There are often many chemicals coexisting in aquatic ecosystems, and few information on the joint toxicity of a mixture of organic pollutants is available at present. The 48-h toxicity of substituted phenols and anili...There are often many chemicals coexisting in aquatic ecosystems, and few information on the joint toxicity of a mixture of organic pollutants is available at present. The 48-h toxicity of substituted phenols and anilines and their binary mixtures to Scenedesmus obliquus was determined by the algae inhibition test. The median effective inhibition concentration EC50 values for single compounds and EC50mix values for coexistent compounds were obtained. The n-octanol/water partition coefficient （logPmlx） and the frontier orbital energy gap （AEmlx） for mixtures were calculated. The following two-descriptor quantitative structure-activity relationships （QSARs） models were developed to predict single toxicity and joint toxicity respectively： log（1/ECs0） = 0.445logP - 0.801AE ＋ 9.501 （r2 = 0.876） and log （1/EC50mix） = 0.338logPmix- 0.492AEmix ＋ 6.928 （r^2 = 0.831）. The two equations were found to fit well. In addition, the model derived from the structural parameters of single components in binary mixtures log（1/EC50mix） = 0.2221ogP - 0.277AE ＋ 5.250 （r^2 = 0.879） can be used successfully to predict the toxicity of a mixture.展开更多
The morphology and distribution of residual austenite in the welded zone of 9% Cr/CrMoV dissimilar welded joint were observed by color metallographic method. Moreover, the details of the distribution, shape, length, l...The morphology and distribution of residual austenite in the welded zone of 9% Cr/CrMoV dissimilar welded joint were observed by color metallographic method. Moreover, the details of the distribution, shape, length, length-to-width ratio, and the content of residual austenite in each welding layer were systematically characterized using Image-Pro Plus image analysis software. Different from the techniques such as X-ray diffraction, vibrating sample magnetometer, and electron backscatter diffraction that only involve the content of residual austenite, color metallographic method can offer much more details of the residual austenite, including the location, shape, size, and content, helping evaluate the overall characteristics of the residual austenite produced in the weld. It is interesting that a large amount of block-like and film-like residual austenite was found in the root of each welding layer, while rare at the top. The area fraction of residual austenite located in this zone was approximately 7.5% compared with only 0.5% at the top. In addition, the average area, length, and length-to-width ratio of dispersed residual austenite were quantitatively evaluated to be （4.7 ± 0.6）μm2, （5.1 ±0.6） μm, and （1.1 ± 0.1） μm, respectively. This variety of residual austenite was resulted from the tempering effect by latter welding layer on the previous one and different cooling rates in these two regions during the welding process.展开更多
A new 3D velocity model of the crust and upper mantle in the southeastern （SE） margin of the Tibetan plateau was obtained by joint inversion of body- and sur- face-wave data. For the body-wave data, we used 7190 eve...A new 3D velocity model of the crust and upper mantle in the southeastern （SE） margin of the Tibetan plateau was obtained by joint inversion of body- and sur- face-wave data. For the body-wave data, we used 7190 events recorded by 102 stations in the SE margin of the Tibetan plateau. The surface-wave data consist of Rayleigh wave phase velocity dispersion curves obtained from ambient noise cross-correlation analysis recorded by a dense array in the SE margin of the Tibetan plateau. The joint inversion clearly improves the Vs model because it is constrained by both data types. The results show that at around 10 km depth there are two low-velocity anomalies embedded within three high-velocity bodies along the Longmenshan fault system. These high-velocity bodies correspond well with the Precambrian massifs, and the two located to the northeast of 2013 Ms 7.0 Lushan earthquake are associated with high fault slip areas during the 2008 Wenchuan earthquake. The aftershock gap between 2013 Lushan earthquake and 2008 Wenchuan earthquake is associated with low-velocity anomalies, which also acts as a barrier zone for ruptures of two earthquakes. Generally large earthquakes （M 〉 5） in the region occurring from 2008 to 2015 are located around the high-velocity zones, indicating that they may act as asperities for these large earthquakes. Joint inversion results also clearly show that there exist low-velocity or weak zones in the mid-lower crust, which are not evenly distributed beneath the SE margin of Tibetan plateau.展开更多
High chromium （9-12% Cr） steels with excellent heat resistance and CrMoV steels with good toughness were potential candidates for combined rotor for steam turbine operated over 620℃. Two welding techniques were use...High chromium （9-12% Cr） steels with excellent heat resistance and CrMoV steels with good toughness were potential candidates for combined rotor for steam turbine operated over 620℃. Two welding techniques were used to fabricate 9% Cr and CrMoV dissimilar welded joint. The results show that the carbon migration only appears in the specimen using narrow gap submerged arc welding （NG-SAW） technique, yet it can be effectively prevented by adding tungsten inert gas （TlG） overlaying process before the NG-SAW. The carbon migration occurred in NG-SAW resulting from the sharp transition of the strong carbide-forming element Cr between the weld （-2.7 wt%） and the base metal （- 9 wt%）. On the contrary, the application of TIG overlaying layers can promote the diffusion of Cr element, and therefore result in its much smaller concentration gradient. That is to say, a gentle transition zone of Cr element can be created among the SAW weld, TIG overlaying layers and the base metal, which effectively prevents the carbon migration and therefore produces a decreased carbon concentration adjacent to the fusion line.展开更多
文摘There are often many chemicals coexisting in aquatic ecosystems, and few information on the joint toxicity of a mixture of organic pollutants is available at present. The 48-h toxicity of substituted phenols and anilines and their binary mixtures to Scenedesmus obliquus was determined by the algae inhibition test. The median effective inhibition concentration EC50 values for single compounds and EC50mix values for coexistent compounds were obtained. The n-octanol/water partition coefficient （logPmlx） and the frontier orbital energy gap （AEmlx） for mixtures were calculated. The following two-descriptor quantitative structure-activity relationships （QSARs） models were developed to predict single toxicity and joint toxicity respectively： log（1/ECs0） = 0.445logP - 0.801AE ＋ 9.501 （r2 = 0.876） and log （1/EC50mix） = 0.338logPmix- 0.492AEmix ＋ 6.928 （r^2 = 0.831）. The two equations were found to fit well. In addition, the model derived from the structural parameters of single components in binary mixtures log（1/EC50mix） = 0.2221ogP - 0.277AE ＋ 5.250 （r^2 = 0.879） can be used successfully to predict the toxicity of a mixture.
