The paper considers a high-dimensional likelihood ratio(LR)test on the intraclass correlation structure of the multivariate normal population.When the dimension p and sample size N satisfy N−1>p→∞,it is proved th...The paper considers a high-dimensional likelihood ratio(LR)test on the intraclass correlation structure of the multivariate normal population.When the dimension p and sample size N satisfy N−1>p→∞,it is proved that the logarithmic LR statistic asymptotically obeys Gaussian distribution,and the explicit expressions of the mean and the variance are also obtained.The simulations demonstrate that our high-dimensional LR test method outperforms the traditional Chi-square approximation method or F-approximation method,and performs as efficient as the accurate high-dimensional Edgeworth expansion method and the more accurate high-dimensional Edgeworth expansion method in analyzing the intraclass covariance structure of highdimensional data.展开更多
Global positioning system(GPS)common-view observation data were processed by using the multi-scale Kalman algorithm based on a correlative structure of the discrete wavelet coefficients.Suppose that the GPS commonview...Global positioning system(GPS)common-view observation data were processed by using the multi-scale Kalman algorithm based on a correlative structure of the discrete wavelet coefficients.Suppose that the GPS commonview observation data has the 1/f fractal characteristic,the algorithm of wavelet transform was used to estimate the Hurst parameter H of GPS clock difference data.When 0<H<1,the 1/f fractal characteristic of the GPS clock difference data is a Gaussian zero-mean and non-stationary stochastic process.Thus,the discrete wavelet coefficients can be discussed in the process of estimating multi-scale Kalman coefficients.Furthermore,the discrete clock difference can be estimated.The single-channel and multi-channel common-view observation data were processed respectively.Comparisons were made between the results obtained and the Circular T data.Simulation results show that the algorithm discussed in this paper is both feasible and effective.展开更多
The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination n...The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination numbers are 0.312 um, 11.2 in solid state.10.932 nm, 10.932 in supercooled liquid region and 0.305 urn, 11.296 in liquid state. The structures are the same in different states. But it shows some tendency to crystallizing that the first coordination sphere radius and the first coordination number drop in supercooled liquid region.展开更多
The structure–dynamics correlations in a nonlocal manner were investigated in CuZr metallic glass-forming liquids via classical molecular dynamics simulations.A spatial coarse-graining approach was employed to incorp...The structure–dynamics correlations in a nonlocal manner were investigated in CuZr metallic glass-forming liquids via classical molecular dynamics simulations.A spatial coarse-graining approach was employed to incorporate the nonlocal structural information of given structural order parameters in the structure–dynamics relationship.It is found that the correlation between structure order parameters and dynamics increases with increasing coarse-graining length and has a characteristic length scale.Moreover,the characteristic correlation length exhibits a non-monotonic temperature evolution as temperature approaches glass transition temperature,which is not sensitive to the considered structure order parameters.Our results unveil a striking change in the structure–dynamics correlation,which involves no fitting theoretical interpretation.These findings provide new insight into the structure–dynamics correlation in glass transition.展开更多
We consider an entangled Ising-XY Z diamond chain structure. Quantum correlations for this model are inves- tigated by using quantum discord and trace distance discord. Quantum correlations are obtained for different ...We consider an entangled Ising-XY Z diamond chain structure. Quantum correlations for this model are inves- tigated by using quantum discord and trace distance discord. Quantum correlations are obtained for different values of the anisotropy parameter, magnetic field and temperature. By comparison between quantum correlations, we show that the trace distance discord is always larger than quantum discord. Finally, some novel effects such as increasing the quantum correlations with temperature and constructive role of anisotropy parameter, which may play to the quantum correlations, are observed.展开更多
In mass spectrometry, fragments with a mass higher than the original molecular ion provide valuable insights into the molecular structure and can guide the assembly and disassembly processes for chemical synthesis. He...In mass spectrometry, fragments with a mass higher than the original molecular ion provide valuable insights into the molecular structure and can guide the assembly and disassembly processes for chemical synthesis. Here, we report such an example and following up by modifying the solvothermal reaction conditions (temperature and time) it is possible to isolate the high mass species in crystalline form. [Zn_(4)L_(4)Cl_(4)] (Zn_(4)L_(4), L = N-methylbenzimidazole-2-methanolate) has a boat-like Zn_(4)O_(4) core but electrospray ionization mass spectrometry (ESI-MS) of the solution of its crystals shows higher mass peaks of Zn_(5)L_(5), Zn_(5)L_(6) and Zn_(6)L_(6) species. Thus, both disassembly and reassembly are highly probable processes. Consequently, [Zn(HL)_(2)Cl_(2)] (Zn1, L = N-methylbenzimidazole-2-methanolate), [Zn_(4)L_(6)Cl_(2)] (Zn_(4)L_(6), L = N-methylbenzimidazole-2-methanolate) and [Zn_(6)L_(6)Cl_(4)(CH_(3)O)_(2)] (Zn_(6)L_(6), L = N-methylbenzimidazole-2-methanolate) were prepared. The results of multistage ESI-MS of their dissolved crystals led to a proposed mechanism of their formation in the gas phase as follows: [Zn_(3)L_(4)] through [ZnL] → [ZnL(HL)] → [Zn(HL)_(2)] → [Zn_(2)L] → [Zn_(2)L_(2)] → [Zn_(2)L_(3)]. The mechanism was derived in conjunction with Gibbs free energies calculated using DFT of the fragments observed in the ESI-MS of Zn_(4)L_(4), Zn_(4)L_(6) and Zn_(6)L_(6). This work reveals the complex of chemical reactions, involving fragmentation and unexpected combination, under mass spectrometry condition which allows one to synthesize the observed transients, leading to mechanism of formation by correlation of solid-state/solution structural information.展开更多
