目的探讨分娩潜伏期行硬膜外镇痛对产妇和新生儿的影响。方法将开封市妇产医院2015年12月至2017年1月自然临产并接受分娩镇痛的240例初产妇分为观察组和对照组,每组120例。观察组产妇在分娩潜伏期开始行硬膜外自控分娩镇痛(PCEA),对照...目的探讨分娩潜伏期行硬膜外镇痛对产妇和新生儿的影响。方法将开封市妇产医院2015年12月至2017年1月自然临产并接受分娩镇痛的240例初产妇分为观察组和对照组,每组120例。观察组产妇在分娩潜伏期开始行硬膜外自控分娩镇痛(PCEA),对照组产妇在分娩活跃期开始行PCEA,2组产妇均在麻醉穿刺成功后给予甲磺酸罗哌卡因、枸橼酸舒芬太尼混合液10~15 m L注入硬膜外腔,然后采用自控镇痛泵行PCEA。观察2组产妇的第1产程时间(T1)、第2产程时间(T2)和视觉模拟法(VAS)评分、中转剖宫产及镇痛满意情况,并比较2组产妇镇痛期间血压、心率及新生儿Apgar评分、窒息率。结果观察组产妇T1、T2显著短于对照组(P<0.05),VAS评分显著低于对照组(P<0.05)。2组产妇镇痛期间血压和心率比较差异无统计学意义(P>0.05)。对照组产妇中转剖宫产率、镇痛满意率分别为10.83%、70.83%,观察组产妇中转剖宫产率、镇痛满意率分别为3.33%、95.83%,观察组产妇中转剖宫产率显著低于对照组(χ~2=5.128,P<0.05),镇痛满意率显著高于对照组(χ~2=27.000,P<0.05)。2组新生儿Apgar评分比较差异无统计学意义(P>0.05)。对照组和观察组新生儿窒息率分别为3.0%和2.5%,2组新生儿窒息率比较差异无统计学意义(χ~2=0.147,P>0.05)。结论产妇在分娩潜伏期行硬膜外镇痛效果满意,并可缩短产程,降低剖宫产率,且不增加母婴风险。展开更多
A dispersion system fluid can convect even if the dispersoid is a solid phase.Therefore,heat exchange performance can be improved while maintaining fluidity using a material with high thermal conductivity as the dispe...A dispersion system fluid can convect even if the dispersoid is a solid phase.Therefore,heat exchange performance can be improved while maintaining fluidity using a material with high thermal conductivity as the dispersoid.This study presents the melting performance evaluation results of a latent heat storage material with a carbon nanotube(CNT)dispersion system with high thermal conductivity,which enhances the thermal conductivity of the latent heat storage material and does not limit free convection.Increasing the thermal conductivity and enhancing the melting convection of the heat storage material result in increased latent heat storage speed.In this study,the thermal conductivity of the latent heat storage material was successfully increased by dispersing CNTs in the material.When 0.1%(in mass)of multi-wall CNT(MWCNT)was dispersed in a paraffin-based latent heat storage material,the shear stress increased by 1.5 times at a shear rate of 500 s^(-1),while taking into account the potential effects of convective inhibition.Therefore,a latent heat storage experiment was conducted in a rectangular heat storage tank using the CNT dispersion composition ratio as a parameter.A rectangular vessel with a heated vertical surface was used for the latent heat storage experiment.The melting speed was determined by comparing the amount of latent heat stored in a CNT-dispersed latent heat storage material and a single-phase latent heat storage material sample.The experimental results show that the time required for the latent heat storage material to completely melt in the heat storage tank was the shortest for the single-phase latent heat storage material sample.However,the fastest melting progress was observed for the sample with 0.02%(in mass)MWCNT content in the melting rate range of up to approximately 40%in the tank.The results indicate that this phenomenon is caused by the difference in the melting rates in the upper part of the tank.The generated data are useful for determining the shape and heat transfer surface arr展开更多
The melting process of solid-liquid phase change materials(PCM)has a significant impact on their energy storage performance.To more effectively apply solid-liquid PCM for energy storage,it is crucial to study the regu...The melting process of solid-liquid phase change materials(PCM)has a significant impact on their energy storage performance.To more effectively apply solid-liquid PCM for energy storage,it is crucial to study the regulation of melting process of solid-liquid PCM,which is numerically investigated based on double multiple relaxation time lattice Boltzmann method(MRT-LBM)in this work.In this work we pay more attention to the effects of different Stefan numbers(Ste)and Rayleigh numbers(Ra)on the melting process.The results indicate that the PCM melting is greatly influenced by the Ste number and Ra number,which can be divided into the heat conduction dominant stage and the convection dominant stage,according to the onset time of convection Fo_(C).In order to describe the contribution of the heat conduction dominant stage to the whole melting process quantitatively,we firstly propose the ratio of the heat conduction dominant stage R_(pc),which can be defined as the ratio of Fo_(C)to the complete melting time Fo_(M).R_(pc)gradually decreases as the Ra number increases,and when the Ste number rises:R_(pc)=90.0%when Ste=1.0 and Ra=1×10^(5),R_(pc)=39.6%when Ste=0.1 and Ra=1×10^(5),and R_(pc)=14.0%when Ste=1.0 and Ra=1×10~7.A regime map about the effects of different Ste numbers and Ra numbers on R_(pc)has been further summarized.The discovered findings would be helpful in regulating melting process in the energy storage of solid-liquid PCM.展开更多
