Amorphous forms of C will first be compared and contrasted with amorphous Si, the differences in chemical bonding being emphasized in relation to atomic structure. After a brief discussion of ordered layers of graphit...Amorphous forms of C will first be compared and contrasted with amorphous Si, the differences in chemical bonding being emphasized in relation to atomic structure. After a brief discussion of ordered layers of graphite and of BN, some attention will be focused on BN cages and polymers and on C nanotubes. Finally properties of Na metal clusters will be discussed, including fission of such charged clusters展开更多
Inclusion bodies(IBs)of respiratory syncytial virus(RSV)are formed by liquid-liquid phase separation(LLPS)and contain internal structures termed“IB-associated granules”(IBAGs),where anti-termination factor M2-1 and ...Inclusion bodies(IBs)of respiratory syncytial virus(RSV)are formed by liquid-liquid phase separation(LLPS)and contain internal structures termed“IB-associated granules”(IBAGs),where anti-termination factor M2-1 and viral mRNAs are concentrated.However,the mechanism of IBAG formation and the physiological function of IBAGs are unclear.Here,we found that the internal structures of RSV IBs are actual M2-1-free viral messenger ribonucleoprotein(mRNP)condensates formed by secondary LLPS.Mechanistically,the RSV nucleoprotein(N)and M2-1 interact with and recruit PABP to IBs,promoting PABP to bind viral mRNAs transcribed in IBs by RNArecognition motif and drive secondary phase separation.Furthermore,PABP-eIF4G1 interaction regulates viral mRNP condensate composition,thereby recruiting specific translation initiation factors(eIF4G1,eIF4E,eIF4A,eIF4B and eIF4H)into the secondary condensed phase to activate viral mRNAs for ribosomal recruitment.Our study proposes a novel LLPS-regulated translation mechanism during viral infection and a novel antiviral strategy via targeting on secondary condensed phase.展开更多
MPHPB was prepared from melamine,phenylphosphonic acid and boric acid,and its flame retardant effect in PE was investigated.Compared to the intermediate product(melamine phenyl hypophosphite(MPHP)),the residual char i...MPHPB was prepared from melamine,phenylphosphonic acid and boric acid,and its flame retardant effect in PE was investigated.Compared to the intermediate product(melamine phenyl hypophosphite(MPHP)),the residual char increased from 17.9% of MPHP to 41.2% of MPHPB at 800℃.The limiting oxygen index(LOI)of PE/20%MPHPB is 23.6%,which reaches V-0 rating.After the addition of 20%MPHPB,the total heat release(THR),peak heat release rate(pK-HRR),and average effective thermal combustion rates(av-EHC)of PE decreased.Additionally,characterizations including the pyrolysis gas chromatography-mass spectrometry(Py-GC-MS),scanning electron microscopy(SEM),raman spectroscopy test(LRS)and fourier transform infrared(FT-IR)were taken to investigate the flame retardant mechanism,and the results show that MPHPB plays roles in both gas and condensed phases.展开更多
To enhance the process of phenyltrichlorosilane synthesis using gas phase condensation, a series of chloralkanes were introduced. The influence of temperature and chloralkane amount on the synthesis was studied based ...To enhance the process of phenyltrichlorosilane synthesis using gas phase condensation, a series of chloralkanes were introduced. The influence of temperature and chloralkane amount on the synthesis was studied based on the product distribution from a tubular reactor. The promoting effect of chloralkane addition was mainly caused by the chloralkane radicals generated by the dissociation of C–Cl bond. The promoting effect of the chloromethane with more chlorine atoms was better than those with less chlorine atoms. Intermediates detected from the reactions with isoprene and bromobenzene demonstrated that both trichlorosilyl radical and dichlorosilylene existed in the reaction system in the presence of chloralkanes. A detailed reaction scheme was proposed.展开更多
Methylphenyldichlorosilane(MPDS, CH3C6H5 SiC l2) is an important silicone monomer for the synthesis of highperformance polymethylphenylsiloxane polymers. In this work, the mechanism of the synthesis of MPDS from methy...Methylphenyldichlorosilane(MPDS, CH3C6H5 SiC l2) is an important silicone monomer for the synthesis of highperformance polymethylphenylsiloxane polymers. In this work, the mechanism of the synthesis of MPDS from methyldichlorosilane and chlorobenzene by gas phase condensation was studied, and a kinetic model with 35 species and 58 elementary reactions was established. Experiments were carried out in a tubular reactor under a wide range of reaction conditions. The calculated mole fractions of the reactants and products were in a good agreement with the experimental results. A mechanism of the insertion of chloromethylsilylene into the C\Cl bond of chlorobenzene was proposed, which was proved to be the main pathway of MPDS production. The established kinetic model can be used in design and optimization of the industrial reactor for MPDS synthesis.展开更多
