Surface coatings and surficial sediments were obtained in four natural waters in Xianghai Wetland in China to study the role of surface coatings and surficial sediments in controlling the transporting and cycling of h...Surface coatings and surficial sediments were obtained in four natural waters in Xianghai Wetland in China to study the role of surface coatings and surficial sediments in controlling the transporting and cycling of heavy metals in aquatic environments. Pb and Cd adsorption to the surface coatings and surficial sediments were measured under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0 05 mol/L, 25℃ and pH 6 0 for surface coatings; and 0 005 mol/L CaCl 2 solution, 25℃ and pH 6 0 for surficial sediments). The Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb and Cd adsorption to the surface coatings and surficial sediments, and the component analyses of surface coatings and surficial sediments were also carried out. Correlation analyses between the maximum adsorption of Pb and Cd(Г max ) and the components in the surface coatings and surficial sediments suggested that there was a statistically significant trend for Pb and Cd adsorption(Г max ) to the surface coatings to increase with increasing in contents of Fe and Mn oxides in the surface coatings and surficial sediments. And the metal adsorption abilities of surface coatings were much stronger than those of surficial sediments, highlighting that in the same water, i.e. at the same pH and initial metal concentrations, the metals(such as lead and cadmium) in supernatant were feasible to be adsorbed by surface coatings than surficial sediments. The more importance of surface coatings than surficial sediments for adsorbing and cycling of heavy metals in aquatic environments was evidenced.展开更多
The present study examined the effect of alkali extraction on pit membranes （PMs） and liquid uptake of four conifers. Af- ter alkali extraction, the deposits around the PMs almost dissolved in Cunninghamia lanceolat...The present study examined the effect of alkali extraction on pit membranes （PMs） and liquid uptake of four conifers. Af- ter alkali extraction, the deposits around the PMs almost dissolved in Cunninghamia lanceolata Hook. and Cryptomeriajaponica D. Don wood which showed good liquid uptake. In contrast, in Larix leptolepis Gordon and Pseudotsuga menziesii Franco, although the tori adhered strongly to the pit aperture preventing liquid transportation, the liquid uptake of the woods improved markedly. More- over, the combined treatment of alkali extraction-transverse compression had no synergistic effect in improving liquid uptake. These results demonstrate that alkali extraction is effective in improving the liquid uptake of wood.展开更多
The geometrical structures of 2 (2 hydroxyphenyl) pyridine(PP) and its protonation states were optimized by means of the B3LYP/6 31G(d) method. For all the selected systems, the existence of H bond is in favor of ...The geometrical structures of 2 (2 hydroxyphenyl) pyridine(PP) and its protonation states were optimized by means of the B3LYP/6 31G(d) method. For all the selected systems, the existence of H bond is in favor of the stability of the systems. On the basis of the optimized geometrical structures, their electronic spectrum properties were studied by time dependent density functional theory(TD DFT) methosd via a hybrid function of B3LYP and 6 31G(d) basis set. The TD DFT calculation result predicts the absorption spectrum of PP at 324 nm(3.82 eV), which is in very good agreement with the experimental value of 322 nm( 3.85 eV ) determined in solvent chloroform. The absorption spectra of the two protonation states both exert a red shift in various pH media.展开更多
Effects of Nd on the mechanical properties of die casting magnesium alloysAM50 are investigated. It is found that the ultimate tensile strength, yield strength and elongationof the AM50 alloy at elevated temperatures ...Effects of Nd on the mechanical properties of die casting magnesium alloysAM50 are investigated. It is found that the ultimate tensile strength, yield strength and elongationof the AM50 alloy at elevated temperatures up to 200 deg C increase with an addition of Nd.Generally, the most significant improvement in the tensile properties is attained at 100 deg C. Thepresence of Mg12Nd is proved by X-ray diffraction. Microstructural observations reveal that theaddition of Nd can lead to the dispersion-strengthening. Due to the presence of Mg12Nd, the slidingof grain boundaries is restrained and the strength of the alloy is enhanced. It can be seen from thetensile fractographs that the fracture surfaces exhibit the mixed fracture characteristics, andless brittle fracture is observed with increasing the temperature. Quasi-cleavage fracture isthought as the main fracture mode. TEM observations expose the formation of dislocation network,slip lines and dislocation pile-ups.展开更多
