The lower Cambrian Qiongzhusi(Є1 q)shale in the Sichuan Basin,formerly considered a source rock,recently achieved high gas production(7.388×105 m^(3)·d^(-1))from well Z201 in the Deyang-Anyue rift trough(DAR...The lower Cambrian Qiongzhusi(Є1 q)shale in the Sichuan Basin,formerly considered a source rock,recently achieved high gas production(7.388×105 m^(3)·d^(-1))from well Z201 in the Deyang-Anyue rift trough(DART),marking an exploration breakthrough of the world’s oldest industrial shale gas reser-voir.However,the shale gas enrichment mechanism within the DART is not fully understood.This study reviews the formation of the Qiongzhusi shale gas reservoirs within the DART by comparing them with cotemporaneous deposits outside the DART,and several findings are presented.The gas production interval was correlated with the main phase of the Cambrian explosion(lower Cambrian stage 3).In the early Cambrian ecosystem,dominant animals likely accelerated the settling rates of organic matter(OM)in the upper 1st member ofЄ_(1) q(Є_(1) q_(12))by feeding on small planktonic organisms and producing larger organic fragments and fecal pellets.High primary productivity and euxinic con-ditions contributed to OM enrichment in the lower 1st member ofЄ1 q(Є_(1) q_(11)).Additionally,shale reservoirs inside the DART demonstrated better properties than those outside in terms of thickness,brittle minerals,gas content,and porosity.In particular,the abundant OM pores inside the DART facil-itated shale gas enrichment,whereas the higher thermal maturity of the shales outside the DART pos-sibly led to the graphitization and collapse of some OM pores.Meanwhile,the overpressure of high-production wells inside the DART generally reflects better shale gas preservation,benefiting from the shale’s self-sealing nature,"upper capping and lower plugging"configuration,and limited faults and microfractures.Considering these insights,we introduced a"ternary enrichment"model for the Qiongzhusi shale gas.Although the current high gas production of Z201 was found at the reservoir 3,two additional reservoirs were identified with significant potential,thus suggesting a"multilayer stereoscopic development"strategy in future shale gas exploration within the DART.展开更多
The commercial exploitation of unconventional petroleum resources(e.g.,shale oil/gas and tight oil/gas)has drastically changed the global energy structure within the past two decades.Sweet-spot intervals(areas),the mo...The commercial exploitation of unconventional petroleum resources(e.g.,shale oil/gas and tight oil/gas)has drastically changed the global energy structure within the past two decades.Sweet-spot intervals(areas),the most prolific unconventional hydrocarbon resources,generally consist of extraordinarily high organic matter(EHOM)deposits or closely associated sandstones/carbonate rocks.The formation of sweet-spot intervals(areas)is fundamentally controlled by their depositional and subsequent diagenetic settings,which result from the coupled sedimentation of global or regional geological events,such as tectonic activity,sea level(lake level)fluctuations,climate change,bottom water anoxia,volcanic activity,biotic mass extinction or radiation,and gravity flows during a certain geological period.Black shales with EHOM content and their associated high-quality reservoir rocks deposited by the coupling of major geological events provide not only a prerequisite for massive hydrocarbon generation but also abundant hydrocarbon storage space.The Ordovician-Silurian Wufeng-Longmaxi shale of the Sichuan Basin,Devonian Marcellus shale of the Appalachian Basin,Devonian-Carboniferous Bakken Formation of the Williston Basin,and Triassic Yanchang Formation of the Ordos Basin are four typical unconventional hydrocarbon systems selected as case studies herein.In each case,the formation of sweet-spot intervals for unconventional hydrocarbon resources was controlled by the coupled sedimentation of different global or regional geological events,collectively resulting in a favorable environment for the production,preservation,and accumulation of organic matter,as well as for the generation,migration,accumulation,and exploitation of hydrocarbons.Unconventional petroleum sedimentology,which focuses on coupled sedimentation during dramatic environmental changes driven by major geological events,is key to improve the understanding of the formation and distribution of sweet-spot intervals(areas)in unconventional petroleum systems.展开更多
DNA-based biosensors have played a huge role in many areas,especially in current global coronavirus outbreak.However,there is a great difficulty in the characterization of piezoelectric and flexoelectric coefficients ...DNA-based biosensors have played a huge role in many areas,especially in current global coronavirus outbreak.However,there is a great difficulty in the characterization of piezoelectric and flexoelectric coefficients of the nanoscale DNA film,because the existing experimental methods for hard materials are almost invalid.In addition,the relevant theoretical models for DNA films only consider a single effect without clarifying the difference between the two electromechanical effects on device detection signals.This work aims to present multiscale models for DNA-microcantilever experiments to clarify the competitive mechanism in piezoelectric and flexoelectric effects of DNA films on detection signals.First,a Poisson-Boltzmann(PB)equation is used to predict the potential distribution due to the competition between fixed phosphate groups and mobile salt ions in DNA films.Second,a macroscopic piezoelectric/flexoelectric constitutive equation of the DNA film and a mesoscopic free energy model of the DNA solution are combined to analytically predict the electromechanical coefficients of the DNA film and the relevant microcantilever signals by the deformation equivalent method and Zhang’s two-variable method.Finally,the effects of detection conditions on microscopic interactions,electromechanical coupling coefficients,and deflection signals are studied.Numerical results not only agree well with the experimental observations,but also reveal that the piezoelectric and flexoelectric effects of the DNA film should be equivalently modeled when interpreting microcantilever detection signals.These insights might provide opportunities for the microcantilever biosensor with high sensitivity.展开更多
