The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ...The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ simulations with varied protocols to evaluate the effectiveness of different descriptors in predicting mechanical properties across both low-and high-pressure regimes.Our findings demonstrate that conventional structural and configurational descriptors fail to correlate with the mechanical response following pressure release,whereas the activation energy descriptor exhibits robust linearity with shear modulus after correcting for pressure effects.Notably,the soft mode parameter emerges as an ideal and computationally efficient alternative for capturing this mechanical behavior.These findings provide critical insights into the influence of pressure on glassy properties,integrating the distinct features of compressed glasses into a unified theoretical framework.展开更多
On approaching the glass transition,the structural relaxation of glass-forming liquids slows down drastically,along with a significant growth of dynamic heterogeneity.Recent studies have achieved substantial advanceme...On approaching the glass transition,the structural relaxation of glass-forming liquids slows down drastically,along with a significant growth of dynamic heterogeneity.Recent studies have achieved substantial advancements in elucidating the quantitative correlations between structural relaxation and dynamic heterogeneity.Here,we present the discovery of a novel dynamic crossover with possibly universal dynamic signatures by investigating the relationship between structural relaxation and dynamic heterogeneity.Specifically,the structural relaxation time at the dynamic crossoverτ_(c)is equal to the time scale for the maximum non-Gaussian parameter,which could serve as a quantitative characterization of dynamic heterogeneity.The degree of dynamic heterogeneity at the crossover is approximately equivalent across all investigated glass-forming liquids,leading to a scaling collapse between structural relaxation and dynamic heterogeneity.Moreover,the mean squared displacement at the structural relaxation time is nearly constant across different temperatures as long as the structural relaxation time does not exceedτ_(c).We further observe that the temperature at the dynamic crossover is lower than the onset temperature of slow dynamics.Our findings thus suggest the existence of a novel dynamic crossover with possibly universal dynamic signatures in glass-forming liquids,which merits in-depth investigations.展开更多
The glass-forming ability(GFA)of metallic glasses is a key scientific challenge in their development and application,with compositional dependence playing a crucial role.Experimental studies have demonstrated that the...The glass-forming ability(GFA)of metallic glasses is a key scientific challenge in their development and application,with compositional dependence playing a crucial role.Experimental studies have demonstrated that the addition of specific minor elements can greatly enhance the GFA of parent alloys,yet the underlying mechanism remains unclear.In this study,we use the ZrCuAl system as a model to explore how the addition of minor Al influences the crystallization rate by modulating the properties of the crystal-liquid interface,thereby affecting the GFA.The results reveal that the minor addition of Al significantly reduces the crystal growth rate,a phenomenon not governed by particle density fluctuations at the interface.The impact of minor element additions extends beyond a modest increase in crystal-unfavorable motifs in the bulk supercooled liquid.More importantly,it leads to a significant enrichment of these motifs at the crystal-supercooled liquid interface,forming a dense topological network of crystal-unfavorable structures that effectively prevent the growth of the crystalline interface and enhance GFA.Our results provide valuable insights for the design and development of high-performance metallic glasses.展开更多
To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications,the wood was impregnated and modified.An organic phenolic prepolymer and inorganic s...To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications,the wood was impregnated and modified.An organic phenolic prepolymer and inorganic sodium silicate was used as contrasting impregnation modifiers and wood samples were impregnated by a bionic“respiration”method with alternating positive and negative pressure.The weight percentage gain,density increase ratio,mechanical properties(bending and compressive strength and hardness),and water absorption rate of inorganic and organic-impregnated modified poplar wood(IIMPW and OIMPW,respectively)were compared and these properties in IIMPW were found to be higher than those of OIMPW with the exception of the water absorption rate which was lower than the OIMPW.This was attributed to the superior absorption of sodium silicate that also improved the impregnation,reinforcement,and dimensional stability in the IIMPW.The chemical structure,crystalline structure,internal morphology,flame retardancy,smoke suppression,and thermal stability of IIMPW and OIMPW were characterized by FT-IR,XRD,SEM,CONE,and TGA.FT-IR and XRD results showed that,although IIMPW cellulose crystallinity reduced the most,more chemical bonds were come into being in IIMPW,which explained the better physical and mechanical properties of IIMPW.Compared with OIMPW,IIMPW had better flame retardant and smoke suppression performance.展开更多
In recent years,electrically conductive hydrogel-based nerve guidance conduits(NGCs)have yielded promising results for treating peripheral nerve injuries(PNIs).However,developed ones are generally pre-manufactured and...In recent years,electrically conductive hydrogel-based nerve guidance conduits(NGCs)have yielded promising results for treating peripheral nerve injuries(PNIs).However,developed ones are generally pre-manufactured and exhibit a limited ability to achieve good contact with nerve tissue with irregu-lar surfaces.Herein,we developed a plasticine-like electrically conductive hydrogel consisting of gelatin,conducting polypyrrole,and tannic acid(named GPT)and assessed its ability to promote peripheral nerve regeneration.The shape-persistent GPT hydrogel exhibited good self-healing properties and could easily be molded to form a conduit that could match any injured nerve tissue.Their electrical properties could be tuned by changing the PPy concentration.In vitro,the improved conductivity of the hydrogel pro-moted dorsal root ganglion(DRG)axonal extension.More importantly,we found that the GPT hydrogel enhanced axonal regeneration and remyelination in vivo,preventing denervation atrophy and enhancing functional recovery in a mice model of sciatic nerve injury.These results suggest that our plasticine-like NGC has huge prospects for clinical application in the repair of PNI.展开更多
