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First-principles calculation on the electronic structures, phonon dynamics, and electrical conductivities of Pb_(10)(PO_(4))_(6O) and Pb_(9)Cu(PO_(4))_(6O) compounds

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Journal of Materials Science & Technology 2024年第6期173卷 218-224页

作者： L.y.Hao E.g.Fu State Key Laboratory of Nuclear Physics and Technology Department of Technical PhysicsSchool of PhysicsPeking UniversityBeijing 100871China

Superconducting materials with high critical temperature have the potential to revolutionize many fields,including military,electronic communications,and power ***,scientists around the world have been tirelessly working with the ultimate goal of achieving high-temperature *** 2023,a preprint by Lee et *** South Korea claimed the discovery of ultra-high-temperature superconductivity with a critical temperature of up to 423 K in Cu-doped lead-apatite(LK-99)(arXiv:2307.12008,arXiv:2307.12037),which caused a worldwide sensation and ***,the electronic structures,phonon dynamics,and electrical conductivities of LK-99 and its parent compound lead-apatite have been calculated using first-principles *** results show that the lead-apatite compound and the LK-99 compound are insulator and half-metal *** flat band characteristic is consistent with previous *** electrical conductivity of the LK-99 compound shows two extreme points,and the electrical conductivity along the C-axis increases significantly after 400 *** phonon dispersion spectra of the compounds were investigated,demonstrating their dynamic instability.

关键词： Superconductivity LK-99 Lead-apatite First-principles calculation

Supposition of graphene stacks to estimate the contact resistance and conductivity of nanocomposites

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 663-676页

作者： y.ZARE M.T.MUNIR g.J.WENg K.y.RHEE Biomaterials and Tissue Engineering Research group Department of Interdisciplinary TechnologiesBreast Cancer Research CenterMotamed Cancer InstituteTehran ***Iran College of Engineering and Technology American University of the Middle EastEgaila 54200Kuwait Department of Mechanical and Aerospace Engineering Rutgers UniversityNew BrunswickNJ 08903U.S.A. Department of Mechanical Engineering(BK21 Four) College of EngineeringKyung Hee UniversityYongin 446701Republic of Korea

In this study,the effects of stacked nanosheets and the surrounding interphase zone on the resistance of the contact region between nanosheets and the tunneling conductivity of samples are evaluated with developed equations superior to those previously *** contact resistance and nanocomposite conductivity are modeled by several influencing factors,including stack properties,interphase depth,tunneling size,and contact *** developed model's accuracy is verified through numerous experimental *** further validate the models and establish correlations between parameters,the effects of all the variables on contact resistance and nanocomposite conductivity are ***,the contact resistance is primarily dependent on the polymer tunnel resistivity,contact area,and tunneling *** dimensions of the graphene nanosheets significantly influence the conductivity,which ranges from 0 S/m to90 S/*** increased number of nanosheets in stacks and a larger gap between them enhance the nanocomposite's ***,the thicker interphase and smaller tunneling size can lead to higher sample conductivity due to their optimistic effects on the percolation threshold and network efficacy.

关键词： graphene polymer composite stacked nanosheet tunneling conductivity contact resistance interphase

Direct 4D printing of functionally graded hydrogel networks for biodegradable,untethered,and multimorphic soft robots

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International Journal of Extreme Manufacturing 2024年第2期6卷 407-416页

作者： Soo young cho Dong Hae Ho Sae Byeok Jo Jeong Ho cho Department of Chemical and Biomolecular Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Mechanical Engineering Virginia TechBlacksburgVA 24061United States of America School of Chemical Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea SKKU Institute of Energy Science and Technology(SIEST) Sungkyunkwan UniversitySuwon 16419Republic of Korea