DNA nanotubes(DNTs)with user-defined shapes and functionalities have potential applications in many fields.So far,compared with numerous experimental studies,there have been only a handful of models on the mechanical ...DNA nanotubes(DNTs)with user-defined shapes and functionalities have potential applications in many fields.So far,compared with numerous experimental studies,there have been only a handful of models on the mechanical properties of such DNTs.This paper aims at presenting a multiscale model to quantify the correlations among the pre-tension states,tensile properties,encapsulation structures of DNTs,and the surrounding factors.First,by combining a statistical worm-like-chain(WLC)model of single DNA deformation and Parsegian's mesoscopic model of DNA liquid crystal free energy,a multiscale tensegrity model is established,and the pre-tension state of DNTs is characterized theoretically for the first time.Then,by using the minimum potential energy principle,the force-extension curve and tensile rigidity of pre-tension DNTs are predicted.Finally,the effects of the encapsulation structure and surrounding factors on the tensile properties of DNTs are studied.The predictions for the tensile behaviors of DNTs can not only reproduce the existing experimental results,but also reveal that the competition of DNA intrachain and interchain interactions in the encapsulation structures determines the pre-tension states of DNTs and their tensile properties.The changes in the pre-tension states and environmental factors make the monotonic or non-monotonic changes in the tensile properties of DNTs under longitudinal loads.展开更多
Time-dependent behaviors due to various mismatch strains are very important to the reliability of micro-/nano-devices.This paper aims at presenting an analytical model to study the viscoelastic stress relaxation of th...Time-dependent behaviors due to various mismatch strains are very important to the reliability of micro-/nano-devices.This paper aims at presenting an analytical model to study the viscoelastic stress relaxation of the laminated microbeam caused by mismatch strain.Firstly,Zhang’s two-variable method is used to establish a mechanical model for predicting the quasi-static stress relaxation of the laminated microbeam.Secondly,the related analytical solutions are obtained by combining the differential method and the eigenvalue method in the temporal domain.Finally,the influence of the substrateto-film thickness/modulus ratio on the relaxation responses of the laminated microbeam subject to a step load of the mismatch strain is studied.The results show that the present predictions are consistent with the previous theoretical studies.Furthermore,the thickness dependence of stress relaxation time of the laminated microbeam is jointly determined by the intrinsic structural evolution factors and tension-bending coupling state;the stress relaxation time can be controlled by adjusting the substrate-to-film thickness/modulus ratio.展开更多
Houston,Texas,is one of the earliest regions to employ continuous GPS technology for land subsidence monitoring.Currently,there are over 200 permanent GPS stations located in the greater Houston area.The need for a co...Houston,Texas,is one of the earliest regions to employ continuous GPS technology for land subsidence monitoring.Currently,there are over 200 permanent GPS stations located in the greater Houston area.The need for a consistent and stable reference frame to precisely interpret local ground deformation has become critically important since the 1990s,because of the significant spreading of subsidence.We have established a stable Houston reference frame,designated Houston16,using publicly available GPS observations(>5 years)from 15 Continuously Operating Reference Stations(CORS)located outside of the greater Houston area.Applications of the reference frame in subsidence and faulting studies are demonstrated in this article.Houston16 is aligned in origin and scale with the International GNSS Reference Frame of 2008(IGS08).A 7-parameter method was employed to transform the GPS-derived positional time series from IGS08 to Houston16.The primary product of this study is the seven parameters for transforming Earth-Centered-Earth-Fixed XYZ coordinates from IGS08 to Houston16.The frame stability of Houston16 is approximately 1 mm/year.Houston16 will be updated every few years to mitigate degradation of the frame’s stability with time and to synchronize with future updates of the IGS reference frame.展开更多