Sodium silicate modification can improve the overall performance of wood.The modification process has a great influence on the properties of modified wood.In this study,a new method was introduced to analyze the wood ...Sodium silicate modification can improve the overall performance of wood.The modification process has a great influence on the properties of modified wood.In this study,a new method was introduced to analyze the wood modification process,and the properties of modified wood were studied.Poplar wood was modified with sodium silicate by vacuum-pressure impregnation.After screening using single-factor experiments,an orthogonal experiment was carried out with solution concentration,impregnation time,impregnation pressure,and the cycle times as experimental factors.The modified poplar with the best properties was selected by fuzzy mathematics and characterized by SEM,FT-IR,XRD and TG.The results showed that some lignin and hemicellulose were removed from the wood due to the alkaline action of sodium silicate,and the orderly crystal area of poplar became disorderly,resulting in the reduction of crystallinity of the modified poplar wood.FT-IR analysis showed that sodium silicate was hydrolyzed to form polysilicic acid in wood,and structural analysis revealed the formation of Si-O-Si and Si-O-C,indicating that sodium silicate reacted with fibers on the wood cell wall.TG-DTG curves showed that the final residual mass of modified poplar wood increased from 25%to 67%,and the temperature of the maximum loss rate decreased from 343℃ to 276℃.The heat release and smoke release of modified poplar wood decreased obviously.This kind of material with high strength and fire resistance can be used in the outdoor building and indoor furniture.展开更多
The lack of the long-range order in the atomic structure challenges the identification of the structural defects,akin to dislocations in crystals,which are responsible for predicting plastic events and mechanical fail...The lack of the long-range order in the atomic structure challenges the identification of the structural defects,akin to dislocations in crystals,which are responsible for predicting plastic events and mechanical failure in metallic glasses(MGs).Although vast structural indicators have been proposed to identify the structural defects,quantitatively gauging the correlations between these proposed indicators based on the undeformed configuration and the plasticity of MGs upon external loads is still lacking.Here,we systematically analyze the ability of these indicators to predict plastic events in a representative MG model using machine learning method.Moreover,we evaluate the influences of coarse graining method and medium-range order on the predictive power.We demonstrate that indicators relevant to the low-frequency vibrational modes reveal the intrinsic structural characteristics of plastic rearrangements.Our work makes an important step towards quantitative assessments of given indicators,and thereby an effective identification of the structural defects in MGs.展开更多
We report the dynamic crossover behavior in metallic glass nanoparticles(MGNs)with the size reduction based on the extensive molecular dynamics(MD)simulations combined with the activation-relaxation technique(ART).The...We report the dynamic crossover behavior in metallic glass nanoparticles(MGNs)with the size reduction based on the extensive molecular dynamics(MD)simulations combined with the activation-relaxation technique(ART).The fragile-to-strong transition of dynamics can be achieved by just modulating the characteristic size of MGNs.It can be attributed to the abnormal fast surface dynamics enhanced by the surface curvature.By determining the potential energy surface,we reveal the hierarchy-to-flat transition of potential energy landscape(PEL)in MGNs,and demonstrate the intrinsic flat potential landscape feature of the MGN with size smaller than a critical size.Our results provide an important piece of the puzzle about the size-modulated potential energy landscape and shed some lights on the unique properties of MGs in nanoscale.展开更多
This paper provides a comprehensive overview of the latest stable release of the graphics processing units molecular dynamics(GPUMD)package,GPUMD 4.0.We begin with a brief review of its development history,starting fr...This paper provides a comprehensive overview of the latest stable release of the graphics processing units molecular dynamics(GPUMD)package,GPUMD 4.0.We begin with a brief review of its development history,starting from the initial version.We then discuss the theoretical foundations for the development of the GPUMD package,including the formulations of the interatomic force,virial and heat current for many-body potentials,the development of the highly efficient and flexible neuroevolution potential(NEP)method,the supported integrators and related operations,the various physical properties that can be calculated on the fly,and the GPUMD ecosystem.After presenting these functionalities,we review a range of applications enabled by GPUMD,particularly in combination with the NEP approach.Finally,we outline possible future development directions for GPUMD.展开更多
Carbon-sulfur composites have draw n in creasing interest in various fields including electrocatalysis because of their unique structures.However,carb on-sulfur composite with tiny sulfur nano crystals has still recei...Carbon-sulfur composites have draw n in creasing interest in various fields including electrocatalysis because of their unique structures.However,carb on-sulfur composite with tiny sulfur nano crystals has still received little attention.Herein,hollow porous carb on sphere-sulfur composite(HPCS-S)which possesses excellent electrochemical performance towards H2O2 has been prepared for the first time via a simple silica template method.The 2-5 nm sulfur nan ocrystals being restricted in the cha nnel of the hollow porous carb on spheres are un der a strong compressive stress,which was further con firmed by high-resoluti on tran smissi on electr on microscopy(HRTEM)and GPA.The HPCS-S nano crystals show better con ductivity tha n amorphous sulfur clusters because of the reducti on of the steric hindrance which efficie ntly promotes the electron transportation.Consequently,the higher activity and selectivity towards the 2e^oxygen reduction reaction(ORR)to H2O2 in alkaline solution was obtained.The H2O2 selectivity rises from 20%to over 70%after the sulfur addition and the H2O2 production rate achieves 183.99 mmol-gcataiyst-1 with the Faradaic efficiency of 70%.Furthermore,performance enhancement mechanism was also investigated using the den sity functional theory(DFT)calculatio ns.After the in troduci ng of sulfur nano crystals,the appeara nee of S-S bond greatly decreases the overpotential compared with S-doping,which results in significant enhancement of the electrocatalytic property.Consequently,the HPCS-S can be an efficient H2O2 production electrocatalyst in alkaline solution.展开更多