The electrochemical reduction of CO_(2),as a renewable energy-driven electrochemical system,has emerged as an environmentally benign approach for producing valuable chemicals and fuels under mild reaction conditions.R...The electrochemical reduction of CO_(2),as a renewable energy-driven electrochemical system,has emerged as an environmentally benign approach for producing valuable chemicals and fuels under mild reaction conditions.Recent advances in the precise synthesis of metal nanoclusters,coupled with state-of-the-art characterization techniques,have enabled atomic-level investigation of structure-activity relationships in nanocatalysts.Due to their well-defined atomic architectures,the active metal sites within these nanocatalysts can be accurately identified,facilitating systematic studies on how compositions(structures)modulate catalytic performance.This review begins by summarizing recent advances in the controlled synthesis of atomically precise metal nanoclusters,followed by an overview of progress in the electrochemical reduction of CO_(2) to CO using nanoclusters as catalysts.Subsequently,we systematically investigate the effects of metal kernel characteristics and staple properties on catalytic activity,selectivity,and stability.Furthermore,current challenges are outlined,and prospective research directions are proposed in this rapidly evolving field.It is anticipated that this review will inspire further innovation in the synthesis of atomically precise nanocluster catalysts,promote a deeper mechanistic understanding of metal nanocluster-mediated electrochemical CO_(2) reduction,and push forward the related industrial applications.展开更多
In order to study the failure process of an anchorage structure and the evolution law of the body＇s defor- mation field, anchor push-out tests were carried out based on digital speckle correlation methods （DSCM）. T...In order to study the failure process of an anchorage structure and the evolution law of the body＇s defor- mation field, anchor push-out tests were carried out based on digital speckle correlation methods （DSCM）. The stress distribution of the anchorage interface was investigated using the particle flow numerical simulation method. The results indicate that there are three stages in the deformation and fail- ure process of an anchorage structure： elastic bonding stage, a de-bonding stage and a failure stage. The stress distribution in the interface controls the stability of the structure. In the elastic bonding stage, the shear stress peak point of the interface is close to the loading end, and the displacement field gradually develops into a ＂V＂ shape, in the de-bonding stage, there is a shear stress plateau in the center of the anchorage section, and shear strain localization begins to form in the deformation field. In the failure stage, the bonding of the interface fails rapidly and the shear stress peak point moves to the anchorage free end. The anchorage structure moves integrally along the macro-cracl~ The de-bonding stage is a research focus in the deformation and failure process of an anchorage structure, and plays an important guiding role in roadway support design and prediction of the stability of the surrounding rock.展开更多
This paper presents an incremental cutting method for evaluating the longitudinal residual stresses in a butt welded thin plate via combining the traditional residual stress measurement methods and the advanced optica...This paper presents an incremental cutting method for evaluating the longitudinal residual stresses in a butt welded thin plate via combining the traditional residual stress measurement methods and the advanced optical technique.The proposed approach,which can be called digital image correlation（DIC）-aided slitting technique,introduces a successive extension slot to a specimen and employs the DIC technique to measure the released displacement profiles of the cutting sections after each cutting increment.Then the displacement profiles are used to directly calculate the residual stress distributions up to the slot tip and hence,a stress distribution can be obtained after a cutting increment.Finally,all of the stress distributions are averaged to ultimately determine the original residual stress field.This method does not include any complex experimental operations or tedious derivation,and the resolution of stress variation is greatly improved by the continuous measurement of the released displacements.The presented method has been preliminarily verified by a specimen with residual stress introduced by a four-point bending test.The results show that residual stresses determined by the DIC-aided slitting technique agree well with those from finite element（FE） prediction.The residual stress in a friction stir welded aluminum specimen obtained by the presented technique is also consistent with the evaluations given by X-ray diffraction.Furthermore,the residual stresses obtained by the DIC-aided slitting technique demonstrate higher accuracy and stability than the evaluations derived by the DIC-aided contour method.展开更多
Dear Editor,This letter proposes the graph tensor alliance attention network(GT-A^(2)T)to represent a dynamic graph(DG)precisely.Its main idea includes 1)Establishing a unified spatio-temporal message propagation fram...Dear Editor,This letter proposes the graph tensor alliance attention network(GT-A^(2)T)to represent a dynamic graph(DG)precisely.Its main idea includes 1)Establishing a unified spatio-temporal message propagation framework on a DG via the tensor product for capturing the complex cohesive spatio-temporal interdependencies precisely and 2)Acquiring the alliance attention scores by node features and favorable high-order structural correlations.展开更多
Atomic arrangements and local sub-structures fundamentally influence emergent material functionalities.These structures are conventionally probed using spatially resolved studies and the property correlations are deci...Atomic arrangements and local sub-structures fundamentally influence emergent material functionalities.These structures are conventionally probed using spatially resolved studies and the property correlations are deciphered by a researcher based on sequential explorations,thereby limiting the efficiency and scope.Here we demonstrate a multi-scale Bayesian deep-learning based framework that automatically correlates material structure with its electronic properties using scanning tunneling microscopy(STM)measurements in real-time.Its predictions are used to autonomously direct exploration toward regions of the sample that optimize a given material property.This method is deployed on a low-temperature ultra-high vacuum STM to understand the structureproperty relationship in a europium-based semimetal,EuZn2As2,a promising candidate relevant to magnetism-driven topological phenomena.The framework employs a sparse-sampling approach to efficiently construct the scalar-property space using minimal measurements,about 1–10%of the data required in standard hyperspectral methods.Moreover,we formulate the problem hierarchically across length scales,implementing autonomous workflow to locate mesoscopic and atomic structures that correspond to a target material property.This framework offers the choice to design scalar-property from the spectroscopic data to steer sample exploration.Our findings reveal correlations of the electronic properties unique to surface terminations,local defect density,and point defects.展开更多