In the process of my country’s energy transition,the clean energy of hydropower,wind power and photovoltaic power generation has ushered in great development,but due to the randomness and volatility of its output,it ...In the process of my country’s energy transition,the clean energy of hydropower,wind power and photovoltaic power generation has ushered in great development,but due to the randomness and volatility of its output,it has caused a certain waste of clean energy power generation resources.Regarding the purchase and sale of electricity by electricity retailers under the condition of limited clean energy consumption,this paper establishes a quantitative model of clean energy restricted electricity fromthe perspective of power system supply and demand balance.Then it analyzes the source-charge dual uncertain factors in the electricity retailer purchasing and selling scenarios in the mid-to long-term electricity market and the day-ahead market.Through the multi-scenario analysis method,the uncertain clean energy consumption and the user’s power demand are combined to form the electricity retailer’s electricity purchase and sales scene,and the typical scene is obtained by using the hierarchical clustering algorithm.This paper establishes a electricity retailer’s risk decisionmodel for purchasing and selling electricity in themid-and long-term market and reduce-abandonment market,and takes the maximum profit expectation of the electricity retailer frompurchasing and selling electricity as the objective function.At the same time,in themediumand longterm electricity market and the day-ahead market,the electricity retailer’s purchase cost,electricity sales income,deviation assessment cost and electricity purchase and sale risk are considered.The molecular results show that electricity retailers can obtain considerable profits in the reduce-abandonment market by optimizing their own electricity purchase and sales strategies,on the premise of balancing profits and risks.展开更多
Swine are regarded as“intermediate hosts”or“mixing vessels”of influenza viruses,capable of generating strains with pandemic potential.From 2020 to 2021,we conducted surveillance on swine H1N2 influenza(swH1N2)viru...Swine are regarded as“intermediate hosts”or“mixing vessels”of influenza viruses,capable of generating strains with pandemic potential.From 2020 to 2021,we conducted surveillance on swine H1N2 influenza(swH1N2)viruses in swine farms located in Guangdong,Yunnan,and Guizhou provinces in southern China,as well as Henan and Shandong provinces in northern China.We systematically analyzed the evolution and pathogenicity of swH1N2 isolates,and characterized their replication and transmission abilities.The isolated viruses are quadruple reassortant H1N2 viruses containing genes from pdm/09 H1N1(PB2,PB1,PA and NP genes),triple-reassortant swine(NS gene),Eurasian Avian-like(HA and M genes),and recent human H3N2(NA gene)lineages.The NA,PB2,and NP of SW/188/20 and SW/198/20 show high gene similarities to A/Guangdong/Yue Fang277/2017(H3N2).The HA gene of swH1N2 exhibits a high evolutionary rate.The five swH1N2 isolates replicate efficiently in human,canine,and swine cells,as well as in the turbinate,trachea,and lungs of mice.A/swine/Shandong/198/2020 strain efficiently replicates in the respiratory tract of pigs and effectively transmitted among them.Collectively,these current swH1N2 viruses possess zoonotic potential,highlighting the need for strengthened surveillance of swH1N2 viruses.展开更多
In recent years,significant progress in shale gas exploration has been achieved in the Upper Ordovician(Wufeng Formation)–Lower Silurian(Longmaxi Formation)shales in the Upper Yangtze area,South China.Although many s...In recent years,significant progress in shale gas exploration has been achieved in the Upper Ordovician(Wufeng Formation)–Lower Silurian(Longmaxi Formation)shales in the Upper Yangtze area,South China.Although many studies have been carried out on the Upper Ordovician–Lower Silurian shales,the controlling factors causing organic matter accumulation of these shales remain controversial.This study uses trace-element geochemistry and sedimentological methods to evaluate terrigenous input,redox conditions and primary productivity to explore the mechanisms of organic matter accumulation.The variation of terrigenous fraction elements(Al,Th and Sc)concentrations reflect a mixed influence of sea-level change and weathering.The sea-level of the Upper Yangtze Sea went through two cycles of transgression to regression during the Ordovician–Silurian transition.The Linxiang Formation,Kuanyinchiao Bed and the upper part of Longmaxi Formation developed during the periods of regression,whereas the Wufeng Formation and the lower part of the Longmaxi Formation developed during the periods of transgression.The paleo-productivity indexes of TOC content,ratios of Ba/Al and P/Al,and redox conditions proxies of Mo concentration,ratios of U/Th and V/Cr generally display similar variation patterns with respect to the sea-level changes.High TOC contents and Ba/Al and P/Al ratios indicate the paleo-productivity was high on the sea surface,as shown by relatively good positive correlations between Th vs.TOC,and Sc vs.TOC.This indicates that the paleo-productivity was controlled by the nutrients input through weathering.The good positive correlations between redox conditions indexes(U/Th and V/Cr ratios)with TOC content reflects reductive preservation conditions(anoxic to euxinic),thus implying they were an important controlling factor for organic matter accumulation.Nevertheless,redox conditions were closely associated with sea level change and organic matter decomposition.Therefore,the sea-level change and weathering were the primary controlling factors for organic matter enrichment across the Ordovician to Silurian transition.展开更多