Growth plate cartilage has limited self-repair ability,leading to poor bone bridge formation post-injury and ultimately limb growth defects in children.The current corrective surgeries are highly invasive,and outcomes...Growth plate cartilage has limited self-repair ability,leading to poor bone bridge formation post-injury and ultimately limb growth defects in children.The current corrective surgeries are highly invasive,and outcomes can be unpredictable.Following growth plate injury,the direct loss of extracellular matrix(ECM)coupled with further ECM depletion due to the inhibitory effects of inflammation on the cartilage matrix protein greatly hinder chondrocyte regeneration.We designed an exosome(Exo)derived from bone marrow mesenchymal stem cells(BMSCs)loaded ECM-mimic hydrogel to promote cartilage repair by directly supplementing ECM and anti-inflammatory properties.Aldehyde-functionalized chondroitin sulfate(OCS)was introduced into gelatin methacryloyl(GM)to form GMOCS hydrogel.Our results uncovered that GMOCS hydrogel could significantly promote the synthesis of ECM due to the doping of OCS.In addition,the GMOCS-Exos hydrogel could further promote the anabolism of chondrocytes by inhibiting inflammation and ultimately promote growth plate injury repair through ECM remodeling.展开更多
The host immune response effecting on biomaterials is critical to determine implant fates and bone regeneration property.Bone marrow stem cells(BMSCs)derived exosomes(Exos)contain multiple biosignal molecules and have...The host immune response effecting on biomaterials is critical to determine implant fates and bone regeneration property.Bone marrow stem cells(BMSCs)derived exosomes(Exos)contain multiple biosignal molecules and have been demonstrated to exhibit immunomodulatory functions.Herein,we develop a BMSC-derived Exos-functionalized implant to accelerate bone integration by immunoregulation.BMSC-derived Exos were reversibly incorporated on tannic acid(TA)modified sulfonated polyetheretherketone(SPEEK)via the strong interaction of TA with biomacromolecules.The slowly released Exos from SPEEK can be phagocytosed by co-cultured cells,which could efficiently improve the biocompatibilities of SPEEK.In vitro results showed the Exos loaded SPEEK promoted macrophage M2 polarization via the NF-κB pathway to enhance BMSCs osteogenic differentiation.Further in vivo rat air-pouch model and rat femoral drilling model assessment of Exos loaded SPEEK revealed efficient macrophage M2 polarization,desirable new bone formation,and satisfactory osseointegration.Thus,BMSC-derived Exos-functionalized implant exerted osteoimmunomodulation effect to promote osteogenesis.展开更多
Injectable biomaterial-based treatment is a promising strategy to enhance tissue repair after traumatic spinal cord injury(SCI)by bridging cavity spaces.However,there are limited reports of injectable,electroconductiv...Injectable biomaterial-based treatment is a promising strategy to enhance tissue repair after traumatic spinal cord injury(SCI)by bridging cavity spaces.However,there are limited reports of injectable,electroconductive hydrogels with self-healing properties being employed for the treatment of traumatic SCI.Hence,a natural extracellular matrix(ECM)biopolymer(chondroitin sulphate and gelatin)-based hydrogel containing polypyrrole,which imparted electroconductive properties,is developed for traumatic SCI repair.The resulting hydrogels showed mechanical(~928 Pa)and conductive properties(4.49 mS/cm)similar to natural spinal cord tissues.Moreover,the hydrogels exhibited shear-thinning and self-healing abilities,which allows it to be effectively injected into the injury site and to fill the lesion cavity to accelerate the tissue repair of traumatic SCI.In vitro,electroconductive ECM hydrogels promoted neuronal differentiation,enhanced axon outgrowth,and inhibited astrocyte differentiation.The electroconductive ECM hydrogel activated endogenous neural stem cell neurogenesis in vivo(n=6),and induced myelinated axon regeneration into the lesion site via activation of the PI3K/AKT and MEK/ERK pathways,thereby achieving significant locomotor function restoration in rats with spinal cord injury(p<0.001,compared to SCI group).Overall,the injectable self-healing electroconductive ECM-based hydrogels developed in this study are ideal biomaterials for treatment of traumatic SCI.展开更多
In crystalline solids,plastic deformation is determined by the motion of structural defects,particularly dislocations.As for glassy liquids and disordered solids,it has long been assumed that localized structural rear...In crystalline solids,plastic deformation is determined by the motion of structural defects,particularly dislocations.As for glassy liquids and disordered solids,it has long been assumed that localized structural rearrangements induced by mechanical load or thermal stimulus also occur at localized defects[1-3].展开更多
Computational simulation provides an effective way of understanding the disordered structure and structureproperty relationships for metallic glass systems.Here,we systematically investigated the finite-size effects o...Computational simulation provides an effective way of understanding the disordered structure and structureproperty relationships for metallic glass systems.Here,we systematically investigated the finite-size effects of the static structure and dynamical behaviors in a three-dimensional Cu50Zr50 model metallic glass via classical molecular dynamics(MD)simulations.It was found that the local structure is insensitive to the system size while the dynamical properties present evident finite-size effects.The decoupling between local structure and relaxation dynamics in the investigated supercooling emerges when the system contains less than~2000 atoms.However,the collapse can be observed between the structural relaxation time and the dynamical heterogeneity for different sized systems across the whole range of our investigation.Our results support the intrinsic link between the structural relaxation time and dynamic heterogeneity and reveal the critical simulated system size for representing the structural origins of dynamics in bulk metallic glass with ignorable surface effects.展开更多
