High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile industry.Mg can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress aro...High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile industry.Mg can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress arouses the deformation of large integrated die-castings.Herein,the development of non-heat treatment Al alloys is becoming the hot topic.In addition,HPDC contains externally solidified crystals(ESCs),which are detrimental to the mechanical properties of castings.To achieve high strength and toughness of non-heat treatment die-casting Al-Si alloy,we used AlSi9Mn alloy as matrix with the introduction of Zr,Ti,Nb,and Ce.Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation.Our results reveal that the addition of Ti increased ESCs'size and porosity,while the introduction of Nb refined ESCs and decreased porosity.Meanwhile,large-sized Al_3(Zr,Ti)phases formed and degraded the mechanical properties.Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.展开更多
The need to secure environmentally sustainable sources of clean fuel has led to intensive research into the catalytic conversion of CO_(2)into valuable C_(2)+compounds.However,the intrinsically sluggish reduction kine...The need to secure environmentally sustainable sources of clean fuel has led to intensive research into the catalytic conversion of CO_(2)into valuable C_(2)+compounds.However,the intrinsically sluggish reduction kinetics and competing reaction pathways present challenges in achieving high product selectivity and efficiency.Herein,we focus on the transformation of CO_(2)into C_(2)+products,particularly emphasizing advances in non-copper-based catalytic systems,which have emerged as promising alternatives that present unique electronic structures and adsorption properties.Unlike conventional copper catalysts,these systems offer distinct advantages in selectivity and stability,particularly through the modulation of surface defect engineering.We systematically analyze the main reaction pathways leading to C_(2)+products,including ethylene formation and higher hydrocarbon(C_(2)-4)alcohols and oxygenates,while critically assessing the mechanistic insights that differentiate non-copper catalysts from their Cu-based counterparts.By summarizing recent developments,the key challenges,and optimization strategies,we provide a comprehensive overview of how non-copper catalysts can enable efficient and scalable CO_(2)reduction reactions,with an aim of assisting researchers in their design of novel catalysts that may reach industrial applications.展开更多
After the synthesis of two‐dimensional(2D)graphene through mechanical exfoliation in 2004,2D nanomaterials have emerged as efficient catalysts for many types of reactions,including heterogeneous catalysis,due to thei...After the synthesis of two‐dimensional(2D)graphene through mechanical exfoliation in 2004,2D nanomaterials have emerged as efficient catalysts for many types of reactions,including heterogeneous catalysis,due to their distinct physicochemical and electronic properties.This review highlights recent progress in the application of 2D materials for selected heterogeneous thermo‐catalytic reactions,with an emphasis on their role as active catalysts or catalyst supports.The catalytic behavior of 2D materials,either as a catalyst or support,in various heterogeneous catalytic reactions,such as Knoevenagel condensation,Suzuki coupling,oxidative dehydrogenation,hydrogenation of nitroarenes,and oxidative desulfurization,is discussed.Particular attention is given to catalyst design strategies involving 2D materials functionalized with metal‐free active sites,as well as hybrid systems incorporating noble and non‐noble metals,although our primary focus is on metal‐free and structurally tunable 2D catalytic platforms.We conclude our discussion with a perspective on present challenges and future recommendations in this fast‐evolving field based on recent state‐of‐the‐art developments.In addition,we provide a critical perspective on current challenges and suggest future directions for the development of cost‐effective,selective,and durable 2D‐based catalysts.展开更多
Background Oxidative stress(OS)is involved in low female fertility by altering multi-omics such as the transcriptome,miRome,and lncRNome in follicular cells and follicular fluid.However,the mechanism by which OS affec...Background Oxidative stress(OS)is involved in low female fertility by altering multi-omics such as the transcriptome,miRome,and lncRNome in follicular cells and follicular fluid.However,the mechanism by which OS affects multiomics dynamics remains largely unknown.Here,we report that OS induces lncRNome dynamics in sow granulosa cells(sGCs),which is partially dependent on the transcription factor activity of its effector,FoxO1.Results A total of 2,283 putative FoxO recognition elements(FREs)were identified in the promoters of 394 lncRNAs,accounting for 91.20%(394/432)of the lncRNAs regulated by OS.ChIP and reporter assays showed that the effector FoxO1 mediated OS regulation of lncRNA transcription in a transcription factor activity-dependent manner.InsGCs,OS induces the transcription and function(e.g.,apoptosis)of NORSF(non-coding RNA involved in sow fertility),a nuclear lncRNA involved in sGC function via FoxO1.Furthermore,FoxO1 has been identified as a transcriptional activator of NORSF in sGCs that interacts with the FRE motif of its promoter.Meanwhile,OS downregulates the transcription of CYP19A1,which encodes an essential enzyme for estrogen synthesis and 17β-estradiol(E2)release by sGCs via the FoxO1 and NORSF axis.Phenotypically,dysregulation of NORSF transcription caused by 2 novel adjacent transitions in the promoter leads to decreased sow fertility.Conclusion These results suggest a model of OS-stimulated lncRNome dynamics in sGCs and a new signaling pathway of OS that influences sGC function and sow fertility.展开更多
Using the fuzzy cluster analysis and the temperature-salinity(T-S) similarity number analysis of cruise conductivity-temperature-depth(CTD) data in the upper layer(0–300 m) of the northern South China Sea(NSCS), we c...Using the fuzzy cluster analysis and the temperature-salinity(T-S) similarity number analysis of cruise conductivity-temperature-depth(CTD) data in the upper layer(0–300 m) of the northern South China Sea(NSCS), we classify the upper layer water of the NSCS into six water masses: diluted water(D), surface water(SS),the SCS subsurface water mass(U_S), the Pacific Ocean subsurface water mass(U_P), surface-subsurface mixed water(SU) and subsurface-intermediate mixed water(UI). A new stacked stereogram is used to illustrate the water mass distribution, and to examine the source and the distribution of U_P, combining with the sea surface height data and geostrophic current field. The results show that water mass U_P exists in all four seasons with the maximum range in spring and the minimum range in summer. In spring and winter, the U_P intrudes into the Luzon Strait and the southwest of Taiwan Island via the northern Luzon Strait in the form of nonlinear Rossby eddies, and forms a high temperature and high salinity zone east of the Dongsha Islands. In summer, the U_P is sporadically distributed in the study area. In autumn, the U_P is located in the upper 200 m layer east of Hainan Island.展开更多
