In order to obtain liquefied products with higher yields of aromatic molecules to produce mesophase pitch,a good understanding of the relevant reaction mechanisms is required.Reactive molecular dynamics simulations we...In order to obtain liquefied products with higher yields of aromatic molecules to produce mesophase pitch,a good understanding of the relevant reaction mechanisms is required.Reactive molecular dynamics simulations were used to study the thermal reactions of pyrene,1-methylpyrene,7,8,9,10-tetrahydrobenzopyrene,and mixtures of pyrene with 1-octene,cyclohexene,or styrene.The reactant conversion rates,reaction rates,and product distributions were calculated and compared,and the mechanisms were analyzed and discussed.The results demonstrated that methyl and naphthenic structures in aromatics might improve the conversion rates of reactants in hydrogen transfer processes,but their steric hindrances prohibited the generation of high polymers.The naphthenic structures could generate more free radicals and presented a more obvious inhibition effect on the condensation of polymers compared with the methyl side chains.It was discovered that when different olefins were mixed with pyrene,1-octene primarily underwent pyrolysis reactions,whereas cyclohexene mainly underwent hydrogen transfer reactions with pyrene and styrene,mostly producing superconjugated biradicals through condensation reactions with pyrene.In the mixture systems,the olefins scattered aromatic molecules,hindering the formation of pyrene trimers and higher polymers.According to the reactive molecular dynamics simulations,styrene may enhance the yield of dimer and enable the controlled polycondensation of pyrene.展开更多
The condensation of DNA induced by spermine is studied by atomic force microscopy （AFM） and molecular dynamics （MD） simulation in this paper. In our experiments, an equivalent amount of multivalent cations is adde...The condensation of DNA induced by spermine is studied by atomic force microscopy （AFM） and molecular dynamics （MD） simulation in this paper. In our experiments, an equivalent amount of multivalent cations is added to the DNA solutions in different numbers of steps, and we find that the process of DNA condensation strongly depends on the speed of adding cations. That is, the slower the spermine cations are added, the slower the DNA aggregates. The MD and steered molecular dynamics （SMD） simulation results agree well with the experimental results, and the simulation data also show that the more steps of adding multivalent cations there are, the more compact the condensed DNA structure will be. This investigation can help us to control DNA condensation and understand the complicated structures of DNA--cation complexes.展开更多
A sensitive numerical simulation study is carded out to investigate the effects of condensation heating and surface fluxes on the development of a South China MCS that occurred during 23 - 24 May 1998. The results rev...A sensitive numerical simulation study is carded out to investigate the effects of condensation heating and surface fluxes on the development of a South China MCS that occurred during 23 - 24 May 1998. The results reveal the following： （1） Condensation heating plays an important role in the development of MCS. In every different stage, without condensation heating, MCS precipitation is significantly reduced, and quickly dissipates. （2） Condensation heating demonstrates most importantly during the early development stages of MCS vortex; as the vortex develops stronger, the condensation heating effects reduces. （3） By affecting the MCS development processes, condensation heating also influences the formation of MCS mesoscale environment structure features such as low-level jet （mLLJ）, upper-level divergence. （4） By changing the antecedent environmental circulation, the surface fluxes also play an important role in the development of MCS. Because of the surface heating, pressure declines over the heavy rainfall and MCS happening regions, which results in the intensification of southerly flows from the ocean along the South China coastline areas, and leads to the enhancement of horizontal convergence and increase of vapor amount in the lower layer. All of these make the atmosphere more unstable and more favorable for the convection.展开更多
