Two kinds of heavy oils were fractionated into eight fractions by Liquid-Solid Adsorption Chromatography,respectively,and samples were collected to measure properties.According to the elemental analysis,molecular weig...Two kinds of heavy oils were fractionated into eight fractions by Liquid-Solid Adsorption Chromatography,respectively,and samples were collected to measure properties.According to the elemental analysis,molecular weight and 1H-NMR data,average molecular structures of polycyclic aromatic and heavy resin were constructed with improved Brown-Ladner(B-L)method and several corrections.And then,the most stable conformations of polycyclic aromatic and heavy resin in vacuum and toluene solution were obtained by molecular dynamic simulation,and the molecular size was gotten via the radius of gyration analysis.The results showed that the radius of gyration of polycyclic aromatic and heavy resin was 0.55-0.70 nm in vacuum and 0.60-0.90 nm in toluene solution.With molecular weight increasing,the molecular size in vacuum and toluene solution also increased.Due to the swelling behavior of solvent,the alkyl side chains of heavy oil molecule in solution were more stretched.Thus,the molecular size in toluene solution was larger than that in vacuum.展开更多
The effects of the concentration of sodium chloride in an aqueous solution（cNacl and the temperature on the molecular size of poly（sulfobetaine methacrylate）（PSBMA） were studied via viscometry and dynamic light s...The effects of the concentration of sodium chloride in an aqueous solution（cNacl and the temperature on the molecular size of poly（sulfobetaine methacrylate）（PSBMA） were studied via viscometry and dynamic light scattering（DLS）. The morphology of single-chain PSBMA was determined by atomic force microscopy（AFM）. The results demonstrate that the hydrodynamic diameter of PSBMA can be expressed as a continuous function of CNaCl, with the molecular size of PSBMA increasing and eventually approaching an asymptotic value with increasing CNaCl. The molecular size of PSBMA at a lower CNaCI（0.04 mol/L） increases with increasing temperature, which is the opposite of the temperature effect at a higher CNaCl（2.0 mol/L）. Therefore, the internal structure of PSBMA chains in solutions with a low salt concentration differs from that in solutions with a high salt concentration. In addition, the morphology of single chains of PSBMA appears to be spherical, containing 89% void space, and the apparent size of the dried chains is almost identical to that in solution.展开更多
The sintering process of nanometer size gold clusters is investigated by using molecular dynamics simulation in the frame of embedded atomistic method. Several molecular dynamics simulation techniques are used to obse...The sintering process of nanometer size gold clusters is investigated by using molecular dynamics simulation in the frame of embedded atomistic method. Several molecular dynamics simulation techniques are used to observe and describe the evolution of the sintering process. The energy distribution for single cluster is examined and the snapshots of sintering process of two clusters are recorded. The evolution of sintering is also described by plotting the mass center changes with time for each cluster. The variations of kinetic and potential energy during the process of sintering are monitored and measured to analyze the dominant mechanisms of sintering from the energy point of view.展开更多
Ear size exhibits remarkable diversity in pig breeds. LEM domain-containing 3 （LEMD3） on chromosome 5 is considered as an important candidate for porcine ear size. This is the first study on cloning and characteriza...Ear size exhibits remarkable diversity in pig breeds. LEM domain-containing 3 （LEMD3） on chromosome 5 is considered as an important candidate for porcine ear size. This is the first study on cloning and characterization of LEMD3 cDNA. The complete cDNA contains 4 843 bp, including a 2 736-bp open reading frame （ORF）, a 37-bp 5＂-untranslated region （UTR） and a 2070-bp 3＂-UTR. The complete LEMD3 gene is 126241-bp and contains 13 exons and 12 introns. The ORF encodes a deduced LEMD3 protein of 911 amino acids, which shares 82-94% nucleic acid and 51-96% amino acid identity with other species. A phylogenetic tree constructed based on the amino acid sequences revealed that the porcine LEMD3 protein was closely related with cattle LEMD3. Resequencing of the ORF and promoter of LEMD3 from Minzhu pig and Large White revealed three single nucleotide polymorphisms （SNPs）： L964C〉A in the complete coding region, L4625A〉G in the 3＂ UTR, and L-394T〉C in the promoter region. Genome-wide association study （GWAS） revealed that all of SNPs were shown significant association with ear size in Large WhitexMinzhu pig intercross population. With conditional GWAS, -Iogl0（P-value） decreased by more than 80% when each of three SNPs was included as a fixed effect. These results suggested direct involvement of LEMD3 or close linkage to the causative mutation for ear size. The findings of this study might form the basis for understanding the genetic mechanism of ear size variation in pigs and provide potential molecular markers for screening ear size diversity in pig breeds.展开更多
