The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorp...The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorption temperature,adsorption time and adsorbent dosage on their adsorptive denitrification performance were systematically investigated.The experimental results demonstrated that under a fixed adsorbent dosage of 0.05 g and a simulated fuel volume of 10 mL,the optimal removal efficiency for aniline was achieved at 30℃ within 30 min,whereas higher temperatures and longer times(40℃and 40 min)were required for effective removal of pyridine and quinoline.Density Functional Theory(DFT)calculations were conducted via Materials Studio(MS)software to study the adsorptive denitrification mechanism of MIL-101(Cr)toward these three basic nitrogen-containing compounds.The simulation calculation results revealed that the interaction between pyridine and MIL-101(Cr)primarily involved coordination adsorption.In contrast,the interaction between aniline or quinoline and MIL-101(Cr)proceeded mainly through coordination,with additional contributions fromπ-complexation and hydrogen bonding.The overall adsorption strength order is pyridine>aniline>quinoline.During the adsorption process,pyridine and quinoline transfer electrons to the MIL-101(Cr)surface through the H→C→N→Cr^(3+)pathway,while aniline transfers electrons to the MIL-101(Cr)surface through various pathways,including N→Cr^(3+),N→C→Cr^(3+)and N→H→O.Furthermore,adsorption kinetics studies indicated that the adsorption processes for all three basic nitrogen-containing compounds followed the quasi second order kinetic models.The experimental results on the effect of benzene on the adsorptive denitrification performance of MIL-101(Cr)-0.5 demonstrated that benzene exerted a more significant impact on the adsorption of aniline and quinoline.Finally,the adsorbent was regenerated using ethanol washing.It was found that MIL-101(Cr)-0.5 retained stable denitrification performance after two regeneration cycles.展开更多
The stress minimization multi-material topology optimization(MMTO)approach has recently attracted significant attention because of its applications in aerospace and mechanical engineering.Nonetheless,the stress minimi...The stress minimization multi-material topology optimization(MMTO)approach has recently attracted significant attention because of its applications in aerospace and mechanical engineering.Nonetheless,the stress minimization MMTO approach may result in stress surpassing the material's tolerance limit,potentially culminating in failure.This research proposes a novel way for imposing stress constraints on each material to regulate their respective stress levels.The fundamental concept is that each material possesses its own interpolation function for the stress model.The maximum von Mises stress for each material can be established with the definition of an upper limit,ensuring that the materials will perform safely and effectively.This aids topological structures in resisting failure and augmenting strength.A multi-physics system including thermoelastic and self-weight loads is concurrently examined alongside stress limitations.The global stress constraint utilizes the p-norm function,and the adjoint method is used to derive sensitivity.This work employs a three-field strategy utilizing density filtering and Heaviside projection functions to mitigate the artificial stress in low density.The technique is assessed through two-dimensional(2D)and three-dimensional(3D)examples,illustrating the influence of stress limits on the compliance minimization under heat and self-weight loads.The optimized results indicate a substantial decrease in the stress levels accompanied by a minor gain in compliance,while maintaining the stress within the specified range for all materials.展开更多
The electric double layer(EDL)at the electrochemical interface is crucial for ion transport,charge transfer,and surface reactions in aqueous rechargeable zinc batteries(ARZBs).However,Zn anodes routinely encounter per...The electric double layer(EDL)at the electrochemical interface is crucial for ion transport,charge transfer,and surface reactions in aqueous rechargeable zinc batteries(ARZBs).However,Zn anodes routinely encounter persistent dendrite growth and parasitic reactions,driven by the inhomogeneous charge distribution and water-dominated environment within the EDL.Compounding this,classical EDL theory,rooted in meanfield approximations,further fails to resolve molecular-scale interfacial dynamics under battery-operating conditions,limiting mechanistic insights.Herein,we established a multiscale theoretical calculation framework from single molecular characteristics to interfacial ion distribution,revealing the EDL’s structure and interactions between different ions and molecules,which helps us understand the parasitic processes in depth.Simulations demonstrate that water dipole and sulfate ion adsorption at the inner Helmholtz plane drives severe hydrogen evolution and by-product formation.Guided by these insights,we engineered a“water-poor and anion-expelled”EDL using 4,1’,6’-trichlorogalactosucrose(TGS)as an electrolyte additive.As a result,Zn||Zn symmetric cells with TGS exhibited stable cycling for over 4700 h under a current density of 1 mA cm^(−2),while NaV_(3)O_(8)·1.5H_(2)O-based full cells kept 90.4%of the initial specific capacity after 800 cycles at 5 A g^(−1).This work highlights the power of multiscale theoretical frameworks to unravel EDL complexities and guide high-performance ARZB design through integrated theory-experiment approaches.展开更多
Underwater gas-liquid two-phase propulsion technology is an emerging propulsion method that offers high efficiency and unrestricted navigation speed.The integration of this technology into water ramjet engines can sig...Underwater gas-liquid two-phase propulsion technology is an emerging propulsion method that offers high efficiency and unrestricted navigation speed.The integration of this technology into water ramjet engines can significantly enhance propulsion efficiency and holds substantial potential for broad applications.However,forming a gas-liquid two-phase flow within the nozzle requires introducing a large amount of rammed seawater.At this time,there is a complex phase transition problem of combustion products in the combustion chamber,which makes the thermodynamic calculation for gas-liquid two-phase water ramjet engines particularly challenging.This paper proposes a thermodynamic calculation method for gas-liquid two-phase water ramjet engines,based on the energy equation for gas-liquid two-phase flow and traditional thermodynamic principles,enabling thermodynamic calculations under conditions of ultra-high water-fuel ratios.Additionally,ground ignition tests of the gas-liquid two-phase engine were conducted,yielding critical engine test parameters.The results demonstrate that the gas-liquid two-phase water ramjet engine achieves a high specific impulse,with a theoretical maximum specific impulse of up to 7000(N s)/kg.The multiphase flow effects significantly impact engine performance,with specific impulse losses reaching up to 25.86%.The error between the thrust and specific impulse in the ground test and the theoretical values is within 10%,validating the proposed thermodynamic calculation method as a reliable reference for further research on gas-liquid two-phase water ramjet engines.展开更多
As cataract surgery progresses from “restoration of sight” to “refractive correction”, precise prediction of intraocular lens (IOL) power is critical for enhancing postoperative visual quality in patients. IOL pow...As cataract surgery progresses from “restoration of sight” to “refractive correction”, precise prediction of intraocular lens (IOL) power is critical for enhancing postoperative visual quality in patients. IOL power calculation methods have evolved and innovated throughout time, from early theoretical and regression formulas to nonlinear formulas for estimating effective lens position (ELP), multivariable formulas, and innovative formulas that use optical principles and AI-based online formulas. This paper thoroughly discusses the development and iteration of traditional IOL calculation formulas, the emergence of new IOL calculation formulas, and the selection of IOL calculation formulas for different patients in the era of refractive cataract surgery, serving as a reference for “personalized” IOL implantation in clinical practice.展开更多
