Estrogen produces several beneficial effects in healthy neurological tissues and exhibits cardioprotective effects.Hormone therapy has been widely used to treat menopausal estrogen deficiency for more than 80 years.De...Estrogen produces several beneficial effects in healthy neurological tissues and exhibits cardioprotective effects.Hormone therapy has been widely used to treat menopausal estrogen deficiency for more than 80 years.Despite high initial expectations of cardioprotective effects,there has been substantial distrust following important randomized clinical trials,such as the Women’s Health Initiative.Subsequently,the timing of treatment in relation to the onset of menopause came under consideration and led to the proposal of the timing hypothesis,that early initial treatment is important,and benefits are lost as the timing since menopause becomes prolonged.Subsequent analyses of the Women’s Health Initiative data,together with more recent data from randomized and observational trials,consistently show reductions in coronary heart disease and mortality in younger menopausal women.Regarding cognitive function,the timing hypothesis is consistent with observations from basic and animal studies.There is some clinical evidence to support the benefits of hormonal therapy in this context,though skepticism remains due to the paucity of clinical trials of substantial length in younger menopausal women.It is likely that the effects of estrogens on cognitive performance are due to rapid mechanisms,including mechanisms that influence Ca2+homeostasis dynamics,provide protection in a hostile environment and reduce inflammatory signals from neural tissues.In the future,inflammatory profiles accounting for early signs of pathological inflammation might help identify the‘window of opportunity’to use estrogen therapy for successful cognitive protection.展开更多
The cold-island effect of urban wetlands has received increasing attention in recent years due to its important role in the alleviation of urban heat islands.Hangzhou,a representative rapidly urbanizing city with rich...The cold-island effect of urban wetlands has received increasing attention in recent years due to its important role in the alleviation of urban heat islands.Hangzhou,a representative rapidly urbanizing city with rich wetlands in China,was selected as a case study for researching the changes that the urban wetlands have undergone and their impact on the urban thermal environment.Land surface temperature(LST) was acquired from the thermal infrared data of Landsat 5 Thematic Mapper(TM) images in 1990,1995,2000,2006,and 2010,using the single-channel method.The results are as follows:1) considering the changes in land use,the urban wetlands located to the west of Hangzhou have decreased significantly during 1990–2010 because of rapid urbanization.In the Xixi Wetland,the change in land use was relatively small and most of the water body and vegetation were preserved.However,to the east of the Xixi Wetland,large areas of water body and vegetation have been replaced by built-up land as a result of the urbanization process;2) considering the change in LST,it was found from land surface temperature retrieval that the changing spatial pattern of the thermal field was highly correlated with land use changes.Low temperature regions of the eastern Xixi Wetland were gradually eroded by high temperature regions,and the centroid of the heat island in East Xixi was found to be constantly shifting westward.In addition,the difference in LST between the Xixi Wetland and East Xixi has increased;3) considering the impact factors for this area,land use structure and patch shape were found to have a significant impact on LST,shown by the results of multiple linear stepwise regressions.Increasing the size of the wetlands in urban planning is considered to be the most effective measure in alleviating the urban heat island effect.Moreover,reducing the spatial complexity of landscape patches also contributes to the alleviation of the urban heat island effect.展开更多