0 INTRODUCTION The breakthroughs in unconventional petroleum have a great impact on world petroleum industry and innovation in petroleum geology(Dou et al,2022;Jia,2017;Zou et al.,2015b,2014a;Yerkin,2012;Pollastro,200...0 INTRODUCTION The breakthroughs in unconventional petroleum have a great impact on world petroleum industry and innovation in petroleum geology(Dou et al,2022;Jia,2017;Zou et al.,2015b,2014a;Yerkin,2012;Pollastro,2007;Schmoker,1995).The exploration and development evolution from conventional petroleum to unconventional petroleum and more and more frequent industrial activities of exploring petroleum inside sources kitchen have deepened theoretical understanding of unconventional petroleum geology and promoted technical research and development(Jia et al.,2021,2017;Jin et al.,2021;Zhao W Z et al.,2020;Ma Y S et al.,2018,2012;Zou et al.,2018b,2016,2009;Dai et al.,2012).We have introduced and extended the theory of continuous hydrocarbon accumulation since 2008 and published several papers/books(in Chinese and English)with respect to unconventional petroleum geology since 2009,basically forming the theoretical framework for this discipline(Yang et al.,2022a,2021a,2019a,,2015a;Zou et al.,2019c,2017b,2014a,,2013a).In this paper,we present the background of unconventional petroleum geology,review the latest theoretical and technological progress in unconventional petroleum geology,introduce relevant thinking and practices in China,and explore the pathway of unconventional petroleum revolution and multi-energy coordinated development in super energy basins,hopefully to promote the unconventional petroleum geology and industry development.展开更多
Mid-high maturity shale oil is the most realistic field for the scale breakthrough of terrestrial shale oil production in China.Generally,three deficiencies hinder shale oil development in China:heavy oil density,smal...Mid-high maturity shale oil is the most realistic field for the scale breakthrough of terrestrial shale oil production in China.Generally,three deficiencies hinder shale oil development in China:heavy oil density,small sweet spot areas,and poor distribution continuity.Thus,identifying the“sweet spots”in shale oil reservoirs is critical for the efficient exploration and development of terrestrial shale oil.This study targets the siltstone type(Class-Ⅱshale oil)and pure shale type(Class-Ⅲshale oil)of the Chang 7 Member in the Ordos Basin,and identifies three stratigraphic units,namely the hydrocarbon accumulation unit,hydrocarbon generation unit,and hydrocarbon retention unit,which together constitute the in-source“shale oil system”.The hydrocarbon accumulation unit is mainly siltstone,where the hydrocarbons are migrated from shales.It has favorable porethroat network connectivity with a pore connectivity ratio of 32–57%,being the siltstone-type sweet spots.The hydrocarbon generation unit is mainly composed of high-TOC mudstone/shale and is the main contributor to in-source hydrocarbon generation and expulsion.This unit has high three-dimensional connectivity(28–30%),as shown by the pore-throat network model,associated with vertical paths for hydrocarbon expulsion.The hydrocarbon retention unit is mainly composed of low-TOC mudstone/shale retaining self-generated and migrated hydrocarbons.The pore connectivity rate is 17–42%,and the pore-throat network connectivity direction is uneven.Light and low-carbon-number hydrocarbons are preferentially trapped or even sealed in small pores of the retention unit,forming the typical mudstone/shale-type sweet spots.In the process called shale oil intrasource migration,the oil migrates in source rocks causing component fractionation,which allows more shale oil to enrich in the hydrocarbon accumulation and retention units to form sweet spots,compared with the hydrocarbon generation unit.The migration paths include the one from mudstone/shale to siltstone interlayers and that from the high-TOC mudstone/shale intervals to the low-TOC intervals.The in-source accumulation of shale oil shows the differentiated enrichment model featuring“high-TOC mudstone/shale generating hydrocarbons,low-TOC mudstone/shale retaining hydrocarbons,siltstone accumulating hydrocarbons and multiple intra-source migration paths”.In the Ordos Basin,the organic-lean(TOC 1–3%)mudstone/shale intervals appear to be the sweet spots of shale oil,where there are abundant medium-short-chain hydrocarbons retained with high flowability.After fracturing stimulation,their production conditions may be even superior to those of siltstones.This proposed idea changes the previous strategy to look for sweet spots in high-TOC intervals derived from the shale gas industry.展开更多
Considering its rapid lithiation/delithiation process and robust capacitive energy storage,hierarchical porous carbon is regarded as a promising candidate for lithium-ion batteries(LIBs).However,it remains a great cha...Considering its rapid lithiation/delithiation process and robust capacitive energy storage,hierarchical porous carbon is regarded as a promising candidate for lithium-ion batteries(LIBs).However,it remains a great challenge to construct a porous structure and prevent structure stacking for carbon-based materials.Herein,a templatemediated approach is developed to synthesize hierarchical nitrogen-sulfur co-doped porous carbon(NSPC)using low-cost asphalt precursors.The strategy for synthesis uses g-C_(3)N_(4) and NaHCO_(3) as gaseous templates and NaCl as a solid template,which causes the formation of hierarchical porous carbon with a high specific surface area.The resultant porous structure and nitrogen-doping process can prevent the aggregation of nanosheets,maintain the structural stability upon cycling,and achieve rate-capable lithium storage.Serving as a LIBs anode,reversible specific capacities of the NSPC24 electrode reach 788 and 280 mAh·g^(-1) at 0.1 and 1 A·g^(-1),respectively.Furthermore,its specific capacity remains at 830 mAh·g^(-1) after 115 cycles at 0.1 A·g^(-1).Even after 500 cycles,high specific capacities of 727 mAh·g^(-1) at 0.5 A·g^(-1) and 624 mAh·g^(-1) at 1 A·g^(-1) are achieved,demonstrating excellent cycling performance.The gas-solid bifunctional template-mediated approach can guide the design of porous materials very well,meanwhile realizing the high value-added utilization of asphalt.展开更多
基金supported by the National Natural Science Foundation of China(U23B20155 and 42303004)China Postdoctoral Science Foundation(2023M730038)+1 种基金the Science and Technology Research Project for the China National Petroleum Corporation(2021DJ1802 and 2021YJCQ03)the National Postdoctoral Researcher Program of China(GZC20233111).
