A natural rutle sample was measured by in situ high-temperature X-ray diffraction(XRD)patterns,as well as Raman and Fourier transform infrared(FTIR).Crystal structure is refined on the sample with 1.4 mol.%Fe and 510&...A natural rutle sample was measured by in situ high-temperature X-ray diffraction(XRD)patterns,as well as Raman and Fourier transform infrared(FTIR).Crystal structure is refined on the sample with 1.4 mol.%Fe and 510±120 ppmw.H2 O.The unit-cell and Ti O6 octahedral volumes are expanded by 0.7%–0.8%for Fe3+incorporation,as compared with the reported Ti-pure samples.The volumetric thermal expansion coefficient(α,K-1)could be approximated as a linear function of T(K):4.95(3)×10-9×T+21.54(5)×10-6,with the averaged valueα0=30.48(5)×10-6 K-1,in the temperature range of 300–1500 K.The internal Ti-O stretching(A1 g and B2 g)and O-Ti-O bending(Eg)modes show‘red shift',whereas the multi-phonon process exhibits‘blue shift'at elevated temperature.The rotational mode(B1 g)for Ti O6 octahedra is nearly insensitive to temperature variations.The OH-stretching bands at 3279 and 3297 cm-1 are measured by high-temperature spectroscopy experiments.Both the IR-active and Raman-active OH-stretching modes shift to lower frequencies at higher temperature,with the signal intensities decreasing.And after quenching,we expect about 43%dehydration around 873 K,and 85%dehydration at 1273 K for this hydrous sample.展开更多
A series of linear stability analysis is carried out on the onset of thermal convection in the presence of spatial variations of viscosity, thermal conductivity and expansivity. We consider the temporal evolution of a...A series of linear stability analysis is carried out on the onset of thermal convection in the presence of spatial variations of viscosity, thermal conductivity and expansivity. We consider the temporal evolution of an infinitesimal perturbation superimposed to a static （motionless） and con- ductive state in a basally-heated planar layer. From the changes in flow patterns with increasing the amplitudes of temperature dependence of viscosity, we identified the transition into the ＂stagnant-lid＂ （ST） regime, where the convection occurs only beneath a thick and stagnant-lid of cold fluid at the top surface. Detailed analysis showed a significant increase of the aspect ratio of convection cells in ST regime induced by the spatial variations in thermal conductivity and/or expansivity： the horizon- tal length scale of ST convection can be enlarged by up to 50% with 10 times increase of thermal conductivity with depth. We further developed an analytical model of ST convection which success- fully reproduced the mechanism of increasing horizontal length scale of ST regime convection cells for given spatial variations in physical properties. Our findings may highlight the essential roles of the spatial variation of thermal conductivity on the convection patterns in the mantle.展开更多
The molar volume isotherms of trans-decahydronaphthalene （C10H18） between 293 and 446 K and at pressures from 10 to 200 MPa have been determined. A modified Tait equation of state is used to fit each experimental mo...The molar volume isotherms of trans-decahydronaphthalene （C10H18） between 293 and 446 K and at pressures from 10 to 200 MPa have been determined. A modified Tait equation of state is used to fit each experimental molar volume isotherm with a maximum average deviation of 0.029%. The thermal expansivity （cubic expansion coefficient） α and isothermal compressibility κ were determined by fitting the slopes of the isobaric curves and isotherms, respectively. The coefficients in the equation Vm=C1＋C2T＋C3T^2-C4p-C5pT have been fitted with an average deviation of 1.03%.展开更多
The unit-cell parameters and volumes of geikielite(MgTiO_(3))and ilmenite(FeTiO_(3))were investigated at high temperatures up to 700 K and ambient pressure,using in-situ angle-dispersive synchrotron X-ray diffraction....The unit-cell parameters and volumes of geikielite(MgTiO_(3))and ilmenite(FeTiO_(3))were investigated at high temperatures up to 700 K and ambient pressure,using in-situ angle-dispersive synchrotron X-ray diffraction.No phase transition was detected over the experimental temperature range.Using(Berman in J Petrol29:445-522,1988.10.1093/petrology/29.2.445)equations to fit the temperature-volume data,the volumetric thermal expansion coefficients at ambient conditions(α_(V0))of MgTiO_(3) and FeTiO_(3) were obtained as follows:2.55(6)×10^(-5)K^(-1)and 2.82(10)×10^(-5)K^(-1),respectively.We infer that the larger effective ionic radius of Fe^(2+)(Ⅵ)(0.78 A)than that of Mg^(2+)(Ⅵ)(0.72?)renders FeTiO_(3)has a larger volumetric thermal expansivity than MgTiO_(3).Simultaneously,the refined axial thermal expansion coefficients under ambient conditions areα_(a0)=0.74(3)×10^(-5)K^(-1)andα_(c0)=1.08(5)×10^(-5)K^(-1)for the aaxis and c-axis of MgTiO_(3),respectively,andα_(a0)=0.95(5)×10^(-5)K^(-1)andα_(c0)=0.92(12)×10^(-5)K^(-1)for the aaxis and c-axis of FeTiO_(3),respectively.The axial thermal expansivity of MgTiO_(3) is anisotropic,but that of FeTiO_(3) is nearly isotropic.We infer that the main reason for the different axial thermal expansivity between MgTiO_(3) and FeTiO_(3) is that the thermal expansion mode of the Mg-O bond in MgTiO_(3) is different from that of the Fe-O bonds in FeTiO_(3).展开更多
Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the...Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.展开更多
