Highly efficient synthesis methods have been developed and characteristics of nanometallocarbosilanes molecular structure were studied by the research team of GNIIChTEOS （State Research Institute for Chemistry and Te...Highly efficient synthesis methods have been developed and characteristics of nanometallocarbosilanes molecular structure were studied by the research team of GNIIChTEOS （State Research Institute for Chemistry and Technology of Organoelement Compounds）. Nanometallocarbosilanes were synthesized by thermal co-condensation of oligocarbosilanes and alkyl amides of refractory metals. Initial, intermediate and final products of side reactions were characterized by 1H, 13C, 29Si NMR （nuclear magnetic resonance）, IR （infra-red） spectroscopy, GPC （gel-penetrating chromatography）, TGA （thermal gravimetric analysis）, TEM （transmission electron microscopy）, SEM （scanning electron microscopy）, RES （X-ray phase analysis） and elemental analysis. The proposed synthesis method of nanometallocarbosilanes was lbund to produce fusable soluble organosilicon oligomers with homogeneous distribution of nanoscale （10-20 nm） metal particles in the oligomer matrix. A computational model of the group and elemental composition of nanometallocarbosilanes was developed; it was shown that they are molecular globules of near-spherical shape and rigid polycyclic structure. Thermochemical treatment of nanometallocarbosilanes leads to SiC-nanoceramics （a high yield of up to 75-80 mass%） modified by metal nanoparticles （20-30 nm） contributing to its stabilization. The application of preceramic oxygen-free nanometallocarbosilanes will make it possible to advance in solving the problem of ceramic composite materials with long-term resistance at temperatures above 1,500 ℃ in oxidizing environments.展开更多
Ballistic thermal transport properties in a cylindrical quantum structure modulated with double quantum dots(DQDs) are investigated.Results show that the transmission coefficients exhibit the irregular oscillation.Som...Ballistic thermal transport properties in a cylindrical quantum structure modulated with double quantum dots(DQDs) are investigated.Results show that the transmission coefficients exhibit the irregular oscillation.Some resonant transmission peaks and stop-frequency gaps can be observed,and the number and positions of these peaks and gaps are sensitive to the sizes of DQDs.With increasing the temperature,the thermal conductance undergoes a transition from the decrease to increase,and can be efficiently tuned by modulating the radius,length of DQDs as well as the interval between DQDs.In addition,at low temperatures,the enhancement of the thermal conductance can be also observed in this case.Some similarities and differences between the cylindrical and rectangular structures are identified.展开更多
The popular and effective food preservation technology based on refrigeration is not sufficient for high-quality products while undergoing logistic operations(transport and retail). One of the basic factors that affec...The popular and effective food preservation technology based on refrigeration is not sufficient for high-quality products while undergoing logistic operations(transport and retail). One of the basic factors that affects the quality of chilled and frozen food products during storage and transport is packaging. A protective function of packaging strongly depends on the material used and its composition. There are different kinds of thermal insulation used for food packaging. One of them, proposed by the authors is a multilayer structure of insulation made of rectangular air cells. The insulation can be prepared by means of plastic film featuring various properties. The paper presents how to improve an effective material designed for food freezing and transport aiming to enhance its thermal resistance through the application of different transparency, reflectivity and emissivity of the film. Mathematical model based on heat exchange equations, including conduction, convection and radiation throughout a number of parallel internal sheets of film of multilayer structures was proposed. Thermal properties depending on different transparency, reflectivity and emissivity of the film were analyzed. The model was verified experimentally showing its compatibility and obtaining a significant influence of thermal resistance according to the type of film used to make air structures, the number and thickness of its layers as well as the gaps between internal folds. For multi-layer insulation designed for the insulation of packed frozen food in the shape of a rectangle, it was recommended to apply film transmittance as small as possible for the internal parts of the structure.展开更多
The effect of grid shape on the properties of transparent conductive films(TCFs) is theoretically analyzed and experimentally verified. The light transmittance by three types of grid shapes: triangle, square and hexag...The effect of grid shape on the properties of transparent conductive films(TCFs) is theoretically analyzed and experimentally verified. The light transmittance by three types of grid shapes: triangle, square and hexagon have been theoretically calculated and simulated. It was found that hexagonal grid unit has the highest light transmittance limit under the practical lattice parameters and its decrease in light transmittance caused by the increase of line width in printing process is the least. The grid of three different shapes with same theoretical transmittance is fabricated through flexographic printing. The result shows that the actual light transmittance of the printed TCFs is lower than its theoretical value because of the inevitable width increase of printed grid lines, with slight difference between the three shapes. However, it is greatly different in terms of conductivity, leading to variation in the quality factor Q(defined as the ratio of light transmittance to total resistance) which represents the performance of TCFs. The Q of hexagonal grid(6.04) is the highest, which is 21% higher than that of the square grid.展开更多
Considering repulsive interspecies interactions,we study the dynamical properties of bright-bright solitons in two species Bose-Einstein condensates by using a variational approach combined with numerical simulation.I...Considering repulsive interspecies interactions,we study the dynamical properties of bright-bright solitons in two species Bose-Einstein condensates by using a variational approach combined with numerical simulation.It is shown that the interactions between bright-bright solitons vary from repulsive to attractive interactions with the increasing their separating distances,and at equilibrium position the bright-bright solitons are localized.Interestingly,a transition from reflection-to transmission-collision is firstly observed,different from previous results of only reflection collision appearing there.These results will be helpful for the experimental manipulating such solitons.展开更多
文摘Highly efficient synthesis methods have been developed and characteristics of nanometallocarbosilanes molecular structure were studied by the research team of GNIIChTEOS （State Research Institute for Chemistry and Technology of Organoelement Compounds）. Nanometallocarbosilanes were synthesized by thermal co-condensation of oligocarbosilanes and alkyl amides of refractory metals. Initial, intermediate and final products of side reactions were characterized by 1H, 13C, 29Si NMR （nuclear magnetic resonance）, IR （infra-red） spectroscopy, GPC （gel-penetrating chromatography）, TGA （thermal gravimetric analysis）, TEM （transmission electron microscopy）, SEM （scanning electron microscopy）, RES （X-ray phase analysis） and elemental analysis. The proposed synthesis method of nanometallocarbosilanes was lbund to produce fusable soluble organosilicon oligomers with homogeneous distribution of nanoscale （10-20 nm） metal particles in the oligomer matrix. A computational model of the group and elemental composition of nanometallocarbosilanes was developed; it was shown that they are molecular globules of near-spherical shape and rigid polycyclic structure. Thermochemical treatment of nanometallocarbosilanes leads to SiC-nanoceramics （a high yield of up to 75-80 mass%） modified by metal nanoparticles （20-30 nm） contributing to its stabilization. The application of preceramic oxygen-free nanometallocarbosilanes will make it possible to advance in solving the problem of ceramic composite materials with long-term resistance at temperatures above 1,500 ℃ in oxidizing environments.
