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It has been about 10 years since the titanium electrode plated with platinum appeared in electrochemical industry, and it has been evaluated as an excellent insoluble electrode. It is said that more than dozens of patents on the manufacturing method of this electrode have been published. However, the electrode having very high corrosion resistance has never been manufactured.The activation energy for the interface reaction between titanium and the acid was calculated from the measured rate of dissolution of titanium in hydrofluoric acid, and the mechanism of dissolution of titanium was estimated as an essential factor in plating platinum on titanium in aqueous solution.The following results were obtained.1) The change in activation energy of titanium in hydrofluoric acid with the concentration of acid was as follows:Concentration Activation energy 2% 9.5Kcal.mol-11% 9.7Kcal.mol-10.5% 9.3Kcal.mol-12) The change of energy, when the solution was being stirred, was as follows:Concentration Activation energy2% 9.7Kcal.mol-11% 9.6Kcal.mol-10.5% 9.4Kcal.mol-13) Almost the same values of activation energy were obtained between the solution with and without stirring, even though the reaction rate was not determined owing to the diffusion by stirring. Therefore, it was concluded that the reaction rate is not determined by the diffusion process.

(1) 飼料中の糖質の全部を細麦粉とした普通食, および糖質の一部 (全飼料中の13%) をD-キシロース, 蔗糖に代えた飼料を3群の幼若シロネズミに与え, その成長曲線を比較した。キシロース群は初期の約10日間, 一部に下痢がみられ, 摂食量も他の2群に比べて少なく, 体重増加の遅延がみられ, 以後の成長曲線の勾配は他群と差はなかった。(2) キシロース群の摂食量と同量に制限した蔗糖食を与えた対照減餌群と, キシロース群の成長曲線を比較したが両者の間に差は認められなかった。(3) キシロース食投与後の尿および血清中に, 済紙クロマトグラフィーによって, キシロースが検出された。(4) 組織学的検索を行なったが, 3群の肝, 腎, 心, 脾, 眼など主要臓器に, いずれも著明な異常所見は認められなかった。

Summary Iron-chelating enzyme was extracted from rat-liver mitochondria. The measurement of the stoichiometry showed that no side reaction occurred. The reaction product was heme, not hemeprotein. Some other properties, such as pH response, Km for iron and protoporphyrin and effect of supernatant are reported.

Background The development of blood flow in the heart is crucial for heart function and embryonic survival. Recent studies have revealed the importance of the extracellular matrix and the mechanical stress applied to the valve cushion that controls blood flow to the formation of the cardiac valve during embryogenesis. However, the events that trigger such valve formation and mechanical stress, and their temperature dependence have not been explained completely. Medaka (Oryzias latipes) inhabits a wide range of East Asia and adapts to a wide range of climates. We used medaka embryos from different genomic backgrounds and analyzed heartbeat characteristics including back-and-forth blood flow and bradyarrhythmia in embryos incubated at low temperature. We also used high-speed imaging analysis to examine the heartbeat of these animals after transient exposure to low temperature. Results Embryos of the Hd-rR medaka strain exhibited back-and-forth blood flow in the heart (blood regurgitation) after incubation at 15°C. This regurgitation was induced by exposure to low temperature around the heartbeat initiation period and was related to abnormalities in the maintenance or pattern of contraction of the atrium or the atrioventricular canal. The Odate strain from the northern Japanese group exhibited normal blood flow after incubation at 15°C. High-speed time-lapse analysis of the heartbeat revealed that bradyarrhythmia occurred only in Hd-rR embryos incubated at 15°C. The coefficient of contraction, defined as the quotient of the length of the atrium at systole divided by its length at diastole, was not affected in either strain. The average heart rate after removing the effect of arrhythmia did not differ significantly between the two strains, suggesting that the mechanical stress of individual myocardial contractions and the total mechanical stress could be equivalent, regardless of the presence of arrhythmia or the heart rate. Test-cross experiments suggested that this circulation phenotype was caused by a single major genomic locus. Conclusions These results suggest that cardiogenesis at low temperature requires a constant heartbeat. Abnormal contraction rhythms at the stage of heartbeat initiation may cause regurgitation at later stages. From the evolutionary viewpoint, strains that exhibit normal cardiogenesis during development at low temperature inhabit northern environments.