Conductive scaffolds have been shown to exert a therapeutic effect on patients suffering from peripheral nerve injuries(PNIs).However,conventional conductive conduits are made of rigid structures and have limited appl...Conductive scaffolds have been shown to exert a therapeutic effect on patients suffering from peripheral nerve injuries(PNIs).However,conventional conductive conduits are made of rigid structures and have limited applications for impaired diabetic patients due to their mechanical mismatch with neural tissues and poor plasticity.We propose the development of biocompatible electroconductive hydrogels(ECHs)that are identical to a surgical dressing in this study.Based on excellent adhesive and self-healing properties,the thin film-like dressing can be easily attached to the injured nerve fibers,automatically warps a tubular structure without requiring any invasive techniques.The ECH offers an intimate and stable electrical bridge coupling with the electrogenic nerve tissues.The in vitro experiments indicated that the ECH promoted the migration and adhesion of the Schwann cells.Furthermore,the ECH facilitated axonal regeneration and remyelination in vitro and in vivo through the MEK/ERK pathway,thus preventing muscle denervation atrophy while retaining functional recovery.The results of this study are likely to facilitate the development of non-invasive treatment techniques for PNIs in diabetic patients utilizing electroconductive hydrogels.展开更多
The fast dynamic properties of the surface of metallic glasses(MGs) play a critical role in determining their potential applications. However, due to the significant difference in thermal history between atomic simula...The fast dynamic properties of the surface of metallic glasses(MGs) play a critical role in determining their potential applications. However, due to the significant difference in thermal history between atomic simulation models and laboratory-made samples, the atomic-scale behaviors of the fast surface dynamics of MGs in experiments remain uncertain. Herein, we prepared model MG films with notable variations in thermal stability using a recently developed efficient annealing protocol, and investigated their atomic-scale dynamics systematically. We found that the dynamics of surface atoms remain invariant, whereas the difference in dynamical heterogeneity between surface and interior regions increases with the improvement of thermal stability. This can be associated with the more pronounced correlation between atomic activation energy spectra and depth from the surface in samples with higher thermal stability. In addition, dynamic anisotropy appears for surface atoms, and their transverse dynamics are faster than normal components, which can also be interpreted by activation energy spectra. Our results reveal the presence of strong liquid-like atomic dynamics confined to the surface of laboratory-made MGs, illuminating the underlying mechanisms for surface engineering design, such as cold joining by ultrasonic vibrations and superlattice growth.展开更多
Single oxygen diffusion event,the most favorable rate-limiting process of epitaxial Cu_(2)O oxide-island layerby-layer growth kinetics,may lead to oxygen defects due to thermomechanical coupling.However,the formation ...Single oxygen diffusion event,the most favorable rate-limiting process of epitaxial Cu_(2)O oxide-island layerby-layer growth kinetics,may lead to oxygen defects due to thermomechanical coupling.However,the formation rules of oxygen defects remain unclear,preventing the realization of controllable oxygen defects on oxide-island surfaces.Here,we utilize the first-principles method to investigate the formation rules of intrinsic oxygen defects in the surface layers of prototypical metal-oxide(Cu_(2)O)surfaces under thermomechanical coupling effects.We establish the thermodynamic phase diagram for oxygen-defect-modulated Cu_(2)O surfaces,enabling the prediction of the growth of oxide islands during Cu oxidation,which aligns closely with in-situ environmental transmission electron microscopy(ETEM)experiment observations.By exploring the strain-modulated phase diagrams,we propose a potential strategy for controlling the type and concentration of oxygen defects on oxide-island surfaces.Our findings provide an effective approach to theoretically understanding the oxidation process of metal surfaces,thus enabling the computational design of high-performance corrosion-resistant surfaces.展开更多
As a common but critical dynamic crossover in glass-forming liquids(GFLs),the discovery of fragile-to-strong(F-S)transition promises a novel route for understanding supercooled liquid and glass transition.The present ...As a common but critical dynamic crossover in glass-forming liquids(GFLs),the discovery of fragile-to-strong(F-S)transition promises a novel route for understanding supercooled liquid and glass transition.The present work,for the first time,successfully realizes the quantitative prediction of the F-S transition in nine metallic glass-forming liquids,by a counter-intuitive approach that focuses on local atomic activation events,rather than relaxation,upon cooling.The dynamic crossover originates from a disorder-to-order transition by self-regulating behavior of atomic position within a cage controlled by finite atomic activation events,due to the appearance of local cooperative motion of nearest neighborhood atoms.Moreover,the dominant role of entropy in this anomaly has been discovered,and the correspondence between the crossover of configuration entropy involved in activation events and the occurrence of F-S transition has been found.Our work implies that the feature of atomic energy fluctuations reflected by atomic activation events has a close linkage to complex dynamic behaviors of disordered systems.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.T2325004 and 52161160330)the National Natural Science Foundation of China (Grants No.12504233)+2 种基金Advanced MaterialsNational Science and Technology Major Project (Grant No.2024ZD0606900)the Talent Hub for “AI+New Materials” Basic Researchthe Key Research and Development Program of Ningbo (Grant No.2025Z088)。
文摘The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ simulations with varied protocols to evaluate the effectiveness of different descriptors in predicting mechanical properties across both low-and high-pressure regimes.Our findings demonstrate that conventional structural and configurational descriptors fail to correlate with the mechanical response following pressure release,whereas the activation energy descriptor exhibits robust linearity with shear modulus after correcting for pressure effects.Notably,the soft mode parameter emerges as an ideal and computationally efficient alternative for capturing this mechanical behavior.These findings provide critical insights into the influence of pressure on glassy properties,integrating the distinct features of compressed glasses into a unified theoretical framework.
基金support from the National Natural Science Foundation of China(Grant Nos.12374202 and 12004001)Anhui Projects(Grant Nos.2022AH020009,S020218016,and Z010118169),and Hefei City(Grant No.Z020132009)+3 种基金support from the National Natural Science Foundation of China(Grant Nos.T2325004 and 52161160330)Advanced Materials-National Science and Technology Major Project(Grant No.2024ZD0606900)the Talent Hub for“AI+New Materials”Basic ResearchHefei Advanced Computing Center,Beijing Super Cloud Computing Center,and the High-Performance Computing Platform of Anhui University for providing computing resources.
