Outcrop analogue studies play an important role in advancing our comprehension of reservoir architectures,offering insights into hidden reservoir rocks prior to drilling,in a cost-effective manner.These studies contri...Outcrop analogue studies play an important role in advancing our comprehension of reservoir architectures,offering insights into hidden reservoir rocks prior to drilling,in a cost-effective manner.These studies contribute to the delineation of the three-dimensional geometry of geological structures,the characterization of petro-and thermo-physical properties,and the structural geological aspects of reservoir rocks.Nevertheless,several challenges,including inaccessible sampling sites,limited resources,and the dimensional constraints of different laboratories hinder the acquisition of comprehensive datasets.In this study,we employ machine learning techniques to estimate missing data in a petrophysical dataset of fractured Variscan granites from the Cornubian Batholith in Southwest UK.The utilization of mean,k-nearest neighbors,and random forest imputation methods addresses the challenge of missing data,thereby revealing the effectiveness of random forest imputation in providing realistic estimations.Subsequently,supervised classification models are trained to classify samples according to their pluton origins,with promising accuracy achieved by models trained with imputed values.Variable importance ranking of the models showed that the choice of imputation method influences the inferred importance of specific petrophysical properties.While porosity(POR)and grain density(GD)were among important variables,variables with high missingness ratio were not among the top variables.This study demonstrates the value of machine learning in enhancing petrophysical datasets,while emphasizing the importance of careful method selection and model validation for reliable results.The findings contribute to a more informed decision-making process in geothermal exploration and reservoir tion characteriza-efforts,thereby demonstrating the potential of machine learning in advancing subsurface characterization techniques.展开更多
We report on commissioning experiments at the high-energy,high-temperature(HHT)target area at the GSI Helmholtzzentrum für Schwerionenforschung GmbH,Darmstadt,Germany,combining for the first time intense pulses o...We report on commissioning experiments at the high-energy,high-temperature(HHT)target area at the GSI Helmholtzzentrum für Schwerionenforschung GmbH,Darmstadt,Germany,combining for the first time intense pulses of heavy ions from the SIS18 synchrotron with high-energy laser pulses from the PHELIX laser facility.We demonstrate the use of X-ray diagnostic techniques based on intense laserdriven X-ray sources,which will allow probing of large samples volumetrically heated by the intense heavy-ion beams.A new target chamber as well as optical diagnostics for ion-beam characterization and fast pyrometric temperature measurements complement the experimental capabilities.This platform is designed for experiments at the future Facility for Antiproton and Ion Research in Europe GmbH(FAIR),where unprecedented ion-beam intensities will enable the generation of millimeter-sized samples under high-energy-density conditions.展开更多
Carbon fiber reinforced carbon composites(C/Cs),are the most promising high-temperature materials and could be widely applied in aerospace and nucleation fields,owing to their superior performances.However,C/Cs are ve...Carbon fiber reinforced carbon composites(C/Cs),are the most promising high-temperature materials and could be widely applied in aerospace and nucleation fields,owing to their superior performances.However,C/Cs are very susceptible to destructive oxidation and thus fail at elevated temperatures.Though matrix modification and coating technologies with Si-based and ultra-high temperature ceramics(UHTCs)are valid to enhance the oxidation/ablation resistance of C/Cs,it’s not sufficient to satisfy the increasing practical applications,due to the inherent brittleness of ceramics,mismatch issues between coatings and C/C substrates,and the fact that carbonaceous matrices are easily prone to high-temperature oxidation.To effectively solve the aforementioned problems,micro/nano multiscale reinforcing strategies have been developed for C/Cs and/or the coatings over the past two decades,to fabricate C/Cs with high strength and excellent high-temperature stability.This review is to systematically summarize the most recent major and important advancements in some micro/nano multiscale strategies,including nanoparticles,nanowires,carbon nanotubes/fibers,whiskers,graphene,ceramic fibers and hybrid micro/nano structures,for C/Cs and/or the coatings,to achieve high-temperature oxidation/ablation-resistant C/Cs.Finally,this review is concluded with an outlook of major unsolved problems,challenges to be met and future research advice for C/Cs with excellent comprehensive mechanical-thermal performance.It’s hoped that a better understanding of this review will be of high scientific and industrial interest,since it provides unusual and feasible new ideas to develop potential and practical C/Cs with improved high-temperature mechanical and oxidation/ablation-resistant properties.展开更多
Creatures with longer bodies in nature like snakes and eels moving in water commonly generate a large swaying of their bodies or tails,with the purpose of producing significant frictions and collisions between body an...Creatures with longer bodies in nature like snakes and eels moving in water commonly generate a large swaying of their bodies or tails,with the purpose of producing significant frictions and collisions between body and fluid to provide the power of consecutive forward force.This swaying can be idealized by considering oscillations of a soft beam immersed in water when waves of vibration travel down at a constant speed.The present study employs a kind of large deformations induced by nonlinear vibrations of a soft pipe conveying fluid to design an underwater bio-inspired snake robot that consists of a rigid head and a soft tail.When the head is fixed,experiments show that a second mode vibration of the tail in water occurs as the internal flow velocity is beyond a critical value.Then the corresponding theoretical model based on the absolute nodal coordinate formulation(ANCF)is established to describe nonlinear vibrations of the tail.As the head is free,the theoretical modeling is combined with the computational fluid dynamics(CFD)analysis to construct a fluid-structure interaction(FSI)simulation model.The swimming speed and swaying shape of the snake robot are obtained through the FSI simulation model.They are in good agreement with experimental results.Most importantly,it is demonstrated that the propulsion speed can be improved by 21%for the robot with vibrations of the tail compared with that without oscillations in the pure jet mode.This research provides a new thought to design driving devices by using nonlinear flow-induced vibrations.展开更多
Carbon nanotubes(CNTs) are fabricated in carbon cloth by ultilizing the waste gasses when fabricating hafnium carbide nanowires(HfC_(NWS)) through thermal pyrolysis of Hf-containing polymer precursor.The formed HfC_(N...Carbon nanotubes(CNTs) are fabricated in carbon cloth by ultilizing the waste gasses when fabricating hafnium carbide nanowires(HfC_(NWS)) through thermal pyrolysis of Hf-containing polymer precursor.The formed HfC_(NWS) are distributed uniformly on the surface of the carbon fibers in carbon/carbon(C/C) composites and display perfect single crystal appearance.The pyrolysis of the Hf-containing organic precursor provides hafnium and carbon source for the growth of HfC_(NWS).The released waste gasses containing CO,CH4and CO_(2)are the main carbon source for the growth of CNTs.Specifically,the flexural strength of HfC_(NWS) reinforced carbon/carbon(HfC_(NWS)-C/C) composites is enhanced by ~105% compared with pure C/C,and the CNTs/carbon cloth also displays improved electrochemical performance with respect to capacitor applications.The present study introduces a novel sustainable and eco-friendly process related to polymer-derived ceramics to form advanced ceramic nanocomposites and proposes a deep understanding of the growth mechanism of CNTs.展开更多
Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forest...Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forestry,combining timber production with the supply of other forest ecosystem services.However,it is unclear which forest types provide which ecosystem services and to what extent forests primarily managed for timber already supply multiple ecosystem services.Based on a comprehensive dataset collected across 150 forest plots in three regions differing in management intensity and species composition,we develop models to predict the potential supply of 13 ecosystem services.We use those models to assess the level of multifunctionality of managed forests at the national level using national forest inventory data.Results:Looking at the potential supply of ecosystem services,we found trade-offs(e.g.between both bark beetle control or dung decomposition and both productivity or soil carbon stocks)as well as synergies(e.g.for temperature regulation,carbon storage and culturally interesting plants)across the 53 most dominant forest types in Germany.No single forest type provided all ecosystem services equally.Some ecosystem services showed comparable levels across forest types(e.g.decomposition or richness of saprotrophs),while others varied strongly,depending on forest structural attributes(e.g.phosphorous availability or cover of edible plants)or tree species composition(e.g.potential nitrification activity).Variability in potential supply of ecosystem services was only to a lesser extent driven by environmental conditions.However,the geographic variation in ecosystem function supply across Germany was closely linked with the distribution of main tree species.Conclusions:Our results show that forest multifunctionality is limited to subsets of ecosystem services.The importance of tree species composition highlights that a lack of multifunctionality at the stand level can be compensated by managing forests at the landscape level,when stands of complementary forest types are combined.These results imply that multi-purpose forestry should be based on a variety of forest types requiring coordinated planning across larger spatial scales.展开更多
The environmentally-friendly(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(x=0,0.02,0.04,0.06,0.08)relaxor ferroelectric ceramics were prepared by the conventional solid-state method and sintered in air at 1...The environmentally-friendly(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(x=0,0.02,0.04,0.06,0.08)relaxor ferroelectric ceramics were prepared by the conventional solid-state method and sintered in air at 1400°C for 2 h.SEM and XRD analyses were utilized to study the surface morphologies and the crystalline structures,respectively.The effects of BaMg_(0.1)Ta_(0.9))O_(3)on the phase transformation,dielectric and ferroelectric properties of Ba(Zr_(1/3)Ti_(2/3))O_(3)ceramics were also investigated.It is found that the average grain size of(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(BZT-BMT)perovskite single-phase ceramics decreases as the content of BaMg_(0.1)Ta_(0.9))O_(3)(BMT)increases.The relaxor ferroelectric behavior with diffuse phase transition and well-defined frequency dispersion of dielectric maximum temperature is found for the ceramic with increasing x values.0.98BZT-0.02BMT ceramic shows very good dielectric properties with the relative permittivity and the dielectric loss,measured at 100 k Hz as 6034 and 0.01399 respectively at room temperature.Both remnant polarization and coercive field decreased with increasing BMT content,indicating a transition from the ferroelectric phase to the paraelectric phase at room temperature.展开更多
We present in situ measurements of spectrally resolved X-ray scattering and X-ray diffraction from monocrystalline diamond samples heatedwith an intense pulse of heavy ions.In this way,we determine the samples’heatin...We present in situ measurements of spectrally resolved X-ray scattering and X-ray diffraction from monocrystalline diamond samples heatedwith an intense pulse of heavy ions.In this way,we determine the samples’heating dynamics and their microscopic and macroscopic structuralintegrity over a timespan of several microseconds.Connecting the ratio of elastic to inelastic scattering with state-of-the-art density functionaltheory molecular dynamics simulations allows the inference of average temperatures around 1300 K,in agreement with predictions fromstopping power calculations.The simultaneous diffraction measurements show no hints of any volumetric graphitization of the material,butdo indicate the onset of fracture in the diamond sample.Our experiments pave the way for future studies at the Facility for Antiproton andIon Research,where a substantially increased intensity of the heavy ion beam will be available.展开更多
Grasslands are among the most biodiverse and ecologically important ecosystems,and yet,they are increasingly threatened by land-use intensification and biodiversity loss.Addressing these challenges requires a holistic...Grasslands are among the most biodiverse and ecologically important ecosystems,and yet,they are increasingly threatened by land-use intensification and biodiversity loss.Addressing these challenges requires a holistic approach that integrates knowledge across disciplines and actively engages stakeholders beyond academia.This article explores the role of collaboration,interdisciplinarity,and transdisciplinarity in grassland research,with a focus on two German key projects.The Biodiversity Exploratories are one of the largest long-term research projects investigating biodiversity and ecosystem function across land-use gradients.The BioDivKultur project examines the effects of mowing on grassland arthropods by bridging various academic and practical perspectives.Both projects highlight how integrated research approaches can generate scientifically rigorous and socially relevant solutions for biodiversity conservation while also revealing the practical and conceptual challenges of such cooperation.This article emphasizes the need for sustained cooperation,mutual learning,and effective knowledge transfer to bridge science and practice in addressing the complex,multifaceted issues of grassland ecosystems.展开更多
Piezoelectric materials are capable of converting between mechanical and electrical energy,and are suitable for sensing,actuating and energy harvesting.While most conventional piezoelectric materials are brittle solid...Piezoelectric materials are capable of converting between mechanical and electrical energy,and are suitable for sensing,actuating and energy harvesting.While most conventional piezoelectric materials are brittle solids,flexible piezoelectric materials(FPM)retain functionality even under bending and stretching conditions.This characteristic has garnered increasing attention in recent years,particularly for wearable devices,where the ability to adapt to dynamic human movements is essential.In addition,wearable devices also demand excellent conformability,durability,and adaptability to miniaturization.FPM emerge as a promising solution that meet all these requirements.This review thus aims to offer a comprehensive summary of recent advances in the field of FPM,including piezoelectric polymers,composites,and inorganic flexible films.We introduce and categorize the specific features of these materials and highlight their emerging applications in electronic devices,and comment on the prospect of FPM as well as their potential challenges.展开更多
In this white paper,we present the potential of the enhanced X-ray timing and polarimetry(eXTP)mission to constrain the equation of state of dense matter in neutron stars,exploring regimes not directly accessible to t...In this white paper,we present the potential of the enhanced X-ray timing and polarimetry(eXTP)mission to constrain the equation of state of dense matter in neutron stars,exploring regimes not directly accessible to terrestrial experiments.By observing a diverse population of neutron stars—including isolated objects,X-ray bursters,and accreting systems—eXTP’s unique combination of timing,spectroscopy,and polarimetry enables high-precision measurements of compactness,spin,surface temperature,polarimetric signals,and timing irregularity.These multifaceted observations,combined with advances in theoretical modeling,pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars.Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences,the eXTP mission is planned to be launched in early 2030.展开更多
