The ameliorative effect of external Ca^2＋ on Jerusalem artichoke （Helianthus tuberosus L.） under salt stress was studied through biochemical and physiological analyses of Jerusalem artichoke seedlings treated with ...The ameliorative effect of external Ca^2＋ on Jerusalem artichoke （Helianthus tuberosus L.） under salt stress was studied through biochemical and physiological analyses of Jerusalem artichoke seedlings treated with or without 10 mol L^-1 CaCl2, 150 mmol L^-1 NaCl, and/or 5 mmol L^-1 ethylene-bis（oxyethylenenitrilo）-tetraacetic acid （EGTA） for five days. Exposure to NaC1 （150 mmol L^-1） decreased growth, leaf chlorophyll content, and photosynthetic rate of Jerusalem artichoke seedlings. NaC1 treatment showed 59% and 37% higher lipid peroxidation and electrolyte leakage, respectively, than the control. The activities of superoxide dismutase （SOD）, peroxidase （POD）, and catalase （CAT） were decreased by NaCl, indicating an impeded antioxidant defense mechanism of Jerusalem artichoke grown under salt stress. Addition of 10 mmol L^-1 CaCl2 to the salt solutions significantly decreased the damaging effect of NaC1 on growth and chlorophyll content and simultaneously restored the rate of photosynthesis almost to the level of the control. Ca^2＋ addition decreased the leaf malondialdehyde （MDA） content and electrolyte leakage from NaCl-treated seedlings by 47% and 24%, respectively, and significantly improved the activities of SOD, POD, and CAT in NaCl-treated plants. Addition of EGTA, a specific chelator of Ca2＋, decreased the growth, chlorophyll content, and photosynthesis, and increased level of MDA and electrolyte leakage from NaCl-treated plants and from the control plants. EGTA addition to the growth medium also repressed the activities of SOD, POD, and CAT in NaCl-treated and control seedlings. External Ca2＋ might protect Jerusalem artichoke against NaC1 stress by up-regulating the activities of antioxidant enzymes and thereby decreasing the oxidative stress.展开更多
The railway tunnel concrete lining exposed to sulfate-bearing groundwater beyond 40 years in southwest of China was investigated. Field investigation, sulfate ions content and corroded products analysis, macro/microsc...The railway tunnel concrete lining exposed to sulfate-bearing groundwater beyond 40 years in southwest of China was investigated. Field investigation, sulfate ions content and corroded products analysis, macro/microscopic test were carried out. Results show that under the tunnel concrete lining structure and its served environmental conditions, sulfate solutions permeate concrete lining and accumulate on windward-side of concrete lining, resulting in the increase of sulfate ions content on windward-side and the diffusion of sulfate ions from windward-side to waterward-side, which cause the concrete lining of windward-side damaged seriously but the waterward-side of concrete lining is still in perfect condition. It is confirmed that structural characteristic of tunnel and environmental conditions lead to physical attack with the leaching of concrete and sodium sulfate crystallization as well as chemical corrosion with formation of gypsum in high sulfate concentration and formation of thaumasite in proper temperature rather than formation of ettringite. These achievements can provide academic and technical supports for understanding the deterioration mechanism of concrete lining as well as constructing railway tunnel under sulfate attack.展开更多
Controllable syntheses of different-sized gold nanoclusters are of great significance for their fundamental science and practical applications. In this work, we achieve the controllable and selective syntheses of Au7 ...Controllable syntheses of different-sized gold nanoclusters are of great significance for their fundamental science and practical applications. In this work, we achieve the controllable and selective syntheses of Au7 and Au13 clusters through adding HCl to the traditional Aull synthetic route at different reaction time. Time-dependent mass spectra and UV- Vis spectra were ernployed to monitor these two HCl-directed processes, and revealed the distinct roles of HCl as an etchant or a growth prornotor, respectively. Furthermore, parallel experiments on independent synthetic routes involving only non-chlorine H＋ （acetic acid） or Cl （tetraethy larnrnoniurn chloride） instead of HCl were perforrned, which illustrated the main role of H^＋-etching and Cl^ -assisted growth in HCl-directed cluster synthetic routes. We propose the HCl-etching is mainly achieved via the H＋ action to break the Au（I）-PPh3 part of clusters, while the HCl-prornoted growth is realized via the attachment of Au-Cl species to the pre-forrned clusters.展开更多
