In this paper, the methane adsorption behaviours in slit-like chlorite nanopores were investigated using the grand canonical Monte Carlo simulation method, and the influences of the pore sizes, temperatures, water, an...In this paper, the methane adsorption behaviours in slit-like chlorite nanopores were investigated using the grand canonical Monte Carlo simulation method, and the influences of the pore sizes, temperatures, water, and compositions on methane adsorption on chlorite were discussed. Our investigation revealed that the isosteric heat of adsorption of methane in slit-like chlorite nanopores decreased with an increase in pore size and was less than 42 kJ/mol, suggesting that methane adsorbed on chlorite through physical adsorption. The methane excess adsorp- tion capacity increased with the increase in the pore size in micropores and decreased with the increase in the pore size in mesopores. The methane excess adsorption capacity in chlorite pores increased with an increase in pressure or decrease in pore size. With an increase in temperature, the isosteric heats of adsorption of methane decreased and the methane adsorption sites on chlorite changed from lower- energy adsorption sites to higher-energy sites, leading to the reduction in the methane excess adsorption capacity. Water molecules in chlorite pores occupied the pore wall in a directional manner, which may be related to the van der Waals and Coulomb force interactions and the hydrogen bonding interaction. It was also found that water molecules existed as aggregates. With increasing water content, the water molecules occupied the adsorption sites and adsorption space of the methane, leading to a reduction in the methane excess adsorption capacity. The excess adsorption capacity of gas on chlorite decreased in the following order： carbon dioxide 〉 methane 〉 nitrogen. If the mole fraction of nitrogen or carbon dioxide in the binary gas mixture increased, the mole fraction of methane decreased, methane adsorption sites changed, and methane adsorption space was reduced, resulting in the decrease in the methane excess adsorption capacity.展开更多
Wellbore collapse frequently happens in the clay shale formation.To maintain wellbore stability,appropriate mud pressure is a vital factor.When clay formation is opened,drilling unloading occurs,modifying rock structu...Wellbore collapse frequently happens in the clay shale formation.To maintain wellbore stability,appropriate mud pressure is a vital factor.When clay formation is opened,drilling unloading occurs,modifying rock structure and strength at the wall of borehole,which affects the selection of mud pressure.Currently,mechanism of drilling unloading is still poorly understood which in return will bring a concern to wellbore stability.Therefore,in this study,a combination of triaxial compressive test and ultrasonic wave test has been used to simulate drilling unloading and analyze its mechanism.Results indicate that more void space is created inside the clay shale sample due to unloading.This structure change leads to a decline of strength and acoustic amplitude.Additionally,unloading influence is depended on varying drilling unloading parameters.Small unloading range and fast unloading rate are able to enhance stability.With various degrees of unloading impact,collapse pressure equivalent density has a clear modification,proving that unloading is a non-negligible influencing factor of wellbore stability.Besides,the unloading effect is much stronger in large confining pressure,implying that more attention should be given to unloading when drilling is in extreme deep or high geostress formation.Findings in this paper can offer theoretical guidance for drilling in the clay shale formation.展开更多
The Western Route of the South-to-North Water Transfer Project will divert water from the upper Yangtze River and its tributaries, the Dadu River and Yalong River, to the upper Yellow River. The project may ease the w...The Western Route of the South-to-North Water Transfer Project will divert water from the upper Yangtze River and its tributaries, the Dadu River and Yalong River, to the upper Yellow River. The project may ease the water shortage in the Yellow River Basin. However, it may also have some effects on the ecosystem in the upper Yangtze River Basin. Benthic invertebrates play an important role in the river ecosystem, particularly in the circulation of materials and nutrition. Benthic invertebrates are widely used to quickly assess river ecosystems because of their rapid response to changes in the water environment. The diversity of benthic invertebrates is closely associated with the aquatic habitat area. This study examined this interaction by sampling the benthic invertebrates in an expanding area. The conclusions are that the diversity of benthic invertebrates begins to decrease when the aquatic habitat area is reduced to 45% of the original area, and decreases dramatically when the aquatic habitat area is reduced to 10% of the original area. The aquatic habitat area should be kept at more than 45% of the original area in order to maintain the significant diversity of benthic invertebrates.展开更多
