As a prototypical high-energy-density reactive material system,metastable intermolecular composites(MICs)have attracted considerable interest owing to their customizable component configurations and interfacial archit...As a prototypical high-energy-density reactive material system,metastable intermolecular composites(MICs)have attracted considerable interest owing to their customizable component configurations and interfacial architectures.Nevertheless,their energy release characteristics are fundamentally constrained by the formation of condensed-phase products with elevated boiling points,thereby diminishing their efficacy in applications requiring rapid pressure generation or shock wave propagation.Herein,we demonstrate a molecular-level fluorination approach that enables oxygen substitution by fluorine within bismuth oxide crystalline frameworks,yielding ternary BixOyFz crystals with atomically precise F/O stoichiometric control through systematic solvent polarity engineering.This energetics system,designed through a multilevel regulation strategy,realizes stepwise redox reactions of Al–F and Al–O during energy release,with the partitioning between these redox pathways being precisely allocable through hierarchical regulation.Furthermore,the pre-ignition reaction(PIR)between BixOyFz and Al2O3(the inert passivation shell of Al)weakens the passivation layer,lowering the ignition threshold.The in situ generation of low-boiling-point AlF3 promotes rapid gas expansion,leading to significantly enhanced pressurization rates and deflagration wave velocities under confinement compared to conventional strategies.To evaluate energy output capabilities and validate potential safety-protection applications,the system successfully achieved instantaneous destruction of SD chips,enabling secure data erasure.This work establishes crystalline lattice fluorination as a generalized materials design strategy to transcend intrinsic limitations of MICs systems in component selection and reaction thermodynamics,providing new paradigms for adaptive energetic architectures and transient microelectromechanical applications.展开更多
The coupling reactions of methanol and long-chain alkanes(n-dodecane,n-tetradecane and n-hexadecane)over CHA-type molecular sieves were studied in a fixed bed reactor.Over SAPO-34 and SSZ-13,it was found that the indu...The coupling reactions of methanol and long-chain alkanes(n-dodecane,n-tetradecane and n-hexadecane)over CHA-type molecular sieves were studied in a fixed bed reactor.Over SAPO-34 and SSZ-13,it was found that the induction period of methanol conversion was shortened by the introduction of long-chain alkanes.However,the addition of long-chain alkanes had little influence on the product distribution.Polymethylbenzenes and the derivatives were the main retained species on spent SSZ-13 catalyst,while adamantanes were the main retained species on SAPO-34.This indicates that coking species formation was mainly related to the further transformation of long-chain alkane/methanol coupling products at acid sites of the molecular sieve.These findings provide valuable information of long chain alkanes conversion and methanol reaction behavior of induction period over small pore CHA molecular sieves.展开更多
As a key component of shale oil,petroleum fractions,and chemical products,the oxidative pyrolysis behavior of paraffin directly influences energy conversion efficiency and the direction of process optimization.A deep ...As a key component of shale oil,petroleum fractions,and chemical products,the oxidative pyrolysis behavior of paraffin directly influences energy conversion efficiency and the direction of process optimization.A deep understanding of its oxidative pyrolysis mechanism is crucial for addressing wax deposition in oil and gas extraction,enhancing product selectivity in cracking processes,and advancing novel clean fuel technologies.Traditional experimental methods face challenges in capturing transient free-radical reaction pathways at high temperatures,whereas molecular dynamics simulations offer a powerful approach to bridge the research gap in elucidating atomic-scale dynamic mechanisms.This database is constructed based on high-precision molecular dynamics simulations,comprising oxidative pyrolysis trajectory data for three paraffin models featuring different straight-chain hydrocarbon distributions within the temperature range of 2100-2500 K.The COMPASS force field was employed to optimize the initial structures,and the ReaxFF reactive force field was used to simulate the oxidative pyrolysis process.The database includes atomic trajectories,species evolution information,and reaction network analysis results for both heating and isothermal cracking processes,with a total data volume of approximately 141 GB(including 150000 atomic configuration frames).The data is stored in a hierarchical directory structure,supporting multi-scale oxidative pyrolysis mechanism studies and providing atomic-scale dynamic evidence for revealing carbon chain length effects and temperature sensitivity.展开更多