A spiro-type quaternary ammonium salt, spiro-(1,1′)-bipyrrolidinium tetrafluoroborate(SBP-BF4) was successfully prepared by an economical and efficient three-step process comprising the cyclization reaction of 1,4-di...A spiro-type quaternary ammonium salt, spiro-(1,1′)-bipyrrolidinium tetrafluoroborate(SBP-BF4) was successfully prepared by an economical and efficient three-step process comprising the cyclization reaction of 1,4-dibromobutane and pyrrolidine, and subsequent ion exchange pathway with KOH followed by neutralization reaction via HBF4 in the system of ethanol solution. 1H NMR, 13 C NMR, FI-IR and XPS analyses showed the structure of SBP-BF4. The as-obtained SBP-BF4 was dissolved in AN and used as the electrolyte for supercapacitor. Electrochemical measurements demonstrate that, compared with commercial electrolyte TEMA-BF4/AN, SBP-BF4/AN exhibits high ionic conductivity, lower resistance and improved cycling performance, which is due to its smaller ion size and stable symmetry structure.展开更多
A type of waveguide ring resonator, based on Er3+/Yb3+ co-doped phosphate glass and using thermal-optical effect as tuning manner, is brought up. The ring resonator is composed of two straight waveguides and a ring wa...A type of waveguide ring resonator, based on Er3+/Yb3+ co-doped phosphate glass and using thermal-optical effect as tuning manner, is brought up. The ring resonator is composed of two straight waveguides and a ring waveguide with radius of 400 μm. Electrode is evaporated on the top of the waveguide to achieve thermal tuning. Firstly, the filtering scheme of the ring resonator is analyzed, then how parameters of the electrode influence the filtering characteristics is discussed.展开更多
For the sake of understanding the deterioration behavior of concrete in actual railway tunnel structures subjected to aggressive sulfate medium in practice,detailed field investigations and tested analysis on sprayed ...For the sake of understanding the deterioration behavior of concrete in actual railway tunnel structures subjected to aggressive sulfate medium in practice,detailed field investigations and tested analysis on sprayed concrete linings of approximately 40-year-old railway tunnels in environments containing sulfate ion were carried out,respectively.The results show that the deterioration of concretes in the investigated area is serious,which involves complicated physicochemical process between the sulfate salt and concrete.Among them,the secondary sulfateminerals such as gypsum formation under very high concentration sulfate ion condition by accumulating and evaporation process dominate,followed by the crystallization of sulfate salt and formation of thaumasite.展开更多
The nanoparticles of Co1＋xMnxFe2-xO4 （0≤x ≤ 0.5） ferrite system are synthesized by solid-state reaction route using planetary ball milling technique to investigate structural, electrical and magnetic properties. ...The nanoparticles of Co1＋xMnxFe2-xO4 （0≤x ≤ 0.5） ferrite system are synthesized by solid-state reaction route using planetary ball milling technique to investigate structural, electrical and magnetic properties. The X-ray diffraction patterns confirm the inverse spinel structure with residual oxide phases. Three distinct regions of frequency response on dielectric constant are observed Co1.2sMn0.5Fe1.75O4 as determined by the Wayne Kerr Impedance Analyzer. The first two regions of frequency response 1.13-4.5 MHz and 4.5-6.5 MHz exhibit the normal behavior but the last region 6.5-10.5 MHz indicates its anomalous behavior due to concurrent contribution of O^2-, Fe^3＋, Co^2＋ and Mn^3＋ ions in the relaxation process for sintering effects （sintered at 700℃）. This anomalous behavior is found to be pronounced and significant for the sample of composition Co1.25Mn0.25Fe1.75O4, which may be suitable to be used in the frequency band filter over wide range of frequencies. The single peak of imaginary part of dielectric constant （ε＂） indicates that the conduction process in this sample is due to the grain boundary resistance. The pronounced increase of capacitance （C） as observed from 100 ℃ to 125 ~C in temperature dependent measurement （30-125℃） is expected to eause from the change of polarization across the grain boundary due to redistribution of ions by the thermal agitation. The variation of resistance （R） with temperature （30-125 ℃） is found to exhibit semieonducting behavior that resulted from the p-type carriers （Co^2＋/Co^3＋）. A significant increase of Z from 105 ℃ with the increase of temperature indicates the signature of phase transition