Exploring highly efficient and non-noble-metal-based electrocatalysts for oxygen evolution reaction(OER)is of great importance not only for water splitting but also for rechargeable metal-air batteries and fuel cells....Exploring highly efficient and non-noble-metal-based electrocatalysts for oxygen evolution reaction(OER)is of great importance not only for water splitting but also for rechargeable metal-air batteries and fuel cells.Herein,we describe a simple strategy to prepare hierarchical Ni@Mn-doped Ni O hybrids using flower-like Ni-Mn layered double hydroxides(Ni Mn-LDHs)as a precursor.After calcination at 400℃for an hour under N_(2)atmosphere,the flower-like Ni Mn-LDHs transform to porous microspheres consisting of nanoparticles,in which Ni cores are encapsulated by Mn-doped NiO shells(denoted as Ni@MnNi O-400).Benefiting to this unique porous,core-shell structures and element doping,the as-prepared Ni@Mn-NiO-400 hybrid shows a low overpotential of 178 mV at the current density of 10 mA/cm^(2)and Tafel slope of 52.7 m V/dec in 1 mol/L KOH solution.More significantly,the Ni@Mn-Ni O-400 hybrid also demonstrates superior stability of 98.6%after 50 h continuously testing,much higher than pristine Ni MnLDHs and commercial IrO_(2)catalyst.In addition,theoretical simulation shows that Ni core and Mn doping greatly affect the electronic states and electronic structure of Ni O.As a result,Ni@Mn-doped Ni O hybrid possesses an optimal adsorption activity towards oxygen species than Ni O and undoped Ni@Ni O hybrid.Considering the compositional and structural flexibility of LDHs,this work may offer a simple method to prepare other non-noble metal-based electrocatalysts for OER.展开更多
Understanding the thermo-mechanical behavior of various rock types is important in a wide range of geoscientific applications.In this study,the effects of elevated temperature treatments(250℃-750℃)on the elastic res...Understanding the thermo-mechanical behavior of various rock types is important in a wide range of geoscientific applications.In this study,the effects of elevated temperature treatments(250℃-750℃)on the elastic response(wave velocities and mechanical properties)of dolerite,retrieved from a borehole in the Sonhat Basin,India,were analyzed.The results showed that uniaxial compressive strength(UCS)increased by 15.4%at 250℃ compared to their room temperature(25℃)counterparts due to drying effects and inherent rock strengthening,but declined steadily at higher temperatures due to heat-induced microcracking and mineral transformations.Similarly,Young's modulus of the rock samples increased up to 250℃ and then decreased sharply above 450℃,aligning with the brittle-ductile transition temperature of 450℃.Petrographic and electron microscopy analyses of the samples revealed the development of intergranular and intragranular fractures at temperatures above 450℃,contributing to the observed mechanical weakening.Furthermore,ultrasonic wave velocities(P-and S-waves)exhibited significant reductions with increasing temperature,highlighting microstructural damage.These findings provide critical knowledge for designing underground geological engineering structures by identifying temperature thresholds and understanding mechanical degradation under thermal stress.The findings are particularly relevant for underground coal gasification(UCG)projects in the Sonhat Coalfield,where dolerite sills overlying coal seams may be exposed to significant heat.The identified threshold temperatures and trends in mechanical behaviour provide valuable insights for addressing structural stability challenges and mitigating environmental risks,such as surface subsidence.展开更多
