Elevation change monitoring of the Antarctic ice sheet has been a key issue in global change research.Satellite altimetry has been proven to be effective in detecting ice sheet variations. With the development of ICES...Elevation change monitoring of the Antarctic ice sheet has been a key issue in global change research.Satellite altimetry has been proven to be effective in detecting ice sheet variations. With the development of ICESat-2, many elevation observations can be used to derive elevation changes. However, the large amount of multitemporal data may include anomalous data points, increasing the uncertainty of the results. In this work, we improved the traditional repeat track method by introducing the Institute of Geodesy and Geophysics Ⅲ(IGGⅢ) method to obtain high-accuracy estimates of elevation change. The improved method was applied to analyze elevation changes along the transect from Zhongshan Station to Dome A in East Antarctica via ICESat-2 satellite altimetry data. The results show that the improved and traditional methods yield consistent numerical and spatial elevation change distributions. The elevation change calculated via the traditional method is 0.033 ± 0.131 m/yr, whereas the elevation change estimated via the IGGⅢ robust estimation method is 0.033 ± 0.109 m/yr from March 2019 to December 2021.In terms of spatial distribution, elevation changes in inland areas remain close to equilibrium, whereas regions with steeper ice sheet margins exhibit positive accumulation trends in elevation changes. The improved method reduces the standard error of the adjustment function from 0.975 to 0.691 m/yr. The improvement is particularly remarkable in the area between 72°S and 77°S. The results demonstrate that the IGGⅢ method effectively reduces errors caused by the inclusion of anomalous data and maintains the high data utilization rate of repeat-orbit methods.展开更多
Based on the fact that 3-D model discretization by artificial could not always be successfully implemented especially for large-scaled problems when high accuracy and efficiency were required, a new adaptive multigrid...Based on the fact that 3-D model discretization by artificial could not always be successfully implemented especially for large-scaled problems when high accuracy and efficiency were required, a new adaptive multigrid finite element method was proposed. In this algorithm, a-posteriori error estimator was employed to generate adaptively refined mesh on a given initial mesh. On these iterative meshes, V-cycle based multigrid method was adopted to fast solve each linear equation with each initial iterative term interpolated from last mesh. With this error estimator, the unknowns were nearly optimally distributed on the final mesh which guaranteed the accuracy. The numerical results show that the multigrid solver is faster and more stable compared with ICCG solver. Meanwhile, the numerical results obtained from the final model discretization approximate the analytical solutions with maximal relative errors less than 1%, which remarkably validates this algorithm.展开更多
Black phosphorus(BP),as one of the most promising fillers for flame retarding polymer,has been seriously limited in practical application,due to the agglomeration and poor structural stability challenges.Here,the BP w...Black phosphorus(BP),as one of the most promising fillers for flame retarding polymer,has been seriously limited in practical application,due to the agglomeration and poor structural stability challenges.Here,the BP was modified by MXene and polydopamine(PDA)via ultrasonication and dopamine modification strategy to improve the structural stability and dispersibility in the matrix.Then,the obtained(BP-MXene@PDA)nanohybrid was employed to promote the mechanical performance,thermal stability,and flame retardancy of thermoplastic polyurethane elastomer(TPU).The resultant TPU composite containing 2 wt.%of BP1-MXene2@PDA showed a 19.2%improvement in the tensile strength and a 13.8%increase in the elongation at break compared to those of the pure TPU.The thermogravimetric analysis suggested that BP-MXene@PDA clearly enhances the thermal stability of TPU composites.Furthermore,the introduction of the BP-MXene@PDA nanohybrids could considerably improve the flame retardancy of TPU composite,i.e.,64.2%and 27.3%decrease in peak heat release rate and total heat release,respectively.The flame-retardant mechanisms of TPU/BP-MXene@PDA in the gas phase and condensed phase were investigated systematically.This work provides a novel strategy to simultaneously enhance the fire safety and mechanical properties of TPU,thus expanding its industrial applications.展开更多
In this study,we present a novel nodal integration-based particle finite element method(N-PFEM)designed for the dynamic analysis of saturated soils.Our approach incorporates the nodal integration technique into a gene...In this study,we present a novel nodal integration-based particle finite element method(N-PFEM)designed for the dynamic analysis of saturated soils.Our approach incorporates the nodal integration technique into a generalised Hellinger-Reissner(HR)variational principle,creating an implicit PFEM formulation.To mitigate the volumetric locking issue in low-order elements,we employ a node-based strain smoothing technique.By discretising field variables at the centre of smoothing cells,we achieve nodal integration over cells,eliminating the need for sophisticated mapping operations after re-meshing in the PFEM.We express the discretised governing equations as a min-max optimisation problem,which is further reformulated as a standard second-order cone programming(SOCP)problem.Stresses,pore water pressure,and displacements are simultaneously determined using the advanced primal-dual interior point method.Consequently,our numerical model offers improved accuracy for stresses and pore water pressure compared to the displacement-based PFEM formulation.Numerical experiments demonstrate that the N-PFEM efficiently captures both transient and long-term hydro-mechanical behaviour of saturated soils with high accuracy,obviating the need for stabilisation or regularisation techniques commonly employed in other nodal integration-based PFEM approaches.This work holds significant implications for the development of robust and accurate numerical tools for studying saturated soil dynamics.展开更多
