稠油分散体系中黏度与化学组成的灰熵关系分析

采用灰色关联熵分析法研究了稠油黏度及其族组成、有机杂原子、金属元素和主要官能团的关联,探讨了物系黏度随稠油分散系统微观结构的变化规律.结果表明:①沥青质是影响稠油黏度的最主要的因素,稠油体系中沥青质聚集分相的形成特性取决于稠油体系的物理结构,即稠油胶体构造的稳定性.胶体稳定性越高,沥青质越不容易从稠油分散体系中聚集沉淀.②在沥青质分子单元叠积过程中,由沥青质的杂原子因素、过渡金属因素、芳香环结构因素和脂肪性侧链因素共同决定的化学作用的影响是第一位的,其中芳香环结构因素和杂原子因素的影响最为显著,而由稠油体系不稳定性构成的物理作用的影响则居于次要地位.     

Chemical analysis of size-tailored magnetic colloids using slurry nebulization in ICP-OES

In this work, inductively coupled plasma emission spectroscopy was utilized to directly determine the chemical composition of magnetic fluids constituted of size-sorted ferrite nanoparticles in aqueous solution. Nickel and cobalt nanoferrites were chemically synthesized following a bottom-up route and dispersed under various pH conditions. Size and structural characteristics of nanograins were investigated by X-ray diffraction using a synchrotron source. Chemical analysis was then carried out by directly introducing diluted magnetic fluid samples (slurries) into the spectrometer. To achieve reliable measurements, sample conditions and apparatus parameters were carefully investigated. Slurry stability must be optimized in order to obtain reproducible and accurate analysis. The instrument must also be calibrated to minimize the difference between the signal produced by slurries and that of aqueous ordinary solutions. Furthermore, slurry sample introduction offers many advantages over conventional sample digestion, including reduced sample pretreatment time, less possibility of contamination and the use of direct calibration with aqueous solutions.     

Water-dispersible hydroxyapatite nanorods synthesized by a facile method

A simple and effective method, using calcium nitrate and triammonium phosphate as starting materials, for the preparation of water-dispersible hydroxyapatite nanorods (HAp) was reported. The process primarily involves the preparation of HAp with the addition of sodium citrate (NaC) and the exchange of absorbed ions (NaC) with sodium hexame taphosphate (NaP). The end products were investigated using various means in order to confirm the particles’ crystal phase and morphology and to understand how to improve their stability. The results demonstrate that the resulting HAp at 90 °C is rod-like with length of 300-400 nm and width of 40-60 nm. The zeta potential values of pure HAp, HAp-NaC, HAp-NaC/NaP are from −15.20, −30.89 to −44.84 mV. The settling time test shows the HAp-NaC/NaP could keep stable above 7 months without any creaming or visible sedimentation. The amount of NaC and the reaction temperature play significant roles in the whole process due to the formation of Ca containing precipitates.     

PMMA colloid particles armored by clay layers with PDMAEMA polymer brushes

Poly[2‐(dimethylamino) ethyl methacrylate] (PDMAEMA) brushes on the surfaces of clay layers were prepared by in situ free‐radical polymerization. Poly (methyl methacrylate) (PMMA) colloid particles stabilized and initiated by clay layers with PDMAEMA polymer brushes were prepared by Pickering emulsion polymerization. Transmission electron microscopy was used to characterize the structure and morphology of the colloid particles. The X‐ray diffraction (XRD) results indicated that the intercalated structures of the clay layers were almost destroyed in Pickering emulsion polymerization, and clay layers with exfoliated structures were created. The surface of the colloid particles was analyzed by using X‐ray photoelectron spectroscopy (XPS). The XPS results provide direct evidence that the clay layers with PDMAEMA chains cover the PMMA colloid particles. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 2632–2639, 2008     

纳米荧光粒子YVO_4∶Eu的合成及其在指纹显现中的应用

以柠檬酸为络合剂,在水相中合成了悬浮稳定性较好的稀土YVO4∶Eu溶胶,采用XRD、TEM、荧光光谱等技术,研究了稀土荧光粒子的尺寸、形貌、晶胞参数及发光性能.结果表明合成的YVO4∶Eu荧光粒子为四方晶系,粒径约为10nm,分散性较好;在pH=9.0时合成的Y0.7VO4∶Eu0.3溶胶具有最大的荧光强度,其最大发射峰在619nm;经乙二胺四乙酸二钠表面修饰后的Y0.7VO4∶Eu0.3纳米荧光粒子能够清晰地显现出光滑客体上的指纹,颜色为红色.     

