Hygroscopicity-resistance of an α-starch based composite binder for dry sand molds (cores) has been studiedexperimentally and theoretically. Focus is placed on the relationship between the hardening structure andhumi...Hygroscopicity-resistance of an α-starch based composite binder for dry sand molds (cores) has been studiedexperimentally and theoretically. Focus is placed on the relationship between the hardening structure andhumidity-resistance of the composite binder. The results show that the α-starch composite binder has goodhumidity-resistance due to its special complex structure. SEM observations illustrate that the composite binder consists ofreticular matrix and a ball- or lump-shaped reinforcement phase, and the specific property of the binding membrane withheterogeneous structure is affected by humidity to a small extent. Based on the analyses on the interplays of differentingredients in the binder at hardening, the structure model and hygroscopicity-resistant mechanisms of the hardeningcomposite binder were further proposed. Moreover, the reasons for good humidity-resistance of the composite binderbonded sand are well explained by the humidity-resistant mechanisms.展开更多
目的探究不同品种白茶水提物对高温胁迫下果蝇存活能力的影响,筛选对热应激有防护作用的白茶品种。方法选取黑腹果蝇为模式生物,在基础培养基中分别添加不同茶水比[3:100、5:100、7:100、9:100、11:100(g/mL)]浸提的白毫银针、白牡丹、...目的探究不同品种白茶水提物对高温胁迫下果蝇存活能力的影响,筛选对热应激有防护作用的白茶品种。方法选取黑腹果蝇为模式生物,在基础培养基中分别添加不同茶水比[3:100、5:100、7:100、9:100、11:100(g/mL)]浸提的白毫银针、白牡丹、贡眉及寿眉水提物,观察各培养基饲喂的果蝇在36℃热暴露下的存活情况。选取提高果蝇热耐受能力最佳的白茶品种进行热锻炼实验。结果适当茶水比浸提的4种白茶水提物不同程度地延长了雌性果蝇的半数致死时间(lethal time of 50%,LT50)、平均存活时间(mean survival time,T)及最高存活时间(maximum survival time,Tmax),提高了雌性果蝇热耐受能力,但不存在剂量-效应关系。白毫银针水提物改善雌性果蝇热耐受能力的作用最佳,4种白茶水提物改善雌性果蝇热耐受能力对应的最佳茶水比均为9:100(g/mL)。热锻炼可提高雌性果蝇的热适应能力,9:100 g/mL茶水比浸提的白毫银针水提物极显著地改善了热锻炼后雌性果蝇的热耐受能力(P<0.01)。结论本研究结果可为白茶摄入改善机体对高温的耐受性提供理论依据。展开更多
The survival ability of insects can be limited with the changes in the levels of energy metabolites under stressful conditions but only a few studies have considered the plastic effects of heat and related climatic fa...The survival ability of insects can be limited with the changes in the levels of energy metabolites under stressful conditions but only a few studies have considered the plastic effects of heat and related climatic factors relevant to tropical habitats. The objectives of our study were to determine whether adults of <i><span style="font-family:Verdana;">Zaprionus</span></i> <i><span style="font-family:Verdana;">indianus</span></i><span style="font-family:Verdana;"> are capable of rapid heat hardening (RHH) and rapid desiccation hardening (RDH) and to compare its benefits with heat acclimation (HA) and desiccation acclimation (DA). Adult flies reared under season-specific simulated conditions were subjected to 38<span style="color:#111111;font-family:Roboto, sans-serif;font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C for RHH and 32<span style="color:#111111;font-family:Roboto, sans-serif;font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C for HA, while 5% relative humidity (RH) was maintained for RDH and 40% RH for DA. Stress-induced effects of heat and desiccation on the levels of five metabolites namely cuticular lipids (CL), total body lipids (TBL), protein, proline, and carbohydrates were then estimated by biochemical method. Different duration of heat hardening and acclimation led to more accumulation of CL whereas different durations of desiccation hardening and acclimation revealed less accumulation. In contrast, there was an accumulation of carbohydrates and protein under desiccation hardening and acclimation whereas there was the utilization of carbohydrates and protein under heat hardening and acclimation. However, mixed results were observed on the level of proline and TBL under both heat and desiccation stress. These stress-triggered changes in the levels of various metabolites suggest a possible link between heat and desiccation tolerance. Hence, these compensatory changes in the level of various metabolites also suggest possible energetic homeostasis i展开更多
文摘Hygroscopicity-resistance of an α-starch based composite binder for dry sand molds (cores) has been studiedexperimentally and theoretically. Focus is placed on the relationship between the hardening structure andhumidity-resistance of the composite binder. The results show that the α-starch composite binder has goodhumidity-resistance due to its special complex structure. SEM observations illustrate that the composite binder consists ofreticular matrix and a ball- or lump-shaped reinforcement phase, and the specific property of the binding membrane withheterogeneous structure is affected by humidity to a small extent. Based on the analyses on the interplays of differentingredients in the binder at hardening, the structure model and hygroscopicity-resistant mechanisms of the hardeningcomposite binder were further proposed. Moreover, the reasons for good humidity-resistance of the composite binderbonded sand are well explained by the humidity-resistant mechanisms.