Soft robots, inspired by the flexibility and versatility of biological organisms, have potential in a variety of applications. Recent advancements in magneto-soft robots have demonstrated their abilities to achieve pr...Soft robots, inspired by the flexibility and versatility of biological organisms, have potential in a variety of applications. Recent advancements in magneto-soft robots have demonstrated their abilities to achieve precise remote control through magnetic fields, enabling multi-modal locomotion and complex manipulation tasks. Nonetheless, two main hurdles must be overcome to advance the field: developing a multi-component substrate with embedded magnetic particles to ensure the requisite flexibility and responsiveness, and devising a cost-effective,straightforward method to program three-dimensional distributed magnetic domains without complex processing and expensive machinery. Here, we introduce a cost-effective and simple heat-assisted in-situ integrated molding fabrication method for creating magnetically driven soft robots with three-dimensional programmable magnetic domains. By synthesizing a composite material with neodymium-iron-boron(NdFeB) particles embedded in a polydimethylsiloxane(PDMS) and Ecoflex matrix(PDMS:Ecoflex = 1:2 mass ratio, 50% magnetic particle concentration), we achieved an optimized balance of flexibility, strength, and magnetic responsiveness. The proposed heat-assisted in-situ magnetic domains programming technique,performed at an experimentally optimized temperature of 120℃, resulted in a 2 times magnetization strength(9.5 mT) compared to that at 20℃(4.8 m T), reaching a saturation level comparable to a commercial magnetizer. We demonstrated the versatility of our approach through the fabrication of six kinds of robots, including two kinds of two-dimensional patterned soft robots(2D-PSR), a circular six-pole domain distribution magnetic robot(2D-CSPDMR), a quadrupedal walking magnetic soft robot(QWMSR), an object manipulation robot(OMR), and a hollow thin-walled spherical magneto-soft robot(HTWSMSR). The proposed method provides a practical solution to create highly responsive and adaptable magneto-soft robots.展开更多
Multi-material 3D sand printing has gained significant attention;however,research has mainly focused on materials and mechanisms,with limited exploration of optimizing the sand-laying process through numerical simulat...Multi-material 3D sand printing has gained significant attention;however,research has mainly focused on materials and mechanisms,with limited exploration of optimizing the sand-laying process through numerical simulations.In this study,we investigated the dynamic behavior of sand particles during a vibratory sand-laying process for multi-material additive manufacturing using discrete element simulations.The objective is to enable precise control over the amount and distribution of sand for multi-material printing.In this study,we combined experiments and simulations to calibrate the contact parameters of different sands and establish a relationship between the curing agent content and surface energy of sand particles.A model for the vibratory fall of multimaterial sand was developed to study the motion characteristics of sand particles.This allows for macro-control over the sand spreading flow and high-quality multi-material sand laying.The results show that the flow rate of falling sand increases with decreasing surface energy of the particles,wider spreader openings,and higher vibration frequencies.For silica and chromite sands,when their surface energy ranged from 0.15 to 25 J·m^(2)and0.01-0.03 J·m^(2),respectively,and the sand spreader opening was 6 mm with a vibration frequency of 500 Hz,the sand flow rates of both materials became nearly identical.However,a higher sand paving speed and height increased the scattering of sand particles outside the target area,thereby decreasing the paving quality.The results accomplished in this study enable precise and uniform sand particle deposition and offers guidelines for optimizing sand speed and height,thus expanding the application of multi-material sand 3D printing in complex and high-performance manufacturing.展开更多
The application of multi-material topology optimization affords greater design flexibility compared to traditional single-material methods.However,density-based topology optimization methods encounter three unique cha...The application of multi-material topology optimization affords greater design flexibility compared to traditional single-material methods.However,density-based topology optimization methods encounter three unique challenges when inertial loads become dominant:non-monotonous behavior of the objective function,possible unconstrained characterization of the optimal solution,and parasitic effects.Herein,an improved Guide-Weight approach is introduced,which effectively addresses the structural topology optimization problem when subjected to inertial loads.Smooth and fast convergence of the compliance is achieved by the approach,while also maintaining the effectiveness of the volume constraints.The rational approximation of material properties model and smooth design are utilized to guarantee clear boundaries of the final structure,facilitating its seamless integration into manufacturing processes.The framework provided by the alternating active-phase algorithm is employed to decompose the multi-material topological problem under inertial loading into a set of sub-problems.The optimization of multi-material under inertial loads is accomplished through the effective resolution of these sub-problems using the improved Guide-Weight method.The effectiveness of the proposed approach is demonstrated through numerical examples involving two-phase and multi-phase materials.展开更多
The effects of pressure on the structural stability,elasticity,electronic properties,and thermodynamic properties of Al,Al_(3)Cu,Al_(2)Cu,Al_(4)Cu_(9),AlCu_(3),and Cu were investigated using first-principles calculati...The effects of pressure on the structural stability,elasticity,electronic properties,and thermodynamic properties of Al,Al_(3)Cu,Al_(2)Cu,Al_(4)Cu_(9),AlCu_(3),and Cu were investigated using first-principles calculations.The experimental results indicate that the calculated equilibrium lattice constant,elastic constant,and elastic modulus agree with both theoretical and experimental data at 0 GPa.The Young's modulus,bulk modulus,and shear modulus increase with increasing pressure.The influence of pressure on mechanical properties is explained from a chemical bond perspective.By employing the quasi-harmonic approximation model of phonon calculation,the temperature and pressure dependence of thermodynamic parameters in the range of 0 to 800 K and 0 to 100 GPa are determined.The findings demonstrate that the thermal capacity and coefficient of thermal expansion increase with increasing temperature and decrease with increasing pressure.This study provides fundamental data and support for experimental investigations and further theoretical research on the properties of aluminum-copper intermetallic compounds.展开更多
The vacuum reactive wetting and brazing of Er_(2)Si_(2)O_(7)/MoSi_(2) coatings were investigated using a (CoFeNiCrMn)_(88)Nb_(12) high-entropy alloy (HEA) brazing filler. The microstructural evolution and wettability ...The vacuum reactive wetting and brazing of Er_(2)Si_(2)O_(7)/MoSi_(2) coatings were investigated using a (CoFeNiCrMn)_(88)Nb_(12) high-entropy alloy (HEA) brazing filler. The microstructural evolution and wettability of the HEA filler were analyzed, with particular attention to the surface energy, interfacial stability, and electronic properties of the HEA filler/rare earth silicate coating system, as determined by density functional theory (DFT). As Nb diffused into the interface and the ErNbO_(4) phase formed, the wetting angle gradually decreased to 23.12° The effective wetting and spreading of the HEA brazing filler on the rare earth silicate coating surface are strongly correlated with the formation of the ErNbO_(4) phase at the interface. Furthermore, DFT calculations reveal that the interfacial bonding energy between the BCC' and FCC' phases and the ErNbO_(4) phase, after the wetting reaction, is significantly higher than the bonding energy between the initial filler and Er_(2)Si_(2)O_(7). This finding suggests that the formation of the ErNbO_(4) phase improves the wetting and spreading behavior of the filler.展开更多
