The aging of biomolecular condensates has been implicated in the pathogenesis of various neurodegenerative diseases,characterized by a transition from a physiologically liquid-like state to a pathologically ordered st...The aging of biomolecular condensates has been implicated in the pathogenesis of various neurodegenerative diseases,characterized by a transition from a physiologically liquid-like state to a pathologically ordered structure.However,the mechanisms governing the formation of these pathological aggregates remain poorly understood.To address this,the present study utilizes coarse-grained molecular dynamics simulations based on Langevin dynamics to explore the structural,dynamical,and material property changes of protein condensates during the aging process.Here,we further develop a nonequilibrium simulation algorithm that not only captures the characteristics of time-dependent amount of aging beads but also reflects the structural information of chain-like connections between aging beads.Our findings reveal that aging induces compaction of the condensates,accompanied by a decrease in diffusion rates and an increase in viscosity.Further analysis suggests that the heterogeneous diffusivity within the condensates may drive the aging process to initiate preferentially at the condensate surface.Our simulation results align with the experimental phenomena and provide a clear physical picture of the aging dynamics.展开更多
The spinodal decomposition method emerges as a promising methodology,showcasing its potential in exploring the design space for metamaterial structures.However,spinodal structures design is still largely limited to re...The spinodal decomposition method emerges as a promising methodology,showcasing its potential in exploring the design space for metamaterial structures.However,spinodal structures design is still largely limited to regular structures,due to their relatively easy parameterization and controllability.Efficiently predicting the mechanical properties of 3D spinodal membrane structure remains a challenge,given that the features of the membrane necessitate adaptive mesh through the modelling process.This paper proposes an integrated approach for morphological design with customized mechanical properties,incorporating the spinodal decomposition method and adaptive coarse-grained modeling,which can produce various morphologies such as lamellar,columnar,and cubic structures.Pseudo-periodic parameterβand orientational parameterΘ(θ_(1),θ_(2),θ_(3))are identified to achieve the optimal goal of anisotropic mechanical properties.Parametric analysis is conducted to reveal the correlation between the customized spinodal structure and mechanical performance.Our work provides an integrated approach for morphological variation and tuning mechanical properties,paving the way for the design and development of customized functional materials similar to 3D spinodal membrane structures.展开更多
The secondary structure of different Iβ cellulose was analyzed by a molecular dynamics sim- ulation with MARTINI coarse-grained force field, where each chain of the cellulose includes 40 D-glucoses units. Calculation...The secondary structure of different Iβ cellulose was analyzed by a molecular dynamics sim- ulation with MARTINI coarse-grained force field, where each chain of the cellulose includes 40 D-glucoses units. Calculation gives a satisfied description about the secondary structure of the cellulose. As the chain number increasing, the cellulose becomes the form of a helix, with the diameter of screw growing and spiral rising. Interestingly, the celluloses with chain number N of 4, 6, 24 and 36 do show right-hand twisting. On the contrast, the celluloses with N of 8, 12, 16 chains are left-hand twisting. These simulations indicate that the cellulose with chain number larger than 36 will break down to two parts. Besides, the result indicates that 36-chains cellulose model is the most stable among all models. Furthermore, the Lennard-Jones potential determines the secondary structure. In addition, an equation was set up to analyze the twisting structure.展开更多
The present work proposes a novel methodology for constructing coarse-grained （CG） models, which aims at minimizing the difference between CG model and the corresponding original system. The difference is defined as...The present work proposes a novel methodology for constructing coarse-grained （CG） models, which aims at minimizing the difference between CG model and the corresponding original system. The difference is defined as a functional of their equilibrium conformationaJ probability densities, then is estimated from equilibrium averages of many independent physical quantities denoted as basis functions. An orthonormalization strategy is adopted to get the independent basis functions from su^ciently preselected interesting physical quantities of the system. Thus the current method is named as probability density matching coarse-graining （PMCG） scheme, which effectively takes into account the overall cha,~acteristics of the original systems to construct CG model, and it is a rtatural improvement of the usual CG scheme wherein some physical quantities are intuitively chosen without considering their correlations. We verify the general PMCG framework in constructing a one-site CG water model from TIP3P model. Both structure of liquids and pressure of the TIP3P water system are found to be well reproduced at the same time in the constructed CG model.展开更多
Seepage in coarse-grained soil exhibits distinct non-Darcy characteristics,and the transition from linear to nonlinear seepage significantly affects the hydraulic characteristics and geotechnical applications.Due to t...Seepage in coarse-grained soil exhibits distinct non-Darcy characteristics,and the transition from linear to nonlinear seepage significantly affects the hydraulic characteristics and geotechnical applications.Due to the complexity of pore structure in heterogeneous coarse-grained soil,identifying the critical threshold for the transition from Darcy to non-Darcy seepage is challenging.This paper introduces equivalent particle size(dep)and relative roughness(λt)as indirect indicators reflecting the pore characteristics,quantifying the complex pore structure of heterogeneous coarse-grained soil.The formulae for the derivation of Reynolds number and resistance coefficient for heterogeneous coarse-grained soil are presented.By conducting permeability tests on coarse-grained soils with different pore structures,the effect of particle composition heterogeneity on seepage characteristics was analyzed.The flow regime of heterogeneous coarse-grained soil is divided into laminar,transitional,and turbulent stages based on the relationship between Reynolds number and resistance coefficient.The energy loss patterns in each stage are closely related to pore structure.By setting the permeability ratio k∗=0.95 as the critical threshold for the transition from Darcy to non-Darcy seepage,a method for calculating the critical Reynolds number(Recr)for heterogeneous coarse-grained soil is proposed.Furthermore,we applied this method to other published laboratory data,analyzing the differences in the critical threshold for seepage transition between homogeneous and heterogeneous coarse-grained soil.This study aims to propose a more accurate and general criterion for the transition from Darcy to non-Darcy seepage in heterogeneous coarse-grained soil.展开更多