We study the influence of the phase noises of far detuning single frequency lasers on the lifetime of Bose-Einstein condensation（BEC）of^（87）Rb in an optical dipole trap.As a comparison,we shine a continuous-wave s...We study the influence of the phase noises of far detuning single frequency lasers on the lifetime of Bose-Einstein condensation（BEC）of^（87）Rb in an optical dipole trap.As a comparison,we shine a continuous-wave singlefrequency Ti：sapphire laser,an external-cavity diode laser and a phase-locked diode laser on BEC.We measure the heating and lifetime of BEC in two different hyperfine states：｜F=2,m_F=2〉and｜F=1,m_F=1〉.Due to the narrow linewidth and small phase noise,the continuous-wave single-frequency Ti：sapphire laser has less influence on the lifetime of^（87）Rb BEC than the external-cavity diode laser.To reduce the phase noise of the external-cavity diode laser,we use an optical phase-locked loop for the external-cavity diode laser to be locked on a Ti：sapphire laser.The lifetime of BEC is increased when applfying the phase-Jocked diode laser in contrast with the external-cavity diode laser.展开更多
Five novel bis—(N—alkyl—N,N—dimethyl ammoni(?)n)polyethyleneglyool ether salts prepared by our previously reported proced(?)e show high catalytic efficiency in the condensation of 1,4—diacetyl— 2,5—piperazinedi...Five novel bis—(N—alkyl—N,N—dimethyl ammoni(?)n)polyethyleneglyool ether salts prepared by our previously reported proced(?)e show high catalytic efficiency in the condensation of 1,4—diacetyl— 2,5—piperazinedione and aldehydes at both higher and lower temperature even in lower concentration.They al so show catalytic selectivity at lower temperature.展开更多
We study the dynamics of a two-mode Bose flubbard model with phase dissipation, based on the master equation. An analytical solution is presented with nonzero asymmetry and phase noise. The effects of asymmetry and ph...We study the dynamics of a two-mode Bose flubbard model with phase dissipation, based on the master equation. An analytical solution is presented with nonzero asymmetry and phase noise. The effects of asymmetry and phase noise play a contrasting role in the dynamics. The asymmetry makes the oscillation fast, while phase noise enlarges the period. The conditions for the cases of fast decay and oscillation are presented. As a possible application, the dynamical evolution of the population for cold atomic gases with synthetic gauge interaction, which can be understood as two-mode dynamics in momentum space, is predicted.展开更多
Accurate prediction of molecular polarizability is essential for understanding electrical,optical,and dielectric properties of materials.Traditional quantum mechanical(QM)methods,though precise for small systems,are c...Accurate prediction of molecular polarizability is essential for understanding electrical,optical,and dielectric properties of materials.Traditional quantum mechanical(QM)methods,though precise for small systems,are computationally prohibitive for large-scale systems.In this work,we proposed an efficient approach for calculating molecular polarizability of condensed-phase systemsby embedding atomic polarizability constraints into the tensorial neuroevolution potential(TNEP)framework.Using n-heneicosane as a benchmark,a training data set was constructed frommolecular clusters truncated from the bulk systems.Atomic polarizabilities derived from semi-empirical QM calculations were integrated as training constraints for its balance of computational efficiency and physical interpretability.The constrained TNEP model demonstrated improved accuracy in predicting molecular polarizabilities for larger clusters and condensed-phase systems,attributed to the model’s refined ability to properly partition molecular polarizabilities into atomic contributions across systems with diverse configurational features.Results highlight the potential of the TNEP model with atomic polarizability constraint as a generalizable strategy to enhance the scalability and transferability of other atom-centered machine learning-based polarizability models,offering a promising solution for simulating large-scale systems with high data efficiency.展开更多
