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Temperature-Induced Unfolding Pathway of Staphylococcal Enterotoxin B:Insights from Circular Dichroism and Molecular Dynamics Simulation 被引量:1
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作者 LIU Ji ZHANG Shiyu +1 位作者 ZENG Yu DENG Yi 《食品科学》 EI CAS CSCD 北大核心 2024年第18期55-76,共22页
In this study,circular dichroism(CD)and molecular dynamics(MD)simulation were used to investigate the thermal unfolding pathway of staphylococcal enterotoxin B(SEB)at temperatures of 298–371 and 298–500 K,and the re... In this study,circular dichroism(CD)and molecular dynamics(MD)simulation were used to investigate the thermal unfolding pathway of staphylococcal enterotoxin B(SEB)at temperatures of 298–371 and 298–500 K,and the relationship between the experimental and simulation results were explored.Our computational findings on the secondary structure of SEB showed that at room temperature,the CD spectroscopic results were highly consistent with the MD results.Moreover,under heating conditions,the changing trends of helix,sheet and random coil obtained by CD spectral fitting were highly consistent with those obtained by MD.In order to gain a deeper understanding of the thermal stability mechanism of SEB,the MD trajectories were analyzed in terms of root mean square deviation(RMSD),secondary structure assignment(SSA),radius of gyration(R_(g)),free energy surfaces(FES),solvent-accessible surface area(SASA),hydrogen bonds and salt bridges.The results showed that at low heating temperature,domain Ⅰ without loops(omitting the mobile loop region)mainly relied on hydrophobic interaction to maintain its thermal stability,whereas the thermal stability of domain Ⅱ was mainly controlled by salt bridges and hydrogen bonds.Under high heating temperature conditions,the hydrophobic interactions in domain Ⅰ without loops were destroyed and the secondary structure was almost completely lost,while domain Ⅱ could still rely on salt bridges as molecular staples to barely maintain the stability of the secondary structure.These results help us to understand the thermodynamic and kinetic mechanisms that maintain the thermal stability of SEB at the molecular level,and provide a direction for establishing safer and more effective food sterilization processes. 展开更多
关键词 staphylococcal enterotoxin B circular dichroism molecular dynamics simulations temperature-induced unfolding
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Molecular Dynamics Simulation of Shock Response of CL-20 Co-crystals Containing Void Defects 被引量:1
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作者 Changlin Li Wei Yang +5 位作者 Qiang Gan Yajun Wang Lin Liang Wenbo Zhang Shuangfei Zhu Changgen Feng 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第1期364-374,共11页
To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitro... To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force field.It is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the void.The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro groups.The existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly.Detonation has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by voids.The results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals. 展开更多
关键词 CL-20 co-crystals molecular dynamics simulation Reactive forcefield Impact response Hot spot Void defect
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Revealing Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles in oxygen/fluorine containing environments:A reactive molecular dynamics study meshing together experimental validation 被引量:1
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作者 Gang Li Chuande Zhao +2 位作者 Qian Yu Fang Yang Jie Chen 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第4期313-327,共15页
Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For inst... Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For instance,Al-O reaction is the most common pathway to release limited energy while Al-F reaction has received much attentions to enhance Al combustion efficiency.However,microscopic understanding of the Al-O/Al-F reaction dynamics remains unsolved,which is fundamentally necessary to further improve Al combustion efficiency.In this work,for the first time,Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles(n-Al)in oxygen/fluorine containing environments have been revealed via reactive molecular dynamics(RMD)simulations meshing together combustion experiments.Three RMD simulation systems of Al core/O_(2)/HF,n-Al/O_(2)/HF,and n-Al/O_(2)/CF4 with oxygen percentage ranging from 0%to 100%have been performed.The n-Al combustion in mixed O_(2)/CF_4 environments have been conducted by constant volume combustion experiments.RMD results show that Al-O reaction exhibits kinetic benefits while Al-F reaction owns thermodynamic benefits for n-Al combustion.In n-Al/O_(2)/HF,Al-O reaction gives faster energy release rate than Al-F reaction(1.1 times).The optimal energy release efficiency can be achieved with suitable oxygen percentage of 10%and 50%for n-Al/O_(2)/HF and n-Al/O_(2)/CF_4,respectively.In combustion experiments,90%of oxygen percentage can optimally enhance the peak pressure,pressurization rate and combustion heat.Importantly,Al-O reaction prefers to occur on the surface regions while Al-F reaction prefers to proceed in the interior regions of n-Al,confirming the kinetic/thermodynamic benefits of Al-O/Al-F reactions.The synergistic effect of Al-O/Al-F reaction for greatly enhancing n-Al combustion efficiency is demonstrated at atomicscale,which is beneficial for optimizing the combustion performance of metallic fuel. 展开更多