Tunneling dynamics of multi-atomic molecules between any two multi-atomicmolecular Bose-Einstein condensates with Feshbach resonance is investigated. It is indicated thatthe tunneiing in the two Bose-Einstein condensa...Tunneling dynamics of multi-atomic molecules between any two multi-atomicmolecular Bose-Einstein condensates with Feshbach resonance is investigated. It is indicated thatthe tunneiing in the two Bose-Einstein condensates depends not only on the inter-molecular nonlinearinteractions and the initial number of molecule in these condensates, but also on the tunnelingcoupling between them. It is discovered that besides oscillating tunneling current between themulti-atomic molecular condensates, the nonlinear multi-atomic molecular tunneling dynamics sustainsa self-locked population imbalance: a macroscopic quantum self-trapping effect. The influence ofde-coherence caused by non-condensate molecule on the tunneling dynamics is studied. It is shownthat de-coherence suppresses the multi-atomic molecular tunneling.展开更多
We investigated the interaction between DNA and hexammine cobalt III [Co（NH3）6]3＋ by a simple molecular combing method and dynamic light scattering. The average extension of A- DNA-YOYO-1 complex is found to be 20....We investigated the interaction between DNA and hexammine cobalt III [Co（NH3）6]3＋ by a simple molecular combing method and dynamic light scattering. The average extension of A- DNA-YOYO-1 complex is found to be 20.9μm, about 30% longer than the contour length of the DNA in TE buffer （10 mmol/L Tris, 1 mmol/L EDTA, pH=8.0）, due to bis-intercalation of YOYO-1. A multivalent cation, hexammine cobalt, is used for DNA condensation. We find that the length of DNA-[Co（NH3）6]3＋ complexes decrease from 20.9 μm to 5.9μm as the concentration of the [Co（NH3）6]3＋ vary from 0 to 3 μmol/L. This observation provides a direct visualization of single DNA condensation induced by hexammine cobalt. The results from the molecular combing studies are supported by dynamic light scattering investigation, where the average hydrodynamic radius of the DNA complex decreases from 203.8 nm to 39.26 nm under the same conditions. It shows that the molecular combing method is feasible for quantitative conformation characterization of single bio-macromolecules.展开更多
We study tunneling dynamics of atomic group in two-species molecular Bose-Einstein condensates. It is shown that the tunneling of the atom group depends on not only the tunneling coupling constant between the atomic p...We study tunneling dynamics of atomic group in two-species molecular Bose-Einstein condensates. It is shown that the tunneling of the atom group depends on not only the tunneling coupling constant between the atomic pair molecular condensate and the three-atomic group molecular condensate, but also the inter-molecular nonlinear interactions and the initial number of atoms in these condensates. It is discovered that besides oscillating tunneling current between the atomic pair molecular condensate and the three-atomic group molecular condensate, the nonlinear atomic group tunneling dynamics sustains a self-maintained population imbalance: a macroscopic quantum self-trapping effect.展开更多
The Dabei gas field in the Kuqa Depression of the Tarim Basin is the most complex and deep continental condensate gas field in China. Comprehensive two-dimensional gas chromatography?time of flight mass spectrometer (...The Dabei gas field in the Kuqa Depression of the Tarim Basin is the most complex and deep continental condensate gas field in China. Comprehensive two-dimensional gas chromatography?time of flight mass spectrometer (GC×GC-TOFMS) analysis was conducted on five condensate oil samples from this field. The results show that the samples have n-alkane series in complete preservation and rich adamantanes. According to the methyladamantane index, the condensate oil is the product of the source rock with vitrinite reflectance (Ro) of 1.3%–1.6%. According to the gas maturity calculated through carbon isotope and vitrinite reflectance, the natural gas is corresponding to Ro of 1.3%–1.7%, reflecting that the natural gas and condensate oil are basically formed during the same period at the high maturity stage of source rock. The Dabei gas field has favorable geological conditions for hydrocarbon accumulation: thick salt rock in the Paleogene acts as a regional high-quality caprock directly overlying the high-quality sandstone reservoir of the Cretaceous, the coal source rocks have high hydrocarbon generation intensity and provide continuous oil and gas, and the subsalt thrust structures develop in rows with rich faults, providing migration pathways for oil and gas migration. These factors together controlled the formation of the Dabei gas field.展开更多
