Here some steady-state experiments on oxidation of CO on Pd were performed on a molecular beam apparatus. It is found that the characteristics of the rate of CO_2 formation r versus substrate temperature T are depende...Here some steady-state experiments on oxidation of CO on Pd were performed on a molecular beam apparatus. It is found that the characteristics of the rate of CO_2 formation r versus substrate temperature T are dependent on the ratio P=P_(CO)/P_(O2) in the mixed beam. These characteristics are related to the complicated interactions of co-adsorbed CO and O particles on Pd surface.展开更多
A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity） 〈 90%. Four haze episodes, which accounted for ～ 60...A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity） 〈 90%. Four haze episodes, which accounted for ～ 60% of the time during the whole campaign, were characterized by increases of SNA（sulfate, nitrate, and ammonium） and SOA（secondary organic aerosol） concentrations. The average values with standard deviation of SO2-＋4, NO-3, NH4 and SOA were 49.8（± 31.6）, 31.4（±22.3）, 25.8（±16.6） and 8.9（±4.1） μg/m3, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO2-4,NO-3, NH＋4, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM10 during the non-haze days. The respective contributions of SNA species to PM10 rose to about27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM10 mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR（sulfur oxidation ratio） and NOR（nitrogen oxidation ratio） increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO2 to SO2-4and NO2 to NO-3, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing.展开更多
This work gives an introduction to the R package NORRRM whose main purpose is to calculate the CIPW Norm. Although there are many softwares and spreadsheets available to estimate the standard mineral assemblages in ig...This work gives an introduction to the R package NORRRM whose main purpose is to calculate the CIPW Norm. Although there are many softwares and spreadsheets available to estimate the standard mineral assemblages in igneous rocks, this package has the following advantages: a) it has the ability to be run on any operating computer systems (BSD, GNU/Linux, Mac OS X<sup>®</sup>, Windows<sup>®</sup>);b) an input argument allows choose different procedures to set the Fe-oxidation ratio;c) the options to use whole-rock major as well as minor oxides and trace elements in the computation;d) the output data yields highly consistent results achieving absolute match between the sum of the input weights of oxides recalculated on an anhydrous basis and the sum of the weights of estimated normative minerals and;e) the functions are written in R language and released under terms that guarantee users the freedom to study, adapt, modify, and distribute the software.展开更多
Anthropogenic environmental stressors（like atmospheric deposition,land use change,and climate warming） are predicted to increase inorganic nitrogen and organic carbon loading to northern boreal lakes,with potential ...Anthropogenic environmental stressors（like atmospheric deposition,land use change,and climate warming） are predicted to increase inorganic nitrogen and organic carbon loading to northern boreal lakes,with potential consequences for denitrification in lakes.However,our ability to predict effects of these changes is currently limited as northern boreal lakes have been largely neglected in denitrification studies.The aim of this study was therefore to assess how maximum potential denitrification and N_2O production rates,and the relationship between the two（relative N_2O production）,is controlled by availability of nitrate（NO_3^-）,carbon（C）,phosphorus（P）,and temperature.Experiments were performed using the acetylene inhibition technique on sediments from a small,nutrient poor boreal lake in northern Sweden in 2014.Maximum potential denitrification and N_2O production rates at 4°C were reached already at NO_3^-additions of 106–120 μg NO_3^-–N/L,and remained unchanged with higher NO_3 amendments.Higher incubation temperatures increased maximum potential denitrification and N_2O production rates,and Q10 was somewhat higher for N_2O production（1.77） than for denitrification（1.69）.The relative N_2O production ranged between 13% and 64%,and was not related to NO_3^-concentration,but the ratio increased when incubations were amended with C and P（from a median of 16% to 27%）.Combined,our results suggests that unproductive northern boreal lakes currently have low potential for denitrification but are susceptible to small changes in NO_3 loading especially if these are accompanied by enhanced C and P availability,likely promoting higher N_2O production relative to N_2.展开更多
The recovery of metal oxides from stainless steel dust using C（graphite）, SiFe, and Al as reductants was investigated under various conditions. The apparent distribution ratio of Cr（L Cr ′^m/s ） in the recovered ...The recovery of metal oxides from stainless steel dust using C（graphite）, SiFe, and Al as reductants was investigated under various conditions. The apparent distribution ratio of Cr（L Cr ′^m/s ） in the recovered metal and residual slag phases was defined as the major performance metric. The results show that the recovery ratio of metals increases as the ratio of CaO ：SiO2 by mass in the residual slag increases to 1.17. The residual content of metals in the slag decreases as the Al2O3 content of the slag is increased from approximately 8wt% to 10wt%. The recovery ratio of Cr increases with increasing L Cr ′^ m/s , and a linear relationship between L Cr ′^m/s and the activity coefficient ratio of CrO in the slag and the recovered metal phase is observed. The combination of C and SiFe or Al as the reducing agents reveals that Si is the more effective coreductant.展开更多
Hybrid rocket engines have gathered significant attention due to their ease of use,safety,and affordability associated with traditional chemical propulsion systems.They offer the advantage of on-demand throttle and th...Hybrid rocket engines have gathered significant attention due to their ease of use,safety,and affordability associated with traditional chemical propulsion systems.They offer the advantage of on-demand throttle and thrust adjustments.The performance of hybrid rocket engines depends on the regression rate,which is the transition of the solid fuel grain to flammable gas.Unlike solid and liquid engines,hybrids experience varying oxidizer-to-fuel(O/F)ratios over time.Factors such as changes in oxidizer flow and fuel port diameter contribute to this fluctuation,leading to incomplete combustion and reduced efficiency.To enhance hybrid rocket engine performance,ongoing research explores various methods.One approach is increasing the oxidizer flow velocity over the burning fuel surface.This paper employs analytical and numerical techniques to determine the effective oxidizer/fuel ratio for a single-port fuel grain in a hybrid rocket engine.Ultimately,the research aims to optimize performance,allowing this secure and efficient propulsion technology to mature.展开更多
基金Project supported by National Natural Science Foundation of China
文摘Here some steady-state experiments on oxidation of CO on Pd were performed on a molecular beam apparatus. It is found that the characteristics of the rate of CO_2 formation r versus substrate temperature T are dependent on the ratio P=P_(CO)/P_(O2) in the mixed beam. These characteristics are related to the complicated interactions of co-adsorbed CO and O particles on Pd surface.