关键词 Al-O/Al—F reaction Kinetic benefits Thermodynamic benefits molecular dynamics COMBUSTION
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Machine learning molecular dynamics simulations of liquid methanol
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作者 Jie Qian Junfan Xia Bin Jiang 《中国科学技术大学学报》 CAS CSCD 北大核心 2024年第6期12-21,I0009,I0010,共12页
As the simplest hydrogen-bonded alcohol,liquid methanol has attracted intensive experimental and theoretical interest.However,theoretical investigations on this system have primarily relied on empirical intermolecular... As the simplest hydrogen-bonded alcohol,liquid methanol has attracted intensive experimental and theoretical interest.However,theoretical investigations on this system have primarily relied on empirical intermolecular force fields or ab initio molecular dynamics with semilocal density functionals.Inspired by recent studies on bulk water using increasingly accurate machine learning force fields,we report a new machine learning force field for liquid methanol with a hybrid functional revPBE0 plus dispersion correction.Molecular dynamics simulations on this machine learning force field are orders of magnitude faster than ab initio molecular dynamics simulations,yielding the radial distribution functions,selfdiffusion coefficients,and hydrogen bond network properties with very small statistical errors.The resulting structural and dynamical properties are compared well with the experimental data,demonstrating the superior accuracy of this machine learning force field.This work represents a successful step toward a first-principles description of this benchmark system and showcases the general applicability of the machine learning force field in studying liquid systems. 展开更多
关键词 liquid methanol molecular dynamics machine learning hydrogen bond force field
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Study on the Mechanism of Nanopatterning in Printed Electronics Based on Molecular Dynamics Simulation
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作者 HUANG Hai-yang LI Yan ZHANG Run-liang 《印刷与数字媒体技术研究》 CAS 北大核心 2024年第4期237-244,共8页
In order to research the feasibility of using the selective adsorption principle to achieve automatic shaping of nano patterns,in this study,using the liquid gallium as the conductive ink and graphene as the printing ... In order to research the feasibility of using the selective adsorption principle to achieve automatic shaping of nano patterns,in this study,using the liquid gallium as the conductive ink and graphene as the printing plate surface,by changing the surface wettability of patterned areas on the nanoscale of graphene printed boards,the automatic formation of liquid gallium patterns on the graphene printed plate surface was simulated.The results indicated that liquid gallium can achieve automatic patterning on the surface of graphene patterned areas;the greater the interaction energy between gallium and carbon atoms,the clearer the pattern;gallium liquid is prone to remain in complex local positions of the pattern,making it difficult to shape the pattern;if the spacing between adjacent pattern lines is too large or too small,it will result in residual gallium liquid between the lines;increasing the thickness of the gallium film will cause the pattern to expand beyond the boundary,but increasing the thickness of the gallium film can also enhance the thickness and uniformity of the pattern lines.In summary,the principle of selective adsorption can be used to achieve the automatic formation of nano patterns,and the pattern formation effect is influenced by factors such as atomic interaction energy and pattern configuration. 展开更多
关键词 molecular dynamics Liquid gallium GRAPHENE Pattern forming
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Anti-sintering behavior and combustion process of aluminum nano particles coated with PTFE:A molecular dynamics study 被引量:6
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作者 Jun-peng Liu Hao-rui Zhang Qi-Long Yan 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第6期46-57,共12页
The characteristic of easy sintering of aluminum nanoparticle(ANP)limits its application in solid propellants.Coating ANP with fluoropolymer could effectively improve its combustion performance.To find out how the coa... The characteristic of easy sintering of aluminum nanoparticle(ANP)limits its application in solid propellants.Coating ANP with fluoropolymer could effectively improve its combustion performance.To find out how the coating layer inhibits sintering and promotes complete combustion of particles from an atomic view,a comparative study has been done for bare ANP and PTFE coated ANP by using reactive molecular dynamics simulations.The sintering process is quantified by shrinkage ratio and gyration radius.Our results show that,at the same heating rate and combustion temperatures,bare ANPs are sintered together after the temperature exceeds the melting point of aluminum but the decomposition of PTFE coating layer pushes particles away and increases reaction surface area by producing small Al-F clusters.The sintering of ANPs which are heated in PTFE is alleviated compared with particles heated in oxygen,but particles still sinter together due to the lack of intimate contact between PTFE and alumina surface.The effect of temperature on the combustion of PTFE coated ANPs is also studied from 1000 to3500 K.The number density analysis shows the particles will not be sintered at any temperature.Aluminum fluoride prefers diffusing to the external space and the remained particles are mainly composed of Al,C and O.Fast ignition simulations are performed by adopting micro canonical ensemble.With the expansion of aluminum core and the melting of alumina shell,bare ANPs are sintered into a liquid particle directly.For PTFE coated ANPs,the volatilization of gaseous aluminum fluoride products continually endows particles opposite momentum. 展开更多