High-finesse optical reference cavities are essential tools for fundamental research.In response to China’s historical reliance on importing high-finesse optical reference cavities,we successfully developed a cavity ...High-finesse optical reference cavities are essential tools for fundamental research.In response to China’s historical reliance on importing high-finesse optical reference cavities,we successfully developed a cavity using ultralow expansion glass(ULE)materials and processed it entirely in China.Using the method of measuring the cavity linewidth,a finesse of approximately 480000 was obtained in our experiments.We adopted a relatively simple and effective approach to test the optical reference cavity,which involved measuring the resonant points using an ultrastable laser.Remarkably,an expansion coefficient of the Chinese ULE optical reference cavity reached up to the order of 10^(-9)/K within the temperature range of 27℃to 40℃,with the zero expansion point occurring at approximately 34oC.These findings demonstrate China’s independent capability to develop high-finesse optical reference cavities,which is a significant advancement in precision optics.展开更多
Due to batteries inconsistencies and potential faults in battery management systems,slight overcharging remains a common yet insufficiently understood safety risk,lacking effective warning methods.To illuminate the de...Due to batteries inconsistencies and potential faults in battery management systems,slight overcharging remains a common yet insufficiently understood safety risk,lacking effective warning methods.To illuminate the degradation behavior and failure mechanism of various overcharged states(100%SOC,105%SOC,110%SOC,and 115%SOC),multiple advanced in-situ characterization techniques(accelerating rate calorimeter,electrochemical impedance spectroscopy,ultrasonic scanning,and expansion instrument)were utilized.Additionally,re-overcharge-induced thermal runaway(TR)tests were conducted,with a specific emphasis on the evolution of the expansion force signal.Results indicated significant degradation at 110%SOC including conductivity loss,loss of lithium inventory,and loss of active material accompanied by internal gas generation.These failure behaviors slow down the expansion force rate during reovercharging,reducing the efficacy of active warnings that depend on rate thresholds of expansion force.Specifically,the warning time for 115%SOC battery is only 144 s,which is 740 s shorter than that for fresh battery,and the time to TR is advanced by 9 min.Moreover,the initial self-heating temperature(T1)is reduced by 62.4℃compared to that of fresh battery,reaching only 70.8℃.To address the low safety of overcharged batteries,a passive overcharge warning method utilizing relaxation expansion force was proposed,based on the continued gas generation after stopping charging,leading to a sustained increase in force.Compared to active methods that rely on thresholds of expansion force rate,the passive method can issue warnings 115 s earlier.By combining the passive and active warning methods,guaranteed effective overcharge warning can be issued 863-884 s before TR.This study introduces a novel perspective for enhancing the safety of batteries.展开更多
For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial...For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial quotients.In this paper,we establish the Hausdorff dimension of the exceptional set where the growth rate is a general function.展开更多
As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation ...As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.展开更多
In this paper,we establish common fixed point theorems for expansive map?pings on b-metric-like space and coincidence point for f-weakly isotone increasing mappings in partially ordered b-metric-like space.The main re...In this paper,we establish common fixed point theorems for expansive map?pings on b-metric-like space and coincidence point for f-weakly isotone increasing mappings in partially ordered b-metric-like space.The main results generalize and extend several well-known comparable results from the existing literature.Moreover,some examples are provided to illustrate the main results.展开更多
The expansion of construction land on slopes in mountainous cities like Lanzhou has addressed the shortage of flat land but compromised slope stability,leading to uneven land subsidence and risks to infrastructure.Thi...The expansion of construction land on slopes in mountainous cities like Lanzhou has addressed the shortage of flat land but compromised slope stability,leading to uneven land subsidence and risks to infrastructure.This study assessed the land subsidence before and after urban expansion in five areas of Lanzhou by using slope spectrum construction method and gradient expansion intensity measurement that integrated with SBAS-InSAR technology.The results show that construction land on slopes over 20°increased significantly,accounting for 16%of new construction land.The average slope spectrum index was 4.02,with the upper slope limit rising by 8.2°.The land subsidence rate threshold increased by 10 mm/a,and the proportion of pixels experiencing subsidence greater than 5 mm/year rose from 3.63%to 5.24%.Increased construction intensity on slopes caused higher and faster subsidence,which diminished with greater distance from the expansion areas.Areas with slopes between 10°and 25°saw the greatest acceleration in subsidence.Geological composition,building density,groundwater exploitation,and cut-and-fill thickness collectively influence land subsidence rates.This study provides a scientific basis for mitigating geological disaster risks and promoting safe urban development in mountainous cities.展开更多