In order to reach the highest intensities,modern laser systems use adaptive optics to control their beam quality.Ideally,the focal spot is optimized after the compression stage of the system in order to avoid spatio-t...In order to reach the highest intensities,modern laser systems use adaptive optics to control their beam quality.Ideally,the focal spot is optimized after the compression stage of the system in order to avoid spatio-temporal couplings.This also requires a wavefront sensor after the compressor,which should be able to measure the wavefront on-shot.At PHELIX,we have developed an ultra-compact post-compressor beam diagnostic due to strict space constraints,measuring the wavefront over the full aperture of 28 cm.This system features all-reflective imaging beam transport and a high dynamic range in order to measure the wavefront in alignment mode as well as on shot.展开更多
Since the 1960s,a new class of Si-based advanced ceramics called polymer-derived ceramics(PDCs)has been widely reported because of their unique capabilities to produce various ceramic materials(e.g.,ceramic fibers,cer...Since the 1960s,a new class of Si-based advanced ceramics called polymer-derived ceramics(PDCs)has been widely reported because of their unique capabilities to produce various ceramic materials(e.g.,ceramic fibers,ceramic matrix composites,foams,films,and coatings)and their versatile applications.Particularly,due to their promising structural and functional properties for energy conversion and storage,the applications of PDCs in these fields have attracted much attention in recent years.This review highlights the recent progress in the PDC field with the focus on energy conversion and storage applications.Firstly,a brief introduction of the Si-based polymer-derived ceramics in terms of synthesis,processing,and microstructure characterization is provided,followed by a summary of PDCs used in energy conversion systems(mainly in gas turbine engines),including fundamentals and material issues,ceramic matrix composites,ceramic fibers,thermal and environmental barrier coatings,as well as high-temperature sensors.Subsequently,applications of PDCs in the field of energy storage are reviewed with a strong focus on anode materials for lithium and sodium ion batteries.The possible applications of the PDCs in Li–S batteries,supercapacitors,and fuel cells are discussed as well.Finally,a summary of the reported applications and perspectives for future research with PDCs are presented.展开更多
Autonomous materials discovery with desired properties is one of the ultimate goals for materials science,and the current studies have been focusing mostly on high-throughput screening based on density functional theo...Autonomous materials discovery with desired properties is one of the ultimate goals for materials science,and the current studies have been focusing mostly on high-throughput screening based on density functional theory calculations and forward modeling of physical properties using machine learning.Applying the deep learning techniques,we have developed a generative model,which can predict distinct stable crystal structures by optimizing the formation energy in the latent space.It is demonstrated that the optimization of physical properties can be integrated into the generative model as on-top screening or backward propagator,both with their own advantages.Applying the generative models on the binary Bi-Se system reveals that distinct crystal structures can be obtained covering the whole composition range,and the phases on the convex hull can be reproduced after the generated structures are fully relaxed to the equilibrium.The method can be extended to multicomponent systems for multi-objective optimization,which paves the way to achieve the inverse design of materials with optimal properties.展开更多
During selective laser sintering(SLS),the microstructure evolution and local temperature variation interact mutually.Application of conventional isothermal sintering model is thereby insufficient to describe SLS.In th...During selective laser sintering(SLS),the microstructure evolution and local temperature variation interact mutually.Application of conventional isothermal sintering model is thereby insufficient to describe SLS.In this work,we construct our model from entropy level,and derive the non-isothermal kinetics for order parameters along with the heat transfer equation coupled with microstructure evolution.Influences from partial melting and laser-powder interaction are also addressed.We then perform 3D finite element non-isothermal phase-field simulations of the SLS single scan.To confront the high computation cost,we propose a novel algorithm analogy to minimum coloring problem and manage to simulate a system of 200 grains with grain tracking algorithm using as low as 8 non-conserved order parameters.Specifically,applying the model to SLS of the stainless steel 316L powder,we identify the influences of laser power and scan speed on microstructural features,including the porosity,surface morphology,temperature profile,grain geometry,and densification.We further validate the first-order kinetics of the transient porosity during densification,and demonstrate the applicability of the developed model in predicting the linkage of densification factor to the specific energy input during SLS.展开更多
Microneedle-based microfluidic systems have a great potential to become well-accepted medical devices for simple,accurate,and painless drug delivery and lab-on-a-chip diagnostics.In this work,we report on a novel hybr...Microneedle-based microfluidic systems have a great potential to become well-accepted medical devices for simple,accurate,and painless drug delivery and lab-on-a-chip diagnostics.In this work,we report on a novel hybrid approach combining femtosecond direct laser written microneedles with femtosecond laser generated microfluidic channels providing an important step towards versatile medical point-of-care systems.Hollow microneedle arrays are fabricated by a laser system designed for two-photon polymerization applications.Compression tests of two different types of truncated cone-shaped microneedle arrays prepared from OrmoComp^(■)give information about the microneedle mechanical strength,and the results are compared to skin insertion forces.Three-dimensional microchannels are directly created inside PMMA bulk material by an ultrashort pulse laser system with vertical channels having adjustable cross-sectional areas,which allow attaching of microneedles to the microfluidic system.A comprehensive parameter study varying pulse duration and repetition rate is performed on two-photon polymerization to identify an optimal laser power range for fabricating microneedles using the same pulse duration and repetition rate as for microchannels.This addresses the advantage of a single laser system process that overcomes complex fabrication methods.A proof of concept flow test with a rhodamine B dye solution in distilled water demonstrates that the combination of microneedles and microchannels qualifies for microfluidic injection and extraction applications.展开更多