文摘On approaching the glass transition,the structural relaxation of glass-forming liquids slows down drastically,along with a significant growth of dynamic heterogeneity.Recent studies have achieved substantial advancements in elucidating the quantitative correlations between structural relaxation and dynamic heterogeneity.Here,we present the discovery of a novel dynamic crossover with possibly universal dynamic signatures by investigating the relationship between structural relaxation and dynamic heterogeneity.Specifically,the structural relaxation time at the dynamic crossoverτ_(c)is equal to the time scale for the maximum non-Gaussian parameter,which could serve as a quantitative characterization of dynamic heterogeneity.The degree of dynamic heterogeneity at the crossover is approximately equivalent across all investigated glass-forming liquids,leading to a scaling collapse between structural relaxation and dynamic heterogeneity.Moreover,the mean squared displacement at the structural relaxation time is nearly constant across different temperatures as long as the structural relaxation time does not exceedτ_(c).We further observe that the temperature at the dynamic crossover is lower than the onset temperature of slow dynamics.Our findings thus suggest the existence of a novel dynamic crossover with possibly universal dynamic signatures in glass-forming liquids,which merits in-depth investigations.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.T2325004 and 52161160330)the support from the Hong Kong Institute of Advanced Studies through the materials cluster project。
文摘The glass-forming ability(GFA)of metallic glasses is a key scientific challenge in their development and application,with compositional dependence playing a crucial role.Experimental studies have demonstrated that the addition of specific minor elements can greatly enhance the GFA of parent alloys,yet the underlying mechanism remains unclear.In this study,we use the ZrCuAl system as a model to explore how the addition of minor Al influences the crystallization rate by modulating the properties of the crystal-liquid interface,thereby affecting the GFA.The results reveal that the minor addition of Al significantly reduces the crystal growth rate,a phenomenon not governed by particle density fluctuations at the interface.The impact of minor element additions extends beyond a modest increase in crystal-unfavorable motifs in the bulk supercooled liquid.More importantly,it leads to a significant enrichment of these motifs at the crystal-supercooled liquid interface,forming a dense topological network of crystal-unfavorable structures that effectively prevent the growth of the crystalline interface and enhance GFA.Our results provide valuable insights for the design and development of high-performance metallic glasses.
基金the Scientific Research Project of Hunan Provincial Education Department,China(21B0238)Hunan Provincial Technical Innovation Platform and Talent Program in Science and Technology,China(2019RS2040)+1 种基金National Natural Science Foundation of China(32171708)The Science and Technology Innovation Program of Hunan Province(2021RC4062).
文摘To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications,the wood was impregnated and modified.An organic phenolic prepolymer and inorganic sodium silicate was used as contrasting impregnation modifiers and wood samples were impregnated by a bionic“respiration”method with alternating positive and negative pressure.The weight percentage gain,density increase ratio,mechanical properties(bending and compressive strength and hardness),and water absorption rate of inorganic and organic-impregnated modified poplar wood(IIMPW and OIMPW,respectively)were compared and these properties in IIMPW were found to be higher than those of OIMPW with the exception of the water absorption rate which was lower than the OIMPW.This was attributed to the superior absorption of sodium silicate that also improved the impregnation,reinforcement,and dimensional stability in the IIMPW.The chemical structure,crystalline structure,internal morphology,flame retardancy,smoke suppression,and thermal stability of IIMPW and OIMPW were characterized by FT-IR,XRD,SEM,CONE,and TGA.FT-IR and XRD results showed that,although IIMPW cellulose crystallinity reduced the most,more chemical bonds were come into being in IIMPW,which explained the better physical and mechanical properties of IIMPW.Compared with OIMPW,IIMPW had better flame retardant and smoke suppression performance.
基金financially supported by the National Natural Science Foundation of China(Nos.51932002 and 51903087)the Science and Technology Innovation Team Project of Foshan(No.2018IT100101)the Joint Fund of Ministry of Education for Equipment Preresearch(No.6141A02022632).
文摘In recent years,electrically conductive hydrogel-based nerve guidance conduits(NGCs)have yielded promising results for treating peripheral nerve injuries(PNIs).However,developed ones are generally pre-manufactured and exhibit a limited ability to achieve good contact with nerve tissue with irregu-lar surfaces.Herein,we developed a plasticine-like electrically conductive hydrogel consisting of gelatin,conducting polypyrrole,and tannic acid(named GPT)and assessed its ability to promote peripheral nerve regeneration.The shape-persistent GPT hydrogel exhibited good self-healing properties and could easily be molded to form a conduit that could match any injured nerve tissue.Their electrical properties could be tuned by changing the PPy concentration.In vitro,the improved conductivity of the hydrogel pro-moted dorsal root ganglion(DRG)axonal extension.More importantly,we found that the GPT hydrogel enhanced axonal regeneration and remyelination in vivo,preventing denervation atrophy and enhancing functional recovery in a mice model of sciatic nerve injury.These results suggest that our plasticine-like NGC has huge prospects for clinical application in the repair of PNI.
基金This work was financially supported by National Natural Science Foundation of China(32201485)Natural Science Foundation of Hunan Province,China(2022JJ40863)+1 种基金Scientific Research Project of Hunan Provincial Education Department,China(21B0238)The Science and Technology Innovation Program of Hunan Province(2021RC4062).
文摘Sodium silicate modification can improve the overall performance of wood.The modification process has a great influence on the properties of modified wood.In this study,a new method was introduced to analyze the wood modification process,and the properties of modified wood were studied.Poplar wood was modified with sodium silicate by vacuum-pressure impregnation.After screening using single-factor experiments,an orthogonal experiment was carried out with solution concentration,impregnation time,impregnation pressure,and the cycle times as experimental factors.The modified poplar with the best properties was selected by fuzzy mathematics and characterized by SEM,FT-IR,XRD and TG.The results showed that some lignin and hemicellulose were removed from the wood due to the alkaline action of sodium silicate,and the orderly crystal area of poplar became disorderly,resulting in the reduction of crystallinity of the modified poplar wood.FT-IR analysis showed that sodium silicate was hydrolyzed to form polysilicic acid in wood,and structural analysis revealed the formation of Si-O-Si and Si-O-C,indicating that sodium silicate reacted with fibers on the wood cell wall.TG-DTG curves showed that the final residual mass of modified poplar wood increased from 25%to 67%,and the temperature of the maximum loss rate decreased from 343℃ to 276℃.The heat release and smoke release of modified poplar wood decreased obviously.This kind of material with high strength and fire resistance can be used in the outdoor building and indoor furniture.