Silicon-based materials are considered as the next generation anode to replace graphite due to their low cost and ultra-high theoretical capacity.However,significant volume expansion and contraction occur during charg...Silicon-based materials are considered as the next generation anode to replace graphite due to their low cost and ultra-high theoretical capacity.However,significant volume expansion and contraction occur during charging and discharging processes,leading to the instability of electrode structure and susceptibility to peeling and damage,limiting its application.Constructing controllable molecular artificial solid electrolyte interphase(CMASEI)is an effective approach to address the commercialization of silicon-based anode materials[1].Improving the performance of silicon-based anodes through CMASEI is a multifaceted outcome.展开更多
For the people of Masaka,Kabuga and Muyumbu in Rwanda,the daily commute often takes longer than it should.A stretch of just 10 km along the Prince House-Giporoso-Masaka road can take half an hour during peak hours.The...For the people of Masaka,Kabuga and Muyumbu in Rwanda,the daily commute often takes longer than it should.A stretch of just 10 km along the Prince House-Giporoso-Masaka road can take half an hour during peak hours.The narrow two-lane artery,clogged with long-haul trucks from the Rwanda-Tanzania border and commuter traffic,has long tested the patience of drivers and pedestrians alike.In May,a long-awaited announcement finally arrived.Rwanda’s Ministry of Infrastructure confirmed plans to expand the road from two lanes to four,adding a 1.2-km flyover at Giporoso-Remera and an underpass to keep tra"c flowing smoothly.The$60.5 million(Rwf86 billion)project will be fully funded by China,a testament to the deepening friendship and cooperation between the two nations.For many residents,it signals the end of years of lost time and daily frustration.展开更多
The clinical application of hepatocyte transplantation has been significantly hindered by the scarcity of primary hepatocytes and the functional immaturity of in vitro-pro-duced hepatocytes.By performing serial alloge...The clinical application of hepatocyte transplantation has been significantly hindered by the scarcity of primary hepatocytes and the functional immaturity of in vitro-pro-duced hepatocytes.By performing serial allogeneic hepatocyte transplantation in CRISPR/Cas9-mediated Fah-knockout pigs,we successfully achieved large-scale ex-pansion of hepatocytes while maintaining their authentic biological characteristics.Particularly,the established model enables sustained in vivo liver reconstruction,concurrently ameliorating hepatic fibrosis and demonstrating functional microenvi-ronmental remodeling.Moreover,through comprehensive single-cell transcriptomic profiling of 52418 hepatocytes across transplant generations(F0-F2),we discovered that the cellular composition of these transplanted hepatocytes is similar to that of wild-type hepatocytes.The regenerated liver exhibits all six major hepatic cell types identical to the wild-type counterparts,with the characteristic lobular zonation pat-terns well preserved.Our research provides valuable insights into the large-scale expansion of physiologically functional hepatocytes in vivo without compromising their biological properties.This finding holds great promise for advancing the clinical application of human hepatocyte transplantation,potentially offering more effective treatment options for patients with liver diseases.展开更多
The capacitive deionization(CDI)performance of silver(Ag)electrodes is limited by electrochemical failure induced by volumetric expansion.While carbon encapsulation and Ag size control mitigate stress concentration an...The capacitive deionization(CDI)performance of silver(Ag)electrodes is limited by electrochemical failure induced by volumetric expansion.While carbon encapsulation and Ag size control mitigate stress concentration and pulverization,achieving precise size control,suppression of aggregation,and uniform dispersion of Ag nanoparticles remains challenging.Herein,the metal-organic frameworks(MOF)-assisted pyrolysis-galvanic replacement method was employed to construct ultrafine Ag particles uniformly anchored within a three-dimensional(3D)-ordered porous carbon skeleton composite(3D Ag@NC).By utilizing the potential difference between the elements,spontaneous replacement reactions occur,effectively preventing particle agglomeration usually caused by high-temperature reduction.The in situ constructed 3D porous carbon skeleton not only promotes electron transfer and electrolyte penetration but also mitigates the volume expansion of Ag particles during electrochemical cycling.Consequently,3D Ag@NC demonstrates outstanding dechlorination performance(105.29 mg g^(-1)),high charge efficiency(0.95),and exceptional cycling stability(84.12% after 100 cycles).This galvanic replacement strategy offers valuable insights into the fabrication of other small-sized,highly dispersed metal electrode materials.展开更多