We classify condensable𝐸E_(2)-algebras in a modular tensor category C up to 2-Morita equivalence.Physically,this classification provides an explicit criterion to determine when distinct condensable𝐸E_(...We classify condensable𝐸E_(2)-algebras in a modular tensor category C up to 2-Morita equivalence.Physically,this classification provides an explicit criterion to determine when distinct condensable𝐸E_(2)-algebras yield the same condensed topological phase under a two-dimensional anyon condensation process.The relations between different condensable algebras can be translated into their module categories,interpreted physically as gapped domain walls in topological orders.As concrete examples,we interpret the categories of quantum doubles of finite groups and examples beyond group symmetries.Our framework fully elucidates the interplay among condensable𝐸E_(1)-algebras in C,condensable𝐸E_(2)-algebras in C up to 2-Morita equivalence,and Lagrangian algebras in C⊠C.展开更多
The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties o...The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties of alumina particles while the study considering the presence of aluminum is lacking.In addition,the thermal radiation inside the SRM with consideration of the participating particles is seldom studied.In this work,the multiscale method of predicting the thermal environment inside SRMs is established from the particle radiation at microscale to the twophase flow and heat transfer at macroscale.The effective gray radiative properties of individual particles(alumina,aluminum,and hybrid alumina/aluminum)and particles cloud are investigated with the Mie theory and approximate method.Then a numerical method for predicting the thermal environment inside SRMs with considering particle radiation is established and applied in a subscale motor.The convective and radiative heat flux distributions along inner wall of motor are obtained,and it is found that the heat transfer in the combustion chamber is dominated by thermal radiation and the radiative heat flux is essentially a constant of 5.6–6.8 MW/m^(2).The convective heat transfer plays a dominant role in the nozzle and the heat flux reaches the maximum value of 11.2 MW/m^(2) near the throat.As the combustion efficiency of aluminum drops,the radiative heat flux remains unchanged in most regions and increases slightly along the diverging section wall of the nozzle.展开更多
Boron has high mass and volume calorific values,but it is difficult to ignite and has low combustion efficiency.This literature review summarizes the strategies that are used to solve the above-mentioned problems,whic...Boron has high mass and volume calorific values,but it is difficult to ignite and has low combustion efficiency.This literature review summarizes the strategies that are used to solve the above-mentioned problems,which include coatings of boron by using fluoride compounds,energetic composites,metal fuels,and metal oxides.Coating techniques include recrystallization,dual-solvent,phase transfer,electrospinning,etc.As one of the effective coating agents,the fluorine compounds can react with the oxide shell of boron powder.In comparison,the energetic composites can effectively improve the flame temperature of boron powder and enhance the evaporation efficiency of oxide film as a condensed product.Metals and metal oxides would react with boron powder to form metal borides with a lower ignition point,which could reduce its ignition temperature.展开更多
Coherent control has been achieved in atoms and small molecules in gas phase during the past few decades.An intriguing demonstration of coherent control is a so-called“dark pulse”that cancels 2-photon transition pro...Coherent control has been achieved in atoms and small molecules in gas phase during the past few decades.An intriguing demonstration of coherent control is a so-called“dark pulse”that cancels 2-photon transition probabilities despite exposing the target to the full power spectrum of transform-limited laser pulses.However,for larger functional molecules in condensed phase at room temperature,ensemble measurements do typically not allow exerting full control over competing pathways due to the unavoidable influence of the surrounding(mostly complex)environment.Here,we demonstrate room-temperature coherent control exploiting a nonresonant 2-photon transition into a higher excited state of single conjugated polymer chains embedded in a disordered matrix,including proof-of-principle experiments on bulk films.To manipulate the 2-photon transition probability,we exploit complex pulse sequences,created by a systematically varied cosinusoidal spectral phase applied to the excitation laser spectrum.For single molecules,the phase-dependent response varies from molecule to molecule,which reflects the spectral heterogeneity(position,linewidth)of their 2-photon transitions.These data indicate that coherent control of single molecules requires optimization of parameters for each individual molecule.The experimental data are reproduced by a simple model that allows to directly retrieve the 2-photon absorption spectrum of each single molecule.Our coherent-control approach is a powerful and robust way to obtain spectral characteristics of higher excited states of single molecules and to manipulate the excited-state dynamics in condensed phase at room temperature.It holds the potential to be useful for the characterization of complex organic functional materials.展开更多