Control of hyperfine interaction strength of shallow donors in Si is one of the central issues in realizing Kane quantum computers.First-principles calculations on the hyperfine Stark shift of shallow donors are chall...Control of hyperfine interaction strength of shallow donors in Si is one of the central issues in realizing Kane quantum computers.First-principles calculations on the hyperfine Stark shift of shallow donors are challenging since large supercells are needed to accommodate the delocalized donor wave functions.In this work,we investigated the hyperfine Stark shift and its strain tunability for shallow donors P and As in Si using the potential patching method based on first-principles density functional theory calculations.The good agreement between our calculations and experimental results confirms that the potential patching method is a feasible and accurate first-principles approach for studying wave-function-related properties of shallow impurities,such as the Stark shift parameter.It is further shown that the application of strain expands the range of hyperfine Stark shift and helps improve the response of shallow donor based qubit gates.The results could be useful for developing quantum computing architectures based on shallow donors in Si.展开更多
Steel-concrete composite beams,due to their superior mechanical properties,are widely utilized in engineering structures.This study systematically investigates the calculation methods for internal forces and load-bear...Steel-concrete composite beams,due to their superior mechanical properties,are widely utilized in engineering structures.This study systematically investigates the calculation methods for internal forces and load-bearing capacity of composite beams based on elastic theory,with a focus on the transformed section method and its application under varying neutral axis positions.By deriving the geometric characteristics of the transformed section and incorporating a reduction factor accounting for slip effects,a computational model for sectional stress and ultimate load-bearing capacity is established.The results demonstrate that the slip effect significantly influences the flexural load-bearing capacity of composite beams.The proposed reduction factor,which considers the influence of the steel beam’s top flange thickness,offers higher accuracy compared to traditional methods.These findings provide a theoretical foundation for the design and analysis of composite beams,with significant practical engineering value.展开更多
Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium ...Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium montmorillonite(Na-MMT)(001)surfaces was investigated using first-principles calculations in this study,especially As atom and H_(3)AsO_(3) molecule.The adsorption energies of the As atom were−1.94 eV on the illite(001)and−0.56 eV on the Na-MMT(001),whereas,the adsorption energies of the H_(3)AsO_(3) molecule were−1.40 eV on illite(001)and−1.01 eV on Na-MMT(001).The above results indicate that the adsorption was more energetically favorable on illite(001).Additionally,compared to Na-MMT(001),there were more significant interactions between the atoms/molecules on the illite(001).After As atom and H_(3)AsO_(3) molecule adsorption,the electrons were transferred from mineral surface atoms to the adsorbates on both illite(001)and Na-MMT(001)surfaces.Moreover,the adsorption of As atom on illite(001)and Na-MMT(001)surfaces were more energy favorable compared to Hg,Cd,and Cr atoms.Overall,this work provides new insights into the adsorption behavior of As atoms and As molecules on illite and Na-MMT.The results indicate that illite rich soils are more prone to contamination by arsenic compared to soils primarily composed of Na-MMT minerals.展开更多
The longitudinal cracks distributed along the dam axis in the corridor of a dam may have potential safety hazards.According to the detection results of crack depth and width and the analysis of monitoring data,a three...The longitudinal cracks distributed along the dam axis in the corridor of a dam may have potential safety hazards.According to the detection results of crack depth and width and the analysis of monitoring data,a three-dimensional finite element model is established for numerical simulation calculation and the influence of cracks on the safety of dam structure is analyzed from different aspects such as deformation,stress value,and distribution range.The calculation results show that the maximum principal tensile stress value and the location of the dam body are basically independent of the change of crack depth(within 1.0 m).Regarding local stress around the corridor,the high upstream water level causes cracks to deepen,resulting in an increase in the maximum tensile stress near the crack tip and an expansion of the tensile stress region.展开更多
AIM:To investigate the effect of pharmacological pupil alterations on intraocular lens(IOL)power calculations.METHODS:A systematic review and Meta-analysis of studies published before December 2023 in the PubMed,Embas...AIM:To investigate the effect of pharmacological pupil alterations on intraocular lens(IOL)power calculations.METHODS:A systematic review and Meta-analysis of studies published before December 2023 in the PubMed,Embase,and Cochrane library databases on the accuracy of pharmacological pupil changes on IOL power calculation was performed.The primary outcome was the results of IOL power calculations before and after the use of medications.Subgroup analyses were performed based on participants’basic characteristics,such as age,axial length(AL),and whether miosis or mydriasis were used as classification criteria for further analyses.Each eligible study was evaluated for potential risk of bias by the AHRQ assessment scale.The study was registered on PROSPERO(CRD 42024497535).RESULTS:A total of 3062 eyes from 21 studies were eligible.There was no significant difference in the IOL power calculation before and after pharmacological pupil changes using any of the Hoffer Q(WMD=0.055,95%CI=-0.046–0.156;P=0.29),SRK/T(WMD=0.003,95%CI=-0.073–0.080;P=0.93),Haigis(WMD=-0.030,95%CI=-0.176–0.116;P=0.69),Holladay 2(WMD=-0.042,95%CI=-0.366–0.282;P=0.80),and Barrett Universal Ⅱ(WMD=0.033,95%CI=-0.061–0.127;P=0.49)formulas.On the measurement of parameters related to IOL power calculation,for either miosis or mydriasis AL(P=0.98 and 0.29,respectively),lens thickness(P=0.96 and 0.13,respectively),and mean keratometry(P=0.90 and 0.86,respectively)did not present significant differences,while anterior chamber depth(P=0.07 and<0.01,respectively)and white-to-white distance(P=0.01 and 0.04,respectively)changed significantly between the two measurements prior and posterior.At the same time,despite there being some participants with the difference between the before and after calculations greater than 0.5 diopter,there was no significant difference in the incidence rate between these formulas.CONCLUSION:There is no significant effect of pharmacological pupil changes on the IOL power calculation.It will considerably reduce the visit time burden for patients who require cataract surgery.展开更多
The micro-area characterization experiments like scanning Kelvin probe force microscope(SKPFM)and Kernel average misorientation have the defects of complex sample preparation and occasional errors in test results,whic...The micro-area characterization experiments like scanning Kelvin probe force microscope(SKPFM)and Kernel average misorientation have the defects of complex sample preparation and occasional errors in test results,which makes it impossible to accurately and quickly analyze the pitting behavior induced by inclusions in some cases,prompting attempts to turn to simulation calculation research.The method of calculating band structure and work function can be used to replace current-sensing atomic force microscopy and SKPFM to detect the potential and conductivity of the sample.The band structure results show that Al_(2)O_(3) inclusion is an insulator and non-conductive,and it will not form galvanic corrosion with the matrix.Al_(2)O_(3) inclusion does not dissolve because its work function is higher than that of the matrix.Moreover,the stress concentration of the matrix around the inclusion can be characterized by first-principles calculation coupled with finite element simulation.The results show that the stress concentration degree of the matrix around Al_(2)O_(3) inclusion is serious,and the galvanic corrosion is formed between the high and the low stress concentration areas,which can be used to explain the reason of the pitting induced by Al_(2)O_(3) inclusions.展开更多