To overcome the limitations of microscale experimental techniques and molecular dynamics(MD)simulations,a coarse-grained molecular dynamics(CGMD)method was used to simulate the wetting processes of clay aggregates.Bas...To overcome the limitations of microscale experimental techniques and molecular dynamics(MD)simulations,a coarse-grained molecular dynamics(CGMD)method was used to simulate the wetting processes of clay aggregates.Based on the evolution of swelling stress,final dry density,water distribution,and clay arrangements under different target water contents and dry densities,a relationship between the swelling behaviors and microstructures was established.The simulated results showed that when the clay-water well depth was 300 kcal/mol,the basal spacing from CGMD was consistent with the X-ray diffraction(XRD)data.The effect of initial dry density on swelling stress was more pronounced than that of water content.The anisotropic swelling characteristics of the aggregates are related to the proportion of horizontally oriented clay mineral layers.The swelling stress was found to depend on the distribution of tactoids at the microscopic level.At lower initial dry density,the distribution of tactoids was mainly controlled by water distribution.With increase in the bound water content,the basal spacing expanded,and the swelling stresses increased.Free water dominated at higher water contents,and the particles were easily rotated,leading to a decrease in the number of large tactoids.At higher dry densities,the distances between the clay mineral layers decreased,and the movement was limited.When bound water enters the interlayers,there is a significant increase in interparticle repulsive forces,resulting in a greater number of small-sized tactoids.Eventually,a well-defined logarithmic relationship was observed between the swelling stress and the total number of tactoids.These findings contribute to a better understanding of coupled macro-micro swelling behaviors of montmorillonite-based materials,filling a study gap in clay-water interactions on a micro scale.展开更多
This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two exp...This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two experimental shipbuilding steels after being subjected to high-heat input welding at 400 kJ·cm^(-1).The base metals (BMs) of both steels contained three types of precipitates Type Ⅰ:cubic (Ti,Nb)(C,N),Type Ⅱ:precipitate with cubic (Ti,Nb)(C,N) core and Nb-rich cap,and Type Ⅲ:ellipsoidal Nb-rich precipitate.In the BM of 60Al and 160Al steels,the number densities of the precipitates were 11.37×10^(5) and 13.88×10^(5) mm^(-2),respectively The 60Al and 160Al steel contained 38.12% and 6.39% Type Ⅲ precipitates,respectively.The difference in the content of Type Ⅲ precipitates in the 60Al steel reduced the pinning effect at the elevated temperature of the CGHAZ,which facilitated the growth of PAGs The average PAG sizes in the CGHAZ of the 60Al and 160Al steels were 189.73 and 174.7μm,respectively.In the 60Al steel,the low lattice mismatch among Cu_(2)S,TiN,and γ-Al_(2)O_(3)facilitated the precipitation of Cu_(2)S and TiN onto γ-Al_(2)O_(3)during welding,which decreased the number density of independently precipitated (Ti,Nb)(C,N) particles but increased that of γ-Al_(2)O_(3)–Ti N–Cu_(2)S particles.Thus abnormally large PAGs formed in the CGHAZ of the 60Al steel,and they reached a maximum size of 1 mm.These PAGs greatly reduced the microstructural homogeneity and consequently decreased the impact toughness from 134 (0.016wt%Al) to 54 J (0.006wt%Al)at-40℃.展开更多
This study investigated the hydraulic and mechanical behaviors of unsaturated coarse-grained railway embankment fill materials(CREFMs)using a novel unsaturated large-scale triaxial apparatus equipped with the axis tra...This study investigated the hydraulic and mechanical behaviors of unsaturated coarse-grained railway embankment fill materials(CREFMs)using a novel unsaturated large-scale triaxial apparatus equipped with the axis translation technique(ATT).Comprehensive soil-water retention and constant-suction triaxial compression tests were conducted to evaluate the effects of initial void ratio,matric suction,and confining pressure on the properties of CREFMs.Key findings reveal a primary suction range of 0 e100 kPa characterized by hysteresis,which intensifies with decreasing density.Notably,the air entry value and residual suction are influenced by void ratio,with higher void ratios leading to decreased air entry values and residual suctions,underscoring the critical role of void ratio in hydraulic behavior.Additionally,the critical state line(CSL)in the bi-logarithmic space of void ratio and mean effective stress shifts towards higher void ratios with increasing matric suction,significantly affecting dilatancy and critical states.Furthermore,the study demonstrated that the mobilized friction angle and modulus properties depend on confining pressure and matric suction.A novel modified dilatancy equation was proposed,which enhances the predictability of CREFMs'responses under variable loading,particularly at high stress ratios defined by the deviatoric stress over the mean effective stress.This research advances the understanding of CREFMs'performance,especially under fluctuating environmental conditions that alter suction levels.展开更多
A generic coarse-grained bead-and-spring model,mapped onto comb-shaped polycarboxylate-based(PCE)superplasticizers,is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit...A generic coarse-grained bead-and-spring model,mapped onto comb-shaped polycarboxylate-based(PCE)superplasticizers,is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions.The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution.The effects of ionic strength,side-chain number,and side-chain length on the conformational behavior of PCEs in solution are explored.Single-chain equilibrium properties,including the radius of gyration,end-to-end distance and persistenee length of the polymer backbone,shape-asphericity parameter,and the mean span dimension,are determined.It is found that with the increase of ionic strength,the equilibrium sizes of the polymers decrease only slightly,and a linear dependenew of the persistence length of backbone on the Debye screening length is found,in good agreement with the theory developed by Dobrynin.Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes(radius of gyration and mean span)of the polymer as a whole,but also the persistence length of the backbone due to excluded volume interactions.展开更多