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
This paper discusses the influence of Sb/In ratio on the transport properties and crystal quality of the 200 nm InAs_(x)Sb_(1-x)thin film.The Sb content of InAs_(x)Sb_(1-x)thin film in all samples was verified by HRXR...This paper discusses the influence of Sb/In ratio on the transport properties and crystal quality of the 200 nm InAs_(x)Sb_(1-x)thin film.The Sb content of InAs_(x)Sb_(1-x)thin film in all samples was verified by HRXRD of the symmetrical 004 reflections and asymmetrical 115 reflections.The calculation results show that the Sb component was 0.6 in the InAs_(x)Sb_(1-x)thin film grown under the conditions of Sb/In ratio of 6 and As/In ratio of 3,which has the highest electron mobility(28560 cm^(2)/V·s)at 300 K.At the same time,the influence ofⅤ/Ⅲratio on the transport properties and crystal quality of Al_(0.2)In_(0.8)Sb/InAs_(x)Sb_(1-x)quantum well heterostructures also has been investigated.As a result,the Al_(0.2)In_(0.8)Sb/InAs_(0.4)Sb_(0.6)quantum well heterostructure with a channel thickness of 30 nm grown under the conditions of Sb/In ratio of 6 and As/In ratio of 3 has a maximum electron mobility of 28300 cm^(2)/V·s and a minimum RMS roughness of 0.68 nm.Through optimizing the growth conditions,our samples have higher electron mobility and smoother surface morphology.展开更多
Since the discovery of carbon dots(CDs)in 2004,the unique photoluminescence phenomenon of CDs has attracted widespread attention.However,the molecular weight of CDs has not been adequately quantified at present,due to...Since the discovery of carbon dots(CDs)in 2004,the unique photoluminescence phenomenon of CDs has attracted widespread attention.However,the molecular weight of CDs has not been adequately quantified at present,due to CDs are atomically imprecise and their molecular weight distribution is broad.In this paper,a series of Pluronic-modified CDs were prepared and the structure of the CDs was briefly analyzed.Subsequently,a molecular weight measurement method based on colligative properties was developed,and the correction coefficient in the algorithm was briefly analyzed.The calculated molecular weight was applied to the determination of surface adsorption capacity.This work provided a method for averaging the molecular weight of atomically imprecise particulate materials,which is expected to provide new opportunities in related fields.展开更多
Carbon nanotube formation exemplifies atomically precise self-assembly,where atomic interactions dynamically engineer nanoscale architectures with emergent properties that transcend classical material boundaries.Howev...Carbon nanotube formation exemplifies atomically precise self-assembly,where atomic interactions dynamically engineer nanoscale architectures with emergent properties that transcend classical material boundaries.However,elucidating the transient molecular intermediates remains a critical mechanistic frontier.This study investigates the atomic-scale nucleation process of single-walled carbon nanotubes(SWCNTs)from acetylene on iron(Fe)clusters,utilizing GFN(-x)TB-based nanoreactor molecular dynamics simulations.The simulations reveal a consistent nucleation pathway,regardless of iron cluster size(Fe_(13),Fe_(38),Fe_(55)),where the chemisorption and dissociation of acetylene molecules on the Fe clusters lead to the formation of C_(2)H and C_(2)intermediates.These species then undergo oligomerization,initiating the growth of carbon chains.As the chains cross-link and cyclize,five-membered carbon rings are preferentially formed,which eventually evolve into six-membered rings and more complex sp2-hybridized carbon networks,resembling the cap structures of nascent SWCNTs.Although the nucleation mechanism remains similar across all cluster sizes,larger clusters show enhanced catalytic activity,leading to higher molecular weight hydrocarbons and more extensive carbocyclic networks due to their higher density of active sites per reacting molecule.Crucially,the study highlights the role of C_(2)H as the key active species in the carbon network formation process.These findings offer critical insights into the initial stages of SWCNT nucleation,contributing to a deeper understanding of the mechanisms driving SWCNT growth and guiding the development of optimized synthetic strategies.展开更多
High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film ha...High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film has a tetragonal distortion with a c/a ratio of~0.98.The film exhibits exceptional stability in both aqueous and ambient conditions,which is a crucial factor for practical applications.Electrical transport reveals its metallic behavior with an upturn at low temperatures,which could be attributed to the Kondo effect originated from nitrogen vacancy-induced magnetic impurities.Room temperature exchange bias has been demonstrated in a MnN/CoFeB heterostructure,verifying the AFM ordering of MnN.Considering its high Néel temperature~650 K,superior stability,and low-cost,this work highlights the epitaxial MnN films as a promising candidate for AFM spintronic applications.展开更多