The influence of solute Ce,Mn,and Si on the mechanical properties of silicon steel was investigated by first-principles calculation.Ce,Mn,and Si can all be solubilized in Fe matrix.Ce significantly reduces the incompr...The influence of solute Ce,Mn,and Si on the mechanical properties of silicon steel was investigated by first-principles calculation.Ce,Mn,and Si can all be solubilized in Fe matrix.Ce significantly reduces the incompressibility and rigidity of the system but also significantly improves the toughness and machinability.The effect of Mn on mechanical properties of the system is not obvious.Si has a significant effect on the improvement in incompressibility and rigidity but a limited effect on the improvement in toughness and machinability.The metallic bond strength of Fe-Ce,Fe-Mn,and Fe-Si doped systems is weaker than that of the pure Fe system,which can be used to explain the reduction in the incompressibility and rigidity of these doped systems.The relatively high electron cloud density in the doped system may be responsible for the increase in toughness.展开更多
Automated test generation tools enable test automation and further alleviate the low efficiency caused by writing hand-crafted test cases.However,existing automated tools are not mature enough to be widely used by sof...Automated test generation tools enable test automation and further alleviate the low efficiency caused by writing hand-crafted test cases.However,existing automated tools are not mature enough to be widely used by software testing groups.This paper conducts an empirical study on the state-of-the-art automated tools for Java,i.e.,EvoSuite,Randoop,JDoop,JTeXpert,T3,and Tardis.We design a test workflow to facilitate the process,which can automatically run tools for test generation,collect data,and evaluate various metrics.Furthermore,we conduct empirical analysis on these six tools and their related techniques from different aspects,i.e.,code coverage,mutation score,test suite size,readability,and real fault detection ability.We discuss about the benefits and drawbacks of hybrid techniques based on experimental results.Besides,we introduce our experience in setting up and executing these tools,and summarize their usability and user-friendliness.Finally,we give some insights into automated tools in terms of test suite readability improvement,meaningful assertion generation,test suite reduction for random testing tools,and symbolic execution integration.展开更多
CO_(2)conversion is gradually seen as a better way for society to effectively use carbon sources and avoid climate crisis associated with fossil CO_(2)emissions.And the decision to deploy CO_(2)technology scale should...CO_(2)conversion is gradually seen as a better way for society to effectively use carbon sources and avoid climate crisis associated with fossil CO_(2)emissions.And the decision to deploy CO_(2)technology scale should be relied on its environmental impact.In this work,life cycle assessment model evaluates the environmental performance of CO_(2)conversion by photocatalytic reaction process with two different catalysts(NiAl-LDH and Co-ZIF-9).Six impact categories considered in this analysis,including climate change,acidification potential,depletion of abiotic resources,eutrophication potential,ozone layer depletion potential,and photochemical oxidation potential.Results indicated that CO_(2)conversion with Co-ZIF-9 photocatalyst has a better environmental impact than the NiAl-LDH photocatalyst route.Moreover,the Co-ZIF-9 catalyst scenario also has a lower total environmental burden than the conventional CO production route.Sensitivity analysis shows that recycle performance of the catalyst is highly sensitive to the production process in two scenarios.This study could provide a framework for robust decisions in CO_(2)conversion by photocatalytic reaction,which is useful for policymakers to decide the feasibility of industrialization.展开更多
Background：Antimicrobial resistance is a serious problem that compromises the empirical treatment of infections,resulting in a lack of effective antibiotics and high medical expenses.Here,we aimed to monitor the tren...Background：Antimicrobial resistance is a serious problem that compromises the empirical treatment of infections,resulting in a lack of effective antibiotics and high medical expenses.Here,we aimed to monitor the trends in antimicrobial resistance among Enterobacteriaceae isolated from blood samples in China's Mainland.Methods：A total of 2240 Enterobacteriaceae isolates from blood were collected from hospitalized patients at 19 tertiary hospitals between October 2004 and June 2014.The minimum inhibitory concentrations of all isolates were determined using the agar dilution method according to the Clinical and Laboratory Standards Institute 2016 guidelines.Results：The most commonly isolated bacteria were Escherichia coli,compromising 47.0% （1053/2240） of the total isolates,followed byKlebsiella spp.