The structural and the size evolution of embedded In nanoparticles in Al synthesized by ion implantation and subsequent annealing are experimentally investigated. The average radius r of In nanoparticles is determined...The structural and the size evolution of embedded In nanoparticles in Al synthesized by ion implantation and subsequent annealing are experimentally investigated. The average radius r of In nanoparticles is determined as a function of annealing time in a temperature range between 423 K and 453 K. The structural transition of In nanoparticles with the crystallographic orientation In （200）[002]｜｜Al （200）[002] is observed to change into In （111）[110]｜｜Al （002）[110] with a critical particle radius between 2.3 nm and 2.6 nm. In addition, the growth of In nanoparticles in the annealing process is evidently governed by the diffusion limited Ostwald ripening. By further analyzing the experimental data, values of diffusion coefficient and activation energy are obtained.展开更多
The dynamic activity of transposable elements(TEs)contributes to the vast diversity of genome size and architecture among plants.Here,we examined the genomic distribution and transposition activity of long terminal re...The dynamic activity of transposable elements(TEs)contributes to the vast diversity of genome size and architecture among plants.Here,we examined the genomic distribution and transposition activity of long terminal repeat retrotransposons(LTR-RTs)in Arabidopsis thaliana(Ath)and three of its relatives,Arabidopsis lyrata(Aly),Eutrema salsugineum(Esa),and Schrenkiella parvula(Spa),in Brassicaceae.Our analyses revealed the distinct evolutionary dynamics of Gypsy retrotransposons,which reflects the different patterns of genome size changes of the four species over the past million years.The rate of Gypsy transposition in Aly is approximately five times more rapid than that of Ath and Esa,suggesting an expanding Aly genome.Gypsy insertions in Esa are strictly confined to pericentromeric heterochromatin and associated with dramatic centromere expansion.In contrast,Gypsy insertions in Spa have been largely suppressed over the last million years,likely as a result of a combination of an inherent molecular mechanism of preferential DNA removal and purifying selection at Gypsy elements.Additionally,species-specific clades of Gypsy elements shaped the distinct genome architectures of Aly and Esa.展开更多
Two types of polymeric surfactants, PEG300 and PVP40000, were used for the preparation of magnetic ferrite MFe2O4 （M- Mn, Fe） colloidal nanocrystals using a solvothermal reaction method. The effect of spinel type ef...Two types of polymeric surfactants, PEG300 and PVP40000, were used for the preparation of magnetic ferrite MFe2O4 （M- Mn, Fe） colloidal nanocrystals using a solvothermal reaction method. The effect of spinel type effect on the size evolution of various nanoparticles was investigated. It was found that Fe3O4 nanoparticles exhibited higher crystalinity and size evolution than MnFe2O4 nanoparticles with use of the two surfactants. It is proposed that this observation is due to fewer tendencies of surfactants on the surface of Fe3O4 building blocks nanoparticles than MnFe2O4. Less amounts of surfactant or capping agent on the surface of nanoparticles lead to the higher crystalibity and larger size. It is also suggested that the type of spinel （normal or inverted spinel） plays a key role on the affinity of the polymeric surfactant on the surface of building blocks.展开更多
Through molecular dynamics（MD） simulation, the dependencies of temperature, grain size and strain rate on the mechanical properties were studied. The simulation results demonstrated that the strain rate from 0.05 to...Through molecular dynamics（MD） simulation, the dependencies of temperature, grain size and strain rate on the mechanical properties were studied. The simulation results demonstrated that the strain rate from 0.05 to 2 ns–1 affected the Young＇s modulus of nickel nanowires slightly, whereas the yield stress increased. The Young＇s modulus decreased approximately linearly; however, the yield stress firstly increased and subsequently dropped as the temperature increased. The Young＇s modulus and yield stress increased as the mean grain size increased from 2.66 to 6.72 nm. Moreover, certain efforts have been made in the microstructure evolution with mechanical properties association under uniaxial tension. Certain phenomena such as the formation of twin structures, which were found in nanowires with larger grain size at higher strain rate and lower temperature, as well as the movement of grain boundaries and dislocation, were detected and discussed in detail. The results demonstrated that the plastic deformation was mainly accommodated by the motion of grain boundaries for smaller grain size. However, for larger grain size, the formations of stacking faults and twins were the main mechanisms of plastic deformation in the polycrystalline nickel nanowire.展开更多
Cationic latexes were prepared through emulsion copolymerization of styrene （St） and butyl acrylate （BA） with a cationic surfactant, cetyl trimethyl ammonium bromide （CTAB）. Latex properties, including particle ...Cationic latexes were prepared through emulsion copolymerization of styrene （St） and butyl acrylate （BA） with a cationic surfactant, cetyl trimethyl ammonium bromide （CTAB）. Latex properties, including particle size, size distribution, （ potential, surface tension and monomer conversion, were determined for latexes prepared with different CTAB amounts. Evolution of these properties during emulsion polymerization was followed in order to understand the mechanism of the particles formation. Results showed that both particle size and 6＂ potential were function of polymerization time and latex solids. Parallel emulsion polymerizations with cationic, anionic charged initiator and charge-free initiators were also carried out, the latex properties were determined at different polymerization time. All these results were attentively interpreted based on the mechanisms of emulsion polymerization, surfactant adsorption and latex particle stabilization.展开更多