关键词 Aluminum nanoparticle SINTERING Combustion molecular dynamics simulation
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Quantitative prediction and ranking of the shock sensitivity ofexplosives via reactive molecular dynamics simulations 被引量:5
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作者 Kun Yang Lang Chen +3 位作者 Dan-yang Liu De-shen Geng Jian-ying Lu Jun-ying Wu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2022年第5期843-854,共12页
A deep understanding of explosive sensitivities and their factors is important for safe and reliable applications.However,quantitative prediction of the sensitivities is difficult.Here,reactive molecular dynamics simu... A deep understanding of explosive sensitivities and their factors is important for safe and reliable applications.However,quantitative prediction of the sensitivities is difficult.Here,reactive molecular dynamics simulation models for high-speed piston impacts on explosive supercells were established.Simulations were also performed to investigate shock-induced reactions of various high-energy explosives.The fraction of reacted explosive molecules in an initial supercell changed linearly with the propagation distance of the shock-wave front.The corresponding slope could be used as a reaction rate for a specific shock-loading velocity.Reaction rates that varied with the shock-loading pressure exhibited two-stage linearities with different slopes.The two inflection points corresponded to the initial and accelerated reactions,which respectively correlated to the thresholds of shock-induced ignition and detonation.Therefore,the ignition and detonation critical pressures could be determined.The sensitivity could then be a quantitative prediction of the critical pressure.The accuracies of the quantitative shock sensitivity predictions were verified by comparing the impact and shock sensitivities of common explosives and the characteristics of anisotropic shock-induced reactions.Molecular dynamics simulations quantitatively predict and rank shock sensitivities by using only crystal structures of the explosives.Overall,this method will enable the design and safe use of explosives. 展开更多
关键词 EXPLOSIVE Shock sensitivity Quantitative prediction Reactive molecular dynamics simulation
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A molecular dynamics study of calcium silicate hydrates-aggregate interfacial interactions and influence of moisture 被引量:4
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作者 ZHOU Yang PENG Ze-chuan +3 位作者 HUANG Jia-le MA Tao HUANG Xiao-ming MIAO Chang-wen 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第1期16-28,共13页
The interface properties between hydrated cement paste(hcp)and aggregates largely determine the various performances of concrete.In this work,molecular dynamics simulations were employed to explore the atomistic inter... The interface properties between hydrated cement paste(hcp)and aggregates largely determine the various performances of concrete.In this work,molecular dynamics simulations were employed to explore the atomistic interaction mechanisms between the commonly used aggregate phase calcite/silica and calcium silicate hydrates(C-S-H),as well as the effect of moisture.The results suggest that the C-S-H/calcite interface is relatively strong and stable under both dry and moist conditions,which is caused by the high-strength interfacial connections formed between calcium ions from calcite and high-polarity non-bridging oxygen atoms from the C-S-H surface.Silica can be also adsorbed on the dry C-S-H surface by the H-bonds;however,the presence of water molecules on the interface may substantially decrease the affinities.Furthermore,the dynamics interface separation tests of C-S-H/aggregates were also implemented by molecular dynamics.The shape of the calculated stress-separation distance curves obeys the quasi-static cohesive law obtained experimentally.The moisture conditions and strain rates were found to affect the separation process of C-S-H/silica.A wetter interface and smaller loading rate may lead to a lower adhesion strength.The mechanisms interpreted here may shed new lights on the understandings of hcp/aggregate interactions at a nano-length scale and creation of high performance cementitious materials. 展开更多
关键词 calcium silicate hydrate AGGREGATE interfacial connections molecular dynamics simulation MOISTURE
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Parallelization and performance tuning of molecular dynamics code with OpenMP 被引量:3
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作者 白树仁 冉丽萍 鲁奎麟 《Journal of Central South University of Technology》 2006年第3期260-264,共5页
