In this study, density measurements were observed by using gamma transmission technique. Co-60 gamma emitter was used as gamma radioisotope source. Regarding the gamma-ray transmission method, initial radiation intens...In this study, density measurements were observed by using gamma transmission technique. Co-60 gamma emitter was used as gamma radioisotope source. Regarding the gamma-ray transmission method, initial radiation intensity （I0） and radiation intensity （I） determined experimentally and [I/I0] rates were calculated and then density of materials could be determined by using Beer-Lambert Equation. Experimental application performed on widespread industrial metals or metal alloys e.g. lead, copper and steel, brass. With this study, it is shown that gamma transmission technique can be used for density measurements.展开更多
为探究^(60)Co-γ辐照对苦荞麸皮中黄酮类物质提取效率的影响,本研究采用不同剂量(0、6、12、18、24、30 k Gy)的^(60)Co-γ对苦荞麸皮进行辐照预处理,通过热回流法提取苦荞黄酮,比较^(60)Co-γ辐照对苦荞黄酮提取得率、主要黄酮类物质...为探究^(60)Co-γ辐照对苦荞麸皮中黄酮类物质提取效率的影响,本研究采用不同剂量(0、6、12、18、24、30 k Gy)的^(60)Co-γ对苦荞麸皮进行辐照预处理,通过热回流法提取苦荞黄酮,比较^(60)Co-γ辐照对苦荞黄酮提取得率、主要黄酮类物质单体含量和总含量、抑菌活性及苦荞麸皮微观结构的影响。结果表明,6~30 k Gy剂量的^(60)Co-γ辐照预处理可提高苦荞黄酮提取得率,其中12 k Gy组提取得率最高,为6.97%,较对照组的3.27%提高3.70个百分点;6~30 k Gy剂量的^(60)Co-γ辐照预处理可提高提取物中芦丁含量,12、18、30 k Gy剂量的预处理可提高提取物中烟花苷含量,其中12 k Gy组含量最高,芦丁和烟花苷含量分别为84.52、3.92 mg·g^(-1),较对照组的53.12、3.54 mg·g^(-1)分别提高59.11%与10.73%;6~24 k Gy剂量的^(60)Co-γ辐照预处理可提高苦荞主要黄酮总含量,其中12 k Gy组最高,为89.40 mg·g^(-1),较对照组的57.95 mg·g^(-1)提高54.27%。此外,^(60)Co-γ辐照可有效破坏苦荞麸皮组织结构,有助于苦荞黄酮的溶出;6~18 k Gy剂量的^(60)Co-γ辐照预处理增强了提取物对大肠杆菌的抑菌活性,其中18 k Gy剂量组的抑菌活性最强,抑菌圈直径达9.93 mm;12~24 k Gy剂量的^(60)Co-γ辐照预处理增强了提取物对金黄色葡萄球菌的抑菌活性,其中12 k Gy剂量组的抑菌活性最强,抑菌圈直径达10.30 mm。本研究可为苦荞黄酮的高效提取提供研究基础与技术参考。展开更多
Based on the NCEP/NCAR reanalysis data and the observed precipitation data in the south of China from 1958 to 2000,the impact of 30 to 60 day oscillation of atmospheric heat sources on the drought and flood events in ...Based on the NCEP/NCAR reanalysis data and the observed precipitation data in the south of China from 1958 to 2000,the impact of 30 to 60 day oscillation of atmospheric heat sources on the drought and flood events in June in the south of China is discussed.During the flood(drought) events,there exists an anomalous low-frequency anticyclone(cyclone) at the low level of the troposphere over the South China Sea and the northwestern Pacific,accompanied with anomalous low-frequency heat sinks(heat sources),while there exists an anomalous low-frequency cyclone(anticyclone) with anomalous heat sources(sinks) over the area from the south of China to the south of Japan.On average,the phase evolution of the low-frequency in drought events is 7 to 11 days ahead of that in flood events in May to June in the south of China.In flood events,low-frequency heat sources and cyclones are propagated northward from the southern South China Sea,northwestward from the warm pool of the western Pacific and westward from the northwestern Pacific around 140°E,which have very important impact on the abundant rainfall in June in the south of China.However,in drought events,the northward propagations of the low-frequency heat sources and cyclones from the South China Sea and its vicinity are rather late compared with those in flood events,and there is no obvious westward propagation of the heat sources from the northwestern Pacific.The timing of the low-frequency heat source propagation has remarkable impact on the June rainfall in the south of China.展开更多
文摘In this study, density measurements were observed by using gamma transmission technique. Co-60 gamma emitter was used as gamma radioisotope source. Regarding the gamma-ray transmission method, initial radiation intensity （I0） and radiation intensity （I） determined experimentally and [I/I0] rates were calculated and then density of materials could be determined by using Beer-Lambert Equation. Experimental application performed on widespread industrial metals or metal alloys e.g. lead, copper and steel, brass. With this study, it is shown that gamma transmission technique can be used for density measurements.