In this study, finite element analysis （FEA） has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular s...In this study, finite element analysis （FEA） has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular stream peak at different positions along the center axis of the beam, which correspond to local minimums of the molecular densities. With the increase of the throat diameter, the first peak of the Mach number increases first and then decreases, while that of the molecular number density increases gradually. Moreover, both first peaks shift progressively away from the throat. At the last part, we discuss the possible applications of our FEA approach to solve some crucial problems met in modern transportations.展开更多
Aqueous zinc-ion batteries(AZIBs)are one of the most compelling alternatives of lithium-ion batteries due to their inherent safety and economics viability.In response to the growing demand for green and sustainable en...Aqueous zinc-ion batteries(AZIBs)are one of the most compelling alternatives of lithium-ion batteries due to their inherent safety and economics viability.In response to the growing demand for green and sustainable energy storage solutions,organic electrodes with the scalability from inexpensive starting materials and potential for biodegradation after use have become a prominent choice for AZIBs.Despite gratifying progresses of organic molecules with electrochemical performance in AZIBs,the research is still in infancy and hampered by certain issues due to the underlying complex electrochemistry.Strategies for designing organic electrode materials for AZIBs with high specific capacity and long cycling life are discussed in detail in this review.Specifically,we put emphasis on the unique electrochemistry of different redox-active structures to provide in-depth understanding of their working mechanisms.In addition,we highlight the importance of molecular size/dimension regarding their profound impact on electrochemical performances.Finally,challenges and perspectives are discussed from the developing point of view for future AZIBs.We hope to provide a valuable evaluation on organic electrode materials for AZIBs in our context and give inspiration for the rational design of high-performance AZIBs.展开更多
The molecular weight distribution (MWD) of dissolved organic matter (DOM) in lake waters from Lake Hongfeng was examined using high performance size exclusion chromatography (HPSEC) with UV-vis absorbance and fluoresc...The molecular weight distribution (MWD) of dissolved organic matter (DOM) in lake waters from Lake Hongfeng was examined using high performance size exclusion chromatography (HPSEC) with UV-vis absorbance and fluorescence detection. The elution curves obtained by absorbance and fluorescence techniques expressed similar patterns, with the exception of diminishing of large fraction and the peaks behind several seconds in fluorescence chromatograms. According to its molecular weight (MW), DOM in water samples is divided into several fractions: large ({>3.5} kDa); medium-large ({3.5}-{2.0} kDa); medium ({2.0}-{1.0} kDa) and small ({<1.0} kDa). The average molecular weight was calculated using the elution curve detected by UV-vis absorbance and fluorescence detection techniques. The results showed that the weight-average molecular weight (Mw) and number-average molecular weight (Mn) calculated by UV-vis absorbance techniques range from 1750 to 2050 Dalton and from 1450 to 1850 Dalton, respectively. And the Mw and Mn obtained by fluorescence detection are lower by 50 to 400 Dalton. As a reference, the molecular weight of Fluka humic acid (FHA) is larger than that of water samples by about 200 Dalton. The average molecular weight of DOM for water samples collected in March and July was compared. The results revealed that the molecular weight is lower for water samples obtained in July than that obtained in March, indicating the ambient environment has an influence on the molecular weight, including photo-degradation and biological activity.展开更多
This paper presents a theoretical method for predicting the effective diffusion coefficient of macromolecules in the microporous membrfines in view of the effects of molecular dimension and configuration. On the basi...This paper presents a theoretical method for predicting the effective diffusion coefficient of macromolecules in the microporous membrfines in view of the effects of molecular dimension and configuration. On the basis of the hindered diffusion theory of spherical neutral macromolecules in a micropore of a long cylinder, the effects of molecular dimension and configuration are studied by defining two molecular dimensions:the mean projected radius to predict the concentration partition and the ' hydrodynamically equivalent sphere' radius to evaluate the hydrodynamic reverse drag force. The quantitative comparison shows that the effective diffusion coefficients for different macromolecules predicted by the present method are more consistent with the available published experimental data.展开更多
基金supported by the National Basic Research Program of China(2006CB202505).