First-principles electron dynamics calculations can be applied in the investigation of a wide range of ultrafast phenomena in attosecond physics.They offer unique microscopic insight into light-induced ultrafast pheno...First-principles electron dynamics calculations can be applied in the investigation of a wide range of ultrafast phenomena in attosecond physics.They offer unique microscopic insight into light-induced ultrafast phenomena in both gas and condensed phases of matter,and thus,they are apowerful tool to develop our understanding of the physics of attosecond phenomena.We specifically review techniques employing time-dependent density functional theory(TDDFT)for investigating attosecond and strong-field phenomena.First,we describe this theoretical framework that enables the modeling of perturbative and non-perturbative electron dynamics in materials,including atoms,molecules,and solids.We then discuss its application to attosecond experiments,focusing on the reconstruction of attosecond beating by interference of two-photon transitions(RABBIT)measurements.Wealso briefly review first-principles calculations of optical properties of solids with TDDFT in the linear response regime and their extension to calculations of transient optical properties of solids in non-equilibrium phases,by simulating experimental pump-probe setups.We further demonstrate the application of TDDFT simulation to high-order harmonic generation in solids.First-principles calculations have predictive power,and hence they can be utilized to design future experiments to explore nonequilibrium and nonlinear ultrafast phenomena in matter and characterize and control metastable light-induced quantum states.展开更多
This study presents a predictive model for condensed-phase heats of formation of metal-containing energetic complexes(MCECs)and energetic metal-organic frameworks(EMOFs),leveraging a dataset of 148 compounds.Using ele...This study presents a predictive model for condensed-phase heats of formation of metal-containing energetic complexes(MCECs)and energetic metal-organic frameworks(EMOFs),leveraging a dataset of 148 compounds.Using elemental composition,triazole rings,and metal presence,the model achieves high accuracy(R^(2)>0.94,mean absolute error(MAE)≈390 kJ/mol)for screening high-energy materials.It outperforms prior methods,particularly for polycyclic systems,offering a practical tool for safer design and risk assessment in defense and industrial applications.展开更多
The effect of potash as a nondurable finish on the flammability of 100% cotton fabric （plain 180 g/m^2） was investigated. The bone-drled weighed fabrics were dipped into suitable concentrations of potash, with a vol...The effect of potash as a nondurable finish on the flammability of 100% cotton fabric （plain 180 g/m^2） was investigated. The bone-drled weighed fabrics were dipped into suitable concentrations of potash, with a volume of 100 mL at 20-2℃. The impregnation was followed by means of squeeze rolls and drying at 110 ℃. The samples were then reweighed with analytical precision. After conditioning overnight by using our ＂vertical flame tester＂ the optimum add-on values to impart flame-retardancy to cotton fabric was determined and expressed by 0.80 g of potash per 100 g fabric to be an efficient addition. Thermogravimetric analysis of pure cotton, treated cotton with potash at its optimum efficiency for donation of flame-retardancy into cotton fabric was fulfilled and the thermograms were compared and commented. The effectiveness of this hydroxide was attributed to the heat dissipation by the remaining consumed material during the combustion. The results obtained are in favor of ＂Dust or Wall Effect Theory＂.展开更多
文摘Amorphous forms of C will first be compared and contrasted with amorphous Si, the differences in chemical bonding being emphasized in relation to atomic structure. After a brief discussion of ordered layers of graphite and of BN, some attention will be focused on BN cages and polymers and on C nanotubes. Finally properties of Na metal clusters will be discussed, including fission of such charged clusters
基金supported by the grants from National Key R&D Program of China(2021YFC2300702 and 2021YFC2300200)the Hubei Provincial Natural Science Foundation of China(2021CFB364)+1 种基金the National Natural Science Foundation of China(82130064,81825015,U22A20337 and 32000119)the Key Biosafety Science and Technology Program of Hubei Jiangxia Laboratory(JXBS001).
