The Gulong shale demonstrates high clay content and pronounced thin laminations,with limited vertical variability in log curves,complicating lithofacies classification.To comprehend the distribution and compositional ...The Gulong shale demonstrates high clay content and pronounced thin laminations,with limited vertical variability in log curves,complicating lithofacies classification.To comprehend the distribution and compositional features of lithofacies in the Gulong shale for optimal sweet spot selection and reservoir stimulation,this study introduced a lithofacies classification scheme and a log-based lithofacies evaluation method.Specifically,theΔlgR method was utilized for accurately determining the total organic carbon(TOC)content;a multi-mineral model based on element-to-mineral content conversion coefficients was developed to enhance mineral composition prediction accuracy,and the microresistivity curve variations derived from formation micro-image(FMI)log were used to compute lamination density,offering insights into sedimentary structures.Using this method,integrating TOC content,sedimentary structures,and mineral compositions,the Qingshankou Formation is classified into four lithofacies and 12 sublithofacies,displaying 90.6%accuracy compared to core description outcomes.The classification results reveal that the northern portion of the study area exhibits more prevalent fissile felsic shales,siltstone interlayers,shell limestones,and dolomites.Vertically,the upper section primarily exhibits organic-rich felsic shale and siltstone interlayers,the middle part is characterized by moderate organic quartz-feldspathic shale and siltstone/carbonate interlayers,and the lower section predominantly features organic-rich fissile felsic/clayey felsic shales.Analyzing various sublithofacies in relation to seven petrophysical parameters,oil test production,and fracturing operation conditions indicates that the organic-rich felsic shales in the upper section and the organic-rich/clayey felsic shales in the lower section possess superior physical properties and oil content,contributing to smoother fracturing operation and enhanced production,thus emerging as dominant sublithofacies.Conversely,thin interlayers such as siltstones and limestones,while producing oil,demonstrate higher brittleness and pose great fracturing operation challenges.The methodology and insights in this study will provide a valuable guide for sweet spot identification and horizontal well-based exploitation of the Gulong shale.展开更多
In near-field communication(NFC)antennas,soft magnetic ferrites are usually applied as a substrate to reduce eddy current loss and increase magnetic field coupling.For this purpose,the applied ferrites are required to...In near-field communication(NFC)antennas,soft magnetic ferrites are usually applied as a substrate to reduce eddy current loss and increase magnetic field coupling.For this purpose,the applied ferrites are required to have high permeability and saturation magnetization together with low magnetic loss and dielectric loss.However,for most soft magnetic ferrites,it is difficult to meet all the requirements.Herein novel Ni-Zn ferrite ceramics co-doped by Ho^(3+)and Co^(2+)ions with chemical formula Ni_(0.5-x)Zn_(0.5)Ho_(0.02)Co_(x)Fe_(1.98)O_(4)(x=0-0.2)were designed and prepared to balance these needs on the basis of molten salt synthesis with metal nitrates as raw materials and potassium hydroxide(KOH)as the precipitation agent and molten salt precursor.After the substitution of Ho^(3+),the saturation magnetization and initial permeability decrease,but with further doping of Co^(2+),the saturation magnetization gradually increases,while the initial permeability continues to decrease.When x=0.1,the sample will have the lowest dielectric constant,magnetic and dielectric loss,as well as the highest Curie temperature(305℃).Moreover,the acquired Ni-Zn ferrites have been applied simulatively in NFC antennas,revealing that the device manufactured with the optimal Ni_(0.4)Zn_(0.5)Ho_(0.02)Co_(0.1)Fe_(1.98)O_(4)ferrite ceramics would have significantly improved performance at 13.56 MHz with low leakage and long transmit distance of magnetic field.Therefore,the Ni_(0.4)Zn_(0.5)Ho_(0.02)Co_(0.1)Fe_(1.98)O_(4)ferrite ceramics would be a good candidate for NFC antenna substrates.展开更多