Over the past decade,considerable scientific attention has been given to adapting cobalt bis(dicarbollide)as innovative agent with various biomedical applications.Although the studied compounds show great potential in...Over the past decade,considerable scientific attention has been given to adapting cobalt bis(dicarbollide)as innovative agent with various biomedical applications.Although the studied compounds show great potential in this field,only a few reports have explored broad,well-thought-out libraries of derivatives to correlate their structure with biological activity.In this study,we investigate a panel of[CoSAN]^(−)derivatives substituted with fluorine,chlorine,bromine and iodine in order to elucidate the impact of the halogen presence on antimicrobial action and selectivity over mammalian cells.We present the first evidence that increasing the atomic mass of a substituent improves the biological activity of a derivative.Our results demonstrate that the addition of a single iodine atom to the[CoSAN]^(−)core results in the most selective antibacterial outcome,especially toward Staphylococcus aureus ATCC 6538.The described correlation between the lipophilicity and the activity of the compounds toward both bacteria and human cell lines highlights the importance of a conscious design method to obtain the most desirable[CoSAN]^(−)-based derivatives.展开更多
Classical survival analysis assumes all subjects will experience the event of interest, but in some cases, a portion of the population may never encounter the event. These survival methods further assume independent s...Classical survival analysis assumes all subjects will experience the event of interest, but in some cases, a portion of the population may never encounter the event. These survival methods further assume independent survival times, which is not valid for honey bees, which live in nests. The study introduces a semi-parametric marginal proportional hazards mixture cure (PHMC) model with exchangeable correlation structure, using generalized estimating equations for survival data analysis. The model was tested on clustered right-censored bees survival data with a cured fraction, where two bee species were subjected to different entomopathogens to test the effect of the entomopathogens on the survival of the bee species. The Expectation-Solution algorithm is used to estimate the parameters. The study notes a weak positive association between cure statuses (ρ1=0.0007) and survival times for uncured bees (ρ2=0.0890), emphasizing their importance. The odds of being uncured for A. mellifera is higher than the odds for species M. ferruginea. The bee species, A. mellifera are more susceptible to entomopathogens icipe 7, icipe 20, and icipe 69. The Cox-Snell residuals show that the proposed semiparametric PH model generally fits the data well as compared to model that assume independent correlation structure. Thus, the semi parametric marginal proportional hazards mixture cure is parsimonious model for correlated bees survival data.展开更多
Interpretative structural model(ISM) can transform a multivariate problem into several sub-variable problems to analyze a complex industrial structure in a more efficient way by building a multi-level hierarchical str...Interpretative structural model(ISM) can transform a multivariate problem into several sub-variable problems to analyze a complex industrial structure in a more efficient way by building a multi-level hierarchical structure model. To build an ISM of a production system, the partial correlation coefficient method is proposed to obtain the adjacency matrix, which can be transformed to ISM. According to estimation of correlation coefficient, the result can give actual variable correlations and eliminate effects of intermediate variables. Furthermore, this paper proposes an effective approach using ISM to analyze the main factors and basic mechanisms that affect the energy consumption in an ethylene production system. The case study shows that the proposed energy consumption analysis method is valid and efficient in improvement of energy efficiency in ethylene production.展开更多
A retention prediction system(RPS)of seven O-ethyl N-isopropyl phosphoro(thioureido)- thioates in reversed phase HPLC was investigated.The system is based on the solvent selectivity triangle concept.Three molecular st...A retention prediction system(RPS)of seven O-ethyl N-isopropyl phosphoro(thioureido)- thioates in reversed phase HPLC was investigated.The system is based on the solvent selectivity triangle concept.Three molecular structure parameters(hydrophobicity Ⅱ,substituent length L, and substituent maximum width B_5)were used to describe the quantitative structure-retention relation- ships.With these quantitative relationships,the retention behaviours of other eight homologs for different mobile phase composition were predicted.The predicted values were consistent with the measured values within relative error of 10%,which means that it is possible to apply the reported method to predict retention values for qualitative purposes for different mobile phase compositions.展开更多
Changes in structure of oral solid dosage forms(OSDF)elementally determine the drug release and its therapeutic effects.In this research,synchrotron radiation X-ray micro-computed tomography was utilized to visualize ...Changes in structure of oral solid dosage forms(OSDF)elementally determine the drug release and its therapeutic effects.In this research,synchrotron radiation X-ray micro-computed tomography was utilized to visualize the 3 D structure of enteric coated pellets recovered from the gastrointestinal tract of rats.The structures of pellets in solid state and in vitro compendium media were measured.Pellets in vivo underwent morphological and structural changes which differed significantly from those in vitro compendium media.Thus,optimizations of the dissolution media were performed to mimic the appropriate in vivo conditions by introducing pepsin and glass microspheres in media.The sphericity,pellet volume,pore volume and porosity of the in vivo esomeprazole magnesium pellets in stomach for2 h were recorded 0.47,1.55×10^(8)μm^(3),0.44×10^(8)μm^(3)and 27.6%,respectively.After adding pepsin and glass microspheres,the above parameters in vitro reached to 0.44,1.64×10^(8)μm^(3)0.38×10^(8)μm^(3)and 23.0%,respectively.Omeprazole magnesium pellets behaved similarly.The structural features of pellets between in vitro media and in vivo condition were bridged successfully in terms of 3 D structures to ensure better design,characterization and quality control of advanced OSDF.展开更多