（26.3%）,Sahnonella spp.（10.4%）,and Enterobacter spp.（9.2%）.The detection rates of extended-spectrum β-lactamases （ESBLs） among E.coli were 68.9% （2004-2005）,73.2% （2007-2008）,67.9% （2009-2010）,72.6% （2011-2012）,and 58.4% （2013-2014）,whereas those in ESBL-producing Klebsiellapneumoniae were slightly decreased （75.9%,50.0%,41.4%,40.2%,and 43.0%,respectively）.Carbapenems were the most potent agents against the Enterobacteriaceae isolates,followed by moxalactam,tigecycline,and amikacin.However,there was a decrease in the susceptibility rates for carbapenems in all species,particularly K.pneumoniae （decreased by 10.6% for imipenem） and Enterobacter aerogenes （decreased by 2 l.1% for imipenem）.Reviving antibiotics （tigecycline and polymyxins） showed good in vitro activity against Enterobacteriaceae.Conclusions：The activity of antibiotics against Enterobacteriaceae isolated from blood was decreased overall.Large proportions of ESBL-producing isolates were identified among E.coli and Klebsiella spp.Carbapenem-resistant isolates have become a major challenge in the treatment of infections.展开更多
The binding energies,electronic structures and elastic properties of Ti,V,Cr,Mn,Co,Ni and Mg dopedα-Fe（N）systems have been investigated using a first-principles method.The calculated results show that the dopings o...The binding energies,electronic structures and elastic properties of Ti,V,Cr,Mn,Co,Ni and Mg dopedα-Fe（N）systems have been investigated using a first-principles method.The calculated results show that the dopings of Ti,V,Cr and Co improve the stability ofα-Fe（N）,and the stability ofα-Fe（N）is slightly weakened by Mn and Ni,and the doping of Mg is disadvantageous.For Ti,V,Cr and Mn dopedα-Fe（N）systems in which the doping metals are on the left side of Fe in the element periodic table andα-Fe（N）systems doped by Co and Ni on the right side of Fe,their corresponding cohesive forces decrease with decreasing atomic radius of the doping species.The obvious interaction exists among M3 d,Fe4s3p3d and N2 p.In these doping systems,metal atoms lose electrons,while N gains electrons.Dopings of Ti,V,Cr and Mn inα-Fe（N）strengthen the interaction between N and the surrounding metals,and it is not apparent for the dopings of Co,Ni and Mg.Elastic calculations of Fe15 MN systems show that,except for the Fe15 MgN system,shear modulus G and Young modulus E of Fe15 MN systems are improved,and the bulk modulus Bslightly decreases,namely,total elastic properties are enhanced.The magnitude change rule of E reflecting the cohesive force between atoms is consistent with that for the binding energies.展开更多
基金supported by the United Fund Project of National Natural Science Foundation of China (Grant No. U1262209)the National Natural Science Foundation of China (Grant No. 41602155)the Young Scholars Development Fund of SWPU (No. 201599010137)
文摘In this paper, the methane adsorption behaviours in slit-like chlorite nanopores were investigated using the grand canonical Monte Carlo simulation method, and the influences of the pore sizes, temperatures, water, and compositions on methane adsorption on chlorite were discussed. Our investigation revealed that the isosteric heat of adsorption of methane in slit-like chlorite nanopores decreased with an increase in pore size and was less than 42 kJ/mol, suggesting that methane adsorbed on chlorite through physical adsorption. The methane excess adsorp- tion capacity increased with the increase in the pore size in micropores and decreased with the increase in the pore size in mesopores. The methane excess adsorption capacity in chlorite pores increased with an increase in pressure or decrease in pore size. With an increase in temperature, the isosteric heats of adsorption of methane decreased and the methane adsorption sites on chlorite changed from lower- energy adsorption sites to higher-energy sites, leading to the reduction in the methane excess adsorption capacity. Water molecules in chlorite pores occupied the pore wall in a directional manner, which may be related to the van der Waals and Coulomb force interactions and the hydrogen bonding interaction. It was also found that water molecules existed as aggregates. With increasing water content, the water molecules occupied the adsorption sites and adsorption space of the methane, leading to a reduction in the methane excess adsorption capacity. The excess adsorption capacity of gas on chlorite decreased in the following order： carbon dioxide 〉 methane 〉 nitrogen. If the mole fraction of nitrogen or carbon dioxide in the binary gas mixture increased, the mole fraction of methane decreased, methane adsorption sites changed, and methane adsorption space was reduced, resulting in the decrease in the methane excess adsorption capacity.