An OpenMP approach was proposed to parallelize the sequential molecular dynamics(MD) code on shared memory machines. When a code is converted from the sequential form to the parallel form, data dependence is a main pr... An OpenMP approach was proposed to parallelize the sequential molecular dynamics(MD) code on shared memory machines. When a code is converted from the sequential form to the parallel form, data dependence is a main problem. A traditional sequential molecular dynamics code is anatomized to find the data dependence segments in it, and the two different methods, i.e., recover method and backward mapping method were used to eliminate those data dependencies in order to realize the parallelization of this sequential MD code. The performance of the parallelized MD code was analyzed by using some performance analysis tools. The results of the test show that the computing size of this code increases sharply form 1 million atoms before parallelization to 20 million atoms after parallelization, and the wall clock during computing is reduced largely. Some hot-spots in this code are found and optimized by improved algorithm. The efficiency of parallel computing is 30% higher than that of before, and the calculation time is saved and larger scale calculation problems are solved. 展开更多
关键词 system analysis molecular dynamics parallel computing performance tuning OPENMP
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Effects of tensile temperatures on phase transformations in zirconium by molecular dynamics simulations 被引量:1
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作者 AN Ke-ying OU Xiao-qin +3 位作者 AN Xing-long ZHANG Hao NI Song SONG Min 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第7期1932-1945,共14页
The effects of tensile temperatures ranging from 100 K to 900 K on the phase transition of hexagonal close-packed(HCP)zirconium were investigated by molecular dynamics simulations,which were combined with experimental... The effects of tensile temperatures ranging from 100 K to 900 K on the phase transition of hexagonal close-packed(HCP)zirconium were investigated by molecular dynamics simulations,which were combined with experimental observation under high resolution transmission electron microscopy.The results show that externally applied loading first induced the HCP to body-centered cubic(BCC)phase transition in the Pitsch-Schrader(PS)orientation relationship(OR).Then,the face-centered cubic(FCC)structure transformed from the BCC phase in the Bain path.However,the HCP-to-BCC transition was incomplete at 100 K and 300 K,resulting in a prismatic-type OR between the FCC and original HCP phase.Additionally,at the temperature ranging from 100 K to 600 K,the inverse BCC-to-HCP transition occurred locally following other variants of the PS OR,resulting in a basal-type relation between the newly generated HCP and FCC phases.A higher tensile temperature promoted the amount of FCC phase transforming into the BCC phase when the strain exceeded 45%.Besides,the crystal stretched at lower temperatures exhibits relatively higher strength but by the compromise of plasticity.This study reveals the deformation mechanisms in HCP-Zr at different temperatures,which may provide a better understanding of the deformation mechanism of zirconium alloys under different application environments. 展开更多
关键词 ZIRCONIUM phase transformation molecular dynamics simulation deformation mechanism tensile temperature
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Free Energy Change of Micelle Formation for Sodium Dodecyl Sulfate from a Dispersed State in Solution to Complete Micelles along Its Aggregation Pathways Evaluated by Chemical Species Model Combined with Molecular Dynamics Calculations
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作者 YOSHII Noriyuki KOMORI Mika +3 位作者 KAWADA Shinji TAKABAYASHI Hiroaki FUJIMOTO Kazushi OKAZAKI Susumu 《物理化学学报》 SCIE CAS CSCD 北大核心 2018年第10期1163-1170,共8页
Surfactant molecules, when dispersed in solution, have been shown to spontaneously form aggregates. Our previous studies on molecular dynamics(MD) calculations have shown that ionic sodium dodecyl sulfate molecules qu... Surfactant molecules, when dispersed in solution, have been shown to spontaneously form aggregates. Our previous studies on molecular dynamics(MD) calculations have shown that ionic sodium dodecyl sulfate molecules quickly aggregated even when the aggregation number is small. The aggregation rate, however, decreased for larger aggregation numbers. In addition, studies have shown that micelle formation was not completed even after a 100 ns-long MD run(Chem. Phys. Lett. 2016, 646, 36). Herein, we analyze the free energy change of micelle formation based on chemical species model combined with molecular dynamics calculations. First, the free energy landscape of the aggregation, ?G_(i+j)^+, where two aggregates with sizes i and j associate to form the(i + j)-mer, was investigated using the free energy of micelle formation of the i-mer, G_i^+, which was obtained through MD calculations. The calculated ?G_(i+j)^+ was negative for all the aggregations where the sum of DS ions in the two aggregates was 60 or less. From the viewpoint of chemical equilibrium, aggregation to the stable micelle is desired. Further, the free energy profile along possible aggregation pathways was investigated, starting from small aggregates and ending with the complete thermodynamically stable micelles in solution. The free energy profiles, G(l, k), of