Impact of flood water on the technical condition of natural gas transmission pipeline valves

Maintaining the reliability of a transmission system's operation is an extremely important issue in the context of ensuring the continuity of gas delivery to customers. Threats to maintaining the reliability of a transmission system's operation may appear at any stage of transmission, and the most common reasons for this are corrosion, material defects or accidental damage. The paper presents the impact of flood water on transmission valves in the context of possible threats to ensuring the technical safety of gas supplies. Hazards are described which relate to the chemical composition of flood water, which may cause corrosion of valve elements and risk of loss of gas pipeline stability caused by flooding. In the context of the design of a natural gas transmission network, the strength aspects and the phenomenon of corrosion are described. The results of tests related to a specific example are presented. The finite element method (FEM) is used to build ball valve models. Two types of valves are modelled for nominal pipeline diameters of 50 mm (DN50) and 200 mm (DN200). The results of the presented analysis show that the leak tightness of the tested valve flange connections was mainly influenced by changes in their operating conditions because the occurring additional forces and moments caused significant changes in the load balance of the flange connections.     

生活污水中蛋白质测试方法研究

分别用Folin-酚改进法、考马斯亮兰法和紫外分光光度法等3种测试方法测试了上海市某小区生活污水中的蛋白质含量,对这3种测试方法进行了比较,并采用氨基酸仪分析了生活污水中蛋白质水解后的氨基酸化学组成.试验结果表明,Folin-酚改进法测试蛋白质浓度的准确性与精确性优于考马斯亮兰法和紫外分光光度法,可用于测定生活污水中蛋白质的浓度;氨基酸仪法测得该生活污水中含有17种氨基酸,其中最多的为谷氨酸(3.6 mg/L),含量最低的是脯氨酸(0.8 mg/L);所测生活污水中蛋白质COD占总COD的18.9%.     

First and second line mechanisms of cadmium detoxification in the lichen photobiont Trebouxia impressa (Chlorophyta)

“First line” defence mechanisms, such as phytochelatin biosynthesis, and “second line” mechanisms, such as stress protein induction, were investigated in cadmium-exposed cells of Trebouxia impressa Ahmadjian, a green microalgal species that is a common photobiont of the lichen Physcia adscendens (Fr.) H. Olivier. When T. impressa cells were exposed to 0, 9 and 18 μM Cd for 6, 18 and 48 h, glutathione and phytochelatins efficiently protected the cells against Cd damage. By contrast, the highest Cd concentration (36 μM) at the longest exposure-time (48 h) caused marked drops in glutathione and phytochelatin content, several types of ultrastructural damage, and decreases in cell density and total chlorophyll concentration. In this case, induction of stress proteins was observed, but only long after the induction of phytochelatins. Thus, stress proteins could represent a “second line” mechanism to counteract Cd stress, activated when there is a decline in the “first line” mechanism of Cd detoxification given by phytochelatins.     

湖北省各主要地市水资源压力指数评价

以湖北省为研究区域,在前人研究基础上,从人口数量压力、水资源数量压力、水环境压力、水资源技术压力、水资源经济压力和水资源紧缺压力6个角度对2009年湖北省各主要地市的水资源压力指数进行了计算和分析。结果表明:湖北省内,武汉市水资源压力最大,鄂州次之,宜昌和黄石市等水资源压力相对较大,黄冈、荆州和十堰市等水资源压力相对较小;武汉市的人口数量压力和水资源紧缺压力大,鄂州市的水资源数量压力大,宜昌和十堰的水环境压力大,随州和黄冈市的水资源技术压力大,孝感市水资源经济压力较大。     

Cluttered habitats reduce wing asymmetry and increase flight performance in European starlings

Fluctuating asymmetry is a measure of developmental instability and results from both genomic and environmental influences. Levels of asymmetry are (in part) influenced by mechanical constraints, as asymmetry is believed to reduce efficiency. Here we have investigated the influence of habitat structure (“open” and “cluttered” environments) on primary flight feather asymmetry and flight performance in European starlings. Our findings indicate that the increased flight demands of cluttered habitats act to reduce primary asymmetry and increase flight performance. These data are discussed in terms of the influence of asymmetry on flight performance and the mechanisms that give rise to asymmetry. This study also presents a novel method, i.e., examining within-individual changes in asymmetry, by which the detrimental and positive influence of the environment could be studied in subsequent field and laboratory studies without confounding environmental effects with genomic influences. Received: 16 June 1997 / Accepted after revision: 28 December 1997     

产朊假丝酵母CANDIDA UTILIS细胞壁对铜离子吸附位点的研究

目前认为所有生物大分子都对重金属离子有较强吸附性 ,但某些分子可特异地吸附重金属 ,并介导酵母细胞对重金属的抗性[1] .其中细胞表面的高分子聚合物倍受关注 ,酵母细胞壁约含 4 0种蛋白分子 ,但有关这些蛋白质在对重金属离子吸附中的作用目前还未见报道 .产朊假丝酵母Ｃａｎｄｉｄａｕｔｉｌｉｓ是重要单细胞蛋白生产菌株之一 ,因其营养条件要求不高 ,对工业废水有较强耐受和转化能力而广泛用于生产和研究 .我们观察了产朊假丝酵母细胞与分离纯化的细胞壁对铜离子的吸附能力差异 ,并对细胞壁上重金属离子吸附位点进行了研究 .1　材料与方…     

