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Copyright of Large Electric Machine & Hydraulic Turbine is the property of Large Electric Machine & Hydraulic Turbine Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Kunming Medical University / Kunming Yike Daxue Xuebao is the property of Kunming Medical Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The performance and stability of turbine are easily affected by the complex turbulence such as clearance vortex and leakage flow. For the purpose of analyzing the influence of seal clearance on the energy features and interior flow characteristics of Francis turbine, with referencing N-S equation and SST turbulence model, the three-dimensional steady flow in the full flow passage of the Francis turbine model under five schemes of clearance were calculated. Four flow rates were chosen as: 0.6 Qd, 0.8 Qd, Qd and 1.2 Qd. Five schemes of clearance size were selected of 0.4, 0.6, 0.8, 1.0 and 1.3 mm. By comparing the effects of different clearance schemes on the efficiency and volume loss of Francis turbine, the relationship between clearance and turbine performance was analyzed based on the characteristics of internal fluid field, and the calculation results showed that by increasing the size of clearance, the turbine efficiency could be reduced, and the leakage of the turbine indicated an upward trend. When the turbine operated at a small flow rate of 0.6 Qd, the clearance appeared the most obvious influence on the energy features of the turbine. With the increase of clearance, the leakage ratio increased from 0.18% to 0.54%, and the efficiency decreased by 4.1 percentage points. At the flow rate of 1.2 Qd, the clearance presented the least influence on the energy features of the turbine. The leakage ratio increased from 0.07% to 0.27%, and the efficiency decreased by 1.38 percentage points when the clearance was increased. If the turbine was operated at small flow rates of 0.6 Qd and 0.8 Qd, the clearance increased, and the internal fluid fields inside both the clearance and the draft tube deteriorated slightly. The average velocity in the clearance increased gradually, and the eddy current intensity in the inlet and outlet pressure chambers of the clearance increased little by little, the volume of vortex rope in the center of draft tube inlet was increased simultaneously. If the unit was operated at a large flow rate of 1.2 Qd, with the clearance increased from 0.4 mm to 1.3 mm, the characteristics of fluid field inside clearance and the pressure distribution on the suction surface of the runner blades, also the fluid field inside the draft tube were all improved. The area of negative pressure zone on suction surface of runner blades decreased, and the volume of the cavity vortex rope at the inlet center of the draft tube decreased, the streamline inside the draft tube also tended to be smooth. This study could provide an effective reference for the design of seal clearance of Francis turbine. [ABSTRACT FROM AUTHOR]

BACKGROUND: The vascular endothelial growth factor (VEGF) plays an important role in the development and formation of blood vessels. Up to now, there are few reports about the treatment of postoperative complications of vascular anastomosis surgery by mcrosutures with VEGF in China. OBJECTIVE: To synthesiize microsutures with VEGF and to evaluate its effect in revascularization following small vessel anastomosis. METHODS: The method of emulsification-diffusion was use to produce biodegradable polymer polylactic acid/glycolic acid (PLGA) copolymer microparticles containing VEGF, and then, the microparticles were added into microsutures to prepare microsutures with VEGF. Ninety Sprague-Dawley rats were enrolled to make animal models of caudal artery anastomosis using microsutures with VEGF in experimental group and microsutures alone in control group. Complications and VEGF level in the peripheral blood were detected and hematoxylin-eosin staining at the anastomotic site was performed at 2, 12 hours, 1, 3, 7 days after anastomosis. RESULTS AND CONCLUSION: (1) Postoperative complications: The postoperative incidence of skin necrosis was significantly lower in the experimental group than the control group (P < 0.05). (2) VEGF level: Compared with the control group, the peripheral blood VEGF level was significantly higher in the experimental group at each time point after operation (P < 0.05). (3) Hematoxylin-eosin staining: In the experimental group, proliferated endothelial cells were seen near the anastomotic site at 1 day after anastomosis; there were a large number of proliferated endothelial cells and subcutaneous tissues covering the sutures completely at 3 days after anastomosis; and endothelial cells and internal elastic lamina were completely repaired, smooth muscle cells proliferated further, and the outer membrane returned to normal at 1 week after anastomosis. In the control group, cell degeneration and necrosis were seen near the anastomotic suture, and only adventitial cells infiltrated and exhibited a traumatic proliferative response at 1 day after anastomosis; neonatal endothelial cells appeared in the exfoliated area of the endothelial cells, grew and migrated, and there was a few endothelial cells covering the anastomotic site at 3 days after anastomosis; and newborn endothelial cells got over the anastomotic crack and covered the suture. To conclude, microsutures with sustained-release VEGF microparticles can promote endothelial cell regeneration in rats at the anastomotic site. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)