A lead-free Sn-3.5Ag solder was prepared by rapid solidification technology. The high solidification rate, obtained by rapid cooling, promotes nucleation, and suppresses the growth of Ag3Sn intermetallic compounds （I...A lead-free Sn-3.5Ag solder was prepared by rapid solidification technology. The high solidification rate, obtained by rapid cooling, promotes nucleation, and suppresses the growth of Ag3Sn intermetallic compounds （IMCs） in Ag-rich zone, yielding fine Ag3Sn nanoparticulates with spherical morphology in the matrix of the solder. The large amount of tough homogeneously-dispersed IMCs helps to improve the surface area per unit volume and obstructs the dislocation lines passing through the solder, which fits with the dispersion-strengthening theory. Hence, the rapidly-solidified Sn-3.5Ag solder exhibits a higher rnicrohardness when compared with a slowly-solidified Sn-3.5Ag solder.展开更多
Development of graphene field effect transistors （GFETs） faces a serious challenge of graphene interface to the dielectric material. A single layer of intrinsic graphene has an average sheet resistance of the order ...Development of graphene field effect transistors （GFETs） faces a serious challenge of graphene interface to the dielectric material. A single layer of intrinsic graphene has an average sheet resistance of the order of 1-5 kΩ/□. The intrinsic nature of graphene leads to higher contact resistance yielding into the outstanding properties of the material. We design a graphene matrix with minimized sheet resistance of 0.185 kΩ/□ with Ag contacts. The developed matrices on silicon substrates provide a variety of transistor design options for subsequent fabrication. The graphene layer is developed over 400 nm nickel in such a way as to analyze hypersensitive electrical properties of the interface for exfoliation. This work identifies potential of the design in the applicability of few-layer GFETs with less process steps with the help of analyzing the effect of metal contact and post-process anneMing on its electrical fabrication.展开更多
Since the last decade deep brain stimulation has been proposed as an alternative treatment for patients who do not become seizure-free with the current pharmacological treatments and cannot undergo resective surgical ...Since the last decade deep brain stimulation has been proposed as an alternative treatment for patients who do not become seizure-free with the current pharmacological treatments and cannot undergo resective surgical procedure. However, the optimal stimulation parameters remain undetermined and active research in humans and animals is necessary. The present study was designed to investigate the effect of unilateral Low Frequency Stimulation (LFS) of hippocampus on seizure development by using the hippocampal rapid kindling method (hRK) in rats. We used male Wistar rats implanted with electrodes in the ventral hippocampus. All rats underwent hRK (biphasic square wave pulses, 20 Hz for 10 seconds) during three consecutive days (twelve stimulations per day). The control group (hRK;n = 6) received only RK stimulus, while the treated group (LFS-hRK;n = 8) received also LFS (biphasic square wave pulses, 1 Hz for 30 seconds) immediately before the RK stimulus, during three consecutive days. At the end of behavioral testing on day 3, 62% (P < 0.05) of the animals receiving LFS treatment were still not fully kindled staying in stages 0-III (P < 0.01). The number of stimulations needed to achieve generalized seizures (stage IV-V of Racine scale) was significantly higher (P < 0.05) in the LFS group with respect to control group. No significant differences in the cumulative daily afterdischarge duration were observed between both groups. These findings suggest that preemptive LFS can significantly decrease the incidence of hippocampus-kindled seizures and delay the progression and secondary generalization of focal seizures.展开更多