粘虫受中红侧沟茧蜂寄生后的生理变化

粘虫（Ｐｓｅｕｄａｌｅｔｉａ ｓｅｐａｒａｔａ）被中红侧沟茧蜂（Ｍｉｃｒｏｐｌｉｔｉｓ ｍｅｄｉａｔｏｒ）寄生以后生理生化上发生了一系列变化。通过被寄生粘虫的生长（体重）、发育（龄期）、血淋巴总蛋白含量和酚氧化酶活性等生理生化指标动态的研究,试图探讨中红侧沟茧蜂对寄主粘虫的生理调节方式和途径,进一步探讨寄生蜂同寄主相互协调、相互影响的关系。图６参２０     

Effect of a subchronic exposure to Simazine on energetic metabolism of common carp (Cyprinus carpio)

The energetic parameters, such as glycogen, glucose, proteins, lactate and adenosine triphosphate (ATP) content and lactate deshydrogenase (LDH) activity in tissues and blood of carps from simazine (2-chloro-4,6-bis(ethylamino)-s-triazine) contaminated waters were investigated. In order to confirm the field results, a laboratory experiment was designed in which carps were exposed to simazine at the concentration level of 45 μ g. L^{? 1} (10-fold of the amount found in natural waters) for 90 days. Fish from a contaminated reservoir showed low glycogen concentrations in hepatopancreas and muscle, while fish in another contaminated reservoir showed high LDH activity together with an increase in lactate content in muscle. Laboratory findings did not confirm field results, and fish exposed to simazine did not show alterations in the parameters studied. The results suggest that carps were not stressed by the presence of the simazine at the concentration levels found in both studies and the mechanisms of defense covered the energetic demand.     

Effect of in vitro administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on DNA-binding activities of nuclear transcription factors in NIH-3T3 mouse fibroblasts

Abstract

Most modern pesticides are expensive. Application of excessive dosage rates is likely to cause undesirable biological side‐effects and is economically wasteful. Non‐uniform distribution of the spray cloud, or application at the wrong time, may result in failure to control the pest. It is the responsibility of the field operator to acquire sufficient knowledge and skill to ensure proper use of the control agents, to increase efficiency of their usage and to reduce unwanted side‐effects. To achieve this goal, he must take into consideration the various physical factors that govern field performance of pesticides.

A simple relationship exists between the spray volume and emission rate used, and droplet size produced. The use of extremely low spray volumes (i.e., those less than 2.0 litre per ha) for forest insect control in Canada, as opposed to higher volumes used in agriculture, necessitates the release of fine droplets (ranging from 20 to 70 μm in diameter) to obtain adequate coverage of the target area. These droplets take a long time to sediment downwards, evaporate in‐flight, become smaller in size and/or form powdery residues, thus contributing to off‐target drift and impaired droplet adhesion to target surfaces. Physical factors such as rain washing, degradation by sunlight and erosion by wind also influence the longevity of pesticide deposits on foliage which is crucial during the critical period of pest control.

Factors affecting the mode of entry into insects are related to the type of ingredients used in formulation. If a pesticide acts via crawling contact, formulations which would provide surface deposits would be more beneficial than emulsions or oil‐based mixes which tend to undergo penetration into foliar cuticle. Physical factors that affect field performance of a pesticide tank mix are related to phase separation and ‘breakdown of emulsions’ in the application equipment; ‘agglomeration and caking’ of wettable powder dispersions at the bottom of the tank; impaired flow behaviour of highly viscous formulations; and coarse atomization of high‐viscosity tank mixes leading to poor target cover.     

Ecological carryover effects complicate conservation

Ecological carryover effects occur when an individual’s previous history and experiences explain their current performance. It is becoming clear that ecological carryover effects are a common phenomenon across taxa, and have the potential to play an important role in governing individual fitness and population dynamics. Carryover effects may reduce the success of conservation efforts aimed at slowing or reversing biodiversity loss. Failure to consider carryover effects might lead to erroneous conclusions about the effectiveness of conservation measures. We suggest that carryover effects are considered explicitly in threat assessment and conservation planning, in order to understand the long-term consequences of stressors, target efforts more effectively, and ensure that the success or failure of conservation efforts is tracked more accurately. We encourage proactive research focused on the proximate mechanisms underlying carryover effects, so that predictive measures of carryover effects in wild populations can be developed and refined. Finally, we suggest that in some cases, positive carryover effects could be exploited for conservation benefit. We conclude that the failure to consider carryover effects in conservation science and practice may put imperiled populations at further risk.