Graft copolymerization of vinyl monomers in wool fibers

Graft copolymerization of vinyl monomers, mainly methyl methacrylate, in reduced, successively alkylated, or KCN-Treated wool fibers was performed in the redox LiBr–persulfate system without homopolymer. The reduction gives a striking effect in promoting the graft copolymerization. Methylation or ethylene recrosslinking of the reduced wool, especially the former, decreases the graft-on remarkably. By the KCN treatment in which the conversion of disulfide to lanthionine bonds occurs, the grafting is decreased in the bromide–persulfate system but promoted in the system with persulfate alone. Methylation or KCN treatment of wool as well as reduction brings about a great increase in the absorption of persulfate. The grafting of the lanthionine-containing wool in the redox system accompanied by the liberation of bromine might be retarded by the pronounced bromination of monomers over the inhibiting of homopolymerization, because the lanthionine bonds are more stable to bromine than the disulfide bonds. In general, disulfide bonds and the other easily oxidized components of wool may perhaps play an important role in regulating the bromination of monomers and in the graft copolymerization without homopolymer. The molecular weight of graft polymer is decreased distinctly with increasing extent of reduction of wool. From these results, the thiol groups on wool are considered to give predominantly graft centers by the radicalotropy from SO₄, OH·, and/or Br·.     

Formation Mechanism of Hydrous Zirconia Particles Produced by the Hydrolysis of ZrOCl2 Solutions: III, Kinetics Study for the Nucleation and Crystal-Growth Processes of Primary Particles

The formation rate and primary particle size of monoclinic, hydrous zirconia particles produced by the hydrolysis of various ZrOCl₂ solutions (with and without the addition of HCl, NH₄OH, NaCl, CaCl₂, or AlCl₃) were measured to clarify the effects of the H⁺ and Cl⁻ ion concentrations on the nucleation and crystal-growth processes of primary particles of hydrous zirconia. Chemical-kinetic analyses, to which Avrami–Erofeev's equation was applied, and XRD measurements revealed that both the rate constant and the primary particle size of the hydrous zirconia decreased as the concentrations of H⁺ and/or Cl⁻ ions produced by hydrolysis increased. The nucleation rate per unit of ZrOCl₂ concentration and the crystal-growth rate of the primary particles of the hydrous zirconia were determined by analyzing the relationships between the rate constant and primary particle size. The nucleation rate per unit of ZrOCl₂ concentration revealed almost no change and remained constant as the H⁺ and/or Cl⁻ ion concentrations increased, except in the case of a slight increase for ZrOCl₂ solutions with added HCl. The crystal-growth rate decreased as the H⁺ and/or Cl⁻ ion concentration increased. The present kinetic analyses revealed that the decrease in rate constant with increasing H⁺ and/or Cl⁻ ion concentrations resulted from the decrease in the crystal-growth rate. The decreasing tendency of the crystal-growth rate was attributed to interference with crystal growth by the Cl⁻ ions attracted onto the particle surface through the formation of an electric double layer. The formation mechanisms for the primary particles of hydrous zirconia were determined based on the present experimental results.     

Characteristic fungi observed in the fermentation process for Puer tea

The fermentation process for Puer tea, a unique Chinese tea produced by microbial activities, was investigated by physicochemical and microbial analyses. The temperature of a windrow-shaped pile of tea leaves increased instantly at the beginning of fermentation and stayed at around 50 degrees C until day 35, then decreased gradually to room temperature at the end of fermentation, at day 50. Water content was approximately 30% or less, and pH value was maintained at a weakly acidic level of 5 to 6 throughout the fermentation, conditions that are favorable for propagation of fungi including yeasts. Polyphenol, the characteristic component of tea leaves, decreased continually from day 10 to day 50 of fermentation, corresponding well with the fact that the total concentration of fungi steadily increased during the same period. PCR followed by denaturing gradient gel electrophoresis (DGGE) analysis revealed that there were at least two major fungi: Aspergillus niger, which has been well known among Puer tea manufacturers, and Blastobotrys adeninivorans, which is newly recognized in the present study. Furthermore, both of these fungi were observed in the DGGE fingerprint when other commercial Puer tea products were analyzed. These results prompted us to deduce that both A. niger and B. adeninivorans play important roles in the nutritional enhancement of tea leaves during Puer tea fermentation.     

Colorization in YCbCr color space and its application to JPEG images

This paper presents a colorization method in YCbCr color space, which is based on the maximum a posteriori estimation of a color image given a monochrome image as is our previous method in RGB color space. The presented method in YCbCr space is much simpler than that in RGB space and requires much less computation time, while both methods in YCbCr and RGB space produce color images with comparable PSNR values. The proposed colorization in YCbCr is applied to JPEG compressed color images aiming at better recovery of downsampled chrominance planes. Experimental results show that colorization in YCbCr is usually effective for quality improvement of JPEG color images.     

Standardization of New Sliver Probe for Cooling Power Test of Polymer Quenchant

Technical committee for Japanese industrial standard of heat treating oils has studied on the new method for testing cooling power of aqueous quenchants. This method employed the cooling curve test of a new sliver rod probe,which has a metal-sheathed thermocouple at its geometrical center. The experimental study has clarified that this probe has the higher sensitivity and excellent durability. In order to standardize this probe for cooling power test of aqueous quenchants, the repeatability and reproducibility of test results etc. have been studied. D.O.P. (Di-2-ethylthexyl Phthalate)was used as reference quenching fluid for initial calibration and for periodic calibration verification of the probe and system.In addition, 10% brine was used to check the response capability of the probe and system to the sudden change of temperature. These procedures are established according to the experimental investigation. This new test method is going to be built in the revised version of JIS K 2242 “Heat treating oils” as the cooling power test method for aqueous quenchants.     

Formation of dimethylnitrosamine in polluted environment and the role of photosynthetic bacteria

It has been demonstrated that in the decomposition of sludge the carcinogen dimethylnitrosamine was formed.Photosynthetic bacteria were found to be capable of metabolizing this compound.     

Increase of inductance ratio of flat type fault current limiter with high‐Tc superconducting disk

Fault current limiters (FCLs) are expected to reduce fault current and improve stability of power systems. A flat type fault current limiter consisting of the pancake primary winding and a high‐T_c superconducting (HTS) disk was proposed as a modified version of a conventional magnetic shield type of the FCL with the superconducting cylinder. The flat type FCL has the advantage of being manufactured smaller than the cylinder type FCL. It is pointed out, from a magnetic field analysis, that the volume of the flat type FCL is smaller than that of the cylinder type FCL with same magnitude of the limiting inductance. Further, the magnetic field analysis suggests that a high inductance ratio can be realized by radially enlarging both the primary winding and the HTS disk, stacking the FCL modules in layers and sandwiching the primary winding with superconducting disks. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.