Effects of rolled leaf gene Rl（t） on grain quality characters of hybrid rice were analyzed by using three pairs of rolled leaf near-isogenic lines under two fertilizer treatments. Under normal fertilizer level （e.g...Effects of rolled leaf gene Rl（t） on grain quality characters of hybrid rice were analyzed by using three pairs of rolled leaf near-isogenic lines under two fertilizer treatments. Under normal fertilizer level （e.g. 450 kg urea per ha）, head rice rates and milled rice recovery of rolled leaf hybrids were significantly higher than those of corresponding non-rolled crosses, while the chalky rice rate and chalkiness were all lower. Of the RVA profiles, the peak viscosity, the hot paste viscosity and the breakdown viscosity of the rolled were all higher than those of the corresponding non-rolled ones to various degrees. Increasing fertilizer application for promoting panicle development increased the brown, milled and head rice rates except for Shanyou 63, furthermore, significant difference of head rice rates existed between the rolled leaf Shanyou 559 and Shanyou 559; while the peak viscosity, the hot paste viscosity and the breakdown viscosity all decreased to different levels; changes of values of other characters had no apparent regularity. It suggested that Rl（t） could improve rice quality under certain conditions.展开更多
目的探讨快速康复方案在继发性甲状旁腺功能亢进患者中的应用效果。方法选取2020年1月至2023年6月于河北医科大学第三医院行甲状旁腺切除术治疗的200例继发性甲状旁腺功能亢进患者为研究对象,按照随机数字表法将其分为观察组与对照组,各...目的探讨快速康复方案在继发性甲状旁腺功能亢进患者中的应用效果。方法选取2020年1月至2023年6月于河北医科大学第三医院行甲状旁腺切除术治疗的200例继发性甲状旁腺功能亢进患者为研究对象,按照随机数字表法将其分为观察组与对照组,各100例。观察组给予快速康复策略,对照组给予常规护理。比较两组手术时间、住院时间、术后卧床时间、住院费用。比较两组不同时间点C反应蛋白(CRP)、白细胞介素-1(IL-1)、转化生长因子-β_(1)(TGF-β_(1))、血钙、视觉模拟评分法(VAS)评分、医学研究理事会评估表(MRC)评分、体重指数。结果两组手术时间比较,差异无统计学意义(P>0.05);观察组住院时间、术后卧床时间短于对照组,住院费用低于对照组,差异有统计学意义(P<0.05)。两组术后1、3、5 d CRP、IL-1、TGF-β_(1)水平均高于术前,术后3、5 d CRP、IL-1、TGF-β_(1)水平低于术1 d,术后5 d CRP、IL-1、TGF-β_(1)水平低于术后3 d,差异有统计学意义(P<0.05);观察组术后3、5 d CRP、IL-1、TGF-β_(1)水平均低于对照组,差异有统计学意义(P<0.05)。两组术后1、3、5 d血钙水平均低于术前,差异有统计学意义(P<0.05);观察组术后1、3、5 d血钙水平均高于对照组,差异有统计学意义(P<0.05)。两组术后3、5 d VAS评分均低于术后1 d(P<0.05);观察组术后1、3、5 d VAS评分低于对照组,差异有统计学意义(P<0.05)。术前与术后,两组MRC评分、体重指数比较,差异无统计学意义(P>0.05)。观察组总并发症发生率低于对照组,差异有统计学意义(P<0.05)。结论快速康复策略在继发性甲状旁腺功能亢进患者中有利于控制炎症和降低并发症发生率,对促进早期康复具有重要意义。展开更多
In this paper, the unsteady effect of airflow is introduced into the calculation of aircraft maneuver load, and the results are compared with those obtained by quasi-steady method. Taking the steep pitch maneuver of a...In this paper, the unsteady effect of airflow is introduced into the calculation of aircraft maneuver load, and the results are compared with those obtained by quasi-steady method. Taking the steep pitch maneuver of an aircraft as an example, two methods are used to calculate the aircraft response after the rudder input is given according to the specifications. The calculation results show that if the peak overload of the aircraft is the same, the horizontal tail load increases by about 1% when the unsteady effect of the airflow is taken into account. If the rudder input of the two methods is the same, the unsteady calculation method will increase more. At the same time, the calculation shows that the bigger the deflection speed of rudder surface is, the bigger the difference between them is. Therefore, in order to improve the design quality of aircraft, it is necessary to introduce the unsteady effect into the calculation of loads in the detailed design stage of aircraft.展开更多
Foil powders of Al 5.0 Cr 4.0 Y 1.5 Zr (%) were prepared by using a multi stage atomization rapid solidification powder making device. The obtained powders were exposed thermally at various temperatures. Variation of ...Foil powders of Al 5.0 Cr 4.0 Y 1.5 Zr (%) were prepared by using a multi stage atomization rapid solidification powder making device. The obtained powders were exposed thermally at various temperatures. Variation of microstructures and properties of the alloy powders was investigated by micro hardness measurement, X ray diffraction, differential thermal analysis, and transmission electron microscopy with energy disperse X ray analyses. The results show that cubic Al 20 Cr 2Y ( a = 1.437?nm) and metastable Ll 2 Al 3Zr (FCC, a = 0.405?1?nm) or equilibrium DO 23 Al 3Zr (tetragonal structure, a = 0.409?1?nm, b = 1.73?0?nm) are main second phases precipitated from supersaturated solid solution of the rapidly solidified foil powders during thermal exposure. The cubic dispersion precipitates prior to the two other Al 3Zr type intermetallic phases in the course of the decomposition. Precipitation of incoherent Al 20 Cr 2Y results in softening of foil powder, and coherent Ll 2 Al 3Zr has intensive precipitation strengthening effect. The Al 20 Cr 2Y phase is structurally stable, but it is prone to coarsen and polygonize above 450?℃. Both Al 3Zr type intermetallic phases have much smaller coarsening rate than Al 20 Cr 2Y at temperature higher than 450?℃. These two phases are able to keep their fine spherical morphologies up to 550?℃, but Al 3Zr transforms into DO 23 structure from Ll 2 structure during thermal exposure above 550?℃.展开更多