from ferrimagnetic-to-ferromagnetic, which may be ascribed to the increase of Co content. The appearance of the single semicircular arc in the Cole-Cole plot may be attributed to the contribution of grain boundary resistance and correspond to the parallel equivalent circuit of resistor-capacitor （R-C） combination with single relaxation time. Saturation magnetization of Co1.25Mn0.25Fe1.75O4 and Co1.375Mn0.375Fe1.625O4 is found to be greater than the literature value （61.5 emu/g） of un-doped cobalt ferrite in the measurement of their initial magnetization using Lakeshore vibrating sample magnetometer. The negative real part of AC permeability of Co1.5Mn0.5Fe1.5O4 signifies the diamagnetic behavior in the frequency range 0.13-25.2 MHz and expected to cause from the formation of magnetic dipoles opposite to the applied field due to Mn^2＋ in the B site. The samples are expected to be suitable for dielectric heating and high frequency applications.展开更多
In this paper, we characterize the North Yellow Sea （NYS） water masses in summer by analyzing temperature and salinity data surveyed in 2006. The Liaonan Coastal Water is characterized by low salinity westward and s...In this paper, we characterize the North Yellow Sea （NYS） water masses in summer by analyzing temperature and salinity data surveyed in 2006. The Liaonan Coastal Water is characterized by low salinity westward and southward flow paths. The westward path flows parallel to land, turns to the south, then to the southeast adjacent to the mouth of the Lushun River, where it mixes with other coastal water directly to the southwest. It becomes the main source of low salinity water in the deep water area west of 123°E. The high-salinity Lubei Coastal Water is the remnant of the winter Lubei Coastal Water, which is located mostly in a small area between Yantai and Weihai, and does not originate in the Bohai Sea Coastal Water. The two NYS zones demarcated at 123°E have distinctly different temperature and salinity characteristics. There are two high-salinity centers east of 123°E, whereas there is low-salinity water to the west whose temperature and salinity structures are complex, composed of the coastal water south of Chengshantou, the Liaonan Coastal Water and the Bohai Sea Water.展开更多
There are a series of special mountain soils on the Tibetan Plateau of China in an alpine environment for the high altitude. However, very few studies have focused on major soil elements in relation to soil formation ...There are a series of special mountain soils on the Tibetan Plateau of China in an alpine environment for the high altitude. However, very few studies have focused on major soil elements in relation to soil formation in this area. Aluminum （Al）, iron （Fe）, calcium （Ca）, sodium （Na）, potassium （K） and magnesium （Mg） contents of 237 topsoil samples covering a 2.8-km altitudinal gradient in uncultivated areas along the Qinghai-Tibet Railway of China were measured using inductively coupled plasma atomic emission spectroscopy. The spatial distribution of the elements and its relationship to the parent rocks and climatic parameters were analyzed. Soils along the gradient are derived from a range of parent materials, but most are less than 30 cm deep with little development （Cambisols）. Soil Al, Fe and Mg contents showed a decreasing trend from the start station （Xining Station） to end station （Lhasa Station） of the Qinghai-Tibet Railway, whereas soil K and Na contents were relative stable from Xining Station to the Kunlun Mountains and then increased gradually. Soil Ca content was lower in the southern part of the Tanggula Mountains. The major soil element contents clearly reflected the parent rock and climatic influences. Soils with higher Ca content appeared in areas with Ca-Mg carbonate rocks, soils with higher Al were found in areas with silicate-rich and high-Al silicate clastic rocks and silicate-rich aluminosilicate loose sediments. Soils with higher K and Na contents appeared in areas with high-K, high-Na and silicate-rich aluminosilicate rocks. Soil Na and K contents were affected by temperature, whereas the contents of Mg, Fe, Ca and Al were more affected by precipitation. Soil Na and K contents increased with increasing temperatures, whereas the contents of Mg, Fe, Ca and Al decreased with increasing precipitation. This analysis provides a relationship between soil properties and rapidly changing environmental conditions. The data can be used to investigate the effect of the climate or land use change on soil properties.展开更多
基金the National High Technology Research and Development Program of China (863 Program)(No. 2003AA627040).
