利用植物蛋白酶-醇析法对柠檬皮果胶的提取工艺进行研究。考察液料比、缓冲液pH、提取时间、提取温度、酶浓度对果胶得率的影响,采用单因素试验及正交试验得到柠檬皮果胶的最佳提取工艺条件:提取时间50 min,温度54℃,p H 7.0,加酶量3 mg...利用植物蛋白酶-醇析法对柠檬皮果胶的提取工艺进行研究。考察液料比、缓冲液pH、提取时间、提取温度、酶浓度对果胶得率的影响,采用单因素试验及正交试验得到柠檬皮果胶的最佳提取工艺条件:提取时间50 min,温度54℃,p H 7.0,加酶量3 mg/g,液料比20∶1。在此条件下进行了3次平行试验,在平行实验中其重现性很好,结果表明此工艺条件确实是稳定性良好的最佳工艺条件,果胶平均得率为27.60%。展开更多
大气边界层(ABL)中标量的仿真对于掌握大气中温度、湿度等的分布,污染物的扩散规律及预测雨水的生成等均具有重要意义。大涡模拟(LES)是当前ABL湍流仿真的主要方法,其关键是如何利用解析尺度的速度场和标量场信息构建亚网格(SGS)应力模...大气边界层(ABL)中标量的仿真对于掌握大气中温度、湿度等的分布,污染物的扩散规律及预测雨水的生成等均具有重要意义。大涡模拟(LES)是当前ABL湍流仿真的主要方法,其关键是如何利用解析尺度的速度场和标量场信息构建亚网格(SGS)应力模型和通量模型。对于ABL湍流这一典型的高雷诺数条件下的非各向同性湍流,以Boussinesq假设为出发点构建的粘性SGS模型存在先验误差较大、后验耗散过强等许多问题。本研究引入一种新的非线性SGS通量模型,该模拟不预先假设能量的传输方向,基于速度和标量的梯度计算SGS通量的结构(矢量分量的相对大小),且摈弃局部平衡假设,采用动力学方程考虑能量反传,预测SGS通量强度的动态演化过程。研究采用一个中性ABL基准工况,通过与已有的理论预测和各种流动统计的对比进行系统的考察来对模型进行评估,同时也与传统粘性SGS模型的表现进行比较。具体地,当LES达到统计稳定后,我们重点关注了在不同网格条件下模型对无量纲速度梯度、无量纲标量梯度、能谱及流场结构等的预测结果。结果表明,除了可以获取可靠的流场结构,相比传统粘性SGS模型,新模型对无量纲梯度预测的准确度有明显提升,且对湍流能谱的预测有显著改善。此外,我们讨论了新模型预测效果提升的原因,相较于传统粘性SGS模型存在耗散较强的问题,新模型采用动态非线性的建模方法,可以预测ABL湍流中能量的逆向输运,并更好地捕捉小尺度的涡旋。The simulation of scalars in the atmospheric boundary layer (ABL) is of great significance for understanding the distribution of temperature, humidity, and other factors in the atmosphere, as well as the diffusion patterns of pollutants and the prediction of rain generation. Large-Eddy Simulation (LES) is currently the main method for ABL turbulence simulation, and the key is how to construct sub-grid-scale (SGS) stress model and flux model by using the velocity and scalar field information of analytic scale. For ABL turbulence, a typical non-isotropic turbulence under high Reynolds number conditions, the viscous SGS model based on the Boussinesq hypothesis has many problems, such as large prior errors and strong posterior dissipation. This study introduces a new nonlinear SGS flux model, which simulates the structure of SGS flux (relative magnitude of vector components) based on velocity and scalar gradients without assuming the direction of energy transfer. In addition, the local equilibrium hypothesis is discarded, and kinetic equations are adopted to consider the reverse energy transfer and predict the dynamic evolution of SGS flux intensity. The study used a neutral ABL benchmark operating condition and systematically evaluated the model by comparing it with existing theoretical predictions and various flow statistics, as well as comparing its performance with traditional viscous SGS models. Specifically, when LES reaches statistical stability, we focus on the prediction results of the model for dimensionless velocity gradient, dimensionless scalar gradient, energy