文摘为探究^(60)Co-γ辐照对苦荞麸皮中黄酮类物质提取效率的影响,本研究采用不同剂量(0、6、12、18、24、30 k Gy)的^(60)Co-γ对苦荞麸皮进行辐照预处理,通过热回流法提取苦荞黄酮,比较^(60)Co-γ辐照对苦荞黄酮提取得率、主要黄酮类物质单体含量和总含量、抑菌活性及苦荞麸皮微观结构的影响。结果表明,6~30 k Gy剂量的^(60)Co-γ辐照预处理可提高苦荞黄酮提取得率,其中12 k Gy组提取得率最高,为6.97%,较对照组的3.27%提高3.70个百分点;6~30 k Gy剂量的^(60)Co-γ辐照预处理可提高提取物中芦丁含量,12、18、30 k Gy剂量的预处理可提高提取物中烟花苷含量,其中12 k Gy组含量最高,芦丁和烟花苷含量分别为84.52、3.92 mg·g^(-1),较对照组的53.12、3.54 mg·g^(-1)分别提高59.11%与10.73%;6~24 k Gy剂量的^(60)Co-γ辐照预处理可提高苦荞主要黄酮总含量,其中12 k Gy组最高,为89.40 mg·g^(-1),较对照组的57.95 mg·g^(-1)提高54.27%。此外,^(60)Co-γ辐照可有效破坏苦荞麸皮组织结构,有助于苦荞黄酮的溶出;6~18 k Gy剂量的^(60)Co-γ辐照预处理增强了提取物对大肠杆菌的抑菌活性,其中18 k Gy剂量组的抑菌活性最强,抑菌圈直径达9.93 mm;12~24 k Gy剂量的^(60)Co-γ辐照预处理增强了提取物对金黄色葡萄球菌的抑菌活性,其中12 k Gy剂量组的抑菌活性最强,抑菌圈直径达10.30 mm。本研究可为苦荞黄酮的高效提取提供研究基础与技术参考。
基金National Key Program for Developing Basic Research (2009CB421404)Key Program of National Science Foundation of China (40730951)Program of National Science Foundation of China(40605028)
文摘Based on the NCEP/NCAR reanalysis data and the observed precipitation data in the south of China from 1958 to 2000,the impact of 30 to 60 day oscillation of atmospheric heat sources on the drought and flood events in June in the south of China is discussed.During the flood(drought) events,there exists an anomalous low-frequency anticyclone(cyclone) at the low level of the troposphere over the South China Sea and the northwestern Pacific,accompanied with anomalous low-frequency heat sinks(heat sources),while there exists an anomalous low-frequency cyclone(anticyclone) with anomalous heat sources(sinks) over the area from the south of China to the south of Japan.On average,the phase evolution of the low-frequency in drought events is 7 to 11 days ahead of that in flood events in May to June in the south of China.In flood events,low-frequency heat sources and cyclones are propagated northward from the southern South China Sea,northwestward from the warm pool of the western Pacific and westward from the northwestern Pacific around 140°E,which have very important impact on the abundant rainfall in June in the south of China.However,in drought events,the northward propagations of the low-frequency heat sources and cyclones from the South China Sea and its vicinity are rather late compared with those in flood events,and there is no obvious westward propagation of the heat sources from the northwestern Pacific.The timing of the low-frequency heat source propagation has remarkable impact on the June rainfall in the south of China.
