The MHD effect and its relaxation process on electric current in the electrolysis of ferricyanide reduction and ferrocyanide oxidation

The electrolytic reduction of ferricyanide and the electrolytic oxidation of ferrocyanide have been carried out with exposing the magnetic field of 1000 or 1800 gauss. The current clearly increased after the magnetic exposure. The maximum current was obtained when the magnetic flux directed in parallel with the surface of electrode. These are speculated in terms of magnetohydrodynamic mechanism. The current decrease caused by relaxation process was observed after the removal of magnetic flux. The relaxation time obtained was temperature-dependent. Therefore the values of apparent transition energy, E_trans, were determined from the Arrhenius' plots of relaxation time against temperature. The magnitude of E_trans was dependent on the concentration of ferricyanide or ferrocyanide, and the viscosity and the conductivity of electrolyte solution. The activation energy of viscosity of electrolyte solution was compared with E_trans. As a conclusion, it was suggested that E_trans may be influenced by the velocity of magnetohydrodynamic flow, which was controlled by the diffusion current in electrolysis and the viscosity of electrolyte solution.     

Production and properties of phytase and acid phosphatase from a sake koji mold, Aspergillus oryzae

We identified three types of acid phosphatase (ACP-I, ACP-II, and ACP-III) produced by Aspergillus oryzae in a submerged culture using only phytic acid as the phosphorous substrate. The optimum pH for the activities of the three enzymes was in the range of 4.5 to 5.5. Analysis of the substrate specificities of these enzymes revealed that ACP-I and ACP-III were acid phosphatases, and ACP-II was a phytase. These enzymes were produced during different periods of mycelial growth: ACP-II was produced during the early phase of cultivation (around 24 h), and ACP-I was produced between 24 to 72 h. ACP-III was detected after the production of ACP-I and ACP-II had ceased. The release of phosphate from phytic acid was expected to be due to the cooperative hydrolysis of these enzymes.     

Synthesis and properties of polymeric latex particles and their conjugates with human immunoglobulin G

Polymeric latex particles of uniform size in the range of 750 to 10 000 Å in diameter were prepared by emulsion copolymerization of methyl methacrylate, methacrylic acid, 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate, using sodium dodecylbenzene sulphonate as an emulsifier and ammonium persulphate as an initiator. With a fixed composition of monomers the carboxyl groups on the latex particles ranged from 5 × 10³ to 180 × 10³ per particle, but the average number per unit surface area remained within a limited variation. Human immunoglobulin G (IgG) was covalently bonded to the latex particles by either the carbodiimide or the cyanogen bromide method, taking advantage of carboxyl and hydroxyl groups, respectively. The resulting conjugates exhibited a specific agglutination with rabbit anti-human IgG and sera from rheumatoid arthritis (RA) patients. The immunolatex particles were found to be superior to those derived from nylon-6, which had been used in our previous work, and are expected to offer useful means in various immunological studies.     

Decarboxylation of the 6-nitrobenzisoxazole-3-carboxylate anion catalyzed by cross-linked poly(4-vinylpyridinium) salts

Summary Catalysis of cationic polyelectrolytes for the decarboxylation of 6-nitrobenzisoxazole-3-carboxylate anion was studied in a buffer solution (pH=9.0). Cross-linked poly (4-vinylpyridinium) salts prepared from 4-vinylpyridine and , -dibromides were used as cationic catalysts. The cross-linked catalysts were found to accelerate markedly the decarboxylation in comparison with the linear water-soluble analogues. Effect of the polymer structure such as the length of (CH₂)_x linkages between positive charges on the catalytic activity was examined. It was suggested that the acceleration by the cross-linked polymer catalysts would be due to the hydrophobic microenvironment around the catalytic sites.     

Three-dimensional display of X-ray CT image

Multi-slice images obtained by X-ray CT essentially have a three-dimensional data structure. They are useful for diagnosis and treatment through three-dimensional display. Surface display of organs is an effective three-dimensional display. However, although completely automatic processing of contour extraction is desirable it is also very difficult. For surface display, it is very important to extract contours of organs. Accordingly, using an interactive method, we have developed an algorithm for accurate three-dimensional display after extracting images of the cerebral ventricle. Satisfactory results have been obtained.     

Preparation and characterization by thermal analysis of magnetic latex particles

Emulsion polymerization of styrene and methyl methacrylate in the presence of a ferrofluid was briefly studied. Thermal properties of the resulted latex particles were investigated by TG–DTA analysis. Determination of the residue weight after the thermal analysis that indicated complete decomposition of the organic components was found to be a facile and practical method to determine the magnetite content in the latex particles. The method was applied to magnetic polystyrene latex particles prepared in the presence of various amounts of the ferrofluid. Analysis of the results suggested that the magnetic content in the latex particles is primarily determined by the weight ratio of the ferrofluid to monomer. © 1993 John Wiley & Sons, Inc.     

Effect of Chemical Composition on the Sinterability of Ultrafine Sic Powders

Ultrafine β-SiC powders with an average particle size of 0.01 to 0.06 μm were produced by CVD methods. When these powders contained enough carbon to remove impurity oxygen, sintered bodies with a relative density >95% were uchieved at 2050°C in the presence of 1 wt% boron. The Vickers microhardness reached 21 to 25 GPa at a density of ∼95% .     

Reversible change in the optical rotatory power of poly(L-glutamate) thin film induced by photochromism of a spiropyran

Summary When the thin film of poly(L-glutamate) containing 6-nitroindolinospiropyran was exposed to uv light(mainly 365nm), measurable change in the optical rotatory power was observed, accompanied with the coloration due to the formation of the photo-merocyanine. The change was reversible upon exposure to visible light(>480nm). The extent of the reversible change of the optical rotatory power was found to depend on the concentration of the spiropyran as well as casting concentration. Discussion was made on the mechanism of the appearance of the optical rotatory power.     

Development of high-Jc NbTi multifilamentary superconducting wire with Nb artificial pins for AC applications

High critical current densities of 1.61 × 10¹⁰ A/m² at 1 T, 6.1 × 10⁹ A/m² at 3 T and 2.9 × 10⁹ A/m² at 5 T were achieved by controlling the distribution of Nb artificial pins in NbTi multifilamentary superconducting wires for ac applications. The critical current densities attained are over two times higher than those of conventional ac superconducting wires. This increase can be attributed to the shift of the peak of pinning force density to higher magnetic field by optimizing the pinning parameters. The benefits of increasing critical current densities for ac applications are demonstrated. A 2.5 T/100 kVA ac superconducting magnet was designed and made by using high J_c wire with controlled distribution of Nb artificial pins. Compared with conventional ac superconducting magnets, the new magnet exhibits a drastic decrease in size as well as in ac losses.