文摘The lower Cambrian Qiongzhusi(Є1 q)shale in the Sichuan Basin,formerly considered a source rock,recently achieved high gas production(7.388×105 m^(3)·d^(-1))from well Z201 in the Deyang-Anyue rift trough(DART),marking an exploration breakthrough of the world’s oldest industrial shale gas reser-voir.However,the shale gas enrichment mechanism within the DART is not fully understood.This study reviews the formation of the Qiongzhusi shale gas reservoirs within the DART by comparing them with cotemporaneous deposits outside the DART,and several findings are presented.The gas production interval was correlated with the main phase of the Cambrian explosion(lower Cambrian stage 3).In the early Cambrian ecosystem,dominant animals likely accelerated the settling rates of organic matter(OM)in the upper 1st member ofЄ_(1) q(Є_(1) q_(12))by feeding on small planktonic organisms and producing larger organic fragments and fecal pellets.High primary productivity and euxinic con-ditions contributed to OM enrichment in the lower 1st member ofЄ1 q(Є_(1) q_(11)).Additionally,shale reservoirs inside the DART demonstrated better properties than those outside in terms of thickness,brittle minerals,gas content,and porosity.In particular,the abundant OM pores inside the DART facil-itated shale gas enrichment,whereas the higher thermal maturity of the shales outside the DART pos-sibly led to the graphitization and collapse of some OM pores.Meanwhile,the overpressure of high-production wells inside the DART generally reflects better shale gas preservation,benefiting from the shale’s self-sealing nature,"upper capping and lower plugging"configuration,and limited faults and microfractures.Considering these insights,we introduced a"ternary enrichment"model for the Qiongzhusi shale gas.Although the current high gas production of Z201 was found at the reservoir 3,two additional reservoirs were identified with significant potential,thus suggesting a"multilayer stereoscopic development"strategy in future shale gas exploration within the DART.
基金jointly supported by the Scientific Research and Technological Development Programs of CNPC(2021yjcq02 and 2021DJ2001)。
文摘The commercial exploitation of unconventional petroleum resources(e.g.,shale oil/gas and tight oil/gas)has drastically changed the global energy structure within the past two decades.Sweet-spot intervals(areas),the most prolific unconventional hydrocarbon resources,generally consist of extraordinarily high organic matter(EHOM)deposits or closely associated sandstones/carbonate rocks.The formation of sweet-spot intervals(areas)is fundamentally controlled by their depositional and subsequent diagenetic settings,which result from the coupled sedimentation of global or regional geological events,such as tectonic activity,sea level(lake level)fluctuations,climate change,bottom water anoxia,volcanic activity,biotic mass extinction or radiation,and gravity flows during a certain geological period.Black shales with EHOM content and their associated high-quality reservoir rocks deposited by the coupling of major geological events provide not only a prerequisite for massive hydrocarbon generation but also abundant hydrocarbon storage space.The Ordovician-Silurian Wufeng-Longmaxi shale of the Sichuan Basin,Devonian Marcellus shale of the Appalachian Basin,Devonian-Carboniferous Bakken Formation of the Williston Basin,and Triassic Yanchang Formation of the Ordos Basin are four typical unconventional hydrocarbon systems selected as case studies herein.In each case,the formation of sweet-spot intervals for unconventional hydrocarbon resources was controlled by the coupled sedimentation of different global or regional geological events,collectively resulting in a favorable environment for the production,preservation,and accumulation of organic matter,as well as for the generation,migration,accumulation,and exploitation of hydrocarbons.Unconventional petroleum sedimentology,which focuses on coupled sedimentation during dramatic environmental changes driven by major geological events,is key to improve the understanding of the formation and distribution of sweet-spot intervals(areas)in unconventional petroleum systems.
基金Project supported by the National Natural Science Foundation of China(Nos.12172204,11772182,11272193,and 10872121)the Program of Shanghai Municipal Education Commission(No.2019-01-07-00-09-E00018)the Natural Science Foundation of Shanghai(No.22Z00142)。
文摘DNA-based biosensors have played a huge role in many areas,especially in current global coronavirus outbreak.However,there is a great difficulty in the characterization of piezoelectric and flexoelectric coefficients of the nanoscale DNA film,because the existing experimental methods for hard materials are almost invalid.In addition,the relevant theoretical models for DNA films only consider a single effect without clarifying the difference between the two electromechanical effects on device detection signals.This work aims to present multiscale models for DNA-microcantilever experiments to clarify the competitive mechanism in piezoelectric and flexoelectric effects of DNA films on detection signals.First,a Poisson-Boltzmann(PB)equation is used to predict the potential distribution due to the competition between fixed phosphate groups and mobile salt ions in DNA films.Second,a macroscopic piezoelectric/flexoelectric constitutive equation of the DNA film and a mesoscopic free energy model of the DNA solution are combined to analytically predict the electromechanical coefficients of the DNA film and the relevant microcantilever signals by the deformation equivalent method and Zhang’s two-variable method.Finally,the effects of detection conditions on microscopic interactions,electromechanical coupling coefficients,and deflection signals are studied.Numerical results not only agree well with the experimental observations,but also reveal that the piezoelectric and flexoelectric effects of the DNA film should be equivalently modeled when interpreting microcantilever detection signals.These insights might provide opportunities for the microcantilever biosensor with high sensitivity.
