Molecular dynamics simulation of the forces between colloidal nanoparticles in Lennard–Jones and <Emphasis Type="Italic">n</Emphasis>-decane solvent

Molecular-dynamics is utilized to simulate solvation forces between two nanoparticles immersed in two different solvents: Lennard–Jones spheres and and n-decane. Three different sizes and shapes of solvophilic nanoparticles are investigated. Nanoparticles in the Lennard–Jones liquid exhibit solvation forces that oscillate between attraction and repulsion as the nanoparticle separation increases. The magnitude of these solvation forces increases with particle size and depends on particle shape, consistent with the Derjaguin approximation. When n-decane is the solvent, the solvation forces are negligible for small nanoparticles, with sizes comparable to the end-to-end distance of all-trans decane. The solvation forces oscillate between attraction and repulsion for sufficiently large nanoparticles in decane—however the Derjaguin approximation does not appear to be effective at describing the dependence of nanoparticles forces on nanoparticle size and shape when decane is the solvent. For both the Lennard–Jones and n-decane solvents, it is apparent that the force profiles are influenced by the surface roughness of the nanoparticles. These factors should be taken into account in efforts to engineer colloidal suspensions.     

辽河超稠油减粘裂化工艺研究

在自制小型连续减粘裂化装置上 ,对辽河超稠油进行了减粘裂化的工艺研究。考察了辽河超稠油在 370～ 41 0℃和 1～ 3h停留时间条件下超稠油粘度变化情况。实验数据表明 :在本研究范围内 ,辽河超稠油主要进行裂化反应 ,缩合反应较少 ;粘度可达 2 0 0 # 燃料油的要求 ,还可得 1 5 %～ 1 7%的轻质油品 ;限制超稠油减粘裂化反应深度因素不仅仅是焦炭的生成 ,而且还有稠油胶体体系的破坏。     

Adhesion of Nanoparticles Fouling Glass Surfaces

The fouling of glass surfaces by nanoparticles formed from corroding iron was studied. Simple experiments demonstrated that adherent films of nanoparticles were deposited by corrosion of iron particles on a glass surface and by flowing water past corroding particles and then onto a glass surface. The water collected from this experiment was found to contain about 2 parts per million (ppm) of particles 500 nm in diameter when tested by photon correlation spectroscopy. However, electron micrographs showed that the primary particles in the fouling film were 20 nm in diameter. This discrepancy was explained by a new theory of nucleation of the fouling films. The theory was confirmed by measuring the particle size of ferric hydroxide dispersions as a function of concentration and pH. It was shown that the 20 nm primary nanoparticles nucleated much larger stable aggregates (defined as nucleags), which were sensitive both to pH and to magnetic fields. In particular, as the pH rose above 6, flocculation occurred, and large unstable agglomerates were observed. The conclusion was that three types of particle could exist in the corrosion product of iron and water: nanoparticles, nucleags, and flocs.     

表面电位及中性油的分散度对矿粒与油滴之间作用能的影响

本文根据胶体与表面化学理论研究了表面ξ—电位及中性油的分散度对辉钼矿、石墨、滑石等天然疏水性矿粒与油滴之间作用总能的影响。     

Capillary force assembly of giant vesicles on a microstructured substrate

Convective capillary force assembly has shown to efficiently assemble nm to μm solid colloids onto a surface. We show here that this technique can also efficiently trap liposomes with 10 μm mean size or films of lipid into microstructures. We hypothesize that whether liposomes or lipids are trapped in the template depends on the interfacial interaction of the objects with the surface. After solvent evaporation, ruptured and deflated liposomes are observed onto oxidized (hydrophilic) PDMS while uniform films of lipids are found in untreated (hydrophobic) PDMS microstructures. This assumption is supported by the analysis of the evaporation of a droplet containing a dispersion of liposomes in free environment.     

Colloid dispersion on the pore scale

Dispersion describes the spreading of a tracer or contaminant in an aquifer. Detailed knowledge of dispersion is the key to successful risk assessment in case of groundwater pollution or groundwater protection. The dispersion of colloids on the pore scale is controlled by flow velocity, ionic strength, colloid size, colloid concentration, and colloid-matrix interactions. The objective of this study was to provide quantitative data and to assess the scale dependency of colloid dispersion on the pore scale. The positions of carboxylated polystyrene microspheres (1 μm, 0.5 μm) were recorded during transport experiments in silicon micromodels with three pore topologies. The positions were combined into particle trajectories revealing the flow path of individual colloids. More than thousand trajectories were evaluated for each experiment to obtain the dispersivity of the colloids for flow distances between 10 and 1000 μm. All experiments were run at high Peclet numbers. The pore scale dispersivity was on the order of 8-30% of the flow distance with pure water, dependent on the heterogeneity of the pore topology. The dispersivity was positively correlated with the ionic strength and inversely correlated with the colloid size and the flow velocity. A coating of the micromodel surface with humic acid also increased dispersivity. The quantitative data set presented here supports the theoretical framework for colloid transport and allows to parametrize colloid transport on the pore scale.     

改性钠磷酸盐无机树脂铸造粘结剂性能研究

通过采用H^＋对简单钠磷酸盐进行改性，获得了一种高稳定性的呈胶体状态的复合钠磷酸盐基粘结剂，并引入Al^3＋、Mg^2＋、B^3＋金属离子改性以提高其抗吸湿性。在较低温度下，H^＋、Al^3＋、Mg^2＋、B^3＋复合改性钠磷酸盐粘结剂砂（芯）型溃散性较好。     

A proximity-based image-processing algorithm for colloid assignment in segmented multiphase flow datasets

Colloidal transport and deposition are of both environmental and engineering importance. Easier access to x-ray microtomography (XMT) coupled with improved imaging resolution has made XMT a unique and viable tool for visualizing and quantifying these processes. Currently, there is scant information in the literature addressing colloid segmentation and analysis in saturated and unsaturated porous media, in particular related to spatial partitioning of colloids. To support this need, an approach to assign segmented colloidal particles and aggregates to different partitioning classes based on their proximity to different phases is presented here. The method uses different markers for each attachment site (e.g. wetting-nonwetting phase interfaces). An example XMT dataset from a drainage experiment is used to demonstrate the efficacy of the image processing algorithms. Flow conditions, and fluid and colloid properties, can thus be compared to the behaviour of colloids within the porous medium. This algorithm can help elucidate colloidal deposition mechanisms and the importance of different attachment sites, explore the importance of fluid properties, as well as the arrangement and shape of the colloids.     

凝胶—沥青复合粘结剂制备少烟害炭素电极初探

采用沥青作粘结剂生产炭素电极,生产过程中产生大量沥青烟气。本文用凝胶—沥青复合粘结剂研制成一种新型少烟害炭素电极,并对其主要物理性能作了测试分析。结果表明,该种炭素电极性能较好,为减少生产过程中的烟害开辟了一条新途径。     

Incorporated Organic Modified Ag Nanoparticles in Ormocer

Ag nanoparticles coated trisodium citrate were incorporated in ormocer by sol-gel method. The doping concentration of Ag in ormocer is about 1.0% in weight. The HRTEM demonstrated that the particles disperse in ormocer, and the size of Ag nanoparticles is 5-10 nm. The absorption band of Ag nanoparticle at 410 nm was observed.