Background Unravelling the relationship between trichome density and resistance to jassids in upland cotton,nine parental lines,viz.MCU 5,CO 14,CO 17,TCH 1828,KC 2,KC 3,GISV 323,GTHV 15–34,and RHC 1409 were obtained ...Background Unravelling the relationship between trichome density and resistance to jassids in upland cotton,nine parental lines,viz.MCU 5,CO 14,CO 17,TCH 1828,KC 2,KC 3,GISV 323,GTHV 15–34,and RHC 1409 were obtained from the Tamilnadu Agricultural University.These genotypes were subjected to molecular analysis using 27 primers,merely the JESPR 154 primer amplifying a 150-bp fragment in genotypes exhibiting the pubescence.Result This finding validated the association between pubescence and jassid resistance.Further analysis revealed that resistant genotypes(KC 3,GTHV 15–34,GISV 323,and RHC 1409)exhibited significantly higher trichome densities and length compared with susceptible genotypes.These results stalwartly support the hypothesis that trichomes play a pivotal role in conferring resistance to jassids in upland cotton.Conclusion By breeding cotton varieties with increased trichome density and length,it is possible to reduce jassid infestations,thereby decreasing the reliance on chemical pesticides and promoting a more sustainable agricultural environment.展开更多
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
The feasibility of molecule markers＇ application in gene pyramiding has been proved,and obvious progresses in crop breeding have been made till now.Furthermore,different QTLs or molecular markers linked tightly to yi...The feasibility of molecule markers＇ application in gene pyramiding has been proved,and obvious progresses in crop breeding have been made till now.Furthermore,different QTLs or molecular markers linked tightly to yield,quality or resistance may be used for marker assisted selection.MAS will be applied widely in crop breeding due to the development of more gene-based markers and efficient quantitative trait locus（QTL） as well as lower cost marking systems.展开更多
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
Flax is a kind of worldwide fiber and oil crops, and it has a very important role in economic crop production in the world. With the development of molecular biology techniques, the research of flax molecular level ha...Flax is a kind of worldwide fiber and oil crops, and it has a very important role in economic crop production in the world. With the development of molecular biology techniques, the research of flax molecular level has a very big breakthrough. But, flax molecular biology researches are less reported due to the later starting. This paper summarized the latest research progress of molecular biology of flax, including molecular marker technology, construction of genetic map, gene engineering and omits researches, in order to provide the reference to understand the development and research status for flax molecular breeding researchers.展开更多
【Aim】The objective of this study is to characterize eight digestive carboxypeptidase genes in Anopheles sinensis,and to analyze their expression patterns before and post blood meal feeding.【Methods】The characteris...【Aim】The objective of this study is to characterize eight digestive carboxypeptidase genes in Anopheles sinensis,and to analyze their expression patterns before and post blood meal feeding.【Methods】The characteristics of eight digestive carboxypeptidase genes of An.sinensis were analyzed using bioinformatics methods,and their expression levels in different tissues at different developmental stages and in the midguts of female adults at different time points post blood meal feeding(PBM)were compared by semi-quantitative reverse transcription PCR and quantitative realtime PCR(qRT-PCR),respectively.【Results】Bioinformatics analysis indicated that of the eight carboxypeptidase genes,six genes encode carboxypeptidases A(AsCPA-I-AsCPA-VI)and two encode carboxypeptidases B(AsCPB-I and AsCPB-II).The expression of AsCPA-V was only detected in midguts and carcasses(whole mosquitoes minus midgut)of the 4th instar larvae,suggesting that it might have specific expression in larvae,while the other seven genes were simultaneously expressed in the 4th instar larvae and adults.After blood meal feeding,the expression levels of AsCPA-I,AsCPA-II,AsCPA-III,AsCPA-IV,AsCPA-VI,AsCPB-I and AsCPB-II in the midguts of female adults significantly changed,but their expression patterns were completely different,suggesting that the blood protein digestion is a complex process involving the coordinative expressions of multiple genes.The expression levels of AsCPA-I,AsCPA-III,AsCPA-IV,AsCPA-VI and AsCPB-II were all up-regulated and peaked at 24 h PBM.Especially,the expression level of AsCPA-VI rapidly increased at 3 h PBM,and peaked at 24 h PBM with^418fold induction,and that of AsCPB-II also increased by more than 40-fold at 24 h PBM,suggesting that they might be involved in blood protein digestion.However,the expression levels of AsCPA-II and AsCPB-I in midguts of female adults were significantly down-regulated after blood meal feeding.【Conclusion】Eight carboxypeptidase genes from An.sinensis were characterized.Among them,AsCPA-I,AsCPA-III,AsCPA-IV,AsCPA-VI and AsCPB-II are putatively involved in blood protein digestion;in particular,AsCPA-VI and AsCPB-II might play more important roles.Our results provide a basis for further study on the molecular mechanism of blood protein digestion in mosquitos as well as in An.sinensis.展开更多
