Preparation of thermosensitive and superabsorbent polymer hydrogels from trialkyl‐4‐vinylbenzyl phosphonium chloride‐N‐isopropylacrylamide‐N,N′‐methylenebisacrylamide copolymers and their properties

Thermosensitive and superabsorbent polymer hydrogels were synthesized by copolymerization of three kinds of tri‐n‐alkyl vinylbenzyl phosphonium chlorides (TRVB) with different lengths of alkyl chains, N‐isopropylacrylamide (NIPAAm), and N,N′‐methylenebisacrylamide (MBAAm). The water‐absorption ability and antibacterial activity of the hydrogels against Staphylococcus aureus (S. aureus) were investigated. The water content of TRVB–NIPAAm–MBAAm copolymers decreased with increasing temperature and increased with increasing phosphonium groups in the copolymers, while it decreased with increasing chain length of the alkyl groups in the phosphonium groups as well as with an increasing degree of crosslinking in the copolymers. The TRVB–NIPAAm–MBAAm copolymers with a higher TRVB content in the copolymers exhibited higher antibacterial activity against S. aureus, but decreased with increasing chain length of alkyl groups in phosphonium groups. The TRVB–NIPAAm–MBAAm copolymers exhibited the highest antibacterial activity at 30°C against S. aureus in deionized water. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 115–124, 2001     

X-ray Photoelectron Spectroscopy Study on the Process of Apatite Formation on a Sodium Silicate Glass in Simulated Body Fluid

The process of apatite formation on the surface of Na₂O–SiO₂ glass in a body environment was investigated, mainly by X-ray photoelectron spectroscopy, as a function of soaking time in a simulated body fluid (SBF). The glass was found to release Na⁺ ions via exchange with H₃O⁺ ions in the SBF to form Si—OH groups on its surface. These Si—OH groups induced apatite formation indirectly, by forming calcium silicate and amorphous calcium phosphate. The formation of the calcium silicate and amorphous calcium phosphate is attributed to electrostatic interactions between the Si—OH groups on the glass surface and the calcium and phosphate ions in the SBF.     

Robust vector control of induction motor without using stator androtor circuit time constants

To solve the problem of performance degradation due to parameter variations in an indirect vector control of an induction motor, a novel and simple estimation method for the rotor circuit time constant is presented. The proposed method is based on regulating the energy stored in the magnetizing inductance, which can be calculated from the terminal voltages and currents. From theoretical and experimental results, it is verified that the proposed method can overcome the problem of performance degradation due to parameter variations without the necessity of knowing the values of stator resistance and rotor circuit time constant at all     

A novel alkaline air electrode based on a combined use of cobalt hexadecafluoro-phthalocyanine and manganese oxide

Electrocatalytic reduction of O₂ with dual catalysts of cobalt 1, 2, 3, 4, 8, 9, 10, 11, 15, 16, 17, 18, 22, 23, 24, 25-hexadecafluoro-29 H, 31H-phthalocyanine (CoPcF₁₆) and MnOOH was studied in alkaline media with cyclic and rotating ring-disk electrode (RRDE) voltammetry. Cyclic voltammetric results show that CoPcF₁₆ possesses a good catalytic activity for redox-catalyzing an apparent two-electron reduction of O₂ with superoxide (O₂⁻) as an intermediate. The combined use of CoPcF₁₆ with MnOOH which shows a bifunctional catalytic activity toward the sequential disproportionations of the reduction intermediate and product, i.e. O₂⁻ and peroxide (HO₂⁻), eventually enables an apparent four-electron reduction of O₂ to be achieved at a positively-shifted potential in alkaline media. The possibility of utilizing the dual catalysts for the development of practical alkaline air electrodes was further explored by confining the catalysts in active carbon (AC) and carbon black (CB) matrices that are generally used as the substrate for constructing air electrodes. The RRDE voltammetric results suggest that an apparent four-electron reduction of O₂ reduction can be obtained at the as-prepared carbon-based air electrode at a potential close to that at the Pt-based air electrode, and that the as-prepared electrode shows a high tolerance against methanol and glucose crossover.     

The effect of epiphytic lactic acid bacteria with or without different byproduct from defatted rice bran and green tea waste on napiergrass (Pennisetum purpureum Shumach) silage fermentation

A fermented juice from macerated napiergrass containing epiphytic lactic bacteria (FJLB) and napiergrass was prepared, mixed with defatted rice bran (FJLB + DRB) or dried green tea waste (FJLB + DTW) and freeze‐dried. Silage was treated with FJLB + DRB, FJLB + DTW, DRB or DTW in powder form at levels of 2, 10 and 50 g kg^?1 fresh matter (FM). FJLB in liquid form was added at a level of 10 mL kg^?1 FM. All treated silages were well preserved, with lower pH, acetic acid and NH₃‐N content and higher lactic acid content than that of the control. Butyric acid was present only in the control silage and those treated with DRB or DTW. Without powdered FJLB additives, napiergrass silages had higher pH values, butyric acid and NH₃‐N content, but low lactic acid content compared with powdered FJLB silages. Increasing the amount of all powdered additives had effect on lactic acid and NH₃‐N content. It may thus be concluded that the powder form of FJLB was as effective in improving the fermentative quality of napiergrass as the liquid form. Copyright © 2006 Society of Chemical Industry     