In this study,6061 aluminum alloy and galvanized steel fusion-brazed lap joints were obtained using a laser-arc hybrid heat source,and the effects of laser power variation on the microstructure,mechanical properties,a...In this study,6061 aluminum alloy and galvanized steel fusion-brazed lap joints were obtained using a laser-arc hybrid heat source,and the effects of laser power variation on the microstructure,mechanical properties,and fracture mechanism of the joints were ana-lyzed.The results showed that the tensile shear load initially increased with rising laser power,followed by a decrease.At a laser power of 240 W,the maximum tensile shear load was 2479.8 N/cm and the weak section of joint was in the Al-Fe reaction layer con-sisting of Fe(Al,Si)_(3),Fe_(2)(Al,Si)_(5),and Fe(Al,Si)intermetallic compounds(IMCs).Computational results showed that the inherently high brittleness and hardness of Fe(Al,Si)_(3) and the high mismatch rates of Fe(Al,Si)_(3)/Al interfaces were the key factor leading to the failure of the joints at lower heat input.展开更多
Neutron-rich boron,carbon,and nitrogen isotopes have garnered extensive experimental and theoretical interest.In the present work,we conducted a comprehensive study of these nuclei by utilizing ab initio valence-space...Neutron-rich boron,carbon,and nitrogen isotopes have garnered extensive experimental and theoretical interest.In the present work,we conducted a comprehensive study of these nuclei by utilizing ab initio valence-space in-medium similarity renormalization group calculations with chiral nucleon-nucleon and three-nucleon interactions.First,we systematically calculated the spectra of nuclei.Our results align well with the available experimental data,which are comparable to phenomenological shell model calculations.Subsequently,the evolution of the N=14 and N=16 shell gaps is discussed based on the calculated spectra and the effective single-particle energies.Our calculations suggest that the N=14 neutron subshell is present in the oxygen isotopes but disappears in the boron,carbon,and nitrogen isotopic chains.Moreover,the N=16 subshell is present in all isotopes but gradually decreases from^(24)O to^(21)B.These results provide valuable information for future studies.展开更多
Ni-Mn-Ti Heusler alloys have great potential for elastocaloric refrigeration due to the colossal caloric effect and good mechanical properties. However, theoretical calculations on the characterization of the elastoca...Ni-Mn-Ti Heusler alloys have great potential for elastocaloric refrigeration due to the colossal caloric effect and good mechanical properties. However, theoretical calculations on the characterization of the elastocaloric effect are rare. An important parameter to evaluate the elastocaloric effect is the transformation entropy change, whose main source is the vibrational entropy change (ΔS_(vib)). Unfortunately, the widely used quasiharmonic approximation method fails in the prediction of the vibrational entropy for high-temperature austenite due to its dynamical instability at 0 K. To solve this problem, the temperature dependent effective potential method was used considering the temperature and anharmonic effect. Sc, V, and Zr doping at the Ti sites in B2 disordered Ni_(8)Mn_(5)Ti_(3) were studied about phase stability, martensitic transformation, and elastocaloric properties. The results revealed the austenitic structures of all the doping systems exhibit antiferromagnetic coupling characteristics at 300 K due to the temperature effect. Sc and Zr doping at the Ti sites decreased the ΔS_(vib) value, whereas V doping at the Ti site increased the ΔS_(vib) value. Further analysis proved the important evaluation criterion that the ΔS_(vib) value increases with the tetragonal distortion ratio and volume change, which has important guiding significance for improving the elastocaloric effect. Besides, the calculations of elastic constants presented all the doping systems maintain outstanding ductility evaluated from the B/G ratio. This work provides an effective strategy for designing excellent elastocaloric material with large vibrational entropy change and good mechanical properties.展开更多
Two pairs of novel 6/6/6/9 tetracyclic merosesquiterpenoid enantiomers,dauroxonanols A(1)and B(2),possessing an unprecedented 9,15-dioxatetracyclo[8.5.3.0^(4.17).0^(14.18)]octadecane core skeleton,were isolated from R...Two pairs of novel 6/6/6/9 tetracyclic merosesquiterpenoid enantiomers,dauroxonanols A(1)and B(2),possessing an unprecedented 9,15-dioxatetracyclo[8.5.3.0^(4.17).0^(14.18)]octadecane core skeleton,were isolated from Rhododendron dauricum.The nuclear magnetic resonance(NMR)spectra of 1 and 2 showed very broad resonances,and^(13)C NMR spectrum of 1 exhibited only 13 instead of 22 carbon resonances.These broadening or missing NMR resonances led to a great challenge to elucidate their structures using NMR data analysis.Their structures and absolute configurations of 1 and 2 were finally determined by single crystal X-ray diffraction analysis,chiral separation,and electronic circular dichroism(ECD)calculations.Plausible biosynthetic pathways for 1 and 2 are proposed.Conformational analysis,density functional theory(DFT)calculations,and dynamic NMR assigned the coalescent NMR phenomena of 1 and 2 to the conformational changes of the flexible oxonane ring.Dauroxonanols A(1)and B(2)showed potentα-glucosidase inhibitory activities,2-8 times potent than acarbose,an antidiabetic drug targetingα-glucosidase in clinic.展开更多
基金Supported by Basic Scientific Research Project of the Liaoning Provincial Department of Education Has Been Unveiled to Facilitate Local Project Funding (JYTMS20230835)Enhanced Scientific Research Project Funded by the Departmentof Higher Education in Liaoning Province (General program)(JYTMS20230852)。
文摘The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorption temperature,adsorption time and adsorbent dosage on their adsorptive denitrification performance were systematically investigated.The experimental results demonstrated that under a fixed adsorbent dosage of 0.05 g and a simulated fuel volume of 10 mL,the optimal removal efficiency for aniline was achieved at 30℃ within 30 min,whereas higher temperatures and longer times(40℃and 40 min)were required for effective removal of pyridine and quinoline.Density Functional Theory(DFT)calculations were conducted via Materials Studio(MS)software to study the adsorptive denitrification mechanism of MIL-101(Cr)toward these three basic nitrogen-containing compounds.The simulation calculation results revealed that the interaction between pyridine and MIL-101(Cr)primarily involved coordination adsorption.In contrast,the interaction between aniline or quinoline and MIL-101(Cr)proceeded mainly through coordination,with additional contributions fromπ-complexation and hydrogen bonding.The overall adsorption strength order is pyridine>aniline>quinoline.During the adsorption process,pyridine and quinoline transfer electrons to the MIL-101(Cr)surface through the H→C→N→Cr^(3+)pathway,while aniline transfers electrons to the MIL-101(Cr)surface through various pathways,including N→Cr^(3+),N→C→Cr^(3+)and N→H→O.Furthermore,adsorption kinetics studies indicated that the adsorption processes for all three basic nitrogen-containing compounds followed the quasi second order kinetic models.The experimental results on the effect of benzene on the adsorptive denitrification performance of MIL-101(Cr)-0.5 demonstrated that benzene exerted a more significant impact on the adsorption of aniline and quinoline.Finally,the adsorbent was regenerated using ethanol washing.It was found that MIL-101(Cr)-0.5 retained stable denitrification performance after two regeneration cycles.