基金Project supported by the National Natural Science Foundation of China(Nos.12172204,11772182,11272193,and 10872121)the Program of Shanghai Municipal Education Commission(No.2019-01-07-00-09-E00018)the Natural Science Foundation of Shanghai of China(No.22Z00142)。
文摘DNA nanotubes(DNTs)with user-defined shapes and functionalities have potential applications in many fields.So far,compared with numerous experimental studies,there have been only a handful of models on the mechanical properties of such DNTs.This paper aims at presenting a multiscale model to quantify the correlations among the pre-tension states,tensile properties,encapsulation structures of DNTs,and the surrounding factors.First,by combining a statistical worm-like-chain(WLC)model of single DNA deformation and Parsegian's mesoscopic model of DNA liquid crystal free energy,a multiscale tensegrity model is established,and the pre-tension state of DNTs is characterized theoretically for the first time.Then,by using the minimum potential energy principle,the force-extension curve and tensile rigidity of pre-tension DNTs are predicted.Finally,the effects of the encapsulation structure and surrounding factors on the tensile properties of DNTs are studied.The predictions for the tensile behaviors of DNTs can not only reproduce the existing experimental results,but also reveal that the competition of DNA intrachain and interchain interactions in the encapsulation structures determines the pre-tension states of DNTs and their tensile properties.The changes in the pre-tension states and environmental factors make the monotonic or non-monotonic changes in the tensile properties of DNTs under longitudinal loads.
基金Project supported by the National Natural Science Foundation of China(Nos.12172204,11772182,11272193,and 10872121)the Program of Shanghai Municipal Education Commission(No.2019-01-07-00-09-E00018)。
文摘Time-dependent behaviors due to various mismatch strains are very important to the reliability of micro-/nano-devices.This paper aims at presenting an analytical model to study the viscoelastic stress relaxation of the laminated microbeam caused by mismatch strain.Firstly,Zhang’s two-variable method is used to establish a mechanical model for predicting the quasi-static stress relaxation of the laminated microbeam.Secondly,the related analytical solutions are obtained by combining the differential method and the eigenvalue method in the temporal domain.Finally,the influence of the substrateto-film thickness/modulus ratio on the relaxation responses of the laminated microbeam subject to a step load of the mismatch strain is studied.The results show that the present predictions are consistent with the previous theoretical studies.Furthermore,the thickness dependence of stress relaxation time of the laminated microbeam is jointly determined by the intrinsic structural evolution factors and tension-bending coupling state;the stress relaxation time can be controlled by adjusting the substrate-to-film thickness/modulus ratio.
基金supported by the Harris-Galveston Subsidence District (HGSD)the National Science Foundation(NSF) through awards EAR-1242383, DUE-1243582, and OISE1460034
文摘Houston,Texas,is one of the earliest regions to employ continuous GPS technology for land subsidence monitoring.Currently,there are over 200 permanent GPS stations located in the greater Houston area.The need for a consistent and stable reference frame to precisely interpret local ground deformation has become critically important since the 1990s,because of the significant spreading of subsidence.We have established a stable Houston reference frame,designated Houston16,using publicly available GPS observations(>5 years)from 15 Continuously Operating Reference Stations(CORS)located outside of the greater Houston area.Applications of the reference frame in subsidence and faulting studies are demonstrated in this article.Houston16 is aligned in origin and scale with the International GNSS Reference Frame of 2008(IGS08).A 7-parameter method was employed to transform the GPS-derived positional time series from IGS08 to Houston16.The primary product of this study is the seven parameters for transforming Earth-Centered-Earth-Fixed XYZ coordinates from IGS08 to Houston16.The frame stability of Houston16 is approximately 1 mm/year.Houston16 will be updated every few years to mitigate degradation of the frame’s stability with time and to synchronize with future updates of the IGS reference frame.
文摘In the process of my country’s energy transition,the clean energy of hydropower,wind power and photovoltaic power generation has ushered in great development,but due to the randomness and volatility of its output,it has caused a certain waste of clean energy power generation resources.Regarding the purchase and sale of electricity by electricity retailers under the condition of limited clean energy consumption,this paper establishes a quantitative model of clean energy restricted electricity fromthe perspective of power system supply and demand balance.Then it analyzes the source-charge dual uncertain factors in the electricity retailer purchasing and selling scenarios in the mid-to long-term electricity market and the day-ahead market.Through the multi-scenario analysis method,the uncertain clean energy consumption and the user’s power demand are combined to form the electricity retailer’s electricity purchase and sales scene,and the typical scene is obtained by using the hierarchical clustering algorithm.This paper establishes a electricity retailer’s risk decisionmodel for purchasing and selling electricity in themid-and long-term market and reduce-abandonment market,and takes the maximum profit expectation of the electricity retailer frompurchasing and selling electricity as the objective function.At the same time,in themediumand longterm electricity market and the day-ahead market,the electricity retailer’s purchase cost,electricity sales income,deviation assessment cost and electricity purchase and sale risk are considered.The molecular results show that electricity retailers can obtain considerable profits in the reduce-abandonment market by optimizing their own electricity purchase and sales strategies,on the premise of balancing profits and risks.