In this reported study, the density functional theory(DFT) was used at the(U)B3LYP/6-311G(d,p) level to investigate the stabilization process of the nitrate ester plasticized polyether propellant(NEPE). Molecular simu...In this reported study, the density functional theory(DFT) was used at the(U)B3LYP/6-311G(d,p) level to investigate the stabilization process of the nitrate ester plasticized polyether propellant(NEPE). Molecular simulations were conducted of the reaction that generates NO_(2), the autocatalytic and aging reaction triggered by the NO_(2), and the nitrogen dioxide absorption reaction of the stabilizers during the propellent stabilization process. These simulations were derived using the transition-state theory(TST)and variational transition-state theory(VTST). The simulation results suggested that the stabilization of the NEPE propellant consisted of three stages. First, heat and NO_(2) were generated during the denitrification reaction of nitroglycerine(NG) and 1,2,4-butanetriol trinitrate(BTTN) in the NEPE propellant.Second, nitroso products were generated by the reactions of N-Methyl-4-nitroaniline(MNA) and 2-nitrodiphenylamine(2NDPA) with NO_(2). Third, the stabilizers were exhausted and the autocatalytic reaction of NG and BTTN and the aging reaction of polyethylene glycol(PEG) were triggered by the heat and NO_(2)generated in the first stage. By comparing the energy barriers of the various reactions, it was found that the NO_(2)generated from the denitrification reaction significantly reduced the reaction energy barrier to 105.56-126.32 kJ/mol, also increased the reaction rate constant, and decreased the thermal stability and energetic properties of the NEPE propellant. In addition, the NO_(2)also weakened the mechanical properties of the NEPE propellant by attacking the-CH2groups and the O atoms in the PEG molecular chain. The energy barriers of the reactions of MNA and 2NDPA with NO_(2)(94.61-133.61 k J/mol) were lower than those of the autocatalytic and decomposition reactions of NG, BTTN, and the aging reactions of PEG(160.30-279.46 kJ/mol). This indicated that, by eliminating NO_(2), the stabilizer in the NEPE propellant can effectively prevent NO_(2)from reacting with the NG, BTTN, and PEG in the NEPE propellant. Consequently, this would help maintain the energy and mechanical properties of the NEPE propellant, thereby improving its thermal stability.展开更多
In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process,a one month thermal aging test was carried out at70C with ...In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process,a one month thermal aging test was carried out at70C with pre-strain of 0%,3%,6%and 9%,respectively.The low-field1 H NMR and stress relaxation modulus tests were carried out for HTPB coating at different aging stages.The stress relaxation model considering the molecular chains was proposed according to the changes of crosslinking chain and dangling chain of HTPB coating during pre-strain aging.The results showed that with the increase of aging time,the decay rate of transverse relaxation curve became faster,the transverse relaxation time decreased,the value of combined parameter q Mrl increased,the proportion of crosslinking chain decreased,while the proportion of dangling chain increased.Moreover,the stress relaxation modulus increased,the crosslinking network structure of HTPB coating became denser and the degree of crosslinking increased.At the initial aging stage,the pre-strain will destroy the crosslinking network structure of HTPB coating to a certain extent.With the increase of aging time,the effect of pre-strain will gradually weaken and the influence of aging on materials will gradually increase.The correlations between the stress relaxation model considering the molecular chains and the test results were more than 0.9950,which can accurately describe the stress relaxation modulus of HTPB coating during the pre-strain thermal aging process.展开更多
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
基金supported by the National Natural Science Foundation of China,China(Grant No.22305100,No.22405104)the Hubei Provincial International Science and Technology Cooperation Program Project(Grant No.2023EHA014)+4 种基金the National Foreign Experts Program(Grant No.Y20240022,H20240275)the Hubei Natural Science Foundation(Grant No.2025AFB460)the Hubei Provincial Department of Education Scientific Research Project(Grant No.F2023033,Q20234414)the Wuhan Natural Science Foundation Exploration Project(Chenguang Program)(Grant No.2025040601020173)the Jianghan University Scientific Research Startup Fund(Grant No.PBSKL-2022-QD-08,No.PBSKL-2024-QD-03).