This paper introduces a new methodology to measure the elastic constants of transversely isotropic rocks from a single uniaxial compression test.We first give the mathematical proof that a uniaxial compression test pr...This paper introduces a new methodology to measure the elastic constants of transversely isotropic rocks from a single uniaxial compression test.We first give the mathematical proof that a uniaxial compression test provides only four independent strain equations.As a result,the exact determination of all five independent elastic constants from only one test is not possible.An approximate determination of the Young’s moduli and the Poisson’s ratios is however practical and efficient when adding the Saint-Venant relation as the fifth equation.Explicit formulae are then developed to calculate both secant and tangent definitions of the five elastic constants from a minimum of four strain measurements.The results of this new methodology applied on three granitic samples demonstrate a significant stress-induced nonlinear behavior,where the tangent moduli increase by a factor of three to four when the rock is loaded up to 20 MPa.The static elastic constants obtained from the uniaxial compression test are also found to be significantly smaller than the dynamic ones obtained from the ultrasonic measurements.展开更多
Carious lesions are bacteria-caused destructions of the mineralised dental tissues,marked by the simultaneous activation of immune responses and regenerative events within the soft dental pulp tissue.While major molec...Carious lesions are bacteria-caused destructions of the mineralised dental tissues,marked by the simultaneous activation of immune responses and regenerative events within the soft dental pulp tissue.While major molecular players in tooth decay have been uncovered during the past years,a detailed map of the molecular and cellular landscape of the diseased pulp is still missing.In this study we used single-cell RNA sequencing analysis,supplemented with immunostaining,to generate a comprehensive single-cell atlas of the pulp of carious human teeth.Our data demonstrated modifications in the various cell clusters within the pulp of carious teeth,such as immune cells,mesenchymal stem cells(MSC)and fibroblasts,when compared to the pulp of healthy human teeth.Active immune response in the carious pulp tissue is accompanied by specific changes in the fibroblast and MSC clusters.These changes include the upregulation of genes encoding extracellular matrix(ECM)components,including COL1A1 and Fibronectin(FN1),and the enrichment of the fibroblast cluster with myofibroblasts.The incremental changes in the ECM composition of carious pulp tissues were further confirmed by immunostaining analyses.Assessment of the Fibronectin fibres under mechanical strain conditions showed a significant tension reduction in carious pulp tissues,compared to the healthy ones.The present data demonstrate molecular,cellular and biomechanical alterations in the pulp of human carious teeth,indicative of extensive ECM remodelling,reminiscent of fibrosis observed in other organs.This comprehensive atlas of carious human teeth can facilitate future studies of dental pathologies and enable comparative analyses across diseased organs.展开更多
This paper focuses on land resource consumption due to urban sprawl. Special attention is given to shrinking regions, characterized by economic decline, demographic change, and high unemployment rates. In these region...This paper focuses on land resource consumption due to urban sprawl. Special attention is given to shrinking regions, characterized by economic decline, demographic change, and high unemployment rates. In these regions, vast terrain is abandoned and falls derelict. A geographic information system （GIS） based multi-criteria decision tool is introduced to determine the reuse potential of derelict terrain, to investigate the possible reuse options （housing, business and trade, industry, services, tourism and leisure, and re-greening）, and to visualize the best reuse options for groups of sites on a regional scale. Achievement functions for attribute data are presented to assess the best reuse options based on a multi-attribute technique. The assessment tool developed is applied to a model region in Germany. The application of the assessment tool enables communities to become aware of their resources of derelict land and their reuse potential.展开更多
When the existing information does not contain all categories,the Generalized Evidence Theory(GET)can deal with information fusion.However,the question of how to determine the number of categories through GET is still...When the existing information does not contain all categories,the Generalized Evidence Theory(GET)can deal with information fusion.However,the question of how to determine the number of categories through GET is still intriguing.To address this question,a modified k-means clustering,named centers initialized clustering is proposed,filling the gap of identification and complement of the frame of discernment.Based on this clustering method,the number of cat-egories is determined.The initialized centers selected by center density keep the cluster results con-stant,enhancing the stability of clustering results.Besides,constructing Generalized basic Probability Assignment(GBPA)modules in a conservative way improves the reliability of the results.The mass of empty set in combined GBPAs is the indicator of the number of categories.Experiments on real and artificial data sets are conducted to show the effectiveness.展开更多
Background Dietary supplements based on tannin extracts or essential oil compounds(EOC)have been repeatedly reported as a promising feeding strategy to reduce the environmental impact of ruminant husbandry.A previous ...Background Dietary supplements based on tannin extracts or essential oil compounds(EOC)have been repeatedly reported as a promising feeding strategy to reduce the environmental impact of ruminant husbandry.A previous batch culture screening of various supplements identified selected mixtures with an enhanced potential to mitigate ruminal methane and ammonia formation.Among these,Q-2(named after quebracho extract and EOC blend 2,composed of carvacrol,thymol,and eugenol)and C-10(chestnut extract and EOC blend 10,consisting of oregano and thyme essential oils and limonene)have been investigated in detail in the present study with the semi-continuous rumen simulation technique(Rusitec)in three independent runs.For this purpose,Q-2 and C-10,dosed according to the previous study,were compared with a non-supplemented diet(negative control,NC)and with one supplemented with the commercial EOC-based Agolin^(R) Ruminant(positive control,PC).Results From d 5 to 10 of fermentation incubation liquid was collected and analysed for pH,ammonia,protozoa count,and gas composition.Feed residues were collected for the determination of ruminal degradability.On d 10,samples of incubation liquid were also characterised for bacterial,archaeal and fungal communities by high-throughput sequencing of 16S rRNA and 26S ribosomal large subunit gene amplicons.Regardless of the duration of the fermentation period,Q-2 and C-10 were similarly efficient as PC in mitigating either ammonia(-37%by Q-2,-34%by PC)or methane formation(-12%by C-10,-12%by PC).The PC was also responsible for lower feed degradability and bacterial and fungal richness,whereas Q-2 and C-10 effects,particularly on microbiome diversities,were limited compared to NC.Conclusions All additives showed the potential to mitigate methane or ammonia formation,or both,in vitro over a period of 10 d.However,several differences occurred between PC and Q-2/C-10,indicating different mechanisms of action.The pronounced defaunation caused by PC and its suggested consequences apparently determined at least part of the mitigant effects.Although the depressive effect on NDF degradability caused by Q-2 and C-10 might partially explain their mitigation properties,their mechanisms of action remain mostly to be elucidated.展开更多
