Experimental investigations of a loop antenna as electron plasma wave radiator and detector

The radiation and reception characteristics of a circular loop antenna for an electron plasma wave are investigated experimentally. As a result, it is shown that the measured directional radiation and reception patterns agree well with the theoretically predicted ones, and that the quantitatively measured amplitude of the radiated wave potentials are also found to agree fairly well with the theoretically predicted values.     

Site-directed mutagenesis of pseudoazurin from Alcatigenes faecalis S-6; Pro80Ala mutant exhibits marked increase in reduction potential

Pseudoazurin (a blue copper protein or cupredoxin) of a denitrifyingbacterium Alcaligenes faecalis S-6 is a direct electron carrierfor a Cu-containing nitrite reductase (NIR) of the same organism.Site-directed mutagenesis of the pseudoazurin was carried outusing an Escherichia coli expression system. Replacement ofTyr74 by Phe to remove an internal hydrogen bond in the ß-barrelcaused a slight decrease in heat stability as well as a requirementfor a higher concentration of Cu²⁺ for production in the E.colihost. Exchange of Ala for Pro80 adjacent to His81, one of thefour ligands binding a type I Cu atom, caused a marked increasein reduction potential by 139 mV without change in the opticalabsorption spectrum. The ability of the pseudoazurin to transferelectrons to NIR was markedly diminished but the apparent K_mof NIR for pseudoazurin was not affected by the mutation. X-raydiffraction data collected on the oxidized and reduced formsof the Pro80Ala mutant show that a water molecule occupies thepocket created by the absent side chain. This observation suggeststhat the increase in reduction potential may be caused due tothe increased solvent accessibility to the Cu atom. The electrondensity difference maps on these structures (at 2.0 Å)show that this water moves during the change in oxidation state,and that there are small, but localized, conformational changes>6.5 Å from the copper site, as well as movement ofboth the Cu²⁺ and the cysteinate sulfur.     

The Activities of FexO in {CaO‐SiO2‐Al2O3‐MgO‐FexO} Slags at 1723 K

In Japanese steelworks, hot metal is now produced by scrap melting process. With this process removal of sulphur is very much handicapped because of very high sulphur levels (0.04 to 0.09 pct by weight) and relatively low tapping temperatures (1623 to 1723 K). In order to overcome such disadvantages, the authors explored on the phase diagrams of {CaO‐SiO₂‐Al₂O₃‐MgO} slags, and this research revealed that those slags at 35 wt%‐Al₂O₃ would be good candidates as reagents for the removal of sulphur from high sulphur hot metal at relatively low temperatures. For better understanding of the thermodynamic properties of the candidate slags, in this study, activities of Fe_xO were determined by using solid‐state electrochemical cells incorporating MgO‐stabilized zirconia and Mo + MoO₂ reference electrode.     

Study on decomposition process of NaAlH4 by in-situ TEM

In-situ transmission electron microscopy (TEM) has been performed to observe decomposition process of sodium alanate (NaAlH₄) in this work. NaAlH₄ was ground in a glove box under inert gas, and then it was transferred into microscope without exposed to air by Plastic Bag Method. The results of in-situ electron beam diffraction showed that NaAlH₄ decomposed to Na₃AlH₆ + Al, and NaH + Al during heated up to 150 and 200 °C, respectively. Moreover, we obtained the result of high-resolution (HR) TEM images about the decomposition of NaAlH₄ by high voltage electron microscopy (HVEM) of 1250 keV. It showed that the porous structures appeared with increase of temperature. This should be from structural defects and/or cavities due to volume change of the phases. It was also shown that Na₃AlH₆ and Al particles with the grain size of several 10 nm were irregularly distributed near the pores.     

同位素效应对铁中辐照损伤的影响

有关氦与辐照缺陷的相互作用已有不少系统性的工作,但对氢与辐照缺陷的相互作用的研究不多。特别是氢的同位素氘或者氚存在于核聚变反应堆中,关于氢的同位素效应对辐照损伤的研究工作很少。采用离子加速器在室温下对纯铁注入氘离子,经500℃时效1h后,研究了电子辐照下位错环的演变过程并讨论了同位素效应对位错环偏压的影响。实验表明,随辐照剂量的增加,空位型位错环的尺寸逐渐减小直至消失。由于注氘纯铁中的位错偏压小,其空位型位错环缩小的速率比注氢纯铁中空位型位错环小,由此可以推断注氘纯铁比注氢纯铁抗辐照损伤性能好。     

Carryover characteristic during reflood process in large scale separate effects tests

A study on carryover characteristic in the core and upper plenum during the reflood phase in PWR-LOCA was performed with the use of data from the slab core test facility (SCTF) having eight rod bundles scale. Void fraction distribution in the core was strongly related to quench propagation in rod bundles. A correlation for mass effluent rate out of core was derived from the void fraction distribution characteristic. The correlation was found to be widely applicable. On the other hand, the capture of entrained liquid in the upper plenum by structures and water pool is below 30% of the entrainment mass flow rate during most of the reflood phase and increase when the steam velocity decreases. Since entrainment rate into hot leg increases with increase of liquid flow out of the core, the reflood velocity should tend to be suppressed with time because of stronger steam binding effect.     

Direct‐power‐control‐based matrix converter and its operation characteristics

This paper proposes a novel control strategy for a matrix converter, which features direct instantaneous active‐ and reactive‐power control of the converter. The theoretical aspects of the proposed control are discussed, and computer simulation results are presented to confirm the basic controllability of the technique. In addition, several operational characteristics were examined through experimental tests, using a 1.5‐kW prototype. The maximum efficiency and the total input power factor of the prototype with a 30‐Hz output frequency were 95.4% and 99.9% at 1.5‐kW load, respectively. The total harmonic distortion at the rated load was 5.9%. These results demonstrate the feasibility and effectiveness of the proposed strategy. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(2): 53–59, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20886     

ANTIOXIDANT AND ANTI-LIPASE COMPOUNDS ISOLATED FROM HEARTWOOD OF YAKUSHIMA NATIVE CEDAR (Cryptomeria japonica)

This article describes the biological activities of heartwood extracts from Yakushima native cedar (Cryptomeria japonica) and identifies their main active compounds. Black heartwood and red heartwood were each divided into two parts from the center (the pith) to outer heartwood (the cambium). The methanol extracts of those parts were screened for antioxidant and anti-lipase activities. The extract from the pith of the red heartwood showed the highest ORAC activity among the samples. Regarding anti-lipase activity, all the extracts showed relatively high activity (the IC₅₀ value were 9.71–37.24?μg mL^?1). In addition, four compounds were isolated and identified from the pith of red heartwood by NMR and MS analyses. Agatharesinol (3) and sequirin C (4) were thought to be the main active compounds responsible for the antioxidant and anti-lipase activities.