Tunneling dynamics of multi-atomic molecules between atomic and multi-atomic molecular Bose-Einstein condensates with Feshbach resonance is investigated.It is indicated that the tunneling in the two Bose-Einstein cond...Tunneling dynamics of multi-atomic molecules between atomic and multi-atomic molecular Bose-Einstein condensates with Feshbach resonance is investigated.It is indicated that the tunneling in the two Bose-Einstein condensates depends on not only the inter-atomic-molecular nonlinear interactions and the initial number of atoms in these condensates,but also the tunneling coupling between the atomic condensate and the multi-atomic molecular condensate.It is discovered that besides oscillating tunneling current between the atomic condensate and the multi-atomic molecular condensate,the nonlinear multi-atomic molecular tunneling dynamics sustains a self-locked population imbalance:a macroscopic quantum self-trapping effect.The influence of de-coherence caused by non-condensate atoms on the tunneling dynamics is studied.It is shown that de-coherence suppresses the multi-atomic molecular tunneling.Moreover,the conception of the molecular Bose-Einstein condensate,which is different from the conventional single-atomic Bose-Einstein condensate,is specially emphasized in this paper.展开更多
We achieve a highly degenerate and strongly interacting Fermi gas in a mixture of the two lowest hyperfine states of 6 Li by direct evaporative cooling in a high power crossed optical dipole trap. The trap is loaded f...We achieve a highly degenerate and strongly interacting Fermi gas in a mixture of the two lowest hyperfine states of 6 Li by direct evaporative cooling in a high power crossed optical dipole trap. The trap is loaded from a large atom number magneto-optical trap realized by a laser system of Z5-W intracavity-frequency-doubled light output at 671 nm. With this system, we also demonstrate the production of a molecular Bose-Einstein condensate （reBEC） of 6Li2, and observe the anisotropic expansion of Fermi gases in the so-called BEC-Bardeen-Cooper-Schrieffer crossover regime.展开更多
According to the definitions of molecular connectivity and hyper-Wiener index, a novel set of hyper-Wiener indexes （Dn, ^mDn） were defined and named as condensed extended hyper-Wiener index, the potential usefulness...According to the definitions of molecular connectivity and hyper-Wiener index, a novel set of hyper-Wiener indexes （Dn, ^mDn） were defined and named as condensed extended hyper-Wiener index, the potential usefulness of which in QSAR/QSPR is evaluated by its correlation with a number of C3-C8 alkanes as well as by a favorable comparison with models based on molecular connectivity index and overall Wiener index.展开更多
In order to study the donor ability of ferrocenylimines as directing ortho metalation group（DMG） to lithium alkylide to prepare planar chiral ferrocene, a series of ferrocenyl schiff bases were synthesized by new me...In order to study the donor ability of ferrocenylimines as directing ortho metalation group（DMG） to lithium alkylide to prepare planar chiral ferrocene, a series of ferrocenyl schiff bases were synthesized by new methods using molecular sieves（0.4nm） and AlCl3 as catalysts. The reaction periods were reduced using these two catalysts in contrast with Al2O3, which was a traditional method used in the literature. In addition, as an important feature of these schiff bases, we found that they were unstable as oils in air or when filtrated through silica gel, but were stable as solids. The structures of the new compounds were confirmed by IR, ^1H NMR and HRMS.展开更多
基金financially supported by the National Natural Science Foundation of China(Approval No.42172168).
文摘In order to obtain liquefied products with higher yields of aromatic molecules to produce mesophase pitch,a good understanding of the relevant reaction mechanisms is required.Reactive molecular dynamics simulations were used to study the thermal reactions of pyrene,1-methylpyrene,7,8,9,10-tetrahydrobenzopyrene,and mixtures of pyrene with 1-octene,cyclohexene,or styrene.The reactant conversion rates,reaction rates,and product distributions were calculated and compared,and the mechanisms were analyzed and discussed.The results demonstrated that methyl and naphthenic structures in aromatics might improve the conversion rates of reactants in hydrogen transfer processes,but their steric hindrances prohibited the generation of high polymers.The naphthenic structures could generate more free radicals and presented a more obvious inhibition effect on the condensation of polymers compared with the methyl side chains.It was discovered that when different olefins were mixed with pyrene,1-octene primarily underwent pyrolysis reactions,whereas cyclohexene mainly underwent hydrogen transfer reactions with pyrene and styrene,mostly producing superconjugated biradicals through condensation reactions with pyrene.In the mixture systems,the olefins scattered aromatic molecules,hindering the formation of pyrene trimers and higher polymers.According to the reactive molecular dynamics simulations,styrene may enhance the yield of dimer and enable the controlled polycondensation of pyrene.
