Progress on phthalocyanine-conjugated Ag and Au nanoparticles: Synthesis,characterization, and photo-physicochemical properties

Phthalocyanine (Pc) complexes are an important class of dyes with numerous (e.g., biological, photophysical, and analytical) applications. Among the methods used to improve the properties of these complexes, one should mention the introduction of different substituents, variation of the central metal ion, ligand exchange, and conjugation to nanomaterials (e.g., carbon-based nanomaterials and metal nanoparticles (NPs)). This work briefly reviews Pc complex conjugation to Ag and Au NPs, highlights the different NP shapes, and discusses the diversity of conjugation approaches. Moreover, the use of UV–Vis spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, atomic force microscopy, dynamic light scattering and Fourier transform infrared spectroscopy to characterize Pc-NP hybrids is summarized. The effect of conjugation on Pc photo-physicochemical properties (fluorescence, singlet oxygen generation, triplet state formation, and optical limiting behavior) is discussed, and future perspectives for the synthesis and applications of new hybrids are provided.     

Characterization of thermo-oxidative stability of polymer optical fibers using chemiluminescence technique

The thermo-oxidative stability of commercially available polymer optical fibers (POFs) and their components (cores and claddings) was investigated. All the bare POFs (core and cladding only) studied here were based on poly(methyl methacrylate) (PMMA) core. The fibers were exposed to 100 °C/low humidity for about 4200 h. Chemiluminescence (CL) technique was applied to investigate the thermo-oxidative stability and for measuring the transmission loss during exposure a prototype device called multiplexer was used. POFs exhibited variation in thermo-oxidative stability although they possessed identical core material PMMA. This was due to difference in the chemical compositions of claddings. Claddings were more susceptible to the thermo-oxidative degradation compared to cores. The thermo-oxidative degradation of both the cladding and the core was found in POFs as a result of climatic exposure. POFs showed an early drop-off followed by a slow decline of transmission. The early drop-off of transmission was attributed to physical changes like thermal expansion and the slow decline of transmission to chemical changes like oxidative degradation of POFs. A good linear relationship between optical transmission stability and thermo-oxidative stability of POFs was established from these studies.     

溴碘化银薄片乳剂颗粒中碘离子分布对潜影分散的影响

碘溴化银乳剂薄片颗粒的潜影分散与碘离子在颗粒中的分布有关。本文用交叉光楔曝光技术测定了由次潜影造成的潜影分散,并根据所测出的潜影分散度和乳剂的表面感光度,对内、表敏的分布作了分析。结果表明,碘离子分布在颗粒边缘的乳剂,其表面潜影分散度要比碘离子均匀分布的颗粒更甚,后者且表现出内、表敏度竞争的现象。     

量化方法研究分子结BEMP和TEMP的电子输运特性

通过结合杂化密度泛函和前线轨道理论与弹性散射格林函数方法研究了BE- MP(benzene-1,4-di-ethynyl-4-mercaptophenyl)和TEMP(thiophene-2,5-di-ethynyl-4- mercaptophenyl)两分子结的输运性质。基于杂化密度泛函方法计算两扩展分子电子结构的基础上,计算了两分子的输运性质．计算结果显示:电流增加来源于电极和分子轨道的共振;电导曲线呈现出平台特征．在此基础上从扩展分子A(Au-BEMP-Au)中间的苯环的旋转而引起电流减小的角度解释了负微分电阻现象．     

岩石的核磁共振自旋密度微成像

岩，心是油气储层的基本单元，其内部结构和渗流性质反映了油藏的基本特征．岩。心的精细描述是油藏描述、储层动态监测及设计强化采油方案的重要基础．本文利用核磁共振（NMR）自旋密度做成像，快速无损地观测到两类基本储油岩石——砂岩和灰岩的内部结构，提供了岩石渗透性、孔隙性及灰岩沉积环境等重要信息．1实验方法以自旋回波单片NMR成像脉冲序列为基础，设。P平面内样品的目施密度为P（。，v）．演化期t。，在。方向梯度场G。作用下，各处横向磁化矢量获得的相移为式中，7为共振核（在成像中一般为质子）的旋磁比，g为坐标位置·…     

Structural and Chemical Analysis of Materials with High Spatial Resolution

 An understanding of the correlation between microstructures and properties of materials require the characterization of the material on many different length scales. Often the properties depend primarily on the atomistics of defects, such as dislocations and interfaces. The different techniques of transmission electron microscopy allow the characterization of the structure and of the chemical composition of materials with high spatial resolution to the atomic level: high resolution transmission electron microscopy allows the determination of the position of the columns of atoms (ions) with high accuracy. The accuracy which can be achieved in these measurements depends not only on the instrumentation but also on the quality of the transmitted specimen and on the scattering power of the atoms (ions) present in the analyzed column. The chemical composition can be revealed from investigations by analytical microscopy which includes energy dispersive X-ray spectroscopy, mainly quantitatively applied for heavy elements, and electron energy-loss spectroscopy. Furthermore, the energy-loss near-edge structure of EELS data results in information on the local band structure of unoccupied states of the excited atoms and, therefore, on bonding. A quantitative evaluation of convergent beam electron diffraction results in information on the electron charge density distribution of the bulk (defect-free) material. The different techniques are described and applied to different problems in materials science. It will be shown that nearly atomic resolution can be achieved in high resolution electron microscopy and in analytical electron microscopy. Recent developments in electron microscopy instrumentation will result in atomic resolution in the foreseeable future.     

Field-induced structural ordering in electrorheological fluids

Structural relaxations of an electrorheological fluid (ERF) due to changes in the applied electrical field strength or shear rate are observed on time scales 1 s<t<40 000 s. Commercial ERFs consisting of mesoscopic polyurethane particles in a silicone oil matrix were studied by three different experimental techniques in order to obtain and compare the characteristic relaxation times. It is demonstrated that dielectric spectroscopy, viscosimetry and light transmission experiments represent the same results concerning the structural relaxation phenomena of ERFs when electrical fields are applied. The tendency of strong induced dipoles to align the particles in the direction of the field increases the effective dipole moment and therefore , the shear viscosity and the amount of light transmitted along the field direction in an ITO/glass sandwich cell. The optical experiment is capable of resolving fast processes within the first 1 ms if large electrical fields are applied. The effects of electrophoresis and shearing, which both counteract the field induced structures, are also addressed.     

不共轴光学系统自动优化中的有关问题

描述不共轴光学系统计算机优化中坐标变换与逆变换、“入瞳”与光线坐标、像面基准与质量函数定义的一致性问题。