Tissue expansion is a widely utilized technique in plastic and reconstructive surgery;however,the biological mechanisms underlying the skin response remain poorly understood.We propose that tissue fluidity,the transit...Tissue expansion is a widely utilized technique in plastic and reconstructive surgery;however,the biological mechanisms underlying the skin response remain poorly understood.We propose that tissue fluidity,the transition of tissue from a solid-like state to a fluid-like state,plays a pivotal role in enabling the reorganization of the epidermal structure and cellular spatial order,which is essential for effective tissue expansion.Drawing parallels between fluidity in materials science and biological systems,we suggest that the fluid-like behavior in the skin may be critical for mechanical adaptability.Understanding the influence of tissue fluidity may open pathways for modulating this process,potentially enhancing tissue expansion efficiency,reducing procedural duration,and improving clinical outcomes.This perspective highlights the importance of investigating the biological dynamics of tissue fluidity and exploring the potential for targeted manipulation of fluidity-related pathways to optimize tissue expansion.Such advancements could profoundly affect regenerative and reconstructive surgical practices.展开更多
Increasing the hole expansion ratio is significant for developing high formability parts.Hole expansion tests were carried out on low carbon hot-rolled steel containing 0.11%Ti,0.072%Ti–0.03%Nb and 0.097%Ti–0.059%Nb...Increasing the hole expansion ratio is significant for developing high formability parts.Hole expansion tests were carried out on low carbon hot-rolled steel containing 0.11%Ti,0.072%Ti–0.03%Nb and 0.097%Ti–0.059%Nb,respectively.The effects of microstructure,texture,crack propagation behavior and second phase precipitation behavior on hole expansion ratio were investigated.The precipitation behavior of TiC and(Ti,Nb)C in austenite and ferrite in three groups of steel samples was calculated theoretically.The results showed that the hole expansion ratios of 0.11Ti,0.072Ti–0.03Nb and 0.097Ti–0.059Nb test steels were 51.73%,51.17%and 66.24%following simulated coiling at 600℃,respectively.The microstructure was mainly polygonal ferrite with a small amount of pearlite.The grain refinement of 0.097Ti–0.059Nb test steel and the low texture ratio of{110}//ND improved the hole expansion ratio.The low overall hole expansion ratio was due to the microstructure inhomogeneity.The microstructure uniformity was improved by the quenching and tempering treatment,and the hole expansion ratio of the three test steels was greatly increased.The fastest precipitation temperatures in the austenitic region of 0.11Ti,0.072Ti–0.03Nb and 0.097Ti–0.059Nb test steels were 880,860 and 830℃,while those in the ferrite region were 680,675 and 675℃,respectively.The addition of Nb element increased the volume free energy,so that the critical core size of the nucleation on the dislocation line increased,resulting in the decrease in the fastest precipitation temperature.展开更多
Catalytic syntheses of silaoxycarbocyclics from an interrupted Catellani reaction of 3-iodochromones with bridged olefins and octamethyl-1,4-dioxacyclohexasilane is described.This protocol involves the oxidative addit...Catalytic syntheses of silaoxycarbocyclics from an interrupted Catellani reaction of 3-iodochromones with bridged olefins and octamethyl-1,4-dioxacyclohexasilane is described.This protocol involves the oxidative addition of chromonyl-norbornyl-palladacycle generated through successive oxidative addition of Pd(0)to 3-iodochromones,migratory insertion of NBE and intramolecular ortho-C(sp^(2))-H activation to the tetrasilane,thus motivating a(4+6)annulation and ring expansion.The synthetic practicality of current strategy is further proved by the late-stage modification of pharmaceuticals and natural products,gram-scale experiments,as well as the transformations of functional groups of silaoxycarbocyclics.展开更多
While the Trump administration’s new measures mean negative repercussions for the entire world,Chinese AI company DeekSeek’s innovation is a gift for the progress of all.THE United States ending its World Health Org...While the Trump administration’s new measures mean negative repercussions for the entire world,Chinese AI company DeekSeek’s innovation is a gift for the progress of all.THE United States ending its World Health Organization(WHO)membership,rejecting the Paris Climate Agreement,expressing expansionist ambitions over Greenland,Canada,Mexico and Panama,and declaring trade wars in the early days of the new Trump administration contrasts sharply with another disruptive development in another part of the world-the announcement by Chinese artificial intelligence(AI)company DeepSeek that its revolutionary AI model will be open to all.Two antipode disruptions indeed.展开更多
基金the National Key Research and Development Program of China(No.2016YFC0600204)the National Natural Science Foundation of China(Nos.41590621 and 41672041)。
文摘A natural rutle sample was measured by in situ high-temperature X-ray diffraction(XRD)patterns,as well as Raman and Fourier transform infrared(FTIR).Crystal structure is refined on the sample with 1.4 mol.%Fe and 510±120 ppmw.H2 O.The unit-cell and Ti O6 octahedral volumes are expanded by 0.7%–0.8%for Fe3+incorporation,as compared with the reported Ti-pure samples.The volumetric thermal expansion coefficient(α,K-1)could be approximated as a linear function of T(K):4.95(3)×10-9×T+21.54(5)×10-6,with the averaged valueα0=30.48(5)×10-6 K-1,in the temperature range of 300–1500 K.The internal Ti-O stretching(A1 g and B2 g)and O-Ti-O bending(Eg)modes show‘red shift',whereas the multi-phonon process exhibits‘blue shift'at elevated temperature.The rotational mode(B1 g)for Ti O6 octahedra is nearly insensitive to temperature variations.The OH-stretching bands at 3279 and 3297 cm-1 are measured by high-temperature spectroscopy experiments.Both the IR-active and Raman-active OH-stretching modes shift to lower frequencies at higher temperature,with the signal intensities decreasing.And after quenching,we expect about 43%dehydration around 873 K,and 85%dehydration at 1273 K for this hydrous sample.