The influence of long range interparticle correlations on the magnetically induced optical anisotropy in magnetic colloids

In this paper we develop a theoretical model for the magnetically induced optical anisotropy in dense magnetic colloids made of spherical and un-aggregated magnetic monodomain nanoparticles. Both dipole-field and dipole-dipole magnetic and electric interactions between the magnetic monodomain particles are taken into account in the Hamiltonian of the system. Using the pair correlation function in a colloidal suspension of magnetic nanoparticles developed by Ivanov and Kuznetsova (2001) [11], the complex dielectric constant of a magnetic colloid is modeled as a function of the light polarization direction, the magnetic field intensity and magnetic particle concentration and diameter. The two main features of the model are that, on the one hand, it predicts the possibility of magnetically induced optical anisotropy in dense magnetic colloids made of spherical and un-aggregated monodomain nanoparticles, and on the other hand, unlike the existing models for diluted samples, it predicts a non-linear dependence of dichroism and birefringence on magnetic particle concentration.     

Light scattering by nanosized systems with different spatial organizations

The integrodifferential equation method is used to study the spectrum of a nanoparticle colloid for the example of interaction of three arbitrarily arranged dielectric particles made up of nonresonant atoms (the eigenfrequency of the transition is far from the emission frequency) with incorporated barium atoms in an external optical radiation field. The effect on the light-scattering properties of a nanosphere in the ensemble of its distant “neighbors” is studied; an additional peak associated with them is observed as a frequency close to the resonance for an isolated nanosphere, which under certain conditions has higher intensity than the main peak corresponding to optical near-field resonance in a two-particle system. The dependence of the spectrum of the nanosized system on the geometric structure is studied, and it is shown that very precise tuning of the resonance frequency is possible by varying the angular distribution of the particles. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 641–646, September–October, 2006.     

Fe(OH)3胶体电泳实验的两则改进

Fe(OH)3胶体电泳实验最大的问题在于胶体纯化时间太长，利用电渗析法代替传统渗析法来纯化Fe(OH)3胶体，大大缩短了纯化时间和节省了蒸馏水。另外，在拉比诺维奇－付其曼U型电泳仪^[1]的基础上加以改进，使之更加合理。     

Preparation of cationic latices comprising hollow thermostable particles

A method is described for the preparation of cationic latices comprising submicron hollow particles for a possible application as a thermally stable polymeric pigment in coatings or pigmented compositions on the basis of thermosetting polymers cured at temperatures up to 170–190 °C. The method is based on the deposition of melamine–formaldehyde resin in the form of cationic colloid onto anionic hollow particles resulting in the recharging of anionic hollow particles and the formation of an outer melamine shell, which provides thermal stability of the hollow particles at curing and application of pigmented coatings and compositions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2225–2234, 2004     

Characterization of aluminum–organic‐stabilized platinum–colloid networks with electron and photon spectroscopies

We have measured and interpreted the ultraviolet (HeI) and X‐ray photoelectron spectra and the metastable impact electron spectra (MIES) from aluminum–organic‐stabilized platinum–colloids and colloid networks, deposited on silicon substrates and characterized by X‐ray photoelectron spectroscopy, scanning Auger electron microscopy and transmission electron microscopy. MIES, in particular, gives information on the electronic structure of the spacer molecules interconnecting the colloids. In addition, changes in the electronic structure of the platinum clusters that are induced by different spacer molecules were identified by means of X‐ray absorption near‐edge structure measurements at the platinum L_III‐edge of these materials. This combination of techniques was also employed to follow the chemical changes that occur upon heating of the network in situ. It turns out that the thermal decomposition of the network is driven by the disintegration of the spacer molecules. Moreover, less sintering of the colloidal particles occurs in the networked systems than in unconnected particles. Most of the networked platinum–particles are still present in their original shape even after the destruction of spacer molecules. This observation could be linked to the encapsulation of these platinum particles into an (Al? O) protecting shell. Copyright © 2003 John Wiley & Sons, Ltd.