the aggregates at l-th aggregation path and k-th state were evaluated by the formation free energy ∑_in_i( l,k)G_i^+ and the free energy of mixing ∑_in_i( l,k)k_BTln( n_i( l,k)/n( l,k)), where ni(l, k) is the number of i-mer in the system at the l-th i aggregation path and k-th state, with n(l,k)= ∑_n_i( l,k). All the aggregation pathways were obtained from the initial i state of 12 pentamers to the stable micelle with i = 60. All the calculated G(l, k) values monotonically decreased with increasing k. This indicates that there are no free energy barriers along the pathways. Hence, the slowdown is not due to the thermodynamic stability of the aggregates, but rather the kinetics that inhibit the association of the fragments. The time required for a collision between aggregates, one of the kinetic factors, was evaluated using the fast passage time, t_(FPT). The calculated t_(FPT) was about 20 ns for the aggregates with N = 31. Therefore, if aggregation is a diffusion-controlled process, it should be completed within the 100 ns-simulation. However, aggregation does not occur due to the free energy barrier between the aggregates, that is, the repulsive force acting on them. This may be caused by electrostatic repulsions produced by the overlap of the electric double layers, which are formed by the negative charge of the hydrophilic groups and counter sodium ions on the surface of the aggregates. 展开更多
关键词 Free energy CHANGE AGGREGATION pathway SDS MICELLE molecular dynamics calculation
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Molecular simulation study of the microstructures and properties of pyridinium ionic liquid[HPy][BF_(4)]mixed with acetonitrile
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作者 XU Jian-Qiang MA Zhao-Peng +2 位作者 CHENG Si LIU Zhi-Cong ZHU Guang-Lai 《原子与分子物理学报》 CAS 北大核心 2025年第4期27-32,共6页
The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this wo... The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this work.The following properties were determined:density,self-diffusion coefficient,excess molar volume,and radial distribution function.The results show that with an increase in the mole fraction of[HPy][BF_(4)],the self-diffusion coefficient decreases.Additionally,the excess molar volume initially decreases,reaches a minimum,and then increases.The rules of radial distribution functions(RDFs)of characteristic atoms are different.With increasing the mole fraction of[HPy][BF_(4)],the first peak of the RDFs of HA1-F decreases,while that of CT6-CT6 rises at first and then decreases.This indicates that the solvent molecules affect the polar and non-polar regions of[HPy][BF_(4)]differently. 展开更多
关键词 Pyridinium ionic liquids Thermodynamic properties molecular dynamics simulation Radial distribution functions
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Mechanical properties and thermal conductivity of pristine and functionalized carbon nanotube reinforced metallic glass composites:A molecular dynamics approach
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作者 Sumit Sharma S.K.Tiwari Sagar Shakya 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2021年第1期234-244,共11页
This work uses the molecular dynamics approach to study the effects of functionalization of carbon nanotubes(CNTs)on the mechanical properties of Cu64Zr36 metallic glass(MG).Three types of functional groups,carboxylic... This work uses the molecular dynamics approach to study the effects of functionalization of carbon nanotubes(CNTs)on the mechanical properties of Cu64Zr36 metallic glass(MG).Three types of functional groups,carboxylic,vinyl and ester were used.The effect of CNT volume fraction(Vf)and the number of functional groups attached to CNT,on the mechanical properties and thermal conductivity of CNT-MG composites was analysed using Biovia Materials Studio.At lower values of Vf(from 0 to 5%),the percentage increase in Young’s modulus was approximately 66%.As the value of Vf was increased further(from 5 to 12%),the rate of increase in Young’s modulus was reduced to 16%.The thermal conductivity was found to increase from 1.52 W/mK at Vf?0%to 5.88 W/mK at Vf?12%,thus giving an increase of approximately 286%.Functionalization of SWCNT reduced the thermal conductivity of the SWCNT-MG composites. 展开更多
关键词 molecular dynamics Carbon nanotube Metallic glass Mechanical properties Thermal conductivity
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MOLECULAR DYNAMICS SIMULATIONS OF FILLED AND EMPTY CAGE-LIKE WATER CLUSTERS IN LIQUID WATER AND THEIR SIGNIFICANCE TO GAS HYDRATE FORMATION MECHANISMS
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作者 GUO Guangjun,ZHANG Yigang and ZHAO Yajuan Institute of Geology and Geophysics,Chinese Academy of sciences Beijing 100029,Chinese 《化工学报》 EI CAS CSCD 北大核心 2003年第z1期62-66,共5页
Molecular dynamics simulations are performed to observe the evolutions of 512 and 51262 cage-like water clusters filled with or without a methane molecule immersed in bulk liquid water at 250 K and 230 K. The lifetime... Molecular dynamics simulations are performed to observe the evolutions of 512 and 51262 cage-like water clusters filled with or without a methane molecule immersed in bulk liquid water at 250 K and 230 K. The lifetimes of these clusters are calculated according to their Lindemann index δ (t) using the criteria of δ≥0.07. For both the filled and empty clusters, we find the dynamics of bulk water determines the lifetimes of cage-like water clusters, and that the lifetime of 512 62 cage-like cluster is the same as that of 512 cage-like cluster. Although the methane molecule indeed makes the filled cage-like cluster more stable than the empty one, the empty cage-like cluster still has chance to be long-lived compared with the filled clusters. These observations support the labile cluster hypothesis on the formation mechanisms of gas hydrates. 展开更多