基金acknowledge thorough support from the Global COE program from the Ministry of Education, Culture, Sports and Technology (MEXT) of Japan
文摘A series of linear stability analysis is carried out on the onset of thermal convection in the presence of spatial variations of viscosity, thermal conductivity and expansivity. We consider the temporal evolution of an infinitesimal perturbation superimposed to a static （motionless） and con- ductive state in a basally-heated planar layer. From the changes in flow patterns with increasing the amplitudes of temperature dependence of viscosity, we identified the transition into the ＂stagnant-lid＂ （ST） regime, where the convection occurs only beneath a thick and stagnant-lid of cold fluid at the top surface. Detailed analysis showed a significant increase of the aspect ratio of convection cells in ST regime induced by the spatial variations in thermal conductivity and/or expansivity： the horizon- tal length scale of ST convection can be enlarged by up to 50% with 10 times increase of thermal conductivity with depth. We further developed an analytical model of ST convection which success- fully reproduced the mechanism of increasing horizontal length scale of ST regime convection cells for given spatial variations in physical properties. Our findings may highlight the essential roles of the spatial variation of thermal conductivity on the convection patterns in the mantle.
文摘The molar volume isotherms of trans-decahydronaphthalene （C10H18） between 293 and 446 K and at pressures from 10 to 200 MPa have been determined. A modified Tait equation of state is used to fit each experimental molar volume isotherm with a maximum average deviation of 0.029%. The thermal expansivity （cubic expansion coefficient） α and isothermal compressibility κ were determined by fitting the slopes of the isobaric curves and isotherms, respectively. The coefficients in the equation Vm=C1＋C2T＋C3T^2-C4p-C5pT have been fitted with an average deviation of 1.03%.
基金supported by National Natural Science Foundation of China(U2032118 and 42172048)Guizhou Provincial Science and Technology Projects(QKHPTRCYQK[2023]035 and QKHJC-ZK[2021]ZD042)+1 种基金Hundred Talents Program of the Chinese Academy of SciencesGuizhou Provincial 2020 and 2021 Science and Technology Subsidies(Nos.GZ2020SIG and GZ2021SIG)。
文摘The unit-cell parameters and volumes of geikielite(MgTiO_(3))and ilmenite(FeTiO_(3))were investigated at high temperatures up to 700 K and ambient pressure,using in-situ angle-dispersive synchrotron X-ray diffraction.No phase transition was detected over the experimental temperature range.Using(Berman in J Petrol29:445-522,1988.10.1093/petrology/29.2.445)equations to fit the temperature-volume data,the volumetric thermal expansion coefficients at ambient conditions(α_(V0))of MgTiO_(3) and FeTiO_(3) were obtained as follows:2.55(6)×10^(-5)K^(-1)and 2.82(10)×10^(-5)K^(-1),respectively.We infer that the larger effective ionic radius of Fe^(2+)(Ⅵ)(0.78 A)than that of Mg^(2+)(Ⅵ)(0.72?)renders FeTiO_(3)has a larger volumetric thermal expansivity than MgTiO_(3).Simultaneously,the refined axial thermal expansion coefficients under ambient conditions areα_(a0)=0.74(3)×10^(-5)K^(-1)andα_(c0)=1.08(5)×10^(-5)K^(-1)for the aaxis and c-axis of MgTiO_(3),respectively,andα_(a0)=0.95(5)×10^(-5)K^(-1)andα_(c0)=0.92(12)×10^(-5)K^(-1)for the aaxis and c-axis of FeTiO_(3),respectively.The axial thermal expansivity of MgTiO_(3) is anisotropic,but that of FeTiO_(3) is nearly isotropic.We infer that the main reason for the different axial thermal expansivity between MgTiO_(3) and FeTiO_(3) is that the thermal expansion mode of the Mg-O bond in MgTiO_(3) is different from that of the Fe-O bonds in FeTiO_(3).
基金National Key R&D Program of China(2022YFB2602900)R&D Fund Project of China Academy of Railway Sciences Corporation Limited(2021YJ084)+2 种基金Project of Science and Technology R&D Program of China Railway(2016G002-K)R&D Fund Project of China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.(2021)R&D Fund Project of China Railway Shanghai Group(2021141).
