MICROSTRUCTURE TRANSFORMATION IN THE WELDING HEAT AFFECTED ZONE OF 800MPa GRADE ULTRA FINE STRUCTURED STEEL

The transformation behavior and microstructure development in the heat affected zone(HAZ)of 800MPa grade ultra fine structured steel was investigated.It was found that the HAZ has intermediate temperature transformation characteristics in a wide range of cooling rates,with the bainite sheaves consisting of bainite ferrite plates without carbide precipitation and retained austenite in the fast cooling regime.At relatively high cooling rates,which corresponded to low heat inputs,the hardness of the simulated HAZ was above that of the base metal.When the cooling rate was below 9C/s,the welding HAZ would have an obvious softening.The analysis of transformation rates in continuous cooling processes was completed by numerical differential method.The result indicated that the microstructure transformation rate of the HAZ in 800MPa grade ultra fine structured steel changed sharply to slow speeds when the cooling time t8/5 is longer than 7s.

Biomarkers and Ultra Structural Evaluation of Marine Pollution by Polycyclic Aromatic Hydrocarbons

The present study is endeavored to study the oxidative stress and antioxidant response as well as the ultrastructural change of both liver and muscle tissues of Siganus rivulatus collected from polluted region (El-Mex Bay) and control region (Marsa Matrouh) to identify the significance of biomarkers. The results revealed that, El-Mex Bay was polluted by different types of chemicals including hydrocarbons comparing with the reference area (Matrouh area). Where, the concentration range of total hydrocarbons in sediment samples collected from Matrouh coast was 409.24 - 521.26 ng/g, dry weight, where as this range in sediment samples collected from El-MexBay was 4159.77 - 4589.81 ng/g, dry weight. In this context, the induction of antioxidant systems in fish collected from polluted area in response to oxidative stress should be considered as a clear indication of the presence of pollution and environmental health degradation. Also, The increase in lipid peroxidation was a useful indicator of the pollution load in the present study. The results suggest that chemical pollution is capable of inducing morphological alteration in liver offish collected from polluted area. The present study indicated that ultra-structural changes serveas biomarker of stress in aquatic environment.

Acclimatory responses to high-salt stress in Chlamydomonas (Chlorophyta, Chlorophyceae) from Antarctica

Antarctic ice microalga can survive and thrive in channels or pores containing high salinity in Antarctic ice layer. In this study, it was found that cell membrane permeability of green microalga Chlaraydomonas sp. L4 from Antarctic sea ice was high in cells treated with hypersalinity due to the induction of active oxygen and radicals. However, increased super oxide dismutase （SOD） scavenged harmful free radicals effectively to keep cell membrane integrity. Also, the analysis of membrane fatty acids demonstrated the content of saturated fatty acids and monounsaturated fatty acids in- creased and polyunsaturated fatty acids decreased under the high-salt treatment for 14 d, which effectively reduced the membrane fluidity and minimized the injury to cell membrane. The morpho- logical changes showed that hypersalinity induced the increase of cell volume and the consumption of starch granules. However, because of the increase in detoxification of vacuoles, electron-dense deposits and SOD activity under high-salt stress, the complete noninterference thylakoids, mito- chondria and cell nucleus maintained cellular fundamental metabolism. Global-expression profiling of proteins showed eight protein spots disappeared, 18 protein spots decreased and 18 protein spots were enhanced after the high-salt shock obviously （P 〈0.05）. One new peptide （pI 6.90; MW 51 kDa） was primarily confirmed as the processor of light reaction center protein CP43 in photosystem II, which increased photosynthesis ability of Chlamydomonas sp. L4 treated with high salinity.