基金supported by the National Natural Science Foundation of China (Nos. 41475113, 41175018)the CAS Strategic Priority Research Program (No. XDB05010500)
文摘A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity） 〈 90%. Four haze episodes, which accounted for ～ 60% of the time during the whole campaign, were characterized by increases of SNA（sulfate, nitrate, and ammonium） and SOA（secondary organic aerosol） concentrations. The average values with standard deviation of SO2-＋4, NO-3, NH4 and SOA were 49.8（± 31.6）, 31.4（±22.3）, 25.8（±16.6） and 8.9（±4.1） μg/m3, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO2-4,NO-3, NH＋4, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM10 during the non-haze days. The respective contributions of SNA species to PM10 rose to about27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM10 mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR（sulfur oxidation ratio） and NOR（nitrogen oxidation ratio） increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO2 to SO2-4and NO2 to NO-3, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing.
文摘This work gives an introduction to the R package NORRRM whose main purpose is to calculate the CIPW Norm. Although there are many softwares and spreadsheets available to estimate the standard mineral assemblages in igneous rocks, this package has the following advantages: a) it has the ability to be run on any operating computer systems (BSD, GNU/Linux, Mac OS X<sup>®</sup>, Windows<sup>®</sup>);b) an input argument allows choose different procedures to set the Fe-oxidation ratio;c) the options to use whole-rock major as well as minor oxides and trace elements in the computation;d) the output data yields highly consistent results achieving absolute match between the sum of the input weights of oxides recalculated on an anhydrous basis and the sum of the weights of estimated normative minerals and;e) the functions are written in R language and released under terms that guarantee users the freedom to study, adapt, modify, and distribute the software.
基金The Swedish Research Council for Environment,Agricultural Sciences and Spatial Planning (Formas).(No.215-2010-992)
文摘Anthropogenic environmental stressors（like atmospheric deposition,land use change,and climate warming） are predicted to increase inorganic nitrogen and organic carbon loading to northern boreal lakes,with potential consequences for denitrification in lakes.However,our ability to predict effects of these changes is currently limited as northern boreal lakes have been largely neglected in denitrification studies.The aim of this study was therefore to assess how maximum potential denitrification and N_2O production rates,and the relationship between the two（relative N_2O production）,is controlled by availability of nitrate（NO_3^-）,carbon（C）,phosphorus（P）,and temperature.Experiments were performed using the acetylene inhibition technique on sediments from a small,nutrient poor boreal lake in northern Sweden in 2014.Maximum potential denitrification and N_2O production rates at 4°C were reached already at NO_3^-additions of 106–120 μg NO_3^-–N/L,and remained unchanged with higher NO_3 amendments.Higher incubation temperatures increased maximum potential denitrification and N_2O production rates,and Q10 was somewhat higher for N_2O production（1.77） than for denitrification（1.69）.The relative N_2O production ranged between 13% and 64%,and was not related to NO_3^-concentration,but the ratio increased when incubations were amended with C and P（from a median of 16% to 27%）.Combined,our results suggests that unproductive northern boreal lakes currently have low potential for denitrification but are susceptible to small changes in NO_3 loading especially if these are accompanied by enhanced C and P availability,likely promoting higher N_2O production relative to N_2.
基金financially supported by the National Natural Science Foundation of China (No. 51474021)the Fundamental Research Funds for the Central Universities of China (No. FRF-SD-12-009A)
文摘The recovery of metal oxides from stainless steel dust using C（graphite）, SiFe, and Al as reductants was investigated under various conditions. The apparent distribution ratio of Cr（L Cr ′^m/s ） in the recovered metal and residual slag phases was defined as the major performance metric. The results show that the recovery ratio of metals increases as the ratio of CaO ：SiO2 by mass in the residual slag increases to 1.17. The residual content of metals in the slag decreases as the Al2O3 content of the slag is increased from approximately 8wt% to 10wt%. The recovery ratio of Cr increases with increasing L Cr ′^ m/s , and a linear relationship between L Cr ′^m/s and the activity coefficient ratio of CrO in the slag and the recovered metal phase is observed. The combination of C and SiFe or Al as the reducing agents reveals that Si is the more effective coreductant.
文摘Hybrid rocket engines have gathered significant attention due to their ease of use,safety,and affordability associated with traditional chemical propulsion systems.They offer the advantage of on-demand throttle and thrust adjustments.The performance of hybrid rocket engines depends on the regression rate,which is the transition of the solid fuel grain to flammable gas.Unlike solid and liquid engines,hybrids experience varying oxidizer-to-fuel(O/F)ratios over time.Factors such as changes in oxidizer flow and fuel port diameter contribute to this fluctuation,leading to incomplete combustion and reduced efficiency.To enhance hybrid rocket engine performance,ongoing research explores various methods.One approach is increasing the oxidizer flow velocity over the burning fuel surface.This paper employs analytical and numerical techniques to determine the effective oxidizer/fuel ratio for a single-port fuel grain in a hybrid rocket engine.Ultimately,the research aims to optimize performance,allowing this secure and efficient propulsion technology to mature.