基金the Science Challenge Project(Grant No.TZ2018004)the NSAF Joint Program(Grant No.U1930402)+1 种基金the National Natural Science Foundation of China(Grant No.51801230)the National Key Research and Development Program of China(Grant No.2018YFA0703601).
文摘The lack of the long-range order in the atomic structure challenges the identification of the structural defects,akin to dislocations in crystals,which are responsible for predicting plastic events and mechanical failure in metallic glasses(MGs).Although vast structural indicators have been proposed to identify the structural defects,quantitatively gauging the correlations between these proposed indicators based on the undeformed configuration and the plasticity of MGs upon external loads is still lacking.Here,we systematically analyze the ability of these indicators to predict plastic events in a representative MG model using machine learning method.Moreover,we evaluate the influences of coarse graining method and medium-range order on the predictive power.We demonstrate that indicators relevant to the low-frequency vibrational modes reveal the intrinsic structural characteristics of plastic rearrangements.Our work makes an important step towards quantitative assessments of given indicators,and thereby an effective identification of the structural defects in MGs.
基金Supported by the Science Challenge Project(Grant No.TZ2018004)the National Natural Science Foundation of China(Grant No.U1930402)S.Z.and P.G.acknowledge the computational support from the Beijing Computational Science Research Center(CSRC).
文摘We report the dynamic crossover behavior in metallic glass nanoparticles(MGNs)with the size reduction based on the extensive molecular dynamics(MD)simulations combined with the activation-relaxation technique(ART).The fragile-to-strong transition of dynamics can be achieved by just modulating the characteristic size of MGNs.It can be attributed to the abnormal fast surface dynamics enhanced by the surface curvature.By determining the potential energy surface,we reveal the hierarchy-to-flat transition of potential energy landscape(PEL)in MGNs,and demonstrate the intrinsic flat potential landscape feature of the MGN with size smaller than a critical size.Our results provide an important piece of the puzzle about the size-modulated potential energy landscape and shed some lights on the unique properties of MGs in nanoscale.
基金supported by the National Science and Technology Advanced Materials Major Program of China(No.2024ZD0606900)W.Ouyang acknowledges the financial support from the National Natural Science Foundation of China(No.12472099)+10 种基金the Fundamental Research Funds for the Central Universities(No.2042025kf0050)S.Pan,Y.Wang,J.Shi,Z.Liang,J.Wang,and J.Sun acknowledge the financial support from the National Natural Science Foundation of China(Nos.12125404,T2495231,and 123B2049)the Basic Research Program of Jiangsu(Nos.BK20233001 and BK20241253)the Jiangsu Funding Program for Excellent Postdoctoral Talent(Nos.2024ZB002 and 2024ZB075)the Postdoctoral Fellowship Program of CPSF(No.GZC20240695)the AI&AI for the Science Program of Nanjing University,and the Fundamental Research Funds for the Central Universities,as well as the computational resources provided by the High Performance Computing Center of Collaborative Innovation Center of Advanced Microstructures and the highperformance supercomputing center of Nanjing University.P.Guan acknowledges the financial support by the National Natural Science Foundation of China(No.T2325004)E.Lindgren,T.Hainer,L.Svensson.,J.Wiktor,E.Berger,and P.Erhart gratefully acknowledge funding from the Swedish Foundation for Strategic Research(GSn15-0008 and FFL21-0129)the Swedish Research Council(Nos.2020-04935 and 2021-05072)the Knut and Alice Wallenberg Foundation(Nos.2023.0032 and 2024.0042)the European Research Council(ERC Starting Grant No.101162195)as well as computational resources provided by the National Academic Infrastructure for Supercomputing in Sweden at NSC,PDC,and C3SE partially funded by the Swedish Research Council through grant agreement no.2022-06725,as well as the Berzelius resource provided by the Knut and Alice Wallenberg Foundation at NSC.T.A-N.and Y.W.have been supported in part by the Academy of Finland through its QTF Center of Excellence program(project no.312298)European Union-NextGenerationEU instrument grant 353298.Computational resources by the CSC IT Center for Finland and the Aalto Science-IT are also gratefully acknowledged.
文摘This paper provides a comprehensive overview of the latest stable release of the graphics processing units molecular dynamics(GPUMD)package,GPUMD 4.0.We begin with a brief review of its development history,starting from the initial version.We then discuss the theoretical foundations for the development of the GPUMD package,including the formulations of the interatomic force,virial and heat current for many-body potentials,the development of the highly efficient and flexible neuroevolution potential(NEP)method,the supported integrators and related operations,the various physical properties that can be calculated on the fly,and the GPUMD ecosystem.After presenting these functionalities,we review a range of applications enabled by GPUMD,particularly in combination with the NEP approach.Finally,we outline possible future development directions for GPUMD.
基金This work was supported by the Ministry of Science and Technology of China(No.2018YFA0209102)the National Natural Science Foundation of China(Nos.11727807,51725101,51672050 and 61790581)the Science and Technology Commission of Shanghai Municipality(No.l6DZ2260600).
文摘Carbon-sulfur composites have draw n in creasing interest in various fields including electrocatalysis because of their unique structures.However,carb on-sulfur composite with tiny sulfur nano crystals has still received little attention.Herein,hollow porous carb on sphere-sulfur composite(HPCS-S)which possesses excellent electrochemical performance towards H2O2 has been prepared for the first time via a simple silica template method.The 2-5 nm sulfur nan ocrystals being restricted in the cha nnel of the hollow porous carb on spheres are un der a strong compressive stress,which was further con firmed by high-resoluti on tran smissi on electr on microscopy(HRTEM)and GPA.The HPCS-S nano crystals show better con ductivity tha n amorphous sulfur clusters because of the reducti on of the steric hindrance which efficie ntly promotes the electron transportation.Consequently,the higher activity and selectivity towards the 2e^oxygen reduction reaction(ORR)to H2O2 in alkaline solution was obtained.The H2O2 selectivity rises from 20%to over 70%after the sulfur addition and the H2O2 production rate achieves 183.99 mmol-gcataiyst-1 with the Faradaic efficiency of 70%.Furthermore,performance enhancement mechanism was also investigated using the den sity functional theory(DFT)calculatio ns.After the in troduci ng of sulfur nano crystals,the appeara nee of S-S bond greatly decreases the overpotential compared with S-doping,which results in significant enhancement of the electrocatalytic property.Consequently,the HPCS-S can be an efficient H2O2 production electrocatalyst in alkaline solution.
