It has been known for a long time that both the crystal structure and kinetics of crystallisation can be affected by ultrasound. In the past systems used have relied on high power ultrasonic probes to produce crystals. The majority of these probes produce cavitation in the system and it has been difficult to differentiate between effects caused by the ultrasound alone or by the cavitation produced by ultrasound on the crystal structure. Some materials, such as fats, are very susceptible to the production of free radicals that lead to "off-flavours" being obtained. These "off-flavours" are easily produced when the standard high power probes are used. This has meant that, although the crystal structure of the final product might be improved, the presence of 'off' flavours has prevented ultrasound being considered as a commercial technique for the crystallisation of edible fats. At Unilever R&D a system has been developed which can investigate the effect of ultrasound on the crystallisation of fats under controlled conditions covering a range of intensities and cooling rates. The intensity levels used were both below and above the cavitational threshold. By keeping the cooling regime constant it has been possible to show that the structure of the final product can vary from a material looking similar to cottage cheese through to a fine cream simply by varying the ultrasonic intensity. This paper describes the effect of ultrasound on both the crystal structure and kinetics of palm oil crystallisation at intensities below and above the cavitational threshold.

Developments in membrane based blood purification therapies often come with longer treatment times and therefore longer blood-material contact, which requires long-term membrane biocompatibility. In this study, we develop for the first time membranes for blood purification using the material SlipSkinÔ, which is a copolymer, made from N-vinylpyrrolidone (NVP) and butylmethacrylate (BMA). Specific attention is focused on understanding the mechanism of pore formation and the tailoring of the membrane mechanical and transport properties to obtain the optimal membrane for blood purification therapies. Polymer composition, solvent type and solvent evaporation time influence membrane morphology and membranes with sieving properties of cascade filters in plasma fractionation applications are developed. The new membranes have very good blood compatibility properties; in fact compared to benchmark flat membranes currently used in the clinic, they have lower platelet adhesion while all other properties (contact activation, thrombogenicity, leukocyte adhesion, hemolysis and complement activation) are also very good and comparable to the benchmarks.

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Abstract. The magnetic dipoldipole interaction between magnetized colloidal particles can lead to particle aggregation (flocculation), when it is strong enough to outweigh the stabilizing forces of electro-chemical origin. An understanding of the timescale at which the magnetic flocculation process is developing is of essential importance for its practical use as a separation technique. Incorporation of the magnetic dipoledpole interaction between the particles into the well established Fuchs theory of flocculation kinetics is difficult, due to the fact that this magnetic interaction is not spherically symmetric. In this paper a numerical approach is presented, in which the basic equation for flocculation is solved allowing for a cylindrically symmetric interaction, such as due to the presence of induced magnetic moments in paramagnetic particles. Experimental observations on the flocculation kinetics of fine-particle (about 0.2 pm diameter) electrostatically stabilized Mnp03 colloids corroborate the predictions of our model calculations.