文摘As a prototypical high-energy-density reactive material system,metastable intermolecular composites(MICs)have attracted considerable interest owing to their customizable component configurations and interfacial architectures.Nevertheless,their energy release characteristics are fundamentally constrained by the formation of condensed-phase products with elevated boiling points,thereby diminishing their efficacy in applications requiring rapid pressure generation or shock wave propagation.Herein,we demonstrate a molecular-level fluorination approach that enables oxygen substitution by fluorine within bismuth oxide crystalline frameworks,yielding ternary BixOyFz crystals with atomically precise F/O stoichiometric control through systematic solvent polarity engineering.This energetics system,designed through a multilevel regulation strategy,realizes stepwise redox reactions of Al–F and Al–O during energy release,with the partitioning between these redox pathways being precisely allocable through hierarchical regulation.Furthermore,the pre-ignition reaction(PIR)between BixOyFz and Al2O3(the inert passivation shell of Al)weakens the passivation layer,lowering the ignition threshold.The in situ generation of low-boiling-point AlF3 promotes rapid gas expansion,leading to significantly enhanced pressurization rates and deflagration wave velocities under confinement compared to conventional strategies.To evaluate energy output capabilities and validate potential safety-protection applications,the system successfully achieved instantaneous destruction of SD chips,enabling secure data erasure.This work establishes crystalline lattice fluorination as a generalized materials design strategy to transcend intrinsic limitations of MICs systems in component selection and reaction thermodynamics,providing new paradigms for adaptive energetic architectures and transient microelectromechanical applications.
基金Supported by National Natural Science Foundation of China(21991093)。
文摘The coupling reactions of methanol and long-chain alkanes(n-dodecane,n-tetradecane and n-hexadecane)over CHA-type molecular sieves were studied in a fixed bed reactor.Over SAPO-34 and SSZ-13,it was found that the induction period of methanol conversion was shortened by the introduction of long-chain alkanes.However,the addition of long-chain alkanes had little influence on the product distribution.Polymethylbenzenes and the derivatives were the main retained species on spent SSZ-13 catalyst,while adamantanes were the main retained species on SAPO-34.This indicates that coking species formation was mainly related to the further transformation of long-chain alkane/methanol coupling products at acid sites of the molecular sieve.These findings provide valuable information of long chain alkanes conversion and methanol reaction behavior of induction period over small pore CHA molecular sieves.
基金Supported by Natural Science Foundation of Shanxi Province (202203021221219)Research on the Construction of Scientific and Technological Innovation Think Tank of Shanxi Association for Science and Technology (KXKT202542)Planning Project under Commerce Statistical Society of China (2025STY122)。
文摘As a key component of shale oil,petroleum fractions,and chemical products,the oxidative pyrolysis behavior of paraffin directly influences energy conversion efficiency and the direction of process optimization.A deep understanding of its oxidative pyrolysis mechanism is crucial for addressing wax deposition in oil and gas extraction,enhancing product selectivity in cracking processes,and advancing novel clean fuel technologies.Traditional experimental methods face challenges in capturing transient free-radical reaction pathways at high temperatures,whereas molecular dynamics simulations offer a powerful approach to bridge the research gap in elucidating atomic-scale dynamic mechanisms.This database is constructed based on high-precision molecular dynamics simulations,comprising oxidative pyrolysis trajectory data for three paraffin models featuring different straight-chain hydrocarbon distributions within the temperature range of 2100-2500 K.The COMPASS force field was employed to optimize the initial structures,and the ReaxFF reactive force field was used to simulate the oxidative pyrolysis process.The database includes atomic trajectories,species evolution information,and reaction network analysis results for both heating and isothermal cracking processes,with a total data volume of approximately 141 GB(including 150000 atomic configuration frames).The data is stored in a hierarchical directory structure,supporting multi-scale oxidative pyrolysis mechanism studies and providing atomic-scale dynamic evidence for revealing carbon chain length effects and temperature sensitivity.
