The physical-mechanical properties of Populus x canadensis Moench and Populus x euramericana （Dode） Guinier cv. Gelrica were studied to provide theoret- ical and scientific bases for the directional breeding and eff...The physical-mechanical properties of Populus x canadensis Moench and Populus x euramericana （Dode） Guinier cv. Gelrica were studied to provide theoret- ical and scientific bases for the directional breeding and efficient use of artificial forests with P. canadensis and P. euramericana Gelrica. The results showed the air-dried density, basic density of P. canadensis were 0.468 g/cm3 and 0.372 g/cm3, respectively; the shrinkage coefficient of radial, tangential and volume were 0.133%, 0.270% and 0.553%, respectively;the modulus of elasticity in static bending, the bending strength and the compressive strength parallel to grain were 9 302.99 MPa, 79.69 MPa and 40.32 Mpa, respectively. As for the P. euramericana Gelrica, the air-dried density, basic densitywere 0.453 and 0.355 g/cm3, respectively; the shrink- age coefficient of radial, tangential and volume were 0.205%, 0.304% and 0.554%, respectively; the modulus of elasticity in static bending, the bending strength and the compressive strength parallel to grain were 9 014.44, 55.87 and 33.09 Mpa respectively. Comprehensive analysis of the indicators showed that the properties of P. canadensis were better than those of P.euramericana Gelrica.展开更多
A novel diarylheptanoid, named Jugcathanin（1）, along with two known diarylheptanoids（2,3）, were isolated from the fresh pericarps ofduglans Cathayensis Dode. A known triterpene（4） and a known aphthaoquinone（5）...A novel diarylheptanoid, named Jugcathanin（1）, along with two known diarylheptanoids（2,3）, were isolated from the fresh pericarps ofduglans Cathayensis Dode. A known triterpene（4） and a known aphthaoquinone（5） were also isolated from the plant. Their structures were elucidated on the basis of spectroscopic studies. All the compounds exhibited moderate cytotoxicities against human Hela, HepG2, and HL-60 cell lines.展开更多
Soil respiration from decomposing aboveground litter is a major component of the terrestrial carbon cycle. However, variations in the contribution of aboveground litter to the total soil respiration for stands of vary...Soil respiration from decomposing aboveground litter is a major component of the terrestrial carbon cycle. However, variations in the contribution of aboveground litter to the total soil respiration for stands of varying ages are poorly understood. To assess soil respiration induced by aboveground litter, treatments of litter and no litter were applied to 5-, l0-, and 20-year-old stands of Populus davidiana Dode in the sandstorm source area of Beijing-Tianjin, equations were applied to China. Optimal nonlinear model the combined effects of soil temperature and soil water content on soil respiration. Results showed that the monthly average contribution of aboveground litter to total soil respiration were 18.46% ± 4.63%, 16.64% ± 9.31%, and 22.37% ± 8.17% for 5-, 10-, and ao-year-old stands, respectively. The relatively high contribution in 5- and 20-year-old stands could be attributed to easily decomposition products and high accumulated litter, resoectivelv. Also. it fluctuated monthly for all stand ages due to substrate availability caused by phenology and environmental factors. Litter removal significantly decreased soil respiration and soil water content for all stand ages （P 〈 0.05） but not soil temperature （P 〉 0.05）. Variations of soil respiration could be explained by soil temperature at 5-cm depth using an exponential equation and by soil water content at lo-cm depth using a quadratic equation, whereas soil respiration was better modeled using the combined parameters of soil temperature and soil water content than with either soil temperature or soil water content alone. Temperature sensitivity （Q10） increased with stand age in both the litter and the no litter treatments. Considering the effects of aboveground litter, this study provides insights for predicting future soil carbon fluxes and for accurately assessing soil carbon budgets.展开更多
The root segments selected from dominant trees of Populus davidiana Dode were taken as reproductive material and were buried in different depths to carry out the reproduction of root turion sprout. The affecting facto...The root segments selected from dominant trees of Populus davidiana Dode were taken as reproductive material and were buried in different depths to carry out the reproduction of root turion sprout. The affecting factors of germination rate, survival rate, and height growth for cutting wood of root sprout were comparatively analyzed. The results showed that the best suitable substrate for burying root is pearlite, with a germination rate of 15.16%. 3-4-cm root segments has the highest rate of germination (12.4%). The mixture of sand and soil (2:1) is the best cutting substrate, with a survival rate of 81.3%, while as to height growth of cutting wood, the mixture of turfy and soil (1:1) is the best. The cutting woods selected from different positions of stem show difference in height growth. The cutting wood from top stem is higher obviously than those from middle or low stem.展开更多
Hollow calcium carbonate （ CaCO3 ） microspheres were prepared in aqueous solution with the presence of polyoxyethylene （20） sorbitan monolaurate （ Tween20 ） and sodium dodecyl sulfate （SDS）. The microspheres w...Hollow calcium carbonate （ CaCO3 ） microspheres were prepared in aqueous solution with the presence of polyoxyethylene （20） sorbitan monolaurate （ Tween20 ） and sodium dodecyl sulfate （SDS）. The microspheres were characterized with X-ray diffraction （XRD） , scanning electron microscopy （SEM） and transmission electron microscope （TEM）. The X-ray diffraction data showed that the hollow CaCO3 microsphere consisted of calcite crystals. The influence of Tween20 and SDS concentrations on the morphology of CaCO3 crystals was investigated. The results suggested that the ＂core-shell model＂ of Tween20/SDS micelle aggregated as templates, which could control the growth of hollow CaCO3 microspheres. The interaction between mixed surfactants and calcium ions played a critical role in organizing calcium carbonate in microscopic level.展开更多
文摘The physical-mechanical properties of Populus x canadensis Moench and Populus x euramericana （Dode） Guinier cv. Gelrica were studied to provide theoret- ical and scientific bases for the directional breeding and efficient use of artificial forests with P. canadensis and P. euramericana Gelrica. The results showed the air-dried density, basic density of P. canadensis were 0.468 g/cm3 and 0.372 g/cm3, respectively; the shrinkage coefficient of radial, tangential and volume were 0.133%, 0.270% and 0.553%, respectively;the modulus of elasticity in static bending, the bending strength and the compressive strength parallel to grain were 9 302.99 MPa, 79.69 MPa and 40.32 Mpa, respectively. As for the P. euramericana Gelrica, the air-dried density, basic densitywere 0.453 and 0.355 g/cm3, respectively; the shrink- age coefficient of radial, tangential and volume were 0.205%, 0.304% and 0.554%, respectively; the modulus of elasticity in static bending, the bending strength and the compressive strength parallel to grain were 9 014.44, 55.87 and 33.09 Mpa respectively. Comprehensive analysis of the indicators showed that the properties of P. canadensis were better than those of P.euramericana Gelrica.
