Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant co...Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant community structure,especially in forests,has not been fully elucidated.We investigated 68 plots in larch forests in northern China to explore how plant community structure and environmental factors affect the N-P stoichiometry of soil and leaves.The results showed significant differences in soil and leaf N-P stoichiometry among the three larch forests,P concentration and N:P ratio of leaves were significantly related to those of soil.Except for larch forest type,N-P stoichiometry was also regulated by elevation,climatic factors,and community structure.With increasing age(from 25 to 236 years),soil N and N:P ratio significantly increased,especially in the topsoil.With increasing mean DBH,leaf N concentration and N:P ratio also increased,indicating a shift in nutrient limitations with stand growth.These findings provide evidence that plant community structure and environmental factors regulate soil and leaf N-P stoichiometry,which is critically important for understanding biogeochemical cycles and forest management undergoing natural succession.展开更多
Low-concentration acetone detection is of great importance for acetone sensor in the fields of environmental protection and noninvasive diagnosis.In this work,mesoporous Fe_(2)O_(3)/Cr_(2)O_(3)n-p heterojunctions were...Low-concentration acetone detection is of great importance for acetone sensor in the fields of environmental protection and noninvasive diagnosis.In this work,mesoporous Fe_(2)O_(3)/Cr_(2)O_(3)n-p heterojunctions were constructed for efficient improvement of low-concentration acetone gas sensing.The gas-sensing results indicated that the mesoporous Fe_(2)O_(3)/Cr_(2)O_(3)composites with a significantly large specific surface area exhibited significantlyenhanced acetone gas-sensitive performance compared to pure Fe_(2)O_(3).The Fe_(2)O_(3)/Cr_(2)O_(3)composites demonstrated a high response,good selectivity and excellent stability over200 days to 10 ppm acetone at 220℃.And the theoretical detection limit was calculated to reach 0.285 ppm acetone.A feasible acetone sensing mechanism was proposed through electronic band structure and density functional theory.The improved low-concentration acetone sensing performance was due to the formed mesoporous Fe_(2)O_(3)/Cr_(2)O_(3)n-p heterojunctions with a large specific surface area.The Fe_(2)O_(3)/Cr_(2)O_(3)composites showed excellent acetone gas-sensitive performance,which could be a promising candidate for developing low-concentration acetone sensing devices at low working temperatures.展开更多
基金supported by the National Natural Science Foundation of China(No.32201426,No.31988102)the Major Program for Basic Research Project of Yunnan Province(No.202101BC070002)the Key Research and Development Program of Yunnan Provin ce(No.202303AC100009).
文摘Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant community structure,especially in forests,has not been fully elucidated.We investigated 68 plots in larch forests in northern China to explore how plant community structure and environmental factors affect the N-P stoichiometry of soil and leaves.The results showed significant differences in soil and leaf N-P stoichiometry among the three larch forests,P concentration and N:P ratio of leaves were significantly related to those of soil.Except for larch forest type,N-P stoichiometry was also regulated by elevation,climatic factors,and community structure.With increasing age(from 25 to 236 years),soil N and N:P ratio significantly increased,especially in the topsoil.With increasing mean DBH,leaf N concentration and N:P ratio also increased,indicating a shift in nutrient limitations with stand growth.These findings provide evidence that plant community structure and environmental factors regulate soil and leaf N-P stoichiometry,which is critically important for understanding biogeochemical cycles and forest management undergoing natural succession.
基金financially supported by the National Natural Science Foundation of China(Nos.62374154 and12374128)the National Key R&D Program of China(Nos.2022YFB3903200 and 2022YFB3903203)
文摘Low-concentration acetone detection is of great importance for acetone sensor in the fields of environmental protection and noninvasive diagnosis.In this work,mesoporous Fe_(2)O_(3)/Cr_(2)O_(3)n-p heterojunctions were constructed for efficient improvement of low-concentration acetone gas sensing.The gas-sensing results indicated that the mesoporous Fe_(2)O_(3)/Cr_(2)O_(3)composites with a significantly large specific surface area exhibited significantlyenhanced acetone gas-sensitive performance compared to pure Fe_(2)O_(3).The Fe_(2)O_(3)/Cr_(2)O_(3)composites demonstrated a high response,good selectivity and excellent stability over200 days to 10 ppm acetone at 220℃.And the theoretical detection limit was calculated to reach 0.285 ppm acetone.A feasible acetone sensing mechanism was proposed through electronic band structure and density functional theory.The improved low-concentration acetone sensing performance was due to the formed mesoporous Fe_(2)O_(3)/Cr_(2)O_(3)n-p heterojunctions with a large specific surface area.The Fe_(2)O_(3)/Cr_(2)O_(3)composites showed excellent acetone gas-sensitive performance,which could be a promising candidate for developing low-concentration acetone sensing devices at low working temperatures.
基金supported by the Natural Science Foundation of Heilongjiang Province (E201323)the Harbin Special Fund for Innovation Talents of Science and Technology (2013RFXXJ081)the Science and Technology Research Program of Education Bureau of Heilongjiang Province (12531213)~~