文摘Inclusion bodies(IBs)of respiratory syncytial virus(RSV)are formed by liquid-liquid phase separation(LLPS)and contain internal structures termed“IB-associated granules”(IBAGs),where anti-termination factor M2-1 and viral mRNAs are concentrated.However,the mechanism of IBAG formation and the physiological function of IBAGs are unclear.Here,we found that the internal structures of RSV IBs are actual M2-1-free viral messenger ribonucleoprotein(mRNP)condensates formed by secondary LLPS.Mechanistically,the RSV nucleoprotein(N)and M2-1 interact with and recruit PABP to IBs,promoting PABP to bind viral mRNAs transcribed in IBs by RNArecognition motif and drive secondary phase separation.Furthermore,PABP-eIF4G1 interaction regulates viral mRNP condensate composition,thereby recruiting specific translation initiation factors(eIF4G1,eIF4E,eIF4A,eIF4B and eIF4H)into the secondary condensed phase to activate viral mRNAs for ribosomal recruitment.Our study proposes a novel LLPS-regulated translation mechanism during viral infection and a novel antiviral strategy via targeting on secondary condensed phase.
基金Funded by the Natural Science Foundation of Guangdong(Nos.2014A030313241,2014B090901068,and 2016A010103003)。
文摘MPHPB was prepared from melamine,phenylphosphonic acid and boric acid,and its flame retardant effect in PE was investigated.Compared to the intermediate product(melamine phenyl hypophosphite(MPHP)),the residual char increased from 17.9% of MPHP to 41.2% of MPHPB at 800℃.The limiting oxygen index(LOI)of PE/20%MPHPB is 23.6%,which reaches V-0 rating.After the addition of 20%MPHPB,the total heat release(THR),peak heat release rate(pK-HRR),and average effective thermal combustion rates(av-EHC)of PE decreased.Additionally,characterizations including the pyrolysis gas chromatography-mass spectrometry(Py-GC-MS),scanning electron microscopy(SEM),raman spectroscopy test(LRS)and fourier transform infrared(FT-IR)were taken to investigate the flame retardant mechanism,and the results show that MPHPB plays roles in both gas and condensed phases.
文摘To enhance the process of phenyltrichlorosilane synthesis using gas phase condensation, a series of chloralkanes were introduced. The influence of temperature and chloralkane amount on the synthesis was studied based on the product distribution from a tubular reactor. The promoting effect of chloralkane addition was mainly caused by the chloralkane radicals generated by the dissociation of C–Cl bond. The promoting effect of the chloromethane with more chlorine atoms was better than those with less chlorine atoms. Intermediates detected from the reactions with isoprene and bromobenzene demonstrated that both trichlorosilyl radical and dichlorosilylene existed in the reaction system in the presence of chloralkanes. A detailed reaction scheme was proposed.
文摘Methylphenyldichlorosilane(MPDS, CH3C6H5 SiC l2) is an important silicone monomer for the synthesis of highperformance polymethylphenylsiloxane polymers. In this work, the mechanism of the synthesis of MPDS from methyldichlorosilane and chlorobenzene by gas phase condensation was studied, and a kinetic model with 35 species and 58 elementary reactions was established. Experiments were carried out in a tubular reactor under a wide range of reaction conditions. The calculated mole fractions of the reactants and products were in a good agreement with the experimental results. A mechanism of the insertion of chloromethylsilylene into the C\Cl bond of chlorobenzene was proposed, which was proved to be the main pathway of MPDS production. The established kinetic model can be used in design and optimization of the industrial reactor for MPDS synthesis.