To facilitate the electrochemical CO_(2) reduction(ECR)to fuels and valuable chemicals,the development of active,low cost,and selective catalysts is crucial.We report a novel ECR catalyst consisting of CuO nanoparticl...To facilitate the electrochemical CO_(2) reduction(ECR)to fuels and valuable chemicals,the development of active,low cost,and selective catalysts is crucial.We report a novel ECR catalyst consisting of CuO nanoparticles with sizes ranging from 1.4 to 3.3 nm anchored on Cu metal‐organic framework(Cu‐MOF)nanosheets obtained through a one‐step facile solvothermal method.The nanocomposites provide multiple sites for efficient ambient ECR,delivering an average C_(2)H_(4) faradaic efficiency(FE)of~50.0%at–1.1 V(referred to the reversible hydrogen electrode)in 0.1 mol/L aqueous KHCO_(3) using a two‐compartment cell,in stark contrast to a C_(2)H_(4) FE of 25.5%and 37.6%over individual CuO and Cu‐MOF respectively,also surpassing most newly reported Cu‐based materials under similar cathodic voltages.The C_(2)H_(4) FE remains at over 45.0%even after 10.0 h of successive polarization.Also,a~7.0 mA cm^(–2) C_(2)H_(4) partial geometric current density and 27.7%half‐cell C_(2)H_(4) power conversion efficiency are achieved.The good electrocatalytic performance can be attributed to the interface between CuO and Cu‐MOF,with accessible metallic moieties and the unique two‐dimensional structure of the Cu‐MOF enhancing the adsorption and activation of CO_(2) molecules.This finding offers a simple avenue to upgrading CO_(2) to value‐added hydrocarbons by rational design of MOF‐based composites.展开更多
Climate change caused by the increasing emission of CO_(2)to the atmosphere has become a global concern.To ameliorate this issue,converting CO_(2)into valuable chemicals is highly desirable,enabling a sustainable low-...Climate change caused by the increasing emission of CO_(2)to the atmosphere has become a global concern.To ameliorate this issue,converting CO_(2)into valuable chemicals is highly desirable,enabling a sustainable low-carbon future.To this end,developing efficient catalytic systems for CO_(2)conversion has sparked intense interests from both academia and industry.Taking advantage of their highly porous structures and unique properties,metal−organic frameworks(MOFs)have shown great potential as heterogeneous catalysts for CO_(2)conversion.Various transformations involving CO_(2)have been accomplished over MOFs-based materials.Here we provide a comprehensive and up-to-date review on recent advances of heterogeneous CO_(2)thermocatalysis using MOFs,highlighting relationships between structures and properties.Special attention is given to the design strategies for improving the catalytic performance of MOFs.Avenues available to enrich the catalytic active sites in MOF structures are stressed and their respective impacts on CO_(2)conversion efficiency are presented.The synergistic effects between each active site within the structure of MOFs and derivatives are discussed.In the end,future perspectives and challenges in CO_(2)conversion by heterogeneous catalysis with MOFs are described.展开更多
To investigate the interaction of the bolt-reinforced rock and the surface support,an analytical model of the convergence-confinement type is proposed,considering the sequential installation of the fully grouted rockb...To investigate the interaction of the bolt-reinforced rock and the surface support,an analytical model of the convergence-confinement type is proposed,considering the sequential installation of the fully grouted rockbolts and the surface support.The rock mass is assumed to be elastic-brittle-plastic material,obeying the linear Mohr-Coulomb criterion or the non-linear Hoek-Brown criterion.According to the strain states of the tunnel wall at bolt and surface support installation and the relative magnitude between the bolt length and the plastic depth during the whole process,six cases are categorized upon solving the problem.Each case is divided into three stages due to the different effects of the active rockbolts and the passive surface support.The fictitious pressure is introduced to quantify the threedimensional(3D)effect of the tunnel face,and thus,the actual physical location along the tunnel axis of the analytical section can be considered.By using the bolt-rock strain compatibility and the rocksurface support displacement compatibility conditions,the solutions of longitudinal tunnel displacement and the reaction pressure of surface support along the tunnel axis are obtained.The proposed analytical solutions are validated by a series of 3D numerical simulations.Extensive parametric studies are conducted to examine the effect of the typical parameters of rockbolts and surface support on the tunnel displacement and the reaction pressure of the surface support under different rock conditions.The results show that the rockbolts are more effective in controlling the tunnel displacement than the surface support,which should be installed as soon as possible with a suitable length.For tunnels excavated in weak rocks or with restricted displacement control requirements,the surface support should also be installed or closed timely with a certain stiffness.The proposed method provides a convenient alternative approach for the optimization of rockbolts and surface support at the preliminary stage of tunnel design.展开更多
The exploration of active and robust electrocatalysts for both the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is the bottleneck to realize the commercialization of rechargeable metal-air batteries...The exploration of active and robust electrocatalysts for both the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is the bottleneck to realize the commercialization of rechargeable metal-air batteries and regenerative fuel cells.Here we report facile synthesis of three-dimensional(3 D)carbon nanotube(CNT)/carbon composites using earth-abundant coal as the carbon source,hydrogen reductant and heteroatom dopant to grow CNTs.The prepared composite featuring 3 D structural merits and multiple active sites can efficiently catalyze both ORR and OER,affording high activity,fast kinetics,and long-term stability.With the additional incorporation of manganese,the developed catalyst afforded a potential difference of 0.80 V between ORR at the half wave potential and OER at a current density of 10 mA cm^(-2).The optimized sample has presented excellent OER performance within a constructed solar-powered water splitting system with continuously generating oxygen bubbles at anode.Notably,it can be further used as a durable air-electrode catalyst in constructed Zn-air battery,delivering an initial discharge/charge voltage gap of 0.73 V,a remained voltaic efficiency of 61.2%after 160 cycles and capability to power LED light for at least 80 h.This study provides an efficient approach for converting traditional energy resource i.e.coal to value-added alternative oxygen electrocatalysts in renewable energy conversion systems.展开更多
