Ceramic and polytetrafluoroethylene composites as dielectric materials have a low dielectric loss at high frequency and play an important role in the modern communication field.However,room temperature phase transform...Ceramic and polytetrafluoroethylene composites as dielectric materials have a low dielectric loss at high frequency and play an important role in the modern communication field.However,room temperature phase transformation of PTFE resins,which is accompanied by a large volume change(>400 ppm/℃),seriously affects the dimensional stability and performance stability of materials.The LD125 modified glass fiber(GF)was introduced to the CaO-Li2 O-Sm2O3-TiO2(CLST)/PTFE composite,to reduce the thermal expansion coefficient(CTE)of the composites.The tri-phase composites(CLST/PTFE/GF)show the low dielectric loss and excellent machine-ability.The effect of GF content on the dielectric properties and CTE was also investigated.The CLST/PTFE filled with 5%GF exhibits the best overall performance,which is a promising microwave dielectric material for microwave communication.展开更多
目的 探讨呼气末正压(PEEP)对右心室Tei指数的影响。方法 选择2021年6月至2022年1月收治的52例机械通气的危重症患者,使用容量控制的通气模式,分别设置PEEP为4、8和12 cm H_(2)O,比较改变PEEP后血氧饱和度、心率(HR)、平均动脉压(MAP)...目的 探讨呼气末正压(PEEP)对右心室Tei指数的影响。方法 选择2021年6月至2022年1月收治的52例机械通气的危重症患者,使用容量控制的通气模式,分别设置PEEP为4、8和12 cm H_(2)O,比较改变PEEP后血氧饱和度、心率(HR)、平均动脉压(MAP)、血乳酸及肺静态顺应性(Clst)的变化。对患者进行超声心动图检查,测量右心室心肌做功指数(Tei指数)、心输出量,进行前后对比。结果 纳入52例患者,PEEP为4、8和12 cm H_(2)O时,血氧饱和度、心率、平均动脉压及乳酸无明显变化;Clst分别为50.72(43.61,57.85)、45.60(42.21,51.22)及37.39(31.64,41.20),各组之间差异有统计学意义(P<0.05);Tei指数分别为0.41(0.31,0.46)、0.44(0.36,0.52)和0.57(0.49,0.72),各组之间差异有统计学意义(P<0.05)。然而,左心室心输出量未出现明显变化,分别为4.72(4.37,5.21)L/min,4.72(4.23,5.24)L/min和4.73(4.22,5.30)L/min,差异无统计学意义(P>0.05)。结论 适当增加PEEP可能导致肺部静态顺应性减小,同时右心室Tei指数升高,提示右心室负荷增大,但心输出量没有明显改变。展开更多
基金supported by the National Natural Science Foundation of China(No.51572205)the Equipment Pre-Research Joint Fund of EDD and MOE(No.6141A02033209)+1 种基金the Fundamental Research Funds for the Central Universities(WUT:Nos.2017III035,2018III019)the Natural Science Foundation of Hubei Province,China(No.2014CFB854)
文摘Ceramic and polytetrafluoroethylene composites as dielectric materials have a low dielectric loss at high frequency and play an important role in the modern communication field.However,room temperature phase transformation of PTFE resins,which is accompanied by a large volume change(>400 ppm/℃),seriously affects the dimensional stability and performance stability of materials.The LD125 modified glass fiber(GF)was introduced to the CaO-Li2 O-Sm2O3-TiO2(CLST)/PTFE composite,to reduce the thermal expansion coefficient(CTE)of the composites.The tri-phase composites(CLST/PTFE/GF)show the low dielectric loss and excellent machine-ability.The effect of GF content on the dielectric properties and CTE was also investigated.The CLST/PTFE filled with 5%GF exhibits the best overall performance,which is a promising microwave dielectric material for microwave communication.
文摘目的 探讨呼气末正压(PEEP)对右心室Tei指数的影响。方法 选择2021年6月至2022年1月收治的52例机械通气的危重症患者,使用容量控制的通气模式,分别设置PEEP为4、8和12 cm H_(2)O,比较改变PEEP后血氧饱和度、心率(HR)、平均动脉压(MAP)、血乳酸及肺静态顺应性(Clst)的变化。对患者进行超声心动图检查,测量右心室心肌做功指数(Tei指数)、心输出量,进行前后对比。结果 纳入52例患者,PEEP为4、8和12 cm H_(2)O时,血氧饱和度、心率、平均动脉压及乳酸无明显变化;Clst分别为50.72(43.61,57.85)、45.60(42.21,51.22)及37.39(31.64,41.20),各组之间差异有统计学意义(P<0.05);Tei指数分别为0.41(0.31,0.46)、0.44(0.36,0.52)和0.57(0.49,0.72),各组之间差异有统计学意义(P<0.05)。然而,左心室心输出量未出现明显变化,分别为4.72(4.37,5.21)L/min,4.72(4.23,5.24)L/min和4.73(4.22,5.30)L/min,差异无统计学意义(P>0.05)。结论 适当增加PEEP可能导致肺部静态顺应性减小,同时右心室Tei指数升高,提示右心室负荷增大,但心输出量没有明显改变。