文摘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.
基金Supported by the Natural Science Basic Research Program of Shaanxi Province(2023-JC-QN-0758)Shaanxi University of Science and Technology Research Launch Project(2020BJ-26)Doctoral Research Initializing Fund of Hebei University of Science and Technology,China(1181476).
文摘This paper discusses the influence of Sb/In ratio on the transport properties and crystal quality of the 200 nm InAs_(x)Sb_(1-x)thin film.The Sb content of InAs_(x)Sb_(1-x)thin film in all samples was verified by HRXRD of the symmetrical 004 reflections and asymmetrical 115 reflections.The calculation results show that the Sb component was 0.6 in the InAs_(x)Sb_(1-x)thin film grown under the conditions of Sb/In ratio of 6 and As/In ratio of 3,which has the highest electron mobility(28560 cm^(2)/V·s)at 300 K.At the same time,the influence ofⅤ/Ⅲratio on the transport properties and crystal quality of Al_(0.2)In_(0.8)Sb/InAs_(x)Sb_(1-x)quantum well heterostructures also has been investigated.As a result,the Al_(0.2)In_(0.8)Sb/InAs_(0.4)Sb_(0.6)quantum well heterostructure with a channel thickness of 30 nm grown under the conditions of Sb/In ratio of 6 and As/In ratio of 3 has a maximum electron mobility of 28300 cm^(2)/V·s and a minimum RMS roughness of 0.68 nm.Through optimizing the growth conditions,our samples have higher electron mobility and smoother surface morphology.
文摘Since the discovery of carbon dots(CDs)in 2004,the unique photoluminescence phenomenon of CDs has attracted widespread attention.However,the molecular weight of CDs has not been adequately quantified at present,due to CDs are atomically imprecise and their molecular weight distribution is broad.In this paper,a series of Pluronic-modified CDs were prepared and the structure of the CDs was briefly analyzed.Subsequently,a molecular weight measurement method based on colligative properties was developed,and the correction coefficient in the algorithm was briefly analyzed.The calculated molecular weight was applied to the determination of surface adsorption capacity.This work provided a method for averaging the molecular weight of atomically imprecise particulate materials,which is expected to provide new opportunities in related fields.
基金supported by the National Key R&D Program of China(2022YFA1604100)the National Natural Science Foundation of China(22302220,22372187,1972157,21972160,22402218)+2 种基金the National Science Fund for Distinguished Young Scholars of China(22225206)the Fundamental Research Program of Shanxi Province(202203021222403)the Youth Innovation Promotion Association CAS(2020179)。
文摘Carbon nanotube formation exemplifies atomically precise self-assembly,where atomic interactions dynamically engineer nanoscale architectures with emergent properties that transcend classical material boundaries.However,elucidating the transient molecular intermediates remains a critical mechanistic frontier.This study investigates the atomic-scale nucleation process of single-walled carbon nanotubes(SWCNTs)from acetylene on iron(Fe)clusters,utilizing GFN(-x)TB-based nanoreactor molecular dynamics simulations.The simulations reveal a consistent nucleation pathway,regardless of iron cluster size(Fe_(13),Fe_(38),Fe_(55)),where the chemisorption and dissociation of acetylene molecules on the Fe clusters lead to the formation of C_(2)H and C_(2)intermediates.These species then undergo oligomerization,initiating the growth of carbon chains.As the chains cross-link and cyclize,five-membered carbon rings are preferentially formed,which eventually evolve into six-membered rings and more complex sp2-hybridized carbon networks,resembling the cap structures of nascent SWCNTs.Although the nucleation mechanism remains similar across all cluster sizes,larger clusters show enhanced catalytic activity,leading to higher molecular weight hydrocarbons and more extensive carbocyclic networks due to their higher density of active sites per reacting molecule.Crucially,the study highlights the role of C_(2)H as the key active species in the carbon network formation process.These findings offer critical insights into the initial stages of SWCNT nucleation,contributing to a deeper understanding of the mechanisms driving SWCNT growth and guiding the development of optimized synthetic strategies.