Electrochemical CO_(2)reduction(ECR)powered by renewable energy sources provides a sustainable avenue to producing carbon-neutral fuels and chemicals.The design and development of high performance,cost-effective,and s...Electrochemical CO_(2)reduction(ECR)powered by renewable energy sources provides a sustainable avenue to producing carbon-neutral fuels and chemicals.The design and development of high performance,cost-effective,and stable catalysts for ECR remain a focus of intense research.Here,we report a novel electrocatalyst,two-dimensional cadmium-based 1,4-benzenedicarboxylate metal-organic frameworks(Cd-BDC MOFs)which can effectively convert CO_(2)to CO with a faradaic efficiency(FE)of more than80.0%over the voltage range between-0.9 and-1.1 V(versus reversible hydrogen electrode,vs.RHE)in 0.1 mol·L^(-1) CO_(2)-saturated KHCO_(3)solution with an H-type cell,reaching up to 88.9%at-1.0 V(vs.RHE).The performance outperforms commercial CdO and many other MOF-based materials demonstrated in prior literature.The catalytic property can be readily tuned by manipulating synthesis conditions as well as electrolyte type.Especially,high CO FEs exceeding 90.0%can be attained on the Cd-BDC electrode at potentials ranging from-0.16 to-1.06 V(vs.RHE)in 0.5 mol·L^(-1) KHCO_(3)solution by using a gas diffusion electrode cell system.The maximum CO FE approaches~97.6%at-0.26 V(vs.RHE)and the CO partial geometric current density is as high as about 108.1 mA·cm^(-2) at-1.1 V(vs.RHE).This work offers an efficient,low cost,and alternative electrocatalyst for CO_(2)transformation.展开更多
Ex situ characterization techniques in molecular beam epitaxy(MBE)have inherent limitations,such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber.In recent years...Ex situ characterization techniques in molecular beam epitaxy(MBE)have inherent limitations,such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber.In recent years,the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques.These techniques,such as reflection high-energy electron diffraction,scanning tunneling microscopy,and X-ray photoelectron spectroscopy,allow direct observation of film growth processes in real time without exposing the sample to air,hence offering insights into the growth mechanisms of epitaxial films with controlled properties.By combining multiple in situ characterization techniques with MBE,researchers can better understand film growth processes,realizing novel materials with customized properties and extensive applications.This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research.In addition,through further analysis of these techniques regarding their challenges and potential solutions,particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information,we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.展开更多
This study introduces a type of self-developed, GPS-based, simple and cheap Surface Current Experiment(SUCE)drifters designated for observing surface coastal currents. By examining trajectories of six drifters deploye...This study introduces a type of self-developed, GPS-based, simple and cheap Surface Current Experiment(SUCE)drifters designated for observing surface coastal currents. By examining trajectories of six drifters deployed in the Daya Bay and the drifter-derived velocities, we conclude that such drifters are generally capable of capturing the characteristics of wintertime surface coastal currents along the Guangdong coast.展开更多
This study investigates the temperature inversion phenomenon in the Zhujiang(Pearl) River Estuary(ZRE) using hydrological data collected in a summer cruise during July 6–17, 2015. The results suggest that temperature...This study investigates the temperature inversion phenomenon in the Zhujiang(Pearl) River Estuary(ZRE) using hydrological data collected in a summer cruise during July 6–17, 2015. The results suggest that temperature inversion occurred primarily near the salinity front, with an average temperature difference(ΔT) of 0.42°C between the inversion layer and the underlying water. The inversion layer was approximately 4 m thick on average, with an upper boundary at a depth of 1–6 m and a lower boundary at a depth of 3–10 m. Different mechanisms and dynamic processes were responsible for temperature inversion in different parts of the study area.(1) At the salinity front in the west of the ZRE, the measurements collected by CTD(conductivity,temperature, and depth) showed that the low-salinity water mass on the inner side of the front was approximately2°C cooler than the high-salinity water mass on the outer side. Temperature inversion occurred when the cooler low-salinity water overlapped the warmer high-salinity water near the front due to the driving force of the background flow.(2) Inversion layers occurred at the mouth of the Taiping waterway as a result of varying horizontal flow between two different water masses under the effects of tides and runoff.(3) To the southwest of Hong Kong, temperature inversion occurred due to the interaction of upwelling and the salinity front.展开更多
This study focused on the mechanical behavior of a deep-buried tunnel constructed in horizontally layered limestone,and investigated the effect of a new combined rockboltecable support system on the tunnel response.Th...This study focused on the mechanical behavior of a deep-buried tunnel constructed in horizontally layered limestone,and investigated the effect of a new combined rockboltecable support system on the tunnel response.The Yujingshan Tunnel,excavated through a giant karst cave,was used as a case study.Firstly,a multi-objective optimization model for the rockboltecable support was proposed by using fuzzy mathematics and multi-objective comprehensive decision-making principles.Subsequently,the parameters of the surrounding rock were calibrated by comparing the simulation results obtained by the discrete element method(DEM)with the field monitoring data to obtain an optimized support scheme based on the optimization model.Finally,the optimization scheme was applied to the karst cave section,which was divided into the B-and C-shaped sections.The distribution range of the rockboltecable support in the C-shaped section was larger than that in the B-shaped section.The field monitoring results,including tunnel crown settlement,horizontal convergence,and axial force of the rockboltecable system,were analyzed to assess the effectiveness of the optimization scheme.The maximum crown settlement and horizontal convergence were measured to be 25.9 mm and 35 mm,accounting for 0.1%and 0.2%of the tunnel height and span,respectively.Although the C-shaped section had poorer rock properties than the B-shaped section,the crown settlement and horizontal convergence in the C-shaped section ranged from 46%to 97%of those observed in the B-shaped section.The cable axial force in the Bshaped section was approximately 60%of that in the C-shaped section.The axial force in the crown rockbolt was much smaller than that in the sidewall rockbolt.Field monitoring results demonstrated that the optimized scheme effectively controlled the deformation of the layered surrounding rock,ensuring that it remained within a safe range.These results provide valuable references for the design of support systems in deep-buried tunnels situated in layered rock masses.展开更多
