车轮多边形磨损是地铁车辆运营过程中经常出现的现象,该现象易导致车辆和轨道结构发生异常振动。针对国内某地铁线路,在现场测试车轮多边形磨损状态基础上,通过测试对比有、无车轮多边形磨损的车辆通过地铁线路减振式钢弹簧浮置板道床...车轮多边形磨损是地铁车辆运营过程中经常出现的现象,该现象易导致车辆和轨道结构发生异常振动。针对国内某地铁线路,在现场测试车轮多边形磨损状态基础上,通过测试对比有、无车轮多边形磨损的车辆通过地铁线路减振式钢弹簧浮置板道床段和非减振普通整体道床段时的轨道振动加速度,研究地铁车轮多边形磨损状态对轨道振动大小和减振特性的影响。结果表明:调查的地铁线路列车车轮存在13阶~17阶多边形磨损,其粗糙度平均水平为21.3 d B re 1μm;当存在车轮多边形磨损的列车通过浮置板轨道时,钢轨、弹条、轨枕、道床、隧道壁测点的垂向振动加速度均方根值分别为105.09 m/s2、154.41 m/s2、13.04 m/s2、8.16 m/s2、0.028 m/s2,与无车轮多边形磨损列车通过时相比,振动水平分别增大了137.5%、145.3%、105.4%、111.9%、75.0%。车轮多边形磨损对浮置板轨道的道床板及其以上部件振动水平的影响比对普通整体道床轨道的更显著,对浮置板轨道隧道壁振动的影响则小于对普通整体道床轨道隧道壁的影响。存在车轮多边形磨损的车辆通过浮置板轨道时,通过频率为61 Hz^104 Hz,易激发轨道的整体垂向弯曲共振模态,引起道床板振动幅值过大。在运行列车有、无13阶~17阶多边形磨损时,钢弹簧浮置板轨道减振量分别为29.33 d B和35.11 d B,车轮多边形磨损的存在降低浮置板轨道的减振效果。展开更多
Mitigative effect of La on Glycine max seedlings under combined Pb and Cd pollution was studied through pot culture experiment. The results show that the growth and metabolism of Glycine max seedlings are inhibited by...Mitigative effect of La on Glycine max seedlings under combined Pb and Cd pollution was studied through pot culture experiment. The results show that the growth and metabolism of Glycine max seedlings are inhibited by the solution with 500 mg.L-1 Pb + 100 mg.L-1 Cd. When 30 mg. L-1 LaCl3 is used to spray Glycine max seedlings once, the injury effect of combined Pb and Cd pollution is reduced. The experiment proves that the effect is related to La which can raise photosynthetic rate, chlorophyll content and activity of nitrate reductase, and reduce cell membrane permeability, content of Pb and Cd, and keep TTC reduction ability of Glycine max seedling.展开更多
Temperature extremes represent an important limiting factor to plant growth and productivity. Low concentration of hydrogen sulfide （H2S） has been proven to function in physiological responses to various stresses. T...Temperature extremes represent an important limiting factor to plant growth and productivity. Low concentration of hydrogen sulfide （H2S） has been proven to function in physiological responses to various stresses. The present study evaluated the effect of foliar application of wheat seedlings with a H2S donor, sodium hydrosulfide （NariS）, on the response to acute heat stress. The results showed that pretreatment with NariS could promote heat tolerance of wheat seedlings in a dose-depen- dent manner. Again, it was verified that H2S, rather than other sulfur-containing components or sodion derived from NariS solution, should contribute to the positive role in promoting wheat seedlings against heat stress. To further study antioxidant mechanisms of NariS-induced heat tolerance, superoxide dismutase （SOD, EC 1.15.1.1 ）, catalase （CAT, EC 1.11.1.6） and ascorbate peroxidase （APX, EC 1.11.1.11 ） activities, and HzS, hydrogen peroxide （H2O2）, malonaldehyde （MDA）, and soluble sugar contents in wheat seedlings were determined. The results showed that, under heat stress, the activities of SOD, CAT, and APX, H2S, H2O2, MDA, and soluble sugar contents in NaHS-pretreated seedlings and its control all increased. Meanwhile, NaHS-pretreated seedlings showed higher antioxidant enzymes activities and gene expression levels as well as the H2S and soluble sugar levels, and lower H2O2, MDA contents induced by heat stress. While little effect was detected in antioxidant enzymes activities and soluble substances contents in pretreated wheat seedlings compared with its control under normal culture conditions （data not shown）. All of our results suggested that exogenous NariS could alleviate oxidative damage and improve heat tolerance by regulating the antioxidant system in wheat seedlings under heat stress.展开更多