文摘High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film has a tetragonal distortion with a c/a ratio of~0.98.The film exhibits exceptional stability in both aqueous and ambient conditions,which is a crucial factor for practical applications.Electrical transport reveals its metallic behavior with an upturn at low temperatures,which could be attributed to the Kondo effect originated from nitrogen vacancy-induced magnetic impurities.Room temperature exchange bias has been demonstrated in a MnN/CoFeB heterostructure,verifying the AFM ordering of MnN.Considering its high Néel temperature~650 K,superior stability,and low-cost,this work highlights the epitaxial MnN films as a promising candidate for AFM spintronic applications.
文摘Background Unravelling the relationship between trichome density and resistance to jassids in upland cotton,nine parental lines,viz.MCU 5,CO 14,CO 17,TCH 1828,KC 2,KC 3,GISV 323,GTHV 15–34,and RHC 1409 were obtained from the Tamilnadu Agricultural University.These genotypes were subjected to molecular analysis using 27 primers,merely the JESPR 154 primer amplifying a 150-bp fragment in genotypes exhibiting the pubescence.Result This finding validated the association between pubescence and jassid resistance.Further analysis revealed that resistant genotypes(KC 3,GTHV 15–34,GISV 323,and RHC 1409)exhibited significantly higher trichome densities and length compared with susceptible genotypes.These results stalwartly support the hypothesis that trichomes play a pivotal role in conferring resistance to jassids in upland cotton.Conclusion By breeding cotton varieties with increased trichome density and length,it is possible to reduce jassid infestations,thereby decreasing the reliance on chemical pesticides and promoting a more sustainable agricultural environment.
基金supported by the fellowship of China Postdoctoral Science Foundation(Grant No.2021TQ0267)。
文摘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.
基金Supported by National 863 Plan (2006AA100108-4-9)
文摘The feasibility of molecule markers＇ application in gene pyramiding has been proved,and obvious progresses in crop breeding have been made till now.Furthermore,different QTLs or molecular markers linked tightly to yield,quality or resistance may be used for marker assisted selection.MAS will be applied widely in crop breeding due to the development of more gene-based markers and efficient quantitative trait locus（QTL） as well as lower cost marking systems.
基金supported by the National Natural Science Foundation of China(Grant No.11832006).
文摘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.
基金Supported by the National Natural Science Foundation of China(31401451)National Agro-industry Technology Research System for Crops of Bast and Leaf Fiber(CARS-19-S03)
文摘Flax is a kind of worldwide fiber and oil crops, and it has a very important role in economic crop production in the world. With the development of molecular biology techniques, the research of flax molecular level has a very big breakthrough. But, flax molecular biology researches are less reported due to the later starting. This paper summarized the latest research progress of molecular biology of flax, including molecular marker technology, construction of genetic map, gene engineering and omits researches, in order to provide the reference to understand the development and research status for flax molecular breeding researchers.
文摘【Aim】The objective of this study is to characterize eight digestive carboxypeptidase genes in Anopheles sinensis,and to analyze their expression patterns before and post blood meal feeding.【Methods】The characteristics of eight digestive carboxypeptidase genes of An.sinensis were analyzed using bioinformatics methods,and their expression levels in different tissues at different developmental stages and in the midguts of female adults at different time points post blood meal feeding(PBM)were compared by semi-quantitative reverse transcription PCR and quantitative realtime PCR(qRT-PCR),respectively.【Results】Bioinformatics analysis indicated that of the eight carboxypeptidase genes,six genes encode carboxypeptidases A(AsCPA-I-AsCPA-VI)and two encode carboxypeptidases B(AsCPB-I and AsCPB-II).The expression of AsCPA-V was only detected in midguts and carcasses(whole mosquitoes minus midgut)of the 4th instar larvae,suggesting that it might have specific expression in larvae,while the other seven genes were simultaneously expressed in the 4th instar larvae and adults.After blood meal feeding,the expression levels of AsCPA-I,AsCPA-II,AsCPA-III,AsCPA-IV,AsCPA-VI,AsCPB-I and AsCPB-II in the midguts of female adults significantly changed,but their expression patterns were completely different,suggesting that the blood protein digestion is a complex process involving the coordinative expressions of multiple genes.The expression levels of AsCPA-I,AsCPA-III,AsCPA-IV,AsCPA-VI and AsCPB-II were all up-regulated and peaked at 24 h PBM.Especially,the expression level of AsCPA-VI rapidly increased at 3 h PBM,and peaked at 24 h PBM with^418fold induction,and that of AsCPB-II also increased by more than 40-fold at 24 h PBM,suggesting that they might be involved in blood protein digestion.However,the expression levels of AsCPA-II and AsCPB-I in midguts of female adults were significantly down-regulated after blood meal feeding.【Conclusion】Eight carboxypeptidase genes from An.sinensis were characterized.Among them,AsCPA-I,AsCPA-III,AsCPA-IV,AsCPA-VI and AsCPB-II are putatively involved in blood protein digestion;in particular,AsCPA-VI and AsCPB-II might play more important roles.Our results provide a basis for further study on the molecular mechanism of blood protein digestion in mosquitos as well as in An.sinensis.