关键词 like in time that were molecular dynamics SIMULATIONS OF FILLED AND EMPTY CAGE-LIKE WATER CLUSTERS IN LIQUID WATER AND THEIR SIGNIFICANCE TO GAS HYDRATE FORMATION MECHANISMS of cage GAS
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Molecular Dynamic Simulation for HMX/NTO Supramolecular Explosive 被引量:1
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作者 林鹤 朱顺官 +3 位作者 张琳 彭新华 李洪珍 陈阳 《Defence Technology(防务技术)》 SCIE EI CAS 2012年第3期161-166,共6页
Based on the crystal engineering, six models of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX)/3-nitro-1,2,4-triazol-5-one(NTO) supramolecular explosive were designed. The probable formation of HMX/NTO supramol... Based on the crystal engineering, six models of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX)/3-nitro-1,2,4-triazol-5-one(NTO) supramolecular explosive were designed. The probable formation of HMX/NTO supramolecular explosive was investigated by the molecular dynamic (MD) method. Interaction between oxygen atoms in HMX and hydrogen atoms in NTO or between hydrogen atoms in HMX and oxygen atoms in NTO were studied by the radial distribution function (RDF). It shows that there are strong hydrogen bonds and Van Der Waals forces between HMX and NTO, in which the hydrogen bonds between oxygen atoms in the NTO and hydrogen atoms in HMX are the main host-guest interactions. The distributions of bond length, bond angle and dihedral angle were simulated by MD. It shows that the structure of HMX is seriously distorted. The binding energies and X-ray powder diffraction (XRD) patterns were calculated on the basis of the final HMX/NTO supramolecular structures. The results show that the binding energies of six supramolecular models are E binding (1 1 1-) >E binding (1 0 0)>E binding (0 2 0)>E binding (random)>E binding (1 0 2-)>Ebinding (0 1 1), and the XRD patterns of six supramolecular models are quite different from pure HMX or NTO. Based on the investigation for growth morphology, binding energies and RDF, the model of HMX supercell substituted by NTO along the (1 1 1-) surface of HMX is easier to form. 展开更多
关键词 physical chemistry HMX NTO SUPRAMOLECULE molecular dynamics
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Thermodynamic analysis and dynamics simulation on reaction of Al_2O and AlCl_2 with carbon under vacuum 被引量:1
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作者 卢勇 周岳珍 +5 位作者 陈秀敏 李紫勇 郁青春 刘大春 杨斌 徐宝强 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第2期286-292,共7页
The feasibility study of the AlCl(g) generated by Al_2O-AlCl_2-C system under vacuum was carried out by thermodynamic analysis and CASTEP package of the Material Studio program which was based on density functional th... The feasibility study of the AlCl(g) generated by Al_2O-AlCl_2-C system under vacuum was carried out by thermodynamic analysis and CASTEP package of the Material Studio program which was based on density functional theory(DFT) formalism. Thermodynamic calculations indicate that Al Cl and CO molecules can be formed under conditions of temperature 1760 K and the pressure of 60 Pa. The interaction of Al_2O and AlCl_2 with C shows that the chemical adsorption of Al_2O and AlCl_2 does take place on C(001) crystal plane, and at the same time, new chemical bond is formed between Al atom in Al_2O and Cl atoms from one of the Al—Cl bonds in AlCl_2. The results, after 1.25 ps dynamics simulation, indicate that adsorbed Al Cl molecules are generated and CO molecule will be formed in this system, and they will escape from C(001) surface after a longer period of dynamic simulation time. It means that the reaction of Al_2O and AlCl_2 with C can be carried out under given constraint condition. 展开更多
关键词 Ab initio molecular dynamics carbothermic-chlorination (AlCl2) reaction THERMOdynamics INTERACTION Al2O
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Dynamics simulation of electrorheological suspensions in poiseuille flow field
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作者 朱石沙 罗成 +1 位作者 周杰 陈娜 《Journal of Central South University》 SCIE EI CAS 2008年第S1期234-238,共5页
Based on a modified Maxwell-Wagner model,molecular dynamics is carried out to simulate the structural changes of ER(electrorheological) suspensions in a poiseuille flow field.The simulation results show that the flow ... Based on a modified Maxwell-Wagner model,molecular dynamics is carried out to simulate the structural changes of ER(electrorheological) suspensions in a poiseuille flow field.The simulation results show that the flow assists in the collection of particles at the electrodes under a low pressure gradient,and the negative ER effect will show under a high pressure gradient.By analyzing the relationship curves of the shear stress and the pressure gradient in different relaxation time,it is found that for the same kind of ER suspensions materials,there is an optimal dielectric relaxation frequency. 展开更多
关键词 ELECTRORHEOLOGICAL SUSPENSIONS molecular dynamics pressure GRADIENT VALUE RELAXATION time.
