Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-...Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-band vibration and sound radiation reduction effect of vibration isolation masses located in a base structure was researched.The influence of the blocking mass’ cross-section size and shape parameters and the layout location of the base isolation performance was discussed.Furthermore,the effectiveness of rigid vibration isolation design of the base structure was validated.The results show that the medium and high frequency vibration and sound radiation of a power cabin are effectively reduced by a blocking mass.Concerning weight increment and section requirement,suitably increasing the blocking mass size and section height and reducing section width can result in an efficiency-cost ratio.展开更多
The present study aims to determine the influence of microvascular dysfunction (MVD) in the prognosis of patients presenting isolated left bundle branch block (LBBB). Methods: We studied 30 patients (pts), 22 males, 8...The present study aims to determine the influence of microvascular dysfunction (MVD) in the prognosis of patients presenting isolated left bundle branch block (LBBB). Methods: We studied 30 patients (pts), 22 males, 8 females, mean age 57 ± 4 years, with isolated LBBB, with a mean follow up of 48 ± 6 months. The control group consisted of 20 healthy individuals, 12 males, mean age 52 ± 10 years. Both groups were screened for cardiovascular risk factors (RF);they also had an echocardiogram and Coronary CT Scan, ruling out both structural heart disease and obstructive lesions of the epicardial coronary arteries. A myocardial perfusion study was then performed, with two groups emerging according to these results: Group A, 8 pts (26%), with reversible perfusion defects, in which the diagnosis of MVD was suspected, and Group B, 22 pts (74%), with either normal perfusion or minor septal/apical reversible defects (related to LBBB). All Group A pts, and 9 of the Group B pts, underwent coronary arteriography, with intracoronary acetylcholine and nitroglycerine infusion, thus evaluating vasomotor response as endothelium dependent (acetylcholine) or endothelium independent (nitroglycerine). During follow up, we reviewed functional class, 12 lead ECG and echocardiogram on a yearly basis. Results: All Group A patients had an abnormal acetylcholine response;only three of them had abnormal response to nitroglycerine infusion, suggesting endothelium dependent MVD. Of those in Group B, only one patient had abnormal acetylcholine response. At the end of the follow up period, 3 pts (37%) in Group A, showed functional class decrease vs 5 pts (22%) of those in Group B. In Group A, a significant increase of End Diastolic Left Ventricle Diameter (EDLVD) was found (51.6 ± 3.6 vs 59.3 ± 6.8 mm;p < 0.05) with significant decrease in LVEF (62 ± 4.8 vs 46% ± 3.7%, p variation. In neither group major complications (death, heart failure admissions) were found. Conclusion: We confirm the association between MVD and a worse clinical prognosis in isolated LBBB patients. Repeated ischemia and myocardial fibrosis are highlighted as possible physiopathological mechanisms, precluding a progressive left ventricular function decrease, with a higher mortality and arrhythmia risk. Endothelial function preserving strategies, both preventive and therapeutic, might be useful in improving LBBB with MVD patient’s prognosis.展开更多
[Objective] The aim of this study was to manually isolate the microstructures such as ovule and embryo of Capsella bursa-pastoris (L.) Medic. by the non-enzymatic method. [Method] With the gum block and dissecting mic...[Objective] The aim of this study was to manually isolate the microstructures such as ovule and embryo of Capsella bursa-pastoris (L.) Medic. by the non-enzymatic method. [Method] With the gum block and dissecting microscope, its floral characteristics, ovule and embryo were manually isolated and observed by the non-enzymatic method. [Result] C. bursa-pastoris had four calyces, four petals, tetradynamous stamen and silicle, while its embryogenesis contained globular embryo, heart-shaped embryo and torpedo-shaped embryo. [Conclusion] The microstructures such as ovule and embryo of plants become easier to be isolated manually with the viscosity of gum block, which has small damage on embryo or disadvantages of keeping original shapes, and also can used in multi fields studies. This test can also be accomplished in labs with poor experiment facilities.展开更多
基金Supported by the International Cooperation Program under Grant No.2007DFR80340the National Natural Science Foundation of China under Grant No.50779007
文摘Rigid blocking masses are located in the typical base structure of a power cabin based on the impedance mismatch principle.By combining the acoustic-structural coupling method and statistical energy analysis,the full-band vibration and sound radiation reduction effect of vibration isolation masses located in a base structure was researched.The influence of the blocking mass’ cross-section size and shape parameters and the layout location of the base isolation performance was discussed.Furthermore,the effectiveness of rigid vibration isolation design of the base structure was validated.The results show that the medium and high frequency vibration and sound radiation of a power cabin are effectively reduced by a blocking mass.Concerning weight increment and section requirement,suitably increasing the blocking mass size and section height and reducing section width can result in an efficiency-cost ratio.