In this study, the sectional characteristics of temperature, salinity and density off the central Zhejiang coast were analyzed using three sections of observational data in the spring of 2016. The results are as follo...In this study, the sectional characteristics of temperature, salinity and density off the central Zhejiang coast were analyzed using three sections of observational data in the spring of 2016. The results are as follows:(1) a cold water patch was observed in the middle layer of sections from 10 to 25 m, and a weak upwelling was observed at the upper layer near the central Zhejiang coast;(2) several thermoclines, inverted thermoclines, and haloclines were observed in the survey area;(3) the Taiwan Warm Current Water(TWCW) climbing from the slope towards the survey area affected the thermocline, making it thinner and intensified; however, the TWCW was not strong enough to break through the thermocline to reach the sea surface.展开更多
Purpose–The microseismic monitoring technique has great advantages on identifying the location,extent and the mechanism of damage process occurring in rock mass.This study aims to analyze distribution characteristics...Purpose–The microseismic monitoring technique has great advantages on identifying the location,extent and the mechanism of damage process occurring in rock mass.This study aims to analyze distribution characteristics and the evolution law of excavation damage zone of surrounding rock based on microseismic monitoring data.Design/methodology/approach–In situ test using microseismic monitoring technique is carried out in the large-span transition tunnel of Badaling Great Wall Station of Beijing-Zhangjiakou high-speed railway.An intelligent microseismic monitoring system is built with symmetry monitoring point layout both on the mountain surface and inside the tunnel to achieve three-dimensional and all-round monitoring results.Findings–Microseismic events can be divided into high density area,medium density area and low density area according to the density distribution of microseismic events.The positions where the cumulative distribution frequencies of microseismic events are 60 and 80%are identified as the boundaries between high and medium density areas and between medium and low density areas,respectively.The high density area of microseismic events is regarded as the high excavation damage zone of surrounding rock,which is affected by the grade of surrounding rock and the span of tunnel.The prediction formulas for the depth of high excavation damage zone of surrounding rock at different tunnel positions are given considering these two parameters.The scale of the average moment magnitude parameters of microseismic events is adopted to describe the damage degree of surrounding rock.The strong positive correlation and multistage characteristics between the depth of excavation damage zone and deformation of surrounding rock are revealed.Based on the depth of high excavation damage zone of surrounding rock,the prestressed anchor cable(rod)is designed,and the safety of anchor cable(rod)design parameters is verified by the deformation results of surrounding rock.Originality/value–The research provides a new method to predict the surrounding rock damage zone of large-span tunnel and also provides a reference basis for design parameters of prestressed anchor cable(rod).展开更多
The classification of the springtime water mass has an important influence on the hydrography,regional climate change and fishery in the Taiwan Strait.Based on 58 stations of CTD profiling data collected in the wester...The classification of the springtime water mass has an important influence on the hydrography,regional climate change and fishery in the Taiwan Strait.Based on 58 stations of CTD profiling data collected in the western and southwestern Taiwan Strait during the spring cruise of 2019,we analyze the spatial distributions of temperature(T)and salinity(S)in the investigation area.Then by using the fuzzy cluster method combined with the T-S similarity number,we classify the investigation area into 5 water masses:the Minzhe Coastal Water(MZCW),the Taiwan Strait Mixed Water(TSMW),the South China Sea Surface Water(SCSSW),the South China Sea Subsurface Water(SCSUW)and the Kuroshio Branch Water(KBW).The MZCW appears in the near surface layer along the western coast of Taiwan Strait,showing low-salinity(<32.0)tongues near the Minjiang River Estuary and the Xiamen Bay mouth.The TSMW covers most upper layer of the investigation area.The SCSSW is mainly distributed in the upper layer of the southwestern Taiwan Strait,beneath which is the SCSUW.The KBW is a high temperature(core value of 26.36℃)and high salinity(core value of 34.62)water mass located southeast of the Taiwan Bank and partially in the central Taiwan Strait.展开更多
The high energy density of green synthetic liquid chemicals and fuels makes them ideal for sustainable energy storage and transportation applications.Electroreduction of carbon dioxide(CO_(2))directly into such high v...The high energy density of green synthetic liquid chemicals and fuels makes them ideal for sustainable energy storage and transportation applications.Electroreduction of carbon dioxide(CO_(2))directly into such high value-added chemicals can help us achieve a renewable C cycle.Such electrochemical reduction typically suffers from low faradaic efficiencies(FEs)and generates a mixture of products due to the complexity of controlling the reaction selectivity.This perspective summarizes recent advances in the mechanistic understanding of CO_(2) reduction reaction pathways toward liquid products and the state-of-the-art catalytic materials for conversion of CO_(2) to liquid C1(e.g.,formic acid,methanol)and C2+products(e.g.,acetic acid,ethanol,n-propanol).Many liquid fuels are being produced with FEs between 80%and 100%.We discuss the use of structure-binding energy relationships,computational screening,and machine learning to identify promising candidates for experimental validation.Finally,we classify strategies for controlling catalyst selectivity and summarize breakthroughs,prospects,and challenges in electrocatalytic CO_(2) reduction to guide future developments.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52175284 and 52474396)the National Key Research and Development Program of China(No.2022YFB3404201)。
文摘High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile industry.Mg can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress arouses the deformation of large integrated die-castings.Herein,the development of non-heat treatment Al alloys is becoming the hot topic.In addition,HPDC contains externally solidified crystals(ESCs),which are detrimental to the mechanical properties of castings.To achieve high strength and toughness of non-heat treatment die-casting Al-Si alloy,we used AlSi9Mn alloy as matrix with the introduction of Zr,Ti,Nb,and Ce.Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation.Our results reveal that the addition of Ti increased ESCs'size and porosity,while the introduction of Nb refined ESCs and decreased porosity.Meanwhile,large-sized Al_3(Zr,Ti)phases formed and degraded the mechanical properties.Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.