Dielectrophoresis(DEP)describes the motion of suspended objects when exposed to an inhomogeneous electric field.It has been successful as a method for parallel and site-selective assembling of nanotubes from a dispers...Dielectrophoresis(DEP)describes the motion of suspended objects when exposed to an inhomogeneous electric field.It has been successful as a method for parallel and site-selective assembling of nanotubes from a dispersion into a sophisticated device architecture.Researchers have conducted extensive works to understand the DEP of nanotubes in aqueous ionic surfactant solutions.However,only recently,DEP was applied to polymer-wrapped single-walled carbon nanotubes(SWCNTs)in organic solvents due to the availability of ultra-pure SWCNT content.In this paper,the focus is on the difference between the DEP in aqueous and organic solutions.It starts with an introduction into the DEP of carbon nanotubes(CNT-DEP)to provide a comprehensive,in-depth theoretical background before discussing in detail the experimental procedures and conditions.For academic interests,this work focuses on the CNT-DEP deposition scheme,discusses the importance of the electrical double layer,and employs finite element simulations to optimize CNT-DEP deposition condition with respect to the experimental observation.An important outcome is an understanding of why DEP in organic solvents allows for the deposition and alignment of SWCNTs in low-frequency and even static electric fields,and why the response of semiconducting SWCNTs(s-SWCNTs)is strongly enhanced in non-conducting,weakly polarizable media.Strategies to further improve CNT-DEP for s-SWCNT-relevant applications are given as well.Overall,this work should serve as a practical guideline to select the appropriate setting for effective CNT DEPs.展开更多
Silica(SiO_(2))is an abundant material with a wide range of applications.Despite much progress,the atomistic modelling of the different forms of silica has remained a challenge.Here we show that by combining density-f...Silica(SiO_(2))is an abundant material with a wide range of applications.Despite much progress,the atomistic modelling of the different forms of silica has remained a challenge.Here we show that by combining density-functional theory at the SCAN functional level with machine-learning-based interatomic potential fitting,a range of condensed phases of silica can be accurately described.We present a Gaussian approximation potential model that achieves high accuracy for the thermodynamic properties of the crystalline phases,and we compare its performance(and performance–cost trade-off)with that of multiple empirically fitted interatomic potentials for silica.We also include amorphous phases,assessing the ability of the potentials to describe structures of melt-quenched glassy silica,their energetic stability,and the high-pressure structural transition to a mainly sixfold-coordinated phase.We suggest that rather than standing on their own,machine-learned potentials for silica may be used in conjunction with suitable empirical models,each having a distinct role and complementing the other,by combining the advantages of the long simulation times afforded by empirical potentials and the near-quantum-mechanical accuracy of machine-learned potentials.This way,our work is expected to advance atomistic simulations of this key material and to benefit further computational studies in the field.展开更多
Targets with microstructured front surfaces have shown great potential in improving high-intensity laser–matter interaction.We present cone-shaped microstructures made out of silicon and titanium created by ultrashor...Targets with microstructured front surfaces have shown great potential in improving high-intensity laser–matter interaction.We present cone-shaped microstructures made out of silicon and titanium created by ultrashort laser pulse processing with different characteristics.In addition,we illustrate a process chain based on moulding to recreate the laser-processed samples out of polydimethylsiloxane,polystyrol and copper.With all described methods,samples of large sizes can be manufactured,therefore allowing time-efficient,cost-reduced and reliable ways to fabricate large quantities of identical targets.展开更多
The atomic structural features and the mechanical properties of amorphous silicoboron carbonitride ceramics with 13 different compositions in the Si–BN–C phase diagram are investigated employing ab-initio calculatio...The atomic structural features and the mechanical properties of amorphous silicoboron carbonitride ceramics with 13 different compositions in the Si–BN–C phase diagram are investigated employing ab-initio calculations.Both chemical bonds and local structures within the amorphous network relate to the elemental composition.The distribution of nine types of chemical bonds is composition-dependent,where the B–C,Si–N,Si–C,and B–N bonds hold a large proportion for all compositions.Si prefers to be tetrahedrally coordinated,while B and N prefer sp^(2)-like trigonal coordination.In the case of C,the tetrahedral coordination is predominant at relatively low C contents,while the trigonal coordination is found to be the main feature with the increasing C content.Such local structural characteristics greatly influence the mechanical properties of SiBCN ceramics.Among the studied amorphous ceramics,SiB_(2)C_(3)N_(2) and SiB_(3)C_(2)N_(3) with low Si contents and moderate C and/or BN contents have high elastic moduli,high tensile/shear strengths,and good debonding capability.The increment of Si,C,and BN contents on this basis results in the decrease of mechanical properties.The increasing Si content leads to the increment of Si-contained bonds that reduce the bond strength of SiBCN ceramics,while the latter two cases are attributed to the raise of sp^(2)-like trigonal configuration of C and BN.These discoveries are expected to guide the composition-tailored optimization of SiBCN ceramics.展开更多
文摘Outcrop analogue studies play an important role in advancing our comprehension of reservoir architectures,offering insights into hidden reservoir rocks prior to drilling,in a cost-effective manner.These studies contribute to the delineation of the three-dimensional geometry of geological structures,the characterization of petro-and thermo-physical properties,and the structural geological aspects of reservoir rocks.Nevertheless,several challenges,including inaccessible sampling sites,limited resources,and the dimensional constraints of different laboratories hinder the acquisition of comprehensive datasets.In this study,we employ machine learning techniques to estimate missing data in a petrophysical dataset of fractured Variscan granites from the Cornubian Batholith in Southwest UK.The utilization of mean,k-nearest neighbors,and random forest imputation methods addresses the challenge of missing data,thereby revealing the effectiveness of random forest imputation in providing realistic estimations.Subsequently,supervised classification models are trained to classify samples according to their pluton origins,with promising accuracy achieved by models trained with imputed values.Variable importance ranking of the models showed that the choice of imputation method influences the inferred importance of specific petrophysical properties.While porosity(POR)and grain density(GD)were among important variables,variables with high missingness ratio were not among the top variables.This study demonstrates the value of machine learning in enhancing petrophysical datasets,while emphasizing the importance of careful method selection and model validation for reliable results.The findings contribute to a more informed decision-making process in geothermal exploration and reservoir tion characteriza-efforts,thereby demonstrating the potential of machine learning in advancing subsurface characterization techniques.
基金supported by GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, as part of the R & D Project No. SI-URDK2224 with the University of Rostocksupport by the Federal Ministry of Education and Research (BMBF) under Grant No. 05P21RFFA2supported by the Helmholtz Association under Grant No. ERC-RA-0041。
文摘We report on commissioning experiments at the high-energy,high-temperature(HHT)target area at the GSI Helmholtzzentrum für Schwerionenforschung GmbH,Darmstadt,Germany,combining for the first time intense pulses of heavy ions from the SIS18 synchrotron with high-energy laser pulses from the PHELIX laser facility.We demonstrate the use of X-ray diagnostic techniques based on intense laserdriven X-ray sources,which will allow probing of large samples volumetrically heated by the intense heavy-ion beams.A new target chamber as well as optical diagnostics for ion-beam characterization and fast pyrometric temperature measurements complement the experimental capabilities.This platform is designed for experiments at the future Facility for Antiproton and Ion Research in Europe GmbH(FAIR),where unprecedented ion-beam intensities will enable the generation of millimeter-sized samples under high-energy-density conditions.