文摘The ameliorative effect of external Ca^2＋ on Jerusalem artichoke （Helianthus tuberosus L.） under salt stress was studied through biochemical and physiological analyses of Jerusalem artichoke seedlings treated with or without 10 mol L^-1 CaCl2, 150 mmol L^-1 NaCl, and/or 5 mmol L^-1 ethylene-bis（oxyethylenenitrilo）-tetraacetic acid （EGTA） for five days. Exposure to NaC1 （150 mmol L^-1） decreased growth, leaf chlorophyll content, and photosynthetic rate of Jerusalem artichoke seedlings. NaC1 treatment showed 59% and 37% higher lipid peroxidation and electrolyte leakage, respectively, than the control. The activities of superoxide dismutase （SOD）, peroxidase （POD）, and catalase （CAT） were decreased by NaCl, indicating an impeded antioxidant defense mechanism of Jerusalem artichoke grown under salt stress. Addition of 10 mmol L^-1 CaCl2 to the salt solutions significantly decreased the damaging effect of NaC1 on growth and chlorophyll content and simultaneously restored the rate of photosynthesis almost to the level of the control. Ca^2＋ addition decreased the leaf malondialdehyde （MDA） content and electrolyte leakage from NaCl-treated seedlings by 47% and 24%, respectively, and significantly improved the activities of SOD, POD, and CAT in NaCl-treated plants. Addition of EGTA, a specific chelator of Ca2＋, decreased the growth, chlorophyll content, and photosynthesis, and increased level of MDA and electrolyte leakage from NaCl-treated plants and from the control plants. EGTA addition to the growth medium also repressed the activities of SOD, POD, and CAT in NaCl-treated and control seedlings. External Ca2＋ might protect Jerusalem artichoke against NaC1 stress by up-regulating the activities of antioxidant enzymes and thereby decreasing the oxidative stress.
基金Project(51108463) supported by the National Natural Science Foundation of ChinaProject(11B041) supported by Scientific Research Fund of Hunan Provincial Education Department of ChinaProject(NCET-10-0839) supported by Ministry Education of China
文摘The railway tunnel concrete lining exposed to sulfate-bearing groundwater beyond 40 years in southwest of China was investigated. Field investigation, sulfate ions content and corroded products analysis, macro/microscopic test were carried out. Results show that under the tunnel concrete lining structure and its served environmental conditions, sulfate solutions permeate concrete lining and accumulate on windward-side of concrete lining, resulting in the increase of sulfate ions content on windward-side and the diffusion of sulfate ions from windward-side to waterward-side, which cause the concrete lining of windward-side damaged seriously but the waterward-side of concrete lining is still in perfect condition. It is confirmed that structural characteristic of tunnel and environmental conditions lead to physical attack with the leaching of concrete and sodium sulfate crystallization as well as chemical corrosion with formation of gypsum in high sulfate concentration and formation of thaumasite in proper temperature rather than formation of ettringite. These achievements can provide academic and technical supports for understanding the deterioration mechanism of concrete lining as well as constructing railway tunnel under sulfate attack.
基金supported by the National Natural Science Foundation of China (No.11475176, No.U1632263, and No.21533007)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No.11621063)
文摘Controllable syntheses of different-sized gold nanoclusters are of great significance for their fundamental science and practical applications. In this work, we achieve the controllable and selective syntheses of Au7 and Au13 clusters through adding HCl to the traditional Aull synthetic route at different reaction time. Time-dependent mass spectra and UV- Vis spectra were ernployed to monitor these two HCl-directed processes, and revealed the distinct roles of HCl as an etchant or a growth prornotor, respectively. Furthermore, parallel experiments on independent synthetic routes involving only non-chlorine H＋ （acetic acid） or Cl （tetraethy larnrnoniurn chloride） instead of HCl were perforrned, which illustrated the main role of H^＋-etching and Cl^ -assisted growth in HCl-directed cluster synthetic routes. We propose the HCl-etching is mainly achieved via the H＋ action to break the Au（I）-PPh3 part of clusters, while the HCl-prornoted growth is realized via the attachment of Au-Cl species to the pre-forrned clusters.