文摘目的探究不同品种白茶水提物对高温胁迫下果蝇存活能力的影响,筛选对热应激有防护作用的白茶品种。方法选取黑腹果蝇为模式生物,在基础培养基中分别添加不同茶水比[3:100、5:100、7:100、9:100、11:100(g/mL)]浸提的白毫银针、白牡丹、贡眉及寿眉水提物,观察各培养基饲喂的果蝇在36℃热暴露下的存活情况。选取提高果蝇热耐受能力最佳的白茶品种进行热锻炼实验。结果适当茶水比浸提的4种白茶水提物不同程度地延长了雌性果蝇的半数致死时间(lethal time of 50%,LT50)、平均存活时间(mean survival time,T)及最高存活时间(maximum survival time,Tmax),提高了雌性果蝇热耐受能力,但不存在剂量-效应关系。白毫银针水提物改善雌性果蝇热耐受能力的作用最佳,4种白茶水提物改善雌性果蝇热耐受能力对应的最佳茶水比均为9:100(g/mL)。热锻炼可提高雌性果蝇的热适应能力,9:100 g/mL茶水比浸提的白毫银针水提物极显著地改善了热锻炼后雌性果蝇的热耐受能力(P<0.01)。结论本研究结果可为白茶摄入改善机体对高温的耐受性提供理论依据。
文摘The survival ability of insects can be limited with the changes in the levels of energy metabolites under stressful conditions but only a few studies have considered the plastic effects of heat and related climatic factors relevant to tropical habitats. The objectives of our study were to determine whether adults of <i><span style="font-family:Verdana;">Zaprionus</span></i> <i><span style="font-family:Verdana;">indianus</span></i><span style="font-family:Verdana;"> are capable of rapid heat hardening (RHH) and rapid desiccation hardening (RDH) and to compare its benefits with heat acclimation (HA) and desiccation acclimation (DA). Adult flies reared under season-specific simulated conditions were subjected to 38<span style="color:#111111;font-family:Roboto, sans-serif;font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C for RHH and 32<span style="color:#111111;font-family:Roboto, sans-serif;font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C for HA, while 5% relative humidity (RH) was maintained for RDH and 40% RH for DA. Stress-induced effects of heat and desiccation on the levels of five metabolites namely cuticular lipids (CL), total body lipids (TBL), protein, proline, and carbohydrates were then estimated by biochemical method. Different duration of heat hardening and acclimation led to more accumulation of CL whereas different durations of desiccation hardening and acclimation revealed less accumulation. In contrast, there was an accumulation of carbohydrates and protein under desiccation hardening and acclimation whereas there was the utilization of carbohydrates and protein under heat hardening and acclimation. However, mixed results were observed on the level of proline and TBL under both heat and desiccation stress. These stress-triggered changes in the levels of various metabolites suggest a possible link between heat and desiccation tolerance. Hence, these compensatory changes in the level of various metabolites also suggest possible energetic homeostasis i