基金Project supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2025-02303676)。
文摘The stress minimization multi-material topology optimization(MMTO)approach has recently attracted significant attention because of its applications in aerospace and mechanical engineering.Nonetheless,the stress minimization MMTO approach may result in stress surpassing the material's tolerance limit,potentially culminating in failure.This research proposes a novel way for imposing stress constraints on each material to regulate their respective stress levels.The fundamental concept is that each material possesses its own interpolation function for the stress model.The maximum von Mises stress for each material can be established with the definition of an upper limit,ensuring that the materials will perform safely and effectively.This aids topological structures in resisting failure and augmenting strength.A multi-physics system including thermoelastic and self-weight loads is concurrently examined alongside stress limitations.The global stress constraint utilizes the p-norm function,and the adjoint method is used to derive sensitivity.This work employs a three-field strategy utilizing density filtering and Heaviside projection functions to mitigate the artificial stress in low density.The technique is assessed through two-dimensional(2D)and three-dimensional(3D)examples,illustrating the influence of stress limits on the compliance minimization under heat and self-weight loads.The optimized results indicate a substantial decrease in the stress levels accompanied by a minor gain in compliance,while maintaining the stress within the specified range for all materials.
基金supported by the National Natural Science Foundation of China(52471240)the Natural Science Foundation of Zhejiang Province(LZ23B030003)+2 种基金the Fundamental Research Funds for the Central Universities(226-2024-00075)support from the Engineering and Physical Sciences Research Council(EPSRC,UK)RiR grant-RIR18221018-1EU COST CA23155。
文摘The electric double layer(EDL)at the electrochemical interface is crucial for ion transport,charge transfer,and surface reactions in aqueous rechargeable zinc batteries(ARZBs).However,Zn anodes routinely encounter persistent dendrite growth and parasitic reactions,driven by the inhomogeneous charge distribution and water-dominated environment within the EDL.Compounding this,classical EDL theory,rooted in meanfield approximations,further fails to resolve molecular-scale interfacial dynamics under battery-operating conditions,limiting mechanistic insights.Herein,we established a multiscale theoretical calculation framework from single molecular characteristics to interfacial ion distribution,revealing the EDL’s structure and interactions between different ions and molecules,which helps us understand the parasitic processes in depth.Simulations demonstrate that water dipole and sulfate ion adsorption at the inner Helmholtz plane drives severe hydrogen evolution and by-product formation.Guided by these insights,we engineered a“water-poor and anion-expelled”EDL using 4,1’,6’-trichlorogalactosucrose(TGS)as an electrolyte additive.As a result,Zn||Zn symmetric cells with TGS exhibited stable cycling for over 4700 h under a current density of 1 mA cm^(−2),while NaV_(3)O_(8)·1.5H_(2)O-based full cells kept 90.4%of the initial specific capacity after 800 cycles at 5 A g^(−1).This work highlights the power of multiscale theoretical frameworks to unravel EDL complexities and guide high-performance ARZB design through integrated theory-experiment approaches.
基金supported by the Stable Support Fund forBasic Disciplines,China(No.3072024WD0201)。
文摘Underwater gas-liquid two-phase propulsion technology is an emerging propulsion method that offers high efficiency and unrestricted navigation speed.The integration of this technology into water ramjet engines can significantly enhance propulsion efficiency and holds substantial potential for broad applications.However,forming a gas-liquid two-phase flow within the nozzle requires introducing a large amount of rammed seawater.At this time,there is a complex phase transition problem of combustion products in the combustion chamber,which makes the thermodynamic calculation for gas-liquid two-phase water ramjet engines particularly challenging.This paper proposes a thermodynamic calculation method for gas-liquid two-phase water ramjet engines,based on the energy equation for gas-liquid two-phase flow and traditional thermodynamic principles,enabling thermodynamic calculations under conditions of ultra-high water-fuel ratios.Additionally,ground ignition tests of the gas-liquid two-phase engine were conducted,yielding critical engine test parameters.The results demonstrate that the gas-liquid two-phase water ramjet engine achieves a high specific impulse,with a theoretical maximum specific impulse of up to 7000(N s)/kg.The multiphase flow effects significantly impact engine performance,with specific impulse losses reaching up to 25.86%.The error between the thrust and specific impulse in the ground test and the theoretical values is within 10%,validating the proposed thermodynamic calculation method as a reliable reference for further research on gas-liquid two-phase water ramjet engines.
文摘As cataract surgery progresses from “restoration of sight” to “refractive correction”, precise prediction of intraocular lens (IOL) power is critical for enhancing postoperative visual quality in patients. IOL power calculation methods have evolved and innovated throughout time, from early theoretical and regression formulas to nonlinear formulas for estimating effective lens position (ELP), multivariable formulas, and innovative formulas that use optical principles and AI-based online formulas. This paper thoroughly discusses the development and iteration of traditional IOL calculation formulas, the emergence of new IOL calculation formulas, and the selection of IOL calculation formulas for different patients in the era of refractive cataract surgery, serving as a reference for “personalized” IOL implantation in clinical practice.