Nowadays, the yearning for microwave absorption materials(MAMs) are more and more urgent for dealing with the increasingly serious electromagnetic pollution and the demand of modern military security.Among potential c...Nowadays, the yearning for microwave absorption materials(MAMs) are more and more urgent for dealing with the increasingly serious electromagnetic pollution and the demand of modern military security.Among potential candidates, the graphene(GE) based magnetic hybrids have advantages in structural controllable and designing flexibility, providing opportunities for achieving highly efficiency of microwave absorption(MA). Thus, the structural regulation and MA performances of GE-based magnetic hybrids arouse great attention in related fields. In this review, we summarize the recently progress in MA performance of GE-based magnetic hybrids. Typical absorption process and corresponding mechanism are firstly introduced, for guiding the design of GE-based magnetic MAMs. Then, the magnetic components, synthesis methods, structural features and regulation strategies of these GE-related magnetic materials are reviewed, and their influences on MA performances have also been discussed. Challenges, and prospects of the GE-based magnetic MAMs are suggested. This review provides a brief but systematic introduction to GE-based magnetic MAMs, which may pave the way for the design of MAMs with highly efficient MA performances.展开更多
We study the quantum phase transition from a superfluid to a Mott insulator of ultracold atoms in a threedimensional optical lattice with adjustable filling factors.Based on the density-adjustable Bose-Einstein conden...We study the quantum phase transition from a superfluid to a Mott insulator of ultracold atoms in a threedimensional optical lattice with adjustable filling factors.Based on the density-adjustable Bose-Einstein condensate we prepared,the excitation spectrum in the superfluid and the Mott insulator regime is measured with different ensemble-averaged filling factors.We show that for the superfluid phase,the center of the excitation spectrum is positively correlated with the ensemble-averaged filling factor,indicating a higher sound speed of the system.For the Mott insulator phase,the discrete feature of the excitation spectrum becomes less pronounced as the ensemble-averaged filling factor increases,implying that it is harder for the system to enter the Mott insulator regime with higher filling factors.The ability to manipulate the filling factor affords further potential in performing quantum simulation with cold atoms trapped in optical lattices.展开更多
Erratum to:Journal of Thermal Science https://doi.org/10.1007/s11630-025-2140-3 The original article has been corrected.It was written:Sulfur-Free Expanded Graphite/Paraffin Composite Phase Change Materia with High Th...Erratum to:Journal of Thermal Science https://doi.org/10.1007/s11630-025-2140-3 The original article has been corrected.It was written:Sulfur-Free Expanded Graphite/Paraffin Composite Phase Change Materia with High Thermal Conductivity for Lithium-Ion Battery Thermal Management.展开更多
Paraffin(PA)is a common phase change material,which is widely used in battery thermal management systems(BTMS)because of its high latent heat and temperature uniformity,simple system structure,and no increase in batte...Paraffin(PA)is a common phase change material,which is widely used in battery thermal management systems(BTMS)because of its high latent heat and temperature uniformity,simple system structure,and no increase in battery energy consumption.In this work,sulfur-free expanded graphite(EG)is prepared by oxidation intercalation without H2SO4 in the preparation process,which avoids the harm to devices caused by the S element.The sulfur-free EG exhibits a high expanded volume of 324 mL·g^(-1),which can adsorb PA well to prevent leakage.When the mass filling ratio of EG is 5.0%,EG/PA-5.0 composite films show high latent heat of phase transition(253.08 J.g^(-1)),and thermal conductivity(2.56 W·m^(-1)·K^(-1)).EG/PA films are attached to the external surface of the lithium iron phosphate battery for a heat dissipation performance test.When the discharge rate is 1C at room temperature,the surface temperature and maximum temperature difference between temperature measurement points of the battery with EG/PA-5.0 film are 32.1℃and 1.2℃.After charge-discharge at 1C for 100 cycles,the thermal properties of EG/PA remain basically unchanged,and it has good cycle stability.The simulation results are in good agreement with the actual temperature changes of the battery at different discharge rates.This work indicates that sulfur-free EG/PA composite has a good application prospect in BTMS of the power batteries.展开更多