文摘Estrogen produces several beneficial effects in healthy neurological tissues and exhibits cardioprotective effects.Hormone therapy has been widely used to treat menopausal estrogen deficiency for more than 80 years.Despite high initial expectations of cardioprotective effects,there has been substantial distrust following important randomized clinical trials,such as the Women’s Health Initiative.Subsequently,the timing of treatment in relation to the onset of menopause came under consideration and led to the proposal of the timing hypothesis,that early initial treatment is important,and benefits are lost as the timing since menopause becomes prolonged.Subsequent analyses of the Women’s Health Initiative data,together with more recent data from randomized and observational trials,consistently show reductions in coronary heart disease and mortality in younger menopausal women.Regarding cognitive function,the timing hypothesis is consistent with observations from basic and animal studies.There is some clinical evidence to support the benefits of hormonal therapy in this context,though skepticism remains due to the paucity of clinical trials of substantial length in younger menopausal women.It is likely that the effects of estrogens on cognitive performance are due to rapid mechanisms,including mechanisms that influence Ca2+homeostasis dynamics,provide protection in a hostile environment and reduce inflammatory signals from neural tissues.In the future,inflammatory profiles accounting for early signs of pathological inflammation might help identify the‘window of opportunity’to use estrogen therapy for successful cognitive protection.
基金Under the auspices of National Natural Science Foundation of China(No.41101039,41371068)
文摘The cold-island effect of urban wetlands has received increasing attention in recent years due to its important role in the alleviation of urban heat islands.Hangzhou,a representative rapidly urbanizing city with rich wetlands in China,was selected as a case study for researching the changes that the urban wetlands have undergone and their impact on the urban thermal environment.Land surface temperature(LST) was acquired from the thermal infrared data of Landsat 5 Thematic Mapper(TM) images in 1990,1995,2000,2006,and 2010,using the single-channel method.The results are as follows:1) considering the changes in land use,the urban wetlands located to the west of Hangzhou have decreased significantly during 1990–2010 because of rapid urbanization.In the Xixi Wetland,the change in land use was relatively small and most of the water body and vegetation were preserved.However,to the east of the Xixi Wetland,large areas of water body and vegetation have been replaced by built-up land as a result of the urbanization process;2) considering the change in LST,it was found from land surface temperature retrieval that the changing spatial pattern of the thermal field was highly correlated with land use changes.Low temperature regions of the eastern Xixi Wetland were gradually eroded by high temperature regions,and the centroid of the heat island in East Xixi was found to be constantly shifting westward.In addition,the difference in LST between the Xixi Wetland and East Xixi has increased;3) considering the impact factors for this area,land use structure and patch shape were found to have a significant impact on LST,shown by the results of multiple linear stepwise regressions.Increasing the size of the wetlands in urban planning is considered to be the most effective measure in alleviating the urban heat island effect.Moreover,reducing the spatial complexity of landscape patches also contributes to the alleviation of the urban heat island effect.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50401003), the Natural Science Foundation of Tianjin City (No. 033608811) and Fok Ying Tong Education Foundation (No. 104015).
