Herein,a physical and mathematical model of the voltage−current characteristics of a p−n heterostructure with quantum wells(QWs)is prepared using the Sah−Noyce−Shockley(SNS)recombination mechanism to show the SNS recombination rate of the correction function of the distribution of QWs in the space charge region of diode configuration.A comparison of the model voltage−current characteristics(VCCs)with the experimental ones reveals their adequacy.The technological parameters of the structure of the VCC model are determined experimentally using a nondestructive capacitive approach for determining the impurity distribution profile in the active region of the diode structure with a profile depth resolution of up to 10Å.The correction function in the expression of the recombination rate shows the possibility of determining the derivative of the VCCs of structures with QWs with a nonideality factor of up to 4.
A novel design of Return Flow Solar Air Heater(RFSAH)with different arrangements of baffles especially V-Type Artificial roughness is simulated and numerically analyzed with energy balance equations.To enhance the effectiveness of baffles,numerous studies have been conducted.The performance of the RFSAH is studied in terms of thermal efficiency,thermo-hydraulic efficiency,and optimization of baffle parameters.Maximum Thermal efficiency and thermo-hydraulic efficiency are found in RFSAH with baffle on both sides of the absorber plate and mass flow rate above 0.2kg/s.Sensitivity analysis of the influencing parameters is carried out and reported the best performance of the system on selective geometrical parameters(ψ=0.7,β=20%,e/H=1,p/e=0.8,α=60°).The results obtained from the present model are validated with the published experimental results and have been found in quite reasonable agreement with an average error of 16.45%.Thermal and Thermohydraulic efficiency of RFSAH with a baffle on both sides of the absorber plate is maximum among baffles below,above,and on both sides of the absorber plate.It is observed that the thermal efficiency of RFSAH is greater than SF-SAH.The proposed optimum baffles roughness is suggested to increase the air upholding time period for more efficient output.
目的探究CXC趋化因子受体2(CXC chemokine receptor 2,CXCR2)、紧密连接蛋白1(zonula occluden-1,ZO-1)在颅内动脉瘤破裂蛛网膜下腔出血(subarachnoid hemorrhage,SAH)患者术后脑血管痉挛中的预测价值。方法选择2020年5月至2023年10月开封市中心医院神经内科一病区收治的颅内动脉瘤破裂SAH患者215例。根据术后脑血管痉挛情况分为痉挛组70例和未痉挛组145例。痉挛组根据严重程度分为重度组18例,中度组38例,轻度组14例。采用酶联免疫吸附法检测患者血清CXCR2、ZO-1水平,采用Spearman、Pearson相关性分析,多因素logistic回归分析,ROC曲线分析检验相关性、影响因素和指标的预测价值,并计算曲线下面积(area under curve,AUC)。结果痉挛组CXCR2、ZO-1、颅内出血、入院格拉斯哥昏迷(Glasgow coma scale,GCS)评分3~8分、Hunt-Hess分级Ⅲ级、Fisher分级Ⅲ级和Ⅳ级比例显著高于未痉挛组,差异有统计学意义(P<0.01)。颅内动脉瘤破裂SAH患者颅内出血、Hunt-Hess分级、Fisher分级与CXCR2、ZO-1水平呈正相关,入院GCS评分与CXCR2、ZO-1水平呈负相关(P<0.01)。CXCR2、ZO-1是颅内动脉瘤破裂SAH患者术后脑血管痉挛的独立危险因素(P<0.01)。CXCR2、ZO-1预测颅内动脉瘤破裂SAH患者术后脑血管痉挛的AUC分别为0.839(95%CI:0.780~0.898)、0.813(95%CI:0.750~0.876),二者联合预测颅内动脉瘤破裂SAH患者术后脑血管痉挛的AUC为0.910(95%CI:0.869~0.951),显著优于单独预测(Z=2.391、Z=3.266,P<0.05)。重度组、中度组和轻度组血清CXCR2、ZO-1水平依次升高,3组比较,差异有统计学意义(P<0.01)。结论血清CXCR2、ZO-1水平与颅内动脉瘤破裂SAH患者术后脑血管痉挛有关,可作为预后预测的潜在生物标志物。
