[Objective] This study aimed to explore the relationship between different forest types and water conservation function. [Method] Based on field survey and experimental analysis, water conservation function of four ty...[Objective] This study aimed to explore the relationship between different forest types and water conservation function. [Method] Based on field survey and experimental analysis, water conservation function of four typical forest stands in Jinyun Mountain of Chongqing was explored, including conifer-broadleaved mixed for- est, evergreen broad-leaved forest, bamboo forest and shrub forest. [Result] The re- sults showed that the order of saturated water storage capacity of soil in four forest stands was shrub forest （266.48 mm） 〉 conifer-broadleaved mixed forest （190.40 mm） 〉 evergreen broad-leaved forest （186.80 mm） 〉 bamboo forest （174.80 mm）; the order of maximum water-holding capacity of litter was shrub forest （8.06 mm） 〉 conifer-broadleaved mixed forest （4.71 mm） 〉 evergreen broad-leaved forest （4.32 mm） 〉 bamboo forest （3.34 mm）; the order of canopy interception in various forest stands was conifer-broadleaved mixed forest （16.15%） 〉 evergreen broad-leaved for- est （14.70%） 〉 bamboo forest （12.64%）. [Conclusion] The study had great signifi- cance to rational manage forest resources, improve water environment and realize scientific management and use of water resources.展开更多
The three-dimensional structure of recombinant hepatitis B core antigen（HBcAg） particles truncated at residue 154（HBcAg-154） was determined to 7.8 A resolution by cryo-electron microscopy（cryoEM） and computer re...The three-dimensional structure of recombinant hepatitis B core antigen（HBcAg） particles truncated at residue 154（HBcAg-154） was determined to 7.8 A resolution by cryo-electron microscopy（cryoEM） and computer reconstruction.The capsid of HBcAg-154 is mainly constituted by α-helical folds,highly similar to that of HBcAg-149.The C-terminal region between residues 155 and 183 of the core protein is more crucial to the encapsidation of RNA,and the short C-terminal tail of HBcAg-154 results in a nearly empty capsid.展开更多
Urban afforestation is an important strategy for promoting sustainable urban development.In cities where large new green spaces are not available,the planting of curbside trees is deemed to be an important afforestati...Urban afforestation is an important strategy for promoting sustainable urban development.In cities where large new green spaces are not available,the planting of curbside trees is deemed to be an important afforestation strategy.However,variations in the ecosystem services provided by street tree assemblages across socioeconomic gradients have been unexplored.We examined such variations in ecosystem services provided by street tree assemblages along an urban–suburban continuum.Our findings were as follows.(i)Not all ecosystem services showed increasing trends along the urban–suburban continuum.Some ecosystem services at the street tree assemblage level,such as air purification and rainfall interception were prominent in areas of high urbanization intensity.(ii)Diverse ecosystem service trends were found in relation to differential characteristics of street trees assemblages.Structural properties of street tree assemblages,such as tree density and age structure,are likely key factors influencing variations.(iii)Although street tree density could partially compensate for the loss of large old trees,the protection of such trees is important because of their close associations with key ecosystem services,such as total carbon storage.To maximize the value of street trees in promoting urban sustainable development,trade-offs among multiple ecosystem services should be integrated within the overall planning process and adjustments of planting regimes.展开更多
Biodegradable polymeric nanoparticles are more and more frequently used in drug delivery systems, which represent one of the most rapidly developing areas. In our previous study, a novel natural hybrid polyester, poly...Biodegradable polymeric nanoparticles are more and more frequently used in drug delivery systems, which represent one of the most rapidly developing areas. In our previous study, a novel natural hybrid polyester, polyethylene glycol 200 （PEG200） end-capped poly （3-hydroxybutyrate-co-3-hydroxyhcxanoate） （PHBHHx-PEG） was directly produced by Aeromonas hydrophila fermentation. In this study, the performance of the novel biodegradable PHBHHx-PEG copolyester as a sustained release carrier for hydrophobic drugs with different molecular weights and the in vitro sustained release profile were investigated. 5-Fluorouracil （5-Fu, Mw=130.1）, TGX221 （Mw=364.4）, and Rapamycin （RAP, Mw=914.2） were used as the model drugs. PHBHHx-PEG nanoparticles entrapped with 5-Fu, TGX221 and RAP were fabricated by a modified emulsification/solvent evaporation method, respectively. The average diameter of 5-Fu, TGX221, and RAP loaded PHBHHx-PEG nanoparticles was between 198.2-217.4 nm, and the entrapment efficiency of the three drugs was 62.5%, 93.4% and 91.9%, respectively. The in vitro release profiles of 5-Fu, TGX221 and RAP from PHBHHx-PEG nanoparticles were different. 5-Fu showed faster release rate and an obvious initial burst release phase. TGX221 and RAP were demonstrated to be released more slowly and steadily. The release percentages of 5-Fu, TGX221 and RAP were 97.7%, 85.1% and 74.7% after releasing for 72 h. PHBHHx-PEG is a kind of promising material as a carrier for the entrapment and delivery of hydrophobic drugs especially for those drugs with high molecular weight.展开更多
基金Supported by"Twelfth Five-Year"National Scientific and Technological Support Project(2011BAD38B0602)~~
文摘[Objective] This study aimed to explore the relationship between different forest types and water conservation function. [Method] Based on field survey and experimental analysis, water conservation function of four typical forest stands in Jinyun Mountain of Chongqing was explored, including conifer-broadleaved mixed for- est, evergreen broad-leaved forest, bamboo forest and shrub forest. [Result] The re- sults showed that the order of saturated water storage capacity of soil in four forest stands was shrub forest （266.48 mm） 〉 conifer-broadleaved mixed forest （190.40 mm） 〉 evergreen broad-leaved forest （186.80 mm） 〉 bamboo forest （174.80 mm）; the order of maximum water-holding capacity of litter was shrub forest （8.06 mm） 〉 conifer-broadleaved mixed forest （4.71 mm） 〉 evergreen broad-leaved forest （4.32 mm） 〉 bamboo forest （3.34 mm）; the order of canopy interception in various forest stands was conifer-broadleaved mixed forest （16.15%） 〉 evergreen broad-leaved for- est （14.70%） 〉 bamboo forest （12.64%）. [Conclusion] The study had great signifi- cance to rational manage forest resources, improve water environment and realize scientific management and use of water resources.