The effects of ultrafine WC(WC_(UF),0.5μm) or W(1μm) and C(0.3μm)(W+C)_(UF) additives on the densification,microstructure and mechanical properties of coarse-grained cemented carbides were compared systematically.O...The effects of ultrafine WC(WC_(UF),0.5μm) or W(1μm) and C(0.3μm)(W+C)_(UF) additives on the densification,microstructure and mechanical properties of coarse-grained cemented carbides were compared systematically.Overall,the cemented carbides with WC_(UF)/(W+C)_(UF) additives are almost fully densification to be higher than 99%,and the average grain size is kept above 2.8μm.The WC_(UF) additive assists grains to(truncated)trigonal prism shape by two dimensional(2D) growth,whereas the(W+C)_(UF) additive assists grains to rounded shape by three dimensional(3D) growth,lowers WC contiguity and increases face-centered-cubic Co.The hardness and bending strength of(75WC_(C)-15WC_(UF))-10Co are 86.6 HRA and 2 272 MPa,respectively,both higher than those of(75WC_(C)-15(W+C)_(UF))-10Co,which could be ascribed to the enhanced densification and unblemished grains.However,the fracture toughness of the(75WC_(C)-15(W+C)_(UF))-10Co is 23.5 MPa·m^(1/2),higher than that of the(75WC_(C)-15WC_(UF))-10Co due to the uniform WC-Co structure and flexible binder phase.展开更多
The assembly of a protein complex is very important for its biological function,which can be investigated by determining the order of assembly/disassembly of its protein subunits.Although static structures of many pro...The assembly of a protein complex is very important for its biological function,which can be investigated by determining the order of assembly/disassembly of its protein subunits.Although static structures of many protein com-plexes are available in the protein data bank,their assembly/disassembly orders of subunits are largely unknown.In addition to experimental techniques for studying subcomplexes in the assembly/disassembly of a protein complex,computational methods can be used to predict the assembly/disassembly order.Since sampling is a nontrivial issue in simulating the assembly/disassembly process,coarse-grained simulations are more efficient than atomic simulations are.In this work,we developed computational protocols for predicting the assembly/disassembly orders of protein complexes via coarse-grained simulations.The protocols were illustrated via two protein complexes,and the predicted assembly/disassembly orders were consistent with the available experimental data.展开更多
We simulated rapid flow in transient plane Couette flows of granular particles using the smoothed particle hydrodynamics （SPH） solutions of a set of continuum equations, This simulation was performed to test the via...We simulated rapid flow in transient plane Couette flows of granular particles using the smoothed particle hydrodynamics （SPH） solutions of a set of continuum equations, This simulation was performed to test the viability of SPH in solving the equations for the solid phase of the two-fluid model associated with fluidization. We found that SPH requires the handling of fewer particles in simulating the collective behavior of rapid granular flow, thereby bolstering expectations of solving the equations for the solid phase in the two-fluid modeling of fluidization. Further work is needed to investigate the effect of terms describing pressure and viscous stress of solids on stability in simulations.展开更多
In this work, the previously developed coarse-grained （CG） particle models for biomembranes and red blood cells （RBCs） are reviewed, and the advantages of the CG particle methods over the continuum and atomistic s...In this work, the previously developed coarse-grained （CG） particle models for biomembranes and red blood cells （RBCs） are reviewed, and the advantages of the CG particle methods over the continuum and atomistic simulations for modeling biological phenomena are discussed. CG particle models can largely increase the length scale and time scale of atomistic simulations by eliminating the fast degrees of freedom while preserving the mesoscopic structures and properties of the simulated system. Moreover, CG particle models can be used to capture the microstructural alternations in diseased RBCs and simulate the topological changes of biomembranes and RBCs, which are the major challenges to the typical continuum representations of membranes and RBCs. The power and versatility of CG particle methods are demonstrated：through simulating the dynamical processes mvolving significant topological .changes e.g. lipid self-assembly vesicle fusion and membrane budding.展开更多
BACKGROUND Rebleeding after recovery from esophagogastric variceal bleeding(EGVB)is a severe complication that is associated with high rates of both incidence and mortality.Despite its clinical importance,recognized p...BACKGROUND Rebleeding after recovery from esophagogastric variceal bleeding(EGVB)is a severe complication that is associated with high rates of both incidence and mortality.Despite its clinical importance,recognized prognostic models that can effectively predict esophagogastric variceal rebleeding in patients with liver cirrhosis are lacking.AIM To construct and externally validate a reliable prognostic model for predicting the occurrence of esophagogastric variceal rebleeding.METHODS This study included 477 EGVB patients across 2 cohorts:The derivation cohort(n=322)and the validation cohort(n=155).The primary outcome was rebleeding events within 1 year.The least absolute shrinkage and selection operator was applied for predictor selection,and multivariate Cox regression analysis was used to construct the prognostic model.Internal validation was performed with bootstrap resampling.We assessed the discrimination,calibration and accuracy of the model,and performed patient risk stratification.RESULTS Six predictors,including albumin and aspartate aminotransferase concentrations,white blood cell count,and the presence of ascites,portal vein thrombosis,and bleeding signs,were selected for the rebleeding event prediction following endoscopic treatment(REPET)model.In predicting rebleeding within 1 year,the REPET model ex-hibited a concordance index of 0.775 and a Brier score of 0.143 in the derivation cohort,alongside 0.862 and 0.127 in the validation cohort.Furthermore,the REPET model revealed a significant difference in rebleeding rates(P<0.01)between low-risk patients and intermediate-to high-risk patients in both cohorts.CONCLUSION We constructed and validated a new prognostic model for variceal rebleeding with excellent predictive per-formance,which will improve the clinical management of rebleeding in EGVB patients.展开更多