基金Project(51371198)supported by the National Natural Science Foundation of China
文摘A spiro-type quaternary ammonium salt, spiro-(1,1′)-bipyrrolidinium tetrafluoroborate(SBP-BF4) was successfully prepared by an economical and efficient three-step process comprising the cyclization reaction of 1,4-dibromobutane and pyrrolidine, and subsequent ion exchange pathway with KOH followed by neutralization reaction via HBF4 in the system of ethanol solution. 1H NMR, 13 C NMR, FI-IR and XPS analyses showed the structure of SBP-BF4. The as-obtained SBP-BF4 was dissolved in AN and used as the electrolyte for supercapacitor. Electrochemical measurements demonstrate that, compared with commercial electrolyte TEMA-BF4/AN, SBP-BF4/AN exhibits high ionic conductivity, lower resistance and improved cycling performance, which is due to its smaller ion size and stable symmetry structure.
基金National Nature Science Foundation of China(60377021)Key Laboratory Foundation of National Defence(51472040205DZ0201)
文摘A type of waveguide ring resonator, based on Er3+/Yb3+ co-doped phosphate glass and using thermal-optical effect as tuning manner, is brought up. The ring resonator is composed of two straight waveguides and a ring waveguide with radius of 400 μm. Electrode is evaporated on the top of the waveguide to achieve thermal tuning. Firstly, the filtering scheme of the ring resonator is analyzed, then how parameters of the electrode influence the filtering characteristics is discussed.
基金Project(2008G025-C) supported by the Ministry of Railway of ChinaProject(50708114) supported by the National Natural Science Foundation of China
文摘For the sake of understanding the deterioration behavior of concrete in actual railway tunnel structures subjected to aggressive sulfate medium in practice,detailed field investigations and tested analysis on sprayed concrete linings of approximately 40-year-old railway tunnels in environments containing sulfate ion were carried out,respectively.The results show that the deterioration of concretes in the investigated area is serious,which involves complicated physicochemical process between the sulfate salt and concrete.Among them,the secondary sulfateminerals such as gypsum formation under very high concentration sulfate ion condition by accumulating and evaporation process dominate,followed by the crystallization of sulfate salt and formation of thaumasite.
文摘The nanoparticles of Co1＋xMnxFe2-xO4 （0≤x ≤ 0.5） ferrite system are synthesized by solid-state reaction route using planetary ball milling technique to investigate structural, electrical and magnetic properties. The X-ray diffraction patterns confirm the inverse spinel structure with residual oxide phases. Three distinct regions of frequency response on dielectric constant are observed Co1.2sMn0.5Fe1.75O4 as determined by the Wayne Kerr Impedance Analyzer. The first two regions of frequency response 1.13-4.5 MHz and 4.5-6.5 MHz exhibit the normal behavior but the last region 6.5-10.5 MHz indicates its anomalous behavior due to concurrent contribution of O^2-, Fe^3＋, Co^2＋ and Mn^3＋ ions in the relaxation process for sintering effects （sintered at 700℃）. This anomalous behavior is found to be pronounced and significant for the sample of composition Co1.25Mn0.25Fe1.75O4, which may be suitable to be used in the frequency band filter over wide range of frequencies. The single peak of imaginary part of dielectric constant （ε＂） indicates that the conduction process in this sample is due to the grain boundary resistance. The pronounced increase of capacitance （C） as observed from 100 ℃ to 125 ~C in temperature dependent measurement （30-125℃） is expected to eause from the change of polarization across the grain boundary due to redistribution of ions by the thermal agitation. The variation of resistance （R） with temperature （30-125 ℃） is found to exhibit semieonducting behavior that resulted from the p-type carriers （Co^2＋/Co^3＋）. A significant increase of Z from 105 ℃ with the increase of temperature indicates the signature of phase transition from ferrimagnetic-to-ferromagnetic, which may be ascribed to the increase of Co content. The appearance of the single semicircular arc in the Cole-Cole plot may be attributed to the contribution of grain boundary resistance and correspond to the parallel equivalent circuit of resistor-capacitor （R-C） combination with single relaxation time. Saturation magnetization of Co1.25Mn0.25Fe1.75O4 and Co1.375Mn0.375Fe1.625O4 is found to be greater than the literature value （61.5 emu/g） of un-doped cobalt ferrite in the measurement of their initial magnetization using Lakeshore vibrating sample magnetometer. The negative real part of AC permeability of Co1.5Mn0.5Fe1.5O4 signifies the diamagnetic behavior in the frequency range 0.13-25.2 MHz and expected to cause from the formation of magnetic dipoles opposite to the applied field due to Mn^2＋ in the B site. The samples are expected to be suitable for dielectric heating and high frequency applications.
