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This study investigated the relation between piezoelectric behavior and the deformation of trachieds in real time under combined compression and vibration stresses. Scanning electron microscope images were recorded directly into a video recorder. Two types of microscopic destruction were observed in the specimens. With the first type, although a small uprush around the boundary of the annual ring was observed, the specimens were broken only by shearing fracture in the 45° direction. With the second type, the specimens were finally broken by shearing fracture after repeated buckling. In these cases the piezoelectric voltage increased almost linearly in the elastic region, proceeded to the maximal point, and then decreased gradually. Finally a clear peak appeared in the buckling and shearing fracture. There is a curved relation between the specific gravity and the piezoelectric parameter when the influence of voids is considered, and there is a linear relation between the dynamic Young's modulus and the piezoelectric parameter when the stress is considered.Part of this paper was presented at the 46th annual meeting of the Japan Wood Research Society in Kumamoto, April 1996 相似文献
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A Kaya M Aksoy N Basp&#;nar C Y&#;ld&#;z & MB Ataman 《Reproduction in domestic animals》2001,36(3-4):211-215
The influence of melatonin administration to sperm donors on the freezability of ram semen and enzyme leakage through sperm cells during different steps of the cryopreservation process were evaluated in the breeding and non-breeding season. Melatonin implantation to rams in the breeding season improved post-thaw sperm viability and intact acrosome rates without influencing the motility rate (p < 0.05). Likewise, the post-thaw alkaline phosphatase release through sperm cells was significantly lower in the melatonin-treated group in comparison with untreated controls (p < 0.05). In the non-breeding season, melatonin administration enhanced intact acrosome rates (p < 0.05) and reduced aspartate aminotransferase activity (p < 0.05) post-thaw in the offseason ejaculates. Melatonin implantation twice in the breeding and non-breeding season did not produce any further improvement in the post-thaw sperm parameters in the non-breeding season ejaculates. It was concluded that melatonin administration to sperm donors improved freezability of ram semen collected from these rams and reduced enzyme leakage through sperm cells during cryopreservation. 相似文献
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Ataman Kose Nurullah Gunay Ali R. Ocak Abdullah T. Demiryurek 《Pesticide biochemistry and physiology》2010,97(3):249-255
Recent several studies have reported that oxidative stress could be an important component of the mechanism of cardiotoxicity due to organophosphate-induced toxicity. The aim of this study is to evaluate the oxidative and antioxidative parameters in cardiac toxicity of organophosphate poisoning, and determine the effects of atropine and pralidoxime on this parameters. The experimental groups were randomly divided into five groups as control (corn oil), dichlorvos (30 mg/kg), atropine (10 mg/kg), pralidoxime (40 mg/kg), and atropine (10 mg/kg) + pralidoxime (40 mg/kg) groups. Serum cholinesterase levels were suppressed with dichlorvos, and these reductions were inhibited with atropine and/or pralidoxime pretreatment. Serum, but not cardiac, total free sulfhydryl groups and paraoxonase activities were significantly increased in the pralidoxime group when compared to the control group. Serum arylesterase activities were elevated in the dichlorvos, atropine, pralidoxime, and atropine + pralidoxime groups when compared to the control group (P < 0.05). Total oxidant status, oxidative stress index, malondialdehyde and catalase activities in serum and cardiac tissues were not markedly different between the groups. No significant changes were also observed with cardiac myeloperoxidase and serum ceruloplasmin activities. In conclusion, these results showed that acute dichlorvos administration did not cause marked cardiac damage, and oxidative stress probably does not play a major role in dichlorvos-induced poisoning. On the other hand, especially pralidoxime treatment markedly increased the serum total free sulfhydryl groups, paraoxonase and arylesterase activities. However, the underlying mechanisms for these changes are not exactly known. 相似文献
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Kenan oyan Nuri Bap&#x;nar Mustafa Numan Bucak P&#x;nar Peker Akal&#x;n Mehmet Bozkurt Ataman Ali Doan
mür ükrü Güngr Sad&#x;k Küükgünay Birol
zkalp Serpil Sar&#x;zkan 《Research in veterinary science》2010,89(3):426-431
