Several studies on functionally graded materials(FGMs)have been done by researchers,but few studies have dealt with the impact of the modification of the properties of materials with regard to the functional propagati...Several studies on functionally graded materials(FGMs)have been done by researchers,but few studies have dealt with the impact of the modification of the properties of materials with regard to the functional propagation of the waves in plates.This work aims to explore the effects of changing compositional characteristics and the volume fraction of the constituent of plate materials regarding the wave propagation response of thick plates of FGM.This model is based on a higher-order theory and a new displacement field with four unknowns that introduce indeterminate integral variables with a hyperbolic arcsine function.The FGM plate is assumed to consist of a mixture of metal and ceramic,and its properties change depending on the power functions of the thickness of the plate,such as linear,quadratic,cubic,and inverse quadratic.By utilizing Hamilton’s principle,general formulae of the wave propagation were obtained to establish wave modes and phase velocity curves of the wave propagation in a functionally graded plate,including the effects of changing compositional characteristics of materials.展开更多
Objective：To investigate the influences of urapidil and nicardipine on rabbit sinus function, atrio-ventricular node function and hemodynamics. Methods：Thirty-two Angora＇ s rabbits were selected and randomly divide...Objective：To investigate the influences of urapidil and nicardipine on rabbit sinus function, atrio-ventricular node function and hemodynamics. Methods：Thirty-two Angora＇ s rabbits were selected and randomly divided into four groups. U1 group：urapidil 0.25 mg/kg; U2 group：urapidil 0.5 mg/kg; N1 group：nicardipine 10 μg/kg; N2 group： nicardipine 20 μg/kg. All these medicine were administrated within 30 seconds. Measurements were taken before and after the administration of urapidil or nicardipine for the following data： mean blood pressure（MAP）, heart rate（HR）, sino-atrial conduction time（SACT）, maximal sinoatrial recovery time（SNRTmax） corrected sinus node recovery time（CSNRT）, index of sinus node recovery time（SNRTI）, Wenckebach A-V conduction frequency （WB）, and P-R interval. Results：Significant MAP and HR changes were identified in all of the four groups before and after administration of both urapidil and nicardipine. No significant changes could be found in the rest of the parameters. Intergroup analysis showed that SACT and CSNRT of N1 and N2 groups were shorter than those of the U2 group（P 〈 0.01）; the MAP decreased（P 〈 0.01） and the HR increased drastically（P〈 0.01）. Conclusions：Neither urapidil（0.25 mg/kg, 0,5 mg/kg） nor nicardipine（10 μg/kg, 20 μg/kg） has any significant influence on rabbit sinus function or rabbit atrio-ventricular node function. Nicardipine could be a better choice than urapidil for parafunctional sinus node patients.展开更多
文摘Several studies on functionally graded materials(FGMs)have been done by researchers,but few studies have dealt with the impact of the modification of the properties of materials with regard to the functional propagation of the waves in plates.This work aims to explore the effects of changing compositional characteristics and the volume fraction of the constituent of plate materials regarding the wave propagation response of thick plates of FGM.This model is based on a higher-order theory and a new displacement field with four unknowns that introduce indeterminate integral variables with a hyperbolic arcsine function.The FGM plate is assumed to consist of a mixture of metal and ceramic,and its properties change depending on the power functions of the thickness of the plate,such as linear,quadratic,cubic,and inverse quadratic.By utilizing Hamilton’s principle,general formulae of the wave propagation were obtained to establish wave modes and phase velocity curves of the wave propagation in a functionally graded plate,including the effects of changing compositional characteristics of materials.
文摘Objective：To investigate the influences of urapidil and nicardipine on rabbit sinus function, atrio-ventricular node function and hemodynamics. Methods：Thirty-two Angora＇ s rabbits were selected and randomly divided into four groups. U1 group：urapidil 0.25 mg/kg; U2 group：urapidil 0.5 mg/kg; N1 group：nicardipine 10 μg/kg; N2 group： nicardipine 20 μg/kg. All these medicine were administrated within 30 seconds. Measurements were taken before and after the administration of urapidil or nicardipine for the following data： mean blood pressure（MAP）, heart rate（HR）, sino-atrial conduction time（SACT）, maximal sinoatrial recovery time（SNRTmax） corrected sinus node recovery time（CSNRT）, index of sinus node recovery time（SNRTI）, Wenckebach A-V conduction frequency （WB）, and P-R interval. Results：Significant MAP and HR changes were identified in all of the four groups before and after administration of both urapidil and nicardipine. No significant changes could be found in the rest of the parameters. Intergroup analysis showed that SACT and CSNRT of N1 and N2 groups were shorter than those of the U2 group（P 〈 0.01）; the MAP decreased（P 〈 0.01） and the HR increased drastically（P〈 0.01）. Conclusions：Neither urapidil（0.25 mg/kg, 0,5 mg/kg） nor nicardipine（10 μg/kg, 20 μg/kg） has any significant influence on rabbit sinus function or rabbit atrio-ventricular node function. Nicardipine could be a better choice than urapidil for parafunctional sinus node patients.