基金Supported by China’s National 908 Program (Nos. 908-01-ST02,908-02-02-02 908-02-02-03)+2 种基金National Natural Science Foundation of China (No. 40976001)National Basic Research Priorities Program (No. 2005CB422308)National High Technology Research and Development Program (863 Program,No. 2007AA092104)
文摘In this paper, we characterize the North Yellow Sea （NYS） water masses in summer by analyzing temperature and salinity data surveyed in 2006. The Liaonan Coastal Water is characterized by low salinity westward and southward flow paths. The westward path flows parallel to land, turns to the south, then to the southeast adjacent to the mouth of the Lushun River, where it mixes with other coastal water directly to the southwest. It becomes the main source of low salinity water in the deep water area west of 123°E. The high-salinity Lubei Coastal Water is the remnant of the winter Lubei Coastal Water, which is located mostly in a small area between Yantai and Weihai, and does not originate in the Bohai Sea Coastal Water. The two NYS zones demarcated at 123°E have distinctly different temperature and salinity characteristics. There are two high-salinity centers east of 123°E, whereas there is low-salinity water to the west whose temperature and salinity structures are complex, composed of the coastal water south of Chengshantou, the Liaonan Coastal Water and the Bohai Sea Water.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (No.XDB03030500)the National Key Technology Research and Development Program of China (No.2013BAC04B02)the National Natural Science Foundation of China (Nos.40801042 and 90202012)
文摘There are a series of special mountain soils on the Tibetan Plateau of China in an alpine environment for the high altitude. However, very few studies have focused on major soil elements in relation to soil formation in this area. Aluminum （Al）, iron （Fe）, calcium （Ca）, sodium （Na）, potassium （K） and magnesium （Mg） contents of 237 topsoil samples covering a 2.8-km altitudinal gradient in uncultivated areas along the Qinghai-Tibet Railway of China were measured using inductively coupled plasma atomic emission spectroscopy. The spatial distribution of the elements and its relationship to the parent rocks and climatic parameters were analyzed. Soils along the gradient are derived from a range of parent materials, but most are less than 30 cm deep with little development （Cambisols）. Soil Al, Fe and Mg contents showed a decreasing trend from the start station （Xining Station） to end station （Lhasa Station） of the Qinghai-Tibet Railway, whereas soil K and Na contents were relative stable from Xining Station to the Kunlun Mountains and then increased gradually. Soil Ca content was lower in the southern part of the Tanggula Mountains. The major soil element contents clearly reflected the parent rock and climatic influences. Soils with higher Ca content appeared in areas with Ca-Mg carbonate rocks, soils with higher Al were found in areas with silicate-rich and high-Al silicate clastic rocks and silicate-rich aluminosilicate loose sediments. Soils with higher K and Na contents appeared in areas with high-K, high-Na and silicate-rich aluminosilicate rocks. Soil Na and K contents were affected by temperature, whereas the contents of Mg, Fe, Ca and Al were more affected by precipitation. Soil Na and K contents increased with increasing temperatures, whereas the contents of Mg, Fe, Ca and Al decreased with increasing precipitation. This analysis provides a relationship between soil properties and rapidly changing environmental conditions. The data can be used to investigate the effect of the climate or land use change on soil properties.
