Renal responses of Australian lungfish to vasotocin, angiotensin II, and NaCl infusion

The Australian lungfish (Neoceratodus forsteri) responds to intravenous injections of 0.63 ng/kg or more of arginine vasotocin with increased dorsal aortic blood pressure, inulin clearance, urine flow, and tubular rejection of Na+. Single injections of 1 ng/kg or more of angiotensin II or norepinephrine also increase dorsal aortic pressure but do not cause consistent diuresis and natriuresis, Continuous infusions of angiotensin II or repeated injections of norepinephrine produce sustained hypertension and more modest diuresis and natriuresis than are seen after injections of arginine vasotocin that cause less hypertension. Infusions of isosmolar or hyposmolar NaCl solutions increase blood pressure, inulin clearance, urine flow, and tubular Na+ rejection in a manner resembling the response to argininge vasotocoin injections. These data are consistent with the hypothesis that arginine vasotocin is released in response to volume expansion in lungfishes and that it may act on the kidney as a diuretic and natriuretic hormone. They do not rule out a more direct action of expansion on renal functions.     

Investigation on bonding quality of beech wood (Fagus orientalis L.) veneer during high temperature drying and aging

In the present study, the effects of high drying temperature and UV light induced aging on bonding quality of plywood manufactured from untreated and treated veneer layers were investigated. Rotary cut veneers with dimensions of 500 mm×500 mm×2 mm produced from beech (Fagus orientalis Lipsky) log were selected for topochemical, chemical and mechanical analyses. The veneer sheets were oven-dried at 100°C and 180°C after the peeling process. Afterwards, the surfaces were exposed to artificial UV irradiation in an UV chamber for 24 h, 48 h and 72 h representing natural sun irradiation of 2, 4 and 6 months, respectively. Topochemical distribution of lignin and phenolic extractives of the treated and untreated veneers was investigated on a cellular level using UV microspectrophotometry (UMSP). For the chemical characterization of accessory compounds high performance liquid chromatography (HPLC) was used. Furthermore, the shear and bending strengths of plywood manufactured from the treated samples are determined in order to study the bonding quality. The UV microscopic detection shows that after high drying temperature and aging treatment, lignin condensation occurs. With increasing drying temperature and aging duration, more phenolic extractives are situated in parenchyma cells and vessel lumens which can be proved by increased absorbance at 278 nm. The HPLC analysis of the treated tissue showed distinct signals of polymerized compounds such as catechin and 2,6-dimethoxybenzoquinone which are chromophoric compounds in discolored beech wood. The mechanical properties of plywood showed that with increasing drying temperature up to 180°C does not negatively affect shear and bending strengths of samples. After exposure of the veneers to UV irradiation (especially 6 months), decreasing shear and bending strengths of plywood samples can be observed.     

电厂蒸汽回路系统中腐蚀损伤的决定论预测

局部腐蚀,包括点腐蚀、应力腐蚀开裂和腐蚀疲劳是导致电厂发电装置损伤的重要原因,它们诱发50%以上的意外停机事故。迄今,腐蚀破坏的预测一直沿用经验和统计的方法,但是,由于已证实该方法的适用性和其结果的准确性欠佳,故不宜作为例行检修规程的基础。本文提出了预测局部腐蚀损伤的决定论方法,并使用这个方法说明点腐蚀如何引发低压蒸汽轮机涡轮盘Wilson线下游部位的应力腐蚀开裂(SCC),我们的计算表明SCC的萌发与扩展对蒸汽小氧含量、冷凝液膜的环境和涡轮盘所承受的应力这三个因素敏感。     

STUDY OF K_(2)O·6TiO_(2) WHISKER REINFORCED AI COMPOSITES FOR THEIR MECHANICAL PROPERTIES AND INTERFACIAL STRUCTURES

A newly developed whisker K_2O 6TiO_2 reinforeed 6061Al composite was prepared bysqueeze casting process.The flexural strength of the composite is 518MPa,and deereasesto 490MPa after T6 treatment.The hardness of the composite also shows the similarchange while T6 treating.The results of HRTEMobservation may explaine this property.change.It was considered that there is a continuous TiO layer at the whisker-matrix inter-face,which is easily to react with the segregated Mg and to form MgTi_2O_4,MgAl_2O_4.Thethickening of TiO layer after T6 treatment is the main reason resulting is strength degra-dation of composite.     

Cholera in Portugal, 1974.I. Modes of transmission

In April-November 1974, Portugal had a cholera epidemic caused by Vibrio cholerae El Tor Inaba with 2467 bacteriologically confirmed hospitalized cases and 48 deaths. Most of the country was affected, with 17 of the 18 districts reporting cases. V. cholerae was isolated from 42 per cent of shellfish tested during the epidemic, and an epidemiologic study found that a history of consumption of raw or poorly cooked cockles was significantly more common among cholera patients than among paired controls. Water from a spring and a brand of commercially bottled water were also found to be vehicles of transmission of cholera. Although night soil was sometimes used on gardens, consumption of raw fruits and vegetables was not associated with illness.