文摘目的探讨分娩潜伏期行硬膜外镇痛对产妇和新生儿的影响。方法将开封市妇产医院2015年12月至2017年1月自然临产并接受分娩镇痛的240例初产妇分为观察组和对照组,每组120例。观察组产妇在分娩潜伏期开始行硬膜外自控分娩镇痛(PCEA),对照组产妇在分娩活跃期开始行PCEA,2组产妇均在麻醉穿刺成功后给予甲磺酸罗哌卡因、枸橼酸舒芬太尼混合液10~15 m L注入硬膜外腔,然后采用自控镇痛泵行PCEA。观察2组产妇的第1产程时间(T1)、第2产程时间(T2)和视觉模拟法(VAS)评分、中转剖宫产及镇痛满意情况,并比较2组产妇镇痛期间血压、心率及新生儿Apgar评分、窒息率。结果观察组产妇T1、T2显著短于对照组(P<0.05),VAS评分显著低于对照组(P<0.05)。2组产妇镇痛期间血压和心率比较差异无统计学意义(P>0.05)。对照组产妇中转剖宫产率、镇痛满意率分别为10.83%、70.83%,观察组产妇中转剖宫产率、镇痛满意率分别为3.33%、95.83%,观察组产妇中转剖宫产率显著低于对照组(χ~2=5.128,P<0.05),镇痛满意率显著高于对照组(χ~2=27.000,P<0.05)。2组新生儿Apgar评分比较差异无统计学意义(P>0.05)。对照组和观察组新生儿窒息率分别为3.0%和2.5%,2组新生儿窒息率比较差异无统计学意义(χ~2=0.147,P>0.05)。结论产妇在分娩潜伏期行硬膜外镇痛效果满意,并可缩短产程,降低剖宫产率,且不增加母婴风险。
基金supported by JSPS KAKENHI(Grant numbers JP18K03999 and 22K03958)。
文摘A dispersion system fluid can convect even if the dispersoid is a solid phase.Therefore,heat exchange performance can be improved while maintaining fluidity using a material with high thermal conductivity as the dispersoid.This study presents the melting performance evaluation results of a latent heat storage material with a carbon nanotube(CNT)dispersion system with high thermal conductivity,which enhances the thermal conductivity of the latent heat storage material and does not limit free convection.Increasing the thermal conductivity and enhancing the melting convection of the heat storage material result in increased latent heat storage speed.In this study,the thermal conductivity of the latent heat storage material was successfully increased by dispersing CNTs in the material.When 0.1%(in mass)of multi-wall CNT(MWCNT)was dispersed in a paraffin-based latent heat storage material,the shear stress increased by 1.5 times at a shear rate of 500 s^(-1),while taking into account the potential effects of convective inhibition.Therefore,a latent heat storage experiment was conducted in a rectangular heat storage tank using the CNT dispersion composition ratio as a parameter.A rectangular vessel with a heated vertical surface was used for the latent heat storage experiment.The melting speed was determined by comparing the amount of latent heat stored in a CNT-dispersed latent heat storage material and a single-phase latent heat storage material sample.The experimental results show that the time required for the latent heat storage material to completely melt in the heat storage tank was the shortest for the single-phase latent heat storage material sample.However,the fastest melting progress was observed for the sample with 0.02%(in mass)MWCNT content in the melting rate range of up to approximately 40%in the tank.The results indicate that this phenomenon is caused by the difference in the melting rates in the upper part of the tank.The generated data are useful for determining the shape and heat transfer surface arr
基金financially supported by Natural Science Foundation of Heilongjiang Province(Grant No.ZD2021E002)。
文摘The melting process of solid-liquid phase change materials(PCM)has a significant impact on their energy storage performance.To more effectively apply solid-liquid PCM for energy storage,it is crucial to study the regulation of melting process of solid-liquid PCM,which is numerically investigated based on double multiple relaxation time lattice Boltzmann method(MRT-LBM)in this work.In this work we pay more attention to the effects of different Stefan numbers(Ste)and Rayleigh numbers(Ra)on the melting process.The results indicate that the PCM melting is greatly influenced by the Ste number and Ra number,which can be divided into the heat conduction dominant stage and the convection dominant stage,according to the onset time of convection Fo_(C).In order to describe the contribution of the heat conduction dominant stage to the whole melting process quantitatively,we firstly propose the ratio of the heat conduction dominant stage R_(pc),which can be defined as the ratio of Fo_(C)to the complete melting time Fo_(M).R_(pc)gradually decreases as the Ra number increases,and when the Ste number rises:R_(pc)=90.0%when Ste=1.0 and Ra=1×10^(5),R_(pc)=39.6%when Ste=0.1 and Ra=1×10^(5),and R_(pc)=14.0%when Ste=1.0 and Ra=1×10~7.A regime map about the effects of different Ste numbers and Ra numbers on R_(pc)has been further summarized.The discovered findings would be helpful in regulating melting process in the energy storage of solid-liquid PCM.