Polyolefins that bear a chiral side chain(typically an isobutyl group)experience a so-called macromolecularamplification of chirality:the chiral side-chain induces a slight preference for either tg or tg(?) main chain...Polyolefins that bear a chiral side chain(typically an isobutyl group)experience a so-called macromolecularamplification of chirality:the chiral side-chain induces a slight preference for either tg or tg(?) main chain conformation.Thisslight conformational bias is amplified cooperatively along the chain,and results in preferred chirality of the main chainhelical conformations.As a result,these polymers display a liquid-crystal(LC)phase both in solution and,in the melt as atransient phase on the way to crystallization.The existence of two processes(melt-LC and LC-crystal transitions)results inunconventional behaviors that were first analyzed by Pino and collaborators back in 1975.These polymers also offer a meansto test the structural consequences of recently introduced crystallization schemes.These schemes postulate the formation of atransient liquid-crystal phase as a general scheme for polymer crystallization.展开更多
We propose a parallel stochastic Newton method （PSN） for minimizing unconstrained smooth convex functions. We analyze the method in the strongly convex case, and give conditions under which acceleration can be expec...We propose a parallel stochastic Newton method （PSN） for minimizing unconstrained smooth convex functions. We analyze the method in the strongly convex case, and give conditions under which acceleration can be expected when compared to its serial counterpart. We show how PSN can be applied to the large quadratic function minimization in general, and empirical risk minimization problems. We demonstrate the practical efficiency of the method through numerical experiments and models of simple matrix classes.展开更多
We evaluated bismuth doped cerium oxide catalysts for the continuous synthesis of dimethyl carbonate(DMC)from methanol and carbon dioxide in the absence of a dehydrating agent.Bi_(x)Ce_(1-x)O_(δ)nanocomposites of var...We evaluated bismuth doped cerium oxide catalysts for the continuous synthesis of dimethyl carbonate(DMC)from methanol and carbon dioxide in the absence of a dehydrating agent.Bi_(x)Ce_(1-x)O_(δ)nanocomposites of various compositions(x=0.06-0.24)were coated on a ceramic honeycomb and their structural and catalytic properties were examined.The incorporation of Bi species into the CeO_(2) lattice facilitated controlling of the surface population of oxygen vacancies,which is shown to play a crucial role in the mechanism of this reaction and is an important parameter for the design of ceria-based catalysts.The DMC production rate of the Bi_(x)Ce_(1-x)O_(δ) catalysts was found to be strongly enhanced with increasing Ov concentration.The concentration of oxygen vacancies exhibited a maximum for Bi_(0.12)Ce_(0.88)O_(δ),which afforded the highest DMC production rate.Long-term tests showed stable activity and selectivity of this catalyst over 45 h on-stream at 140°C and a gas-hourly space velocity of 2,880 mL·g_(cat)^(-1)·h^(-1).In-situ modulation excitation diffuse reflection Fourier transform infrared spectroscopy and first-principle calculations indicate that the DMC synthesis occurs through reaction of a bidentate carbonate intermediate with the activated methoxy(-OCH_(3))species.The activation of C0_(2) to form the bidentate carbonate intermediate on the oxygen vacancy sites is identified as highest energy barrier in the reaction pathway and thus is likely the rate-determining step.展开更多
Design and exploitation of flame retardant polymers with high electrical conductivity are desired for polymer applications in electronics.Herein,a novel phosphorus-nitrogen intumescent flame retardant was synthesized ...Design and exploitation of flame retardant polymers with high electrical conductivity are desired for polymer applications in electronics.Herein,a novel phosphorus-nitrogen intumescent flame retardant was synthesized from pentaerythritol octahydrogen tetraphosphate,phenylphosphonyl dichloride,and aniline.Low-density polyethylene was combined with the flame retardant and multi-walled carbon nanotubes to form a nanocomposite material via a ball-milling and hot-pressing method.The electrical conductivity,mechanical properties,thermal performance,and flame retardancy of the composites were investigated using a four-point probe instrument,universal tensile machine,thermogravimetric analysis,and cone calorimeter tests,respectively.It was found that the addition of multi-walled carbon nanotubes can significantly improve the electrical conductivity and mechanical properties of the low-density polyethylene composites.Furthermore,the combination of multi-walled carbon nanotubes and phosphorus–nitrogen flame retardant remarkably enhances the flame retardancy of matrixes with an observed decrease of the peak heat release rate and total heat release of 49.8%and 51.9%,respectively.This study provides a new and effective methodology to substantially enhance the electrical conductivity and flame retardancy of polymers with an attractive prospect for polymer applications in electrical equipment.展开更多
