With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others w...With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others without the protection of face masks,which greatly increases the risk of COVID-19 transmission.Therefore,the transmission mechanism of respiratory droplets in extremely crowded dining environments should be investigated.In this study,a numerical simulation of coughing at dining tables under two conditions was performed,namely the presence and absence of protective partitions,and the evaporation and condensation of aerosol droplets in the air were examined.By using the numerical method,we analyzed and verified the isolation effect of dining table partitions in the propagation of aerosol droplets.The effect of changes in room temperature on the diffusion of coughed aerosols when partitions were present was analyzed.We demonstrated how respiratory droplets spread through coughing and how these droplets affect others.Finally,we proposed a design for a dining table partition that minimizes the transmission of COVID-19.展开更多
The superplastic deformation behavior of SiCw/ZK60 composite was investigated at temperatures ranging from 573K to 723K and at initial strain rates ranging from 8.3x10-4s-1 to 8.3x10-2s-1. A maximum elongation of 200%...The superplastic deformation behavior of SiCw/ZK60 composite was investigated at temperatures ranging from 573K to 723K and at initial strain rates ranging from 8.3x10-4s-1 to 8.3x10-2s-1. A maximum elongation of 200% with a m-value of 0.35 was obtained at 613K and a initial strain rate of 1.67x 10-2s-1. The apparent activation energy (98kJ/mol) approximates that for grain boundary diffusion (92kJ/mol) in magnesium. It is proposed that the dominant mechanism of superplastic deformation in the present composite is grain boundary sliding accommodated by diffusional transport, besides, interfacial sliding plays an important role in the superplastic deformation.展开更多
Phenolic compounds are major bioactive chemicals in plant-based food products with proven health benefits.However,alkaline pH processing promotes phenolic compounds auto-oxidation,leading to a loss in food products an...Phenolic compounds are major bioactive chemicals in plant-based food products with proven health benefits.However,alkaline pH processing promotes phenolic compounds auto-oxidation,leading to a loss in food products and by-products.A phenolic-rich brewery effluent,representative of plant-based food matrices,was subdued to aging tests to investigate phenolic compounds stability in different conditions.Three conditions were tested:pH 2 in atmospheric air,pH 13.5 in atmospheric air and under N2 flow.Studied phenolic compounds remained stable in acid pH and alkaline pH under N2 but decreased sharply in alkaline pH.Interestingly,global antioxidant capacity was either stable or degraded according to antioxidant assay performed.Phenolic compounds and their corresponding antioxidant capacity study with coupled HPLC-antioxidant capacity showed that their chemical structure drove their stability.Flavan-3-ols were the main compounds prone to auto-oxidation,followed by catechol acids.Monohydroxy phenolic acids were resistant to major auto-oxidation.This study highlights food phenolic compounds behavior with consequences on antioxidant capacity in a real agro-food system in extreme alkaline condition.展开更多
基金the National Natural Science Foundation of China(11872353,91852102)the Natural Science Foundation of Zhejiang Province(LZ22A020004)。
文摘With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others without the protection of face masks,which greatly increases the risk of COVID-19 transmission.Therefore,the transmission mechanism of respiratory droplets in extremely crowded dining environments should be investigated.In this study,a numerical simulation of coughing at dining tables under two conditions was performed,namely the presence and absence of protective partitions,and the evaporation and condensation of aerosol droplets in the air were examined.By using the numerical method,we analyzed and verified the isolation effect of dining table partitions in the propagation of aerosol droplets.The effect of changes in room temperature on the diffusion of coughed aerosols when partitions were present was analyzed.We demonstrated how respiratory droplets spread through coughing and how these droplets affect others.Finally,we proposed a design for a dining table partition that minimizes the transmission of COVID-19.
文摘The superplastic deformation behavior of SiCw/ZK60 composite was investigated at temperatures ranging from 573K to 723K and at initial strain rates ranging from 8.3x10-4s-1 to 8.3x10-2s-1. A maximum elongation of 200% with a m-value of 0.35 was obtained at 613K and a initial strain rate of 1.67x 10-2s-1. The apparent activation energy (98kJ/mol) approximates that for grain boundary diffusion (92kJ/mol) in magnesium. It is proposed that the dominant mechanism of superplastic deformation in the present composite is grain boundary sliding accommodated by diffusional transport, besides, interfacial sliding plays an important role in the superplastic deformation.
基金Research and Technology French Agency for funding this study within the framework of convention CIFRE number 2019/1492.
文摘Phenolic compounds are major bioactive chemicals in plant-based food products with proven health benefits.However,alkaline pH processing promotes phenolic compounds auto-oxidation,leading to a loss in food products and by-products.A phenolic-rich brewery effluent,representative of plant-based food matrices,was subdued to aging tests to investigate phenolic compounds stability in different conditions.Three conditions were tested:pH 2 in atmospheric air,pH 13.5 in atmospheric air and under N2 flow.Studied phenolic compounds remained stable in acid pH and alkaline pH under N2 but decreased sharply in alkaline pH.Interestingly,global antioxidant capacity was either stable or degraded according to antioxidant assay performed.Phenolic compounds and their corresponding antioxidant capacity study with coupled HPLC-antioxidant capacity showed that their chemical structure drove their stability.Flavan-3-ols were the main compounds prone to auto-oxidation,followed by catechol acids.Monohydroxy phenolic acids were resistant to major auto-oxidation.This study highlights food phenolic compounds behavior with consequences on antioxidant capacity in a real agro-food system in extreme alkaline condition.