基金supported by special funds of the National Natural Science Foundation of China (Grant No. 10274106)
文摘The three-dimensional structure of recombinant hepatitis B core antigen（HBcAg） particles truncated at residue 154（HBcAg-154） was determined to 7.8 A resolution by cryo-electron microscopy（cryoEM） and computer reconstruction.The capsid of HBcAg-154 is mainly constituted by α-helical folds,highly similar to that of HBcAg-149.The C-terminal region between residues 155 and 183 of the core protein is more crucial to the encapsidation of RNA,and the short C-terminal tail of HBcAg-154 results in a nearly empty capsid.
基金Funding for this study was provided by the National Natural Sciences Foundation of China(32130068,32171665).
文摘Urban afforestation is an important strategy for promoting sustainable urban development.In cities where large new green spaces are not available,the planting of curbside trees is deemed to be an important afforestation strategy.However,variations in the ecosystem services provided by street tree assemblages across socioeconomic gradients have been unexplored.We examined such variations in ecosystem services provided by street tree assemblages along an urban–suburban continuum.Our findings were as follows.(i)Not all ecosystem services showed increasing trends along the urban–suburban continuum.Some ecosystem services at the street tree assemblage level,such as air purification and rainfall interception were prominent in areas of high urbanization intensity.(ii)Diverse ecosystem service trends were found in relation to differential characteristics of street trees assemblages.Structural properties of street tree assemblages,such as tree density and age structure,are likely key factors influencing variations.(iii)Although street tree density could partially compensate for the loss of large old trees,the protection of such trees is important because of their close associations with key ecosystem services,such as total carbon storage.To maximize the value of street trees in promoting urban sustainable development,trade-offs among multiple ecosystem services should be integrated within the overall planning process and adjustments of planting regimes.
基金National Natural Science Foundation of Chinagrant number:81172170,81371288+1 种基金Science and Technology Research and Development Program of Shanxi Provincegrant number:2013KW32-04
文摘Biodegradable polymeric nanoparticles are more and more frequently used in drug delivery systems, which represent one of the most rapidly developing areas. In our previous study, a novel natural hybrid polyester, polyethylene glycol 200 （PEG200） end-capped poly （3-hydroxybutyrate-co-3-hydroxyhcxanoate） （PHBHHx-PEG） was directly produced by Aeromonas hydrophila fermentation. In this study, the performance of the novel biodegradable PHBHHx-PEG copolyester as a sustained release carrier for hydrophobic drugs with different molecular weights and the in vitro sustained release profile were investigated. 5-Fluorouracil （5-Fu, Mw=130.1）, TGX221 （Mw=364.4）, and Rapamycin （RAP, Mw=914.2） were used as the model drugs. PHBHHx-PEG nanoparticles entrapped with 5-Fu, TGX221 and RAP were fabricated by a modified emulsification/solvent evaporation method, respectively. The average diameter of 5-Fu, TGX221, and RAP loaded PHBHHx-PEG nanoparticles was between 198.2-217.4 nm, and the entrapment efficiency of the three drugs was 62.5%, 93.4% and 91.9%, respectively. The in vitro release profiles of 5-Fu, TGX221 and RAP from PHBHHx-PEG nanoparticles were different. 5-Fu showed faster release rate and an obvious initial burst release phase. TGX221 and RAP were demonstrated to be released more slowly and steadily. The release percentages of 5-Fu, TGX221 and RAP were 97.7%, 85.1% and 74.7% after releasing for 72 h. PHBHHx-PEG is a kind of promising material as a carrier for the entrapment and delivery of hydrophobic drugs especially for those drugs with high molecular weight.