基金supported by Special fund for scientific innovation strategy-construction of high level Academy of Agriculture Science-Distinguished Scholar(R2020PYJC001).
文摘Swine are regarded as“intermediate hosts”or“mixing vessels”of influenza viruses,capable of generating strains with pandemic potential.From 2020 to 2021,we conducted surveillance on swine H1N2 influenza(swH1N2)viruses in swine farms located in Guangdong,Yunnan,and Guizhou provinces in southern China,as well as Henan and Shandong provinces in northern China.We systematically analyzed the evolution and pathogenicity of swH1N2 isolates,and characterized their replication and transmission abilities.The isolated viruses are quadruple reassortant H1N2 viruses containing genes from pdm/09 H1N1(PB2,PB1,PA and NP genes),triple-reassortant swine(NS gene),Eurasian Avian-like(HA and M genes),and recent human H3N2(NA gene)lineages.The NA,PB2,and NP of SW/188/20 and SW/198/20 show high gene similarities to A/Guangdong/Yue Fang277/2017(H3N2).The HA gene of swH1N2 exhibits a high evolutionary rate.The five swH1N2 isolates replicate efficiently in human,canine,and swine cells,as well as in the turbinate,trachea,and lungs of mice.A/swine/Shandong/198/2020 strain efficiently replicates in the respiratory tract of pigs and effectively transmitted among them.Collectively,these current swH1N2 viruses possess zoonotic potential,highlighting the need for strengthened surveillance of swH1N2 viruses.
基金funded by the National Natural Science Foundation of China(No.41602119)the Type-A Project for Western Youth Scholars of the Chinese Academy of Sciences,Natural Science Foundation of Gansu Province,China(No.18JR3RA396)+1 种基金the Scientific Research and Technological Development Program of CNPC(No.2016B-0302-01)the National Key Basic Research Program of China(No.2017ZX0505001).
文摘In recent years,significant progress in shale gas exploration has been achieved in the Upper Ordovician(Wufeng Formation)–Lower Silurian(Longmaxi Formation)shales in the Upper Yangtze area,South China.Although many studies have been carried out on the Upper Ordovician–Lower Silurian shales,the controlling factors causing organic matter accumulation of these shales remain controversial.This study uses trace-element geochemistry and sedimentological methods to evaluate terrigenous input,redox conditions and primary productivity to explore the mechanisms of organic matter accumulation.The variation of terrigenous fraction elements(Al,Th and Sc)concentrations reflect a mixed influence of sea-level change and weathering.The sea-level of the Upper Yangtze Sea went through two cycles of transgression to regression during the Ordovician–Silurian transition.The Linxiang Formation,Kuanyinchiao Bed and the upper part of Longmaxi Formation developed during the periods of regression,whereas the Wufeng Formation and the lower part of the Longmaxi Formation developed during the periods of transgression.The paleo-productivity indexes of TOC content,ratios of Ba/Al and P/Al,and redox conditions proxies of Mo concentration,ratios of U/Th and V/Cr generally display similar variation patterns with respect to the sea-level changes.High TOC contents and Ba/Al and P/Al ratios indicate the paleo-productivity was high on the sea surface,as shown by relatively good positive correlations between Th vs.TOC,and Sc vs.TOC.This indicates that the paleo-productivity was controlled by the nutrients input through weathering.The good positive correlations between redox conditions indexes(U/Th and V/Cr ratios)with TOC content reflects reductive preservation conditions(anoxic to euxinic),thus implying they were an important controlling factor for organic matter accumulation.Nevertheless,redox conditions were closely associated with sea level change and organic matter decomposition.Therefore,the sea-level change and weathering were the primary controlling factors for organic matter enrichment across the Ordovician to Silurian transition.
基金supported by the Petro China Science and Technology Project (No.2021DJ18)National Special Program for High-Level Talents (the fourth batch)the PetroChina,national ministries,academical universities and research institutes。
文摘0 INTRODUCTION The breakthroughs in unconventional petroleum have a great impact on world petroleum industry and innovation in petroleum geology(Dou et al,2022;Jia,2017;Zou et al.,2015b,2014a;Yerkin,2012;Pollastro,2007;Schmoker,1995).The exploration and development evolution from conventional petroleum to unconventional petroleum and more and more frequent industrial activities of exploring petroleum inside sources kitchen have deepened theoretical understanding of unconventional petroleum geology and promoted technical research and development(Jia et al.,2021,2017;Jin et al.,2021;Zhao W Z et al.,2020;Ma Y S et al.,2018,2012;Zou et al.,2018b,2016,2009;Dai et al.,2012).We have introduced and extended the theory of continuous hydrocarbon accumulation since 2008 and published several papers/books(in Chinese and English)with respect to unconventional petroleum geology since 2009,basically forming the theoretical framework for this discipline(Yang et al.,2022a,2021a,2019a,,2015a;Zou et al.,2019c,2017b,2014a,,2013a).In this paper,we present the background of unconventional petroleum geology,review the latest theoretical and technological progress in unconventional petroleum geology,introduce relevant thinking and practices in China,and explore the pathway of unconventional petroleum revolution and multi-energy coordinated development in super energy basins,hopefully to promote the unconventional petroleum geology and industry development.