Effects of Selenium on Lipid Peroxidation of Soybean Seedings under Salt Stress

Experiments were conducted to study the effects of selenium (Se) on glutathione peroxidase(GSH-Px) activity and the accumulation of malonaldehyde(MDA),the product of lipid peroxidation in soybean seedling, as well as the effect of Se on cell ultra structure of soybean leaf and nascent root under salt stress. Results showed that appropriate amount of Se addition increased GSH-Px activity in soybean leaves from 0. 810 to 1. 421μmol·g-1 fresh weight·min-1 F = 9.12, and reduced the concentration of MDA from 20.17 to 16.16 μmol·g-1 fresh weight, F = 5.44. Under salt stress,no obvious damage on chloplast membrane was observed in Se treated seedlings,and the structures of chloplast and mitochondrion were integrate,whereas in control (no Se addition),the cell membrane was destroyed seriously,chloplast degraded and mitochondrion disappeared. Compared with control,Se addition increased the dry matter weight of seedling by 2.92% to 21.86%, F =5.97.

Effect of hypertransfusion on the gastrointestinal tract after cardiac arrest in a porcine model

BACKGROUND:This study aimed to determine the potential protective effect of inducing hypertransfusion to the gastrointestinal tract following a porcine model of cardiac arrest and cardiopulmonary resuscitation(CPR) by evaluating the influence of gastrointestinal ultrastructure,ATPase and serum diamine oxidase.METHODS:Ventricular fibrillation was induced by programmed electrical stimulation in 16 male domestic pigs(n=8/group).Four minutes after ventricular fibrillation,CPR was performed.The pigs that successfully restored spontaneous circulation received intravenous infusion of either norepinephrine to maintain the mean arterial pressure at 130%of the baseline before ventricular fibrillation or normal saline.Serum diamine oxidase and gastrointestinal ATPase activity were determined,and histopathological examination of the gastrointestinal tract was performed by light and electron microscopy.RESULTS:CPR caused significant injury to the gastrointestinal tract,elevating serum diamine oxidase and causing destruction of intestinal microvillus in control animals.Na^+-K^+ ATPase and Ca^(2+)ATPase activity in gastric tissue were significantly elevated in animals receiving hypertransfusion treatment compared with the control animals.Hypertransfusion also significantly reduced serum diamine oxidase to below control levels after CPR.Moreover,severe injury sustained by the gastrointestinal tissue was markedly ameliorated under hypertransfusion conditions compared with the control animals.CONCLUSIONS:Gastrointestinal injury and abnormal energy metabolism were strikingly evident following CPR.Hypertransfusion inducing hypertension can improve energy metabolism and ameliorate gastrointestinal mucosal injury,indicating that hypothermia significantly ameliorates gastrointestinal injury sustained following cardiac arrest.

Basement interface structural characteristics beneath Jiashi strong earthquake swarm area in Xinjiang, China

The seismic data obtained from high resolution seismic refraction profile in Jiashi strong earthquake swarm area in Xinjiang, China were further processed with ray hit analysis method and more complete basement interface structural characteristics beneath Jiashi strong earthquake swarm area were determined. The results show that there are two clear basement interfaces at the upper crust in Jiashi strong earthquake swarm area. The first one with buried depth ranging from 2.6 km to 3.3 km presents integral and continuous structure, and it appears an inclined plane interface and smoothly rises up toward Tianshan Mountain. The second basement interface with buried depth from 8.5 km to 11.8 km, is the antiquated crystalline basement of Tarim basin. Near the post number of 37 km, the buried depth of the crystalline basement changed abruptly by 2.5 km, which maybe result from an ultra crystalline basement fault. If taking this fault as a boundary, the crystalline basement could be divided into two parts, i.e. the southwestern segment with buried depth about 11.5 km, and the northeastern segment with buried depth approxi-mately from 8.5 km to 9.0 km. That is to say, in each segment, the buried depth changes not too much. The northeast segment rises up as a whole and upheaves slightly from southwest to northeast, which reflects the upper crustal deformation characteristics under the special tectonic background at the northwestern edge of Tarim basin.

Structure Design of Polymer Electro-Optic Modulator with Ultra- Broadband

Using finite element method, lots of calculating focusing on polymer electro-optic modulators with ultra-broadband were done, a few structures were analyzed. Coplanar waveguide electrode system was advanced, a few real examples was given.