Effects of acute temperature or salinity stress on the immune response in sea cucumber, Apostichopus japonicus

Invertebrates are increasingly raised in mariculture, where it is important to monitor immune function and to minimize stresses that could suppress immunity. The activities of phagocytosis, superoxide dismutase (SOD), catalase (CAT), myeloperoxiclase (MPO), and lysozyme (LSZ) were measured to evaluate the immune capacities of the sea cucumber, Apostichopus japonicus, to acute temperature changes (from 12 degrees C to 0 degrees C, 8 degrees C, 16 degrees C, 24 degrees C, and 32 degrees C for 72 h) and salinity changes (from 30 parts per thousand to 20 parts per thousand, 25 parts per thousand, and 35 parts per thousand for 72 h) in the laboratory. Phagocytosis was significantly affected by temperature increases in 3 h, and by salinity (25 parts per thousand and 35 parts per thousand) changes in 1 h. SOD activities decreased significantly in 0.5 h to 6 h samples at 24 degrees C. At 32 degrees C, SOD activities decreased significantly in 0.5 h and 1 h exposures, and obviously increased for 12 h exposure. CAT activities decreased significantly at 24 degrees C for 0.5 h exposure, and increased significantly at 32 degrees C in 3 h to 12 h exposures. Activities of MPO increased significantly at 0 degrees C in 0.5 h to 6 In exposures and at 8 degrees C for 1 h. By contrast, activities of MPO decreased significantly in 24 degrees C and 32 degrees C treatments. In elevated-temperature treatments, activities of LSZ increased significantly except at 32 degrees C for 6 h to 12 h exposures. SOD activity was significantly affected by salinity change. CAT activity decreased significantly after only 1 h exposure to salinity of 20 parts per thousand.. Activities of MPO and LSZ showed that A. japonicus tolerates limited salinity stress. High-temperature stress had a much greater effect on the immune capacities of A. japonicus than did low-temperature and salinity stresses. Crown Copyright (C) 2008 Published by Elsevier Inc. All rights reserved.

Necessity of dietary lecithin and eicosapentaenoic acid for growth, survival, stress resistance and lipoprotein formation in gilthead sea bream Sparus aurata

The substitution of dietary docosahexaenoic acid (DHA) with eicosapentaenoic acid (EPA) reduces larval growth in gilthead sea bream. However, the value of EPA when dietary DHA is able to meet the requirements of the larvae has not been sufficiently studied. Dietary phosphoacylgliceride levels also affect fish growth and it has been suggested that they enhance lipid transport in developing larvae. The present experiment was carried out to further study the effect of dietary lecithin and eicosapentaenoic acid on growth, survival, stress resistance,. larval fatty acid composition and lipid transport, when DHA is present in the microdiets of gilthead:sea bream. Eighteen thousand gilt-head sea bream larvae of 4.99+/-0.53 mm total length were fed three microdiets tested by triplicate: a control diet [2% soybean lecithin (SBL) and 2.89% EPA], a low EPA diet,(2% SBL and 1.63% EPA) and a no SBL diet (0% SBL and 2.71% EPA). Handling, temperature and salinity tests determined larval resistance to stress. The results show that when dietary DHA levels are high, but dietary arachidonic acid (ARA) levels are about 0.2%, EPA is necessary to improve larval growth, and survival. Larval EPA content, but not DHA or ARA, was affected by dietary EPA levels. Increased dietary EPA improved larval stress resistance to handling and temperature tests, which could be related to its possible role as a regulator of cortisol production whereas it did not affect stress resistance after salinity shock. Larvae fed the no SBL diet showed a lower lipid content characterized by a low proportion of saturated and monounsaturated fatty acids, together with a significant reduction in the appearance of lipoprotein particles in the lamina propria and in the size of such particles, denoting a critical reduction in dietary lipid transport and utilization, and lower larval growth and survival rates.

Effect of H2S on stress corrosion cracking and hydrogen permeation behaviour of X56 grade steel in atmospheric environment

Susceptibility to stress corrosion cracking of X56 steel and its relationship with hydrogen permeation behaviour in atmospheric environment containing H2S was investigated by hydrogen permeation tests at a slow strain rate. The results show that: the fracture strain decreases with the decrease of strain rate under the same experimental conditions; the fracture strain also decreases with the increase of H2S concentration under the same strain rate, and the increased concentration of H2S has no significant effect on the hydrogen permeation in the first wet, etc. dry cycle, however has lead to increased hydrogen permeation in the later cycles. The SEM images of the fractured surfaces show clear evidences of enhanced stress corrosion cracking susceptibility by H2S.

Stress corrosion cracking of AISI 321 stainless steel in acidic chloride solution

The stress corrosion cracking (SCC) of LambdaISI 321 stainless steel in acidic chloride solution was studied by slow strain rate (SSR) technique and fracture mechanics method. The fractured surface was characterized by cleavage fracture. In order to clarify the SCC mechanism, the effects of inhibitor KI on SCC behaviour were also included in this paper. A study showed that the inhibition effects of KI on SCC were mainly attributed to the anodic reaction of the corrosion process. The results of strain distribution in front of the crack tip of the fatigue pre-cracked plate specimens in air, in the blank solution (acidic chloride solution without inhibitor KI) and in the solution added with KI measured by speckle interferometry (SPI) support the unified mechanism of SCC and corrosion fatigue cracking (CFC).