Recent advances in functionally graded additive manufacturing(FgAM)technology have enabled the seamless hybridization of multiple functionalities in a single *** robotics can become one of the largest beneficiaries of these advances,through the design of a facile four-dimensional(4D)FgAM process that can grant an intelligent stimuli-responsive mechanical functionality to the printed ***,we present a simple binder jetting approach for the 4D printing of functionally graded porous multi-materials(FgMM)by introducing rationally designed graded multiphase feeder *** graded cross-linking agents gradually form stable porous network structures within aqueous polymer particles,enabling programmable hygroscopic deformation without complex mechanical ***,a systematic bed design incorporating additional functional agents enables a multi-stimuli-responsive and untethered soft robot with stark stimulus *** biodegradability of the proposed 4D-printed soft robot further ensures the sustainability of our approach,with immediate degradation rates of 96.6%within 72 *** proposed 4D printing concept for FgMMs can create new opportunities for intelligent and sustainable additive manufacturing in soft robotics.

关键词： intelligent and sustainable additive manufacturing multi-material four-dimensional printing untethered soft robot multi-stimuli-responsive soft robot biodegradable soft robotics

Thermodynamic model for deoxidation of liquid steel considering strong metal-oxygen interaction in the quasichemical model framework

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 988-1002页

作者： yong-Min cho youn-Bae Kang graduate Institute of Ferrous and Eco Materials Technology Pohang University of Science and TechnologyPohangKyungbuk37673Rep.of Korea N.EX.T Hub POSCO HoldingsPohangKyungbuk37673Rep.of Korea Department of Materials Science and Engineering Pohang University of Science and TechnologyPohangKyungbuk37673Rep.of Korea

Herein,a thermodynamic model aimed at describing deoxidation equilibria in liquid steel was *** model provides explicit forms of the activity coefficient of solutes in liquid steel,eliminating the need for the minimization of internal gibbs energy preliminarily when solving deoxidation *** elimination of internal gibbs energy minimization is particularly advantageous during the coupling of deoxidation equilibrium calculations with computationally intensive approaches,such as computational fluid *** model enables efficient calculations through direct embedment of the explicit forms of activity coefficient in the computing *** proposed thermodynamic model was developed using a quasichemical approach with two key approximations:random mixing of metallic elements(Fe and oxidizing metal) and strong nonrandom pairing of metal and oxygen as nearest *** these approximations,the quasichemical approach yielded the activity coefficients of solutes as explicit functions of composition and temperature without requiring the minimization of internal gibbs energy or the coupling of separate *** model was successfully applied in the calculation of deoxidation equilibria of various elements(Al,B,C,Ca,Ce,Cr,La,Mg,Mn,Nb,Si,Ti,V,and Zr).The limitations of the model arising from these assumptions were also discussed.

关键词： deoxidation equilibria thermodynamics quasichemical approach computational fluid dynamics

Ungraded Matrix Factorizations as Mirrors of Non-orientable Lagrangians

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Acta Mathematica Sinica,English Series 2024年第1期40卷 26-42页

作者： Lino AMORIM Cheol-Hyun cho Department of Mathematics Kansas State University138 Cardwell Hall1228 N.17th StreetManhattanKS 66506USA Department of Mathematical Sciences Research Institute of MathematicsSeoul National UniversitySan 56-1ShinrimdongGwanakguSeoul 47907South Korea

We introduce the notion of ungraded matrix factorization as a mirror of non-orientable Lagrangian *** ungraded matrix factorization of a polynomial W,with coefficients in a field of characteristic 2,is a square matrix Q of polynomial entries satisfying Q^(2)=W·*** then show that non-orientable Lagrangians correspond to ungraded matrix factorizations under the localized mirror functor and illustrate this construction in a few *** main example is the Lagrangian submanifold RP^(2)⊂CP^(2)and its mirror ungraded matrix factorization,which we construct and *** particular,we prove a version of Homological Mirror Symmetry in this setting.

