1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

The behavior of suspensions and macromolecular solutions in crossflow microfiltration

Issues concerning powder consolidation methods compatible with the colloidal approach and issues associated with other powder processing steps, viz., densification and microstructural control, are presented with regard to research directions leading to more reliable ceramics.

Powder Processing Science and Technology for Increased Reliability

The recently published points of zero charge of metal oxides and related materials are compiled to update the previous compilation. The purity of materials is the most important factor responsible for discrepancies in the literature data. In contrast to the success of new spectroscopic methods in the studies of specific adsorption, the progress in studies of primary surface charging of oxides over recent years is less spectacular.

The pH-dependent surface charging and the points of zero charge.

Publisher Summary It is noted that colloidal particles can be effectively transported through subsurface porous media under certain hydrogeochemical conditions. If present in large concentrations, mobile colloids can act as carriers for strongly sorbing contaminants and thereby provide an unretarded transport pathway for contaminants that are otherwise strongly retarded. This potential transport pathway can be considered in risk assessments of sites heavily contaminated with toxic chemicals, such as certain radionuclides, heavy metals, and hydrophobic organic compounds. The chapter reviews the current state of knowledge about the behavior of colloids in porous media and their role in contaminant transport. The chapter also identifies some important future research needs. Colloids are commonly defined as small particles or other entities with dimensions roughly between 1 nm and 1 μm. These size limits to dissolved molecules on one side and to larger suspended particles on the other side. Colloidal particles remain stable in suspension over long time periods, unless they coagulate to form larger aggregates or deposit onto surfaces of larger grains.

Mobile Subsurface Colloids and Their Role in Contaminant Transport

Laminar flow in channels with porous walls

Identification of the fragmentation mechanisms in wet-phase fine grinding in a stirred bead mill

Prediction of the product size distribution in associations of stirred bead mills

A semiautomatic image analysis method, with minimal operator intervention, has been developed to characterize the morphology of yeast cells under the assumption that they have an ellipsoidic shape. The cells are observed by optical microscopy and the surface and the minor and major half-axes of the projection of the ellipsoid on the image plane are determined. Using this method, yeast size distributions and population kinetics (single and budding cells, cell clusters) are determined during alcoholic fermentations. Combination of image analysis with a methylene blue viability test is examined but the staining procedure induces a change in the size of the cells. .

Morphological characterization of yeast by image analysis

In order to determine the operating conditions leading to a product with a given particle size distribution, a study has been made of the influence of the operating parameters (stirrer speed, solids concentration, beads diameter) on the particle size distribution of the product obtained in wet fine grinding in a stirred bead mill. Combination of the results of this study with a flow model through the mill leads to a model of the continuous grinding process. This model suggests that the spreading of the particle size distribution could be reduced either in multiplying the number of mills associated in series, nor in multiplying the number of passages through the same mill. Experiments made with the same overall residence time confirm this assumption.

John Dodds

Papers

Laminar flow in channels with porous walls

Identification of the fragmentation mechanisms in wet-phase fine grinding in a stirred bead mill

Prediction of the product size distribution in associations of stirred bead mills

Morphological characterization of yeast by image analysis

Prediction of the product size distribution in associations of stirred bead mills