基金This work was supported by the National Natural Science Foundation of China(No.41772151)the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2011ZX05020-007-06)the Application Basic Research Project of Sichuan Province(No.2014JY0092)。
文摘Wellbore collapse frequently happens in the clay shale formation.To maintain wellbore stability,appropriate mud pressure is a vital factor.When clay formation is opened,drilling unloading occurs,modifying rock structure and strength at the wall of borehole,which affects the selection of mud pressure.Currently,mechanism of drilling unloading is still poorly understood which in return will bring a concern to wellbore stability.Therefore,in this study,a combination of triaxial compressive test and ultrasonic wave test has been used to simulate drilling unloading and analyze its mechanism.Results indicate that more void space is created inside the clay shale sample due to unloading.This structure change leads to a decline of strength and acoustic amplitude.Additionally,unloading influence is depended on varying drilling unloading parameters.Small unloading range and fast unloading rate are able to enhance stability.With various degrees of unloading impact,collapse pressure equivalent density has a clear modification,proving that unloading is a non-negligible influencing factor of wellbore stability.Besides,the unloading effect is much stronger in large confining pressure,implying that more attention should be given to unloading when drilling is in extreme deep or high geostress formation.Findings in this paper can offer theoretical guidance for drilling in the clay shale formation.
基金supported by the National Hi-Tech Research and Development Program of China ("863" Project) (Grant No. 2006BAB04A08)the National Natural Science Foundation of China (Grant No. 50779027)
文摘The Western Route of the South-to-North Water Transfer Project will divert water from the upper Yangtze River and its tributaries, the Dadu River and Yalong River, to the upper Yellow River. The project may ease the water shortage in the Yellow River Basin. However, it may also have some effects on the ecosystem in the upper Yangtze River Basin. Benthic invertebrates play an important role in the river ecosystem, particularly in the circulation of materials and nutrition. Benthic invertebrates are widely used to quickly assess river ecosystems because of their rapid response to changes in the water environment. The diversity of benthic invertebrates is closely associated with the aquatic habitat area. This study examined this interaction by sampling the benthic invertebrates in an expanding area. The conclusions are that the diversity of benthic invertebrates begins to decrease when the aquatic habitat area is reduced to 45% of the original area, and decreases dramatically when the aquatic habitat area is reduced to 10% of the original area. The aquatic habitat area should be kept at more than 45% of the original area in order to maintain the significant diversity of benthic invertebrates.
基金supported by National Natural Science Foundation of China(No.52204364)China Postdoctoral Science Foundation(No.2021MD703850)+1 种基金Central Guidance on Local Science and Technology Development Fund Projects of Inner Mongolia Autonomous Region(No.2022ZY0090)Basic Scientific Research Business Expenses of Colleges and Universities in Inner Mongolia Autonomous Region(2023QNJS011).
文摘The influence of solute Ce,Mn,and Si on the mechanical properties of silicon steel was investigated by first-principles calculation.Ce,Mn,and Si can all be solubilized in Fe matrix.Ce significantly reduces the incompressibility and rigidity of the system but also significantly improves the toughness and machinability.The effect of Mn on mechanical properties of the system is not obvious.Si has a significant effect on the improvement in incompressibility and rigidity but a limited effect on the improvement in toughness and machinability.The metallic bond strength of Fe-Ce,Fe-Mn,and Fe-Si doped systems is weaker than that of the pure Fe system,which can be used to explain the reduction in the incompressibility and rigidity of these doped systems.The relatively high electron cloud density in the doped system may be responsible for the increase in toughness.
基金supported by the National Natural Science Foundation of China under Grant Nos.62072225 and 62025202.
文摘Automated test generation tools enable test automation and further alleviate the low efficiency caused by writing hand-crafted test cases.However,existing automated tools are not mature enough to be widely used by software testing groups.This paper conducts an empirical study on the state-of-the-art automated tools for Java,i.e.,EvoSuite,Randoop,JDoop,JTeXpert,T3,and Tardis.We design a test workflow to facilitate the process,which can automatically run tools for test generation,collect data,and evaluate various metrics.Furthermore,we conduct empirical analysis on these six tools and their related techniques from different aspects,i.e.,code coverage,mutation score,test suite size,readability,and real fault detection ability.We discuss about the benefits and drawbacks of hybrid techniques based on experimental results.Besides,we introduce our experience in setting up and executing these tools,and summarize their usability and user-friendliness.Finally,we give some insights into automated tools in terms of test suite readability improvement,meaningful assertion generation,test suite reduction for random testing tools,and symbolic execution integration.