Owing to the robust Li-ion storage properties induced by entropy stabilization effect,transition metal(TM)-based high-entropy oxides(HEOs)are promising electrode materials for highperformance Li-ion batteries(LIBs).In...Owing to the robust Li-ion storage properties induced by entropy stabilization effect,transition metal(TM)-based high-entropy oxides(HEOs)are promising electrode materials for highperformance Li-ion batteries(LIBs).In this study,a six-component Zn_(0.5)Co_(0.5)Mn_(0.5)Fe_(0.5)Al_(0.5)Mg_(0.5)O_(4) spinel-structured HEO(denoted as 6M-HEO,where M=Zn,Co,Mn,Fe,Al,and Mg)was synthesized using a facile coprecipitation method.When used as an anode of the LIBs,its stable high-entropy nanostructures exhibit high specific capacity(290 mAh·g^(−1) at a current density of 2 A·g^(−1)),ultra-long cycling stability(maintained 81%of the initial capacity after 5000 cycles),and outstanding rate performance.Such excellent performance can be attributed to two factors.Firstly,its high-entropy structure can reduce the stress caused by intercalation and avoid volume expansion of the HEO nanostructures.As a result,the cyclic stability was significantly enhanced.Secondly,owing to the unique element selection in this study,four active elements(Zn,Co,Mn,and Fe)were incorporated in inactive MgO and Al2O3 matrice after the first discharge process,which would allow such high-entropy materials to withstand the rapid shuttle of Li ions.展开更多
Rare-earth(RE)doping can greatly enhance the voltage gradient of ZnO-based varistors,and their nonlinear coefficient,leakage current,energy absorption capability,through-current capability and residual voltage can als...Rare-earth(RE)doping can greatly enhance the voltage gradient of ZnO-based varistors,and their nonlinear coefficient,leakage current,energy absorption capability,through-current capability and residual voltage can also be improved to certain extent.In this review,the progress on RE-doped ZnO-based varistor materials in recent years was summarized.The mechanism of RE doping on the electrical performance of ZnO varistors was analyzed.The issues in exploring new ZnO-based varistor materials by RE doping were indicated,and the development trends in this area were proposed.展开更多
基金research is funded by China Petroleum Major Science and Tech-nology Project-Study on Reservoir Formation Theory and Key technology of Gulong Shale Oil(2021ZZ10-01)Petrochina Oil and Gas major project-Research on Production and exploration and development technology of large-scale Increase of Continental shale oil storage(2023ZZ15-02).
文摘The Gulong shale demonstrates high clay content and pronounced thin laminations,with limited vertical variability in log curves,complicating lithofacies classification.To comprehend the distribution and compositional features of lithofacies in the Gulong shale for optimal sweet spot selection and reservoir stimulation,this study introduced a lithofacies classification scheme and a log-based lithofacies evaluation method.Specifically,theΔlgR method was utilized for accurately determining the total organic carbon(TOC)content;a multi-mineral model based on element-to-mineral content conversion coefficients was developed to enhance mineral composition prediction accuracy,and the microresistivity curve variations derived from formation micro-image(FMI)log were used to compute lamination density,offering insights into sedimentary structures.Using this method,integrating TOC content,sedimentary structures,and mineral compositions,the Qingshankou Formation is classified into four lithofacies and 12 sublithofacies,displaying 90.6%accuracy compared to core description outcomes.The classification results reveal that the northern portion of the study area exhibits more prevalent fissile felsic shales,siltstone interlayers,shell limestones,and dolomites.Vertically,the upper section primarily exhibits organic-rich felsic shale and siltstone interlayers,the middle part is characterized by moderate organic quartz-feldspathic shale and siltstone/carbonate interlayers,and the lower section predominantly features organic-rich fissile felsic/clayey felsic shales.Analyzing various sublithofacies in relation to seven petrophysical parameters,oil test production,and fracturing operation conditions indicates that the organic-rich felsic shales in the upper section and the organic-rich/clayey felsic shales in the lower section possess superior physical properties and oil content,contributing to smoother fracturing operation and enhanced production,thus emerging as dominant sublithofacies.Conversely,thin interlayers such as siltstones and limestones,while producing oil,demonstrate higher brittleness and pose great fracturing operation challenges.The methodology and insights in this study will provide a valuable guide for sweet spot identification and horizontal well-based exploitation of the Gulong shale.