文摘Two kinds of heavy oils were fractionated into eight fractions by Liquid-Solid Adsorption Chromatography,respectively,and samples were collected to measure properties.According to the elemental analysis,molecular weight and 1H-NMR data,average molecular structures of polycyclic aromatic and heavy resin were constructed with improved Brown-Ladner(B-L)method and several corrections.And then,the most stable conformations of polycyclic aromatic and heavy resin in vacuum and toluene solution were obtained by molecular dynamic simulation,and the molecular size was gotten via the radius of gyration analysis.The results showed that the radius of gyration of polycyclic aromatic and heavy resin was 0.55-0.70 nm in vacuum and 0.60-0.90 nm in toluene solution.With molecular weight increasing,the molecular size in vacuum and toluene solution also increased.Due to the swelling behavior of solvent,the alkyl side chains of heavy oil molecule in solution were more stretched.Thus,the molecular size in toluene solution was larger than that in vacuum.
基金Supported by the National Natural Science Foundation of China（No.21174053）.
文摘The effects of the concentration of sodium chloride in an aqueous solution（cNacl and the temperature on the molecular size of poly（sulfobetaine methacrylate）（PSBMA） were studied via viscometry and dynamic light scattering（DLS）. The morphology of single-chain PSBMA was determined by atomic force microscopy（AFM）. The results demonstrate that the hydrodynamic diameter of PSBMA can be expressed as a continuous function of CNaCl, with the molecular size of PSBMA increasing and eventually approaching an asymptotic value with increasing CNaCl. The molecular size of PSBMA at a lower CNaCI（0.04 mol/L） increases with increasing temperature, which is the opposite of the temperature effect at a higher CNaCl（2.0 mol/L）. Therefore, the internal structure of PSBMA chains in solutions with a low salt concentration differs from that in solutions with a high salt concentration. In addition, the morphology of single chains of PSBMA appears to be spherical, containing 89% void space, and the apparent size of the dried chains is almost identical to that in solution.
文摘The sintering process of nanometer size gold clusters is investigated by using molecular dynamics simulation in the frame of embedded atomistic method. Several molecular dynamics simulation techniques are used to observe and describe the evolution of the sintering process. The energy distribution for single cluster is examined and the snapshots of sintering process of two clusters are recorded. The evolution of sintering is also described by plotting the mass center changes with time for each cluster. The variations of kinetic and potential energy during the process of sintering are monitored and measured to analyze the dominant mechanisms of sintering from the energy point of view.
基金supported by the Agricultural Science and Technology Innovation Program, China (ASTIPIAS02)the National Key Technology R&D Program of China (2011BAD28B01)the Earmarked Fund for Modern Agro-Industry Technology Research System of China, and foundation from Chinese Academy of Agricultural Sciences (2014ZL006)
文摘Ear size exhibits remarkable diversity in pig breeds. LEM domain-containing 3 （LEMD3） on chromosome 5 is considered as an important candidate for porcine ear size. This is the first study on cloning and characterization of LEMD3 cDNA. The complete cDNA contains 4 843 bp, including a 2 736-bp open reading frame （ORF）, a 37-bp 5＂-untranslated region （UTR） and a 2070-bp 3＂-UTR. The complete LEMD3 gene is 126241-bp and contains 13 exons and 12 introns. The ORF encodes a deduced LEMD3 protein of 911 amino acids, which shares 82-94% nucleic acid and 51-96% amino acid identity with other species. A phylogenetic tree constructed based on the amino acid sequences revealed that the porcine LEMD3 protein was closely related with cattle LEMD3. Resequencing of the ORF and promoter of LEMD3 from Minzhu pig and Large White revealed three single nucleotide polymorphisms （SNPs）： L964C〉A in the complete coding region, L4625A〉G in the 3＂ UTR, and L-394T〉C in the promoter region. Genome-wide association study （GWAS） revealed that all of SNPs were shown significant association with ear size in Large WhitexMinzhu pig intercross population. With conditional GWAS, -Iogl0（P-value） decreased by more than 80% when each of three SNPs was included as a fixed effect. These results suggested direct involvement of LEMD3 or close linkage to the causative mutation for ear size. The findings of this study might form the basis for understanding the genetic mechanism of ear size variation in pigs and provide potential molecular markers for screening ear size diversity in pig breeds.