基金supported by the Joint Funds of the National Natural Science Foundation of China(U24B20201)National Natural Science Foundation of China(22372007 and 21972010).
文摘The need to secure environmentally sustainable sources of clean fuel has led to intensive research into the catalytic conversion of CO_(2)into valuable C_(2)+compounds.However,the intrinsically sluggish reduction kinetics and competing reaction pathways present challenges in achieving high product selectivity and efficiency.Herein,we focus on the transformation of CO_(2)into C_(2)+products,particularly emphasizing advances in non-copper-based catalytic systems,which have emerged as promising alternatives that present unique electronic structures and adsorption properties.Unlike conventional copper catalysts,these systems offer distinct advantages in selectivity and stability,particularly through the modulation of surface defect engineering.We systematically analyze the main reaction pathways leading to C_(2)+products,including ethylene formation and higher hydrocarbon(C_(2)-4)alcohols and oxygenates,while critically assessing the mechanistic insights that differentiate non-copper catalysts from their Cu-based counterparts.By summarizing recent developments,the key challenges,and optimization strategies,we provide a comprehensive overview of how non-copper catalysts can enable efficient and scalable CO_(2)reduction reactions,with an aim of assisting researchers in their design of novel catalysts that may reach industrial applications.
基金supported by the Joint Funds of the National Natural Science Foundation of China(U24B20201)the National Natural Science Foundation of China(22372007 and 21972010).
文摘After the synthesis of two‐dimensional(2D)graphene through mechanical exfoliation in 2004,2D nanomaterials have emerged as efficient catalysts for many types of reactions,including heterogeneous catalysis,due to their distinct physicochemical and electronic properties.This review highlights recent progress in the application of 2D materials for selected heterogeneous thermo‐catalytic reactions,with an emphasis on their role as active catalysts or catalyst supports.The catalytic behavior of 2D materials,either as a catalyst or support,in various heterogeneous catalytic reactions,such as Knoevenagel condensation,Suzuki coupling,oxidative dehydrogenation,hydrogenation of nitroarenes,and oxidative desulfurization,is discussed.Particular attention is given to catalyst design strategies involving 2D materials functionalized with metal‐free active sites,as well as hybrid systems incorporating noble and non‐noble metals,although our primary focus is on metal‐free and structurally tunable 2D catalytic platforms.We conclude our discussion with a perspective on present challenges and future recommendations in this fast‐evolving field based on recent state‐of‐the‐art developments.In addition,we provide a critical perspective on current challenges and suggest future directions for the development of cost‐effective,selective,and durable 2D‐based catalysts.
基金supported by the National Key R&D Program of China(2022YFD1600903)the National Natural Science Foundation of China(32272842)。
文摘Background Oxidative stress(OS)is involved in low female fertility by altering multi-omics such as the transcriptome,miRome,and lncRNome in follicular cells and follicular fluid.However,the mechanism by which OS affects multiomics dynamics remains largely unknown.Here,we report that OS induces lncRNome dynamics in sow granulosa cells(sGCs),which is partially dependent on the transcription factor activity of its effector,FoxO1.Results A total of 2,283 putative FoxO recognition elements(FREs)were identified in the promoters of 394 lncRNAs,accounting for 91.20%(394/432)of the lncRNAs regulated by OS.ChIP and reporter assays showed that the effector FoxO1 mediated OS regulation of lncRNA transcription in a transcription factor activity-dependent manner.InsGCs,OS induces the transcription and function(e.g.,apoptosis)of NORSF(non-coding RNA involved in sow fertility),a nuclear lncRNA involved in sGC function via FoxO1.Furthermore,FoxO1 has been identified as a transcriptional activator of NORSF in sGCs that interacts with the FRE motif of its promoter.Meanwhile,OS downregulates the transcription of CYP19A1,which encodes an essential enzyme for estrogen synthesis and 17β-estradiol(E2)release by sGCs via the FoxO1 and NORSF axis.Phenotypically,dysregulation of NORSF transcription caused by 2 novel adjacent transitions in the promoter leads to decreased sow fertility.Conclusion These results suggest a model of OS-stimulated lncRNome dynamics in sGCs and a new signaling pathway of OS that influences sGC function and sow fertility.
基金The National Natural Science Foundation of China under contract No.41776027the National Basic Research Program of China under contract Nos 2015CB954004 and 2009CB421208the Open Fund of the Key Laboratory of Ocean Circulation and Waves,Chinese Academy of Sciences under contract No.KLOCW1808
文摘Using the fuzzy cluster analysis and the temperature-salinity(T-S) similarity number analysis of cruise conductivity-temperature-depth(CTD) data in the upper layer(0–300 m) of the northern South China Sea(NSCS), we classify the upper layer water of the NSCS into six water masses: diluted water(D), surface water(SS),the SCS subsurface water mass(U_S), the Pacific Ocean subsurface water mass(U_P), surface-subsurface mixed water(SU) and subsurface-intermediate mixed water(UI). A new stacked stereogram is used to illustrate the water mass distribution, and to examine the source and the distribution of U_P, combining with the sea surface height data and geostrophic current field. The results show that water mass U_P exists in all four seasons with the maximum range in spring and the minimum range in summer. In spring and winter, the U_P intrudes into the Luzon Strait and the southwest of Taiwan Island via the northern Luzon Strait in the form of nonlinear Rossby eddies, and forms a high temperature and high salinity zone east of the Dongsha Islands. In summer, the U_P is sporadically distributed in the study area. In autumn, the U_P is located in the upper 200 m layer east of Hainan Island.