The aim of this study was to investigate the effects of methionine and dithioerythritol, added to the Tris extender, on ram sperm motility and LPO (lipid peroxidation) and antioxidant capacities during liquid storage up to 72 h at 5 °C. Ejaculates collected from five Merino rams, were evaluated and pooled at 37 °C. This study included two experiments. In experiment 1, each pooled ejaculate was divided into four equal aliquots and diluted (37 °C) with the base extender, containing 0 (control), 1, 2 and 4 mM methionine, at a final concentration of approximately 4 × 108 sperms/ml (single step dilution), in a 15-ml plastic centrifuge tube. In experiment 2, dithioerythritol, at concentrations of 0 (control), 0.5, 1 and 2 mM, was used as an additive in the extender, and the procedure explained above was applied for the division of aliquots and the dilution of semen. Diluted semen samples were kept in glass tubes and cooled from 37 to 5 °C in a cold cabinet, and maintained at 5 °C. Sperm motility and LPO and total glutathione (GSH) and glutathione peroxidase (GPx) capacities were determined at 5 °C for periods of 0, 24, 48 and 72 h of liquid storage.The extender supplemented with 1 mM methionine led to higher motility percentages (77.0 ± 1.2%), in comparison to the control group (66.0 ± 4.9%), during 72 h of liquid storage (P < 0.05). As regards dithioerythritol, it did not statistically improve the motility rates for any of the storage times at 5 °C. In biochemical assays, differences in LPO levels between the groups with antioxidants and the control groups were not statistically significant. Compared to the control group, no significant difference was observed in GSH and GPx activities following the addition of methionine, during 72 h of storage. Total GSH and GPx activities did not increase significantly upon supplementation with 0.5 and 1 mM of dithioerythritol, compared to the control group, at any of the time points (P > 0.05). Dithioerythritol at 2 mM led (P < 0.01) to elevating GSH activity, compared to the control group, during 72 h of liquid storage. GPx activity was approximately 10 times higher for 2 mM of dithioerythritol (P < 0.001), compared to that of the control group at all time points.The question regarding the sustainability of sperm survival, LPO and antioxidant capacities following liquid storage of semen remains unanswered. Further studies are required for a better understanding of the biochemical changes and to obtain more information on the determination of lipid peroxidation and antioxidant capacities during cooled storage of ram semen. 相似文献
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This study investigated and clarified the relation between the piezoelectric voltage and microscopic fracture of hinoki (Chamaecyparis obtura Endl.), in particular the deformation of the cross-sectional wall of the tracheid in linear-elastic regions under combined compression and vibration stresses. The piezoelectric voltage-deformation (P-D) curve consisted of a linear region starting from the origin followed by a convex curved region. The linear region of theP-D curve was only about 60% of that of the load-displacement (L-D) curve. By applying combined stresses to a specimen, the cross-sectional walls of the tracheid were deformed mainly at the radial walls. When a tracheid was regarded approximately as a hexagonal prism, the elastic buckling stress of the radial wall was estimated from scanning electron microscope images and our method based on a modification of the Gibson and Ashby method. As a result, it was estimated that the elastic buckling stress was only about 80% of the stress at the proportional limit of theP-D curve. It is found that there are two consecutive regions before the proportional limit of theP-D curve: One is the region up to the spot where the radial cell wall generates the elastic buckling, and the other is the region starting from the end of the aforementioned region up to the proportional limit of theP-D curve.Part of this paper was presented at the 47th annual meeting of the Japan Wood Research Society, Kochi, April 3–5, 1997 相似文献
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This study was focused not only at the assessment of effects of different sewage sludge application rates on vegetative parameters and yield of raspberry (Rubus ideaus L.) but also heavy metal accumulation in the soil and raspberry leaves. A three-year field study was set up in a completely randomized block design with five sewage sludge application rates (0.0, 2.5, 5.0, 7.5 and 10.0?kg of dry matter per plant) and three replications. One-year-old, virus free ‘Heritage’ saplings were used for the experiment. The results of this study clearly indicated that the sewage sludge application is an effective mean for improvement of vegetative growth, yield, soil and plant chemical properties of raspberry in light textured soils. In addition to macro-element contents, sewage sludge application also caused significant changes in micro-element content of soils. No adverse effects of these increases were observed on plants throughout the experimental period. The most effective application rate was found as 7.5?kg per plant for this ecological condition. It can be concluded that when properly treated and applied to farmland sewage sludge is not only disposed economically but also improved vegetative growth and yield of raspberry. 相似文献