钙钛矿型复合氧化物LaNi_(1-x)Mn_xO_3晶体结构与催化性能的关系

用XRD、IR和TPR等技术研究了钙钛矿型复合氧化物的晶体结构及其反应性能.整个组成范围内,LaNi_(i-x)Mn_xO_3(0.0≤x≤1.0)体系都生成单一钙钛矿相;x=0.0,0.6≤X≤1.0时为菱形晶系,0.2≤x≤0.5为立方晶系.IR和TPR研究表明,晶体结构对B—O键合作用存在较大影响.CO微反考察表明,本体系的催化活性与晶系存在密切关系,晶体对称性越高,反应活性越低.说明钙钛矿型复合氧化物的催化活性与体系活性中心的B—O键合作用能力有关.     

方位偏振 Be s s e 一 Ga u s s光束的传输特性研究`

利用 o C il sn 衍射积分公式,给出了方 位偏 振 e B s el一G au s 光 束通过 A B C D 轴 对称 光学系统的解析 表达式.对其通过 自由空 间和付里 叶变换系统特殊情况的传输作 了分析和 讨论.     

关于一类六角系统的共振多项式

本文揭示了单洞 Cata 型六角系统的共振多项式与广义冠的匹配多项式的关系、将1977年 Gutman 提出的方法推广应用到有洞的六角系统,并得到一些共振多项式的比较定理.     

一种动态实时的遥感专题应用系统定制框架

遥感专题应用系统广泛用于遥感影像的加载、分析、专题提取、出图等.为实现遥感专题应用系统动态、实时和可扩展的定制化开发,设计了一套基于组件的遥感专题应用系统定制框架：定义了组件划分方式,将专题系统划分为功能类组件和容器类组件,建立了组件属性和组件间的关系;采用XML文件描述遥感专题应用系统中的组件,并提供从XML到遥感专题应用系统的解析方法;设计了遥感专题应用系统定制平台,提出一种动态实时的软件设计方法,可以“所见即所得”地定制遥感专题应用系统,并将其保存为XML文件.采用该定制平台定制的多个专题系统已应用于相关部门.该框架为快速高效定制遥感专题应用系统提供了一种新的开发设计模式,降低了遥感数据在多行业应用的技术门槛,减少重复性开发工作.     

Instrument for generation of volatile organic compounds for the development of chemical sensors and evaluation of tube-type diffusive sampling

An automatic calibration apparatus for the dynamic generation of organic vapours was developed. The accurately controlled stream of nitrogen was drawn at a low flow-rate through a thermostated container filled with the standard substance, thus generating a continuous stream of saturated vapour of the compound. The compound holder vessel was thermostated at −16°C. A large stream of pure carrier gas was mixed with a low stream of substance in a mixing chamber for dilution. The fittings were manufactured from PTFE, and tubes were made of special PTFE with an inert inner surface to eliminate the wall adsorption and to decrease the cross-diffusion. Moisture interferences were reduced using a Nafion membrane filter. The vapour generator was validated by diffusive sampling and gas chromatographic methods. Standard mixtures have been prepared containing toluene at concentrations ranging from 3 to 3000 ppm. The combined uncertainty of preparative and analytical error components associated with the concentration of the analytes at the 95% confidence level typically ranges from 2 to 5% relative, depending upon the concentration. The measured and the calculated values were compared and good correlation (r²>0.99) was found.     

Calorimetric study of molecular superconductor κ-(BEDT-TTF)<Subscript>2</Subscript>Ag(CN)<Subscript>2</Subscript>H<Subscript>2</Subscript>O which contains water in the anion layers

Thermodynamic investigation of an organic superconductor κ-(BEDT-TTF)₂Ag(CN)₂H₂O in which the BEDT-TTF dimers are arranged in the κ-type structure in the donor layers is performed by the relaxation calorimetric technique at low temperatures and under magnetic fields. A thermal anomaly related to the superconductive phase transition was observed at 5 K. The existence of residual γ^* in the superconductive state is about 18% of the normal state γ value, which is larger than those of κ-(BEDT-TTF)₂Cu(NCS)₂, and κ-(BEDT-TTF)₂Cu[N(CN)₂]Br salt. The lattice heat capacity reflected on the β-term in the low-temperature heat capacity was found to be affected by the cooling rate. The disorder produced in the network structure constructed by hydrogen bond in the insulating layer is considered to give low-energy phonon excitations reflected in the heat capacity.     