基金supported by the National Natural Science Foundation of China(Nos.91860203,51821091,51872239,52002321 and 52061135102)the China Postdoctoral Science Foundation(No.2019M660265)+3 种基金the Fundamental Research Funds for the Central Universities(China,Nos.G2019KY05116,G2020KY05125)the Innovation Talent Promotion Plan of Shaanxi Province for Science and Technology Innovation Team(No.2020TD003)the Creative Research Foundation of Science and Technology on Thermostructural Composite Materials Laboratory(Nos.614291102010517,5050200015 and 5150200033)the Shaanxi Provincial Education Department of China(No.2020JQ-170)。
文摘Carbon fiber reinforced carbon composites(C/Cs),are the most promising high-temperature materials and could be widely applied in aerospace and nucleation fields,owing to their superior performances.However,C/Cs are very susceptible to destructive oxidation and thus fail at elevated temperatures.Though matrix modification and coating technologies with Si-based and ultra-high temperature ceramics(UHTCs)are valid to enhance the oxidation/ablation resistance of C/Cs,it’s not sufficient to satisfy the increasing practical applications,due to the inherent brittleness of ceramics,mismatch issues between coatings and C/C substrates,and the fact that carbonaceous matrices are easily prone to high-temperature oxidation.To effectively solve the aforementioned problems,micro/nano multiscale reinforcing strategies have been developed for C/Cs and/or the coatings over the past two decades,to fabricate C/Cs with high strength and excellent high-temperature stability.This review is to systematically summarize the most recent major and important advancements in some micro/nano multiscale strategies,including nanoparticles,nanowires,carbon nanotubes/fibers,whiskers,graphene,ceramic fibers and hybrid micro/nano structures,for C/Cs and/or the coatings,to achieve high-temperature oxidation/ablation-resistant C/Cs.Finally,this review is concluded with an outlook of major unsolved problems,challenges to be met and future research advice for C/Cs with excellent comprehensive mechanical-thermal performance.It’s hoped that a better understanding of this review will be of high scientific and industrial interest,since it provides unusual and feasible new ideas to develop potential and practical C/Cs with improved high-temperature mechanical and oxidation/ablation-resistant properties.
基金the National Natural Science Foundation of China(No.12072119)。
文摘Creatures with longer bodies in nature like snakes and eels moving in water commonly generate a large swaying of their bodies or tails,with the purpose of producing significant frictions and collisions between body and fluid to provide the power of consecutive forward force.This swaying can be idealized by considering oscillations of a soft beam immersed in water when waves of vibration travel down at a constant speed.The present study employs a kind of large deformations induced by nonlinear vibrations of a soft pipe conveying fluid to design an underwater bio-inspired snake robot that consists of a rigid head and a soft tail.When the head is fixed,experiments show that a second mode vibration of the tail in water occurs as the internal flow velocity is beyond a critical value.Then the corresponding theoretical model based on the absolute nodal coordinate formulation(ANCF)is established to describe nonlinear vibrations of the tail.As the head is free,the theoretical modeling is combined with the computational fluid dynamics(CFD)analysis to construct a fluid-structure interaction(FSI)simulation model.The swimming speed and swaying shape of the snake robot are obtained through the FSI simulation model.They are in good agreement with experimental results.Most importantly,it is demonstrated that the propulsion speed can be improved by 21%for the robot with vibrations of the tail compared with that without oscillations in the pure jet mode.This research provides a new thought to design driving devices by using nonlinear flow-induced vibrations.
基金financial supports of this work by the National Natural Science Foundation of China(Nos.52130205,51727804,91860203,52061135102)the National Key R&D Program of China(No.2021YFA0715803)the China Scholarship Program,2020(CSC No.202006290179)。
文摘Carbon nanotubes(CNTs) are fabricated in carbon cloth by ultilizing the waste gasses when fabricating hafnium carbide nanowires(HfC_(NWS)) through thermal pyrolysis of Hf-containing polymer precursor.The formed HfC_(NWS) are distributed uniformly on the surface of the carbon fibers in carbon/carbon(C/C) composites and display perfect single crystal appearance.The pyrolysis of the Hf-containing organic precursor provides hafnium and carbon source for the growth of HfC_(NWS).The released waste gasses containing CO,CH4and CO_(2)are the main carbon source for the growth of CNTs.Specifically,the flexural strength of HfC_(NWS) reinforced carbon/carbon(HfC_(NWS)-C/C) composites is enhanced by ~105% compared with pure C/C,and the CNTs/carbon cloth also displays improved electrochemical performance with respect to capacitor applications.The present study introduces a novel sustainable and eco-friendly process related to polymer-derived ceramics to form advanced ceramic nanocomposites and proposes a deep understanding of the growth mechanism of CNTs.
基金funded through the project‘Bio Holz’(grant no.01LC1323A)in the funding program‘Research for the Implementation of the National Biodiversity Strategy(F&U NBS)’by the German Federal Ministry for Education and Research(BMBF)and the German Federal Agency for Nature Conservation(Bf N)with funds provided by the German Federal Ministry for the Environment,Nature Conservation,Building and Nuclear Safety(BMUB)supported by the DFG Priority Program 1374‘Infrastructure-Biodiversity-Exploratories’。
文摘Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forestry,combining timber production with the supply of other forest ecosystem services.However,it is unclear which forest types provide which ecosystem services and to what extent forests primarily managed for timber already supply multiple ecosystem services.Based on a comprehensive dataset collected across 150 forest plots in three regions differing in management intensity and species composition,we develop models to predict the potential supply of 13 ecosystem services.We use those models to assess the level of multifunctionality of managed forests at the national level using national forest inventory data.Results:Looking at the potential supply of ecosystem services,we found trade-offs(e.g.between both bark beetle control or dung decomposition and both productivity or soil carbon stocks)as well as synergies(e.g.for temperature regulation,carbon storage and culturally interesting plants)across the 53 most dominant forest types in Germany.No single forest type provided all ecosystem services equally.Some ecosystem services showed comparable levels across forest types(e.g.decomposition or richness of saprotrophs),while others varied strongly,depending on forest structural attributes(e.g.phosphorous availability or cover of edible plants)or tree species composition(e.g.potential nitrification activity).Variability in potential supply of ecosystem services was only to a lesser extent driven by environmental conditions.However,the geographic variation in ecosystem function supply across Germany was closely linked with the distribution of main tree species.Conclusions:Our results show that forest multifunctionality is limited to subsets of ecosystem services.The importance of tree species composition highlights that a lack of multifunctionality at the stand level can be compensated by managing forests at the landscape level,when stands of complementary forest types are combined.These results imply that multi-purpose forestry should be based on a variety of forest types requiring coordinated planning across larger spatial scales.