关键词： Mirror symmetry non-orientable Lagrangian submanifold matrix factorization

Optimization of chemistry and process parameters for control of intermetallic formation in Mg sludges

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Journal of Magnesium and Alloys 2024年第4期12卷 1431-1448页

作者： y.Fu g.g.Wang A.Hu y.Li K.B.Thacker J.P.Weiler H.Hu Department of Mechanical Automotive and Materials EngineeringUniversity of Windsor401 Sunset AveWindsorOntario N9B 3P4Canada global Technology Centre Meridian Lightweight Technologies25 MacNab AveStrathroyOntario N7G 4H6Canada

Intermetallic formation in sludge during magnesium(Mg)melting,holding and high pressure die casting practices is a very important ***,very often it is overlooked by academia,original equipment manufacturers(OEM),metal ingot producers and even die *** aim of this study was to minimize the intermetallic formation in Mg sludge via the optimization of the chemistry and process *** Al8Mn5 intermetallic particles were identified by the microstructure analysis based on the Al and Mn *** design of experiment(DOE)technique,Taguchi method,was employed to minimize the intermetallic formation in the sludge of Mg alloys with various chemical compositions of Al,Mn,Fe,and different process parameters,holding temperature and holding *** sludge yield(Sy)and intermetallic size(IS)was selected as two *** optimum combination of the levels in terms of minimizing the intermetallic formation were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,690℃ for the holding temperature and holding at 30 mins for the holding time,*** best combination for smallest intermetallic size were 9 wt.%Al,0.15 wt.%Mn,0.001 wt.%(10 ppm)Fe,630℃ for the holding temperature and holding at 60 mins for the holding time,*** groups of sludge factors,Chemical Sludge(CSF),Physical Sludge(PSF)and Comprehensive Sludge Factors(and CPSF)were established for prediction of sludge yields and intermetallic sizes in Al-containing Mg *** CPSF with five independent variables including both chemical elements and process parameters gave high accuracy in prediction,as the prediction of the PSF with only the two processing parameters of the melt holding temperature and time showed a relatively large deviation from the experimental *** Chemical Sludge Factor was primarily designed for small ingot producers and die casters with a limited melting and holding capacity,of which process parameters could be fixed *** Physical Sludge Factor could be used f

关键词： Magnesium sludge Al-Mn intermetallic Optimization Taguchi method Sludge factor Chemical composition Process parameter

An Empirical Study on the Effectiveness of Adversarial Examples in Malware Detection

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 3535-3563页

作者： younghoon Ban Myeonghyun Kim Haehyun cho School of Software Soongsil UniversitySeoul06978Korea

Antivirus vendors and the research community employ Machine Learning(ML)or Deep Learning(DL)-based static analysis techniques for efficient identification of new threats,given the continual emergence of novel malware *** the other hand,numerous researchers have reported that Adversarial Examples(AEs),generated by manipulating previously detected malware,can successfully evade ML/DL-based *** antivirus systems,in particular,have been identified as vulnerable to such *** paper firstly focuses on conducting black-box attacks to circumvent ML/DL-based malware *** attack method utilizes seven different perturbations,including Overlay Append,Section Append,and Break Checksum,capitalizing on the ambiguities present in the PE format,as previously employed in evasion attack *** directly applying the perturbation techniques to PE binaries,our attack method eliminates the need to grapple with the problem-feature space dilemma,a persistent challenge in many evasion attack *** a black-box attack,our method can generate AEs that successfully evade both DL-based and ML-based ***,AEs generated by the attack method retain their executability and malicious behavior,eliminating the need for functionality *** thorogh evaluations,we confirmed that the attack method achieves an evasion rate of 65.6%against well-known ML-based malware detectors and can reach a remarkable 99%evasion rate against well-known DL-based malware ***,our AEs demonstrated the capability to bypass detection by 17%of vendors out of the 64 on VirusTotal(VT).In addition,we propose a defensive approach that utilizes Trend Locality Sensitive Hashing(TLSH)to construct a similarity-based defense *** several experiments on the approach,we verified that our defense model can effectively counter AEs generated by the perturbation *** conclusion,our defense model alleviates the limitation of the mos

关键词： Malware classification machine learning adversarial examples evasion attack cybersecurity