文摘Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.
基金supported by the National Natural Science Foundation of China(Grant Nos.12103059 and 12033007)the National Major Science and Technology Infrastructure Project of China(Grant No.2017-000052-73-01-002401)+3 种基金Xi’an Science and Technology Bureau(Grant No.E019XK1S04)Sanqin Talents’Special Support Program(Grant No.09R0557A00)the Youth Innovation Promotion Association of the Chinese Academy of Science(Grant No.1188000XGJ)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0300900)。
文摘High-finesse optical reference cavities are essential tools for fundamental research.In response to China’s historical reliance on importing high-finesse optical reference cavities,we successfully developed a cavity using ultralow expansion glass(ULE)materials and processed it entirely in China.Using the method of measuring the cavity linewidth,a finesse of approximately 480000 was obtained in our experiments.We adopted a relatively simple and effective approach to test the optical reference cavity,which involved measuring the resonant points using an ultrastable laser.Remarkably,an expansion coefficient of the Chinese ULE optical reference cavity reached up to the order of 10^(-9)/K within the temperature range of 27℃to 40℃,with the zero expansion point occurring at approximately 34oC.These findings demonstrate China’s independent capability to develop high-finesse optical reference cavities,which is a significant advancement in precision optics.
基金supported by the National Natural Science Foundation of China(52476200,52106244)the Guangdong Basic and Applied Basic Research Foundation(2024A1515030124)+1 种基金the Science and Technology Project of China Southern Power Grid under Grant GDKJXM20230246(030100KC23020017)the Fundamental Research Funds for the Central Universities。
文摘Due to batteries inconsistencies and potential faults in battery management systems,slight overcharging remains a common yet insufficiently understood safety risk,lacking effective warning methods.To illuminate the degradation behavior and failure mechanism of various overcharged states(100%SOC,105%SOC,110%SOC,and 115%SOC),multiple advanced in-situ characterization techniques(accelerating rate calorimeter,electrochemical impedance spectroscopy,ultrasonic scanning,and expansion instrument)were utilized.Additionally,re-overcharge-induced thermal runaway(TR)tests were conducted,with a specific emphasis on the evolution of the expansion force signal.Results indicated significant degradation at 110%SOC including conductivity loss,loss of lithium inventory,and loss of active material accompanied by internal gas generation.These failure behaviors slow down the expansion force rate during reovercharging,reducing the efficacy of active warnings that depend on rate thresholds of expansion force.Specifically,the warning time for 115%SOC battery is only 144 s,which is 740 s shorter than that for fresh battery,and the time to TR is advanced by 9 min.Moreover,the initial self-heating temperature(T1)is reduced by 62.4℃compared to that of fresh battery,reaching only 70.8℃.To address the low safety of overcharged batteries,a passive overcharge warning method utilizing relaxation expansion force was proposed,based on the continued gas generation after stopping charging,leading to a sustained increase in force.Compared to active methods that rely on thresholds of expansion force rate,the passive method can issue warnings 115 s earlier.By combining the passive and active warning methods,guaranteed effective overcharge warning can be issued 863-884 s before TR.This study introduces a novel perspective for enhancing the safety of batteries.
基金Supported by Projects from Chongqing Municipal Science and Technology Commission(CSTB2022NSCQ-MSX0445)。
文摘For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial quotients.In this paper,we establish the Hausdorff dimension of the exceptional set where the growth rate is a general function.
基金supported by the Fundamental Research Funds for the Central Universities(WK2090000055)Anhui Provincial Natural Science Foundation of China(2308085QG231).
文摘As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.
基金Supported by the National Natural Science Foundation of China(12001249)the Natural Science Foundation of Jiangxi Province(20232BAB211004)the Educational Commission Science Programm of Jiangxi Province(GJJ2200523)。
文摘In this paper,we establish common fixed point theorems for expansive map?pings on b-metric-like space and coincidence point for f-weakly isotone increasing mappings in partially ordered b-metric-like space.The main results generalize and extend several well-known comparable results from the existing literature.Moreover,some examples are provided to illustrate the main results.
基金National Natural Science Foundation of China(Grant No.42271214)National Key R&D Program of China(Grant No.2022YFC3800700)+1 种基金Key Research Program of Gansu Province(Grant No.23ZDKA0004)Natural Science Foundation of Gansu Province(Grant No.21JR7RA281).