Single-molecule magnets(SMMs)are promising candidates as components for the next generation of molecule-based electronics.As the state-of-the-art in this field is mainly focused on heavy lanthanide(III)(Ln^(III))ions,...Single-molecule magnets(SMMs)are promising candidates as components for the next generation of molecule-based electronics.As the state-of-the-art in this field is mainly focused on heavy lanthanide(III)(Ln^(III))ions,examples of light lanthanide-based systems,e.g.,those based on Nd^(III),have fallen far behind.Besides the slow relaxation of magnetisation,the luminescence of multifunctional Ln^(III) complexes can be leveraged for in situ temperature monitoring via luminescence thermometry.To help understand how both magnetic and luminescence performance can be improved through structural modifications in Nd^(III)-based SMMs,two dinuclear Nd^(III) complexes,[Nd^(III)_(2)(valdien)_(2)(X)_(2)](X=acac-{1-Nd_(2)}or NO_(3)-{2-Nd_(2)}),are herein reported,and we discuss opto-and magneto-structural correlations depending on the terminal ligand.The Nd^(III) complexes display field-induced slow relaxation of magnetization,but for{2-Nd_(2)},QTM has a lower contribution because the longer Nd^(III)-Oterminal distances induce a weaker equatorial crystal field component.The systems were further used to develop luminescent temperature probes featuring a maximum thermal sensitivity of 0.52%K-1 at 40 K for{2-Nd_(2)},confirming its multifunctional slow relaxation of magnetisation and temperature readout features.展开更多
Layered tin chalcogenide frameworks (LTCFs) have attracted great attention due to the stable structure and effective integration of porosity with semiconducting properties.Though they have a much suitable band gap and...Layered tin chalcogenide frameworks (LTCFs) have attracted great attention due to the stable structure and effective integration of porosity with semiconducting properties.Though they have a much suitable band gap and rich structures,the significance of LTCFs in photoelectrochemical applications and “structure-property” studies is highly undervalued.Herein,we report an example of “structure-property” correlations in photoelectrochemical applications using three subtly regulated LTCFs that show nuances in the intralayer architecture and packing mode of layers.Of particular interest is the huge difference in their photoelectric responses despite the same secondary building block (Sn_(3)S_(4)),linkers (shared Sn_(2)S_(2)) and 2D honeycomb-type topology.In particular,LTCF-3 has the highest photocurrent density,which is nearly five times that of LTCF-2.Enhanced photoelectric response for LTCF-3 was attributed to the elongated distance between adjacent clusters,which dramatically decreased the recombination of photo-induced carriers.This deduction was supported by precise structure analysis,UV-vis absorption spectroscopy and theoretical calculations.展开更多
Thiolate-protected gold nanoclusters(RS-AuNCs)have emerged as an ideal research system for unveiling intrinsic structure–property correlations due to their atomically precise structural tunability.This study addresse...Thiolate-protected gold nanoclusters(RS-AuNCs)have emerged as an ideal research system for unveiling intrinsic structure–property correlations due to their atomically precise structural tunability.This study addresses the structural absence and configuration stability controversies of face-centered cubic(FCC)-configured RS-AuNCs in the large-size regime of 102–191 gold atoms by establishing an innovative theoretical analysis framework.Through density functional theory(DFT)calculations,we successfully predicted for the first time a twinned-FCC Au127(SR)48 structure with C_(2) symmetry(Au127-x),which exhibits a remarkably small energy difference of merely 0.03 eV compared to the lowest-energy Dh configuration(Au127-w).This discovery strongly confirms the thermodynamic feasibility of FCC configurations in the 102-144 atom range.By integrating the‘kernel-differentiated fusion’growth mechanism with the‘divideand-protected’assembly strategy,we systematically constructed three large-sized FCC cluster models:Au164(SR)60,Au_(182)(SR)_(66) and Au_(188)(SR)_(66).The calculated average formation energies(Eave)validate the exceptional structural stability of these clusters.Strikingly divergent evolution patterns in HOMO–LUMO gaps are observed between shell-structured and cubic FCC-type RS-AuNCs across varying sizes,unambiguously demonstrating configuration-governed electronic structure modulation.More crucially,UV-Vis absorption spectra unveil emergent metallic signatures in both Au_(182)(SR)_(66) and Au_(188)(SR)_(66) clusters,thereby fundamentally redefining the critical size threshold for incipient metallicity in FCC-type RS-AuNCs.Breaking through traditional theoretical frameworks centered on‘size-configuration preference’,this research first elucidates the potential stability of FCC-configured RS-AuNCs within controversial size ranges.It not only addresses the existing size gap in structural models of large RS-AuNCs but also establishes a novel configuration design paradigm based on a‘kernel-differentiated fusion’strategy.展开更多
Classical Mach-number(M) scaling in compressible wall turbulence was suggested by van Driest(Van Driest E R.Turbulent boundary layers in compressible fluids.J Aerodynamics Science,1951,18(3):145-160) and Huang et al.(...Classical Mach-number(M) scaling in compressible wall turbulence was suggested by van Driest(Van Driest E R.Turbulent boundary layers in compressible fluids.J Aerodynamics Science,1951,18(3):145-160) and Huang et al.(Huang P G,Coleman G N,Bradshaw P.Compressible turbulent channel flows:DNS results and modeling.J Fluid Mech,1995,305:185-218).Using a concept of velocity-vorticity correlation structure(VVCS),defined by high correlation regions in a field of two-point cross-correlation coefficient between a velocity and a vorticity component,we have discovered a limiting VVCS as the closest streamwise vortex structure to the wall,which provides a concrete Morkovin scaling summarizing all compressibility effects.Specifically,when the height and mean velocity of the limiting VVCS are used as the units for the length scale and the velocity,all geometrical measures in the spanwise and normal directions,as well as the mean velocity and fluctuation(r.m.s) profiles become M-independent.The results are validated by direct numerical simulations(DNS) of compressible channel flows with M up to 3.Furthermore,a quantitative model is found for the M-scaling in terms of the wall density,which is also validated by the DNS data.These findings yield a geometrical interpretation of the semi-local transformation(Huang et al.,1995),and a conclusion that the location and the thermodynamic properties associated with the limiting VVCS determine the M-effects on supersonic wall-bounded flows.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.11401169)Natural Science Foundation of Henan Province of China(Grant No.202300410089).