基金funded by the National Natural Science Foundation of China(Grant Nos.41902151,42172180,41830431,and 41902144)the Petro China Scientific Research and Technology Development Project(Grant No.2021DJ1802)。
文摘Mid-high maturity shale oil is the most realistic field for the scale breakthrough of terrestrial shale oil production in China.Generally,three deficiencies hinder shale oil development in China:heavy oil density,small sweet spot areas,and poor distribution continuity.Thus,identifying the“sweet spots”in shale oil reservoirs is critical for the efficient exploration and development of terrestrial shale oil.This study targets the siltstone type(Class-Ⅱshale oil)and pure shale type(Class-Ⅲshale oil)of the Chang 7 Member in the Ordos Basin,and identifies three stratigraphic units,namely the hydrocarbon accumulation unit,hydrocarbon generation unit,and hydrocarbon retention unit,which together constitute the in-source“shale oil system”.The hydrocarbon accumulation unit is mainly siltstone,where the hydrocarbons are migrated from shales.It has favorable porethroat network connectivity with a pore connectivity ratio of 32–57%,being the siltstone-type sweet spots.The hydrocarbon generation unit is mainly composed of high-TOC mudstone/shale and is the main contributor to in-source hydrocarbon generation and expulsion.This unit has high three-dimensional connectivity(28–30%),as shown by the pore-throat network model,associated with vertical paths for hydrocarbon expulsion.The hydrocarbon retention unit is mainly composed of low-TOC mudstone/shale retaining self-generated and migrated hydrocarbons.The pore connectivity rate is 17–42%,and the pore-throat network connectivity direction is uneven.Light and low-carbon-number hydrocarbons are preferentially trapped or even sealed in small pores of the retention unit,forming the typical mudstone/shale-type sweet spots.In the process called shale oil intrasource migration,the oil migrates in source rocks causing component fractionation,which allows more shale oil to enrich in the hydrocarbon accumulation and retention units to form sweet spots,compared with the hydrocarbon generation unit.The migration paths include the one from mudstone/shale to siltstone interlayers and that from the high-TOC mudstone/shale intervals to the low-TOC intervals.The in-source accumulation of shale oil shows the differentiated enrichment model featuring“high-TOC mudstone/shale generating hydrocarbons,low-TOC mudstone/shale retaining hydrocarbons,siltstone accumulating hydrocarbons and multiple intra-source migration paths”.In the Ordos Basin,the organic-lean(TOC 1–3%)mudstone/shale intervals appear to be the sweet spots of shale oil,where there are abundant medium-short-chain hydrocarbons retained with high flowability.After fracturing stimulation,their production conditions may be even superior to those of siltstones.This proposed idea changes the previous strategy to look for sweet spots in high-TOC intervals derived from the shale gas industry.
基金Financial supports from the National Natural Science Foundation of China(Grant Nos.21776308,21908245,and 52022109the Science Foundation of China University of Petroleum,Beijing(Grant Nos.2462018YJRC009 and ZX20200094)the Beijing Municipal Natural Science Foundation(Grant No.2202047)are acknowledged.
文摘Considering its rapid lithiation/delithiation process and robust capacitive energy storage,hierarchical porous carbon is regarded as a promising candidate for lithium-ion batteries(LIBs).However,it remains a great challenge to construct a porous structure and prevent structure stacking for carbon-based materials.Herein,a templatemediated approach is developed to synthesize hierarchical nitrogen-sulfur co-doped porous carbon(NSPC)using low-cost asphalt precursors.The strategy for synthesis uses g-C_(3)N_(4) and NaHCO_(3) as gaseous templates and NaCl as a solid template,which causes the formation of hierarchical porous carbon with a high specific surface area.The resultant porous structure and nitrogen-doping process can prevent the aggregation of nanosheets,maintain the structural stability upon cycling,and achieve rate-capable lithium storage.Serving as a LIBs anode,reversible specific capacities of the NSPC24 electrode reach 788 and 280 mAh·g^(-1) at 0.1 and 1 A·g^(-1),respectively.Furthermore,its specific capacity remains at 830 mAh·g^(-1) after 115 cycles at 0.1 A·g^(-1).Even after 500 cycles,high specific capacities of 727 mAh·g^(-1) at 0.5 A·g^(-1) and 624 mAh·g^(-1) at 1 A·g^(-1) are achieved,demonstrating excellent cycling performance.The gas-solid bifunctional template-mediated approach can guide the design of porous materials very well,meanwhile realizing the high value-added utilization of asphalt.