文摘The expansion of construction land on slopes in mountainous cities like Lanzhou has addressed the shortage of flat land but compromised slope stability,leading to uneven land subsidence and risks to infrastructure.This study assessed the land subsidence before and after urban expansion in five areas of Lanzhou by using slope spectrum construction method and gradient expansion intensity measurement that integrated with SBAS-InSAR technology.The results show that construction land on slopes over 20°increased significantly,accounting for 16%of new construction land.The average slope spectrum index was 4.02,with the upper slope limit rising by 8.2°.The land subsidence rate threshold increased by 10 mm/a,and the proportion of pixels experiencing subsidence greater than 5 mm/year rose from 3.63%to 5.24%.Increased construction intensity on slopes caused higher and faster subsidence,which diminished with greater distance from the expansion areas.Areas with slopes between 10°and 25°saw the greatest acceleration in subsidence.Geological composition,building density,groundwater exploitation,and cut-and-fill thickness collectively influence land subsidence rates.This study provides a scientific basis for mitigating geological disaster risks and promoting safe urban development in mountainous cities.
基金supported by the Nanxun Scholars Program for Young Scholars of ZJWEU(No.RC2023021315)the start-up funding for Scientific Research for High-level Talents(No.88106324004)the National Natural Science Foundation of China(No.62304070).
文摘Silicon-based materials are considered as the next generation anode to replace graphite due to their low cost and ultra-high theoretical capacity.However,significant volume expansion and contraction occur during charging and discharging processes,leading to the instability of electrode structure and susceptibility to peeling and damage,limiting its application.Constructing controllable molecular artificial solid electrolyte interphase(CMASEI)is an effective approach to address the commercialization of silicon-based anode materials[1].Improving the performance of silicon-based anodes through CMASEI is a multifaceted outcome.
文摘For the people of Masaka,Kabuga and Muyumbu in Rwanda,the daily commute often takes longer than it should.A stretch of just 10 km along the Prince House-Giporoso-Masaka road can take half an hour during peak hours.The narrow two-lane artery,clogged with long-haul trucks from the Rwanda-Tanzania border and commuter traffic,has long tested the patience of drivers and pedestrians alike.In May,a long-awaited announcement finally arrived.Rwanda’s Ministry of Infrastructure confirmed plans to expand the road from two lanes to four,adding a 1.2-km flyover at Giporoso-Remera and an underpass to keep tra"c flowing smoothly.The$60.5 million(Rwf86 billion)project will be fully funded by China,a testament to the deepening friendship and cooperation between the two nations.For many residents,it signals the end of years of lost time and daily frustration.
基金National Key Research and Development Program of China,Grant/Award Number:2021YFA0805905,2023YFC3404305 and 2024YFA1107900the Strategic Priority Research Program of the Chinese Academy of Sciences,Grant/Award Number:XDB1150000+1 种基金the CAS Project for Young Scientists in Basic Research,Grant/Award Number:YSBR-012Bingtuan Science and Technology Project,Grant/Award Number:NYHXGG2023AA01。
文摘The clinical application of hepatocyte transplantation has been significantly hindered by the scarcity of primary hepatocytes and the functional immaturity of in vitro-pro-duced hepatocytes.By performing serial allogeneic hepatocyte transplantation in CRISPR/Cas9-mediated Fah-knockout pigs,we successfully achieved large-scale ex-pansion of hepatocytes while maintaining their authentic biological characteristics.Particularly,the established model enables sustained in vivo liver reconstruction,concurrently ameliorating hepatic fibrosis and demonstrating functional microenvi-ronmental remodeling.Moreover,through comprehensive single-cell transcriptomic profiling of 52418 hepatocytes across transplant generations(F0-F2),we discovered that the cellular composition of these transplanted hepatocytes is similar to that of wild-type hepatocytes.The regenerated liver exhibits all six major hepatic cell types identical to the wild-type counterparts,with the characteristic lobular zonation pat-terns well preserved.Our research provides valuable insights into the large-scale expansion of physiologically functional hepatocytes in vivo without compromising their biological properties.This finding holds great promise for advancing the clinical application of human hepatocyte transplantation,potentially offering more effective treatment options for patients with liver diseases.
基金financially supported by the Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)the National Natural Science Foundation of China(52374423)+1 种基金the Major Science and Technology Programs of Yunnan Province(202302AB080016)the Hunan Provincial Natural Science Youth Fund(2024JJ6726)。
文摘The capacitive deionization(CDI)performance of silver(Ag)electrodes is limited by electrochemical failure induced by volumetric expansion.While carbon encapsulation and Ag size control mitigate stress concentration and pulverization,achieving precise size control,suppression of aggregation,and uniform dispersion of Ag nanoparticles remains challenging.Herein,the metal-organic frameworks(MOF)-assisted pyrolysis-galvanic replacement method was employed to construct ultrafine Ag particles uniformly anchored within a three-dimensional(3D)-ordered porous carbon skeleton composite(3D Ag@NC).By utilizing the potential difference between the elements,spontaneous replacement reactions occur,effectively preventing particle agglomeration usually caused by high-temperature reduction.The in situ constructed 3D porous carbon skeleton not only promotes electron transfer and electrolyte penetration but also mitigates the volume expansion of Ag particles during electrochemical cycling.Consequently,3D Ag@NC demonstrates outstanding dechlorination performance(105.29 mg g^(-1)),high charge efficiency(0.95),and exceptional cycling stability(84.12% after 100 cycles).This galvanic replacement strategy offers valuable insights into the fabrication of other small-sized,highly dispersed metal electrode materials.