基金supported by the National Natural Science Foundation of China (Grant No.11204074)
文摘Ballistic thermal transport properties in a cylindrical quantum structure modulated with double quantum dots(DQDs) are investigated.Results show that the transmission coefficients exhibit the irregular oscillation.Some resonant transmission peaks and stop-frequency gaps can be observed,and the number and positions of these peaks and gaps are sensitive to the sizes of DQDs.With increasing the temperature,the thermal conductance undergoes a transition from the decrease to increase,and can be efficiently tuned by modulating the radius,length of DQDs as well as the interval between DQDs.In addition,at low temperatures,the enhancement of the thermal conductance can be also observed in this case.Some similarities and differences between the cylindrical and rectangular structures are identified.
基金financially supported by Project No 0401/0180/17 of Wroclaw University of Science and Technology
文摘The popular and effective food preservation technology based on refrigeration is not sufficient for high-quality products while undergoing logistic operations(transport and retail). One of the basic factors that affects the quality of chilled and frozen food products during storage and transport is packaging. A protective function of packaging strongly depends on the material used and its composition. There are different kinds of thermal insulation used for food packaging. One of them, proposed by the authors is a multilayer structure of insulation made of rectangular air cells. The insulation can be prepared by means of plastic film featuring various properties. The paper presents how to improve an effective material designed for food freezing and transport aiming to enhance its thermal resistance through the application of different transparency, reflectivity and emissivity of the film. Mathematical model based on heat exchange equations, including conduction, convection and radiation throughout a number of parallel internal sheets of film of multilayer structures was proposed. Thermal properties depending on different transparency, reflectivity and emissivity of the film were analyzed. The model was verified experimentally showing its compatibility and obtaining a significant influence of thermal resistance according to the type of film used to make air structures, the number and thickness of its layers as well as the gaps between internal folds. For multi-layer insulation designed for the insulation of packed frozen food in the shape of a rectangle, it was recommended to apply film transmittance as small as possible for the internal parts of the structure.
基金supported by the Beijing Municipal Commission of Education Foundation for School Innovation Ability Promotion Plan(Grant No.TJSHG201310015016)the Key Project of Beijing Institute of Graphic Communication(Grant No.Ea201501)the Creative Groups of Materials and Technology of Printed Electronics(Grant No.23190113100)
文摘The effect of grid shape on the properties of transparent conductive films(TCFs) is theoretically analyzed and experimentally verified. The light transmittance by three types of grid shapes: triangle, square and hexagon have been theoretically calculated and simulated. It was found that hexagonal grid unit has the highest light transmittance limit under the practical lattice parameters and its decrease in light transmittance caused by the increase of line width in printing process is the least. The grid of three different shapes with same theoretical transmittance is fabricated through flexographic printing. The result shows that the actual light transmittance of the printed TCFs is lower than its theoretical value because of the inevitable width increase of printed grid lines, with slight difference between the three shapes. However, it is greatly different in terms of conductivity, leading to variation in the quality factor Q(defined as the ratio of light transmittance to total resistance) which represents the performance of TCFs. The Q of hexagonal grid(6.04) is the highest, which is 21% higher than that of the square grid.
基金Supported by National Natural Science Foundation of China under Grant Nos.51032002 and 11074212Foundation for the Author of National Excellent Doctoral Dissertation of China under Grant No.200726+1 种基金the Key Project of the National HighTechnology Research and Development Program ("863" Program) of China under Grant No.2011AA050526Hunan Provincial Innovation Foundation for Postgraduate under Grant No.CX2010B254
文摘Considering repulsive interspecies interactions,we study the dynamical properties of bright-bright solitons in two species Bose-Einstein condensates by using a variational approach combined with numerical simulation.It is shown that the interactions between bright-bright solitons vary from repulsive to attractive interactions with the increasing their separating distances,and at equilibrium position the bright-bright solitons are localized.Interestingly,a transition from reflection-to transmission-collision is firstly observed,different from previous results of only reflection collision appearing there.These results will be helpful for the experimental manipulating such solitons.
