A significant temperature raise within hydrogen vehicle cylinder during the fast filling process will be observed, while the strength and fatigue life of the cylinder will dramatically decrease at high temperature. In...A significant temperature raise within hydrogen vehicle cylinder during the fast filling process will be observed, while the strength and fatigue life of the cylinder will dramatically decrease at high temperature. In order to evaluate the strength and fatigue of composite hydrogen storage vessel, a 70-MPa fatigue test system using hydrogen medium was set up. Experimental study on the fatigue of composite hydrogen storage vessels under real hydrogen environment was performed. The experimental results show that the ultimate strength and fatigue life both decreased obviously compared with the values under hydraulic fatigue test. Furthermore, fatigue property, failure behavior, and safe hydrogen charging/discharging working mode of onboard hydrogen storage vessels were obtained through the fatigue tests.展开更多
【目的】通过比较两种不同杀菌处理(高温短时High temperature short-time和超高压Ultra-high pressure杀菌)的非浓缩还原(Not from concentrate,NFC)苹果汁贮藏期品质变化,为我国NFC果汁产品标准的制定和规范市场NFC果汁产品货架期提...【目的】通过比较两种不同杀菌处理(高温短时High temperature short-time和超高压Ultra-high pressure杀菌)的非浓缩还原(Not from concentrate,NFC)苹果汁贮藏期品质变化,为我国NFC果汁产品标准的制定和规范市场NFC果汁产品货架期提供试验依据。【方法】以‘红富士’苹果为原料制备NFC苹果汁,采用高温短时杀菌(HTST,98℃,50 s)和超高压杀菌(UHP,400 MPa,15 min)处理后,在4℃条件下冷藏,利用微生物学、化学及主成分分析(PCA)等方法以及HPLC、GC-MS等手段研究两种不同杀菌处理的NFC苹果汁贮藏期微生物、理化指标、多酚含量、酶(Polyphenol oxidase,PPO;Peroxidase,POD)活性、抗氧化活性、香气成分的变化。【结果】HTST和UHP处理对细菌总数、大肠杆菌、霉菌与酵母的杀菌率均为100%,但贮藏第10、5周时果汁菌落总数分别呈显著增加(89.15%、58.65%),大肠杆菌、霉菌与酵母增殖速度不明显;贮藏期HTST和UHP两种处理NFC苹果汁微生物种群变化小,但优势菌属不同。两种处理的NFC苹果汁贮藏期可溶性固形物、pH、总酸的变化不大,但总色差显著增大(P<0.05);贮藏期HTST和UHP处理NFC苹果汁中表儿茶素分别下降了33%和53%,FRAP总抗氧化能力和DPPH自由基清除率分别保持在76%、73%和77%、76%,HTST处理NFC苹果汁的多酚含量和抗氧化活性明显高于UHP处理的样品;HTST处理后贮藏期NFC苹果汁的PPO与POD完全失活,但UHP处理样品的酶活性呈现先增大后降低的趋势。HTST处理后果汁18种特征香味物质总的保留率为52%,但贮藏期香气成分保持稳定;UHP处理NFC苹果汁的香气含量(57.75 mg/100 mL)接近对照样品(57.17 mg/100 mL),但贮藏期香气成分变化显著,降低了26.13%。【结论】HTST和UHP杀菌处理的NFC苹果汁在4℃可分别贮藏9、4周,贮藏期内其品质满足商业要求,HTST处理NFC苹果汁货架期长于UHP处理。展开更多
为研究贮藏温度对高温高压海参体壁组织结构变化的影响,将预处理后的刺参组织分别在4、20、37、50和60 ℃进行恒温贮藏。通过质构(texture profile analysis,TPA)参数、水分状态、扫描电镜(scanning electron microscopy,SEM)和透射电镜...为研究贮藏温度对高温高压海参体壁组织结构变化的影响,将预处理后的刺参组织分别在4、20、37、50和60 ℃进行恒温贮藏。通过质构(texture profile analysis,TPA)参数、水分状态、扫描电镜(scanning electron microscopy,SEM)和透射电镜(transmission electron microscopy,TEM)图像的变化情况,研究贮藏温度对高温高压海参体壁稳定性的影响。结果表明,高温高压热处理过程中微生物和内源酶已完全失活,并且在贮藏0~30 d过程中仍然保持失活状态。在高温高压热处理过程中,胶原纤维束的结构被破坏,胶原蛋白的三螺旋结构也逐渐解旋和降解。在贮藏过程中,胶原纤维束和胶原蛋白的结构被进一步破坏和降解,且被破坏的程度与贮藏温度呈正相关。因此,可以通过降低贮藏温度进而有效地减小对组织结构的破坏程度,从而延长高温高压海参产品的货架期。展开更多
文摘A significant temperature raise within hydrogen vehicle cylinder during the fast filling process will be observed, while the strength and fatigue life of the cylinder will dramatically decrease at high temperature. In order to evaluate the strength and fatigue of composite hydrogen storage vessel, a 70-MPa fatigue test system using hydrogen medium was set up. Experimental study on the fatigue of composite hydrogen storage vessels under real hydrogen environment was performed. The experimental results show that the ultimate strength and fatigue life both decreased obviously compared with the values under hydraulic fatigue test. Furthermore, fatigue property, failure behavior, and safe hydrogen charging/discharging working mode of onboard hydrogen storage vessels were obtained through the fatigue tests.
文摘为研究贮藏温度对高温高压海参体壁组织结构变化的影响,将预处理后的刺参组织分别在4、20、37、50和60 ℃进行恒温贮藏。通过质构(texture profile analysis,TPA)参数、水分状态、扫描电镜(scanning electron microscopy,SEM)和透射电镜(transmission electron microscopy,TEM)图像的变化情况,研究贮藏温度对高温高压海参体壁稳定性的影响。结果表明,高温高压热处理过程中微生物和内源酶已完全失活,并且在贮藏0~30 d过程中仍然保持失活状态。在高温高压热处理过程中,胶原纤维束的结构被破坏,胶原蛋白的三螺旋结构也逐渐解旋和降解。在贮藏过程中,胶原纤维束和胶原蛋白的结构被进一步破坏和降解,且被破坏的程度与贮藏温度呈正相关。因此,可以通过降低贮藏温度进而有效地减小对组织结构的破坏程度,从而延长高温高压海参产品的货架期。