spectrum, and flow field structure under different grid conditions. The results show that in addition to obtaining reliable flow field structure, compared with the traditional viscous SGS model, the new model significantly improves the accuracy of dimensionless gradient prediction and turbulence energy spectrum prediction. In addition, we discussed the reasons for the improved prediction performance of the new model. Compared with the traditional viscous SGS model, which has a strong dissipation problem, the new model adopts a dynamic nonlinear modeling method, which can predict the reverse energy transport in ABL turbulence and better capture small-scale vortices.展开更多
目的通过Meta分析评价网络正念对癌症患者的干预效果。方法计算机检索中国知网(CNKI)、万方数据库、维普(VIP)、中国生物医学文献数据库(CBM)、Cochrane Library、PubMed、Web of Science、Embase、Scopus、Ovid内与癌症患者的网络正念...目的通过Meta分析评价网络正念对癌症患者的干预效果。方法计算机检索中国知网(CNKI)、万方数据库、维普(VIP)、中国生物医学文献数据库(CBM)、Cochrane Library、PubMed、Web of Science、Embase、Scopus、Ovid内与癌症患者的网络正念干预有关的文献,检索时间范围为建库至2022年7月,限定研究类型为随机对照试验。由2名研究人员进行质量评价,采用RevMan 5.4软件进行Meta分析。结果共纳入12篇文献,共涉及1292例患者,Meta分析结果显示:与常规护理措施相比较,网络正念干预能有效降低癌症患者的压力[SMD=-1.82,95%CI(-3.17,-0.47),P=0.008]、焦虑[SMD=-0.60,95%CI(-1.08,-0.12),P=0.01]、抑郁[SMD=-0.54,95%CI(-0.89,-0.18),P=0.003]水平,提高癌症患者的生活质量[SMD=1.55,95%CI(0.49,2.62),P=0.004],减轻癌症患者的睡眠障碍[SMD=-0.67,95%CI(-1.30,-0.03),P=0.04]、癌因性疲乏[SMD=-0.58,95%CI(-0.83,-0.33),P<0.00001]和癌症复发恐惧[MD=-2.44,95%CI(-4.51,-0.37),P=0.02]。结论网络正念干预能够有效降低癌症患者的压力、焦虑和抑郁水平,提高癌症患者的生活质量和睡眠质量,减轻患者的癌因性疲乏及癌症复发恐惧。受纳入文献的质量和数量限制,此结论需要开展更多的高质量研究加以验证。展开更多
文摘利用植物蛋白酶-醇析法对柠檬皮果胶的提取工艺进行研究。考察液料比、缓冲液pH、提取时间、提取温度、酶浓度对果胶得率的影响,采用单因素试验及正交试验得到柠檬皮果胶的最佳提取工艺条件:提取时间50 min,温度54℃,p H 7.0,加酶量3 mg/g,液料比20∶1。在此条件下进行了3次平行试验,在平行实验中其重现性很好,结果表明此工艺条件确实是稳定性良好的最佳工艺条件,果胶平均得率为27.60%。
文摘大气边界层(ABL)中标量的仿真对于掌握大气中温度、湿度等的分布,污染物的扩散规律及预测雨水的生成等均具有重要意义。大涡模拟(LES)是当前ABL湍流仿真的主要方法,其关键是如何利用解析尺度的速度场和标量场信息构建亚网格(SGS)应力模型和通量模型。对于ABL湍流这一典型的高雷诺数条件下的非各向同性湍流,以Boussinesq假设为出发点构建的粘性SGS模型存在先验误差较大、后验耗散过强等许多问题。本研究引入一种新的非线性SGS通量模型,该模拟不预先假设能量的传输方向,基于速度和标量的梯度计算SGS通量的结构(矢量分量的相对大小),且摈弃局部平衡假设,采用动力学方程考虑能量反传,预测SGS通量强度的动态演化过程。研究采用一个中性ABL基准工况,通过与已有的理论预测和各种流动统计的对比进行系统的考察来对模型进行评估,同时也与传统粘性SGS模型的表现进行比较。具体地,当LES达到统计稳定后,我们重点关注了在不同网格条件下模型对无量纲速度梯度、无量纲标量梯度、能谱及流场结构等的预测结果。结果表明,除了可以获取可靠的流场结构,相比传统粘性SGS模型,新模型对无量纲梯度预测的准确度有明显提升,且对湍流能谱的预测有显著改善。此外,我们讨论了新模型预测效果提升的原因,相较于传统粘性SGS模型存在耗散较强的问题,新模型采用动态非线性的建模方法,可以预测ABL湍流中能量的逆向输运,并更好地捕捉小尺度的涡旋。