文摘The paper considers a high-dimensional likelihood ratio(LR)test on the intraclass correlation structure of the multivariate normal population.When the dimension p and sample size N satisfy N−1>p→∞,it is proved that the logarithmic LR statistic asymptotically obeys Gaussian distribution,and the explicit expressions of the mean and the variance are also obtained.The simulations demonstrate that our high-dimensional LR test method outperforms the traditional Chi-square approximation method or F-approximation method,and performs as efficient as the accurate high-dimensional Edgeworth expansion method and the more accurate high-dimensional Edgeworth expansion method in analyzing the intraclass covariance structure of highdimensional data.
基金supported by the National Natural Science Foundation of China (Grant No.60571060).
文摘Global positioning system(GPS)common-view observation data were processed by using the multi-scale Kalman algorithm based on a correlative structure of the discrete wavelet coefficients.Suppose that the GPS commonview observation data has the 1/f fractal characteristic,the algorithm of wavelet transform was used to estimate the Hurst parameter H of GPS clock difference data.When 0<H<1,the 1/f fractal characteristic of the GPS clock difference data is a Gaussian zero-mean and non-stationary stochastic process.Thus,the discrete wavelet coefficients can be discussed in the process of estimating multi-scale Kalman coefficients.Furthermore,the discrete clock difference can be estimated.The single-channel and multi-channel common-view observation data were processed respectively.Comparisons were made between the results obtained and the Circular T data.Simulation results show that the algorithm discussed in this paper is both feasible and effective.
文摘The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination numbers are 0.312 um, 11.2 in solid state.10.932 nm, 10.932 in supercooled liquid region and 0.305 urn, 11.296 in liquid state. The structures are the same in different states. But it shows some tendency to crystallizing that the first coordination sphere radius and the first coordination number drop in supercooled liquid region.
基金the National Natural Science Foundation of China(Grant Nos.52031016 and 51631003)。
文摘The structure–dynamics correlations in a nonlocal manner were investigated in CuZr metallic glass-forming liquids via classical molecular dynamics simulations.A spatial coarse-graining approach was employed to incorporate the nonlocal structural information of given structural order parameters in the structure–dynamics relationship.It is found that the correlation between structure order parameters and dynamics increases with increasing coarse-graining length and has a characteristic length scale.Moreover,the characteristic correlation length exhibits a non-monotonic temperature evolution as temperature approaches glass transition temperature,which is not sensitive to the considered structure order parameters.Our results unveil a striking change in the structure–dynamics correlation,which involves no fitting theoretical interpretation.These findings provide new insight into the structure–dynamics correlation in glass transition.
基金Supported by the Azerbaijan Shahid Madani University
文摘We consider an entangled Ising-XY Z diamond chain structure. Quantum correlations for this model are inves- tigated by using quantum discord and trace distance discord. Quantum correlations are obtained for different values of the anisotropy parameter, magnetic field and temperature. By comparison between quantum correlations, we show that the trace distance discord is always larger than quantum discord. Finally, some novel effects such as increasing the quantum correlations with temperature and constructive role of anisotropy parameter, which may play to the quantum correlations, are observed.
基金supported by the BAGUI Talent Program in Guangxi Province(No.2019AC26001),and the National Natural Science Foundation of China(No.22171075,U23A2080).
文摘In mass spectrometry, fragments with a mass higher than the original molecular ion provide valuable insights into the molecular structure and can guide the assembly and disassembly processes for chemical synthesis. Here, we report such an example and following up by modifying the solvothermal reaction conditions (temperature and time) it is possible to isolate the high mass species in crystalline form. [Zn_(4)L_(4)Cl_(4)] (Zn_(4)L_(4), L = N-methylbenzimidazole-2-methanolate) has a boat-like Zn_(4)O_(4) core but electrospray ionization mass spectrometry (ESI-MS) of the solution of its crystals shows higher mass peaks of Zn_(5)L_(5), Zn_(5)L_(6) and Zn_(6)L_(6) species. Thus, both disassembly and reassembly are highly probable processes. Consequently, [Zn(HL)_(2)Cl_(2)] (Zn1, L = N-methylbenzimidazole-2-methanolate), [Zn_(4)L_(6)Cl_(2)] (Zn_(4)L_(6), L = N-methylbenzimidazole-2-methanolate) and [Zn_(6)L_(6)Cl_(4)(CH_(3)O)_(2)] (Zn_(6)L_(6), L = N-methylbenzimidazole-2-methanolate) were prepared. The results of multistage ESI-MS of their dissolved crystals led to a proposed mechanism of their formation in the gas phase as follows: [Zn_(3)L_(4)] through [ZnL] → [ZnL(HL)] → [Zn(HL)_(2)] → [Zn_(2)L] → [Zn_(2)L_(2)] → [Zn_(2)L_(3)]. The mechanism was derived in conjunction with Gibbs free energies calculated using DFT of the fragments observed in the ESI-MS of Zn_(4)L_(4), Zn_(4)L_(6) and Zn_(6)L_(6). This work reveals the complex of chemical reactions, involving fragmentation and unexpected combination, under mass spectrometry condition which allows one to synthesize the observed transients, leading to mechanism of formation by correlation of solid-state/solution structural information.
基金supported financially by the following:Natural Science Foundation of China,Grant Numbers:21829501,21925303,22471275,21771186,22075291,21222301,21171170,21528303,U24A20480,92475105,22503108CASHIPS Director’s Fund(BJPY2019A02)+6 种基金the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(2020HSC-CIP005)the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(2022HSC-CIP018)Presidential Foundation of HFIPS of Chinese Academy of Sciences(no.YZJJ2023QN28)the HFIPS Director’s Fund(no.YZJJ-GGZX-2022-01)the CAS/SAFEA International Partner-ship Program for Creative Research Teamsthe Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(Grant Number:GZC20241744)Hefei Institute of Physical Science,Chinese Academy of Sciences(BR-E44BGGBR12B).