基金supported by the National Natural Science Foundation of China (Grant Nos. 20974081, 20934004, 21174131, and 21104060)the Zhejiang Provincial Natural Science Foundation of China (Grant No. Y4110357)
文摘The condensation of DNA induced by spermine is studied by atomic force microscopy （AFM） and molecular dynamics （MD） simulation in this paper. In our experiments, an equivalent amount of multivalent cations is added to the DNA solutions in different numbers of steps, and we find that the process of DNA condensation strongly depends on the speed of adding cations. That is, the slower the spermine cations are added, the slower the DNA aggregates. The MD and steered molecular dynamics （SMD） simulation results agree well with the experimental results, and the simulation data also show that the more steps of adding multivalent cations there are, the more compact the condensed DNA structure will be. This investigation can help us to control DNA condensation and understand the complicated structures of DNA--cation complexes.
基金Project of Important Research Direction of Knowledge Infrastructure Building by the ChineseAcademy of Sciences (ZKCX2-WS-210) Research Project on Monitoring and Pre-warning Techniques of SevereWeather in the Pearl River Delta (2003DIB4J145)
文摘A sensitive numerical simulation study is carded out to investigate the effects of condensation heating and surface fluxes on the development of a South China MCS that occurred during 23 - 24 May 1998. The results reveal the following： （1） Condensation heating plays an important role in the development of MCS. In every different stage, without condensation heating, MCS precipitation is significantly reduced, and quickly dissipates. （2） Condensation heating demonstrates most importantly during the early development stages of MCS vortex; as the vortex develops stronger, the condensation heating effects reduces. （3） By affecting the MCS development processes, condensation heating also influences the formation of MCS mesoscale environment structure features such as low-level jet （mLLJ）, upper-level divergence. （4） By changing the antecedent environmental circulation, the surface fluxes also play an important role in the development of MCS. Because of the surface heating, pressure declines over the heavy rainfall and MCS happening regions, which results in the intensification of southerly flows from the ocean along the South China coastline areas, and leads to the enhancement of horizontal convergence and increase of vapor amount in the lower layer. All of these make the atmosphere more unstable and more favorable for the convection.
基金湖南省高校青年骨干教师培养基金，the Science Research Foundation of Educational Bureau of Hunan Province of China，湖南大学校科研和教改项目
文摘Tunneling dynamics of multi-atomic molecules between any two multi-atomicmolecular Bose-Einstein condensates with Feshbach resonance is investigated. It is indicated thatthe tunneiing in the two Bose-Einstein condensates depends not only on the inter-molecular nonlinearinteractions and the initial number of molecule in these condensates, but also on the tunnelingcoupling between them. It is discovered that besides oscillating tunneling current between themulti-atomic molecular condensates, the nonlinear multi-atomic molecular tunneling dynamics sustainsa self-locked population imbalance: a macroscopic quantum self-trapping effect. The influence ofde-coherence caused by non-condensate molecule on the tunneling dynamics is studied. It is shownthat de-coherence suppresses the multi-atomic molecular tunneling.
文摘We investigated the interaction between DNA and hexammine cobalt III [Co（NH3）6]3＋ by a simple molecular combing method and dynamic light scattering. The average extension of A- DNA-YOYO-1 complex is found to be 20.9μm, about 30% longer than the contour length of the DNA in TE buffer （10 mmol/L Tris, 1 mmol/L EDTA, pH=8.0）, due to bis-intercalation of YOYO-1. A multivalent cation, hexammine cobalt, is used for DNA condensation. We find that the length of DNA-[Co（NH3）6]3＋ complexes decrease from 20.9 μm to 5.9μm as the concentration of the [Co（NH3）6]3＋ vary from 0 to 3 μmol/L. This observation provides a direct visualization of single DNA condensation induced by hexammine cobalt. The results from the molecular combing studies are supported by dynamic light scattering investigation, where the average hydrodynamic radius of the DNA complex decreases from 203.8 nm to 39.26 nm under the same conditions. It shows that the molecular combing method is feasible for quantitative conformation characterization of single bio-macromolecules.
基金湖南省高校青年骨干教师培养基金，the Science Research Fund of Educational Bureau of Hunan Province of China，国家自然科学基金，国家重点基础研究发展计划(973计划)
文摘We study tunneling dynamics of atomic group in two-species molecular Bose-Einstein condensates. It is shown that the tunneling of the atom group depends on not only the tunneling coupling constant between the atomic pair molecular condensate and the three-atomic group molecular condensate, but also the inter-molecular nonlinear interactions and the initial number of atoms in these condensates. It is discovered that besides oscillating tunneling current between the atomic pair molecular condensate and the three-atomic group molecular condensate, the nonlinear atomic group tunneling dynamics sustains a self-maintained population imbalance: a macroscopic quantum self-trapping effect.
