In this study, a vertical axis tidal turbine with flexible blades is investigated. The focus is on analyzing the effect of flexible airfoils types and blade flexibility on turbine net output power. To this end, five d...In this study, a vertical axis tidal turbine with flexible blades is investigated. The focus is on analyzing the effect of flexible airfoils types and blade flexibility on turbine net output power. To this end, five different flexible airfoils （Symmetric and Non-symmetric） are employed. The results show that the use of a thick flexible symmetric airfoil can effectively increase output power compared to that achievable with a conventional rigid blade. Moreover, the use of highly flexible blades, as opposed to less flexible or rigid blades, is not recommended.展开更多
Objective: To estimate the prevalence rates of neural tube defects (NTDs) in Heshun County, Shanxi Province, China by Bayesian smoothing technique. Methods: A total of 80 infants in the study area who were diagnosed w...Objective: To estimate the prevalence rates of neural tube defects (NTDs) in Heshun County, Shanxi Province, China by Bayesian smoothing technique. Methods: A total of 80 infants in the study area who were diagnosed with NTDs were analyzed. Two mapping techniques were then used. Firstly, the GIS software ArcGIS was used to map the crude prevalence rates. Secondly, the data were smoothed by the method of empirical Bayes estimation. Results: The classical statistical approach produced an extremely dishomogeneous map, while the Bayesian map was much smoother and more interpretable. The maps produced by the Bayesian technique indicate the tendency of villages in the southeastern region to produce higher prevalence or risk values. Conclusions: The Bayesian smoothing technique addresses the issue of heterogeneity in the population at risk and it is therefore recommended for use in explorative mapping of birth defects. This approach provides procedures to identify spatial health risk levels and assists in generating hypothesis that will be investigated in further detail.展开更多
The effects of re-crystallization of prednisolone as a poorly water-soluble drug in aqueous surfactant solutions on its dissolution rate were investigated. A significant enhancement was observed for crystal dissolutio...The effects of re-crystallization of prednisolone as a poorly water-soluble drug in aqueous surfactant solutions on its dissolution rate were investigated. A significant enhancement was observed for crystal dissolution rate in hydrophilic surfactants such as tween 80 and sodium lauryl sulfate （SLS）. Differential scanning calorimetry （DSC） and Fourier transform infrared spectroscopy （FT-IR） indicated the existence of both form Ⅰ and Ⅱ ofprednisolone in SLS treated crystals. The FT-IR results also showed that, only form Ⅱ could be detected in prednisolone crystals without surfactant and prednisolone form Ⅲ was produced in tween 80 treated crystals. These results were also confirmed by X-ray （XRD） diffraction and scanning electron microscopy （SEM）. In general, the results indicated that the presence of hydrophilic surfactants could generate forms Ⅱ and Ⅲ of the crystals. These forms would give rlse to the increase of prednisolone＇s dissolution rate owing to their physicochemical instability and more hydrophilic property in comparison with stable polymorph of form Ⅰ.展开更多
文摘In this study, a vertical axis tidal turbine with flexible blades is investigated. The focus is on analyzing the effect of flexible airfoils types and blade flexibility on turbine net output power. To this end, five different flexible airfoils （Symmetric and Non-symmetric） are employed. The results show that the use of a thick flexible symmetric airfoil can effectively increase output power compared to that achievable with a conventional rigid blade. Moreover, the use of highly flexible blades, as opposed to less flexible or rigid blades, is not recommended.
基金Project supported by the National Natural Science Foundation of China (Nos. 40471111 and 70571076)the Ministry of Science and Technology of China (No. 2001CB5103)
文摘Objective: To estimate the prevalence rates of neural tube defects (NTDs) in Heshun County, Shanxi Province, China by Bayesian smoothing technique. Methods: A total of 80 infants in the study area who were diagnosed with NTDs were analyzed. Two mapping techniques were then used. Firstly, the GIS software ArcGIS was used to map the crude prevalence rates. Secondly, the data were smoothed by the method of empirical Bayes estimation. Results: The classical statistical approach produced an extremely dishomogeneous map, while the Bayesian map was much smoother and more interpretable. The maps produced by the Bayesian technique indicate the tendency of villages in the southeastern region to produce higher prevalence or risk values. Conclusions: The Bayesian smoothing technique addresses the issue of heterogeneity in the population at risk and it is therefore recommended for use in explorative mapping of birth defects. This approach provides procedures to identify spatial health risk levels and assists in generating hypothesis that will be investigated in further detail.
文摘The effects of re-crystallization of prednisolone as a poorly water-soluble drug in aqueous surfactant solutions on its dissolution rate were investigated. A significant enhancement was observed for crystal dissolution rate in hydrophilic surfactants such as tween 80 and sodium lauryl sulfate （SLS）. Differential scanning calorimetry （DSC） and Fourier transform infrared spectroscopy （FT-IR） indicated the existence of both form Ⅰ and Ⅱ ofprednisolone in SLS treated crystals. The FT-IR results also showed that, only form Ⅱ could be detected in prednisolone crystals without surfactant and prednisolone form Ⅲ was produced in tween 80 treated crystals. These results were also confirmed by X-ray （XRD） diffraction and scanning electron microscopy （SEM）. In general, the results indicated that the presence of hydrophilic surfactants could generate forms Ⅱ and Ⅲ of the crystals. These forms would give rlse to the increase of prednisolone＇s dissolution rate owing to their physicochemical instability and more hydrophilic property in comparison with stable polymorph of form Ⅰ.