Construction of 2D/2D Ti_(3)C_(2)T_(x)MXene/CdS heterojunction with photothermal effect for efficient photocatalytic hydrogen production

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Journal of Materials Science & Technology 2024年第4期171卷 1-9页

作者： T.y.Huang Z.yang S.y.yang Z.H.Dai y.J.Liu J.H.Liao g.y.Zhong Z.J.Xie y.P.Fang S.S.Zhang Key Laboratory for Biobased Materials and Energy of Ministry of Education Guangdong Laboratory for Lingnan Modern AgricultureCollege of Materials and EnergySouth China Agricultural UniversityGuangzhou 510643China School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China School of Chemical Engineering and Energy Technology Guangdong Provincial Key Laboratory of Distributed Energy SystemsDongguan University of TechnologyDongguan 523808China

The insensitivity of semiconductors to visible and infrared light is a key constraint on the utilization of light energy in photocatalytic *** photocatalysts with full-spectrum absorption through surface engineering is an effective approach to fully harnessing light energy in semiconductor ***,a novel stable Ti_(3)C_(2)T_(x)MXene/CdS heterojunction catalyst is obtained by in-situ epitaxial growth of two-dimensional(2D)CdS nanosheets on 2D MXene interface via a solvothermal *** exceptional light absorption properties of MXene confer outstanding full-spectrum driven photocat-alytic hydrogen evolution capability upon the heterogeneous *** unique 2D/2D structure effectively mitigated the recombination of photogenerated carriers,enhancing the photocatalytic performance of the ***,the composite catalyst exhibits a significantly higher surface temperature of 80.4℃under visible light irradiation at an intensity of 0.1 W/cm^(2),which is 1.84 times higher than that of *** irradiation of visible and near infrared light,the composite catalyst with photothermal ef-fect demonstrates a remarkable hydrogen evolution rate of 65.4 mmol g^(-1)h^(-1),which is 7.2 times higher than that of CdS *** study introduces a novel approach for constructing full-spectrum absorption catalysts and expands the application of the photothermal effect in photocatalytic hydrogen evolution research.

关键词： Two-dimensional structure Heterostructure Photothermal effect Photocatalyst Hydrogen evolution

In-situ construction of grass-like hybrid architecture responsible for extraordinary corrosion performance: Experimental and theoretical approach

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Nano Materials Science 2024年第1期6卷 44-59页

作者： T.Suhartono F.Hazmatulhaq y.Sheng A.Chaouiki M.P.Kamil y.g.Ko Materials Electrochemistry group School of Materials Science and EngineeringYeungnam UniversityGyeongsan38541Republic of Korea Research Center for Advanced Materials National Research and Innovation Agency(BRIN)South TangerangBanten15314Indonesia

Despite the engineering potential by the co-existence of inorganic and organic substances to protect vulnerable metallic materials from corrosive environments,both their interaction and in-situ formation mechanism to induce the nature-inspired composite remained less *** present work used three distinctive mercaptobenzazole(MB)compounds working as corrosion inhibitors,such as 2-mercaptobenzoxazole(MBO),2-mercaptobenzothiazole(MBT),and 2-mercaptobenzimidazole(MBI)in a bid to understand how the geometrical structure arising from O,S,and N atoms affected the interaction toward inorganic *** compounds that were used here to control the corrosion kinetics would be interacted readily with the pre-existing MgO layer fabricated by plasma *** phenomenon triggered the nucleation of the root network since MB compounds were seen to be adsorbed actively on the defective surface through the active sites in MB ***,the molecule with twin donor atoms adjacent to the mercapto-sites affected the facile growth of the grass-like structures with‘uniform’distribution via molecular self-assembly,which showed better corrosion performance than those with having dissimilar donor atoms with the inhibition efficiency(η)of 97%*** formation mechanism underlying nucleation and growth behavior of MB molecule was discussed concerning the theoretical calculation of density functional theory.

关键词： Nature-inspired composite Organic-inorganic interaction Corrosion inhibitor Density functional theory Electrochemistry