Purification and characterization of rice alpha-glucosidase, a key enzyme for alcohol fermentation of rice polish

Alpha-glucosidase, a key enzyme for nuka-sake brewing, was purified from Oryza sativa cv. Yamadanishiki, which is widely used for sake brewing. The molecular weight of the purified enzyme was 95 kDa. The optimum pH and temperature were 4.5 and 55 degrees C, respectively. The substrate specificity differed from that of Oryza sativa cv. Shinsetsu, which is a variety of rice consumed as a cereal. The extraction of alpha-glucosidase from the rice was stimulated by lactic acid, which suggests that lactic acid plays an important role not only in preventing bacterial contamination, but also in stimulating the parallel fermentation that occurs in nuka-sake brewing.     

Exact Analysis of a One-Dimensional Attractive δ-Function Fermi Gas with Arbitrary Spin Polarization

We study a one-dimensional integrable system of N spin-1/2 fermions with attractive δ-function interaction at zero temperature. The Gaudin integral equation describing the ground state with arbitrary spin polarization is solved in the form of power series. We also study the ground state energy as a function of the coupling constant and the polarization.     

Effects of Solvents in the Polyethylene Glycol Series on the Bonding of Copper Joints Using Ag2O Paste

The effects of reducing solvents on the bonding process using silver oxide paste in a copper joint were investigated. Three solvent types were tested: diethylene glycol (DEG), triethylene glycol (TEG), and polyethylene glycol (PEG). The strength of the joints was assessed by fracturing, which occurred at the interface of the copper oxide layer and the copper substrate in DEG and TEG samples and at the bonded interface in the PEG sample. Analysis of the samples revealed that, in the DEG and TEG samples, the copper substrate was oxidized during the bonding process, which compromised the shear strength of the joints. In contrast, the PEG sample exhibited nonuniform sintering of the silver layer while retaining good shear strength. It was found that the combination of DEG and PEG produced optimum shear strength in the copper joint, as PEG suppressed the growth of copper oxide and DEG promoted the formation of a dense sintered silver layer. The bonding strength achieved was higher than that of the gold-to-gold joint made using standard Pb-5Sn solder.     

正反转双转轮水轮机水力性能研究

研究用于低水头的反转双转轮、双转子小型水力发电设备,探讨反转双转轮的基本原理与水轮机转轮的水力特性,确认了在流量一定的运转工况时反转前转轮转速与正转后转轮转速相等条件下可以得到最高效率、且出力为两转轮之和(单转轮的2倍)。通过模型实验,确认了正反转两转轮的水力性能基本满足一般的相似准则,可以进行实际转轮设计时的换算。     

Gradient orientation pattern matching with the Hamming distance

This paper presents a novel pattern matching technique that is robust to illumination changes and the occlusion problem. The technique is based on the matching of gradient orientations in place of traditional image features such as intensities or gradients. Gradient orientations depend on the texture in an image. They are known to be insensitive to changes of image intensities that are often caused by time-varying illuminations or the auto-gain control (AGC) function of the camera. Moreover,the proposed method employs a voting strategy in the process of matching gradient orientations. The method works remarkably well even when a large part of the pattern is occluded with a foreign object. Consequently, the proposed method is robust to both irregular lighting conditions and the occlusion problem.     

A new control methodology of wind turbine generators for frequency control of power system in isolated island

A wind turbine generator (WTG) system's output is not constant and fluctuates depending on wind conditions. Fluctuating power causes frequency deviations and adverse effects to an isolated power system when large output power from WTG systems is penetrated in the power system. This paper presents an output power control methodology of a WTG for frequency control using a load power estimator. The load power is estimated by a disturbance observer, and the output power command of the WTG is determined according to the estimated load. Besides, the WTG can also be controlled during wind turbulence since the output power command is determined by considering wind conditions. The reduction of the power system frequency deviation by using the WTG can be achieved by the proposed method. The effectiveness of the proposed method is validated by numerical simulations. Copyright © 2010 John Wiley & Sons, Ltd.     

Measurement of the isotopic abundance of boron-10 by inductively coupled plasma-quadrupole mass spectrometry

This article describes the method for measuring the isotopic abundance of ¹⁰B in nuclear grade boron carbide using inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The results of investigation revealed that both the integration time and the dwell time have a major influence on the reproducibility of ICP-QMS measurements. As a result of optimization of the measurement conditions, reproducibility below 0.2% relative standard deviation (RSD) (0.17% RSD maximum) was achieved. In addition, the measured value of the isotopic abundance of ¹⁰B for each sample well agreed with the values measured by the TIMS. Thus, the method described in the present investigation was very effective in the analysis of isotopic abundance of ¹⁰B in B₄C or H₃BO₃. The results of this study suggest that ICP-QMS could be applied to the precise analysis of the isotopic abundance of ¹⁰B required in the field of nuclear applications.     

Simultaneous Measurements of an Ultrasound and a Torsional Oscillator for 4He in a Nanoporous Glass

Previously, we carried out ultrasonic measurements for liquid ⁴He filled in a nanoporous glass (Gelsil), and observed an increase in the sound velocity due to decoupling of the superfluid component. At zero pressure, the superfluid transition temperature T _C is suppressed to 1.4 K from the bulk lambda point, 2.17 K. This behavior is the same as torsional oscillator measurements by Yamamoto et al. (Phys. Rev. Lett. 93:075302, 2004). However, the pressure dependence of T _C and the temperature dependence of the superfluid fraction are very different from the torsional oscillator measurements. In order to clarify the origin of the difference, we have developed a new technique of simultaneous measurement of an ultrasound and a torsional oscillator, and the system successfully works for a nanoporous glass. Here, we compare decoupling of the superfluid component for ⁴He films between an ultrasound and a torsional oscillator.