基金financially supported by the Science Foundation for International Cooperation of Sichuan Province (2014HH0016)the Fundamental Research Funds for the Central Universities (SWJTU2014: A0920502051113-10000)National Magnetic Confinement Fusion Science Program (2011GB112001)
文摘In this study, finite element analysis （FEA） has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular stream peak at different positions along the center axis of the beam, which correspond to local minimums of the molecular densities. With the increase of the throat diameter, the first peak of the Mach number increases first and then decreases, while that of the molecular number density increases gradually. Moreover, both first peaks shift progressively away from the throat. At the last part, we discuss the possible applications of our FEA approach to solve some crucial problems met in modern transportations.
基金supported in part by the National Natural Science Foundation of China(Nos.22075027,52003030)Starting Grant from Beijing Institute of Technology and financial support from the State Key Laboratory of Explosion Science and Technology(YBKT21-06,YKBT23-05).
文摘Aqueous zinc-ion batteries(AZIBs)are one of the most compelling alternatives of lithium-ion batteries due to their inherent safety and economics viability.In response to the growing demand for green and sustainable energy storage solutions,organic electrodes with the scalability from inexpensive starting materials and potential for biodegradation after use have become a prominent choice for AZIBs.Despite gratifying progresses of organic molecules with electrochemical performance in AZIBs,the research is still in infancy and hampered by certain issues due to the underlying complex electrochemistry.Strategies for designing organic electrode materials for AZIBs with high specific capacity and long cycling life are discussed in detail in this review.Specifically,we put emphasis on the unique electrochemistry of different redox-active structures to provide in-depth understanding of their working mechanisms.In addition,we highlight the importance of molecular size/dimension regarding their profound impact on electrochemical performances.Finally,challenges and perspectives are discussed from the developing point of view for future AZIBs.We hope to provide a valuable evaluation on organic electrode materials for AZIBs in our context and give inspiration for the rational design of high-performance AZIBs.
文摘The molecular weight distribution (MWD) of dissolved organic matter (DOM) in lake waters from Lake Hongfeng was examined using high performance size exclusion chromatography (HPSEC) with UV-vis absorbance and fluorescence detection. The elution curves obtained by absorbance and fluorescence techniques expressed similar patterns, with the exception of diminishing of large fraction and the peaks behind several seconds in fluorescence chromatograms. According to its molecular weight (MW), DOM in water samples is divided into several fractions: large ({>3.5} kDa); medium-large ({3.5}-{2.0} kDa); medium ({2.0}-{1.0} kDa) and small ({<1.0} kDa). The average molecular weight was calculated using the elution curve detected by UV-vis absorbance and fluorescence detection techniques. The results showed that the weight-average molecular weight (Mw) and number-average molecular weight (Mn) calculated by UV-vis absorbance techniques range from 1750 to 2050 Dalton and from 1450 to 1850 Dalton, respectively. And the Mw and Mn obtained by fluorescence detection are lower by 50 to 400 Dalton. As a reference, the molecular weight of Fluka humic acid (FHA) is larger than that of water samples by about 200 Dalton. The average molecular weight of DOM for water samples collected in March and July was compared. The results revealed that the molecular weight is lower for water samples obtained in July than that obtained in March, indicating the ambient environment has an influence on the molecular weight, including photo-degradation and biological activity.
文摘This paper presents a theoretical method for predicting the effective diffusion coefficient of macromolecules in the microporous membrfines in view of the effects of molecular dimension and configuration. On the basis of the hindered diffusion theory of spherical neutral macromolecules in a micropore of a long cylinder, the effects of molecular dimension and configuration are studied by defining two molecular dimensions:the mean projected radius to predict the concentration partition and the ' hydrodynamically equivalent sphere' radius to evaluate the hydrodynamic reverse drag force. The quantitative comparison shows that the effective diffusion coefficients for different macromolecules predicted by the present method are more consistent with the available published experimental data.