基金supported by the Natural Science Foundation of Guangdong Province(No.2020A1515011369).
文摘Growth plate cartilage has limited self-repair ability,leading to poor bone bridge formation post-injury and ultimately limb growth defects in children.The current corrective surgeries are highly invasive,and outcomes can be unpredictable.Following growth plate injury,the direct loss of extracellular matrix(ECM)coupled with further ECM depletion due to the inhibitory effects of inflammation on the cartilage matrix protein greatly hinder chondrocyte regeneration.We designed an exosome(Exo)derived from bone marrow mesenchymal stem cells(BMSCs)loaded ECM-mimic hydrogel to promote cartilage repair by directly supplementing ECM and anti-inflammatory properties.Aldehyde-functionalized chondroitin sulfate(OCS)was introduced into gelatin methacryloyl(GM)to form GMOCS hydrogel.Our results uncovered that GMOCS hydrogel could significantly promote the synthesis of ECM due to the doping of OCS.In addition,the GMOCS-Exos hydrogel could further promote the anabolism of chondrocytes by inhibiting inflammation and ultimately promote growth plate injury repair through ECM remodeling.
基金This work was supported by the the National Natural Science Foundation of China(Nos.51932002,51903087,51772106,31771080)the Natural Science Foundation of Guangdong Province(No.2020A1515011369)+2 种基金the Science and Technology Program of Guangzhou(No.202002030308)the Science and Technology Innovation Team Project of Foshan(No.2018IT100101)Sino-Singapore International Joint Research Institute(No.203-A018004).
文摘The host immune response effecting on biomaterials is critical to determine implant fates and bone regeneration property.Bone marrow stem cells(BMSCs)derived exosomes(Exos)contain multiple biosignal molecules and have been demonstrated to exhibit immunomodulatory functions.Herein,we develop a BMSC-derived Exos-functionalized implant to accelerate bone integration by immunoregulation.BMSC-derived Exos were reversibly incorporated on tannic acid(TA)modified sulfonated polyetheretherketone(SPEEK)via the strong interaction of TA with biomacromolecules.The slowly released Exos from SPEEK can be phagocytosed by co-cultured cells,which could efficiently improve the biocompatibilities of SPEEK.In vitro results showed the Exos loaded SPEEK promoted macrophage M2 polarization via the NF-κB pathway to enhance BMSCs osteogenic differentiation.Further in vivo rat air-pouch model and rat femoral drilling model assessment of Exos loaded SPEEK revealed efficient macrophage M2 polarization,desirable new bone formation,and satisfactory osseointegration.Thus,BMSC-derived Exos-functionalized implant exerted osteoimmunomodulation effect to promote osteogenesis.
基金We thank L.Fan for his help in drawing the schematic diagram and typesetting figures.This work was supported by the National Natural Science Foundation of China(Nos.51932002,51903087,and 31771080)the Science and Technology Innovation Team Project of Foshan(No.2018IT100101)+1 种基金Sino-Singapore International Joint Research Institute(No.203-A018004)and the Joint Fund of Ministry of Education for Equipment Preresearch(No.6141A02022632).
文摘Injectable biomaterial-based treatment is a promising strategy to enhance tissue repair after traumatic spinal cord injury(SCI)by bridging cavity spaces.However,there are limited reports of injectable,electroconductive hydrogels with self-healing properties being employed for the treatment of traumatic SCI.Hence,a natural extracellular matrix(ECM)biopolymer(chondroitin sulphate and gelatin)-based hydrogel containing polypyrrole,which imparted electroconductive properties,is developed for traumatic SCI repair.The resulting hydrogels showed mechanical(~928 Pa)and conductive properties(4.49 mS/cm)similar to natural spinal cord tissues.Moreover,the hydrogels exhibited shear-thinning and self-healing abilities,which allows it to be effectively injected into the injury site and to fill the lesion cavity to accelerate the tissue repair of traumatic SCI.In vitro,electroconductive ECM hydrogels promoted neuronal differentiation,enhanced axon outgrowth,and inhibited astrocyte differentiation.The electroconductive ECM hydrogel activated endogenous neural stem cell neurogenesis in vivo(n=6),and induced myelinated axon regeneration into the lesion site via activation of the PI3K/AKT and MEK/ERK pathways,thereby achieving significant locomotor function restoration in rats with spinal cord injury(p<0.001,compared to SCI group).Overall,the injectable self-healing electroconductive ECM-based hydrogels developed in this study are ideal biomaterials for treatment of traumatic SCI.
基金Project supported by the NSERC Discovery Grant, the Fok Ying Tung Eduction Foundation the National Natural Science Foundation of China (No.10371041) Hundred Talents Program of Chinese Academy of Sciences.
文摘In this paper the authors discuss the existence and convexity of hypersurfaces with prescribed Weingarten curvature.
基金supported by the National Natural Science Foundation of China Joint Program(U1930402)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB30000000)+1 种基金the National Key Research and Development Plan(2018YFA0703603)the Natural Science Foundation of Guangdong Province(2019B030302010)。
文摘In crystalline solids,plastic deformation is determined by the motion of structural defects,particularly dislocations.As for glassy liquids and disordered solids,it has long been assumed that localized structural rearrangements induced by mechanical load or thermal stimulus also occur at localized defects[1-3].