文摘To facilitate the electrochemical CO_(2) reduction(ECR)to fuels and valuable chemicals,the development of active,low cost,and selective catalysts is crucial.We report a novel ECR catalyst consisting of CuO nanoparticles with sizes ranging from 1.4 to 3.3 nm anchored on Cu metal‐organic framework(Cu‐MOF)nanosheets obtained through a one‐step facile solvothermal method.The nanocomposites provide multiple sites for efficient ambient ECR,delivering an average C_(2)H_(4) faradaic efficiency(FE)of~50.0%at–1.1 V(referred to the reversible hydrogen electrode)in 0.1 mol/L aqueous KHCO_(3) using a two‐compartment cell,in stark contrast to a C_(2)H_(4) FE of 25.5%and 37.6%over individual CuO and Cu‐MOF respectively,also surpassing most newly reported Cu‐based materials under similar cathodic voltages.The C_(2)H_(4) FE remains at over 45.0%even after 10.0 h of successive polarization.Also,a~7.0 mA cm^(–2) C_(2)H_(4) partial geometric current density and 27.7%half‐cell C_(2)H_(4) power conversion efficiency are achieved.The good electrocatalytic performance can be attributed to the interface between CuO and Cu‐MOF,with accessible metallic moieties and the unique two‐dimensional structure of the Cu‐MOF enhancing the adsorption and activation of CO_(2) molecules.This finding offers a simple avenue to upgrading CO_(2) to value‐added hydrocarbons by rational design of MOF‐based composites.
文摘Climate change caused by the increasing emission of CO_(2)to the atmosphere has become a global concern.To ameliorate this issue,converting CO_(2)into valuable chemicals is highly desirable,enabling a sustainable low-carbon future.To this end,developing efficient catalytic systems for CO_(2)conversion has sparked intense interests from both academia and industry.Taking advantage of their highly porous structures and unique properties,metal−organic frameworks(MOFs)have shown great potential as heterogeneous catalysts for CO_(2)conversion.Various transformations involving CO_(2)have been accomplished over MOFs-based materials.Here we provide a comprehensive and up-to-date review on recent advances of heterogeneous CO_(2)thermocatalysis using MOFs,highlighting relationships between structures and properties.Special attention is given to the design strategies for improving the catalytic performance of MOFs.Avenues available to enrich the catalytic active sites in MOF structures are stressed and their respective impacts on CO_(2)conversion efficiency are presented.The synergistic effects between each active site within the structure of MOFs and derivatives are discussed.In the end,future perspectives and challenges in CO_(2)conversion by heterogeneous catalysis with MOFs are described.
基金funding support from the Fundamental Research Funds for the Central Universities(Grant No.2023JBZY024)the National Natural Science Foundation of China(Grant Nos.52208382 and 52278387).
文摘To investigate the interaction of the bolt-reinforced rock and the surface support,an analytical model of the convergence-confinement type is proposed,considering the sequential installation of the fully grouted rockbolts and the surface support.The rock mass is assumed to be elastic-brittle-plastic material,obeying the linear Mohr-Coulomb criterion or the non-linear Hoek-Brown criterion.According to the strain states of the tunnel wall at bolt and surface support installation and the relative magnitude between the bolt length and the plastic depth during the whole process,six cases are categorized upon solving the problem.Each case is divided into three stages due to the different effects of the active rockbolts and the passive surface support.The fictitious pressure is introduced to quantify the threedimensional(3D)effect of the tunnel face,and thus,the actual physical location along the tunnel axis of the analytical section can be considered.By using the bolt-rock strain compatibility and the rocksurface support displacement compatibility conditions,the solutions of longitudinal tunnel displacement and the reaction pressure of surface support along the tunnel axis are obtained.The proposed analytical solutions are validated by a series of 3D numerical simulations.Extensive parametric studies are conducted to examine the effect of the typical parameters of rockbolts and surface support on the tunnel displacement and the reaction pressure of the surface support under different rock conditions.The results show that the rockbolts are more effective in controlling the tunnel displacement than the surface support,which should be installed as soon as possible with a suitable length.For tunnels excavated in weak rocks or with restricted displacement control requirements,the surface support should also be installed or closed timely with a certain stiffness.The proposed method provides a convenient alternative approach for the optimization of rockbolts and surface support at the preliminary stage of tunnel design.
基金The financial supports from the National Natural Science Foundation of China(21605067,21763023)Talent Project Grant of the University of Science and Technology Liaoning(601011507-06)Doctoral Start-up Research Funding of the University of Science and Technology Liaoning(USTL010178),China。
文摘The exploration of active and robust electrocatalysts for both the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is the bottleneck to realize the commercialization of rechargeable metal-air batteries and regenerative fuel cells.Here we report facile synthesis of three-dimensional(3 D)carbon nanotube(CNT)/carbon composites using earth-abundant coal as the carbon source,hydrogen reductant and heteroatom dopant to grow CNTs.The prepared composite featuring 3 D structural merits and multiple active sites can efficiently catalyze both ORR and OER,affording high activity,fast kinetics,and long-term stability.With the additional incorporation of manganese,the developed catalyst afforded a potential difference of 0.80 V between ORR at the half wave potential and OER at a current density of 10 mA cm^(-2).The optimized sample has presented excellent OER performance within a constructed solar-powered water splitting system with continuously generating oxygen bubbles at anode.Notably,it can be further used as a durable air-electrode catalyst in constructed Zn-air battery,delivering an initial discharge/charge voltage gap of 0.73 V,a remained voltaic efficiency of 61.2%after 160 cycles and capability to power LED light for at least 80 h.This study provides an efficient approach for converting traditional energy resource i.e.coal to value-added alternative oxygen electrocatalysts in renewable energy conversion systems.
