果做了比较，讨论了吸收光谱对金属微粒尺寸的依赖关系。     

流化床内超细颗粒的流动

基于气体分子运动论和颗粒动理学,建立超细颗粒气固两相湍流流动模型,模型考虑了气相与颗粒聚团之间以及颗粒聚团之间的动量和能量的传递和耗散。建立超细颗粒固相粘性系数、超细颗粒压力等物性参数计算模型。超细颗粒的聚团改变了单颗粒碰撞动力学以及颗粒相压力、粘性系数等输运特性。模型模拟计算颗粒聚团直径分布与Zhaolin等[1]实测值相吻合。     

A discrete velocity model of a gas: Global in time solutions of the BBGKY hierarchy

In the present paper we study the evolution of a system of hard disks moving in the plane with a finite number of velocities as in the framework of a discrete velocity model of the Enskog equation, proposed in previous papers. Starting from the BBGKY hierarchy of such a system we give existence and uniqueness results for the initial value problem in suitable Banach spaces. In particular, the main result presented is the global in time weak solution to the BBGKY hierarchy for local equilibrium initial data, in the thermodynamic limit.     

Theoretical investigation of the coexistence of α and β-nitric acid trihydrates (NAT) molecular conformations

In this letter we document the possibility of the existence of a second molecular configuration for nitric acid trihydrates. Density functional theory (DFT) methods have been used for studying the nitric acid trihydrates α and β-NAT conformations, their spectroscopic and thermodynamics properties and dipole moments have been calculated. This study describes the gas–solid phase transition of the NAT and provides two possible pathways for the molecular structure transformation between α and β-NAT.     

Preparation and magnetic properties of ultrafine particles of FeNi alloys

Ultrafine particles (UFP) of six kinds of FeNi alloys were synthesized by the method of hydrogen plasma reaction. The prepared UFP samples were examined by X-ray diffraction, electron transmission microscopy and magnetic measurement. The spherical FeNi UFP alloys with a mean particle size less than 35 nm can be prepared with a production rate much higher than by conventional methods. The phase constitution of UFP alloys is different from the equilibrium phase diagram owing to rapid condensation of evaporated metal gases. Although the magnetization for the UFP alloys has almost the same temperature dependence as that of the bulk alloys, the saturation magnetization remarkably decreases as the bulk alloys change into the UFP alloys.     

Dispersion polymerization in polar solvents

The effect of the nitrogen purge, monomer purification, type of agitation, and presence of costabilizer on the particle size distribution (PSD) was investigated in the dispersion po-lymerization of styrene in ethanol and in the dispersion copolymerization of styrene and butyl acrylate in a water–ethanol mixture. Purging with nitrogen and, to a lesser extent, monomer purification, were of paramount importance to achieve monodispersity. The type of agitation had a week effect on the PSD, whereas the presence of costabilizer had no effect on the PSD. © 1995 John Wiley & Sons, Inc.     

Open systems of splitting particles

Systems with an infinite variety of types of splitting particles are investigated. It is shown that if there is a stationary source of particles but no sink, a steady state with finite density of each species is nevertheless possible due to the infinite number of degrees of freedom. It is demonstrated that the limiting (steady) state is independent of the initial state of the system. Typical features of the steady state, which do not depend on the particle splitting law, are shown.     

XANES studies of unoccupied electronic states and local real structure of some antimony chalcogenides

Summary The X-rayL absorption edges of antimony and iodine in SbSI, Sb₂S₃, Sb₂S₅ have been measured with high resolution using synchrotron radiation. It is shown that the density of the unoccupied levels in the conduction band is adequate to interpret the edge structures between 0 and 10 eV. These structures and the chemical shifts of the three compounds are compared: a striking similarity of the electric charge of antimony and of the electronic structure in the bottom of the conduction band is found. The structures between 10 and 50 eV are analysed and interpreted in terms of stereochemical co-ordination. The nonexistence of Sb₂S₅ as a stoichiometric compound is confirmed.