In the shaping process of cross wedge rolling（CWR）, metal undergoes a complex microstructural evolution, which affects the quality and mechanical properties of the product. Through secondary development of the DEFOR...In the shaping process of cross wedge rolling（CWR）, metal undergoes a complex microstructural evolution, which affects the quality and mechanical properties of the product. Through secondary development of the DEFORM-3D software, we developed a rigid plastic finite element model for a CWR-processed rear axle tube, coupled with thermomechanical and microstructural aspects of workpieces. Using the developed model, we investigated the microstructural evolution of the CWR process. Also, the influence of numerous parameters, including the initial temperature of workpieces, the roll speed, the forming angle, and the spreading angle, on the grain size and the grain-size uniformity of the rolled workpieces was analyzed. The numerical simulation was verified through rolling and metallographic experiments. Good agreement was obtained between the calculated and experimental results, which demonstrated the reliability of the model constructed in this work.展开更多
Two-phase flow with complex phase interfaces is commonly observed in both nature and industrial processes.The bubble size distribution(BSD) is a crucial parameter in gas-liquid two-phase flow,impacting various flow ch...Two-phase flow with complex phase interfaces is commonly observed in both nature and industrial processes.The bubble size distribution(BSD) is a crucial parameter in gas-liquid two-phase flow,impacting various flow characteristics including interfacial forces,void fraction distribution,and interfacial area transport.Throughout the flow progression,the BSD changes along the channel due to variations in pressure and interactions among bubbles.Accurately predicting the evolution of BSD can enhance the modeling of two-phase flow.This study presents a novel BSD evolution(BSDE) model,where the governing equation for the probability density function is formulated by considering the conservation of bubbles within a onedimensional control volume in the channel.The downstream BSD is predicted based on the upstream BSD and the effects of pressure variations and bubble interactions along the channel.To account for the multiscale nature of the two-phase flow,the bubbles are categorized into small groups(G_(1)) and large groups(G_(2)).Six distinct source term distributions for intra/inter bubble interactions have been developed.Each source term accounts for the distributions of consumed and generated bubbles,ensuring the conservation of bubble volume through constraints on model coefficients.The model has been tested on a tight-lattice rod bundle using experimental data,with deviations of less than 5% and 15% for G_(1)and G_(2) flow,respectively.Since the model development is independent of specific geometry,the framework of the BSDE model can also be effectively applied to channels of varying shapes.展开更多
Transposable elements(TEs)are a major determinant of eukaryotic genome size.The collective properties of a genomic TE community reveal the history of TE/host evolutionary dynamics and impact present-day host structure...Transposable elements(TEs)are a major determinant of eukaryotic genome size.The collective properties of a genomic TE community reveal the history of TE/host evolutionary dynamics and impact present-day host structure and function,from genome to organism levels.In rare cases,TE community/genome size has greatly expanded in animals,associated with increased cell size and changes to anatomy and physiology.Here,we characterize the TE landscape of the genome and transcriptome in an amphibian with a giant genome—the caecilian Ichthyophis bannanicus,which we show has a genome size of 12.2 Gb.Amphibians are an important model system because the clade includes independent cases of genomic gigantism.The I.bannanicus genome differs compositionally from other giant amphibian genomes,but shares a low rate of ectopic recombination-mediated deletion.We examine TE activity using expression and divergence plots;TEs account for 15%of somatic transcription,and most superfamilies appear active.We quantify TE diversity in the caecilian,as well as other vertebrates with a range of genome sizes,using diversity indices commonly applied in community ecology.We synthesize previous models that integrate TE abundance,diversity,and activity,and test whether the caecilian meets model predictions for genomes with high TE abundance.We propose thorough,consistent characterization of TEs to strengthen future comparative analyses.Such analyses will ultimately be required to reveal whether the divergent TE assemblages found across convergent gigantic genomes reflect fundamental shared features of TE/host genome evolutionary dynamics.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11505160)the Director Foundation of Institute of Materials,Chinese Academy of Engineering Physics(Grant No.SJZD201406)
文摘The structural and the size evolution of embedded In nanoparticles in Al synthesized by ion implantation and subsequent annealing are experimentally investigated. The average radius r of In nanoparticles is determined as a function of annealing time in a temperature range between 423 K and 453 K. The structural transition of In nanoparticles with the crystallographic orientation In （200）[002]｜｜Al （200）[002] is observed to change into In （111）[110]｜｜Al （002）[110] with a critical particle radius between 2.3 nm and 2.6 nm. In addition, the growth of In nanoparticles in the annealing process is evidently governed by the diffusion limited Ostwald ripening. By further analyzing the experimental data, values of diffusion coefficient and activation energy are obtained.
