Mitsutaka Kawamura

The structure of glutaraldehyde in aqueous solution determined by ultraviolet absorption and light scattering

The structure of glutaraldehyde (GA) in aqueous solutions has been the subject of much debate. Since there were fundamental problems in the experiments in the preceding studies, in this article, the structure of GA was investigated with uv absorption and light scattering to avoid those problems. It was discovered that 70% glutaraldehyde solution contains a large quantity of polymeric species with cyclic hemiacetal structure. On dilution, the polymerized glutaraldehyde slowly converted to monomers. In dilute solution, glutaraldehyde is almost monomeric at pH 3-8, the major portion taking the cyclic hemiacetal structure. The structure of GA in 20% solution is similar to that in more dilute solution. alpha, beta-Unsaturated structure does not exist in aqueous solution regardless of the concentration of glutaraldehyde.

Rise and Fall of Surface Level of Water Solutions under High Magnetic Field

Magnetic field effects on the surface profile have been investigated for water and copper sulfate aqueous solutions that have very small magnetic susceptibility. When a field of 10 T is applied in a horizontal superconducting magnet, the surface of distilled water was lowered by 39 mm at the field center, relative to the level at the zero field region (Moses effect). In contrast, the surface of a nearly saturated copper sulfate aqueous solution was raised by roughly the same height at the center (reversed Moses effect). The profiles were systematically explained based on the dia- and paramagnetic volume susceptibility values of distilled water and copper sulfate aqueous solution, respectively.

Magnetic field effect on interface profile between immiscible nonmagnetic liquids—Enhanced Moses effect

The change in the interface profile between immiscible nonmagnetic liquids was investigated quantitatively in a superconducting magnet with a large horizontal bore. The interface profile changed into concave down or up at the field center accordingly to the balance of magnetic susceptibilities between the lower and upper liquids. A flat interface was also demonstrated when the susceptibilities were balanced. It was found that modification of the interface profile was significantly amplified under an applied field as low as 1 T when the densities of the two liquids were quite close. The morphological change induced by the applied magnetic field can be used to remove a boundary, which initially separates two liquids without the field, and to initiate a mixing process or a chemical reaction between the two liquids.

Self-sustained pH oscillations in a compartmentalized enzyme reactor system.

This work represents our continued effort toward fulfilling the need to discover a model system for experimental investigations of temporal oscillations in an enzyme-membrane system. In this paper, the regions in the parameter space where self-sustained pH oscillations can be induced for a compartmentalized enzyme reactor system, which consists of a well-stirred reactor, a reservoir and a membrane containing no enzyme, were determined via numerical simulation with two proteolytic enzymes: papain (EC 3.4.22.2) and alpha-chymotrypsin (EC 3.4.21.1). The sizes of the regions were qualitatively compared with those associated with enzymic membrane system. As a result, we found that the possibility of experimentally observing self-sustained oscillations in the compartmentalized papain reactor system, as well as in the papain-membrane system, is high. However, self-sustained pH oscillations are less likely in the compartmentalized alpha-chymotrypsin reactor system than in the alpha-chymotrypsin-membrane system.

Effects of Catalyst Concentration and Gas-liquid Mass Transfer on Coal Liquefaction.

To evaluate the effects of catalyst concentration on liquefaction, concentration distributions of the catalyst particles in a slurry reactor were estimated and autoclave experiments were carried out under various gasliquid mass transfer conditions.The estimation showed following results. The concentration distributions of catalyst particles became more uniform with smaller iron particles. And when dp<dpap=min, ap (surface area of catalyst particles in a slurry) increased with decreasing dp (diameter of catalyst particle).The autoclave experiments showed following results. Coal conversions increased with increasing of catalyst concentration under the good mass tranpfer condition. On the other hand, under the poor mass transfer condition, the conversions decrease at high catalyst concentration.The results which used hydrogenated anthracene oil as a solvent showed higher oil yields with lower hydrogen consumption. Yields of methane under the poor mass transfer condition were higher than those of under the good mass transfer condition, it shows that production of methan reflect the mass transfer condition in the reactor.These results suggest that using of smaller iron particle catalyst and better donor solvent under the condition of better gasliquid mass transfer lead to higher coal conversion.

Morphological Characteristics of β-SiC Ultra-fine Particles Synthesized by a Newly Developed Radiofrequency (r. f.) Thermal Plasma System

β-SiC ultra-fine particles were prepared by feeding reactant gases of CH4 and SiH4 into a newly developed R. F. thermal plasma furnace.Amorphous β-SiC particles were deposited on the inner wall of the plasma torch, while crystalline β-SiC particles were found downstream of the tail flame of the torch.By using TEM micrographs, the configurations of the crystalline β-SiC particles were found to be chain-like agglomerates which consisted of fine primary particles approximately 200A-500A in size.The bonding states between the primary particles were presumed to be sintering from the magnified TEM micrographs.Size distributions for agglomerate particles were determined by conventional particle size analyzers, and these results were compared with that obtained from the TEM micrographs.A dynamic shape factor was introduced in order to account for the behavior of the agglomerates in the various media.

Development of Light-Weight Aggregate Production Process from Coal Ash with a Shaft Kiln (Part 2)

One t/d test plant facilities of the shaft kiln for calcination of coal ash pellets is designed and constructed. Experimental studies are carried out with this test plant to examine the relationship between reactor behavior and product properties and to clarify the technical problems of the shaft kiln necessary to attain the stable operation. It is found that the most important factor is smooth movement of the pellets supllied from the top of the kiln. Steady and smooth discharge of the pellets could be achieved by applying a forced discharger like a ram feeder. The maximum temperature level of the moving bed in the shaft kiln is governed by not only operational conditions but green pellet composition such as carbon and moisture content. The position of the maximum temperature is affected by an air flow rate as well as discharge rate. The calcined pellets are tested according to JIS A 5002 (Light-weight concrete for structure) and Anouncement No. 13 of Environmental Agency (Industrial Waste Disposal Regulation) and tested properties satisfy the specification and regulation values. Especially, the compressive concrete strength shows 550kgf/cm2 which is about 40% stronger than that of JIS value. Conceptual design of a 50t/d pilot plant and cost estimation of the developed process are performed based on the studies conducted up to now. In case of a 1000t/d plant, production cost is estimated under 3000yen/m3.