文摘The electrochemical reduction of CO_(2),as a renewable energy-driven electrochemical system,has emerged as an environmentally benign approach for producing valuable chemicals and fuels under mild reaction conditions.Recent advances in the precise synthesis of metal nanoclusters,coupled with state-of-the-art characterization techniques,have enabled atomic-level investigation of structure-activity relationships in nanocatalysts.Due to their well-defined atomic architectures,the active metal sites within these nanocatalysts can be accurately identified,facilitating systematic studies on how compositions(structures)modulate catalytic performance.This review begins by summarizing recent advances in the controlled synthesis of atomically precise metal nanoclusters,followed by an overview of progress in the electrochemical reduction of CO_(2) to CO using nanoclusters as catalysts.Subsequently,we systematically investigate the effects of metal kernel characteristics and staple properties on catalytic activity,selectivity,and stability.Furthermore,current challenges are outlined,and prospective research directions are proposed in this rapidly evolving field.It is anticipated that this review will inspire further innovation in the synthesis of atomically precise nanocluster catalysts,promote a deeper mechanistic understanding of metal nanocluster-mediated electrochemical CO_(2) reduction,and push forward the related industrial applications.
基金financially supported by the National Key Basic Research Program of China (No.2010CB226805)the National Natural Science Foundation of China (Nos.51474136 and 51474013)+1 种基金the Opening Project Fund of State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology (No.MDPC2013KF06)the Research Award Fund for the Excellent Youth of Shandong University of Science and Technology (No.2011KYJQ106)
文摘In order to study the failure process of an anchorage structure and the evolution law of the body＇s defor- mation field, anchor push-out tests were carried out based on digital speckle correlation methods （DSCM）. The stress distribution of the anchorage interface was investigated using the particle flow numerical simulation method. The results indicate that there are three stages in the deformation and fail- ure process of an anchorage structure： elastic bonding stage, a de-bonding stage and a failure stage. The stress distribution in the interface controls the stability of the structure. In the elastic bonding stage, the shear stress peak point of the interface is close to the loading end, and the displacement field gradually develops into a ＂V＂ shape, in the de-bonding stage, there is a shear stress plateau in the center of the anchorage section, and shear strain localization begins to form in the deformation field. In the failure stage, the bonding of the interface fails rapidly and the shear stress peak point moves to the anchorage free end. The anchorage structure moves integrally along the macro-cracl~ The de-bonding stage is a research focus in the deformation and failure process of an anchorage structure, and plays an important guiding role in roadway support design and prediction of the stability of the surrounding rock.
基金supported by the National Natural Science Foundation of China(No.11272029)
文摘This paper presents an incremental cutting method for evaluating the longitudinal residual stresses in a butt welded thin plate via combining the traditional residual stress measurement methods and the advanced optical technique.The proposed approach,which can be called digital image correlation（DIC）-aided slitting technique,introduces a successive extension slot to a specimen and employs the DIC technique to measure the released displacement profiles of the cutting sections after each cutting increment.Then the displacement profiles are used to directly calculate the residual stress distributions up to the slot tip and hence,a stress distribution can be obtained after a cutting increment.Finally,all of the stress distributions are averaged to ultimately determine the original residual stress field.This method does not include any complex experimental operations or tedious derivation,and the resolution of stress variation is greatly improved by the continuous measurement of the released displacements.The presented method has been preliminarily verified by a specimen with residual stress introduced by a four-point bending test.The results show that residual stresses determined by the DIC-aided slitting technique agree well with those from finite element（FE） prediction.The residual stress in a friction stir welded aluminum specimen obtained by the presented technique is also consistent with the evaluations given by X-ray diffraction.Furthermore,the residual stresses obtained by the DIC-aided slitting technique demonstrate higher accuracy and stability than the evaluations derived by the DIC-aided contour method.
基金supported in part by the National Natural Science Foundation of China(62372385).
文摘Dear Editor,This letter proposes the graph tensor alliance attention network(GT-A^(2)T)to represent a dynamic graph(DG)precisely.Its main idea includes 1)Establishing a unified spatio-temporal message propagation framework on a DG via the tensor product for capturing the complex cohesive spatio-temporal interdependencies precisely and 2)Acquiring the alliance attention scores by node features and favorable high-order structural correlations.
基金supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratorysupported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, MLExchange Project, award number 107514. GN acknowledges Dr. Yongtao Liu for helping with the DKL code execution.
文摘Atomic arrangements and local sub-structures fundamentally influence emergent material functionalities.These structures are conventionally probed using spatially resolved studies and the property correlations are deciphered by a researcher based on sequential explorations,thereby limiting the efficiency and scope.Here we demonstrate a multi-scale Bayesian deep-learning based framework that automatically correlates material structure with its electronic properties using scanning tunneling microscopy(STM)measurements in real-time.Its predictions are used to autonomously direct exploration toward regions of the sample that optimize a given material property.This method is deployed on a low-temperature ultra-high vacuum STM to understand the structureproperty relationship in a europium-based semimetal,EuZn2As2,a promising candidate relevant to magnetism-driven topological phenomena.The framework employs a sparse-sampling approach to efficiently construct the scalar-property space using minimal measurements,about 1–10%of the data required in standard hyperspectral methods.Moreover,we formulate the problem hierarchically across length scales,implementing autonomous workflow to locate mesoscopic and atomic structures that correspond to a target material property.This framework offers the choice to design scalar-property from the spectroscopic data to steer sample exploration.Our findings reveal correlations of the electronic properties unique to surface terminations,local defect density,and point defects.