This study was aimed to prepare landslide susceptibility maps for the Pithoragarh district in Uttarakhand,India,using advanced ensemble models that combined Radial Basis Function Networks(RBFN)with three ensemble lear...This study was aimed to prepare landslide susceptibility maps for the Pithoragarh district in Uttarakhand,India,using advanced ensemble models that combined Radial Basis Function Networks(RBFN)with three ensemble learning techniques:DAGGING(DG),MULTIBOOST(MB),and ADABOOST(AB).This combination resulted in three distinct ensemble models:DG-RBFN,MB-RBFN,and AB-RBFN.Additionally,a traditional weighted method,Information Value(IV),and a benchmark machine learning(ML)model,Multilayer Perceptron Neural Network(MLP),were employed for comparison and validation.The models were developed using ten landslide conditioning factors,which included slope,aspect,elevation,curvature,land cover,geomorphology,overburden depth,lithology,distance to rivers and distance to roads.These factors were instrumental in predicting the output variable,which was the probability of landslide occurrence.Statistical analysis of the models’performance indicated that the DG-RBFN model,with an Area Under ROC Curve(AUC)of 0.931,outperformed the other models.The AB-RBFN model achieved an AUC of 0.929,the MB-RBFN model had an AUC of 0.913,and the MLP model recorded an AUC of 0.926.These results suggest that the advanced ensemble ML model DG-RBFN was more accurate than traditional statistical model,single MLP model,and other ensemble models in preparing trustworthy landslide susceptibility maps,thereby enhancing land use planning and decision-making.展开更多
Conducting predictability studies is essential for tracing the source of forecast errors,which not only leads to the improvement of observation and forecasting systems,but also enhances the understanding of weather an...Conducting predictability studies is essential for tracing the source of forecast errors,which not only leads to the improvement of observation and forecasting systems,but also enhances the understanding of weather and climate phenomena.In the past few decades,dynamical numerical models have been the primary tools for predictability studies,achieving significant progress.Nowadays,with the advances in artificial intelligence(AI)techniques and accumulations of vast meteorological data,modeling weather and climate events using modern data-driven approaches is becoming trendy,where FourCastNet,Pangu-Weather,and GraphCast are successful pioneers.In this perspective article,we suggest AI models should not be limited to forecasting but be expanded to predictability studies,leveraging AI's advantages of high efficiency and self-contained optimization modules.To this end,we first remark that AI models should possess high simulation capability with fine spatiotemporal resolution for two kinds of predictability studies.AI models with high simulation capabilities comparable to numerical models can be considered to provide solutions to partial differential equations in a data-driven way.Then,we highlight several specific predictability issues with well-determined nonlinear optimization formulizations,which can be well-studied using AI models,holding significant scientific value.In addition,we advocate for the incorporation of AI models into the synergistic cycle of the cognition–observation–model paradigm.Comprehensive predictability studies have the potential to transform“big data”to“big and better data”and shift the focus from“AI for forecasts”to“AI for science”,ultimately advancing the development of the atmospheric and oceanic sciences.展开更多
With the development of smart cities and smart technologies,parks,as functional units of the city,are facing smart transformation.The development of smart parks can help address challenges of technology integration wi...With the development of smart cities and smart technologies,parks,as functional units of the city,are facing smart transformation.The development of smart parks can help address challenges of technology integration within urban spaces and serve as testbeds for exploring smart city planning and governance models.Information models facilitate the effective integration of technology into space.Building Information Modeling(BIM)and City Information Modeling(CIM)have been widely used in urban construction.However,the existing information models have limitations in the application of the park,so it is necessary to develop an information model suitable for the park.This paper first traces the evolution of park smart transformation,reviews the global landscape of smart park development,and identifies key trends and persistent challenges.Addressing the particularities of parks,the concept of Park Information Modeling(PIM)is proposed.PIM leverages smart technologies such as artificial intelligence,digital twins,and collaborative sensing to help form a‘space-technology-system’smart structure,enabling systematic management of diverse park spaces,addressing the deficiency in park-level information models,and aiming to achieve scale articulation between BIM and CIM.Finally,through a detailed top-level design application case study of the Nanjing Smart Education Park in China,this paper illustrates the translation process of the PIM concept into practice,showcasing its potential to provide smart management tools for park managers and enhance services for park stakeholders,although further empirical validation is required.展开更多
To examine the similarities and differences in the evolution of cavity,wetting and dynamics of a highspeed,oblique water-entry projectile with different positive angles of attack,a comparative analysis has been conduc...To examine the similarities and differences in the evolution of cavity,wetting and dynamics of a highspeed,oblique water-entry projectile with different positive angles of attack,a comparative analysis has been conducted based on the numerical results of two mathematical models,the rigid-body model and fluid-structure interaction model.In addition,the applicable scope of the above two methods,and the structural response characteristics of the projectile have also been investigated.Our results demonstrate that:(1) The impact loads and angular motion of the projectile of the rigid-body method are more likely to exhibit periodic variations due to the periodic tail slap,its range of positive angles of attack is about α<2°.(2) When the projectile undergone significant wetting,a strong coupling effect is observed among wetting,structural deformation,and projectile motion.With the applied projectile shape,it is observed that,when the projectile bends,the final wetting position is that of Part B(cylinder of body).With the occu rrence of this phenomenon,the projectile ballistics beco me completely unstable.(3) The force exerted on the lower surface of the projectile induced by wetting is the primary reason of the destabilization of the projectile traj ectory and structu ral deformation failure.Bending deformation is most likely to appear at the junction of Part C(cone of body) and Part D(tail).The safe angles of attack of the projectile stability are found to be about α≤2°.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1405000)the National Natural Science Foundation of China(Grant Nos.12274212,12347102,and 12174184)Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300101).