基金supported by the Science Challenge Project (TZ2018004)the NSAF joint Program (U1930402)computational support from Beijing Computational Research Center (CSRC)
文摘Computational simulation provides an effective way of understanding the disordered structure and structureproperty relationships for metallic glass systems.Here,we systematically investigated the finite-size effects of the static structure and dynamical behaviors in a three-dimensional Cu50Zr50 model metallic glass via classical molecular dynamics(MD)simulations.It was found that the local structure is insensitive to the system size while the dynamical properties present evident finite-size effects.The decoupling between local structure and relaxation dynamics in the investigated supercooling emerges when the system contains less than~2000 atoms.However,the collapse can be observed between the structural relaxation time and the dynamical heterogeneity for different sized systems across the whole range of our investigation.Our results support the intrinsic link between the structural relaxation time and dynamic heterogeneity and reveal the critical simulated system size for representing the structural origins of dynamics in bulk metallic glass with ignorable surface effects.
基金the National Key Research and Development Program of China(2017YFA0105400)the National Natural Science Foundation of China(82072455,81772349,31470949)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(2019A1515012181,2017A030313594)the Guangzhou Science and Technology Planning Project of China(201707010115).
文摘Conductive scaffolds have been shown to exert a therapeutic effect on patients suffering from peripheral nerve injuries(PNIs).However,conventional conductive conduits are made of rigid structures and have limited applications for impaired diabetic patients due to their mechanical mismatch with neural tissues and poor plasticity.We propose the development of biocompatible electroconductive hydrogels(ECHs)that are identical to a surgical dressing in this study.Based on excellent adhesive and self-healing properties,the thin film-like dressing can be easily attached to the injured nerve fibers,automatically warps a tubular structure without requiring any invasive techniques.The ECH offers an intimate and stable electrical bridge coupling with the electrogenic nerve tissues.The in vitro experiments indicated that the ECH promoted the migration and adhesion of the Schwann cells.Furthermore,the ECH facilitated axonal regeneration and remyelination in vitro and in vivo through the MEK/ERK pathway,thus preventing muscle denervation atrophy while retaining functional recovery.The results of this study are likely to facilitate the development of non-invasive treatment techniques for PNIs in diabetic patients utilizing electroconductive hydrogels.
基金sponsored by the National Natural Science Foundation of China (Grant No. 52101201)supported by the National Natural Science Foundation of China (Grant No.T2325004)+2 种基金sponsored by the National Natural Science Foundation of China(Grant No. 51801046)the Natural Science Foundation of Chongqing,China (Grant No. cstc2021jcyj-msxm X0369)the Science Fund for Scientific and Technological Innovation Team of Shaanxi Province (Grant No. 2021TD-14)。
文摘The fast dynamic properties of the surface of metallic glasses(MGs) play a critical role in determining their potential applications. However, due to the significant difference in thermal history between atomic simulation models and laboratory-made samples, the atomic-scale behaviors of the fast surface dynamics of MGs in experiments remain uncertain. Herein, we prepared model MG films with notable variations in thermal stability using a recently developed efficient annealing protocol, and investigated their atomic-scale dynamics systematically. We found that the dynamics of surface atoms remain invariant, whereas the difference in dynamical heterogeneity between surface and interior regions increases with the improvement of thermal stability. This can be associated with the more pronounced correlation between atomic activation energy spectra and depth from the surface in samples with higher thermal stability. In addition, dynamic anisotropy appears for surface atoms, and their transverse dynamics are faster than normal components, which can also be interpreted by activation energy spectra. Our results reveal the presence of strong liquid-like atomic dynamics confined to the surface of laboratory-made MGs, illuminating the underlying mechanisms for surface engineering design, such as cold joining by ultrasonic vibrations and superlattice growth.
基金supported by the National Natural Science Foundation of China(U2230402,T2325004).
文摘Single oxygen diffusion event,the most favorable rate-limiting process of epitaxial Cu_(2)O oxide-island layerby-layer growth kinetics,may lead to oxygen defects due to thermomechanical coupling.However,the formation rules of oxygen defects remain unclear,preventing the realization of controllable oxygen defects on oxide-island surfaces.Here,we utilize the first-principles method to investigate the formation rules of intrinsic oxygen defects in the surface layers of prototypical metal-oxide(Cu_(2)O)surfaces under thermomechanical coupling effects.We establish the thermodynamic phase diagram for oxygen-defect-modulated Cu_(2)O surfaces,enabling the prediction of the growth of oxide islands during Cu oxidation,which aligns closely with in-situ environmental transmission electron microscopy(ETEM)experiment observations.By exploring the strain-modulated phase diagrams,we propose a potential strategy for controlling the type and concentration of oxygen defects on oxide-island surfaces.Our findings provide an effective approach to theoretically understanding the oxidation process of metal surfaces,thus enabling the computational design of high-performance corrosion-resistant surfaces.
基金supported by the National Natural Science Foundation of China(Grant Nos.51901139,U1902221,51971120,and 51971093)the Taishan Scholars Program of Shandong Province(Grant No.tsqn201909010)the Key Basic and Applied Research Program of Guangdong Province(Grant No.2019B030302010)。
文摘As a common but critical dynamic crossover in glass-forming liquids(GFLs),the discovery of fragile-to-strong(F-S)transition promises a novel route for understanding supercooled liquid and glass transition.The present work,for the first time,successfully realizes the quantitative prediction of the F-S transition in nine metallic glass-forming liquids,by a counter-intuitive approach that focuses on local atomic activation events,rather than relaxation,upon cooling.The dynamic crossover originates from a disorder-to-order transition by self-regulating behavior of atomic position within a cage controlled by finite atomic activation events,due to the appearance of local cooperative motion of nearest neighborhood atoms.Moreover,the dominant role of entropy in this anomaly has been discovered,and the correspondence between the crossover of configuration entropy involved in activation events and the occurrence of F-S transition has been found.Our work implies that the feature of atomic energy fluctuations reflected by atomic activation events has a close linkage to complex dynamic behaviors of disordered systems.