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Molecular Dynamic Simulation of Kindlin F3 Domain with Integrin β3-tail
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作者 Yan Zhang Ying Fang Jianhua Wu 《医用生物力学》 EI CAS CSCD 北大核心 2019年第A01期160-160,共1页
Integrin activation,the transition from a low to a high affinity state,regulates the numerous cellular responses consequent to integrin engagement by extracellular matrix proteins.Kindlin proteins,play crucial roles i... Integrin activation,the transition from a low to a high affinity state,regulates the numerous cellular responses consequent to integrin engagement by extracellular matrix proteins.Kindlin proteins,play crucial roles in the integrin-signaling pathway by directly interacting with and activating integrins,which mediate the cell-extracellular matrix adhesion and signaling.As a widely distributed PTB domain protein and a major member of the kindlin family,kindlin2 interacts withβ3-tail,bridges talin-activated integrins to promote integrin aggregation,and enhances talin-induced integrin activation.Thus,kindlin2 is identified as a coactivator of integrins.Unlike talins,kindlin2 cannot directly alter the conformation of the integrin transmembrane helix and fail to activate integrin alone.Nevertheless,although it is widely accepted that kindlins and talins synergistically promote integrin activation,the underlying mechanism is unclear.Thus,the study of the force dissociation of the kindlin2/β3-tail complex and the conformation stabilization under different mechanical micro-environments should be of great significance for the further understanding of the structural basis of its synergistically activation of integrin.To reveal the molecular dynamics mechanism of interaction between kindlin2 andβ3-tail,we perform molecular dynamics(MD)simulations for this complex with different computing strategies interaction.In MD simulations,the available crystal structures of Kindlin-2/β3-tail complex(Protein Data Bank code 5XQ1)was downloaded from the PDB database.Two software packages,VMD for visualization and modeling and NAMD 2.13 for energy minimizations and MD simulations,were used here.The steadystate conformation of the complex was obtained from the equilibrium simulation.The dissociation event was observed by the constant velocity simulation,and the mechanical stability of the complex was observed by the constant force simulation.Our results showed that,during the equilibrium of the kindlin2-F3/β34ail complex,the residue MET612,LYS613 and TRP615 on the F3 domain of kindlin2 contributed to hydrogen-bonding with the corresponding residues onβ3 integrin.These bonds exhibit moderate or strong stability through steered molecular dynamics(SMD)simulation.During the constant velocity simulation,the complex exhibits a variety of unfolding pathways against tension applications,which are mainly distinguished by the disruption of hydrogen-bonds between the F3 domain a1/a2 helixes andβ1/β2 sheets.During the constant force simulation,the different