文摘The aging of biomolecular condensates has been implicated in the pathogenesis of various neurodegenerative diseases,characterized by a transition from a physiologically liquid-like state to a pathologically ordered structure.However,the mechanisms governing the formation of these pathological aggregates remain poorly understood.To address this,the present study utilizes coarse-grained molecular dynamics simulations based on Langevin dynamics to explore the structural,dynamical,and material property changes of protein condensates during the aging process.Here,we further develop a nonequilibrium simulation algorithm that not only captures the characteristics of time-dependent amount of aging beads but also reflects the structural information of chain-like connections between aging beads.Our findings reveal that aging induces compaction of the condensates,accompanied by a decrease in diffusion rates and an increase in viscosity.Further analysis suggests that the heterogeneous diffusivity within the condensates may drive the aging process to initiate preferentially at the condensate surface.Our simulation results align with the experimental phenomena and provide a clear physical picture of the aging dynamics.
基金supported by the National Natural Science Foundation of China(Grant No.11872278)the Science and Technology Commission of Shanghai Municipality(Grant No.21ZR1467200)the Fundamental Research Funds for the Central Universities.
文摘The spinodal decomposition method emerges as a promising methodology,showcasing its potential in exploring the design space for metamaterial structures.However,spinodal structures design is still largely limited to regular structures,due to their relatively easy parameterization and controllability.Efficiently predicting the mechanical properties of 3D spinodal membrane structure remains a challenge,given that the features of the membrane necessitate adaptive mesh through the modelling process.This paper proposes an integrated approach for morphological design with customized mechanical properties,incorporating the spinodal decomposition method and adaptive coarse-grained modeling,which can produce various morphologies such as lamellar,columnar,and cubic structures.Pseudo-periodic parameterβand orientational parameterΘ(θ_(1),θ_(2),θ_(3))are identified to achieve the optimal goal of anisotropic mechanical properties.Parametric analysis is conducted to reveal the correlation between the customized spinodal structure and mechanical performance.Our work provides an integrated approach for morphological variation and tuning mechanical properties,paving the way for the design and development of customized functional materials similar to 3D spinodal membrane structures.
文摘The secondary structure of different Iβ cellulose was analyzed by a molecular dynamics sim- ulation with MARTINI coarse-grained force field, where each chain of the cellulose includes 40 D-glucoses units. Calculation gives a satisfied description about the secondary structure of the cellulose. As the chain number increasing, the cellulose becomes the form of a helix, with the diameter of screw growing and spiral rising. Interestingly, the celluloses with chain number N of 4, 6, 24 and 36 do show right-hand twisting. On the contrast, the celluloses with N of 8, 12, 16 chains are left-hand twisting. These simulations indicate that the cellulose with chain number larger than 36 will break down to two parts. Besides, the result indicates that 36-chains cellulose model is the most stable among all models. Furthermore, the Lennard-Jones potential determines the secondary structure. In addition, an equation was set up to analyze the twisting structure.
基金Supported by National Natural Science Foundation of China under Grant No.11175250
文摘The present work proposes a novel methodology for constructing coarse-grained （CG） models, which aims at minimizing the difference between CG model and the corresponding original system. The difference is defined as a functional of their equilibrium conformationaJ probability densities, then is estimated from equilibrium averages of many independent physical quantities denoted as basis functions. An orthonormalization strategy is adopted to get the independent basis functions from su^ciently preselected interesting physical quantities of the system. Thus the current method is named as probability density matching coarse-graining （PMCG） scheme, which effectively takes into account the overall cha,~acteristics of the original systems to construct CG model, and it is a rtatural improvement of the usual CG scheme wherein some physical quantities are intuitively chosen without considering their correlations. We verify the general PMCG framework in constructing a one-site CG water model from TIP3P model. Both structure of liquids and pressure of the TIP3P water system are found to be well reproduced at the same time in the constructed CG model.
基金supported by the National Nature Science Foundation of China (Grant No.42072303)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (Grant No.SKLGP2021Z004).
文摘Seepage in coarse-grained soil exhibits distinct non-Darcy characteristics,and the transition from linear to nonlinear seepage significantly affects the hydraulic characteristics and geotechnical applications.Due to the complexity of pore structure in heterogeneous coarse-grained soil,identifying the critical threshold for the transition from Darcy to non-Darcy seepage is challenging.This paper introduces equivalent particle size(dep)and relative roughness(λt)as indirect indicators reflecting the pore characteristics,quantifying the complex pore structure of heterogeneous coarse-grained soil.The formulae for the derivation of Reynolds number and resistance coefficient for heterogeneous coarse-grained soil are presented.By conducting permeability tests on coarse-grained soils with different pore structures,the effect of particle composition heterogeneity on seepage characteristics was analyzed.The flow regime of heterogeneous coarse-grained soil is divided into laminar,transitional,and turbulent stages based on the relationship between Reynolds number and resistance coefficient.The energy loss patterns in each stage are closely related to pore structure.By setting the permeability ratio k∗=0.95 as the critical threshold for the transition from Darcy to non-Darcy seepage,a method for calculating the critical Reynolds number(Recr)for heterogeneous coarse-grained soil is proposed.Furthermore,we applied this method to other published laboratory data,analyzing the differences in the critical threshold for seepage transition between homogeneous and heterogeneous coarse-grained soil.This study aims to propose a more accurate and general criterion for the transition from Darcy to non-Darcy seepage in heterogeneous coarse-grained soil.
基金supported by the National Natural Science Foundation of China(Grant No.42172308)the Youth Innovation Promotion Association CAS(Grant No.2022331)the Key Research and Development Program of Hubei Province(Grant No.2022BAA036).