文摘A lead-free Sn-3.5Ag solder was prepared by rapid solidification technology. The high solidification rate, obtained by rapid cooling, promotes nucleation, and suppresses the growth of Ag3Sn intermetallic compounds （IMCs） in Ag-rich zone, yielding fine Ag3Sn nanoparticulates with spherical morphology in the matrix of the solder. The large amount of tough homogeneously-dispersed IMCs helps to improve the surface area per unit volume and obstructs the dislocation lines passing through the solder, which fits with the dispersion-strengthening theory. Hence, the rapidly-solidified Sn-3.5Ag solder exhibits a higher rnicrohardness when compared with a slowly-solidified Sn-3.5Ag solder.
文摘Development of graphene field effect transistors （GFETs） faces a serious challenge of graphene interface to the dielectric material. A single layer of intrinsic graphene has an average sheet resistance of the order of 1-5 kΩ/□. The intrinsic nature of graphene leads to higher contact resistance yielding into the outstanding properties of the material. We design a graphene matrix with minimized sheet resistance of 0.185 kΩ/□ with Ag contacts. The developed matrices on silicon substrates provide a variety of transistor design options for subsequent fabrication. The graphene layer is developed over 400 nm nickel in such a way as to analyze hypersensitive electrical properties of the interface for exfoliation. This work identifies potential of the design in the applicability of few-layer GFETs with less process steps with the help of analyzing the effect of metal contact and post-process anneMing on its electrical fabrication.
文摘Since the last decade deep brain stimulation has been proposed as an alternative treatment for patients who do not become seizure-free with the current pharmacological treatments and cannot undergo resective surgical procedure. However, the optimal stimulation parameters remain undetermined and active research in humans and animals is necessary. The present study was designed to investigate the effect of unilateral Low Frequency Stimulation (LFS) of hippocampus on seizure development by using the hippocampal rapid kindling method (hRK) in rats. We used male Wistar rats implanted with electrodes in the ventral hippocampus. All rats underwent hRK (biphasic square wave pulses, 20 Hz for 10 seconds) during three consecutive days (twelve stimulations per day). The control group (hRK;n = 6) received only RK stimulus, while the treated group (LFS-hRK;n = 8) received also LFS (biphasic square wave pulses, 1 Hz for 30 seconds) immediately before the RK stimulus, during three consecutive days. At the end of behavioral testing on day 3, 62% (P < 0.05) of the animals receiving LFS treatment were still not fully kindled staying in stages 0-III (P < 0.01). The number of stimulations needed to achieve generalized seizures (stage IV-V of Racine scale) was significantly higher (P < 0.05) in the LFS group with respect to control group. No significant differences in the cumulative daily afterdischarge duration were observed between both groups. These findings suggest that preemptive LFS can significantly decrease the incidence of hippocampus-kindled seizures and delay the progression and secondary generalization of focal seizures.
文摘Effects of rolled leaf gene Rl（t） on grain quality characters of hybrid rice were analyzed by using three pairs of rolled leaf near-isogenic lines under two fertilizer treatments. Under normal fertilizer level （e.g. 450 kg urea per ha）, head rice rates and milled rice recovery of rolled leaf hybrids were significantly higher than those of corresponding non-rolled crosses, while the chalky rice rate and chalkiness were all lower. Of the RVA profiles, the peak viscosity, the hot paste viscosity and the breakdown viscosity of the rolled were all higher than those of the corresponding non-rolled ones to various degrees. Increasing fertilizer application for promoting panicle development increased the brown, milled and head rice rates except for Shanyou 63, furthermore, significant difference of head rice rates existed between the rolled leaf Shanyou 559 and Shanyou 559; while the peak viscosity, the hot paste viscosity and the breakdown viscosity all decreased to different levels; changes of values of other characters had no apparent regularity. It suggested that Rl（t） could improve rice quality under certain conditions.