基金Supported by the National Key Research and Development Program of China under Grant Nos 2016YFA0301600 and 2016YFA0301602the National Natural Science Foundation of China under Grant Nos 11234008,11474188 and 11704234the Fund for Shanxi'1331 Project'Key Subjects Construction
文摘We study the influence of the phase noises of far detuning single frequency lasers on the lifetime of Bose-Einstein condensation（BEC）of^（87）Rb in an optical dipole trap.As a comparison,we shine a continuous-wave singlefrequency Ti：sapphire laser,an external-cavity diode laser and a phase-locked diode laser on BEC.We measure the heating and lifetime of BEC in two different hyperfine states：｜F=2,m_F=2〉and｜F=1,m_F=1〉.Due to the narrow linewidth and small phase noise,the continuous-wave single-frequency Ti：sapphire laser has less influence on the lifetime of^（87）Rb BEC than the external-cavity diode laser.To reduce the phase noise of the external-cavity diode laser,we use an optical phase-locked loop for the external-cavity diode laser to be locked on a Ti：sapphire laser.The lifetime of BEC is increased when applfying the phase-Jocked diode laser in contrast with the external-cavity diode laser.
文摘Five novel bis—(N—alkyl—N,N—dimethyl ammoni(?)n)polyethyleneglyool ether salts prepared by our previously reported proced(?)e show high catalytic efficiency in the condensation of 1,4—diacetyl— 2,5—piperazinedione and aldehydes at both higher and lower temperature even in lower concentration.They al so show catalytic selectivity at lower temperature.
基金Supported by the National Natural Science Foundation of China under Grant No 11374197the Program for Changjiang Scholars and Innovative Research Team in Universities of China under Grant No IRT13076the Hundred Talent Program of Shanxi Province
文摘We study the dynamics of a two-mode Bose flubbard model with phase dissipation, based on the master equation. An analytical solution is presented with nonzero asymmetry and phase noise. The effects of asymmetry and phase noise play a contrasting role in the dynamics. The asymmetry makes the oscillation fast, while phase noise enlarges the period. The conditions for the cases of fast decay and oscillation are presented. As a possible application, the dynamical evolution of the population for cold atomic gases with synthetic gauge interaction, which can be understood as two-mode dynamics in momentum space, is predicted.
基金supported by “Pioneer” and “Leading Goose” R&D Program of Zhejiang (grant number: 2023C01182)the National Natural Science Foundation of China (grant numbers: 22408314, 22178299, and 51933009)Nan Xu would like to thank the financial support provided by the Startup Funds of the Institute of Zhejiang University-Quzhou.
文摘Accurate prediction of molecular polarizability is essential for understanding electrical,optical,and dielectric properties of materials.Traditional quantum mechanical(QM)methods,though precise for small systems,are computationally prohibitive for large-scale systems.In this work,we proposed an efficient approach for calculating molecular polarizability of condensed-phase systemsby embedding atomic polarizability constraints into the tensorial neuroevolution potential(TNEP)framework.Using n-heneicosane as a benchmark,a training data set was constructed frommolecular clusters truncated from the bulk systems.Atomic polarizabilities derived from semi-empirical QM calculations were integrated as training constraints for its balance of computational efficiency and physical interpretability.The constrained TNEP model demonstrated improved accuracy in predicting molecular polarizabilities for larger clusters and condensed-phase systems,attributed to the model’s refined ability to properly partition molecular polarizabilities into atomic contributions across systems with diverse configurational features.Results highlight the potential of the TNEP model with atomic polarizability constraint as a generalizable strategy to enhance the scalability and transferability of other atom-centered machine learning-based polarizability models,offering a promising solution for simulating large-scale systems with high data efficiency.