基金supported by National Natural Science Foundation of China(Grant Nos.62473277,62473275,62133004,52105072,and 62073230)Jiangsu Provincial Outstanding Youth Program(Grant No.BK20230072)+5 种基金National Key R&D Program of China(Grant Nos.2022YFC3802302 and 2023YFB4705600)Suzhou Industrial Foresight and Key Core Technology Project(Grant No.SYC2022044)Zhejiang Provincial Natural Science Foundation of China(Grant No.LZ24E050004)Shenzhen Polytechnic High-level Talent Start-up Project(Grant No.6023330006K)Shenzhen Science and Technology Program(Grant No.JCYJ20210324132810026)a Grant from Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems,Grants from Jiangsu QingLan Project and Jiangsu 333 high-level talents.
文摘Soft robots, inspired by the flexibility and versatility of biological organisms, have potential in a variety of applications. Recent advancements in magneto-soft robots have demonstrated their abilities to achieve precise remote control through magnetic fields, enabling multi-modal locomotion and complex manipulation tasks. Nonetheless, two main hurdles must be overcome to advance the field: developing a multi-component substrate with embedded magnetic particles to ensure the requisite flexibility and responsiveness, and devising a cost-effective,straightforward method to program three-dimensional distributed magnetic domains without complex processing and expensive machinery. Here, we introduce a cost-effective and simple heat-assisted in-situ integrated molding fabrication method for creating magnetically driven soft robots with three-dimensional programmable magnetic domains. By synthesizing a composite material with neodymium-iron-boron(NdFeB) particles embedded in a polydimethylsiloxane(PDMS) and Ecoflex matrix(PDMS:Ecoflex = 1:2 mass ratio, 50% magnetic particle concentration), we achieved an optimized balance of flexibility, strength, and magnetic responsiveness. The proposed heat-assisted in-situ magnetic domains programming technique,performed at an experimentally optimized temperature of 120℃, resulted in a 2 times magnetization strength(9.5 mT) compared to that at 20℃(4.8 m T), reaching a saturation level comparable to a commercial magnetizer. We demonstrated the versatility of our approach through the fabrication of six kinds of robots, including two kinds of two-dimensional patterned soft robots(2D-PSR), a circular six-pole domain distribution magnetic robot(2D-CSPDMR), a quadrupedal walking magnetic soft robot(QWMSR), an object manipulation robot(OMR), and a hollow thin-walled spherical magneto-soft robot(HTWSMSR). The proposed method provides a practical solution to create highly responsive and adaptable magneto-soft robots.
基金supported by the Jiangsu Provincial Basic Research Program(Natural Science Foundation)Youth Fund(Grant No.BK20230885)the International Joint Laboratory of Sustainable Manufacturing,Ministry of Education and Fundamental Research Funds for Central Universities(Grant No.NG2024012)Major Project on Fundamental Research of Aero-Engines and Gas Turbines,Ministry of Industry and Information Technology Special Project on High-Quality Development(Grant No.J2022-Ⅶ-0006-0048)。
文摘Multi-material 3D sand printing has gained significant attention;however,research has mainly focused on materials and mechanisms,with limited exploration of optimizing the sand-laying process through numerical simulations.In this study,we investigated the dynamic behavior of sand particles during a vibratory sand-laying process for multi-material additive manufacturing using discrete element simulations.The objective is to enable precise control over the amount and distribution of sand for multi-material printing.In this study,we combined experiments and simulations to calibrate the contact parameters of different sands and establish a relationship between the curing agent content and surface energy of sand particles.A model for the vibratory fall of multimaterial sand was developed to study the motion characteristics of sand particles.This allows for macro-control over the sand spreading flow and high-quality multi-material sand laying.The results show that the flow rate of falling sand increases with decreasing surface energy of the particles,wider spreader openings,and higher vibration frequencies.For silica and chromite sands,when their surface energy ranged from 0.15 to 25 J·m^(2)and0.01-0.03 J·m^(2),respectively,and the sand spreader opening was 6 mm with a vibration frequency of 500 Hz,the sand flow rates of both materials became nearly identical.However,a higher sand paving speed and height increased the scattering of sand particles outside the target area,thereby decreasing the paving quality.The results accomplished in this study enable precise and uniform sand particle deposition and offers guidelines for optimizing sand speed and height,thus expanding the application of multi-material sand 3D printing in complex and high-performance manufacturing.
基金supported by the National Natural Science Foundation of China(Grant No.52172356)the Hunan Provincial Natural Science Foundation of China(Grant No.2022JJ10012).
文摘The application of multi-material topology optimization affords greater design flexibility compared to traditional single-material methods.However,density-based topology optimization methods encounter three unique challenges when inertial loads become dominant:non-monotonous behavior of the objective function,possible unconstrained characterization of the optimal solution,and parasitic effects.Herein,an improved Guide-Weight approach is introduced,which effectively addresses the structural topology optimization problem when subjected to inertial loads.Smooth and fast convergence of the compliance is achieved by the approach,while also maintaining the effectiveness of the volume constraints.The rational approximation of material properties model and smooth design are utilized to guarantee clear boundaries of the final structure,facilitating its seamless integration into manufacturing processes.The framework provided by the alternating active-phase algorithm is employed to decompose the multi-material topological problem under inertial loading into a set of sub-problems.The optimization of multi-material under inertial loads is accomplished through the effective resolution of these sub-problems using the improved Guide-Weight method.The effectiveness of the proposed approach is demonstrated through numerical examples involving two-phase and multi-phase materials.
基金Funded by the National Key R&D Program of China(No.2021YFB3802300)the Foundation of National Key Laboratory of Shock Wave and Detonation Physics(No.JCKYS2022212004)the National Natural Science Foundation of China(No.52171045),and the Joint Fund(No.8091B022108)。
文摘The effects of pressure on the structural stability,elasticity,electronic properties,and thermodynamic properties of Al,Al_(3)Cu,Al_(2)Cu,Al_(4)Cu_(9),AlCu_(3),and Cu were investigated using first-principles calculations.The experimental results indicate that the calculated equilibrium lattice constant,elastic constant,and elastic modulus agree with both theoretical and experimental data at 0 GPa.The Young's modulus,bulk modulus,and shear modulus increase with increasing pressure.The influence of pressure on mechanical properties is explained from a chemical bond perspective.By employing the quasi-harmonic approximation model of phonon calculation,the temperature and pressure dependence of thermodynamic parameters in the range of 0 to 800 K and 0 to 100 GPa are determined.The findings demonstrate that the thermal capacity and coefficient of thermal expansion increase with increasing temperature and decrease with increasing pressure.This study provides fundamental data and support for experimental investigations and further theoretical research on the properties of aluminum-copper intermetallic compounds.
基金support from the National Natural Science Foundation of China(No.52374402)the National Key Research and Development Program(No.2022YFB3402200)+2 种基金the National Science and Technology Major Project(No.J2022-VII-0003-0045)the Project of Key areas of innovation team in Shaanxi Province(No.2024RS-CXTD-20)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(No.CX2024055).
