Synthesis and characterization of magnetite dodecahedron nanostructure by hydrothermal method

Magnetite dodecahedral nanocrystals were fabricated using ethlenediamine tetraacetic acid (EDTA)-mediated hydrothermal route. Scanning electron microscopy images displayed that the products were almost dodecahedrons. The length of two different ribs were about 300 and 200 nm, respectively. X-ray diffraction patterns showed that the products were the cubic inverse spinel structure. Fourier transform infrared spectrum directly provided evidence of the EDTA bound to a specific surface of the precipitated magnetic nanocrystal.

Magnetic Mesoporous Silica Spheres for Drug Targeting and Controlled Release

Magnetically functionalized mesoporous silica spheres with different size (average diameter, A.D.) from 150 nm to 2 mu m and pore size distribution were synthesized by generating magnetic FexOy nanoparticles onto the mesoporous silica hosts using the sol-gel method. The X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), N-2 adsorption/desorption results show that these composites conserved regular sphere morphology and ordered mesoporous structure after the formation of FexOy nanoparticles. XRD and X-ray photoelectron spectroscopy (XPS) analysis confirmed that the FexOy generated in these mesoporous silica hosts is mainly composed of gamma-Fe2O3. Magnetic measurements reveal that these composites with different gamma-Fe2O3 loading amounts possess super-paramagnetic properties at 300 K, and the saturation magnetization increases with increasing Fe ratio loaded.

Impedance study of (PEO)(10)LiClO4-Al2O3 composite polymer electrolyte with blocking electrodes

A composite solid polymer electrolyte (SPE) of (PEO)(10)LiClO4-Al2O3 was prepared and Pt and stainless steel(SS) blocking electrodes were used for an impedance study. It was found that the semicircle in the high frequency range and the straight line in the low frequency range depend upon different blocking electrodes and polarization potentials applied in the experiments. In the equivalent circuit. two constant phase elements (CPE) have been used instead of the pure geometrical and double layer capacitances. respectively. A theoretical line calculated from their estimated values has a good correlation with the experiment data. Moreover. the equivalent circuit also can be used to explain the impedance properties of Pt and stainless steel (SS) blocking electrodes both in the high and the low frequency ranges. (C) 2001 Elsevier Science Ltd. All rights reserved.

CONFORMATION OF PHENYL RINGS IN THE HELICAL CHAIN POLYMER POLY(TRIPHENYLMETHYL METHACRYLATE)

The conformation of phenyl rings in the side groups of the helical chain polymer poly(tripenyl-methyl methacrylate) (1) in solution was studied by spectroscopic methods. According to the Raman spectrum the phenyl rings of 1 and triphenylmethyl methacrylate in solution have the same depolarization ratio at 1002 cm-1. The electronic spectra (ultraviolet and fluorescence) of 1 are similar to those of model substances, except for the "red shift" of the spectra of about 5 nm. It was concluded that the phenyl rings can rotate around the phenyl-C bond.

Origin and Pathway of Equatorial 13 degrees C Water in the Pacific Identified by a Simulated Passive Tracer and Its Adjoint

The origin and pathway of the thermostad water in the eastern equatorial Pacific Ocean, often referred to as the equatorial 13 degrees C Water, are investigated using a simulated passive tracer and its adjoint, based on circulation estimates of a global general circulation model. Results demonstrate that the source region of the 13 degrees C Water lies well outside the tropics. In the South Pacific, some 13 degrees C Water is formed northeast of New Zealand, confirming an earlier hypothesis on the water's origin. The South Pacific origin of the 13 degrees C Water is also related to the formation of the Eastern Subtropical Mode Water (ESTMW) and the Sub-Antarctic Mode Water (SAMW). The portion of the ESTMW and SAMW that eventually enters the density range of the 13 degrees C Water (25.8 < sigma(theta) < 26.6 kg m(-3)) does so largely by mixing. Water formed in the subtropics enters the equatorial region predominantly through the western boundary, while its interior transport is relatively small. The fresher North Pacific ESTMW and Central Mode Water (CMW) are also important sources of the 13 degrees C Water. The ratio of the southern versus the northern origins of the water mass is about 2 to 1 and tends to increase with time elapsed from its origin. Of the total volume of initially tracer-tagged water in the eastern equatorial Pacific, approximately 47.5% originates from depths above sigma(theta) = 25.8 kg m(-3) and 34.6% from depths below sigma(theta) = 26.6 kg m(-3), indicative of a dramatic impact of mixing on the route of subtropical water to becoming the 13 degrees C Water. Still only a small portion of the water formed in the subtropics reaches the equatorial region, because most of the water is trapped and recirculates in the subtropical gyre.