基金Supported by the China National Science and Technology Major Project(2016ZX05004-004)
文摘The Dabei gas field in the Kuqa Depression of the Tarim Basin is the most complex and deep continental condensate gas field in China. Comprehensive two-dimensional gas chromatography?time of flight mass spectrometer (GC×GC-TOFMS) analysis was conducted on five condensate oil samples from this field. The results show that the samples have n-alkane series in complete preservation and rich adamantanes. According to the methyladamantane index, the condensate oil is the product of the source rock with vitrinite reflectance (Ro) of 1.3%–1.6%. According to the gas maturity calculated through carbon isotope and vitrinite reflectance, the natural gas is corresponding to Ro of 1.3%–1.7%, reflecting that the natural gas and condensate oil are basically formed during the same period at the high maturity stage of source rock. The Dabei gas field has favorable geological conditions for hydrocarbon accumulation: thick salt rock in the Paleogene acts as a regional high-quality caprock directly overlying the high-quality sandstone reservoir of the Cretaceous, the coal source rocks have high hydrocarbon generation intensity and provide continuous oil and gas, and the subsalt thrust structures develop in rows with rich faults, providing migration pathways for oil and gas migration. These factors together controlled the formation of the Dabei gas field.
基金湖南省高校青年骨干教师培养基金，the Science Research Fund of Educational Bureau of Hunan Province of China
文摘Tunneling dynamics of multi-atomic molecules between atomic and multi-atomic molecular Bose-Einstein condensates with Feshbach resonance is investigated.It is indicated that the tunneling in the two Bose-Einstein condensates depends on not only the inter-atomic-molecular nonlinear interactions and the initial number of atoms in these condensates,but also the tunneling coupling between the atomic condensate and the multi-atomic molecular condensate.It is discovered that besides oscillating tunneling current between the atomic condensate and the multi-atomic molecular condensate,the nonlinear multi-atomic molecular tunneling dynamics sustains a self-locked population imbalance:a macroscopic quantum self-trapping effect.The influence of de-coherence caused by non-condensate atoms on the tunneling dynamics is studied.It is shown that de-coherence suppresses the multi-atomic molecular tunneling.Moreover,the conception of the molecular Bose-Einstein condensate,which is different from the conventional single-atomic Bose-Einstein condensate,is specially emphasized in this paper.
基金Supported by the National Natural Science Foundation of China under Grant No 11374101the Shanghai Pujiang Program under Grant No 13PJ1402500
文摘We achieve a highly degenerate and strongly interacting Fermi gas in a mixture of the two lowest hyperfine states of 6 Li by direct evaporative cooling in a high power crossed optical dipole trap. The trap is loaded from a large atom number magneto-optical trap realized by a laser system of Z5-W intracavity-frequency-doubled light output at 671 nm. With this system, we also demonstrate the production of a molecular Bose-Einstein condensate （reBEC） of 6Li2, and observe the anisotropic expansion of Fermi gases in the so-called BEC-Bardeen-Cooper-Schrieffer crossover regime.
文摘According to the definitions of molecular connectivity and hyper-Wiener index, a novel set of hyper-Wiener indexes （Dn, ^mDn） were defined and named as condensed extended hyper-Wiener index, the potential usefulness of which in QSAR/QSPR is evaluated by its correlation with a number of C3-C8 alkanes as well as by a favorable comparison with models based on molecular connectivity index and overall Wiener index.
文摘In order to study the donor ability of ferrocenylimines as directing ortho metalation group（DMG） to lithium alkylide to prepare planar chiral ferrocene, a series of ferrocenyl schiff bases were synthesized by new methods using molecular sieves（0.4nm） and AlCl3 as catalysts. The reaction periods were reduced using these two catalysts in contrast with Al2O3, which was a traditional method used in the literature. In addition, as an important feature of these schiff bases, we found that they were unstable as oils in air or when filtrated through silica gel, but were stable as solids. The structures of the new compounds were confirmed by IR, ^1H NMR and HRMS.