基金fully sponsored by the National Demonstration Center for Experimental Materials Science and Engineering Education(Jiangsu University of Science and Technology,China)funded by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions,China。
文摘The environmentally-friendly(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(x=0,0.02,0.04,0.06,0.08)relaxor ferroelectric ceramics were prepared by the conventional solid-state method and sintered in air at 1400°C for 2 h.SEM and XRD analyses were utilized to study the surface morphologies and the crystalline structures,respectively.The effects of BaMg_(0.1)Ta_(0.9))O_(3)on the phase transformation,dielectric and ferroelectric properties of Ba(Zr_(1/3)Ti_(2/3))O_(3)ceramics were also investigated.It is found that the average grain size of(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(BZT-BMT)perovskite single-phase ceramics decreases as the content of BaMg_(0.1)Ta_(0.9))O_(3)(BMT)increases.The relaxor ferroelectric behavior with diffuse phase transition and well-defined frequency dispersion of dielectric maximum temperature is found for the ceramic with increasing x values.0.98BZT-0.02BMT ceramic shows very good dielectric properties with the relative permittivity and the dielectric loss,measured at 100 k Hz as 6034 and 0.01399 respectively at room temperature.Both remnant polarization and coercive field decreased with increasing BMT content,indicating a transition from the ferroelectric phase to the paraelectric phase at room temperature.
基金support by the Federal Ministry of Education and Research(BMBF)under Grant No.05P21RFFA2supported by the Helmholtz Association under Grant No.ERC-RA-0041.
文摘We present in situ measurements of spectrally resolved X-ray scattering and X-ray diffraction from monocrystalline diamond samples heatedwith an intense pulse of heavy ions.In this way,we determine the samples’heating dynamics and their microscopic and macroscopic structuralintegrity over a timespan of several microseconds.Connecting the ratio of elastic to inelastic scattering with state-of-the-art density functionaltheory molecular dynamics simulations allows the inference of average temperatures around 1300 K,in agreement with predictions fromstopping power calculations.The simultaneous diffraction measurements show no hints of any volumetric graphitization of the material,butdo indicate the onset of fracture in the diamond sample.Our experiments pave the way for future studies at the Facility for Antiproton andIon Research,where a substantially increased intensity of the heavy ion beam will be available.
基金Deutsche Forschungsgemeinschaft,Grant/Award Number:BL 960/8-5Bundesministerium für Bildung und Forschung,Grant/Award Number:16LW0074K。
文摘Grasslands are among the most biodiverse and ecologically important ecosystems,and yet,they are increasingly threatened by land-use intensification and biodiversity loss.Addressing these challenges requires a holistic approach that integrates knowledge across disciplines and actively engages stakeholders beyond academia.This article explores the role of collaboration,interdisciplinarity,and transdisciplinarity in grassland research,with a focus on two German key projects.The Biodiversity Exploratories are one of the largest long-term research projects investigating biodiversity and ecosystem function across land-use gradients.The BioDivKultur project examines the effects of mowing on grassland arthropods by bridging various academic and practical perspectives.Both projects highlight how integrated research approaches can generate scientifically rigorous and socially relevant solutions for biodiversity conservation while also revealing the practical and conceptual challenges of such cooperation.This article emphasizes the need for sustained cooperation,mutual learning,and effective knowledge transfer to bridge science and practice in addressing the complex,multifaceted issues of grassland ecosystems.
基金supported by National Natural Science Foundation of China(No.12474213,52032005,82225012,52325204,and U22A20254)National Key Research and Development Program of China(No.2024YFF1400700)supported by Wuzhen Laboratory,and Deutsche Forschungsgemeinschaft(No.414311761).
文摘Piezoelectric materials are capable of converting between mechanical and electrical energy,and are suitable for sensing,actuating and energy harvesting.While most conventional piezoelectric materials are brittle solids,flexible piezoelectric materials(FPM)retain functionality even under bending and stretching conditions.This characteristic has garnered increasing attention in recent years,particularly for wearable devices,where the ability to adapt to dynamic human movements is essential.In addition,wearable devices also demand excellent conformability,durability,and adaptability to miniaturization.FPM emerge as a promising solution that meet all these requirements.This review thus aims to offer a comprehensive summary of recent advances in the field of FPM,including piezoelectric polymers,composites,and inorganic flexible films.We introduce and categorize the specific features of these materials and highlight their emerging applications in electronic devices,and comment on the prospect of FPM as well as their potential challenges.
基金supported by China’s Space Origins Exploration Programsupported by the National Natural Science Foundation of China (Grant No.12273028)+36 种基金support from ERC Consolidator (Grant No.865768) AEONSsupport from NWO grant ENW-XL OCENW.XL21.XL21.038the support of the CNESsupported by the National Natural Science Foundation of China (Grant No.12333007)the International Partnership Program of Chinese Academy of Sciences (Grant No.113111KYSB20190020)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA15020100)supported by the China National Postdoctoral Program for Innovation Talents (Grant No.BX20240223)the China Postdoctoral Science Foundation Funded Project (Grant No.2024M761948)support from a Ramon y Cajal fellowship (Grant No.RYC2021-032718-I) financed by MCIN/AEI/10.13039/501100011033 and the European Union Next Generation EU/PRTRsupported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region (Grant No.2023D01E20)the National SKA Program of China (Grant No.2020SKA0120300)supported by the National Natural Science Foundation of China (Grant Nos.12033001,and 12473039)supported by Zhejiang Provincial Natural Science Foundation of China (Grant No.LQ24A030002)supported by the National Natural Science Foundation of China (Grant No.12003009)supported by the National SKA Program of China (Grant No.2020SKA0120200)the National Natural Science Foundation of China (Grant No.12041303)supported by the National Natural Science Foundation of China (Grant No.1227303)supported by the National SKA Program of China (Grant No.2020SKA0120300)the Beijing Natural Science Foundation (Grant No.1242018)the Max Planck Partner Group Program funded by the Max Planck Societysupported by JSPS KAKENHI (the Japan Society for the Promotion of Science,Grantsin-Aid for Scientific Research) (Grant Nos.23K19056,and 25K17403)supported by the National Natural Science Foundation of China (Grant No.12175109)support from FCT (Fundacao para a Ciência e a Tecnologia,I.P.,Portugal) (Grant Nos.UIDB/04564/2020,and 2022.06460.PTDC)supported from the program Unidad de Excelencia María de Maeztu CEX2020-001058-Mfrom the project PID2022-139427NB-I00 financed by the Spanish MCIN/AEI/10.13039/501100011033/FEDER,UE (FSE+)by the CRC-TR 211 “Strong-interaction matter under extreme conditions” -project Nr.315477589-TRR 211support from grant PID2021-124581OB-I0,PID2024-155316NB-I00,and 2021SGR00426supported by the National Natural Science Foundation of China (Grant No.12122513)supported in part by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant No.101020842)by the Deutsche Forschungsgemeinschaft (DFG,German Research Foundation)-Project-ID 279384907-SFB 1245support from the ERC Consolidator (Grant No.101002352) (LOVENEST)supported by the European Research Council (ERC) via the Consolidator Grant “MAGNESIA” (Grant No.817661)the Proof of Concept “Deep Space Pulse” (Grant No.101189496)the Catalan grant SGR2021-01269the Spanish grant ID2023-153099NA-I00the program Unidad de Excelencia Maria de Maeztu CEX2020-001058-Msupported by the Research Council of Finland (Grant No.354533).