文摘The morphology and distribution of residual austenite in the welded zone of 9% Cr/CrMoV dissimilar welded joint were observed by color metallographic method. Moreover, the details of the distribution, shape, length, length-to-width ratio, and the content of residual austenite in each welding layer were systematically characterized using Image-Pro Plus image analysis software. Different from the techniques such as X-ray diffraction, vibrating sample magnetometer, and electron backscatter diffraction that only involve the content of residual austenite, color metallographic method can offer much more details of the residual austenite, including the location, shape, size, and content, helping evaluate the overall characteristics of the residual austenite produced in the weld. It is interesting that a large amount of block-like and film-like residual austenite was found in the root of each welding layer, while rare at the top. The area fraction of residual austenite located in this zone was approximately 7.5% compared with only 0.5% at the top. In addition, the average area, length, and length-to-width ratio of dispersed residual austenite were quantitatively evaluated to be （4.7 ± 0.6）μm2, （5.1 ±0.6） μm, and （1.1 ± 0.1） μm, respectively. This variety of residual austenite was resulted from the tempering effect by latter welding layer on the previous one and different cooling rates in these two regions during the welding process.
基金supported by the Natural National Science Foundation of China under grant number 41474039China National Special Fund for Earthquake Scientific Research in Public Interest under grant number 2016 CESE 0201+1 种基金Shanghai Committee of Science and Technology under grant number 14231202600the Fundamental Research Funds for the Central Universities under grant number WK2080000053
文摘A new 3D velocity model of the crust and upper mantle in the southeastern （SE） margin of the Tibetan plateau was obtained by joint inversion of body- and sur- face-wave data. For the body-wave data, we used 7190 events recorded by 102 stations in the SE margin of the Tibetan plateau. The surface-wave data consist of Rayleigh wave phase velocity dispersion curves obtained from ambient noise cross-correlation analysis recorded by a dense array in the SE margin of the Tibetan plateau. The joint inversion clearly improves the Vs model because it is constrained by both data types. The results show that at around 10 km depth there are two low-velocity anomalies embedded within three high-velocity bodies along the Longmenshan fault system. These high-velocity bodies correspond well with the Precambrian massifs, and the two located to the northeast of 2013 Ms 7.0 Lushan earthquake are associated with high fault slip areas during the 2008 Wenchuan earthquake. The aftershock gap between 2013 Lushan earthquake and 2008 Wenchuan earthquake is associated with low-velocity anomalies, which also acts as a barrier zone for ruptures of two earthquakes. Generally large earthquakes （M 〉 5） in the region occurring from 2008 to 2015 are located around the high-velocity zones, indicating that they may act as asperities for these large earthquakes. Joint inversion results also clearly show that there exist low-velocity or weak zones in the mid-lower crust, which are not evenly distributed beneath the SE margin of Tibetan plateau.
文摘High chromium （9-12% Cr） steels with excellent heat resistance and CrMoV steels with good toughness were potential candidates for combined rotor for steam turbine operated over 620℃. Two welding techniques were used to fabricate 9% Cr and CrMoV dissimilar welded joint. The results show that the carbon migration only appears in the specimen using narrow gap submerged arc welding （NG-SAW） technique, yet it can be effectively prevented by adding tungsten inert gas （TlG） overlaying process before the NG-SAW. The carbon migration occurred in NG-SAW resulting from the sharp transition of the strong carbide-forming element Cr between the weld （-2.7 wt%） and the base metal （- 9 wt%）. On the contrary, the application of TIG overlaying layers can promote the diffusion of Cr element, and therefore result in its much smaller concentration gradient. That is to say, a gentle transition zone of Cr element can be created among the SAW weld, TIG overlaying layers and the base metal, which effectively prevents the carbon migration and therefore produces a decreased carbon concentration adjacent to the fusion line.