Ionic and excited intermediates in pulse-irradiated polypropylene doped with aromatics

A pulse radiolysis study of isotactic polypropylene (PP) film has been carried out with the main aims of investigating charge trapping in an undoped system and solute radical ion generation in an pyrene (Py) doped matrix. In PP, pulse radiolysis gives electron–positive hole pairs. The electron can be stabilized in the undoped system as a trapped electron, e. The transient absorption spectrum of e in the near-IR (up to 1800 nm) was observed in the temperature range 30–100 K. This IR absorption was not detected in the case of oxidized PP. In such a matrix electrons can be scavenged by oxidation products generating respective radical-anions (absorption in the UV RANGE, λ < 350 nm). In a doped matrix transient absorption bands centered at 450 and 500 nm were observed which can be assigned to the Py radical cation and anion, respectively. The recombination of these ionic species leads to monomer excited-state formation observed during and after the 17 ns pulse. Contrary to the Py-doped polyethylene no excimer emission was detected at room temperature even if Py content in PP was close to 0.02 mol dm⁻³. The rate of Py radical-ion decay was found to be temperature dependent. Two linear parts of the Arrhenius plot were observed which intersected at ca. 240 K, the glass transition temperature, T_g, for PP. The activation energies calculated for two parts of Arrhenius plot were equal to 111 and ca. 0.78 kJ mol⁻¹ for T > T_g and T < T_g, respectively. Some preliminary results concerning the ionic processes in PP containing two solutes (Py, 3,3′-dimethyldiphenyl) were presented. The mechanism of ionic recombination in PP will be proposed and discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1217–1226, 1998     

NOVEL pH-SENSITIVE DRUG DELIVERY SYSTEM BASED ON NATURAL POLYSACCHARIDE FOR DOXORUBICIN RELEASE

A novel pH-sensitive nanoparticle drug delivery system (DDS) derived fl'om natural polysaccharide pullulan for doxorubicin (DOX) release was prepared.Pullulan was functionalized by successive carboxymethylization and amidation to introduce hydrazide groups.DOX was then grafted onto pullulan backbone through the pH-sensitive hydrazone bond to form a pullulan/DOX conjugate.This conjugate self-assembled to form nano-sized particles in aqueous solution as a result of the hydrophobic interaction of the DOX.Tr...     

Confined systems and the modified virial theorem from semiclassical considerations

We show that two simple semiclassical strategies, one based on the Wilson–Sommerfeld rule and the other on the uncertainty principle, yield the exact modified form of the virial theorem for confined systems. An alternative, easier quantum mechanical route to arrive at this result is also sketched. Pilot calculations on confined oscillators reveal decisive trends. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Stopped-flow kinetic method for the fluorimetric determination of DNA traces in biological samples based on the interaction long-wavelength fluorophor, surfactant and nucleic acid

A simple and rapid method for the determination of DNA, involving the interaction between a surfactant, a long-wavelength fluorophor (LWF) and the nucleic acid, is presented. Different chemical systems based on the local effective charge of the surfactant/LWF system with DNA were tested, choosing cetyltrimethyl ammonium bromide (CTAB) and indocyanine green (ICG) for the development of the method. The fluorescence of ICG increases in the presence of CTAB, but it rapidly decreases in the presence of deoxyribonucleic acid. The initial reaction-rate (v₀) and signal at a prefixed-time (ΔIF₂₀) are monitored at 780 and 802 nm as excitation and emission wavelengths, respectively, using stopped-flow mixing technique, which makes the method applicable to automate routine analysis. Each measurement was obtained in about 30 s, being the integration time 0.1 s. The dynamic range of the calibration graph was 10-1500 ng mL⁻¹, with a detection limit of 5 ng mL⁻¹. The precision of the method, expressed as relative standard deviation, ranged between 2.1% and 4.5%. After a sample treatment consisting on a conventional extraction, the method was applied to the determination of DNA in several samples from different biological materials.