This book is a popular science toy book which presents China's large aircraft the C919 in the form of three-dimensional modeling on paper books.It contains more than 100 aviation facts and over 30 creative interac...This book is a popular science toy book which presents China's large aircraft the C919 in the form of three-dimensional modeling on paper books.It contains more than 100 aviation facts and over 30 creative interactive structures.In a rich interactive form,readers can feel the charm of the C919 up close and in detail,highlighting the history of China's aviation development.展开更多
基金supported by National Natural Science Foundation of China(Nos.51602184 and 21902096)Natural Science Foundation of Shaanxi Province(Nos.2020JM-505 and 2020JM502)the Academic Talent Introduction Program of SUST(No.134080056)。
文摘Exploring highly efficient and non-noble-metal-based electrocatalysts for oxygen evolution reaction(OER)is of great importance not only for water splitting but also for rechargeable metal-air batteries and fuel cells.Herein,we describe a simple strategy to prepare hierarchical Ni@Mn-doped Ni O hybrids using flower-like Ni-Mn layered double hydroxides(Ni Mn-LDHs)as a precursor.After calcination at 400℃for an hour under N_(2)atmosphere,the flower-like Ni Mn-LDHs transform to porous microspheres consisting of nanoparticles,in which Ni cores are encapsulated by Mn-doped NiO shells(denoted as Ni@MnNi O-400).Benefiting to this unique porous,core-shell structures and element doping,the as-prepared Ni@Mn-NiO-400 hybrid shows a low overpotential of 178 mV at the current density of 10 mA/cm^(2)and Tafel slope of 52.7 m V/dec in 1 mol/L KOH solution.More significantly,the Ni@Mn-Ni O-400 hybrid also demonstrates superior stability of 98.6%after 50 h continuously testing,much higher than pristine Ni MnLDHs and commercial IrO_(2)catalyst.In addition,theoretical simulation shows that Ni core and Mn doping greatly affect the electronic states and electronic structure of Ni O.As a result,Ni@Mn-doped Ni O hybrid possesses an optimal adsorption activity towards oxygen species than Ni O and undoped Ni@Ni O hybrid.Considering the compositional and structural flexibility of LDHs,this work may offer a simple method to prepare other non-noble metal-based electrocatalysts for OER.
基金funded by“The Pearl River Talent Recruitment Program”in 2019(Grant No.2019CX01G338)Guangdong Province and Guangdong Provincial Basic and Applied Basic Research Fund Committee(2022A1515240073).
文摘Understanding the thermo-mechanical behavior of various rock types is important in a wide range of geoscientific applications.In this study,the effects of elevated temperature treatments(250℃-750℃)on the elastic response(wave velocities and mechanical properties)of dolerite,retrieved from a borehole in the Sonhat Basin,India,were analyzed.The results showed that uniaxial compressive strength(UCS)increased by 15.4%at 250℃ compared to their room temperature(25℃)counterparts due to drying effects and inherent rock strengthening,but declined steadily at higher temperatures due to heat-induced microcracking and mineral transformations.Similarly,Young's modulus of the rock samples increased up to 250℃ and then decreased sharply above 450℃,aligning with the brittle-ductile transition temperature of 450℃.Petrographic and electron microscopy analyses of the samples revealed the development of intergranular and intragranular fractures at temperatures above 450℃,contributing to the observed mechanical weakening.Furthermore,ultrasonic wave velocities(P-and S-waves)exhibited significant reductions with increasing temperature,highlighting microstructural damage.These findings provide critical knowledge for designing underground geological engineering structures by identifying temperature thresholds and understanding mechanical degradation under thermal stress.The findings are particularly relevant for underground coal gasification(UCG)projects in the Sonhat Coalfield,where dolerite sills overlying coal seams may be exposed to significant heat.The identified threshold temperatures and trends in mechanical behaviour provide valuable insights for addressing structural stability challenges and mitigating environmental risks,such as surface subsidence.