基金supported by Research Grants Council(RGC),University Grants Committee(UGC)of Hong Kong(ECS No.24304722)。
文摘We classify condensable𝐸E_(2)-algebras in a modular tensor category C up to 2-Morita equivalence.Physically,this classification provides an explicit criterion to determine when distinct condensable𝐸E_(2)-algebras yield the same condensed topological phase under a two-dimensional anyon condensation process.The relations between different condensable algebras can be translated into their module categories,interpreted physically as gapped domain walls in topological orders.As concrete examples,we interpret the categories of quantum doubles of finite groups and examples beyond group symmetries.Our framework fully elucidates the interplay among condensable𝐸E_(1)-algebras in C,condensable𝐸E_(2)-algebras in C up to 2-Morita equivalence,and Lagrangian algebras in C⊠C.
基金supported by the Innovative Talents Support Plan of China Postdoctoral Foundation(No.BX20180244)National Natural Science Foundation of China(No.51825604)the Fundamental Research Funds for the Central Universities of China(No.xjj2018029)。
文摘The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties of alumina particles while the study considering the presence of aluminum is lacking.In addition,the thermal radiation inside the SRM with consideration of the participating particles is seldom studied.In this work,the multiscale method of predicting the thermal environment inside SRMs is established from the particle radiation at microscale to the twophase flow and heat transfer at macroscale.The effective gray radiative properties of individual particles(alumina,aluminum,and hybrid alumina/aluminum)and particles cloud are investigated with the Mie theory and approximate method.Then a numerical method for predicting the thermal environment inside SRMs with considering particle radiation is established and applied in a subscale motor.The convective and radiative heat flux distributions along inner wall of motor are obtained,and it is found that the heat transfer in the combustion chamber is dominated by thermal radiation and the radiative heat flux is essentially a constant of 5.6–6.8 MW/m^(2).The convective heat transfer plays a dominant role in the nozzle and the heat flux reaches the maximum value of 11.2 MW/m^(2) near the throat.As the combustion efficiency of aluminum drops,the radiative heat flux remains unchanged in most regions and increases slightly along the diverging section wall of the nozzle.
基金funded by Shaanxi Provincial Key Research and Development Program of China(Grant No.2021ZDLGY11)partially supported by NSAF Project of China(Grant No.U2030202)。
文摘Boron has high mass and volume calorific values,but it is difficult to ignite and has low combustion efficiency.This literature review summarizes the strategies that are used to solve the above-mentioned problems,which include coatings of boron by using fluoride compounds,energetic composites,metal fuels,and metal oxides.Coating techniques include recrystallization,dual-solvent,phase transfer,electrospinning,etc.As one of the effective coating agents,the fluorine compounds can react with the oxide shell of boron powder.In comparison,the energetic composites can effectively improve the flame temperature of boron powder and enhance the evaporation efficiency of oxide film as a condensed product.Metals and metal oxides would react with boron powder to form metal borides with a lower ignition point,which could reduce its ignition temperature.
基金supported by the China Scholarship Council(no.202006170068).
文摘Coherent control has been achieved in atoms and small molecules in gas phase during the past few decades.An intriguing demonstration of coherent control is a so-called“dark pulse”that cancels 2-photon transition probabilities despite exposing the target to the full power spectrum of transform-limited laser pulses.However,for larger functional molecules in condensed phase at room temperature,ensemble measurements do typically not allow exerting full control over competing pathways due to the unavoidable influence of the surrounding(mostly complex)environment.Here,we demonstrate room-temperature coherent control exploiting a nonresonant 2-photon transition into a higher excited state of single conjugated polymer chains embedded in a disordered matrix,including proof-of-principle experiments on bulk films.To manipulate the 2-photon transition probability,we exploit complex pulse sequences,created by a systematically varied cosinusoidal spectral phase applied to the excitation laser spectrum.For single molecules,the phase-dependent response varies from molecule to molecule,which reflects the spectral heterogeneity(position,linewidth)of their 2-photon transitions.These data indicate that coherent control of single molecules requires optimization of parameters for each individual molecule.The experimental data are reproduced by a simple model that allows to directly retrieve the 2-photon absorption spectrum of each single molecule.Our coherent-control approach is a powerful and robust way to obtain spectral characteristics of higher excited states of single molecules and to manipulate the excited-state dynamics in condensed phase at room temperature.It holds the potential to be useful for the characterization of complex organic functional materials.