---

Riassunto Le soglie di assorbimentoL dell'antimonio e dello iodio sono state misurate ad alta risoluzione con luce di sincrotrone in SbSI, Sb₂S₃ e Sb₂S₅. La densità degli stati liberi nella banda di conduzione è risultata adeguata per interpretare le strutture di soglia tra 0 e 10 eV. Il confronto delle strutture di soglia e degli spostamenti chimici dei tre composti ha rivelato una notevole somiglianza nella carica dell'atomo di antimonio e nella struttura della parte bassa della banda di conduzione. Le strutture tra 10 e 50 eV sopra la soglia sono state analizzate ed interpretate in relazione alla coordinazione stereochimica. è stata confermata la non esistenza del Sb₂S₅ come composto stechiometrico.

---

Резюме Были определны рентгеновскиеL края поглощения суьмы и йода в SbSI, Sb₂S₃, Sb₂S₅ с высоким разрешением, используя синхротронное излучение. Показывается, что плотность незаполненных уровней в зоне проводимости адекватно описывает структуры в области от 0 до 10 эВ. Для трех соединений проводится сравнение полученных структур и химических сдвигов. Обнаружено удивительное подобие электрического заряда сурьмы и электронной структуры на дне зоны проводимости. Анализируются структуры в области от 50 эВ и предлагается их интерпрпретация. Отмечается отсутствие Sb₂S₅, как стехиометрического соединения.

     

Stimuli‐responsive ABC triblock copolymers by sequential living cationic copolymerization: Multistage self‐assemblies through micellization to open association

Stimuli‐responsive ABC triblock copolymers with three segments with different phase‐separation temperatures were synthesized via sequential living cationic copolymerization. The triblock copolymers exhibited sensitive thermally induced physical gelation (open association) through the formation of micelles. For example, an aqueous solution of EOVE₂₀₀‐b‐MOVE₂₀₀‐b‐EOEOVE₂₀₀ [where EOVE is 2‐ethoxyethyl vinyl ether, MOVE is 2‐methoxethyl vinyl ether and EOEOVE is 2‐(2‐ethoxy)ethoxyethyl vinyl ether; the order of the phase‐separation temperatures was poly(EOVE) (20 °C) < poly(EOEOVE) (41 °C) < poly(MOVE) (70 °C)] underwent multiple reversible transitions from sol (<20 °C) to micellization (20–41 °C) to physical gelation (physical crosslinking, 41–64 °C) and, finally, to precipitation (>64 °C). At 41–64 °C, the physical gel became stiffer than similar diblock or ABA triblock copolymers of the same molecular weight. Furthermore, the ABC triblock copolymers exhibited Weissenberg effects in semidilute aqueous solutions. In sharp contrast, another ABC triblock copolymer with a different arrangement, EOVE₂₀₀‐b‐EOEOVE₂₀₀‐b‐MOVE₂₀₀, scarcely exhibited any increase in viscosity above 41 °C. The temperatures of micelle formation and physical gelation corresponded to the phase‐separation temperatures of the segment types in the ABC triblock copolymer. No second‐stage association was observed for AB and ABA block copolymers with the same thermosensitive segments found in their ABC counterparts. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2601–2611, 2004     

Theoretical approach to cationic polymerization of alkenylfurans. II. Ab initio and semiempirical study of relevant steps in the reaction mechanism

SCF ab initio and AM1 semiempirical calculations with full geometry optimization have been carried out to model the initial steps of alkenylfuran cationic polymerization. Semiempirical procedures have been used to model propagation steps. Proton affinities of the relevant neutral species as well as the heats of formation of probable dimers were calculated. The results allow the explanation of the experimental behavior. The capabilities of the employed methods to describe these type of processes is discussed. It is confirmed that competition between vinyl and ring site attacks is the most important feature in these systems. © 1992 John Wiley & Sons, Inc.