Development and evaluation of a loop-mediated isothermal amplification assay for rapid and sensitive detection of Vibrio parahaemolyticus

Loop-mediated isothermal amplification (LAMP) assays targeting the rpoD and toxR genes were developed to detect Vibrio parahaemolyticus. All 78 tested V. parahaemolyticus strains yielded positive results within 40 min, while negative results were obtained for 69 strains of other organisms even at 60 min. For V. parahaemolyticus ATCC 17802 in pure culture, the detection limits of LAMP assays targeting rpoD and toxR were 3.7 and 450 CFU per test, respectively. Due to the higher sensitivity of rpoD-LAMP, it was further evaluated for the ability to detect V. parahaemolyticus in seafood samples. V. parahaemolyticus populations spiked in short-necked clams were enumerated by the most-probable-number (MPN) method combined with the rpoD-LAMP assay and the MPN method with a culture method using agar medium. The MPN-rpoD-LAMP method had better sensitivity and was more rapid than the conventional method. These results indicate that the MPN-LAMP assay targeting the rpoD gene is a specific, sensitive, and rapid method to enumerate V. parahaemolyticus organisms.     

Accelerated aromatic compounds degradation in aquatic environment by use of interaction between Spirodela polyrrhiza and bacteria in its rhizosphere

Accelerated degradation of organic chemicals by aquatic plant-bacterial associations was reported for the first time with elucidation of the role and contribution of aquatic plant and bacteria in its rhizosphere using a fast-growing giant duckweed, Spirodela polyrrhiza. The results clearly showed the accelerated degradation of all the three aromatic compounds (phenol, aniline and 2,4-dichlorophenol [2,4-DCP]) tested by aquatic plant-bacterial associations. In phenol degradation system, phenol-degrading bacteria indigenous to the rhizosphere fraction of S. polyrrhiza mainly contributed, while in aniline degradation system S. polyrrhiza mainly contributed by stimulating aniline-degrading bacteria both in the rhizosphere and balk water fraction. On the other hand in 2,4-DCP degradation system, S. polyrrhiza itself mainly contributed to its removal by uptake and degradation. Thus, the mechanisms for accelerated removal of aromatic compounds were quite different depending on the substrates. S. polyrrhiza showed selective accumulation of phenol-degrading bacteria in its rhizosphere fraction, while aniline- and 2,4-DCP-degrading bacteria were not much accumulated. S. polyrrhiza secreted peroxidase and laccase. However, both of the enzymatic activities increased with the addition of aromatic compounds, degrading ability of S. polyrrhiza itself should be owing to the production of peroxidase rather than laccase because the change of peroxidase activity and concentration of each aromatic compound well concurred. From the results obtained in the present study, it can be concluded that the feasibility of the use of aquatic plant-bacterial associations to accelerate the degradation of organic chemicals especially recalcitrant compounds in aquatic environment was shown.     

Analysis of disulfoton sulfoxide in chingentsuai by pulsed splitless mass spectrometry using programmed temperature vaporization (PTV) inlet

A peak considered to be due to disulfoton sulfoxide as a metabolite of disulfoton was detected in the analysis of the chingentsuai extraction solution of vegetables by GC-FPD. In the analysis by GC/MS for identification, though the retention time and the mass spectrum were the same as those of the standard, the spectrum was different from MS library data. It appeared that decomposition of disulfoton sulfoxide occurred at the inlet. Therefore, we used a programmed temperature vaporization (PTV) inlet in the pulsed splitless mode to achieve a low inlet temperature and high injection pressure. As a result, the expected mass spectrum of disulfoton sulfoxide was obtained. Under this condition, the peak obtained from chingentsuai was identified as disulfoton sulfoxide. Disulfoton sulfoxide was detected from 2 of 25 chingentsuai samples, at concentrations of 0.66 microg/g and 0.14 microg/g.     

Studies on syntheses and permeabilities of special polymer membranes

Summary An active transport of alkali metal ion through cation exchange membranes was studied under various conditions. This active transport was facilitated by using a greater anion species on an acidic side in a diaphragm cell, in which one side of the solution was adjusted to be acidic and the other side alkaline across the membrane. An active transport fraction of alkali metal ion was in order poly(styrenesulfonate)>benzenesulfonate>Cl^– >I^–>Br^– of anion species on the acidic side. A rate, fraction and period of the active transport of metal ion were significantly influenced by an electric potential gradient in the membrane.