A model was proposed for simulation of a particle formation stage in the dispersion polymerization of styrene in ethanol. The role of poly(N-vinylpyrrolidone) molecules grafted by a polystyrene oligomer (PVP-g-PS) was taken into consideration for the particle stabilization. The model was derived based on the following mechanism: (i) polystyrene molecules whose degree of polymerization is greater than j cr precipitate and form particles, (ii) particle aggregation due to the Brownian diffusion and the shear stress of the fluid continues until the amount of the PVP-g-PS molecules is enough to cover all the particle surface, and (iii) particles do not aggregate with each other once the entrire particle surface is covered with the PVP-g-PS molecules. The theoretical particle concentrations calculated using the present model under various monomer concentrations and stirring speeds were in good agreement with the experimental data.

A model is proposed for simulating the particle growth in the dispersion polymerization of styrene in ethanol. The model is based on the following assumptions: (i) the termination reaction in an ethanol‐phase and the chain‐transfer reactions in the ethanol‐phase and particles can be neglected, (ii) the mean volume of the radicals captured by particles is approximately equivalent to that of monomeric radicals, and (iii) the termination rate constant in particles is βgel times that of the ethanol‐phase. The experimental results of the conversion, the particle diameter and the particle number measured at the reaction time of 2 h were used to determine the initial conditions. When the termination rate constant in particles was taken to be about 1/130 of that of the ethanol phase, the calculation results of the conversion and the particle diameter were in good agreement with the experimental data.

Organic solvent-tolerant Pseudomonas aeruginosa LST-03 secretes an organic solvent-stable lipase, LST-03 lipase. The gene of the LST-03 lipase (Lip9) and the gene of the lipase-specific foldase (Lif9) were cloned and expressed in Escherichia coli. In the cloned 2.6 kbps DNA fragment, two open reading frames, Lip9 consisting of 933 nucleotides which encoded 311 amino acids and Lif9 consisting of 1,020 nucleotides which encoded 340 amino acids, were found. The overexpression of the lipase gene (lip9) was achieved when T7 promoter was used and the signal peptide of the lipase was deleted. The expressed amount of the lipase was greatly increased and overexpressed lipase formed inclusion body in E. coli cell. The collected inclusion body of the lipase from the cell was easily solubilized by urea and activated by using lipase-specific foldase of which 52 or 58 amino acids of N-terminal were deleted. Especially, the N-terminal methionine of the lipase of which the signal peptide was deleted was released in E. coli and the amino acid sequence was in agreement with that of the originally-produced lipase by P. aeruginosa LST-03. Furthermore, the overexpressed and solubilized lipase of which the signal peptide was deleted was more effectively activated by lipase-specific foldase.

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