Aims Pulse effects of precipitation cause soil organic matter to rapidly decompose and release CO2 in a short period.The pulse effects of precipitation are important for ecosystem C cycling and soil C balance,although...Aims Pulse effects of precipitation cause soil organic matter to rapidly decompose and release CO2 in a short period.The pulse effects of precipitation are important for ecosystem C cycling and soil C balance,although their spatial variation in forest soils and the underlying mechanisms remain unclear.Methods Soil samples(0–10 cm)from 22 typical forest ecosystems in eastern China were used,to investigate the effects of simulated pulse precipitation on soil microbial respiration rates(Rs).We simulated pulsed precipitation to reach 65%water-holding capacity,the Rs was measured on a minute scale for 48 h.Important Findings Precipitation pulses can cause a rapid 1.70–38.12-fold increase in the rate of mineralized decomposing organic matter.Maximum Rs(_(Rs-soil-max)),cumulative Rs(A_(Rs-soil))and the time taken to arrive at the maximal Rs(T_(Rs-soil-max))were significant differences among different soil samples.Furthermore,the pulse effects in different climate zones were significantly different.R_(s-soil-max)(11.701μg C g^(-1)soil h^(-1))and A_(Rs-soil)(300.712μg C g^(-1) soil)were the highest in the mid-temperate zone.Soil chemical properties(total C and,N,pH and oxidation–reduction potential)and soil fractions were strongly correlated with the pulse effects in forest soils,but soil microbes contributed less.Our findings demonstrated that the pulse effects increase forest soil carbon emissions in the short term at a regional scale,and identified the factors with the greatest influence on this change.These findings help guide future studies on the C cycles of forest ecosystems and regulating ecosystem C cycles.展开更多
To shorten operation time and improve survival rate of rats with myocardial ischemia or myocardial infarction,we use a novel device comprised of a face mask and a head/neck retainer in this study.We report the basic d...To shorten operation time and improve survival rate of rats with myocardial ischemia or myocardial infarction,we use a novel device comprised of a face mask and a head/neck retainer in this study.We report the basic design of the novel respiratory face mask(RFM) and evaluate its performance in a rat model of myocardial ischemia.The device is cost-effective and easier to handle than other devices,such as tracheal intubation.Compared with conventional tracheal intubation,we found that RFM shortens operation time significantly while keeping blood indices normal;the mean operation time for rats in the mask group was(32±3) min,and that for the intubation group was(45±7) min(P<0.05).Moreover,the size and shape of the RFM can be changed according to the body weight of rats.In conclusion,RFM is an appropriate device for the establishment of myocardial infarction or ischemia-reperfusion in rats.展开更多
基金This study was financially supported by the NationalNatural Science Foundation of China(31988102,31770655,31800368).
文摘Aims Pulse effects of precipitation cause soil organic matter to rapidly decompose and release CO2 in a short period.The pulse effects of precipitation are important for ecosystem C cycling and soil C balance,although their spatial variation in forest soils and the underlying mechanisms remain unclear.Methods Soil samples(0–10 cm)from 22 typical forest ecosystems in eastern China were used,to investigate the effects of simulated pulse precipitation on soil microbial respiration rates(Rs).We simulated pulsed precipitation to reach 65%water-holding capacity,the Rs was measured on a minute scale for 48 h.Important Findings Precipitation pulses can cause a rapid 1.70–38.12-fold increase in the rate of mineralized decomposing organic matter.Maximum Rs(_(Rs-soil-max)),cumulative Rs(A_(Rs-soil))and the time taken to arrive at the maximal Rs(T_(Rs-soil-max))were significant differences among different soil samples.Furthermore,the pulse effects in different climate zones were significantly different.R_(s-soil-max)(11.701μg C g^(-1)soil h^(-1))and A_(Rs-soil)(300.712μg C g^(-1) soil)were the highest in the mid-temperate zone.Soil chemical properties(total C and,N,pH and oxidation–reduction potential)and soil fractions were strongly correlated with the pulse effects in forest soils,but soil microbes contributed less.Our findings demonstrated that the pulse effects increase forest soil carbon emissions in the short term at a regional scale,and identified the factors with the greatest influence on this change.These findings help guide future studies on the C cycles of forest ecosystems and regulating ecosystem C cycles.
基金(No.30600580) supported by the National Natural Science Foundation of China
文摘To shorten operation time and improve survival rate of rats with myocardial ischemia or myocardial infarction,we use a novel device comprised of a face mask and a head/neck retainer in this study.We report the basic design of the novel respiratory face mask(RFM) and evaluate its performance in a rat model of myocardial ischemia.The device is cost-effective and easier to handle than other devices,such as tracheal intubation.Compared with conventional tracheal intubation,we found that RFM shortens operation time significantly while keeping blood indices normal;the mean operation time for rats in the mask group was(32±3) min,and that for the intubation group was(45±7) min(P<0.05).Moreover,the size and shape of the RFM can be changed according to the body weight of rats.In conclusion,RFM is an appropriate device for the establishment of myocardial infarction or ischemia-reperfusion in rats.