基金financially supported by National Natural Science Foudation of China (Grant No.51573149)the Science and Technology Planning Projects of Sichuan Province (Grant Nos.2020ZDZX0005,2020ZDZX0008)。
文摘Nowadays, the yearning for microwave absorption materials(MAMs) are more and more urgent for dealing with the increasingly serious electromagnetic pollution and the demand of modern military security.Among potential candidates, the graphene(GE) based magnetic hybrids have advantages in structural controllable and designing flexibility, providing opportunities for achieving highly efficiency of microwave absorption(MA). Thus, the structural regulation and MA performances of GE-based magnetic hybrids arouse great attention in related fields. In this review, we summarize the recently progress in MA performance of GE-based magnetic hybrids. Typical absorption process and corresponding mechanism are firstly introduced, for guiding the design of GE-based magnetic MAMs. Then, the magnetic components, synthesis methods, structural features and regulation strategies of these GE-related magnetic materials are reviewed, and their influences on MA performances have also been discussed. Challenges, and prospects of the GE-based magnetic MAMs are suggested. This review provides a brief but systematic introduction to GE-based magnetic MAMs, which may pave the way for the design of MAMs with highly efficient MA performances.
基金Supported by the National Natural Science Foundation of China(Grant Nos.61703025,91736208,1150432&and 11920101004)the National Program on Key Basic Research Project of China(Grant Nos.2016YFA0301501 and 2017YFA0304204).
文摘We study the quantum phase transition from a superfluid to a Mott insulator of ultracold atoms in a threedimensional optical lattice with adjustable filling factors.Based on the density-adjustable Bose-Einstein condensate we prepared,the excitation spectrum in the superfluid and the Mott insulator regime is measured with different ensemble-averaged filling factors.We show that for the superfluid phase,the center of the excitation spectrum is positively correlated with the ensemble-averaged filling factor,indicating a higher sound speed of the system.For the Mott insulator phase,the discrete feature of the excitation spectrum becomes less pronounced as the ensemble-averaged filling factor increases,implying that it is harder for the system to enter the Mott insulator regime with higher filling factors.The ability to manipulate the filling factor affords further potential in performing quantum simulation with cold atoms trapped in optical lattices.
文摘Erratum to:Journal of Thermal Science https://doi.org/10.1007/s11630-025-2140-3 The original article has been corrected.It was written:Sulfur-Free Expanded Graphite/Paraffin Composite Phase Change Materia with High Thermal Conductivity for Lithium-Ion Battery Thermal Management.
基金the financial support of the Scientific Research Program Funded by Shaanxi Provincial Education Department(23JK0354)the National Natural Science Foundation of China(52272302)。
文摘Paraffin(PA)is a common phase change material,which is widely used in battery thermal management systems(BTMS)because of its high latent heat and temperature uniformity,simple system structure,and no increase in battery energy consumption.In this work,sulfur-free expanded graphite(EG)is prepared by oxidation intercalation without H2SO4 in the preparation process,which avoids the harm to devices caused by the S element.The sulfur-free EG exhibits a high expanded volume of 324 mL·g^(-1),which can adsorb PA well to prevent leakage.When the mass filling ratio of EG is 5.0%,EG/PA-5.0 composite films show high latent heat of phase transition(253.08 J.g^(-1)),and thermal conductivity(2.56 W·m^(-1)·K^(-1)).EG/PA films are attached to the external surface of the lithium iron phosphate battery for a heat dissipation performance test.When the discharge rate is 1C at room temperature,the surface temperature and maximum temperature difference between temperature measurement points of the battery with EG/PA-5.0 film are 32.1℃and 1.2℃.After charge-discharge at 1C for 100 cycles,the thermal properties of EG/PA remain basically unchanged,and it has good cycle stability.The simulation results are in good agreement with the actual temperature changes of the battery at different discharge rates.This work indicates that sulfur-free EG/PA composite has a good application prospect in BTMS of the power batteries.
文摘This book is a popular science toy book which presents China's large aircraft the C919 in the form of three-dimensional modeling on paper books.It contains more than 100 aviation facts and over 30 creative interactive structures.In a rich interactive form,readers can feel the charm of the C919 up close and in detail,highlighting the history of China's aviation development.