文摘The vacuum reactive wetting and brazing of Er_(2)Si_(2)O_(7)/MoSi_(2) coatings were investigated using a (CoFeNiCrMn)_(88)Nb_(12) high-entropy alloy (HEA) brazing filler. The microstructural evolution and wettability of the HEA filler were analyzed, with particular attention to the surface energy, interfacial stability, and electronic properties of the HEA filler/rare earth silicate coating system, as determined by density functional theory (DFT). As Nb diffused into the interface and the ErNbO_(4) phase formed, the wetting angle gradually decreased to 23.12° The effective wetting and spreading of the HEA brazing filler on the rare earth silicate coating surface are strongly correlated with the formation of the ErNbO_(4) phase at the interface. Furthermore, DFT calculations reveal that the interfacial bonding energy between the BCC' and FCC' phases and the ErNbO_(4) phase, after the wetting reaction, is significantly higher than the bonding energy between the initial filler and Er_(2)Si_(2)O_(7). This finding suggests that the formation of the ErNbO_(4) phase improves the wetting and spreading behavior of the filler.
基金supported by the National Natural Science Foun-dation of China(Grant Nos.12393831 and 12088101).
文摘Control of hyperfine interaction strength of shallow donors in Si is one of the central issues in realizing Kane quantum computers.First-principles calculations on the hyperfine Stark shift of shallow donors are challenging since large supercells are needed to accommodate the delocalized donor wave functions.In this work,we investigated the hyperfine Stark shift and its strain tunability for shallow donors P and As in Si using the potential patching method based on first-principles density functional theory calculations.The good agreement between our calculations and experimental results confirms that the potential patching method is a feasible and accurate first-principles approach for studying wave-function-related properties of shallow impurities,such as the Stark shift parameter.It is further shown that the application of strain expands the range of hyperfine Stark shift and helps improve the response of shallow donor based qubit gates.The results could be useful for developing quantum computing architectures based on shallow donors in Si.
文摘Steel-concrete composite beams,due to their superior mechanical properties,are widely utilized in engineering structures.This study systematically investigates the calculation methods for internal forces and load-bearing capacity of composite beams based on elastic theory,with a focus on the transformed section method and its application under varying neutral axis positions.By deriving the geometric characteristics of the transformed section and incorporating a reduction factor accounting for slip effects,a computational model for sectional stress and ultimate load-bearing capacity is established.The results demonstrate that the slip effect significantly influences the flexural load-bearing capacity of composite beams.The proposed reduction factor,which considers the influence of the steel beam’s top flange thickness,offers higher accuracy compared to traditional methods.These findings provide a theoretical foundation for the design and analysis of composite beams,with significant practical engineering value.
基金Project(22376221)supported by the National Natural Science Foundation of ChinaProject(2024JJ2074)supported by the Natural Science Foundation of Hunan Province,ChinaProject(2023QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST。
文摘Understanding the adsorption behavior of heavy metals and metalloids on clay minerals is essential for remediating heavy metal-contaminated soils.The adsorption of heavy metals and metalloids on illite(001)and sodium montmorillonite(Na-MMT)(001)surfaces was investigated using first-principles calculations in this study,especially As atom and H_(3)AsO_(3) molecule.The adsorption energies of the As atom were−1.94 eV on the illite(001)and−0.56 eV on the Na-MMT(001),whereas,the adsorption energies of the H_(3)AsO_(3) molecule were−1.40 eV on illite(001)and−1.01 eV on Na-MMT(001).The above results indicate that the adsorption was more energetically favorable on illite(001).Additionally,compared to Na-MMT(001),there were more significant interactions between the atoms/molecules on the illite(001).After As atom and H_(3)AsO_(3) molecule adsorption,the electrons were transferred from mineral surface atoms to the adsorbates on both illite(001)and Na-MMT(001)surfaces.Moreover,the adsorption of As atom on illite(001)and Na-MMT(001)surfaces were more energy favorable compared to Hg,Cd,and Cr atoms.Overall,this work provides new insights into the adsorption behavior of As atoms and As molecules on illite and Na-MMT.The results indicate that illite rich soils are more prone to contamination by arsenic compared to soils primarily composed of Na-MMT minerals.
基金Zhejiang Provincial Natural Science Foundation of China for Young Scholars(Project No.:LQ20A020009)National College Students’Innovation and Entrepreneurship Training Program(Project No.:202311842014X)。
文摘The longitudinal cracks distributed along the dam axis in the corridor of a dam may have potential safety hazards.According to the detection results of crack depth and width and the analysis of monitoring data,a three-dimensional finite element model is established for numerical simulation calculation and the influence of cracks on the safety of dam structure is analyzed from different aspects such as deformation,stress value,and distribution range.The calculation results show that the maximum principal tensile stress value and the location of the dam body are basically independent of the change of crack depth(within 1.0 m).Regarding local stress around the corridor,the high upstream water level causes cracks to deepen,resulting in an increase in the maximum tensile stress near the crack tip and an expansion of the tensile stress region.
基金Supported by Beijing Natural Science Foundation from Beijing Municipal Government(No.7202030).
文摘AIM:To investigate the effect of pharmacological pupil alterations on intraocular lens(IOL)power calculations.METHODS:A systematic review and Meta-analysis of studies published before December 2023 in the PubMed,Embase,and Cochrane library databases on the accuracy of pharmacological pupil changes on IOL power calculation was performed.The primary outcome was the results of IOL power calculations before and after the use of medications.Subgroup analyses were performed based on participants’basic characteristics,such as age,axial length(AL),and whether miosis or mydriasis were used as classification criteria for further analyses.Each eligible study was evaluated for potential risk of bias by the AHRQ assessment scale.The study was registered on PROSPERO(CRD 42024497535).RESULTS:A total of 3062 eyes from 21 studies were eligible.There was no significant difference in the IOL power calculation before and after pharmacological pupil changes using any of the Hoffer Q(WMD=0.055,95%CI=-0.046–0.156;P=0.29),SRK/T(WMD=0.003,95%CI=-0.073–0.080;P=0.93),Haigis(WMD=-0.030,95%CI=-0.176–0.116;P=0.69),Holladay 2(WMD=-0.042,95%CI=-0.366–0.282;P=0.80),and Barrett Universal Ⅱ(WMD=0.033,95%CI=-0.061–0.127;P=0.49)formulas.On the measurement of parameters related to IOL power calculation,for either miosis or mydriasis AL(P=0.98 and 0.29,respectively),lens thickness(P=0.96 and 0.13,respectively),and mean keratometry(P=0.90 and 0.86,respectively)did not present significant differences,while anterior chamber depth(P=0.07 and<0.01,respectively)and white-to-white distance(P=0.01 and 0.04,respectively)changed significantly between the two measurements prior and posterior.At the same time,despite there being some participants with the difference between the before and after calculations greater than 0.5 diopter,there was no significant difference in the incidence rate between these formulas.CONCLUSION:There is no significant effect of pharmacological pupil changes on the IOL power calculation.It will considerably reduce the visit time burden for patients who require cataract surgery.