Sensitisation identification of stainless steel to intergranular stress corrosion cracking by atomic force microscopy

A new technique was developed for characterisation of stainless steel to intergramilar stress corrosion cracking by atomic force microscopy. The technique proved to be effective in sensitisation identification of AISI 304 stainless steel and might be promising in sensitisation identification of other stainless steels. (c) 2007 Elsevier B.V. All rights reserved.

断陷湖盆缓坡带成藏模式研究

Halfgraben-like depressions have multiple layers of subtle traps, multiple coverings of oil-bearing series and multiple types of reservoirs. But these reservoirs have features of strong concealment and are difficult to explore. For this reason, many scholars contribute efforts to study the pool-forming mechanism for this kind of basins, and establish the basis for reservoir exploration and development. However, further study is needed. This paper takes HuiMin depression as an example to study the pool-forming model for the gentle slope belts of fault-depression lake basins. Applying multi-discipline theory, methods and technologies including sedimentary geology, structural geology, log geology, seismic geology, rock mechanics and fluid mechanics, and furthermore applying the dynamo-static data of oil reservoir and computer means in maximum limitation, this paper, qualitatively and quantitatively studies the depositional system, structural framework, structural evolution, structural lithofacies and tectonic stress field, as well as fluid potential field, sealing and opening properties of controlling-oil faults and reservoir prediction, finally presents a pool-forming model, and develops a series of methods and technologies suited to the reservoir prediction of the gentle slope belt. The results obtained in this paper richen the pool-forming theory of a complex oil-gas accumulative area in the gentle slope belt of a continental fault-depression basin. The research work begins with the study of geometric shape of fracture system, then the structural form, activity stages and time-space juxtaposition of faults with different level and different quality are investigated. On the basis of study of the burial history, subsidence history and structural evolution history, this paper synthesizes the studied results of deposition system, analyses the structural lithofacies of the gentle slope belt in the HuiMing Depression and its controlling roles to oil reservoir in the different structural lithofacies belts in time-space, and presents their evolution patterns. The study of structural stress field and fluid potential field indicates that the stress field has a great change from the Dong Ying stages to nowadays. One marked point among them is that the Dong Ying double peak- shaped nose structures usually were the favorable directional area for oil and gas migration, while the QuDi horst became favorable directional area since the GuanTao stage. Based on the active regular of fractures and the information of crude oil saturation pressure, this paper firstly demonstrates that the pool-forming stages of the LingNan field were prior to the stages of the QuDi field, whici provides new eyereach and thinking for hydrocarbon exploration in the gentle slope belt. The BeiQiao-RenFeng buried hill belt is a high value area with the maximum stress values from beginning to end, thus it is a favorable directional area for oil and gas migration. The opening and sealing properties of fractures are studied. The results obtained demonstrate their difference in the hydrocarbon pool formation. The seal abilities relate not only with the quality, direction and scale of normal stress, with the interface between the rocks of two sides of a fault and with the shale smear factor (SSF), but they relate also with the juxtaposition of fault motion stage and hydrocarbon migration. In the HuiMin gentle slope belt, the fault seal has difference both in different stages, and in different location and depth in the same stage. The seal extent also displays much difference. Therefore, the fault seal has time-space difference. On the basis of study of fault seal history, together with the obtained achievement of structural stress field and fluid potential field, it is discovered that for the pool-forming process of oil and gas in the studied area the fault seal of nowadays is better than that of the Ed and Ng stages, it plays an important role to determine the oil column height and hydrocarbon preservation. However, the fault seal of the Ed and Ng stages has an important influence for the distribution state of oil and gas. Because the influential parameters are complicated and undefined, we adopt SSF in the research work. It well reflects synthetic effect of each parameter which influences fault seal. On the basis of the above studies, three systems of hydrocarbon migration and accumulation, as well as a pool-forming model are established for the gentle slope belt of the HuiMin depression, which can be applied for the prediction of regular patterns of oil-gas migration. Under guidance of the pool-forming geological model for the HuiMin slope belt, and taking seismic facies technology, log constraint evolution technology, pattern recognition of multiple parameter reservoir and discrimination technology of oil-bearing ability, this paper develops a set of methods and technologies suited to oil reservoir prediction of the gentle slope belt. Good economic benefit has been obtained.

金川镍矿充填法开采引起地岩体移动和地表变形研究

Cut-and-filling stoping becomes more and more important in mining industry for the advantage in protecting environment and its adaptability. However, there is less research in the movement of rock mass and the ground displacement caused by the mining method. In this paper, based on relevant geological and geotechnical test data, the strata movement and the ground displacement of Jinchuan nickel mine are studied comprehensively. The main achievement in this paper can be drawn as follows. Geologic conditions of mining area No.2 of Jinchuan Nickel mine are summed up and influential factors of the movement of rock mass and the surface displacement are analyzed. For recognized the shape of orebody No.l, three-dimensional model is established with 3D Studio MAX software. Based on reconnaissance trip, the monitoring data of GPS and ground fissures in mining area No.2 of Jinchuan Nickel mine are discussed. Then, the rule of the surface displacement and the reason of ground fissures generation are preliminary analyzed. The characteristic of ground movement, surrounding stress and strain in the process of excavation and backfilled is research and analyzed with the method of numerical simulation. The rule of the movement of rock mass and the surface displacement in mining area No.2 of Jinchuan Nickel mine is summed up. The influence of the movement of rock mass and the surface displacement by the dip angle of orebody No.l in mining area No.2 is examined and then the strata movement and the ground displacement is predicted.