文摘To overcome the limitations of microscale experimental techniques and molecular dynamics(MD)simulations,a coarse-grained molecular dynamics(CGMD)method was used to simulate the wetting processes of clay aggregates.Based on the evolution of swelling stress,final dry density,water distribution,and clay arrangements under different target water contents and dry densities,a relationship between the swelling behaviors and microstructures was established.The simulated results showed that when the clay-water well depth was 300 kcal/mol,the basal spacing from CGMD was consistent with the X-ray diffraction(XRD)data.The effect of initial dry density on swelling stress was more pronounced than that of water content.The anisotropic swelling characteristics of the aggregates are related to the proportion of horizontally oriented clay mineral layers.The swelling stress was found to depend on the distribution of tactoids at the microscopic level.At lower initial dry density,the distribution of tactoids was mainly controlled by water distribution.With increase in the bound water content,the basal spacing expanded,and the swelling stresses increased.Free water dominated at higher water contents,and the particles were easily rotated,leading to a decrease in the number of large tactoids.At higher dry densities,the distances between the clay mineral layers decreased,and the movement was limited.When bound water enters the interlayers,there is a significant increase in interparticle repulsive forces,resulting in a greater number of small-sized tactoids.Eventually,a well-defined logarithmic relationship was observed between the swelling stress and the total number of tactoids.These findings contribute to a better understanding of coupled macro-micro swelling behaviors of montmorillonite-based materials,filling a study gap in clay-water interactions on a micro scale.
基金support from the National Natural Science Foundation of China (No. U1960202)the Opening Foundation from Shanghai Engineering Research Center of Hot Manufacturing, China (No. 18DZ2253400)。
文摘This work focuses on the influence of Al content on the precipitation of nanoprecipitates,growth of prior austenite grains(PAGs),and impact toughness in simulated coarse-grained heat-affected zones (CGHAZs) of two experimental shipbuilding steels after being subjected to high-heat input welding at 400 kJ·cm^(-1).The base metals (BMs) of both steels contained three types of precipitates Type Ⅰ:cubic (Ti,Nb)(C,N),Type Ⅱ:precipitate with cubic (Ti,Nb)(C,N) core and Nb-rich cap,and Type Ⅲ:ellipsoidal Nb-rich precipitate.In the BM of 60Al and 160Al steels,the number densities of the precipitates were 11.37×10^(5) and 13.88×10^(5) mm^(-2),respectively The 60Al and 160Al steel contained 38.12% and 6.39% Type Ⅲ precipitates,respectively.The difference in the content of Type Ⅲ precipitates in the 60Al steel reduced the pinning effect at the elevated temperature of the CGHAZ,which facilitated the growth of PAGs The average PAG sizes in the CGHAZ of the 60Al and 160Al steels were 189.73 and 174.7μm,respectively.In the 60Al steel,the low lattice mismatch among Cu_(2)S,TiN,and γ-Al_(2)O_(3)facilitated the precipitation of Cu_(2)S and TiN onto γ-Al_(2)O_(3)during welding,which decreased the number density of independently precipitated (Ti,Nb)(C,N) particles but increased that of γ-Al_(2)O_(3)–Ti N–Cu_(2)S particles.Thus abnormally large PAGs formed in the CGHAZ of the 60Al steel,and they reached a maximum size of 1 mm.These PAGs greatly reduced the microstructural homogeneity and consequently decreased the impact toughness from 134 (0.016wt%Al) to 54 J (0.006wt%Al)at-40℃.
基金jointly supported by the Science Fund for Distinguished Young Scholars of Hunan Province,China(Grant No.2024JJ2073)the National Natural Science Foundation of China(Grant No.52178443)the Fundamental Research Funds for the Central Universities of Central South University,China(Grant No.2022ZZTS0620)。
文摘This study investigated the hydraulic and mechanical behaviors of unsaturated coarse-grained railway embankment fill materials(CREFMs)using a novel unsaturated large-scale triaxial apparatus equipped with the axis translation technique(ATT).Comprehensive soil-water retention and constant-suction triaxial compression tests were conducted to evaluate the effects of initial void ratio,matric suction,and confining pressure on the properties of CREFMs.Key findings reveal a primary suction range of 0 e100 kPa characterized by hysteresis,which intensifies with decreasing density.Notably,the air entry value and residual suction are influenced by void ratio,with higher void ratios leading to decreased air entry values and residual suctions,underscoring the critical role of void ratio in hydraulic behavior.Additionally,the critical state line(CSL)in the bi-logarithmic space of void ratio and mean effective stress shifts towards higher void ratios with increasing matric suction,significantly affecting dilatancy and critical states.Furthermore,the study demonstrated that the mobilized friction angle and modulus properties depend on confining pressure and matric suction.A novel modified dilatancy equation was proposed,which enhances the predictability of CREFMs'responses under variable loading,particularly at high stress ratios defined by the deviatoric stress over the mean effective stress.This research advances the understanding of CREFMs'performance,especially under fluctuating environmental conditions that alter suction levels.
文摘A generic coarse-grained bead-and-spring model,mapped onto comb-shaped polycarboxylate-based(PCE)superplasticizers,is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions.The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution.The effects of ionic strength,side-chain number,and side-chain length on the conformational behavior of PCEs in solution are explored.Single-chain equilibrium properties,including the radius of gyration,end-to-end distance and persistenee length of the polymer backbone,shape-asphericity parameter,and the mean span dimension,are determined.It is found that with the increase of ionic strength,the equilibrium sizes of the polymers decrease only slightly,and a linear dependenew of the persistence length of backbone on the Debye screening length is found,in good agreement with the theory developed by Dobrynin.Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes(radius of gyration and mean span)of the polymer as a whole,but also the persistence length of the backbone due to excluded volume interactions.