基金supported by JSPS KAKENHI Grant Numbers JP20K14382 and JP21H01842the Cluster of Excellence 'CUI: Advanced Imaging of Matter'- EXC 2056 - project ID 390715994+5 种基金SFB-925 "Light induced dynamics and control of correlated quantum systems" – project 170620586 of the Deutsche Forschungsgemeinschaft (DFG)the Max Planck-New York City Center for Non-Equilibrium Quantum PhenomenaThis work was also supported by MEXT Promotion of Development of a Joint Usage/ Research System Project: Coalition of Universities for Research Excellence Program (CURE) Grant Number JPMXP1323015474We also acknowledge support from the Marie Sk{\l}odowska- Curie Doctoral Network TIMES, grant No. 101118915, and SPARKLE grant No. 101169225the Italian Ministry of University and Research (MUR) under the PRIN 2022 Grant No 2022PX279E_003Next Generation EUPartenariato Esteso NQSTI - Spoke 2 (THENCE-PE00000023). The Flatiron Institute is a division of the Simons Foundation. This work used computational resources of the HPC systems at the Max Planck Computing and Data Facility (MPCDF), and the Fujitsu PRIMERGY CX400M1/CX2550M5 (Oakbridge-CX) at the Information Technology Center, the University of Tokyo through the HPCI System Research Project (Project ID:hp220112).
文摘First-principles electron dynamics calculations can be applied in the investigation of a wide range of ultrafast phenomena in attosecond physics.They offer unique microscopic insight into light-induced ultrafast phenomena in both gas and condensed phases of matter,and thus,they are apowerful tool to develop our understanding of the physics of attosecond phenomena.We specifically review techniques employing time-dependent density functional theory(TDDFT)for investigating attosecond and strong-field phenomena.First,we describe this theoretical framework that enables the modeling of perturbative and non-perturbative electron dynamics in materials,including atoms,molecules,and solids.We then discuss its application to attosecond experiments,focusing on the reconstruction of attosecond beating by interference of two-photon transitions(RABBIT)measurements.Wealso briefly review first-principles calculations of optical properties of solids with TDDFT in the linear response regime and their extension to calculations of transient optical properties of solids in non-equilibrium phases,by simulating experimental pump-probe setups.We further demonstrate the application of TDDFT simulation to high-order harmonic generation in solids.First-principles calculations have predictive power,and hence they can be utilized to design future experiments to explore nonequilibrium and nonlinear ultrafast phenomena in matter and characterize and control metastable light-induced quantum states.
文摘This study presents a predictive model for condensed-phase heats of formation of metal-containing energetic complexes(MCECs)and energetic metal-organic frameworks(EMOFs),leveraging a dataset of 148 compounds.Using elemental composition,triazole rings,and metal presence,the model achieves high accuracy(R^(2)>0.94,mean absolute error(MAE)≈390 kJ/mol)for screening high-energy materials.It outperforms prior methods,particularly for polycyclic systems,offering a practical tool for safer design and risk assessment in defense and industrial applications.
文摘The effect of potash as a nondurable finish on the flammability of 100% cotton fabric （plain 180 g/m^2） was investigated. The bone-drled weighed fabrics were dipped into suitable concentrations of potash, with a volume of 100 mL at 20-2℃. The impregnation was followed by means of squeeze rolls and drying at 110 ℃. The samples were then reweighed with analytical precision. After conditioning overnight by using our ＂vertical flame tester＂ the optimum add-on values to impart flame-retardancy to cotton fabric was determined and expressed by 0.80 g of potash per 100 g fabric to be an efficient addition. Thermogravimetric analysis of pure cotton, treated cotton with potash at its optimum efficiency for donation of flame-retardancy into cotton fabric was fulfilled and the thermograms were compared and commented. The effectiveness of this hydroxide was attributed to the heat dissipation by the remaining consumed material during the combustion. The results obtained are in favor of ＂Dust or Wall Effect Theory＂.