文摘The present study aims to determine the influence of microvascular dysfunction (MVD) in the prognosis of patients presenting isolated left bundle branch block (LBBB). Methods: We studied 30 patients (pts), 22 males, 8 females, mean age 57 ± 4 years, with isolated LBBB, with a mean follow up of 48 ± 6 months. The control group consisted of 20 healthy individuals, 12 males, mean age 52 ± 10 years. Both groups were screened for cardiovascular risk factors (RF);they also had an echocardiogram and Coronary CT Scan, ruling out both structural heart disease and obstructive lesions of the epicardial coronary arteries. A myocardial perfusion study was then performed, with two groups emerging according to these results: Group A, 8 pts (26%), with reversible perfusion defects, in which the diagnosis of MVD was suspected, and Group B, 22 pts (74%), with either normal perfusion or minor septal/apical reversible defects (related to LBBB). All Group A pts, and 9 of the Group B pts, underwent coronary arteriography, with intracoronary acetylcholine and nitroglycerine infusion, thus evaluating vasomotor response as endothelium dependent (acetylcholine) or endothelium independent (nitroglycerine). During follow up, we reviewed functional class, 12 lead ECG and echocardiogram on a yearly basis. Results: All Group A patients had an abnormal acetylcholine response;only three of them had abnormal response to nitroglycerine infusion, suggesting endothelium dependent MVD. Of those in Group B, only one patient had abnormal acetylcholine response. At the end of the follow up period, 3 pts (37%) in Group A, showed functional class decrease vs 5 pts (22%) of those in Group B. In Group A, a significant increase of End Diastolic Left Ventricle Diameter (EDLVD) was found (51.6 ± 3.6 vs 59.3 ± 6.8 mm;p < 0.05) with significant decrease in LVEF (62 ± 4.8 vs 46% ± 3.7%, p variation. In neither group major complications (death, heart failure admissions) were found. Conclusion: We confirm the association between MVD and a worse clinical prognosis in isolated LBBB patients. Repeated ischemia and myocardial fibrosis are highlighted as possible physiopathological mechanisms, precluding a progressive left ventricular function decrease, with a higher mortality and arrhythmia risk. Endothelial function preserving strategies, both preventive and therapeutic, might be useful in improving LBBB with MVD patient’s prognosis.
基金Supported by Natural Science Foundation (No. 30770124)SRTP Fund from Henan University of Science and Technology~~
文摘[Objective] The aim of this study was to manually isolate the microstructures such as ovule and embryo of Capsella bursa-pastoris (L.) Medic. by the non-enzymatic method. [Method] With the gum block and dissecting microscope, its floral characteristics, ovule and embryo were manually isolated and observed by the non-enzymatic method. [Result] C. bursa-pastoris had four calyces, four petals, tetradynamous stamen and silicle, while its embryogenesis contained globular embryo, heart-shaped embryo and torpedo-shaped embryo. [Conclusion] The microstructures such as ovule and embryo of plants become easier to be isolated manually with the viscosity of gum block, which has small damage on embryo or disadvantages of keeping original shapes, and also can used in multi fields studies. This test can also be accomplished in labs with poor experiment facilities.
