The microstructure and dry sliding wear behav- ior of cast Al-18 wt% MgaSi in-situ metal matrix com- posite modified by Nd were investigated. Experimental results show that, after introducing a proper amount of Nd, bo...The microstructure and dry sliding wear behav- ior of cast Al-18 wt% MgaSi in-situ metal matrix com- posite modified by Nd were investigated. Experimental results show that, after introducing a proper amount of Nd, both primary and eutectic Mg2Si in the Al-18 wt% Mg2Si composite are well modified. The morphology of primary Mg2Si is changed from irregular or dendritic to polyhedral shape, and its average particle size is signifi- cantly decreased. Moreover, the morphology of the eutectic MgzSi phase is altered from flake-like to very short fibrous or dot-like. The wear rates and friction coefficient of the composites with Nd are lower than those without Nd. Furthermore, the addition of 0.5 wt% Nd changes the wear mechanism of the composite from the combination of abrasive, adhesive, and delamination wear without Nd into a single mild abrasion wear with 0.5 wt% Nd.展开更多
Plums(Prunus domestica L.)are highly valued for their nutritional benefits,antioxidant properties,and economic significance in the dried fruit industry.However,optimizing their drying process while preserving bioactiv...Plums(Prunus domestica L.)are highly valued for their nutritional benefits,antioxidant properties,and economic significance in the dried fruit industry.However,optimizing their drying process while preserving bioactive compounds remains a challenge due to the structural and biochemical changes occurring during ripening.Although extensive research has been conducted on post-harvest drying techniques of plums,the influence of ripening on fruit physicochemical properties,which in turn affects drying characteristics and final dried product quality,has not been sufficiently explored.In this study,plums were categorized into six ripening stages(S1-S6),and their physicochemical characteristics,enzymatic activities,polysaccharide composition,water mobility,drying behavior,and phenolic profiles were systematically analyzed.Results indicated that enzymatic activities of pectin methylesterase,polygalacturonase,and cellulase increased with ripening,leading to cell wall degradation and enhanced water mobility.Chlorogenic acid,quercetin,and procyanidin B1 were the dominant phenolic compounds,with the highest concentrations observed at the S4 stage.The S4 stage exhibited the shortest drying time(12.9 h)and lowest specific energy consumption(7.65 kW・h/kg),while retaining the highest total phenolics(40.19 mg/g DW),ascorbic acid(40.27%retention),and antioxidant activity.Overripe plums(S5-S6)suffered from structural collapse,prolonged drying,and significant phenolic degradation.This study highlights the critical role of ripening in optimizing drying efficiency and bioactive compound retention,providing a novel approach to improving dried plum quality.展开更多
基金financially supported by the National Natural Youth Science Foundation of China (No. 50901038)the Key Laboratory Foundation of Liaoning Provincial Committee of Education (Nos. 20060394 and 2009S053)
文摘The microstructure and dry sliding wear behav- ior of cast Al-18 wt% MgaSi in-situ metal matrix com- posite modified by Nd were investigated. Experimental results show that, after introducing a proper amount of Nd, both primary and eutectic Mg2Si in the Al-18 wt% Mg2Si composite are well modified. The morphology of primary Mg2Si is changed from irregular or dendritic to polyhedral shape, and its average particle size is signifi- cantly decreased. Moreover, the morphology of the eutectic MgzSi phase is altered from flake-like to very short fibrous or dot-like. The wear rates and friction coefficient of the composites with Nd are lower than those without Nd. Furthermore, the addition of 0.5 wt% Nd changes the wear mechanism of the composite from the combination of abrasive, adhesive, and delamination wear without Nd into a single mild abrasion wear with 0.5 wt% Nd.
基金supported by the Guiding Project of the Eighth Division of Xinjiang Production and Construction Corps(grant number 2024ZDGY02).
文摘Plums(Prunus domestica L.)are highly valued for their nutritional benefits,antioxidant properties,and economic significance in the dried fruit industry.However,optimizing their drying process while preserving bioactive compounds remains a challenge due to the structural and biochemical changes occurring during ripening.Although extensive research has been conducted on post-harvest drying techniques of plums,the influence of ripening on fruit physicochemical properties,which in turn affects drying characteristics and final dried product quality,has not been sufficiently explored.In this study,plums were categorized into six ripening stages(S1-S6),and their physicochemical characteristics,enzymatic activities,polysaccharide composition,water mobility,drying behavior,and phenolic profiles were systematically analyzed.Results indicated that enzymatic activities of pectin methylesterase,polygalacturonase,and cellulase increased with ripening,leading to cell wall degradation and enhanced water mobility.Chlorogenic acid,quercetin,and procyanidin B1 were the dominant phenolic compounds,with the highest concentrations observed at the S4 stage.The S4 stage exhibited the shortest drying time(12.9 h)and lowest specific energy consumption(7.65 kW・h/kg),while retaining the highest total phenolics(40.19 mg/g DW),ascorbic acid(40.27%retention),and antioxidant activity.Overripe plums(S5-S6)suffered from structural collapse,prolonged drying,and significant phenolic degradation.This study highlights the critical role of ripening in optimizing drying efficiency and bioactive compound retention,providing a novel approach to improving dried plum quality.