文摘Over the past decade,considerable scientific attention has been given to adapting cobalt bis(dicarbollide)as innovative agent with various biomedical applications.Although the studied compounds show great potential in this field,only a few reports have explored broad,well-thought-out libraries of derivatives to correlate their structure with biological activity.In this study,we investigate a panel of[CoSAN]^(−)derivatives substituted with fluorine,chlorine,bromine and iodine in order to elucidate the impact of the halogen presence on antimicrobial action and selectivity over mammalian cells.We present the first evidence that increasing the atomic mass of a substituent improves the biological activity of a derivative.Our results demonstrate that the addition of a single iodine atom to the[CoSAN]^(−)core results in the most selective antibacterial outcome,especially toward Staphylococcus aureus ATCC 6538.The described correlation between the lipophilicity and the activity of the compounds toward both bacteria and human cell lines highlights the importance of a conscious design method to obtain the most desirable[CoSAN]^(−)-based derivatives.
文摘Classical survival analysis assumes all subjects will experience the event of interest, but in some cases, a portion of the population may never encounter the event. These survival methods further assume independent survival times, which is not valid for honey bees, which live in nests. The study introduces a semi-parametric marginal proportional hazards mixture cure (PHMC) model with exchangeable correlation structure, using generalized estimating equations for survival data analysis. The model was tested on clustered right-censored bees survival data with a cured fraction, where two bee species were subjected to different entomopathogens to test the effect of the entomopathogens on the survival of the bee species. The Expectation-Solution algorithm is used to estimate the parameters. The study notes a weak positive association between cure statuses (ρ1=0.0007) and survival times for uncured bees (ρ2=0.0890), emphasizing their importance. The odds of being uncured for A. mellifera is higher than the odds for species M. ferruginea. The bee species, A. mellifera are more susceptible to entomopathogens icipe 7, icipe 20, and icipe 69. The Cox-Snell residuals show that the proposed semiparametric PH model generally fits the data well as compared to model that assume independent correlation structure. Thus, the semi parametric marginal proportional hazards mixture cure is parsimonious model for correlated bees survival data.
基金Supported by the National Natural Science Foundation of China(61374166,6153303)the Doctoral Fund of Ministry of Education of China(20120010110010)the Fundamental Research Funds for the Central Universities(YS1404,JD1413,ZY1502)
文摘Interpretative structural model(ISM) can transform a multivariate problem into several sub-variable problems to analyze a complex industrial structure in a more efficient way by building a multi-level hierarchical structure model. To build an ISM of a production system, the partial correlation coefficient method is proposed to obtain the adjacency matrix, which can be transformed to ISM. According to estimation of correlation coefficient, the result can give actual variable correlations and eliminate effects of intermediate variables. Furthermore, this paper proposes an effective approach using ISM to analyze the main factors and basic mechanisms that affect the energy consumption in an ethylene production system. The case study shows that the proposed energy consumption analysis method is valid and efficient in improvement of energy efficiency in ethylene production.
文摘A retention prediction system(RPS)of seven O-ethyl N-isopropyl phosphoro(thioureido)- thioates in reversed phase HPLC was investigated.The system is based on the solvent selectivity triangle concept.Three molecular structure parameters(hydrophobicity Ⅱ,substituent length L, and substituent maximum width B_5)were used to describe the quantitative structure-retention relation- ships.With these quantitative relationships,the retention behaviours of other eight homologs for different mobile phase composition were predicted.The predicted values were consistent with the measured values within relative error of 10%,which means that it is possible to apply the reported method to predict retention values for qualitative purposes for different mobile phase compositions.
基金financial support from National Key R&D Program of China(2020YFE0201700)Major New Drugs Innovation and Development(2017ZX09101001-005,China)+1 种基金the National Natural Science Foundation of China(81803441,81803446 and 81773645)Youth Innovation Promotion Association CAS(2018323,China)。
文摘Changes in structure of oral solid dosage forms(OSDF)elementally determine the drug release and its therapeutic effects.In this research,synchrotron radiation X-ray micro-computed tomography was utilized to visualize the 3 D structure of enteric coated pellets recovered from the gastrointestinal tract of rats.The structures of pellets in solid state and in vitro compendium media were measured.Pellets in vivo underwent morphological and structural changes which differed significantly from those in vitro compendium media.Thus,optimizations of the dissolution media were performed to mimic the appropriate in vivo conditions by introducing pepsin and glass microspheres in media.The sphericity,pellet volume,pore volume and porosity of the in vivo esomeprazole magnesium pellets in stomach for2 h were recorded 0.47,1.55×10^(8)μm^(3),0.44×10^(8)μm^(3)and 27.6%,respectively.After adding pepsin and glass microspheres,the above parameters in vitro reached to 0.44,1.64×10^(8)μm^(3)0.38×10^(8)μm^(3)and 23.0%,respectively.Omeprazole magnesium pellets behaved similarly.The structural features of pellets between in vitro media and in vivo condition were bridged successfully in terms of 3 D structures to ensure better design,characterization and quality control of advanced OSDF.
基金financial support provided by the University of Ottawa,the Canadian Foundation for Innovation(CFI),and the Natural Sciences and Engineering Research Council of Canada(NSERC)A.G.B.J.acknowledges the São Paulo Research Foundation FAPESP(Grant No.2021/09755-0 and 2019/23763-6)+2 种基金F.A.S.acknowledges FAPESP:2021/06326-1 and 2021/08111-2,INCT/INOMAT-National Institute of Science Technology in Complex Functional Materials(CNPq:465452/2014-0 and FAPESP:50906-9/2014)FAPESP:2012/11382-9,and CNPq 306107/2019-8Claudia Calado Dias is acknowledged for powder XRD measurements and Alexandros A.Kitos for useful discussions.
