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排序方式: 共有215条查询结果,搜索用时 15 毫秒
41.
Damage development in and final failure process of glass fibre winding specimens during biaxial fatigue loading are investigated. The phenomena in nominally defect-free tubes and specimens exhibiting local fibre waviness in one layer are compared. A subset of wound tubes is analysed using non-destructive testing methods, i.e. air-coupled guided waves, thermography, optical fracture analysis by a high-speed camera, and discrete damage monitoring. Air-coupled guided waves are employed for detection of fibre waviness and for monitoring the failure progress initiated by this waviness. Stiffness degradation due to fatigue damage corresponds to a decline in guided wave velocity. Using infrared inspection, the fibre waviness can be detected in an early stage of fatigue life. Non-destructive evaluation reveals that initiation of final failure in the specimens is caused by local fibre waviness. Finally, the effect of local fibre waviness on the S–N curves of the specimens is illustrated. 相似文献
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Robert Khnke Marcus Oliver Ahlers Moritz Alexander Birkelbach Florian Ewald Michael Krueger Imke Fiedler Bjrn Busse Max Heiland Tobias Vollkommer Martin Gosau Ralf Smeets Rico Rutkowski 《International journal of molecular sciences》2021,22(1)
Temporomandibular joint osteoarthritis (TMJ-OA) is a chronic degenerative disease that is often characterized by progressive impairment of the temporomandibular functional unit. The aim of this randomized controlled animal trial was a comparative analysis regarding the chondroregenerative potency of intra-articular stem/stromal cell therapy. Four weeks after combined mechanical and biochemical osteoarthritis induction in 28 rabbits, therapy was initiated by a single intra-articular injection, randomized into the following groups: Group 1: AB Serum (ABS); Group 2: Hyaluronic acid (HA); Group 3: Mesenchymal stromal cells (STx.); Group 4: Mesenchymal stromal cells in hyaluronic acid (HA + STx.). After another 4 weeks, the animals were euthanized, followed by histological examination of the removed joints. The histological analysis showed a significant increase in cartilage thickness in the stromal cell treated groups (HA + STx. vs. ABS, p = 0.028; HA + ST.x vs. HA, p = 0.042; STx. vs. ABS, p = 0.036). Scanning electron microscopy detected a similar heterogeneity of mineralization and tissue porosity in the subchondral zone in all groups. The single intra-articular injection of a stem cell containing, GMP-compliant advanced therapy medicinal product for the treatment of iatrogen induced osteoarthritis of the temporomandibular joint shows a chondroregenerative effect. 相似文献
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Solid-liquid equilibria at ambient pressure and solid-liquid-vapor equilibria at T=303.15 K have been measured in the system ammonia-water-lithium bromide for various initial concentrations of lithium bromide. Liquid phases have been analyzed using ion selective electrodes. A ternary phase diagram of the system at T=303.15 K is provided showing a triple line and several regions in which solid phases of different kind occur. This will restrict considerably the use of these systems as working fluids in absorption machinery.Paper dedicated to Professor Jospeh Kestin. 相似文献
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G Ullrich C Smaczny G Steinkamp J Weber T Welte R Busse TO Wagner 《Canadian Metallurgical Quarterly》1997,51(8):822-827
OBJECTIVE: To better understand the needs of spouses who provide care to spinal cord injury (SCI) survivors, by comparing their self-perceptions and complaints with those of their partners with disabilities and with those of spouses who do not provide care. DESIGN: Survey, including demographics, health concerns questionnaire, and administration of the Center for Epidemiologic Studies Depression Scale (CES-D), the Perceived Stress Scale (PSS), the Life Satisfaction Index (LSI-Z), and the Quality of Life and Individual Needs Questionnaire. SETTING: Two British SCI treatment centers, serving a defined population-based catchment area. PARTICIPANTS: One hundred twenty-four spouses of a longitudinally followed sample of SCI survivors, all of whom had been injured 23 or more years when the study was conducted in 1993. OUTCOME MEASURES: Scores on the above standardized tests, and responses to survey questions. RESULTS: Spouses had more depressive affect (p < .001) than their partners with disabilities, as measured by the CES-D. On the PSS, they exhibited no significant differences. Compared with spouses who were not caregivers, the caregiving spouses reported more physical stress (p = .005), emotional stress (p = .011), burnout (p = .007), fatigue (p = .002), and anger and resentment (p = .029). On the CES-D, they had more symptoms of depressive affect (p = .004) and somatic depression (p = .005). CONCLUSIONS: Spouses of long-term SCI survivors who fulfill a caregiving role report more symptoms of stress and depression than their partners with disabilities and other spouses who are not caregivers. 相似文献