基金funded by the National Natural Science Foundation of China(No.22108221)Qing-Yuan Yang acknowledges the ShccigQinling Program(SMYJY20220582)
文摘CO_(2)conversion is gradually seen as a better way for society to effectively use carbon sources and avoid climate crisis associated with fossil CO_(2)emissions.And the decision to deploy CO_(2)technology scale should be relied on its environmental impact.In this work,life cycle assessment model evaluates the environmental performance of CO_(2)conversion by photocatalytic reaction process with two different catalysts(NiAl-LDH and Co-ZIF-9).Six impact categories considered in this analysis,including climate change,acidification potential,depletion of abiotic resources,eutrophication potential,ozone layer depletion potential,and photochemical oxidation potential.Results indicated that CO_(2)conversion with Co-ZIF-9 photocatalyst has a better environmental impact than the NiAl-LDH photocatalyst route.Moreover,the Co-ZIF-9 catalyst scenario also has a lower total environmental burden than the conventional CO production route.Sensitivity analysis shows that recycle performance of the catalyst is highly sensitive to the production process in two scenarios.This study could provide a framework for robust decisions in CO_(2)conversion by photocatalytic reaction,which is useful for policymakers to decide the feasibility of industrialization.
文摘Background：Antimicrobial resistance is a serious problem that compromises the empirical treatment of infections,resulting in a lack of effective antibiotics and high medical expenses.Here,we aimed to monitor the trends in antimicrobial resistance among Enterobacteriaceae isolated from blood samples in China's Mainland.Methods：A total of 2240 Enterobacteriaceae isolates from blood were collected from hospitalized patients at 19 tertiary hospitals between October 2004 and June 2014.The minimum inhibitory concentrations of all isolates were determined using the agar dilution method according to the Clinical and Laboratory Standards Institute 2016 guidelines.Results：The most commonly isolated bacteria were Escherichia coli,compromising 47.0% （1053/2240） of the total isolates,followed byKlebsiella spp.（26.3%）,Sahnonella spp.（10.4%）,and Enterobacter spp.（9.2%）.The detection rates of extended-spectrum β-lactamases （ESBLs） among E.coli were 68.9% （2004-2005）,73.2% （2007-2008）,67.9% （2009-2010）,72.6% （2011-2012）,and 58.4% （2013-2014）,whereas those in ESBL-producing Klebsiellapneumoniae were slightly decreased （75.9%,50.0%,41.4%,40.2%,and 43.0%,respectively）.Carbapenems were the most potent agents against the Enterobacteriaceae isolates,followed by moxalactam,tigecycline,and amikacin.However,there was a decrease in the susceptibility rates for carbapenems in all species,particularly K.pneumoniae （decreased by 10.6% for imipenem） and Enterobacter aerogenes （decreased by 2 l.1% for imipenem）.Reviving antibiotics （tigecycline and polymyxins） showed good in vitro activity against Enterobacteriaceae.Conclusions：The activity of antibiotics against Enterobacteriaceae isolated from blood was decreased overall.Large proportions of ESBL-producing isolates were identified among E.coli and Klebsiella spp.Carbapenem-resistant isolates have become a major challenge in the treatment of infections.
基金the financial support from the National Natural Science Foundation of China(51364031)Produce-Learn-Research Project of Inner Mongolia University of Science&Technology(PY-201515)
文摘The binding energies,electronic structures and elastic properties of Ti,V,Cr,Mn,Co,Ni and Mg dopedα-Fe（N）systems have been investigated using a first-principles method.The calculated results show that the dopings of Ti,V,Cr and Co improve the stability ofα-Fe（N）,and the stability ofα-Fe（N）is slightly weakened by Mn and Ni,and the doping of Mg is disadvantageous.For Ti,V,Cr and Mn dopedα-Fe（N）systems in which the doping metals are on the left side of Fe in the element periodic table andα-Fe（N）systems doped by Co and Ni on the right side of Fe,their corresponding cohesive forces decrease with decreasing atomic radius of the doping species.The obvious interaction exists among M3 d,Fe4s3p3d and N2 p.In these doping systems,metal atoms lose electrons,while N gains electrons.Dopings of Ti,V,Cr and Mn inα-Fe（N）strengthen the interaction between N and the surrounding metals,and it is not apparent for the dopings of Co,Ni and Mg.Elastic calculations of Fe15 MN systems show that,except for the Fe15 MgN system,shear modulus G and Young modulus E of Fe15 MN systems are improved,and the bulk modulus Bslightly decreases,namely,total elastic properties are enhanced.The magnitude change rule of E reflecting the cohesive force between atoms is consistent with that for the binding energies.