基金supported by the National Natural Science Foundation of China(No.21972010)Beijing Natural Science Foundation(No.2192039)+1 种基金Beijing University of Chemical Technology(XK180301)the Foundation of Key Laboratory of LowCarbon Conversion Science&Engineering,Shanghai Advanced Research Institute,Chinese Academy of Sciences(No.KLLCCSE201901,SARI,CAS)。
文摘Electrochemical CO_(2)reduction(ECR)powered by renewable energy sources provides a sustainable avenue to producing carbon-neutral fuels and chemicals.The design and development of high performance,cost-effective,and stable catalysts for ECR remain a focus of intense research.Here,we report a novel electrocatalyst,two-dimensional cadmium-based 1,4-benzenedicarboxylate metal-organic frameworks(Cd-BDC MOFs)which can effectively convert CO_(2)to CO with a faradaic efficiency(FE)of more than80.0%over the voltage range between-0.9 and-1.1 V(versus reversible hydrogen electrode,vs.RHE)in 0.1 mol·L^(-1) CO_(2)-saturated KHCO_(3)solution with an H-type cell,reaching up to 88.9%at-1.0 V(vs.RHE).The performance outperforms commercial CdO and many other MOF-based materials demonstrated in prior literature.The catalytic property can be readily tuned by manipulating synthesis conditions as well as electrolyte type.Especially,high CO FEs exceeding 90.0%can be attained on the Cd-BDC electrode at potentials ranging from-0.16 to-1.06 V(vs.RHE)in 0.5 mol·L^(-1) KHCO_(3)solution by using a gas diffusion electrode cell system.The maximum CO FE approaches~97.6%at-0.26 V(vs.RHE)and the CO partial geometric current density is as high as about 108.1 mA·cm^(-2) at-1.1 V(vs.RHE).This work offers an efficient,low cost,and alternative electrocatalyst for CO_(2)transformation.
基金supported by the National Key R&D Program of China(Grant No.2021YFB2206503)National Natural Science Foundation of China(Grant No.62274159)+1 种基金CAS Project for Young Scientists in Basic Research(Grant No.YSBR-056)the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant No.XDB43010102).
文摘Ex situ characterization techniques in molecular beam epitaxy(MBE)have inherent limitations,such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber.In recent years,the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques.These techniques,such as reflection high-energy electron diffraction,scanning tunneling microscopy,and X-ray photoelectron spectroscopy,allow direct observation of film growth processes in real time without exposing the sample to air,hence offering insights into the growth mechanisms of epitaxial films with controlled properties.By combining multiple in situ characterization techniques with MBE,researchers can better understand film growth processes,realizing novel materials with customized properties and extensive applications.This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research.In addition,through further analysis of these techniques regarding their challenges and potential solutions,particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information,we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.
基金The National Basic Research Program of China under contract No.2015CB954004the National Natural Science Foundation of China under contract Nos 41606009,41776027,91858201 and 41890801+2 种基金the Xiamen University Fundamental Research Funds for the Central Universities under contract No.20720180099the municipal project of Huizhou City under contract No.F2017-01-1the Laboratory for Regional Oceanography and Numerical Modeling,Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2017A02
文摘This study introduces a type of self-developed, GPS-based, simple and cheap Surface Current Experiment(SUCE)drifters designated for observing surface coastal currents. By examining trajectories of six drifters deployed in the Daya Bay and the drifter-derived velocities, we conclude that such drifters are generally capable of capturing the characteristics of wintertime surface coastal currents along the Guangdong coast.
基金The National Basic Research Program of China under contract No.2015CB954004the National Natural Science Foundation of China under contract Nos 41776027,41606009 and U1405233
文摘This study investigates the temperature inversion phenomenon in the Zhujiang(Pearl) River Estuary(ZRE) using hydrological data collected in a summer cruise during July 6–17, 2015. The results suggest that temperature inversion occurred primarily near the salinity front, with an average temperature difference(ΔT) of 0.42°C between the inversion layer and the underlying water. The inversion layer was approximately 4 m thick on average, with an upper boundary at a depth of 1–6 m and a lower boundary at a depth of 3–10 m. Different mechanisms and dynamic processes were responsible for temperature inversion in different parts of the study area.(1) At the salinity front in the west of the ZRE, the measurements collected by CTD(conductivity,temperature, and depth) showed that the low-salinity water mass on the inner side of the front was approximately2°C cooler than the high-salinity water mass on the outer side. Temperature inversion occurred when the cooler low-salinity water overlapped the warmer high-salinity water near the front due to the driving force of the background flow.(2) Inversion layers occurred at the mouth of the Taiping waterway as a result of varying horizontal flow between two different water masses under the effects of tides and runoff.(3) To the southwest of Hong Kong, temperature inversion occurred due to the interaction of upwelling and the salinity front.
基金supported by the Fundamental Research Funds for the Central Universities (Grant No.2023JBZY024)Beijing Natural Science Foundation (Grant No.9244040)opening Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology (Grant No.SKLGP2023K015).
文摘This study focused on the mechanical behavior of a deep-buried tunnel constructed in horizontally layered limestone,and investigated the effect of a new combined rockboltecable support system on the tunnel response.The Yujingshan Tunnel,excavated through a giant karst cave,was used as a case study.Firstly,a multi-objective optimization model for the rockboltecable support was proposed by using fuzzy mathematics and multi-objective comprehensive decision-making principles.Subsequently,the parameters of the surrounding rock were calibrated by comparing the simulation results obtained by the discrete element method(DEM)with the field monitoring data to obtain an optimized support scheme based on the optimization model.Finally,the optimization scheme was applied to the karst cave section,which was divided into the B-and C-shaped sections.The distribution range of the rockboltecable support in the C-shaped section was larger than that in the B-shaped section.The field monitoring results,including tunnel crown settlement,horizontal convergence,and axial force of the rockboltecable system,were analyzed to assess the effectiveness of the optimization scheme.The maximum crown settlement and horizontal convergence were measured to be 25.9 mm and 35 mm,accounting for 0.1%and 0.2%of the tunnel height and span,respectively.Although the C-shaped section had poorer rock properties than the B-shaped section,the crown settlement and horizontal convergence in the C-shaped section ranged from 46%to 97%of those observed in the B-shaped section.The cable axial force in the Bshaped section was approximately 60%of that in the C-shaped section.The axial force in the crown rockbolt was much smaller than that in the sidewall rockbolt.Field monitoring results demonstrated that the optimized scheme effectively controlled the deformation of the layered surrounding rock,ensuring that it remained within a safe range.These results provide valuable references for the design of support systems in deep-buried tunnels situated in layered rock masses.