文摘In this white paper,we present the potential of the enhanced X-ray timing and polarimetry(eXTP)mission to constrain the equation of state of dense matter in neutron stars,exploring regimes not directly accessible to terrestrial experiments.By observing a diverse population of neutron stars—including isolated objects,X-ray bursters,and accreting systems—eXTP’s unique combination of timing,spectroscopy,and polarimetry enables high-precision measurements of compactness,spin,surface temperature,polarimetric signals,and timing irregularity.These multifaceted observations,combined with advances in theoretical modeling,pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars.Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences,the eXTP mission is planned to be launched in early 2030.
基金This work has received partial funding from the EUROfusion Consortium,funded by the European Union via the Euratom Research and Training Programme(Grant Agreement No.101052200—EUROfusion).
文摘In order to reach the highest intensities,modern laser systems use adaptive optics to control their beam quality.Ideally,the focal spot is optimized after the compression stage of the system in order to avoid spatio-temporal couplings.This also requires a wavefront sensor after the compressor,which should be able to measure the wavefront on-shot.At PHELIX,we have developed an ultra-compact post-compressor beam diagnostic due to strict space constraints,measuring the wavefront over the full aperture of 28 cm.This system features all-reflective imaging beam transport and a high dynamic range in order to measure the wavefront in alignment mode as well as on shot.
基金Zhaoju Yu thanks the National Natural Science Foundation of China(Nos.51872246 and 52061135102)for financial supportQingbo Wen thanks the National Natural Science Foundation of China(No.52102085)+3 种基金the State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China(No.621022117)Fangmu Qu acknowledges the financial support by the China Scholarship Council(CSC,No.201904910776)This review also originated from the Research Training Group at TU Darmstadt and Karlsruhe Institute of Technology(KIT)entitled“Materials Composites from Composite Materials”funded by the Deutsche Forschungsgemeinschaft(DFG,No.GRK 2561)Magdalena Graczyk-Zajac acknowledges DFG support in the frame of the project GR 4440/4-1.
文摘Since the 1960s,a new class of Si-based advanced ceramics called polymer-derived ceramics(PDCs)has been widely reported because of their unique capabilities to produce various ceramic materials(e.g.,ceramic fibers,ceramic matrix composites,foams,films,and coatings)and their versatile applications.Particularly,due to their promising structural and functional properties for energy conversion and storage,the applications of PDCs in these fields have attracted much attention in recent years.This review highlights the recent progress in the PDC field with the focus on energy conversion and storage applications.Firstly,a brief introduction of the Si-based polymer-derived ceramics in terms of synthesis,processing,and microstructure characterization is provided,followed by a summary of PDCs used in energy conversion systems(mainly in gas turbine engines),including fundamentals and material issues,ceramic matrix composites,ceramic fibers,thermal and environmental barrier coatings,as well as high-temperature sensors.Subsequently,applications of PDCs in the field of energy storage are reviewed with a strong focus on anode materials for lithium and sodium ion batteries.The possible applications of the PDCs in Li–S batteries,supercapacitors,and fuel cells are discussed as well.Finally,a summary of the reported applications and perspectives for future research with PDCs are presented.
基金The authors gratefully acknowledge computational time on the Lichtenberg High-Performance Supercomputer.Teng Long thanks the financial support from the China Scholarship Council(CSC).Part of this work was supported by the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(Grant No.743116-project Cool Innov)This work was also supported by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)–Project-ID 405553726–TRR 270We also acknowledge support by the Deutsche Forschungsgemeinschaft(DFG–German Research Foundation)and the Open Access Publishing Fund of Technical University of Darmstadt.
文摘Autonomous materials discovery with desired properties is one of the ultimate goals for materials science,and the current studies have been focusing mostly on high-throughput screening based on density functional theory calculations and forward modeling of physical properties using machine learning.Applying the deep learning techniques,we have developed a generative model,which can predict distinct stable crystal structures by optimizing the formation energy in the latent space.It is demonstrated that the optimization of physical properties can be integrated into the generative model as on-top screening or backward propagator,both with their own advantages.Applying the generative models on the binary Bi-Se system reveals that distinct crystal structures can be obtained covering the whole composition range,and the phases on the convex hull can be reproduced after the generated structures are fully relaxed to the equilibrium.The method can be extended to multicomponent systems for multi-objective optimization,which paves the way to achieve the inverse design of materials with optimal properties.
基金The support from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(grant agreement No 743116)German Research Foundation(DFG),the Profile Area From Material to Product Innovation-PMP and Open Access Publishing Fund of Technische Universität Darmstadt is acknowledged+1 种基金M.Y.acknowledges the support from the 15th Thousand Youth Talents Program of China,the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures(MCMS-I-0419G01)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘During selective laser sintering(SLS),the microstructure evolution and local temperature variation interact mutually.Application of conventional isothermal sintering model is thereby insufficient to describe SLS.In this work,we construct our model from entropy level,and derive the non-isothermal kinetics for order parameters along with the heat transfer equation coupled with microstructure evolution.Influences from partial melting and laser-powder interaction are also addressed.We then perform 3D finite element non-isothermal phase-field simulations of the SLS single scan.To confront the high computation cost,we propose a novel algorithm analogy to minimum coloring problem and manage to simulate a system of 200 grains with grain tracking algorithm using as low as 8 non-conserved order parameters.Specifically,applying the model to SLS of the stainless steel 316L powder,we identify the influences of laser power and scan speed on microstructural features,including the porosity,surface morphology,temperature profile,grain geometry,and densification.We further validate the first-order kinetics of the transient porosity during densification,and demonstrate the applicability of the developed model in predicting the linkage of densification factor to the specific energy input during SLS.
基金This work was supported by the European program“Eurostars”under the project number E!9765(Hybrid-3D)funded by the German partner with resources from the German Federal Ministry of Education and Research(BMBF).