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M Hecker A Blaukat AT Bara W Müller-Esterl R Busse 《Canadian Metallurgical Quarterly》1997,121(7):1475-1481
1. Angiotensin-converting enzyme (ACE) inhibitors exert their cardiovascular effects not only by preventing the formation of angiotensin II (AII), but also by promoting the accumulation of bradykinin in or at the vessel wall. In addition, certain ACE inhibitors have been shown to augment the vasodilator response to bradykinin, presumably by an interaction at the level of the B2 receptor. We have investigated whether this is a specific effect of the ACE inhibitor class of compounds in isolated endothelium-denuded segments of the rabbit jugular vein where bradykinin elicits a constrictor response which is exclusively mediated by activation of the B2 receptor. 2. Moexiprilat and ramiprilat (< or = 3 nM) enhanced the constrictor response to bradykinin three to four fold. Captopril and enalaprilat were less active by approximately one and quinaprilat by two orders of magnitude. Moexiprilat and ramiprilat, on the other hand, had no effect on the constrictor response to AII or the dilator response to acetylcholine. 3. The bradykinin-potentiating effect of the ACE inhibitors was not mimicked by inhibitors of amino-, carboxy-, metallo- or serine peptidases or the synthetic ACE substrate, hippuryl-L-histidyl-L-leucine, at a concentration which almost abolished the residual ACE activity in the vessel wall. In contrast, angiotensin-(1-7) (10 microM), an angiotensin I metabolite, significantly enhanced the constrictor response to bradykinin. 4. Ramiprilat did not alter the binding of [3H]-bradykinin to a membrane fraction prepared from endothelium-denuded rabbit jugular veins or to cultured fibroblasts, and there was no ACE inhibitor-sensitive, bradykinin-induced cleavage of the B2 receptor in cultured endothelial cells. 5. These findings demonstrate that ACE inhibitors selectively potentiate the B2 receptor-mediated vascular effects of bradykinin. Their relative efficacy appears to be independent of their ACE-inhibiting properties and might be related to differences in molecule structure. Moreover, the potentiation of the biological activity of bradykinin by this class of compounds does not seem to be mediated by a shift in affinity of the B2 receptor or a prevention of its desensitization, but may involve an increase in the intrinsic activity of unoccupied B2 receptor molecules. 相似文献
48.
We evaluated the effect of ketamine on the excitability of rabbits vagus nerve by measuring evoked compound action potentials. Histological examination was also done by means of electron microscopy on the nerves incubated in ketamine-Ringer's bicarbonate (RB) solution. We found that 0.05% ketamine causes complete suppression of the compound action potentials. The suppressed compound action potentials by incubating in 0.1% ketamine RB solution recovered completely after washing with ketamine-free RB solution. The electron microscopic examinations revealed no histological changes of the nerves incubated in 0.1% ketamine RB solution. We conclude that ketamine suppresses the nerve excitability causing no histological changes at the concentration below 0.1%. 相似文献
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The paper reports experimental methodology and results of nondestructive evaluation and flaw imaging in cylindrical samples
using surface acoustic waves (SAW) generated with conventional longitudinal wave transducers attached to the sample surface.
A very thin layer of couplant (or even dry coupling) was used to provide efficient SAW generation in the direction normal
to a cylinder element in the frequency range 5—15 MHz. A single B-scan mode was sufficient to inspect a total surface of cylindrical
shafts of ceramic and metal engine valves. A delay of the processing time gate allowed us to analyze any of the successive
SAW revolutions implementing a specific ``transmission B-scan' with a single probe. Amplitude and phase contrast of the B-scans
obtained demonstrate the system capability to detect valve radius deviations of 1 μm and cracked flaws with sizes down to
30 μm. 相似文献