The waste of resources associated with fruit decay is rapidly spreading globally,threatening the interests of relevant practitioners and the health of consumer groups,and demanding precise solutions.Controlling fruit ...The waste of resources associated with fruit decay is rapidly spreading globally,threatening the interests of relevant practitioners and the health of consumer groups,and demanding precise solutions.Controlling fruit ripening through ethylene reg-ulation is one of the most important strategies for providing high-quality fruits.However,current materials for ethylene regulation still have difficulty realizing their application potential due to high manufacturing costs and performance defi-ciencies.In this review,the ethylene-controlled release materials for ripening based on molecular encapsulation and the ethylene scavengers for preservation based on mechanisms such as oxidation,photodegradation,and adsorption are presented.We discuss and analyze a wide range of materials in terms of mechanism,perfor-mance,potential of applicability,and sustainability.The ethylene release behavior of encapsulating materials depends on the form in which the ethylene binds to the material as well as on environmental factors(humidity and temperature).For ethy-lene scavengers,there are a variety of scavenging mechanisms,but they generally require porous materials as adsorption carriers.We highlight the great opportunity of designing soft crystalline porous materials as efficient ethylene adsorbent due to their unique structural properties.We present this review,including a summary of practical characteristics and deficiencies of various materials,to establish a system-atic understanding of fruit quality assurance materials applied to ethylene regulation,anticipating a promising prospect for these new materials.展开更多
The form of a building is among the most critical design aspects concerning building energy consumption.Form-based passive design strategies,like solar control,can significantly reduce heating and cooling demands if i...The form of a building is among the most critical design aspects concerning building energy consumption.Form-based passive design strategies,like solar control,can significantly reduce heating and cooling demands if implemented early in the design process.In this sense,there is an evident need for tools that can adequately support designers in their decisions.This paper aims to illustrate how geometry-based graphical methods(GGM)can provide effective support in the conceptual design stage.The paper introduces a novel digital framework for designing and analysing shading devices that leverages geometrical models and graphical methods.The digital implementation of GGM allows extending their applicability to threedimensional and non-planar geometries.A comprehensive review of existing methods and tools for the design of shading devices lays the ground for the proposed digital framework,which is then demonstrated through two case studies.The results show that the diagrammatic nature of GGM facilitates a better and more direct understanding of the relationship between form and performance.展开更多
This paper opens a series of papers aimed at finalizing the development of the lattice Boltzmann method for complex hydrodynamic systems.The lattice Boltzmann method is introduced at the elementary level of the linear...This paper opens a series of papers aimed at finalizing the development of the lattice Boltzmann method for complex hydrodynamic systems.The lattice Boltzmann method is introduced at the elementary level of the linear advection equation.Details are provided on lifting the target macroscopic equations to a kinetic equation,and,after that,to the fully discrete lattice Boltzmann scheme.The over-relaxation method is put forward as a cornerstone of the second-order temporal discretization,and its enhancement with the use of the entropy estimate is explained in detail.A new asymptotic expansion of the entropy estimate is derived,and implemented in the sample code.It is shown that the lattice Boltzmann method provides a computationally efficient way of numerically solving the advection equation with a controlled amount of numerical dissipation,while retaining positivity.展开更多
Parkinson's disease(PD)is the second most common neurodegenerative disorder.The clinical manifestations of PD include motor symptoms,such as bradykinesia,resting tremor,rigidity,and nonmotor symptoms,which include...Parkinson's disease(PD)is the second most common neurodegenerative disorder.The clinical manifestations of PD include motor symptoms,such as bradykinesia,resting tremor,rigidity,and nonmotor symptoms,which include disturbances in sleep,gastrointestinal function,and olfaction.PD misdiagnosis rates have been reported to reach approximately 30%,partly owing to the heterogeneity of parkinsonism with non-PD pathologies,and the differential diagnosis of PD from neurodegenerative diseases such as multiple systemic atrophy(MSA)and progressive supranuclear palsy poses another unmet need.展开更多
Alzheimer’s disease(AD)is the most common cause of dementia,characterized by progressive cognitive decline,and affects over 55 million people worldwide.AD is pathological featured by the aberrant accumulation of amyl...Alzheimer’s disease(AD)is the most common cause of dementia,characterized by progressive cognitive decline,and affects over 55 million people worldwide.AD is pathological featured by the aberrant accumulation of amyloid-βplaques,neurofibrillary tangles formed by hyperphosphorylated tau,synaptic loss,and dysfunction of neurotransmitter systems.Evidence from in vivo and autopsy studies has consistently shown that synaptic dysfunction and loss are strongly correlated with cognitive decline in AD,particularly in brain regions such as the hippocampus and cortex,which are critical for memory formation and processing.This perspective highlights recent histopathological findings related to synaptic dysfunction in AD,advancements in the development of imaging and fluid-based biomarkers for synaptic loss,and future studies.展开更多
We present a fast Galerkin spectral method to solve logarithmic singular equations on segments. The proposed method uses weighted first-kind Chebyshev polynomials. Conver- gence rates of several orders are obtained fo...We present a fast Galerkin spectral method to solve logarithmic singular equations on segments. The proposed method uses weighted first-kind Chebyshev polynomials. Conver- gence rates of several orders are obtained for fractional Sobolev spaces H^-1/2 （or H00^-l/2）. Main tools are the approximation properties of the discretization basis, the construction of a suitable Hilbert scale for weighted L2-spaces and local regularity estimates. Numerical experiments are provided to validate our claims,展开更多
Realization of the Shan-Chen multiphase flow lattice Boltzmann model is considered in the framework of the higher-order Galilean invariant lattices.The present multiphase lattice Boltzmann model is used in two-dimensi...Realization of the Shan-Chen multiphase flow lattice Boltzmann model is considered in the framework of the higher-order Galilean invariant lattices.The present multiphase lattice Boltzmann model is used in two-dimensional simulation of droplet collisions at high Weber numbers.Results are found to be in a good agreement with experimental findings.展开更多