基金the“Innovation Project for the Postdoctoral Researchers”in Chinathe“Open Research Fund Program”of Beijing Key Lab of Plant Resource Research and Development,Beijing Technology and Business University。
文摘The dynamic activity of transposable elements(TEs)contributes to the vast diversity of genome size and architecture among plants.Here,we examined the genomic distribution and transposition activity of long terminal repeat retrotransposons(LTR-RTs)in Arabidopsis thaliana(Ath)and three of its relatives,Arabidopsis lyrata(Aly),Eutrema salsugineum(Esa),and Schrenkiella parvula(Spa),in Brassicaceae.Our analyses revealed the distinct evolutionary dynamics of Gypsy retrotransposons,which reflects the different patterns of genome size changes of the four species over the past million years.The rate of Gypsy transposition in Aly is approximately five times more rapid than that of Ath and Esa,suggesting an expanding Aly genome.Gypsy insertions in Esa are strictly confined to pericentromeric heterochromatin and associated with dramatic centromere expansion.In contrast,Gypsy insertions in Spa have been largely suppressed over the last million years,likely as a result of a combination of an inherent molecular mechanism of preferential DNA removal and purifying selection at Gypsy elements.Additionally,species-specific clades of Gypsy elements shaped the distinct genome architectures of Aly and Esa.
文摘Two types of polymeric surfactants, PEG300 and PVP40000, were used for the preparation of magnetic ferrite MFe2O4 （M- Mn, Fe） colloidal nanocrystals using a solvothermal reaction method. The effect of spinel type effect on the size evolution of various nanoparticles was investigated. It was found that Fe3O4 nanoparticles exhibited higher crystalinity and size evolution than MnFe2O4 nanoparticles with use of the two surfactants. It is proposed that this observation is due to fewer tendencies of surfactants on the surface of Fe3O4 building blocks nanoparticles than MnFe2O4. Less amounts of surfactant or capping agent on the surface of nanoparticles lead to the higher crystalibity and larger size. It is also suggested that the type of spinel （normal or inverted spinel） plays a key role on the affinity of the polymeric surfactant on the surface of building blocks.
基金Supported by the National Natural Science Foundation of China(11102139,11472195)the Natural Science Foundation of Hubei Province of China(2014CFB713)
文摘Through molecular dynamics（MD） simulation, the dependencies of temperature, grain size and strain rate on the mechanical properties were studied. The simulation results demonstrated that the strain rate from 0.05 to 2 ns–1 affected the Young＇s modulus of nickel nanowires slightly, whereas the yield stress increased. The Young＇s modulus decreased approximately linearly; however, the yield stress firstly increased and subsequently dropped as the temperature increased. The Young＇s modulus and yield stress increased as the mean grain size increased from 2.66 to 6.72 nm. Moreover, certain efforts have been made in the microstructure evolution with mechanical properties association under uniaxial tension. Certain phenomena such as the formation of twin structures, which were found in nanowires with larger grain size at higher strain rate and lower temperature, as well as the movement of grain boundaries and dislocation, were detected and discussed in detail. The results demonstrated that the plastic deformation was mainly accommodated by the motion of grain boundaries for smaller grain size. However, for larger grain size, the formations of stacking faults and twins were the main mechanisms of plastic deformation in the polycrystalline nickel nanowire.