中国海蓝子鱼科Family Siganidae分类和动物地理学特点

蓝子鱼科鱼类隶属于鲈形目、刺尾鱼亚目，广泛分布于我国东海、南海及台湾海域。本文根据中国科学院海洋研究所多年来在我国海域采集并收藏的以及部分补充采集的蓝子鱼标本，参考国际最新研究资料，对我国海域蓝子鱼科鱼类进行分类和动物地理学研究，共记录中国海域蓝子鱼科鱼类1属2亚属11种。经研究分析，得到如下结论： 1.中国沿海蓝子鱼科鱼类的多样性问题。国内曾有13种蓝子鱼的分布记录，其中蠕纹蓝子鱼Siganus vermiculatus和暗体蓝子鱼S. punctatissimus仅以前的学者做过名录形式的记载，并无标本收藏，本文中不做介绍。此外尖嘴蓝子鱼Siganus unimaculatus也可能存在于中国海域，有待于进一步研究。目前确定在中国海域有分布的蓝子鱼为11种，约占世界总种数（27）的40％多，种的多样性较高。 2. 形态学比较研究说明，蓝子鱼在体形、体色、牙齿、头骨、椎骨、耳石等特征方面存在种间差异，可作为蓝子鱼科鱼类分类的有效鉴别特征。对于外部形态极其相似的种，可借助内部解剖特征相辅助予以区分。 3．对蓝子鱼动物地理学特点研究分析结论如下：a.中国海域存在的11种蓝子鱼在印度－太平洋海域均有分布，没有地方特有种。b.长鳍蓝子鱼和褐蓝子鱼在我国东海、台湾海域和南海均有分布，褐蓝子鱼在黄海北部亦有分布，种群数量较大；其它9种，除凹吻蓝子鱼仅分布于南海外，均分布于南海及台湾海域，种群数量较小。c.中国海域蓝子鱼种类组成与邻近的菲律宾、马来西亚、印度尼西亚海域比较相似，中国分布的种类在这些海域均有分布，且分布于这一区域而中国没有记录的有5种。与日本相比，种类组成也比较相似，中日共有种达9种，仅分布于中国海域2种，仅分布于日本海域1种。 4. 作者参照国际最新研究结果和较为公认的分类系统Nelson（1994），将蓝子鱼科置于刺尾鱼亚目，而不再使用国内学者长期惯用的蓝子鱼亚目。蓝子鱼科包括一属蓝子鱼属Siganus Forsskål, 1775，两亚属：蓝子鱼亚属Siganus Forsskål, 1775 和罗蓝子鱼亚属 Lo Seale, 1906，同时使全部种名的变动和确定与国际最新研究结果(Woodland, 1990; 2001）取得一致。

21世纪智能机器人发展预测

智能机器人是作为扩大计算机的功能和人工智能的实验床而形成和发展起来的.80年代中期基于感觉控制的智能机器人进入实用阶段.90年代将以装配机器人为先导产品,以电子、电气、精密机械制造为先导应用产业普及,特种机器人也将取得突破性的进展.本文对21世纪的下一代机器人的单元技术,应用领域及其前景作了预测.

非均匀性对岩石破裂过程影响的研究

Rock heterogeneity plays an important role in rock fracturing processes. However, because fracturing is a dynamic process and it is very difficult to quantify materials' heterogeneity, most of the theories dealing with local failure were based on the homogeneity assumption, very few involving stress distribution heterogeneity and successive local failure due to rock heterogeneity. Therefore, based on various references, the author studied the laws and mechanism of influences of heterogeneity on rock fracturing processes, under the frame of the project "Study on Associate Mechanism between Rock Mass Fracture and Strength Failure", funded by Nation Natural Science Fund. the research consists of such aspects as size effect correction to rock fracture parameters, SEM (Scanning Electron Microscope) real-time observation on rock samples under different loads, micro-hardness testing, and numerical simulating based on microstructure. There are some important research results as followed: 1. Unifying formula for nonlinear and non-singularity correction, simplifying the complex process of correcting size effect on rock fracture toughness. 2. Using the methods of micro-hardness testing mineral grain and random jointing micrograph digitizing mineral slice, preliminarily solving the problems of numerical simulating and quantitatively describing the heterogeneous strength and its distribution rules, which has certain innovation and better practicability. 3. Based on SEM real-time observation, studying the micro-process of fracturing in marble, sandstone, granite, and mushroom stone samples with premanufactured cracks under tension, pure-shear and compression-shear conditions. Strength Failure was observed: there was some kind failure occurred before Fracture Failure in marble and sandstone samples with double cracks under pure-shearing. It is believed that the reason of strength failure developing is that stress concentrations is some locations are larger than that near the end of pre-manufactured cracks. 4. Based on the idea that rock macro-constitute is composed of complex microstructure, the promising method used to handle heterogeneity considers not only the heterogeneity of the rock medium, but also the heterogeneity of the rock structure. 5. Putting forward two types of rock strength failure: medium strength failure induced by heterogeneity of rock medium and structure strength failure induced by heterogeneity rock structure. 6. By evaluating potential fracture cell with proper failure priority, the numerical simulating method solved the problem of simulating the coextensive strength failure and fracture failure with convention strength failure rules. The result of numerical analysis shows that the influence of heterogeneity on rock fracturing processes is evident. The sinuosity of the rock fracture-propagation path, and the irregular fluctuation of loading displacement curve, is mainly controlled by the heterogeneity of rock medium.

垃圾填埋场渗滤液中的汞及现场污水处理设施对其的去除

渗滤液一直是困扰垃圾填埋场的一个主要问题，处理不当会对周围生态环境造成严重的污染。垃圾中混入的汞淋滤进入渗滤液将会造成水体的汞污染。对贵阳市高雁垃圾卫生填埋场产生的渗滤液原液和不同处理单元过程中汞的含量进行了调查分析，结果表明该填埋场渗滤液原液中的汞含量为79.4ng·L^-1，处于国内外的中低水平，就汞而言污染并不严重。经过处理，渗滤液有近2／3的汞被去除了。渗滤液原液中的汞主要以颗粒态为主，随着处理单元过程，这一比例逐渐降低。渗滤液中的汞含量与填埋垃圾汞含量、pH、以及填埋物质对汞的吸附有关.