Peptide inhibitors for angiotensin I-converting enzyme from enzymatic hydrolysates of porcine skeletal muscle proteins

Inhibitors of angiotensin I-converting enzyme (ACE) have been shown to have antihypertensive effects and have been utilized for pharmaceuticals and physiologically functional foods. In the present study, efforts were directed to find ACE inhibitory activities derived from muscle proteins. Porcine skeletal muscle proteins were hydrolyzed by eight proteases, and the inhibitory activities of the hydrolysates toward ACE were measured. Among the digests of the water-insoluble protein fraction prepared from muscle, thermolysin digest demonstrated the highest activity. Also, among hydrolysates of porcine myosin produced by the same enzymes, thermolysin digest showed the most potent inhibitory activity. Two ACE inhibitory peptides were purified from thermolysin digest of myosin. The sequences of these inhibitory peptides, named myopentapeptides A and B, were Met-Asn-Pro-Pro-Lys and Ile-Thr-Thr-Asn-Pro. These sequences were found in the primary structure of the myosin heavy chain. The concentrations of the peptides showing 50% inhibition values (IC(50)) of ACE were 945.5 and 549.0 μM, respectively. Also, six tripeptides, Met-Asn-Pro, Asn-Pro-Pro, Pro-Pro-Lys, Ile-Thr-Thr, Thr-Thr-Asn, and Thr-Asn-Pro, which have parts of the sequences of the myopentapeptides, demonstrated activity. Their IC(50) values were 66.6, 290.5, >1000, 678.2, 672.7, and 207.4 μM, respectively.     

Damage of yeast cells induced by pulsed light irradiation

DNA damage, such as formation of single strand breaks and pyrimidine dimers was induced in yeast cells after irradiation by pulsed light, which were essentially the same as observed with continuous ultraviolet (UV) light. The UV-induced DNA damage is slightly higher than seen with pulsed light. However, increased concentration of eluted protein and structural change in the irradiated yeast cells were observed only in the case of pulsed light. A difference in the inactivation effect between pulsed light and UV light was found and this suggested cell membrane damage induced by pulsed light irradiation. It is proposed that pulsed light can be used as an effective sterilizing method for the yeast Saccharomyces cerevisiae.     

Growth and characterization of Cu(InA1)Se2 by vacuum evaporation

Quaternary chalcopyrite compounds Cu(In_1−xAl_x)Se₂ were prepared by vacuum evaporation method. It is found that the ratio of In/Al determines the nature of semiconducting properties from n-type in the region of In/Al 1 to p-type in the region of In/Al > 1.     

Prediction of Aging Characteristics in Natural Rubber Bearings Used in Bridges

Rubber bearings used in bridges are exposed to the air and easily attacked by oxygen, even at room temperature, and heat, light, dynamic strain, and liquids. It is usually known that the degradation of polymers often occurs as a nonuniform or heterogeneous process because aged rubber will prevent deterioration from progressing into the inner rubber bearing. Thermal oxidation tests were carried out on natural rubber (NR) blocks at different elevated temperatures using the modulus profiling method. The development of the heterogeneous property profiles in aged rubber bearings is revealed. The NR blocks display the features of a diffusion-limited oxidation and the properties change most significantly at the surface. However, in the interior region beyond the critical depth, NR does not change. The property variations at the block surface and the interior are quantitatively examined, based on which, the relations are clarified among property variation, temperature, aging time, and relative position inside a rubber bearing. An appropriate aging model is established, which is able to predict the aging characteristics in NR bearing.     

A PAM control method for a matrix converter based on a virtual AC/DC/AC conversion method

In this paper, a novel control method for a matrix converter is proposed. The proposed method is a PAM (Pulse Amplitude Modulation) control method based on a virtual AC/DC/AC conversion method. Output voltage amplitude is controlled by controlling a virtual DC link voltage with a virtual rectifier. Output frequency is controlled by a virtual inverter. First, the proposed method is explained. Next, the validity of the proposed method is confirmed through simulation and experiment using a 750‐W prototype matrix converter. Moreover, various characteristics of the proposed method and conventional virtual AC/DC/AC method are compared through experiment. As a result of the experiment, it has been understood that total harmonic distortion of output current and common‐mode voltage can be reduced compared with the case of using a conventional virtual AC/DC/AC conversion method. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(4): 88–96, 2009; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20601     

Influence of Y2O3 distribution on the rate of tetragonal to monoclinic phase transformation of yttria-stabilized zirconia during hydrothermal aging

Tetragonal to monoclinic phase transformation of yttria-stabilized zirconia, namely plasma-sprayed coatings and sintered bodies containing 4–8 mass % Y₂O₃ during hydrothermal aging was investigated with respect to Y₂O₃ distribution using 1 m area from electron probe microanalysis (EPMA) and 20 nm area from transmission electron microscopy (TEM) analysis. Phase transformation at 473 K was prevented only in plasma-sprayed coatings having more than 6.7 mass % Y₂O₃ in 20 nm microscopic area. Furthermore, it was confirmed influence of Y₂O₃ distribution on the rate constants of this phase transformation was observed at 368 K.     

Basic design of 70-MW-class superconducting generators

The application of superconductivity technology to electric power apparatus is very important from the viewpoint of energy saving. Especially, the superconducting generators using superconductors as the field windings have many merits compared with conventional generators. Super-GM has been researching and developing 70-MW-class model machines since FY 1988 for a scheduled period of eight years, aiming at a 200-MW-class superconducting generator. This paper describes the basic specifications and designs of 70-MW-class superconducting generators by Super-GM and also describes the propriety of these basic specifications and designs.     

Analysis of multiple indicator dilution curves for estimation of renal tubular transport parameters

A model is developed to estimate the renal tubular secretory parameters by the multiple indicator dilution (MID) technique. The model allows the calculation of influx (from plasma space to tubular cell), efflux (from tubular cell to plasma space) and sequestration (from tubular cell to luminal side) rate constants. A program using the MID-statistical analysis with least squares fitting (SALS) system for the estimation of these parameters is presented. A trapezoid rule and a non-linear least squares regression were used to carry out definite integrals of cubic spline function and least squares fitting, respectively. The system presented seems to be useful for the precise and rapid estimation of the tubular secretory rate constants.