基金supported by the National Key Research and Development Program of China under grant number 2023YFC2809103the Fundamental Research Funds for the Central Universities under grant numbers 2042022kf1204, 2042022kf1069, 2042023gf0012, 2042022dx0001+1 种基金the Hubei Provincial Natural Science Foundation of China under grant number 2022CFB081the State Key Laboratory of Geodesy and Earth's Dynamics, Innovation Academy for Precision Measurement Science and Technology under grant number SKLGED2023-2-6
文摘Elevation change monitoring of the Antarctic ice sheet has been a key issue in global change research.Satellite altimetry has been proven to be effective in detecting ice sheet variations. With the development of ICESat-2, many elevation observations can be used to derive elevation changes. However, the large amount of multitemporal data may include anomalous data points, increasing the uncertainty of the results. In this work, we improved the traditional repeat track method by introducing the Institute of Geodesy and Geophysics Ⅲ(IGGⅢ) method to obtain high-accuracy estimates of elevation change. The improved method was applied to analyze elevation changes along the transect from Zhongshan Station to Dome A in East Antarctica via ICESat-2 satellite altimetry data. The results show that the improved and traditional methods yield consistent numerical and spatial elevation change distributions. The elevation change calculated via the traditional method is 0.033 ± 0.131 m/yr, whereas the elevation change estimated via the IGGⅢ robust estimation method is 0.033 ± 0.109 m/yr from March 2019 to December 2021.In terms of spatial distribution, elevation changes in inland areas remain close to equilibrium, whereas regions with steeper ice sheet margins exhibit positive accumulation trends in elevation changes. The improved method reduces the standard error of the adjustment function from 0.975 to 0.691 m/yr. The improvement is particularly remarkable in the area between 72°S and 77°S. The results demonstrate that the IGGⅢ method effectively reduces errors caused by the inclusion of anomalous data and maintains the high data utilization rate of repeat-orbit methods.
基金Projects(2006AA06Z105, 2007AA06Z134) supported by the National High-Tech Research and Development Program of ChinaProjects(2007, 2008) supported by China Scholarship Council (CSC)
文摘Based on the fact that 3-D model discretization by artificial could not always be successfully implemented especially for large-scaled problems when high accuracy and efficiency were required, a new adaptive multigrid finite element method was proposed. In this algorithm, a-posteriori error estimator was employed to generate adaptively refined mesh on a given initial mesh. On these iterative meshes, V-cycle based multigrid method was adopted to fast solve each linear equation with each initial iterative term interpolated from last mesh. With this error estimator, the unknowns were nearly optimally distributed on the final mesh which guaranteed the accuracy. The numerical results show that the multigrid solver is faster and more stable compared with ICCG solver. Meanwhile, the numerical results obtained from the final model discretization approximate the analytical solutions with maximal relative errors less than 1%, which remarkably validates this algorithm.
基金supported by the National Natural Science Foundation of China(No.21908031)Scientific Research Funds of Yunnan Education Department(No.2021Y111)。
文摘Black phosphorus(BP),as one of the most promising fillers for flame retarding polymer,has been seriously limited in practical application,due to the agglomeration and poor structural stability challenges.Here,the BP was modified by MXene and polydopamine(PDA)via ultrasonication and dopamine modification strategy to improve the structural stability and dispersibility in the matrix.Then,the obtained(BP-MXene@PDA)nanohybrid was employed to promote the mechanical performance,thermal stability,and flame retardancy of thermoplastic polyurethane elastomer(TPU).The resultant TPU composite containing 2 wt.%of BP1-MXene2@PDA showed a 19.2%improvement in the tensile strength and a 13.8%increase in the elongation at break compared to those of the pure TPU.The thermogravimetric analysis suggested that BP-MXene@PDA clearly enhances the thermal stability of TPU composites.Furthermore,the introduction of the BP-MXene@PDA nanohybrids could considerably improve the flame retardancy of TPU composite,i.e.,64.2%and 27.3%decrease in peak heat release rate and total heat release,respectively.The flame-retardant mechanisms of TPU/BP-MXene@PDA in the gas phase and condensed phase were investigated systematically.This work provides a novel strategy to simultaneously enhance the fire safety and mechanical properties of TPU,thus expanding its industrial applications.
基金supported by the Swiss National Science Foundation(Grant No.189882)the National Natural Science Foundation of China(Grant No.41961134032)support provided by the New Investigator Award grant from the UK Engineering and Physical Sciences Research Council(Grant No.EP/V012169/1).
文摘In this study,we present a novel nodal integration-based particle finite element method(N-PFEM)designed for the dynamic analysis of saturated soils.Our approach incorporates the nodal integration technique into a generalised Hellinger-Reissner(HR)variational principle,creating an implicit PFEM formulation.To mitigate the volumetric locking issue in low-order elements,we employ a node-based strain smoothing technique.By discretising field variables at the centre of smoothing cells,we achieve nodal integration over cells,eliminating the need for sophisticated mapping operations after re-meshing in the PFEM.We express the discretised governing equations as a min-max optimisation problem,which is further reformulated as a standard second-order cone programming(SOCP)problem.Stresses,pore water pressure,and displacements are simultaneously determined using the advanced primal-dual interior point method.Consequently,our numerical model offers improved accuracy for stresses and pore water pressure compared to the displacement-based PFEM formulation.Numerical experiments demonstrate that the N-PFEM efficiently captures both transient and long-term hydro-mechanical behaviour of saturated soils with high accuracy,obviating the need for stabilisation or regularisation techniques commonly employed in other nodal integration-based PFEM approaches.This work holds significant implications for the development of robust and accurate numerical tools for studying saturated soil dynamics.