文摘Single-molecule magnets(SMMs)are promising candidates as components for the next generation of molecule-based electronics.As the state-of-the-art in this field is mainly focused on heavy lanthanide(III)(Ln^(III))ions,examples of light lanthanide-based systems,e.g.,those based on Nd^(III),have fallen far behind.Besides the slow relaxation of magnetisation,the luminescence of multifunctional Ln^(III) complexes can be leveraged for in situ temperature monitoring via luminescence thermometry.To help understand how both magnetic and luminescence performance can be improved through structural modifications in Nd^(III)-based SMMs,two dinuclear Nd^(III) complexes,[Nd^(III)_(2)(valdien)_(2)(X)_(2)](X=acac-{1-Nd_(2)}or NO_(3)-{2-Nd_(2)}),are herein reported,and we discuss opto-and magneto-structural correlations depending on the terminal ligand.The Nd^(III) complexes display field-induced slow relaxation of magnetization,but for{2-Nd_(2)},QTM has a lower contribution because the longer Nd^(III)-Oterminal distances induce a weaker equatorial crystal field component.The systems were further used to develop luminescent temperature probes featuring a maximum thermal sensitivity of 0.52%K-1 at 40 K for{2-Nd_(2)},confirming its multifunctional slow relaxation of magnetisation and temperature readout features.
基金financial support from National Natural Science Foundation of China(22201117)Shandong Province Natural Science Foundation(ZR2022QB003)+1 种基金Doctoral Program of Liaocheng University(No.318052049)Jiangsu Specially Appointed Professorship and the startup funding from Nanjing Normal University,and the Development Project of Youth Innovation Team in Shandong Colleges and Universities(2019KJC031).
文摘Layered tin chalcogenide frameworks (LTCFs) have attracted great attention due to the stable structure and effective integration of porosity with semiconducting properties.Though they have a much suitable band gap and rich structures,the significance of LTCFs in photoelectrochemical applications and “structure-property” studies is highly undervalued.Herein,we report an example of “structure-property” correlations in photoelectrochemical applications using three subtly regulated LTCFs that show nuances in the intralayer architecture and packing mode of layers.Of particular interest is the huge difference in their photoelectric responses despite the same secondary building block (Sn_(3)S_(4)),linkers (shared Sn_(2)S_(2)) and 2D honeycomb-type topology.In particular,LTCF-3 has the highest photocurrent density,which is nearly five times that of LTCF-2.Enhanced photoelectric response for LTCF-3 was attributed to the elongated distance between adjacent clusters,which dramatically decreased the recombination of photo-induced carriers.This deduction was supported by precise structure analysis,UV-vis absorption spectroscopy and theoretical calculations.
基金the financial support from the National Natural Science Foundation of China(Grant No.22203053)the Natural Science Foundation of Hunan Province(Grant No.2023JJ40606)+1 种基金Y.P.was financially supported by the National Natural Science Foundation of China(Grant No.22373082)the science and technology innovation program of Hunan Province(2023RC1055).
文摘Thiolate-protected gold nanoclusters(RS-AuNCs)have emerged as an ideal research system for unveiling intrinsic structure–property correlations due to their atomically precise structural tunability.This study addresses the structural absence and configuration stability controversies of face-centered cubic(FCC)-configured RS-AuNCs in the large-size regime of 102–191 gold atoms by establishing an innovative theoretical analysis framework.Through density functional theory(DFT)calculations,we successfully predicted for the first time a twinned-FCC Au127(SR)48 structure with C_(2) symmetry(Au127-x),which exhibits a remarkably small energy difference of merely 0.03 eV compared to the lowest-energy Dh configuration(Au127-w).This discovery strongly confirms the thermodynamic feasibility of FCC configurations in the 102-144 atom range.By integrating the‘kernel-differentiated fusion’growth mechanism with the‘divideand-protected’assembly strategy,we systematically constructed three large-sized FCC cluster models:Au164(SR)60,Au_(182)(SR)_(66) and Au_(188)(SR)_(66).The calculated average formation energies(Eave)validate the exceptional structural stability of these clusters.Strikingly divergent evolution patterns in HOMO–LUMO gaps are observed between shell-structured and cubic FCC-type RS-AuNCs across varying sizes,unambiguously demonstrating configuration-governed electronic structure modulation.More crucially,UV-Vis absorption spectra unveil emergent metallic signatures in both Au_(182)(SR)_(66) and Au_(188)(SR)_(66) clusters,thereby fundamentally redefining the critical size threshold for incipient metallicity in FCC-type RS-AuNCs.Breaking through traditional theoretical frameworks centered on‘size-configuration preference’,this research first elucidates the potential stability of FCC-configured RS-AuNCs within controversial size ranges.It not only addresses the existing size gap in structural models of large RS-AuNCs but also establishes a novel configuration design paradigm based on a‘kernel-differentiated fusion’strategy.
基金supported by the National Nature Science Foundation of China (Grant Nos.90716008,10572004 and 11172006)the National Basic Research Program of China (Grant No.2009CB724100)
文摘Classical Mach-number(M) scaling in compressible wall turbulence was suggested by van Driest(Van Driest E R.Turbulent boundary layers in compressible fluids.J Aerodynamics Science,1951,18(3):145-160) and Huang et al.(Huang P G,Coleman G N,Bradshaw P.Compressible turbulent channel flows:DNS results and modeling.J Fluid Mech,1995,305:185-218).Using a concept of velocity-vorticity correlation structure(VVCS),defined by high correlation regions in a field of two-point cross-correlation coefficient between a velocity and a vorticity component,we have discovered a limiting VVCS as the closest streamwise vortex structure to the wall,which provides a concrete Morkovin scaling summarizing all compressibility effects.Specifically,when the height and mean velocity of the limiting VVCS are used as the units for the length scale and the velocity,all geometrical measures in the spanwise and normal directions,as well as the mean velocity and fluctuation(r.m.s) profiles become M-independent.The results are validated by direct numerical simulations(DNS) of compressible channel flows with M up to 3.Furthermore,a quantitative model is found for the M-scaling in terms of the wall density,which is also validated by the DNS data.These findings yield a geometrical interpretation of the semi-local transformation(Huang et al.,1995),and a conclusion that the location and the thermodynamic properties associated with the limiting VVCS determine the M-effects on supersonic wall-bounded flows.