phases of the composite force dissociation have different dissociation probabilities,which shows the biphasic force-dependent characteristics.And,the key residues in the pulling were recognized according not only to the number of interacting residue pairs,but also to their bond strength.Using molecular dynamics simulation,we showed the steady state of the kindlin2-F3/β3-tail complex under different tensile forces,and observe the dynamic process of molecular interaction.A possible underlying biophysical mechanism is that,the dissociation of Kindlin2-F3/β3-tail complex is biphasic force-dependent,and the conformations under different stretching states have different binding affinities.This study not only provides insights into the structural basis and mechanical regulation mechanisms of the kindlin/integrin interaction,in understanding in kindlin/integrin-related signaling in different cellular biological processes,but also provides new ideas for novel drug design and the treatment of related diseases. 展开更多
关键词 Kindlin2 molecular dynamics simulation STRUCTURE-FUNCTION RELATION MECHANOCHEMICAL coupling
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稠化剂组分对润滑脂摩擦性能的影响 被引量:1
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作者 潘伶 吴允李 +2 位作者 连金良 郑开魁 郭锦阳 《表面技术》 北大核心 2025年第5期83-92,共10页
目的研究稠化剂组分中二元酸和硼酸对润滑脂在摩擦副表面润滑性能的影响。方法分别建立具有正弦曲面凸峰的粗糙面边界润滑系统模型,以及光滑壁面的反应力场边界润滑系统模型,通过分子动力学模拟方法研究12-羟基硬脂酸/壬二酸润滑脂体系(... 目的研究稠化剂组分中二元酸和硼酸对润滑脂在摩擦副表面润滑性能的影响。方法分别建立具有正弦曲面凸峰的粗糙面边界润滑系统模型,以及光滑壁面的反应力场边界润滑系统模型,通过分子动力学模拟方法研究12-羟基硬脂酸/壬二酸润滑脂体系(A润滑脂)、12-羟基硬脂酸/十二烷二酸润滑脂体系(B润滑脂)和12-羟基硬脂酸/壬二酸/硼酸润滑脂体系(C润滑脂)的承载能力、抗剪切能力、摩擦性能,并对C润滑脂进行成键和摩擦化学反应膜分析。结合润滑脂的微摩擦磨损试验,揭示二元酸链长和硼酸对润滑脂摩擦性能的影响。结果在加压阶段,随着压力的增加,润滑脂密度增大,且分层现象越明显。当压力Pz=50MPa时,组分中含硼酸的C润滑脂在各处的密度均较小,表现出最佳的承载能力。在剪切过程中,C润滑脂始终将2个粗糙峰隔开,油膜不破裂,承载能力最高;含长链二元酸的B润滑脂和含硼酸的C润滑脂的最大应力相较于A润滑脂,分别降低了27.1%、57.1%。同时,C润滑脂的摩擦因数相对稳定,在0.075~0.095范围内波动,其均值为0.090,相较于B润滑脂和A润滑脂,分别降低了16.7%、22.2%,具有优良的力学性能。摩擦磨损结果表明,在稠化剂组分中添加硼酸后,润滑脂的理化性能得到显著提升,摩擦因数及均值分别为0.085~0.095和0.091,模拟结果与试验结果一致。结论相较于稠化剂中含短链二元酸的润滑脂,含长链二元酸的润滑脂表现出较好的抗剪切能力和摩擦性能。在稠化剂中添加硼酸后,稠化剂的结构得到强化,润滑脂表现出更为优异的抗磨减摩性能。这是因为在硼酸的作用下,润滑脂中的锂皂和硼酸基团不仅形成了配位键,而且能在固体壁面上形成摩擦反应膜,显著提高了润滑脂的物理化学性能。 展开更多
关键词 摩擦反应膜 稠化剂组分 摩擦性能 润滑脂 分子动力学
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单晶镍纳米切削材料去除行为与机理研究 被引量:1
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作者 田海兰 闫少华 +1 位作者 韩涛 闫海鹏 《制造技术与机床》 北大核心 2025年第1期157-165,共9页
单晶镍纳米尺度加工时的材料去除机理对实现其超精密加工尤为重要。为此,借助分子动力学仿真研究单晶镍纳米切削时的力热行为、表面/亚表面形成特征以及塑性变形机制以揭示材料去除机理。结果表明单晶镍纳米切削时,有序的镍原子在刀具... 单晶镍纳米尺度加工时的材料去除机理对实现其超精密加工尤为重要。为此,借助分子动力学仿真研究单晶镍纳米切削时的力热行为、表面/亚表面形成特征以及塑性变形机制以揭示材料去除机理。结果表明单晶镍纳米切削时,有序的镍原子在刀具挤压和剪切作用下以非晶结构的形式被去除,部分具有面心立方(face center cubic, FCC)结构的镍原子转变成密排六方(hexagonal close-packed, HCP)结构和非晶结构,主导了相变与非晶化;同时出现伯氏矢量分别为1/6<112>、1/3<100>、1/6<110>、1/3<111>以及1/2<110>的位错线。单晶镍纳米切削时的塑性变形机制为相变、非晶化和位错滑移。在切削过程中,由于几何条件与能量条件被同时满足,发生1/2<110>全位错转变为1/6<112>不全位错的位错反应。在切削力热的作用下,已加工亚表面出现了位错环、梯杆位错、棱住位错、V型位错、原子团簇和空位等缺陷结构。相比于(100)晶面和(110)晶面,沿(111)晶面切削有利于减小亚表面缺陷层深度。 展开更多
关键词 单晶镍 纳米切削 分子动力学 材料去除机理 塑性变形机制
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