目的:探讨黄芪注射液对肠系膜上动脉闭塞性(superior mesenteric artery occlusion,SMAO)休克脂质过氧化损伤的防治作用及其机制.方法:经腹分离兔肠系膜上动脉并夹闭2h后松夹,复制SMAO休克动物模型,并于松夹前、后各15min分别将黄芪注射...目的:探讨黄芪注射液对肠系膜上动脉闭塞性(superior mesenteric artery occlusion,SMAO)休克脂质过氧化损伤的防治作用及其机制.方法:经腹分离兔肠系膜上动脉并夹闭2h后松夹,复制SMAO休克动物模型,并于松夹前、后各15min分别将黄芪注射液1mL/kg以2倍的NS配制自耳缘iv,观察动物血压、血浆及红细胞膜丙二醛(MDA)、红细胞膜微黏度、红细胞超氧化物歧化酶(SOD)、血浆黄嘌呤氧化酶(XOD)、乳酸脱氢酶(LDH)及酸性磷酸酶(ACP)含量的变化;并进行小肠组织病理学检查.结果:与对照组比较,SMAO组血压和红细胞SOD降低(均P<0.01),红细胞膜微粘度、红细胞膜MDA以及血浆MDA,XOD,LDH和ACP的水平明显升高(均P<0.01),光镜下小肠病理损害明显.黄芪注射液治疗后上述各指标均较SMAO组明显改善(80.1±3.6 vs 39.4±5.2,4.63±0.57 vs 3.44±0.61,3.35±0.34 vs 4.09±0.38,0.23±0.02 vs 0.41±0.02,3.61±0.41 vs 4.32±0.92,71.4±13.1 vs 92.5±13.9,50.2±18.2 vs 105.5±37.0,37.0±11.8 vs 71.7±22.0,均P<0.01).结论:SMAO休克伴有氧自由基代谢紊乱,体内脂质过氧化过程加强.黄芪注射液通过抗脂质过氧化稳定细胞膜,改善红细胞膜微黏度,减轻组织损伤,延缓SMAO休克的发展.展开更多
Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylid...Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride （PVDF, 0.1 μm）, cellulose acetate （CA, 0.22 μm）, sulfonated polyethersulfone （SPES, 0.22 μm） and polyamide （PA, 0.45 μm）, respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.展开更多
A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial direc...A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial direction.The size effect is incorporated by employing the modified couple stress theory and Kelvin-Voigt viscoelastic model,so that viscous components are included in the stress and the deviatoric segments of the symmetric couple stress tensors.The components of strain,curvature,stress and couple stress are formulated by combining them with the Timoshenko beam theory.Based on the Hamilton principle,the governing differential equations and boundary conditions for the micro-beam are expressed with arbitrary beam section shape and arbitrary type of loads.The size effect,FG effect,Poisson effect,and the influence of the beam section shape on the mechanical behaviors of viscoelastic FG micro-beams are investigated by taking the simply supported micro-beam subjected to point load as an example.Results show that the size effect on deflection,normal stress and couple stress are obvious when the size of the micro-beam is small enough,and the FG effects are obvious when the size of the micro-beam is large enough.Moreover,the Poisson ratio influences the size effect significantly and the beam section shape is also an important factor influencing the mechanical behavior of the micro-beam.展开更多
文摘目的:探讨黄芪注射液对肠系膜上动脉闭塞性(superior mesenteric artery occlusion,SMAO)休克脂质过氧化损伤的防治作用及其机制.方法:经腹分离兔肠系膜上动脉并夹闭2h后松夹,复制SMAO休克动物模型,并于松夹前、后各15min分别将黄芪注射液1mL/kg以2倍的NS配制自耳缘iv,观察动物血压、血浆及红细胞膜丙二醛(MDA)、红细胞膜微黏度、红细胞超氧化物歧化酶(SOD)、血浆黄嘌呤氧化酶(XOD)、乳酸脱氢酶(LDH)及酸性磷酸酶(ACP)含量的变化;并进行小肠组织病理学检查.结果:与对照组比较,SMAO组血压和红细胞SOD降低(均P<0.01),红细胞膜微粘度、红细胞膜MDA以及血浆MDA,XOD,LDH和ACP的水平明显升高(均P<0.01),光镜下小肠病理损害明显.黄芪注射液治疗后上述各指标均较SMAO组明显改善(80.1±3.6 vs 39.4±5.2,4.63±0.57 vs 3.44±0.61,3.35±0.34 vs 4.09±0.38,0.23±0.02 vs 0.41±0.02,3.61±0.41 vs 4.32±0.92,71.4±13.1 vs 92.5±13.9,50.2±18.2 vs 105.5±37.0,37.0±11.8 vs 71.7±22.0,均P<0.01).结论:SMAO休克伴有氧自由基代谢紊乱,体内脂质过氧化过程加强.黄芪注射液通过抗脂质过氧化稳定细胞膜,改善红细胞膜微黏度,减轻组织损伤,延缓SMAO休克的发展.
基金Supported by the State Key Development Program for Basic Research of China(2003CB615705)
文摘Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride （PVDF, 0.1 μm）, cellulose acetate （CA, 0.22 μm）, sulfonated polyethersulfone （SPES, 0.22 μm） and polyamide （PA, 0.45 μm）, respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.
基金The National Science and Technology Major Project(No.2017ZX05009-003)the National Key Research and Development Program of China(No.2017YFC0307604)the Talent Foundation of China University of Petroleum(No.Y1215042)。
文摘A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial direction.The size effect is incorporated by employing the modified couple stress theory and Kelvin-Voigt viscoelastic model,so that viscous components are included in the stress and the deviatoric segments of the symmetric couple stress tensors.The components of strain,curvature,stress and couple stress are formulated by combining them with the Timoshenko beam theory.Based on the Hamilton principle,the governing differential equations and boundary conditions for the micro-beam are expressed with arbitrary beam section shape and arbitrary type of loads.The size effect,FG effect,Poisson effect,and the influence of the beam section shape on the mechanical behaviors of viscoelastic FG micro-beams are investigated by taking the simply supported micro-beam subjected to point load as an example.Results show that the size effect on deflection,normal stress and couple stress are obvious when the size of the micro-beam is small enough,and the FG effects are obvious when the size of the micro-beam is large enough.Moreover,the Poisson ratio influences the size effect significantly and the beam section shape is also an important factor influencing the mechanical behavior of the micro-beam.