基金The National Key R&D Program of China under contract No.2018YFC1406302the National Basic Research Program of China under contract No.2015CB954004the National Natural Science Foundation of China under contract Nos 41230961,U1405233 and 41776027
文摘In this study, the sectional characteristics of temperature, salinity and density off the central Zhejiang coast were analyzed using three sections of observational data in the spring of 2016. The results are as follows:(1) a cold water patch was observed in the middle layer of sections from 10 to 25 m, and a weak upwelling was observed at the upper layer near the central Zhejiang coast;(2) several thermoclines, inverted thermoclines, and haloclines were observed in the survey area;(3) the Taiwan Warm Current Water(TWCW) climbing from the slope towards the survey area affected the thermocline, making it thinner and intensified; however, the TWCW was not strong enough to break through the thermocline to reach the sea surface.
基金supported by the Fundamental Research Funds for Chinese National Natural Science Foundation under Grant 51678035National Key Research and Development Programs of China under Grant 2017YFC0805401China Railway Corporation Research and Development Program of Science and Technology under Grant 2014004-C.
文摘Purpose–The microseismic monitoring technique has great advantages on identifying the location,extent and the mechanism of damage process occurring in rock mass.This study aims to analyze distribution characteristics and the evolution law of excavation damage zone of surrounding rock based on microseismic monitoring data.Design/methodology/approach–In situ test using microseismic monitoring technique is carried out in the large-span transition tunnel of Badaling Great Wall Station of Beijing-Zhangjiakou high-speed railway.An intelligent microseismic monitoring system is built with symmetry monitoring point layout both on the mountain surface and inside the tunnel to achieve three-dimensional and all-round monitoring results.Findings–Microseismic events can be divided into high density area,medium density area and low density area according to the density distribution of microseismic events.The positions where the cumulative distribution frequencies of microseismic events are 60 and 80%are identified as the boundaries between high and medium density areas and between medium and low density areas,respectively.The high density area of microseismic events is regarded as the high excavation damage zone of surrounding rock,which is affected by the grade of surrounding rock and the span of tunnel.The prediction formulas for the depth of high excavation damage zone of surrounding rock at different tunnel positions are given considering these two parameters.The scale of the average moment magnitude parameters of microseismic events is adopted to describe the damage degree of surrounding rock.The strong positive correlation and multistage characteristics between the depth of excavation damage zone and deformation of surrounding rock are revealed.Based on the depth of high excavation damage zone of surrounding rock,the prestressed anchor cable(rod)is designed,and the safety of anchor cable(rod)design parameters is verified by the deformation results of surrounding rock.Originality/value–The research provides a new method to predict the surrounding rock damage zone of large-span tunnel and also provides a reference basis for design parameters of prestressed anchor cable(rod).
基金The National Natural Science Foundation of China under contract Nos 42106005,91958203,41676131,41876155.
文摘The classification of the springtime water mass has an important influence on the hydrography,regional climate change and fishery in the Taiwan Strait.Based on 58 stations of CTD profiling data collected in the western and southwestern Taiwan Strait during the spring cruise of 2019,we analyze the spatial distributions of temperature(T)and salinity(S)in the investigation area.Then by using the fuzzy cluster method combined with the T-S similarity number,we classify the investigation area into 5 water masses:the Minzhe Coastal Water(MZCW),the Taiwan Strait Mixed Water(TSMW),the South China Sea Surface Water(SCSSW),the South China Sea Subsurface Water(SCSUW)and the Kuroshio Branch Water(KBW).The MZCW appears in the near surface layer along the western coast of Taiwan Strait,showing low-salinity(<32.0)tongues near the Minjiang River Estuary and the Xiamen Bay mouth.The TSMW covers most upper layer of the investigation area.The SCSSW is mainly distributed in the upper layer of the southwestern Taiwan Strait,beneath which is the SCSUW.The KBW is a high temperature(core value of 26.36℃)and high salinity(core value of 34.62)water mass located southeast of the Taiwan Bank and partially in the central Taiwan Strait.
基金supported by the Joint Funds of the National Natural Science Foundation of China(U24B20201)National Natural Science Foundation of China(22372007 and 21972010)+1 种基金the Fundamental Research Funds for the Central Universities(JD2427)the SRC Center for Electron Transfer(2021R1A5A1030054)funded by NRF Korea and AI Graduate School Program(RS-2021-II211343).
文摘The high energy density of green synthetic liquid chemicals and fuels makes them ideal for sustainable energy storage and transportation applications.Electroreduction of carbon dioxide(CO_(2))directly into such high value-added chemicals can help us achieve a renewable C cycle.Such electrochemical reduction typically suffers from low faradaic efficiencies(FEs)and generates a mixture of products due to the complexity of controlling the reaction selectivity.This perspective summarizes recent advances in the mechanistic understanding of CO_(2) reduction reaction pathways toward liquid products and the state-of-the-art catalytic materials for conversion of CO_(2) to liquid C1(e.g.,formic acid,methanol)and C2+products(e.g.,acetic acid,ethanol,n-propanol).Many liquid fuels are being produced with FEs between 80%and 100%.We discuss the use of structure-binding energy relationships,computational screening,and machine learning to identify promising candidates for experimental validation.Finally,we classify strategies for controlling catalyst selectivity and summarize breakthroughs,prospects,and challenges in electrocatalytic CO_(2) reduction to guide future developments.