基金the Natural Science Foundation of Hubei Province, China(No. 2006ABA125)
文摘A novel diarylheptanoid, named Jugcathanin（1）, along with two known diarylheptanoids（2,3）, were isolated from the fresh pericarps ofduglans Cathayensis Dode. A known triterpene（4） and a known aphthaoquinone（5） were also isolated from the plant. Their structures were elucidated on the basis of spectroscopic studies. All the compounds exhibited moderate cytotoxicities against human Hela, HepG2, and HL-60 cell lines.
基金funded by the National Natural Science Foundation of China (Grant No.31170414)the 100 Talents Program of Chinese Academy of Sciences,and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA05060600)
文摘Soil respiration from decomposing aboveground litter is a major component of the terrestrial carbon cycle. However, variations in the contribution of aboveground litter to the total soil respiration for stands of varying ages are poorly understood. To assess soil respiration induced by aboveground litter, treatments of litter and no litter were applied to 5-, l0-, and 20-year-old stands of Populus davidiana Dode in the sandstorm source area of Beijing-Tianjin, equations were applied to China. Optimal nonlinear model the combined effects of soil temperature and soil water content on soil respiration. Results showed that the monthly average contribution of aboveground litter to total soil respiration were 18.46% ± 4.63%, 16.64% ± 9.31%, and 22.37% ± 8.17% for 5-, 10-, and ao-year-old stands, respectively. The relatively high contribution in 5- and 20-year-old stands could be attributed to easily decomposition products and high accumulated litter, resoectivelv. Also. it fluctuated monthly for all stand ages due to substrate availability caused by phenology and environmental factors. Litter removal significantly decreased soil respiration and soil water content for all stand ages （P 〈 0.05） but not soil temperature （P 〉 0.05）. Variations of soil respiration could be explained by soil temperature at 5-cm depth using an exponential equation and by soil water content at lo-cm depth using a quadratic equation, whereas soil respiration was better modeled using the combined parameters of soil temperature and soil water content than with either soil temperature or soil water content alone. Temperature sensitivity （Q10） increased with stand age in both the litter and the no litter treatments. Considering the effects of aboveground litter, this study provides insights for predicting future soil carbon fluxes and for accurately assessing soil carbon budgets.
文摘The root segments selected from dominant trees of Populus davidiana Dode were taken as reproductive material and were buried in different depths to carry out the reproduction of root turion sprout. The affecting factors of germination rate, survival rate, and height growth for cutting wood of root sprout were comparatively analyzed. The results showed that the best suitable substrate for burying root is pearlite, with a germination rate of 15.16%. 3-4-cm root segments has the highest rate of germination (12.4%). The mixture of sand and soil (2:1) is the best cutting substrate, with a survival rate of 81.3%, while as to height growth of cutting wood, the mixture of turfy and soil (1:1) is the best. The cutting woods selected from different positions of stem show difference in height growth. The cutting wood from top stem is higher obviously than those from middle or low stem.
基金Supported by the Beijing Natural Science Foundation(2082021)the National Science & Technology Pillar Program in the 12th Five-Year Plan Period (2011BAE06B06-2)
文摘Hollow calcium carbonate （ CaCO3 ） microspheres were prepared in aqueous solution with the presence of polyoxyethylene （20） sorbitan monolaurate （ Tween20 ） and sodium dodecyl sulfate （SDS）. The microspheres were characterized with X-ray diffraction （XRD） , scanning electron microscopy （SEM） and transmission electron microscope （TEM）. The X-ray diffraction data showed that the hollow CaCO3 microsphere consisted of calcite crystals. The influence of Tween20 and SDS concentrations on the morphology of CaCO3 crystals was investigated. The results suggested that the ＂core-shell model＂ of Tween20/SDS micelle aggregated as templates, which could control the growth of hollow CaCO3 microspheres. The interaction between mixed surfactants and calcium ions played a critical role in organizing calcium carbonate in microscopic level.
