Development of Reference Shunt for Short‐Time Alternating High Current Tests and Study of Measuring System

Short‐circuit tests for power circuit breakers and others require alternative short‐time current measurement, from a few kA to over several tens kA. However, the reference measurement system as a national standard or a specified secondary standard instrument to directly perform comparative test as a complete calibration test in high current class has not yet been established globally. The Japan Short‐Circuit Testing Committee (hereinafter referred to as “JSTC”) has therefore developed a shunt resistor that can be used as a standard instrument for high current measurement. Reference system using this shunt resistor is also considered by JSTC. The performance of the newly developed shunt resistor has been checked through several methods, such as resistance measurement, high power current test, high frequency current test, temperature rise test, and interference test. The results of the tests proved satisfactory performance. Resistance of the shunt resistor before and after the tests was invariant and stable. This makes the shunt resistor adequate for a reference in practical use. In addition, evaluation of uncertainty of the whole reference system including this shunt resistor satisfactorily fulfills the requirements of IEC 62475 edition 1.0, 2010.     

THE COMPOSITION AND VITAMIN A VALUE OF THE CAROTENOIDS OF PUMPKINS OF DIFFERENT COLORS

The carotenoid pigments of the yellow and orange flesh varieties of the pumpkins Cucurbita moschata and C.maxima were identified and quantified, α-Carotene, β-carotene, ζ-carotene, β-carotene 5,6-epoxide, β-cryptoxanthin, lutein, taraxanthin, zeaxanthin, luteoxanthin and auroxanthin were detected in the pumpkins. The difference was that the yellow variety of C. moschata had no zeaxanthin. The quantitative patterns of the two varieties were similar. Although some quantitative variation was observed, lutein, β-carotene and luteoxanthin predominated. The difference in the color between the two varieties resulted from these quantitative differences in carotenoid composition. The vitamin A activity of the C. moschata variety with yellow flesh was higher than that of the C. maxima, which had many oxygenated carotenoids.     

冲击电压下残余电荷对沿面放电发展的影响

固体绝缘的表面是高压电力设备绝缘的最薄弱环节,很多绝缘事故都是由沿面放电造成的。发生放电后,电荷会在绝缘表面积聚,会很大程度上影响下一次放电的产生与发展。为此,通过观测在极性交替变化的冲击电压作用下沿同轴圆柱形聚对苯二甲酸乙二醇酯(PET)绝缘表面放电的发展以及测量放电后表面残余电荷电位的分布,来研究残余电荷对沿面放电的影响。研究表明,在改变冲击电压的极性后,由于反极性残余电荷的影响,放电会被促进,放电通道会沿着前一次放电的通道向前发展,并且会比前一次放电距离略长,放电的强度会增强,放电的发展速度也会加快。在沿着放电通道方向,表面电荷电位梯度可以明显分为两部分:在放电头部的20mm区域,电位梯度较大,为流注放电;而在后面的主干部,电位梯度平缓,为先导放电。     

添加剂对酸性橙7水溶液光褪色的影响

本文研究了添加剂对酸性染料酸性橙７水溶液光褪色的影响．二氨基蒽醌一般能抑制褪色,这是由于二氨基蒽醌对水中生成的单线态氧产生湮灭作用;环糊精抑制褪色,是由于其包接作用使染料的偶氮基团被保护起来;二氧化钛能显著促进光褪色,是由于它的光催化作用．     

Impact of coronary artery calcification in hemodialysis patients: Risk factors and associations with prognosis

The risk factors of coronary artery calcification (CAC) and the impact of CAC on cardiovascular events, cardiovascular deaths, and all‐cause deaths in hemodialysis (HD) patients have not been fully elucidated. We examined the CAC score (CACS) in 74 HD patients using electron‐beam computed tomography. Fifty‐six patients underwent a second electron‐beam computed tomography after a 15‐month interval to evaluate CAC progression. We evaluated (1) the risk factors for CAC and its progression and (2) the impact of CAC on the prognosis. In the cross‐sectional study, HD vintage and high‐sensitive C‐reactive protein (hsCRP) were the independent risk factors for CAC. In the prospective cohort study, delta CACS (progression of CAC) was significantly correlated with hsCRP, fibrinogen, and serum calcium level in the univariate analysis. Stepwise multiple regression analysis revealed that only hsCRP was the independent risk factor for CAC progression in HD patients. Kaplan‐Meier survival analysis revealed that cardiovascular events (P<0.0001), cardiovascular deaths (P=0.039), and all‐cause deaths (P=0.026) were significantly associated with CACS. In conclusion, CAC had significantly progressed in HD patients during the 15‐month observation period. Microinflammation was the only independent risk factor for CAC progression in HD patients. The advanced CAC was a significant prognostic factor in HD patients, i.e., which was strongly associated with future cardiovascular events, cardiovascular deaths, and all‐cause deaths.     

PARTIAL PURIFICATION AND PROPERTIES OF PUMPKIN LIPOXYGENASE WITH CAROTENE-BLEACHING ACTIVITY

From locally grown pumpkins, an active lipoxygenase preparation with an active carotene-bleaching factor was partially purified by ammonium sulfate fractionation, gel filtration, and ion-exchange chromatography. The enzyme had a pH optimum at 6.5 and was inactive at pH below 3 and above 10. The maximum activity occurred at 30°C. The apparent K_m determined in the presence of linoleate was 0.33 × 10^?3 M. The heavy metals Hg²⁺, Cu²⁺, Co²⁺, and Fe³⁺ were effective inhibitors of this enzyme. Cyanide, fluoride, and L-ascorbic acid also inhibited lipoxygenase activity. Carotene-bleaching activities operated strongly on the lipoxygenase fraction and slightly on the denatured lipoxygenase and hemoproteins treated with heat.     

Conversion of Provitamin D3 to Vitamin D3 by Monochromatic Ultraviolet Rays in Fish Dark Muscle Mince

To determine whether the photochemical conversion of provitamin D₃ is possible in fish meat, the dark muscle of skipjack was irradiated with monochromatic ultraviolet rays (peak, 305 nm; range, 280–360 nm) under various conditions of both time of exposure and strength of light. The vitamin D₃ and provitamin D₃ content were analyzed by HPLC. The vitamin D₃ content increased, and the provitamin D₃ content decreased with 20W light at a distance of 50 cm. The conversion was at a maximum 15 hr after the start of irradiation and about 20% of the provitamin D₃ changed to vitamin D₃