文摘Surface coatings and surficial sediments were obtained in four natural waters in Xianghai Wetland in China to study the role of surface coatings and surficial sediments in controlling the transporting and cycling of heavy metals in aquatic environments. Pb and Cd adsorption to the surface coatings and surficial sediments were measured under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0 05 mol/L, 25℃ and pH 6 0 for surface coatings; and 0 005 mol/L CaCl 2 solution, 25℃ and pH 6 0 for surficial sediments). The Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb and Cd adsorption to the surface coatings and surficial sediments, and the component analyses of surface coatings and surficial sediments were also carried out. Correlation analyses between the maximum adsorption of Pb and Cd(Г max ) and the components in the surface coatings and surficial sediments suggested that there was a statistically significant trend for Pb and Cd adsorption(Г max ) to the surface coatings to increase with increasing in contents of Fe and Mn oxides in the surface coatings and surficial sediments. And the metal adsorption abilities of surface coatings were much stronger than those of surficial sediments, highlighting that in the same water, i.e. at the same pH and initial metal concentrations, the metals(such as lead and cadmium) in supernatant were feasible to be adsorbed by surface coatings than surficial sediments. The more importance of surface coatings than surficial sediments for adsorbing and cycling of heavy metals in aquatic environments was evidenced.
基金supported by the Mission Project Fund,provided by the Center for Exploratory Research on Humanosphere,Research Institute for Sustainable Humanosphere,Kyoto University,Japan
文摘The present study examined the effect of alkali extraction on pit membranes （PMs） and liquid uptake of four conifers. Af- ter alkali extraction, the deposits around the PMs almost dissolved in Cunninghamia lanceolata Hook. and Cryptomeriajaponica D. Don wood which showed good liquid uptake. In contrast, in Larix leptolepis Gordon and Pseudotsuga menziesii Franco, although the tori adhered strongly to the pit aperture preventing liquid transportation, the liquid uptake of the woods improved markedly. More- over, the combined treatment of alkali extraction-transverse compression had no synergistic effect in improving liquid uptake. These results demonstrate that alkali extraction is effective in improving the liquid uptake of wood.
基金Supported by the Excellent Young Teachers Program of MOETrans- century Program me Foundation for the Talentsby the State Education Ministry and Excellent Youth Foundation of Jilin Province
文摘The geometrical structures of 2 (2 hydroxyphenyl) pyridine(PP) and its protonation states were optimized by means of the B3LYP/6 31G(d) method. For all the selected systems, the existence of H bond is in favor of the stability of the systems. On the basis of the optimized geometrical structures, their electronic spectrum properties were studied by time dependent density functional theory(TD DFT) methosd via a hybrid function of B3LYP and 6 31G(d) basis set. The TD DFT calculation result predicts the absorption spectrum of PP at 324 nm(3.82 eV), which is in very good agreement with the experimental value of 322 nm( 3.85 eV ) determined in solvent chloroform. The absorption spectra of the two protonation states both exert a red shift in various pH media.
基金This project is supported by Provincial Natural Science Foundation of Liaoning (No.002015)
文摘Effects of Nd on the mechanical properties of die casting magnesium alloysAM50 are investigated. It is found that the ultimate tensile strength, yield strength and elongationof the AM50 alloy at elevated temperatures up to 200 deg C increase with an addition of Nd.Generally, the most significant improvement in the tensile properties is attained at 100 deg C. Thepresence of Mg12Nd is proved by X-ray diffraction. Microstructural observations reveal that theaddition of Nd can lead to the dispersion-strengthening. Due to the presence of Mg12Nd, the slidingof grain boundaries is restrained and the strength of the alloy is enhanced. It can be seen from thetensile fractographs that the fracture surfaces exhibit the mixed fracture characteristics, andless brittle fracture is observed with increasing the temperature. Quasi-cleavage fracture isthought as the main fracture mode. TEM observations expose the formation of dislocation network,slip lines and dislocation pile-ups.