基金financially supported by the Swiss Innovation Agency Innosuisseispart of the Swiss Competence Center for Energy Research-Supply of Electricity (SCCER-SoE)+1 种基金the Werner Siemens FoundationETH Zurich for their financial support
文摘This paper introduces a new methodology to measure the elastic constants of transversely isotropic rocks from a single uniaxial compression test.We first give the mathematical proof that a uniaxial compression test provides only four independent strain equations.As a result,the exact determination of all five independent elastic constants from only one test is not possible.An approximate determination of the Young’s moduli and the Poisson’s ratios is however practical and efficient when adding the Saint-Venant relation as the fifth equation.Explicit formulae are then developed to calculate both secant and tangent definitions of the five elastic constants from a minimum of four strain measurements.The results of this new methodology applied on three granitic samples demonstrate a significant stress-induced nonlinear behavior,where the tangent moduli increase by a factor of three to four when the rock is loaded up to 20 MPa.The static elastic constants obtained from the uniaxial compression test are also found to be significantly smaller than the dynamic ones obtained from the ultrasonic measurements.
文摘Carious lesions are bacteria-caused destructions of the mineralised dental tissues,marked by the simultaneous activation of immune responses and regenerative events within the soft dental pulp tissue.While major molecular players in tooth decay have been uncovered during the past years,a detailed map of the molecular and cellular landscape of the diseased pulp is still missing.In this study we used single-cell RNA sequencing analysis,supplemented with immunostaining,to generate a comprehensive single-cell atlas of the pulp of carious human teeth.Our data demonstrated modifications in the various cell clusters within the pulp of carious teeth,such as immune cells,mesenchymal stem cells(MSC)and fibroblasts,when compared to the pulp of healthy human teeth.Active immune response in the carious pulp tissue is accompanied by specific changes in the fibroblast and MSC clusters.These changes include the upregulation of genes encoding extracellular matrix(ECM)components,including COL1A1 and Fibronectin(FN1),and the enrichment of the fibroblast cluster with myofibroblasts.The incremental changes in the ECM composition of carious pulp tissues were further confirmed by immunostaining analyses.Assessment of the Fibronectin fibres under mechanical strain conditions showed a significant tension reduction in carious pulp tissues,compared to the healthy ones.The present data demonstrate molecular,cellular and biomechanical alterations in the pulp of human carious teeth,indicative of extensive ECM remodelling,reminiscent of fibrosis observed in other organs.This comprehensive atlas of carious human teeth can facilitate future studies of dental pathologies and enable comparative analyses across diseased organs.
基金supported by the German Federal Ministry of Education and Research (BMBF Berlin)the Federal Office of Building and Regional Planning (BBR Bonn)the State of Thuringia and the State Development Corporation (LEG) Thuringia
文摘This paper focuses on land resource consumption due to urban sprawl. Special attention is given to shrinking regions, characterized by economic decline, demographic change, and high unemployment rates. In these regions, vast terrain is abandoned and falls derelict. A geographic information system （GIS） based multi-criteria decision tool is introduced to determine the reuse potential of derelict terrain, to investigate the possible reuse options （housing, business and trade, industry, services, tourism and leisure, and re-greening）, and to visualize the best reuse options for groups of sites on a regional scale. Achievement functions for attribute data are presented to assess the best reuse options based on a multi-attribute technique. The assessment tool developed is applied to a model region in Germany. The application of the assessment tool enables communities to become aware of their resources of derelict land and their reuse potential.
基金supported by the National Natural Science Foundation of China(No.61973332)the JSPS Invitational Fellowships for Research in Japan(Short-term).
文摘When the existing information does not contain all categories,the Generalized Evidence Theory(GET)can deal with information fusion.However,the question of how to determine the number of categories through GET is still intriguing.To address this question,a modified k-means clustering,named centers initialized clustering is proposed,filling the gap of identification and complement of the frame of discernment.Based on this clustering method,the number of cat-egories is determined.The initialized centers selected by center density keep the cluster results con-stant,enhancing the stability of clustering results.Besides,constructing Generalized basic Probability Assignment(GBPA)modules in a conservative way improves the reliability of the results.The mass of empty set in combined GBPAs is the indicator of the number of categories.Experiments on real and artificial data sets are conducted to show the effectiveness.