The simulation of scalars in the atmospheric boundary layer (ABL) is of great significance for understanding the distribution of temperature, humidity, and other factors in the atmosphere, as well as the diffusion patterns of pollutants and the prediction of rain generation. Large-Eddy Simulation (LES) is currently the main method for ABL turbulence simulation, and the key is how to construct sub-grid-scale (SGS) stress model and flux model by using the velocity and scalar field information of analytic scale. For ABL turbulence, a typical non-isotropic turbulence under high Reynolds number conditions, the viscous SGS model based on the Boussinesq hypothesis has many problems, such as large prior errors and strong posterior dissipation. This study introduces a new nonlinear SGS flux model, which simulates the structure of SGS flux (relative magnitude of vector components) based on velocity and scalar gradients without assuming the direction of energy transfer. In addition, the local equilibrium hypothesis is discarded, and kinetic equations are adopted to consider the reverse energy transfer and predict the dynamic evolution of SGS flux intensity. The study used a neutral ABL benchmark operating condition and systematically evaluated the model by comparing it with existing theoretical predictions and various flow statistics, as well as comparing its performance with traditional viscous SGS models. Specifically, when LES reaches statistical stability, we focus on the prediction results of the model for dimensionless velocity gradient, dimensionless scalar gradient, energy spectrum, and flow field structure under different grid conditions. The results show that in addition to obtaining reliable flow field structure, compared with the traditional viscous SGS model, the new model significantly improves the accuracy of dimensionless gradient prediction and turbulence energy spectrum prediction. In addition, we discussed the reasons for the improved prediction performance of the new model. Compared with the traditional viscous SGS model, which has a strong dissipation problem, the new model adopts a dynamic nonlinear modeling method, which can predict the reverse energy transport in ABL turbulence and better capture small-scale vortices.
文摘目的通过Meta分析评价网络正念对癌症患者的干预效果。方法计算机检索中国知网(CNKI)、万方数据库、维普(VIP)、中国生物医学文献数据库(CBM)、Cochrane Library、PubMed、Web of Science、Embase、Scopus、Ovid内与癌症患者的网络正念干预有关的文献,检索时间范围为建库至2022年7月,限定研究类型为随机对照试验。由2名研究人员进行质量评价,采用RevMan 5.4软件进行Meta分析。结果共纳入12篇文献,共涉及1292例患者,Meta分析结果显示:与常规护理措施相比较,网络正念干预能有效降低癌症患者的压力[SMD=-1.82,95%CI(-3.17,-0.47),P=0.008]、焦虑[SMD=-0.60,95%CI(-1.08,-0.12),P=0.01]、抑郁[SMD=-0.54,95%CI(-0.89,-0.18),P=0.003]水平,提高癌症患者的生活质量[SMD=1.55,95%CI(0.49,2.62),P=0.004],减轻癌症患者的睡眠障碍[SMD=-0.67,95%CI(-1.30,-0.03),P=0.04]、癌因性疲乏[SMD=-0.58,95%CI(-0.83,-0.33),P<0.00001]和癌症复发恐惧[MD=-2.44,95%CI(-4.51,-0.37),P=0.02]。结论网络正念干预能够有效降低癌症患者的压力、焦虑和抑郁水平,提高癌症患者的生活质量和睡眠质量,减轻患者的癌因性疲乏及癌症复发恐惧。受纳入文献的质量和数量限制,此结论需要开展更多的高质量研究加以验证。