基金Funded by the Technology Innovation Leading Program of Shaanxi(No.2022QFY08-02)。
文摘The effects of ultrafine WC(WC_(UF),0.5μm) or W(1μm) and C(0.3μm)(W+C)_(UF) additives on the densification,microstructure and mechanical properties of coarse-grained cemented carbides were compared systematically.Overall,the cemented carbides with WC_(UF)/(W+C)_(UF) additives are almost fully densification to be higher than 99%,and the average grain size is kept above 2.8μm.The WC_(UF) additive assists grains to(truncated)trigonal prism shape by two dimensional(2D) growth,whereas the(W+C)_(UF) additive assists grains to rounded shape by three dimensional(3D) growth,lowers WC contiguity and increases face-centered-cubic Co.The hardness and bending strength of(75WC_(C)-15WC_(UF))-10Co are 86.6 HRA and 2 272 MPa,respectively,both higher than those of(75WC_(C)-15(W+C)_(UF))-10Co,which could be ascribed to the enhanced densification and unblemished grains.However,the fracture toughness of the(75WC_(C)-15(W+C)_(UF))-10Co is 23.5 MPa·m^(1/2),higher than that of the(75WC_(C)-15WC_(UF))-10Co due to the uniform WC-Co structure and flexible binder phase.
基金This work was supported by the National Key Research and Development Program of China(2021YFA1301504)the Chinese Academy of Sciences Strategic Priority Research Program(XDB37040202)the National Natural Science Foundation of China(91953101).
文摘The assembly of a protein complex is very important for its biological function,which can be investigated by determining the order of assembly/disassembly of its protein subunits.Although static structures of many protein com-plexes are available in the protein data bank,their assembly/disassembly orders of subunits are largely unknown.In addition to experimental techniques for studying subcomplexes in the assembly/disassembly of a protein complex,computational methods can be used to predict the assembly/disassembly order.Since sampling is a nontrivial issue in simulating the assembly/disassembly process,coarse-grained simulations are more efficient than atomic simulations are.In this work,we developed computational protocols for predicting the assembly/disassembly orders of protein complexes via coarse-grained simulations.The protocols were illustrated via two protein complexes,and the predicted assembly/disassembly orders were consistent with the available experimental data.
基金financially supported by the Ministry of Science and Technology of the People's Republic of China under Grant No.2012CB215003the National Natural Science Foundation of China under Grant Nos.21176240 and 21406081the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No.XDA07080100
文摘We simulated rapid flow in transient plane Couette flows of granular particles using the smoothed particle hydrodynamics （SPH） solutions of a set of continuum equations, This simulation was performed to test the viability of SPH in solving the equations for the solid phase of the two-fluid model associated with fluidization. We found that SPH requires the handling of fewer particles in simulating the collective behavior of rapid granular flow, thereby bolstering expectations of solving the equations for the solid phase in the two-fluid modeling of fluidization. Further work is needed to investigate the effect of terms describing pressure and viscous stress of solids on stability in simulations.
基金Project supported by the National Institutes of Health of U.S.A.(No.U01HL114476)the National Science Foundation of U.S.A.(Nos.CMMI-1235025 and PHY-1205910)
文摘In this work, the previously developed coarse-grained （CG） particle models for biomembranes and red blood cells （RBCs） are reviewed, and the advantages of the CG particle methods over the continuum and atomistic simulations for modeling biological phenomena are discussed. CG particle models can largely increase the length scale and time scale of atomistic simulations by eliminating the fast degrees of freedom while preserving the mesoscopic structures and properties of the simulated system. Moreover, CG particle models can be used to capture the microstructural alternations in diseased RBCs and simulate the topological changes of biomembranes and RBCs, which are the major challenges to the typical continuum representations of membranes and RBCs. The power and versatility of CG particle methods are demonstrated：through simulating the dynamical processes mvolving significant topological .changes e.g. lipid self-assembly vesicle fusion and membrane budding.
基金Supported by National Natural Science Foundation of China,No.81874390 and No.81573948Shanghai Natural Science Foundation,No.21ZR1464100+1 种基金Science and Technology Innovation Action Plan of Shanghai Science and Technology Commission,No.22S11901700the Shanghai Key Specialty of Traditional Chinese Clinical Medicine,No.shslczdzk01201.
文摘BACKGROUND Rebleeding after recovery from esophagogastric variceal bleeding(EGVB)is a severe complication that is associated with high rates of both incidence and mortality.Despite its clinical importance,recognized prognostic models that can effectively predict esophagogastric variceal rebleeding in patients with liver cirrhosis are lacking.AIM To construct and externally validate a reliable prognostic model for predicting the occurrence of esophagogastric variceal rebleeding.METHODS This study included 477 EGVB patients across 2 cohorts:The derivation cohort(n=322)and the validation cohort(n=155).The primary outcome was rebleeding events within 1 year.The least absolute shrinkage and selection operator was applied for predictor selection,and multivariate Cox regression analysis was used to construct the prognostic model.Internal validation was performed with bootstrap resampling.We assessed the discrimination,calibration and accuracy of the model,and performed patient risk stratification.RESULTS Six predictors,including albumin and aspartate aminotransferase concentrations,white blood cell count,and the presence of ascites,portal vein thrombosis,and bleeding signs,were selected for the rebleeding event prediction following endoscopic treatment(REPET)model.In predicting rebleeding within 1 year,the REPET model ex-hibited a concordance index of 0.775 and a Brier score of 0.143 in the derivation cohort,alongside 0.862 and 0.127 in the validation cohort.Furthermore,the REPET model revealed a significant difference in rebleeding rates(P<0.01)between low-risk patients and intermediate-to high-risk patients in both cohorts.CONCLUSION We constructed and validated a new prognostic model for variceal rebleeding with excellent predictive per-formance,which will improve the clinical management of rebleeding in EGVB patients.