基金supported by the National Natural Science Foundation of China(grant nos.82102343 and 82372536)the Shanghai Municipal Health Commission Health Industry Clinical Research Special Program(grant no.20244Y0031)the Shanghai“Rising Stars of Medical Talents”Youth Development Program(Youth Medical Talents-Specialist Program).
文摘Tissue expansion is a widely utilized technique in plastic and reconstructive surgery;however,the biological mechanisms underlying the skin response remain poorly understood.We propose that tissue fluidity,the transition of tissue from a solid-like state to a fluid-like state,plays a pivotal role in enabling the reorganization of the epidermal structure and cellular spatial order,which is essential for effective tissue expansion.Drawing parallels between fluidity in materials science and biological systems,we suggest that the fluid-like behavior in the skin may be critical for mechanical adaptability.Understanding the influence of tissue fluidity may open pathways for modulating this process,potentially enhancing tissue expansion efficiency,reducing procedural duration,and improving clinical outcomes.This perspective highlights the importance of investigating the biological dynamics of tissue fluidity and exploring the potential for targeted manipulation of fluidity-related pathways to optimize tissue expansion.Such advancements could profoundly affect regenerative and reconstructive surgical practices.
基金financially supported by the CITIC niobium steel development award Fund(M1656-2021)Central Iron and Steel Research Institute for its independent research and development fund(No.21G62460ZD).
文摘Increasing the hole expansion ratio is significant for developing high formability parts.Hole expansion tests were carried out on low carbon hot-rolled steel containing 0.11%Ti,0.072%Ti–0.03%Nb and 0.097%Ti–0.059%Nb,respectively.The effects of microstructure,texture,crack propagation behavior and second phase precipitation behavior on hole expansion ratio were investigated.The precipitation behavior of TiC and(Ti,Nb)C in austenite and ferrite in three groups of steel samples was calculated theoretically.The results showed that the hole expansion ratios of 0.11Ti,0.072Ti–0.03Nb and 0.097Ti–0.059Nb test steels were 51.73%,51.17%and 66.24%following simulated coiling at 600℃,respectively.The microstructure was mainly polygonal ferrite with a small amount of pearlite.The grain refinement of 0.097Ti–0.059Nb test steel and the low texture ratio of{110}//ND improved the hole expansion ratio.The low overall hole expansion ratio was due to the microstructure inhomogeneity.The microstructure uniformity was improved by the quenching and tempering treatment,and the hole expansion ratio of the three test steels was greatly increased.The fastest precipitation temperatures in the austenitic region of 0.11Ti,0.072Ti–0.03Nb and 0.097Ti–0.059Nb test steels were 880,860 and 830℃,while those in the ferrite region were 680,675 and 675℃,respectively.The addition of Nb element increased the volume free energy,so that the critical core size of the nucleation on the dislocation line increased,resulting in the decrease in the fastest precipitation temperature.
基金financial support from the National Natural Science Foundation of China(Nos.22261057 and 21901265)Guizhou Provincial Natural Science Foundation(No.QKHJC-2020-1Z072)+3 种基金the Science and Technology Department of Guizhou Province(Nos.QKHPTRC-CXTD[2022]012 and QKHPTRCGCC[2023]003)Zunyi Medical University(No.18ZY-002)Science and Technology Department of Zunyi(Nos.ZSKH-2018-3,ZSKHHZZ[2020]70,ZSKRPT-2020-5 and ZSKRPT-2021-5)Fifth Batch of Talent Base in Guizhou Province(No.S-030-1).
文摘Catalytic syntheses of silaoxycarbocyclics from an interrupted Catellani reaction of 3-iodochromones with bridged olefins and octamethyl-1,4-dioxacyclohexasilane is described.This protocol involves the oxidative addition of chromonyl-norbornyl-palladacycle generated through successive oxidative addition of Pd(0)to 3-iodochromones,migratory insertion of NBE and intramolecular ortho-C(sp^(2))-H activation to the tetrasilane,thus motivating a(4+6)annulation and ring expansion.The synthetic practicality of current strategy is further proved by the late-stage modification of pharmaceuticals and natural products,gram-scale experiments,as well as the transformations of functional groups of silaoxycarbocyclics.
文摘While the Trump administration’s new measures mean negative repercussions for the entire world,Chinese AI company DeekSeek’s innovation is a gift for the progress of all.THE United States ending its World Health Organization(WHO)membership,rejecting the Paris Climate Agreement,expressing expansionist ambitions over Greenland,Canada,Mexico and Panama,and declaring trade wars in the early days of the new Trump administration contrasts sharply with another disruptive development in another part of the world-the announcement by Chinese artificial intelligence(AI)company DeepSeek that its revolutionary AI model will be open to all.Two antipode disruptions indeed.
