The dimensional change,residual stress,grain orientation difference,dislocation density,and dislocation distribution of beryllium after different hot isostatic pressing treatments were analyzed by laser length meter,R...The dimensional change,residual stress,grain orientation difference,dislocation density,and dislocation distribution of beryllium after different hot isostatic pressing treatments were analyzed by laser length meter,Raman spectrometer,nanoindentation meter,electron backscattered diffractometer,and transmission electron microscope,and the influence of thermal-cold cycling treatment on the dimensional stability of beryllium was analyzed.Results show that the size of the hot isostatic pressed beryllium tends to be stable after 6 cycles of thermal-cold cycling treatment from-100℃to 150℃,and it has good dimensional stability.The dimensional stabilization mechanism of beryllium is mainly the homogenization of dislocations within the grain and the homogenization of orientation difference caused by micro-plastic deformation.展开更多
The storage and transportation of raw milk at low temperatures promote the growth of psychrotrophic bacteria and the production of thermo-stable enzymes, which pose great threats to the quality and shelf-life of dairy...The storage and transportation of raw milk at low temperatures promote the growth of psychrotrophic bacteria and the production of thermo-stable enzymes, which pose great threats to the quality and shelf-life of dairy products. Though many studies have been carried out on the spoilage potential of psychrotrophic bacteria and the thermo-stabUities of the enzymes they produce, further detailed studies are needed to devise an effective strategy to avoid dairy spoilage. The purpose of this study was to explore the spoilage potential of psychrotrophic bacteria from Chinese raw milk samples at both room temperature （28 ℃） and refrigerated temperature （7 ℃）. Species of Yersinia, Pseudomonas, Serratia, and Chryseobacterium showed high proteolytic activity. The highest proteolytic activity was shown by Yersinia intermedia followed by Pseudomonas fluorescens （d）. Lipolytic activity was high in isolates of Acinetobacter, and the highest in Acinetobacter guillouiae. Certain isolates showed positive ^-galactosidase and phospholipase activity. Strains belonging to the same species sometimes showed markedly different phenotypic characteristics. Proteases and lipases produced by psychrotrophic bacteria retained activity after heat treatment at 70, 80, or 90 ℃, and proteases appeared to be more heat-stable than lipases. For these reasons, thermo-stable spoilage enzymes produced by a high number of psychrotrophic bacterial isolates from raw milk are of major concern to the dairy industry. The results of this study provide valuable data about the spoilage potential of bacterial strains in raw milk and the thermal resistance of the enzymes they produce.展开更多
This paper presents an application of finite element method to study the thermoreg- ulatory behavior of three layers of human dermal parts with varying properties. The investigation of temperature distributions in epi...This paper presents an application of finite element method to study the thermoreg- ulatory behavior of three layers of human dermal parts with varying properties. The investigation of temperature distributions in epidermis, dermis and subcutaneous tissue together with Crank-Nicholson scheme at various atmospheric conditions was carried out. The finite element method has been applied to obtain the numerical solution of gov- erning differential equation for one-dimensional unsteady state bioheat equation using suitable values of parameters that affect the heat transfer in human body. The outer skin is assumed to be exposed to cold atmospheric temperatures and the loss of heat due to convection, radiation and evaporation has been taken into consideration. The important parameters like blood mass flow rate, metabolic heat generation rate and thermal conductivity are taken heterogeneous in each layer according to their distinct physiological and biochemical activities. The temperature profiles at various nodal points of the skin and in vivo tissues have been calculated with respect to the severe cold ambient temperatures. The conditions under which hypothermia, non-freezing and freezing injuries develop were illustrated in the graphs.展开更多
基金National Defense Basic Scientific Research Program of China(JCKY2018203B067)Youth Natural Science Foundation of Hunan Province(2019JJ50817)。
文摘The dimensional change,residual stress,grain orientation difference,dislocation density,and dislocation distribution of beryllium after different hot isostatic pressing treatments were analyzed by laser length meter,Raman spectrometer,nanoindentation meter,electron backscattered diffractometer,and transmission electron microscope,and the influence of thermal-cold cycling treatment on the dimensional stability of beryllium was analyzed.Results show that the size of the hot isostatic pressed beryllium tends to be stable after 6 cycles of thermal-cold cycling treatment from-100℃to 150℃,and it has good dimensional stability.The dimensional stabilization mechanism of beryllium is mainly the homogenization of dislocations within the grain and the homogenization of orientation difference caused by micro-plastic deformation.
基金Project supported by the National Natural Science Foundation of China(No.31772080)the Major Science and Technology Projects of Zhejiang Province(No.2015C02039),China
文摘The storage and transportation of raw milk at low temperatures promote the growth of psychrotrophic bacteria and the production of thermo-stable enzymes, which pose great threats to the quality and shelf-life of dairy products. Though many studies have been carried out on the spoilage potential of psychrotrophic bacteria and the thermo-stabUities of the enzymes they produce, further detailed studies are needed to devise an effective strategy to avoid dairy spoilage. The purpose of this study was to explore the spoilage potential of psychrotrophic bacteria from Chinese raw milk samples at both room temperature （28 ℃） and refrigerated temperature （7 ℃）. Species of Yersinia, Pseudomonas, Serratia, and Chryseobacterium showed high proteolytic activity. The highest proteolytic activity was shown by Yersinia intermedia followed by Pseudomonas fluorescens （d）. Lipolytic activity was high in isolates of Acinetobacter, and the highest in Acinetobacter guillouiae. Certain isolates showed positive ^-galactosidase and phospholipase activity. Strains belonging to the same species sometimes showed markedly different phenotypic characteristics. Proteases and lipases produced by psychrotrophic bacteria retained activity after heat treatment at 70, 80, or 90 ℃, and proteases appeared to be more heat-stable than lipases. For these reasons, thermo-stable spoilage enzymes produced by a high number of psychrotrophic bacterial isolates from raw milk are of major concern to the dairy industry. The results of this study provide valuable data about the spoilage potential of bacterial strains in raw milk and the thermal resistance of the enzymes they produce.
文摘This paper presents an application of finite element method to study the thermoreg- ulatory behavior of three layers of human dermal parts with varying properties. The investigation of temperature distributions in epidermis, dermis and subcutaneous tissue together with Crank-Nicholson scheme at various atmospheric conditions was carried out. The finite element method has been applied to obtain the numerical solution of gov- erning differential equation for one-dimensional unsteady state bioheat equation using suitable values of parameters that affect the heat transfer in human body. The outer skin is assumed to be exposed to cold atmospheric temperatures and the loss of heat due to convection, radiation and evaporation has been taken into consideration. The important parameters like blood mass flow rate, metabolic heat generation rate and thermal conductivity are taken heterogeneous in each layer according to their distinct physiological and biochemical activities. The temperature profiles at various nodal points of the skin and in vivo tissues have been calculated with respect to the severe cold ambient temperatures. The conditions under which hypothermia, non-freezing and freezing injuries develop were illustrated in the graphs.