基金the University of Transport Technology under the project entitled“Application of Machine Learning Algorithms in Landslide Susceptibility Mapping in Mountainous Areas”with grant number DTTD2022-16.
文摘This study was aimed to prepare landslide susceptibility maps for the Pithoragarh district in Uttarakhand,India,using advanced ensemble models that combined Radial Basis Function Networks(RBFN)with three ensemble learning techniques:DAGGING(DG),MULTIBOOST(MB),and ADABOOST(AB).This combination resulted in three distinct ensemble models:DG-RBFN,MB-RBFN,and AB-RBFN.Additionally,a traditional weighted method,Information Value(IV),and a benchmark machine learning(ML)model,Multilayer Perceptron Neural Network(MLP),were employed for comparison and validation.The models were developed using ten landslide conditioning factors,which included slope,aspect,elevation,curvature,land cover,geomorphology,overburden depth,lithology,distance to rivers and distance to roads.These factors were instrumental in predicting the output variable,which was the probability of landslide occurrence.Statistical analysis of the models’performance indicated that the DG-RBFN model,with an Area Under ROC Curve(AUC)of 0.931,outperformed the other models.The AB-RBFN model achieved an AUC of 0.929,the MB-RBFN model had an AUC of 0.913,and the MLP model recorded an AUC of 0.926.These results suggest that the advanced ensemble ML model DG-RBFN was more accurate than traditional statistical model,single MLP model,and other ensemble models in preparing trustworthy landslide susceptibility maps,thereby enhancing land use planning and decision-making.
基金in part supported by the National Natural Science Foundation of China(Grant Nos.42288101,42405147 and 42475054)in part by the China National Postdoctoral Program for Innovative Talents(Grant No.BX20230071)。
文摘Conducting predictability studies is essential for tracing the source of forecast errors,which not only leads to the improvement of observation and forecasting systems,but also enhances the understanding of weather and climate phenomena.In the past few decades,dynamical numerical models have been the primary tools for predictability studies,achieving significant progress.Nowadays,with the advances in artificial intelligence(AI)techniques and accumulations of vast meteorological data,modeling weather and climate events using modern data-driven approaches is becoming trendy,where FourCastNet,Pangu-Weather,and GraphCast are successful pioneers.In this perspective article,we suggest AI models should not be limited to forecasting but be expanded to predictability studies,leveraging AI's advantages of high efficiency and self-contained optimization modules.To this end,we first remark that AI models should possess high simulation capability with fine spatiotemporal resolution for two kinds of predictability studies.AI models with high simulation capabilities comparable to numerical models can be considered to provide solutions to partial differential equations in a data-driven way.Then,we highlight several specific predictability issues with well-determined nonlinear optimization formulizations,which can be well-studied using AI models,holding significant scientific value.In addition,we advocate for the incorporation of AI models into the synergistic cycle of the cognition–observation–model paradigm.Comprehensive predictability studies have the potential to transform“big data”to“big and better data”and shift the focus from“AI for forecasts”to“AI for science”,ultimately advancing the development of the atmospheric and oceanic sciences.
基金Under the auspices of National Natural Science Foundation of China(No.42330510)。
文摘With the development of smart cities and smart technologies,parks,as functional units of the city,are facing smart transformation.The development of smart parks can help address challenges of technology integration within urban spaces and serve as testbeds for exploring smart city planning and governance models.Information models facilitate the effective integration of technology into space.Building Information Modeling(BIM)and City Information Modeling(CIM)have been widely used in urban construction.However,the existing information models have limitations in the application of the park,so it is necessary to develop an information model suitable for the park.This paper first traces the evolution of park smart transformation,reviews the global landscape of smart park development,and identifies key trends and persistent challenges.Addressing the particularities of parks,the concept of Park Information Modeling(PIM)is proposed.PIM leverages smart technologies such as artificial intelligence,digital twins,and collaborative sensing to help form a‘space-technology-system’smart structure,enabling systematic management of diverse park spaces,addressing the deficiency in park-level information models,and aiming to achieve scale articulation between BIM and CIM.Finally,through a detailed top-level design application case study of the Nanjing Smart Education Park in China,this paper illustrates the translation process of the PIM concept into practice,showcasing its potential to provide smart management tools for park managers and enhance services for park stakeholders,although further empirical validation is required.
基金supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX24_0714).
文摘To examine the similarities and differences in the evolution of cavity,wetting and dynamics of a highspeed,oblique water-entry projectile with different positive angles of attack,a comparative analysis has been conducted based on the numerical results of two mathematical models,the rigid-body model and fluid-structure interaction model.In addition,the applicable scope of the above two methods,and the structural response characteristics of the projectile have also been investigated.Our results demonstrate that:(1) The impact loads and angular motion of the projectile of the rigid-body method are more likely to exhibit periodic variations due to the periodic tail slap,its range of positive angles of attack is about α<2°.(2) When the projectile undergone significant wetting,a strong coupling effect is observed among wetting,structural deformation,and projectile motion.With the applied projectile shape,it is observed that,when the projectile bends,the final wetting position is that of Part B(cylinder of body).With the occu rrence of this phenomenon,the projectile ballistics beco me completely unstable.(3) The force exerted on the lower surface of the projectile induced by wetting is the primary reason of the destabilization of the projectile traj ectory and structu ral deformation failure.Bending deformation is most likely to appear at the junction of Part C(cone of body) and Part D(tail).The safe angles of attack of the projectile stability are found to be about α≤2°.