文摘目的探讨快速康复方案在继发性甲状旁腺功能亢进患者中的应用效果。方法选取2020年1月至2023年6月于河北医科大学第三医院行甲状旁腺切除术治疗的200例继发性甲状旁腺功能亢进患者为研究对象,按照随机数字表法将其分为观察组与对照组,各100例。观察组给予快速康复策略,对照组给予常规护理。比较两组手术时间、住院时间、术后卧床时间、住院费用。比较两组不同时间点C反应蛋白(CRP)、白细胞介素-1(IL-1)、转化生长因子-β_(1)(TGF-β_(1))、血钙、视觉模拟评分法(VAS)评分、医学研究理事会评估表(MRC)评分、体重指数。结果两组手术时间比较,差异无统计学意义(P>0.05);观察组住院时间、术后卧床时间短于对照组,住院费用低于对照组,差异有统计学意义(P<0.05)。两组术后1、3、5 d CRP、IL-1、TGF-β_(1)水平均高于术前,术后3、5 d CRP、IL-1、TGF-β_(1)水平低于术1 d,术后5 d CRP、IL-1、TGF-β_(1)水平低于术后3 d,差异有统计学意义(P<0.05);观察组术后3、5 d CRP、IL-1、TGF-β_(1)水平均低于对照组,差异有统计学意义(P<0.05)。两组术后1、3、5 d血钙水平均低于术前,差异有统计学意义(P<0.05);观察组术后1、3、5 d血钙水平均高于对照组,差异有统计学意义(P<0.05)。两组术后3、5 d VAS评分均低于术后1 d(P<0.05);观察组术后1、3、5 d VAS评分低于对照组,差异有统计学意义(P<0.05)。术前与术后,两组MRC评分、体重指数比较,差异无统计学意义(P>0.05)。观察组总并发症发生率低于对照组,差异有统计学意义(P<0.05)。结论快速康复策略在继发性甲状旁腺功能亢进患者中有利于控制炎症和降低并发症发生率,对促进早期康复具有重要意义。
文摘In this paper, the unsteady effect of airflow is introduced into the calculation of aircraft maneuver load, and the results are compared with those obtained by quasi-steady method. Taking the steep pitch maneuver of an aircraft as an example, two methods are used to calculate the aircraft response after the rudder input is given according to the specifications. The calculation results show that if the peak overload of the aircraft is the same, the horizontal tail load increases by about 1% when the unsteady effect of the airflow is taken into account. If the rudder input of the two methods is the same, the unsteady calculation method will increase more. At the same time, the calculation shows that the bigger the deflection speed of rudder surface is, the bigger the difference between them is. Therefore, in order to improve the design quality of aircraft, it is necessary to introduce the unsteady effect into the calculation of loads in the detailed design stage of aircraft.
文摘Foil powders of Al 5.0 Cr 4.0 Y 1.5 Zr (%) were prepared by using a multi stage atomization rapid solidification powder making device. The obtained powders were exposed thermally at various temperatures. Variation of microstructures and properties of the alloy powders was investigated by micro hardness measurement, X ray diffraction, differential thermal analysis, and transmission electron microscopy with energy disperse X ray analyses. The results show that cubic Al 20 Cr 2Y ( a = 1.437?nm) and metastable Ll 2 Al 3Zr (FCC, a = 0.405?1?nm) or equilibrium DO 23 Al 3Zr (tetragonal structure, a = 0.409?1?nm, b = 1.73?0?nm) are main second phases precipitated from supersaturated solid solution of the rapidly solidified foil powders during thermal exposure. The cubic dispersion precipitates prior to the two other Al 3Zr type intermetallic phases in the course of the decomposition. Precipitation of incoherent Al 20 Cr 2Y results in softening of foil powder, and coherent Ll 2 Al 3Zr has intensive precipitation strengthening effect. The Al 20 Cr 2Y phase is structurally stable, but it is prone to coarsen and polygonize above 450?℃. Both Al 3Zr type intermetallic phases have much smaller coarsening rate than Al 20 Cr 2Y at temperature higher than 450?℃. These two phases are able to keep their fine spherical morphologies up to 550?℃, but Al 3Zr transforms into DO 23 structure from Ll 2 structure during thermal exposure above 550?℃.