基金partially funded with Ferrero 3P projectsupported by the European Union under the European Regional Development Fund(part of the Union’s response to the COVID-19 outbreak,AXIS VI—Investment Priority 13i—Action 3.1.1)。
文摘Background Dietary supplements based on tannin extracts or essential oil compounds(EOC)have been repeatedly reported as a promising feeding strategy to reduce the environmental impact of ruminant husbandry.A previous batch culture screening of various supplements identified selected mixtures with an enhanced potential to mitigate ruminal methane and ammonia formation.Among these,Q-2(named after quebracho extract and EOC blend 2,composed of carvacrol,thymol,and eugenol)and C-10(chestnut extract and EOC blend 10,consisting of oregano and thyme essential oils and limonene)have been investigated in detail in the present study with the semi-continuous rumen simulation technique(Rusitec)in three independent runs.For this purpose,Q-2 and C-10,dosed according to the previous study,were compared with a non-supplemented diet(negative control,NC)and with one supplemented with the commercial EOC-based Agolin^(R) Ruminant(positive control,PC).Results From d 5 to 10 of fermentation incubation liquid was collected and analysed for pH,ammonia,protozoa count,and gas composition.Feed residues were collected for the determination of ruminal degradability.On d 10,samples of incubation liquid were also characterised for bacterial,archaeal and fungal communities by high-throughput sequencing of 16S rRNA and 26S ribosomal large subunit gene amplicons.Regardless of the duration of the fermentation period,Q-2 and C-10 were similarly efficient as PC in mitigating either ammonia(-37%by Q-2,-34%by PC)or methane formation(-12%by C-10,-12%by PC).The PC was also responsible for lower feed degradability and bacterial and fungal richness,whereas Q-2 and C-10 effects,particularly on microbiome diversities,were limited compared to NC.Conclusions All additives showed the potential to mitigate methane or ammonia formation,or both,in vitro over a period of 10 d.However,several differences occurred between PC and Q-2/C-10,indicating different mechanisms of action.The pronounced defaunation caused by PC and its suggested consequences apparently determined at least part of the mitigant effects.Although the depressive effect on NDF degradability caused by Q-2 and C-10 might partially explain their mitigation properties,their mechanisms of action remain mostly to be elucidated.
文摘Polyolefins that bear a chiral side chain(typically an isobutyl group)experience a so-called macromolecularamplification of chirality:the chiral side-chain induces a slight preference for either tg or tg(?) main chain conformation.Thisslight conformational bias is amplified cooperatively along the chain,and results in preferred chirality of the main chainhelical conformations.As a result,these polymers display a liquid-crystal(LC)phase both in solution and,in the melt as atransient phase on the way to crystallization.The existence of two processes(melt-LC and LC-crystal transitions)results inunconventional behaviors that were first analyzed by Pino and collaborators back in 1975.These polymers also offer a meansto test the structural consequences of recently introduced crystallization schemes.These schemes postulate the formation of atransient liquid-crystal phase as a general scheme for polymer crystallization.
文摘We propose a parallel stochastic Newton method （PSN） for minimizing unconstrained smooth convex functions. We analyze the method in the strongly convex case, and give conditions under which acceleration can be expected when compared to its serial counterpart. We show how PSN can be applied to the large quadratic function minimization in general, and empirical risk minimization problems. We demonstrate the practical efficiency of the method through numerical experiments and models of simple matrix classes.
基金supported by the National Natural Science Foundation of China(Nos.21773189 and 11974195)Department of Science and Technology of Sichuan Province(19ZDZX0113)Liaoning Revitalization Talents Program(XLYC1807121).
文摘We evaluated bismuth doped cerium oxide catalysts for the continuous synthesis of dimethyl carbonate(DMC)from methanol and carbon dioxide in the absence of a dehydrating agent.Bi_(x)Ce_(1-x)O_(δ)nanocomposites of various compositions(x=0.06-0.24)were coated on a ceramic honeycomb and their structural and catalytic properties were examined.The incorporation of Bi species into the CeO_(2) lattice facilitated controlling of the surface population of oxygen vacancies,which is shown to play a crucial role in the mechanism of this reaction and is an important parameter for the design of ceria-based catalysts.The DMC production rate of the Bi_(x)Ce_(1-x)O_(δ) catalysts was found to be strongly enhanced with increasing Ov concentration.The concentration of oxygen vacancies exhibited a maximum for Bi_(0.12)Ce_(0.88)O_(δ),which afforded the highest DMC production rate.Long-term tests showed stable activity and selectivity of this catalyst over 45 h on-stream at 140°C and a gas-hourly space velocity of 2,880 mL·g_(cat)^(-1)·h^(-1).In-situ modulation excitation diffuse reflection Fourier transform infrared spectroscopy and first-principle calculations indicate that the DMC synthesis occurs through reaction of a bidentate carbonate intermediate with the activated methoxy(-OCH_(3))species.The activation of C0_(2) to form the bidentate carbonate intermediate on the oxygen vacancy sites is identified as highest energy barrier in the reaction pathway and thus is likely the rate-determining step.
基金the National Natural Science Foundation of China(Grant Nos.21663015,21908031 and 51603096)Scientific Research Funds of Yunnan Education Department(Grant No.2021Y111).
文摘Design and exploitation of flame retardant polymers with high electrical conductivity are desired for polymer applications in electronics.Herein,a novel phosphorus-nitrogen intumescent flame retardant was synthesized from pentaerythritol octahydrogen tetraphosphate,phenylphosphonyl dichloride,and aniline.Low-density polyethylene was combined with the flame retardant and multi-walled carbon nanotubes to form a nanocomposite material via a ball-milling and hot-pressing method.The electrical conductivity,mechanical properties,thermal performance,and flame retardancy of the composites were investigated using a four-point probe instrument,universal tensile machine,thermogravimetric analysis,and cone calorimeter tests,respectively.It was found that the addition of multi-walled carbon nanotubes can significantly improve the electrical conductivity and mechanical properties of the low-density polyethylene composites.Furthermore,the combination of multi-walled carbon nanotubes and phosphorus–nitrogen flame retardant remarkably enhances the flame retardancy of matrixes with an observed decrease of the peak heat release rate and total heat release of 49.8%and 51.9%,respectively.This study provides a new and effective methodology to substantially enhance the electrical conductivity and flame retardancy of polymers with an attractive prospect for polymer applications in electrical equipment.