基金supported by the National Natural Science Foundation of China(Nos.52364044 and 52204364)Central Guidance on Local Science and Technology Development Fund Projects of Inner Mongolia Autonomous Region(No.2022ZY0090)Basic Scientific Research Business Expenses of Colleges and Universities in Inner Mongolia Autonomous Region(Nos.2023QNJS011 and 0406082226).
文摘The micro-area characterization experiments like scanning Kelvin probe force microscope(SKPFM)and Kernel average misorientation have the defects of complex sample preparation and occasional errors in test results,which makes it impossible to accurately and quickly analyze the pitting behavior induced by inclusions in some cases,prompting attempts to turn to simulation calculation research.The method of calculating band structure and work function can be used to replace current-sensing atomic force microscopy and SKPFM to detect the potential and conductivity of the sample.The band structure results show that Al_(2)O_(3) inclusion is an insulator and non-conductive,and it will not form galvanic corrosion with the matrix.Al_(2)O_(3) inclusion does not dissolve because its work function is higher than that of the matrix.Moreover,the stress concentration of the matrix around the inclusion can be characterized by first-principles calculation coupled with finite element simulation.The results show that the stress concentration degree of the matrix around Al_(2)O_(3) inclusion is serious,and the galvanic corrosion is formed between the high and the low stress concentration areas,which can be used to explain the reason of the pitting induced by Al_(2)O_(3) inclusions.
基金supported by the National Key Research and Development Program of China(No.2022YFB4600900).
文摘In this study,6061 aluminum alloy and galvanized steel fusion-brazed lap joints were obtained using a laser-arc hybrid heat source,and the effects of laser power variation on the microstructure,mechanical properties,and fracture mechanism of the joints were ana-lyzed.The results showed that the tensile shear load initially increased with rising laser power,followed by a decrease.At a laser power of 240 W,the maximum tensile shear load was 2479.8 N/cm and the weak section of joint was in the Al-Fe reaction layer con-sisting of Fe(Al,Si)_(3),Fe_(2)(Al,Si)_(5),and Fe(Al,Si)intermetallic compounds(IMCs).Computational results showed that the inherently high brittleness and hardness of Fe(Al,Si)_(3) and the high mismatch rates of Fe(Al,Si)_(3)/Al interfaces were the key factor leading to the failure of the joints at lower heat input.
基金supported by the National Key R&D Program of China(Nos.2024YFE0109800 and 2024YFE0109802)the National Natural Science Foundation of China(Nos.12405141,12347106,12205340,and 12121005)+1 种基金the Gansu Natural Science Foundation(No.25JRRA467)the Key Research Program of the Chinese Academy of Sciences(No.XDPB15)。
文摘Neutron-rich boron,carbon,and nitrogen isotopes have garnered extensive experimental and theoretical interest.In the present work,we conducted a comprehensive study of these nuclei by utilizing ab initio valence-space in-medium similarity renormalization group calculations with chiral nucleon-nucleon and three-nucleon interactions.First,we systematically calculated the spectra of nuclei.Our results align well with the available experimental data,which are comparable to phenomenological shell model calculations.Subsequently,the evolution of the N=14 and N=16 shell gaps is discussed based on the calculated spectra and the effective single-particle energies.Our calculations suggest that the N=14 neutron subshell is present in the oxygen isotopes but disappears in the boron,carbon,and nitrogen isotopic chains.Moreover,the N=16 subshell is present in all isotopes but gradually decreases from^(24)O to^(21)B.These results provide valuable information for future studies.
基金supported by the National Natural Science Foundation of China(Nos.52271172,and 51971085).
文摘Ni-Mn-Ti Heusler alloys have great potential for elastocaloric refrigeration due to the colossal caloric effect and good mechanical properties. However, theoretical calculations on the characterization of the elastocaloric effect are rare. An important parameter to evaluate the elastocaloric effect is the transformation entropy change, whose main source is the vibrational entropy change (ΔS_(vib)). Unfortunately, the widely used quasiharmonic approximation method fails in the prediction of the vibrational entropy for high-temperature austenite due to its dynamical instability at 0 K. To solve this problem, the temperature dependent effective potential method was used considering the temperature and anharmonic effect. Sc, V, and Zr doping at the Ti sites in B2 disordered Ni_(8)Mn_(5)Ti_(3) were studied about phase stability, martensitic transformation, and elastocaloric properties. The results revealed the austenitic structures of all the doping systems exhibit antiferromagnetic coupling characteristics at 300 K due to the temperature effect. Sc and Zr doping at the Ti sites decreased the ΔS_(vib) value, whereas V doping at the Ti site increased the ΔS_(vib) value. Further analysis proved the important evaluation criterion that the ΔS_(vib) value increases with the tetragonal distortion ratio and volume change, which has important guiding significance for improving the elastocaloric effect. Besides, the calculations of elastic constants presented all the doping systems maintain outstanding ductility evaluated from the B/G ratio. This work provides an effective strategy for designing excellent elastocaloric material with large vibrational entropy change and good mechanical properties.
基金supported by the National Natural Science Foundation of China(Nos.22207036,22277034,22477034,and 22107033)Interdisciplinary Research Program of Huazhong University of Science and Technology(No.2023JCYJ037)International Cooperation Project of Hubei Provincial Key R&D Plan(No.2023EHA040)。
文摘Two pairs of novel 6/6/6/9 tetracyclic merosesquiterpenoid enantiomers,dauroxonanols A(1)and B(2),possessing an unprecedented 9,15-dioxatetracyclo[8.5.3.0^(4.17).0^(14.18)]octadecane core skeleton,were isolated from Rhododendron dauricum.The nuclear magnetic resonance(NMR)spectra of 1 and 2 showed very broad resonances,and^(13)C NMR spectrum of 1 exhibited only 13 instead of 22 carbon resonances.These broadening or missing NMR resonances led to a great challenge to elucidate their structures using NMR data analysis.Their structures and absolute configurations of 1 and 2 were finally determined by single crystal X-ray diffraction analysis,chiral separation,and electronic circular dichroism(ECD)calculations.Plausible biosynthetic pathways for 1 and 2 are proposed.Conformational analysis,density functional theory(DFT)calculations,and dynamic NMR assigned the coalescent NMR phenomena of 1 and 2 to the conformational changes of the flexible oxonane ring.Dauroxonanols A(1)and B(2)showed potentα-glucosidase inhibitory activities,2-8 times potent than acarbose,an antidiabetic drug targetingα-glucosidase in clinic.