基金the support provided by the School of Physics and Optoelectronic Engineering of Ludong University。
文摘In this reported study, the density functional theory(DFT) was used at the(U)B3LYP/6-311G(d,p) level to investigate the stabilization process of the nitrate ester plasticized polyether propellant(NEPE). Molecular simulations were conducted of the reaction that generates NO_(2), the autocatalytic and aging reaction triggered by the NO_(2), and the nitrogen dioxide absorption reaction of the stabilizers during the propellent stabilization process. These simulations were derived using the transition-state theory(TST)and variational transition-state theory(VTST). The simulation results suggested that the stabilization of the NEPE propellant consisted of three stages. First, heat and NO_(2) were generated during the denitrification reaction of nitroglycerine(NG) and 1,2,4-butanetriol trinitrate(BTTN) in the NEPE propellant.Second, nitroso products were generated by the reactions of N-Methyl-4-nitroaniline(MNA) and 2-nitrodiphenylamine(2NDPA) with NO_(2). Third, the stabilizers were exhausted and the autocatalytic reaction of NG and BTTN and the aging reaction of polyethylene glycol(PEG) were triggered by the heat and NO_(2)generated in the first stage. By comparing the energy barriers of the various reactions, it was found that the NO_(2)generated from the denitrification reaction significantly reduced the reaction energy barrier to 105.56-126.32 kJ/mol, also increased the reaction rate constant, and decreased the thermal stability and energetic properties of the NEPE propellant. In addition, the NO_(2)also weakened the mechanical properties of the NEPE propellant by attacking the-CH2groups and the O atoms in the PEG molecular chain. The energy barriers of the reactions of MNA and 2NDPA with NO_(2)(94.61-133.61 k J/mol) were lower than those of the autocatalytic and decomposition reactions of NG, BTTN, and the aging reactions of PEG(160.30-279.46 kJ/mol). This indicated that, by eliminating NO_(2), the stabilizer in the NEPE propellant can effectively prevent NO_(2)from reacting with the NG, BTTN, and PEG in the NEPE propellant. Consequently, this would help maintain the energy and mechanical properties of the NEPE propellant, thereby improving its thermal stability.
基金supported by the National Defense Pre-Research Projects[grant number ZS2015070132A12002]。
文摘In order to accurately describe the transverse relaxation characteristic and stress relaxation modulus of HTPB coating during pre-strain thermal aging process,a one month thermal aging test was carried out at70C with pre-strain of 0%,3%,6%and 9%,respectively.The low-field1 H NMR and stress relaxation modulus tests were carried out for HTPB coating at different aging stages.The stress relaxation model considering the molecular chains was proposed according to the changes of crosslinking chain and dangling chain of HTPB coating during pre-strain aging.The results showed that with the increase of aging time,the decay rate of transverse relaxation curve became faster,the transverse relaxation time decreased,the value of combined parameter q Mrl increased,the proportion of crosslinking chain decreased,while the proportion of dangling chain increased.Moreover,the stress relaxation modulus increased,the crosslinking network structure of HTPB coating became denser and the degree of crosslinking increased.At the initial aging stage,the pre-strain will destroy the crosslinking network structure of HTPB coating to a certain extent.With the increase of aging time,the effect of pre-strain will gradually weaken and the influence of aging on materials will gradually increase.The correlations between the stress relaxation model considering the molecular chains and the test results were more than 0.9950,which can accurately describe the stress relaxation modulus of HTPB coating during the pre-strain thermal aging process.
基金Sponsored by the National Natural Science Foundation of China (61106078)NUST Research Funding (2011ZDJH28)
文摘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.