文摘Microneedle-based microfluidic systems have a great potential to become well-accepted medical devices for simple,accurate,and painless drug delivery and lab-on-a-chip diagnostics.In this work,we report on a novel hybrid approach combining femtosecond direct laser written microneedles with femtosecond laser generated microfluidic channels providing an important step towards versatile medical point-of-care systems.Hollow microneedle arrays are fabricated by a laser system designed for two-photon polymerization applications.Compression tests of two different types of truncated cone-shaped microneedle arrays prepared from OrmoComp^(■)give information about the microneedle mechanical strength,and the results are compared to skin insertion forces.Three-dimensional microchannels are directly created inside PMMA bulk material by an ultrashort pulse laser system with vertical channels having adjustable cross-sectional areas,which allow attaching of microneedles to the microfluidic system.A comprehensive parameter study varying pulse duration and repetition rate is performed on two-photon polymerization to identify an optimal laser power range for fabricating microneedles using the same pulse duration and repetition rate as for microchannels.This addresses the advantage of a single laser system process that overcomes complex fabrication methods.A proof of concept flow test with a rhodamine B dye solution in distilled water demonstrates that the combination of microneedles and microchannels qualifies for microfluidic injection and extraction applications.
基金S.Flavel acknowledges support from the Deutsche Forschungsgemeinschafts Emmy Noether Program under grant number FL 834/1-1.
文摘Dielectrophoresis(DEP)describes the motion of suspended objects when exposed to an inhomogeneous electric field.It has been successful as a method for parallel and site-selective assembling of nanotubes from a dispersion into a sophisticated device architecture.Researchers have conducted extensive works to understand the DEP of nanotubes in aqueous ionic surfactant solutions.However,only recently,DEP was applied to polymer-wrapped single-walled carbon nanotubes(SWCNTs)in organic solvents due to the availability of ultra-pure SWCNT content.In this paper,the focus is on the difference between the DEP in aqueous and organic solutions.It starts with an introduction into the DEP of carbon nanotubes(CNT-DEP)to provide a comprehensive,in-depth theoretical background before discussing in detail the experimental procedures and conditions.For academic interests,this work focuses on the CNT-DEP deposition scheme,discusses the importance of the electrical double layer,and employs finite element simulations to optimize CNT-DEP deposition condition with respect to the experimental observation.An important outcome is an understanding of why DEP in organic solvents allows for the deposition and alignment of SWCNTs in low-frequency and even static electric fields,and why the response of semiconducting SWCNTs(s-SWCNTs)is strongly enhanced in non-conducting,weakly polarizable media.Strategies to further improve CNT-DEP for s-SWCNT-relevant applications are given as well.Overall,this work should serve as a practical guideline to select the appropriate setting for effective CNT DEPs.
基金The research was supported by the Bundesministerium für Bildung und Forschung(BMBF)within the project FESTBATT under Grant No.03XP0174AJ.R.and L.C.E.acknowledge support from the Deutsche Forschungsgemeinschaft(DFG,Grant no.RO 4542/4-1 and STU 611/5-1).
文摘Silica(SiO_(2))is an abundant material with a wide range of applications.Despite much progress,the atomistic modelling of the different forms of silica has remained a challenge.Here we show that by combining density-functional theory at the SCAN functional level with machine-learning-based interatomic potential fitting,a range of condensed phases of silica can be accurately described.We present a Gaussian approximation potential model that achieves high accuracy for the thermodynamic properties of the crystalline phases,and we compare its performance(and performance–cost trade-off)with that of multiple empirically fitted interatomic potentials for silica.We also include amorphous phases,assessing the ability of the potentials to describe structures of melt-quenched glassy silica,their energetic stability,and the high-pressure structural transition to a mainly sixfold-coordinated phase.We suggest that rather than standing on their own,machine-learned potentials for silica may be used in conjunction with suitable empirical models,each having a distinct role and complementing the other,by combining the advantages of the long simulation times afforded by empirical potentials and the near-quantum-mechanical accuracy of machine-learned potentials.This way,our work is expected to advance atomistic simulations of this key material and to benefit further computational studies in the field.
基金the DFG in the framework of the Excellence Initiative,Darmstadt Graduate School of Excellence Energy Science and Engineering(GSC 1070)the BMBF(05P19RDFA1)and the Hessian Ministry for Science and the Arts(HMWK)through the LOEWE Research Cluster Nuclear Photonics at TU Darmstadt.
文摘Targets with microstructured front surfaces have shown great potential in improving high-intensity laser–matter interaction.We present cone-shaped microstructures made out of silicon and titanium created by ultrashort laser pulse processing with different characteristics.In addition,we illustrate a process chain based on moulding to recreate the laser-processed samples out of polydimethylsiloxane,polystyrol and copper.With all described methods,samples of large sizes can be manufactured,therefore allowing time-efficient,cost-reduced and reliable ways to fabricate large quantities of identical targets.
基金supported by the National Natural Science Foundation of China(Nos.52002092,51832002,and 52172071)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(No.GZ2020012)+1 种基金Heilongjiang Natural Science Fund for Young Scholars(No.YQ2021E017)the Heilongjiang Touyan Innovation Team Program.Ralf Riedel thanks the German Science Foundation(DFG,Bonn,Germany)for financial support within the graduate school GRK 2561.
文摘The atomic structural features and the mechanical properties of amorphous silicoboron carbonitride ceramics with 13 different compositions in the Si–BN–C phase diagram are investigated employing ab-initio calculations.Both chemical bonds and local structures within the amorphous network relate to the elemental composition.The distribution of nine types of chemical bonds is composition-dependent,where the B–C,Si–N,Si–C,and B–N bonds hold a large proportion for all compositions.Si prefers to be tetrahedrally coordinated,while B and N prefer sp^(2)-like trigonal coordination.In the case of C,the tetrahedral coordination is predominant at relatively low C contents,while the trigonal coordination is found to be the main feature with the increasing C content.Such local structural characteristics greatly influence the mechanical properties of SiBCN ceramics.Among the studied amorphous ceramics,SiB_(2)C_(3)N_(2) and SiB_(3)C_(2)N_(3) with low Si contents and moderate C and/or BN contents have high elastic moduli,high tensile/shear strengths,and good debonding capability.The increment of Si,C,and BN contents on this basis results in the decrease of mechanical properties.The increasing Si content leads to the increment of Si-contained bonds that reduce the bond strength of SiBCN ceramics,while the latter two cases are attributed to the raise of sp^(2)-like trigonal configuration of C and BN.These discoveries are expected to guide the composition-tailored optimization of SiBCN ceramics.