基金This work was supported by the National Natural Science Foundation of China(Nos.11674035 and 61274015)the Fundamental Research Funds for the Central Universities.
文摘In near-field communication(NFC)antennas,soft magnetic ferrites are usually applied as a substrate to reduce eddy current loss and increase magnetic field coupling.For this purpose,the applied ferrites are required to have high permeability and saturation magnetization together with low magnetic loss and dielectric loss.However,for most soft magnetic ferrites,it is difficult to meet all the requirements.Herein novel Ni-Zn ferrite ceramics co-doped by Ho^(3+)and Co^(2+)ions with chemical formula Ni_(0.5-x)Zn_(0.5)Ho_(0.02)Co_(x)Fe_(1.98)O_(4)(x=0-0.2)were designed and prepared to balance these needs on the basis of molten salt synthesis with metal nitrates as raw materials and potassium hydroxide(KOH)as the precipitation agent and molten salt precursor.After the substitution of Ho^(3+),the saturation magnetization and initial permeability decrease,but with further doping of Co^(2+),the saturation magnetization gradually increases,while the initial permeability continues to decrease.When x=0.1,the sample will have the lowest dielectric constant,magnetic and dielectric loss,as well as the highest Curie temperature(305℃).Moreover,the acquired Ni-Zn ferrites have been applied simulatively in NFC antennas,revealing that the device manufactured with the optimal Ni_(0.4)Zn_(0.5)Ho_(0.02)Co_(0.1)Fe_(1.98)O_(4)ferrite ceramics would have significantly improved performance at 13.56 MHz with low leakage and long transmit distance of magnetic field.Therefore,the Ni_(0.4)Zn_(0.5)Ho_(0.02)Co_(0.1)Fe_(1.98)O_(4)ferrite ceramics would be a good candidate for NFC antenna substrates.
基金supported by the National Natural Science Foundation of China (Grant No.12174035).
文摘Owing to the robust Li-ion storage properties induced by entropy stabilization effect,transition metal(TM)-based high-entropy oxides(HEOs)are promising electrode materials for highperformance Li-ion batteries(LIBs).In this study,a six-component Zn_(0.5)Co_(0.5)Mn_(0.5)Fe_(0.5)Al_(0.5)Mg_(0.5)O_(4) spinel-structured HEO(denoted as 6M-HEO,where M=Zn,Co,Mn,Fe,Al,and Mg)was synthesized using a facile coprecipitation method.When used as an anode of the LIBs,its stable high-entropy nanostructures exhibit high specific capacity(290 mAh·g^(−1) at a current density of 2 A·g^(−1)),ultra-long cycling stability(maintained 81%of the initial capacity after 5000 cycles),and outstanding rate performance.Such excellent performance can be attributed to two factors.Firstly,its high-entropy structure can reduce the stress caused by intercalation and avoid volume expansion of the HEO nanostructures.As a result,the cyclic stability was significantly enhanced.Secondly,owing to the unique element selection in this study,four active elements(Zn,Co,Mn,and Fe)were incorporated in inactive MgO and Al2O3 matrice after the first discharge process,which would allow such high-entropy materials to withstand the rapid shuttle of Li ions.
基金The authors would like to thank the financial support for this work from the National Natural Science Foundation of China(Grant Nos.61274015,11274052 and 51172030),the Transfer and Industrialization Project of Sci-Tech Achievement(Cooperation Project between University and Factory)from Beijing Municipal Commission of Education,and the Excellent Adviser Foundation in China University of Geosciences from the Fundamental Research Funds for the Central Universities.
文摘Rare-earth(RE)doping can greatly enhance the voltage gradient of ZnO-based varistors,and their nonlinear coefficient,leakage current,energy absorption capability,through-current capability and residual voltage can also be improved to certain extent.In this review,the progress on RE-doped ZnO-based varistor materials in recent years was summarized.The mechanism of RE doping on the electrical performance of ZnO varistors was analyzed.The issues in exploring new ZnO-based varistor materials by RE doping were indicated,and the development trends in this area were proposed.