文摘车轮多边形磨损是地铁车辆运营过程中经常出现的现象,该现象易导致车辆和轨道结构发生异常振动。针对国内某地铁线路,在现场测试车轮多边形磨损状态基础上,通过测试对比有、无车轮多边形磨损的车辆通过地铁线路减振式钢弹簧浮置板道床段和非减振普通整体道床段时的轨道振动加速度,研究地铁车轮多边形磨损状态对轨道振动大小和减振特性的影响。结果表明:调查的地铁线路列车车轮存在13阶~17阶多边形磨损,其粗糙度平均水平为21.3 d B re 1μm;当存在车轮多边形磨损的列车通过浮置板轨道时,钢轨、弹条、轨枕、道床、隧道壁测点的垂向振动加速度均方根值分别为105.09 m/s2、154.41 m/s2、13.04 m/s2、8.16 m/s2、0.028 m/s2,与无车轮多边形磨损列车通过时相比,振动水平分别增大了137.5%、145.3%、105.4%、111.9%、75.0%。车轮多边形磨损对浮置板轨道的道床板及其以上部件振动水平的影响比对普通整体道床轨道的更显著,对浮置板轨道隧道壁振动的影响则小于对普通整体道床轨道隧道壁的影响。存在车轮多边形磨损的车辆通过浮置板轨道时,通过频率为61 Hz^104 Hz,易激发轨道的整体垂向弯曲共振模态,引起道床板振动幅值过大。在运行列车有、无13阶~17阶多边形磨损时,钢弹簧浮置板轨道减振量分别为29.33 d B和35.11 d B,车轮多边形磨损的存在降低浮置板轨道的减振效果。
文摘Mitigative effect of La on Glycine max seedlings under combined Pb and Cd pollution was studied through pot culture experiment. The results show that the growth and metabolism of Glycine max seedlings are inhibited by the solution with 500 mg.L-1 Pb + 100 mg.L-1 Cd. When 30 mg. L-1 LaCl3 is used to spray Glycine max seedlings once, the injury effect of combined Pb and Cd pollution is reduced. The experiment proves that the effect is related to La which can raise photosynthetic rate, chlorophyll content and activity of nitrate reductase, and reduce cell membrane permeability, content of Pb and Cd, and keep TTC reduction ability of Glycine max seedling.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest of China (201203029)
文摘Temperature extremes represent an important limiting factor to plant growth and productivity. Low concentration of hydrogen sulfide （H2S） has been proven to function in physiological responses to various stresses. The present study evaluated the effect of foliar application of wheat seedlings with a H2S donor, sodium hydrosulfide （NariS）, on the response to acute heat stress. The results showed that pretreatment with NariS could promote heat tolerance of wheat seedlings in a dose-depen- dent manner. Again, it was verified that H2S, rather than other sulfur-containing components or sodion derived from NariS solution, should contribute to the positive role in promoting wheat seedlings against heat stress. To further study antioxidant mechanisms of NariS-induced heat tolerance, superoxide dismutase （SOD, EC 1.15.1.1 ）, catalase （CAT, EC 1.11.1.6） and ascorbate peroxidase （APX, EC 1.11.1.11 ） activities, and HzS, hydrogen peroxide （H2O2）, malonaldehyde （MDA）, and soluble sugar contents in wheat seedlings were determined. The results showed that, under heat stress, the activities of SOD, CAT, and APX, H2S, H2O2, MDA, and soluble sugar contents in NaHS-pretreated seedlings and its control all increased. Meanwhile, NaHS-pretreated seedlings showed higher antioxidant enzymes activities and gene expression levels as well as the H2S and soluble sugar levels, and lower H2O2, MDA contents induced by heat stress. While little effect was detected in antioxidant enzymes activities and soluble substances contents in pretreated wheat seedlings compared with its control under normal culture conditions （data not shown）. All of our results suggested that exogenous NariS could alleviate oxidative damage and improve heat tolerance by regulating the antioxidant system in wheat seedlings under heat stress.