基金supported by the Natural Science Foundation of Shandong Province,China(No.Z2008B07)the National Natural Science Foundation of China(No.20874040)
文摘Cationic latexes were prepared through emulsion copolymerization of styrene （St） and butyl acrylate （BA） with a cationic surfactant, cetyl trimethyl ammonium bromide （CTAB）. Latex properties, including particle size, size distribution, （ potential, surface tension and monomer conversion, were determined for latexes prepared with different CTAB amounts. Evolution of these properties during emulsion polymerization was followed in order to understand the mechanism of the particles formation. Results showed that both particle size and 6＂ potential were function of polymerization time and latex solids. Parallel emulsion polymerizations with cationic, anionic charged initiator and charge-free initiators were also carried out, the latex properties were determined at different polymerization time. All these results were attentively interpreted based on the mechanisms of emulsion polymerization, surfactant adsorption and latex particle stabilization.
基金support given by the National Natural Science Foundation of China (No.51505026)
文摘In the shaping process of cross wedge rolling（CWR）, metal undergoes a complex microstructural evolution, which affects the quality and mechanical properties of the product. Through secondary development of the DEFORM-3D software, we developed a rigid plastic finite element model for a CWR-processed rear axle tube, coupled with thermomechanical and microstructural aspects of workpieces. Using the developed model, we investigated the microstructural evolution of the CWR process. Also, the influence of numerous parameters, including the initial temperature of workpieces, the roll speed, the forming angle, and the spreading angle, on the grain size and the grain-size uniformity of the rolled workpieces was analyzed. The numerical simulation was verified through rolling and metallographic experiments. Good agreement was obtained between the calculated and experimental results, which demonstrated the reliability of the model constructed in this work.
基金supported by the National Natural Science Foundation of China (12322510 and 12275174)the Shanghai Rising-Star Program (22QA1404500)+1 种基金the Science and Technology Commission of Shanghai Municipality (24DZ3100300)the Lingchuang Project of China National Nuclear Corporation
文摘Two-phase flow with complex phase interfaces is commonly observed in both nature and industrial processes.The bubble size distribution(BSD) is a crucial parameter in gas-liquid two-phase flow,impacting various flow characteristics including interfacial forces,void fraction distribution,and interfacial area transport.Throughout the flow progression,the BSD changes along the channel due to variations in pressure and interactions among bubbles.Accurately predicting the evolution of BSD can enhance the modeling of two-phase flow.This study presents a novel BSD evolution(BSDE) model,where the governing equation for the probability density function is formulated by considering the conservation of bubbles within a onedimensional control volume in the channel.The downstream BSD is predicted based on the upstream BSD and the effects of pressure variations and bubble interactions along the channel.To account for the multiscale nature of the two-phase flow,the bubbles are categorized into small groups(G_(1)) and large groups(G_(2)).Six distinct source term distributions for intra/inter bubble interactions have been developed.Each source term accounts for the distributions of consumed and generated bubbles,ensuring the conservation of bubble volume through constraints on model coefficients.The model has been tested on a tight-lattice rod bundle using experimental data,with deviations of less than 5% and 15% for G_(1)and G_(2) flow,respectively.Since the model development is independent of specific geometry,the framework of the BSDE model can also be effectively applied to channels of varying shapes.
基金supported by the National Natural Science Foundation of China(Grant No.31570391 to WJ)the National Key R&D Program of China(Grant No.2016YFC0503200)the National Science Foundation of USA(Grant No.1911585 to RLM)
文摘Transposable elements(TEs)are a major determinant of eukaryotic genome size.The collective properties of a genomic TE community reveal the history of TE/host evolutionary dynamics and impact present-day host structure and function,from genome to organism levels.In rare cases,TE community/genome size has greatly expanded in animals,associated with increased cell size and changes to anatomy and physiology.Here,we characterize the TE landscape of the genome and transcriptome in an amphibian with a giant genome—the caecilian Ichthyophis bannanicus,which we show has a genome size of 12.2 Gb.Amphibians are an important model system because the clade includes independent cases of genomic gigantism.The I.bannanicus genome differs compositionally from other giant amphibian genomes,but shares a low rate of ectopic recombination-mediated deletion.We examine TE activity using expression and divergence plots;TEs account for 15%of somatic transcription,and most superfamilies appear active.We quantify TE diversity in the caecilian,as well as other vertebrates with a range of genome sizes,using diversity indices commonly applied in community ecology.We synthesize previous models that integrate TE abundance,diversity,and activity,and test whether the caecilian meets model predictions for genomes with high TE abundance.We propose thorough,consistent characterization of TEs to strengthen future comparative analyses.Such analyses will ultimately be required to reveal whether the divergent TE assemblages found across convergent gigantic genomes reflect fundamental shared features of TE/host genome evolutionary dynamics.