基金National Natural Science Foundation of China,Grant/Award Number:31771929Science and Technology Planning Project of Guangdong Province,Grant/Award Numbers:2021A0505020018,2024A1515013115+2 种基金111 Project,Grant/Award Number:B17018Science and Technology Projects of Guangzhou,Grant/Award Number:2024B03J1270Science and Technology Project of Zhuhai City,Grant/Award Number:ZH220362207200022PWC。
文摘The waste of resources associated with fruit decay is rapidly spreading globally,threatening the interests of relevant practitioners and the health of consumer groups,and demanding precise solutions.Controlling fruit ripening through ethylene reg-ulation is one of the most important strategies for providing high-quality fruits.However,current materials for ethylene regulation still have difficulty realizing their application potential due to high manufacturing costs and performance defi-ciencies.In this review,the ethylene-controlled release materials for ripening based on molecular encapsulation and the ethylene scavengers for preservation based on mechanisms such as oxidation,photodegradation,and adsorption are presented.We discuss and analyze a wide range of materials in terms of mechanism,perfor-mance,potential of applicability,and sustainability.The ethylene release behavior of encapsulating materials depends on the form in which the ethylene binds to the material as well as on environmental factors(humidity and temperature).For ethy-lene scavengers,there are a variety of scavenging mechanisms,but they generally require porous materials as adsorption carriers.We highlight the great opportunity of designing soft crystalline porous materials as efficient ethylene adsorbent due to their unique structural properties.We present this review,including a summary of practical characteristics and deficiencies of various materials,to establish a system-atic understanding of fruit quality assurance materials applied to ethylene regulation,anticipating a promising prospect for these new materials.
文摘The form of a building is among the most critical design aspects concerning building energy consumption.Form-based passive design strategies,like solar control,can significantly reduce heating and cooling demands if implemented early in the design process.In this sense,there is an evident need for tools that can adequately support designers in their decisions.This paper aims to illustrate how geometry-based graphical methods(GGM)can provide effective support in the conceptual design stage.The paper introduces a novel digital framework for designing and analysing shading devices that leverages geometrical models and graphical methods.The digital implementation of GGM allows extending their applicability to threedimensional and non-planar geometries.A comprehensive review of existing methods and tools for the design of shading devices lays the ground for the proposed digital framework,which is then demonstrated through two case studies.The results show that the diagrammatic nature of GGM facilitates a better and more direct understanding of the relationship between form and performance.
文摘This paper opens a series of papers aimed at finalizing the development of the lattice Boltzmann method for complex hydrodynamic systems.The lattice Boltzmann method is introduced at the elementary level of the linear advection equation.Details are provided on lifting the target macroscopic equations to a kinetic equation,and,after that,to the fully discrete lattice Boltzmann scheme.The over-relaxation method is put forward as a cornerstone of the second-order temporal discretization,and its enhancement with the use of the entropy estimate is explained in detail.A new asymptotic expansion of the entropy estimate is derived,and implemented in the sample code.It is shown that the lattice Boltzmann method provides a computationally efficient way of numerically solving the advection equation with a controlled amount of numerical dissipation,while retaining positivity.
基金supported by Swiss Center for Applied Human Toxicology(SCAHT AP22-01)(to RN)。
文摘Parkinson's disease(PD)is the second most common neurodegenerative disorder.The clinical manifestations of PD include motor symptoms,such as bradykinesia,resting tremor,rigidity,and nonmotor symptoms,which include disturbances in sleep,gastrointestinal function,and olfaction.PD misdiagnosis rates have been reported to reach approximately 30%,partly owing to the heterogeneity of parkinsonism with non-PD pathologies,and the differential diagnosis of PD from neurodegenerative diseases such as multiple systemic atrophy(MSA)and progressive supranuclear palsy poses another unmet need.
基金supported by Swiss Center for Applied Human Toxicology(SCAHT AP22-01)(to RN).
文摘Alzheimer’s disease(AD)is the most common cause of dementia,characterized by progressive cognitive decline,and affects over 55 million people worldwide.AD is pathological featured by the aberrant accumulation of amyloid-βplaques,neurofibrillary tangles formed by hyperphosphorylated tau,synaptic loss,and dysfunction of neurotransmitter systems.Evidence from in vivo and autopsy studies has consistently shown that synaptic dysfunction and loss are strongly correlated with cognitive decline in AD,particularly in brain regions such as the hippocampus and cortex,which are critical for memory formation and processing.This perspective highlights recent histopathological findings related to synaptic dysfunction in AD,advancements in the development of imaging and fluid-based biomarkers for synaptic loss,and future studies.
文摘We present a fast Galerkin spectral method to solve logarithmic singular equations on segments. The proposed method uses weighted first-kind Chebyshev polynomials. Conver- gence rates of several orders are obtained for fractional Sobolev spaces H^-1/2 （or H00^-l/2）. Main tools are the approximation properties of the discretization basis, the construction of a suitable Hilbert scale for weighted L2-spaces and local regularity estimates. Numerical experiments are provided to validate our claims,
基金We gratefully acknowledge the funding from the Engineering and Physical Sciences Research Council under the HEC Studentship scheme and grant No.EP/I000801/1.
文摘Realization of the Shan-Chen multiphase flow lattice Boltzmann model is considered in the framework of the higher-order Galilean invariant lattices.The present multiphase lattice Boltzmann model is used in two-dimensional simulation of droplet collisions at high Weber numbers.Results are found to be in a good agreement with experimental findings.
