Based on the concepts of fractal super fibers, the （3, 9＋2）-circle and （9＋2, 3）-circle binary fractal sets are abstracted form such prototypes as wool fibers and human hairs, with the （3）-circle and the （9＋2...Based on the concepts of fractal super fibers, the （3, 9＋2）-circle and （9＋2, 3）-circle binary fractal sets are abstracted form such prototypes as wool fibers and human hairs, with the （3）-circle and the （9＋2）-circle fractal sets as subsets. As far as the （9＋2） topological patterns are concerned, the following propositions are proved： The （9＋2） topological patterns accurately exist, but are not unique. Their total number is 9. Among them, only two are allotropes. In other words, among the nine topological patterns, only two are independent （or fundamental）. Besides, we demonstrate that the （3, 9＋2）-circle and （9＋2, 3）-circle fractal sets are golden ones with symmetry breaking.展开更多
In our previous work,anisotropic chemical bonding,low shear deformation resistance,damage tolerance ability,low thermal conductivity,and moderate thermal expansion coefficient of Y_(4)Al_(2)O_(9)(YAM)were predicted.In...In our previous work,anisotropic chemical bonding,low shear deformation resistance,damage tolerance ability,low thermal conductivity,and moderate thermal expansion coefficient of Y_(4)Al_(2)O_(9)(YAM)were predicted.In this work,phase-pure YAM powders were synthesized by solid-state reaction between Y2O3 and Al_(2)O_(3)and bulk YAM ceramics were prepared by hot-pressing method.Lattice parameters and a new set of X-ray powder diffraction data were obtained by Rietveld refinement.The mechanical and thermal properties of dense YAM ceramics were investigated.The measured elastic moduli are close to the theoretical predicted values and the stiffness can be maintained up to 1400℃.The flexural strength and fracture toughness are 252.1±7.3 MPa and 3.36±0.20 MPa·m^(1/2),respectively.Damage tolerance of YAM was also experimentally proved.The measured average linear thermal expansion coefficient(TEC)of YAM is 7.37×10^(-6)K^(-1),which is very close to the theoretical predicted value.Using high-temperature X-ray diffraction(XRD)analysis,volumetric TEC is determined(23.37±1.61)×10^(-6)K^(-1)and the anisotropic TEC areaa=7.34×10^(-6)K^(-1),ab=7.54×10^(-6)K^(-1),andac=7.61×10^(-6)K^(-1).展开更多
Influenza A virus has caused huge damage to human health and poultry production worldwide,but its global transmission patterns and influencing factors remain unclear.Here,by using the Nearest Genetic Distance Approach...Influenza A virus has caused huge damage to human health and poultry production worldwide,but its global transmission patterns and influencing factors remain unclear.Here,by using the Nearest Genetic Distance Approach with genetic sequences data,we reconstructed the global transmission patterns of 4 most common subtypes of influenza A virus(H1N1,H3N2,H5N1,and H7N9)and analyzed associations of transmission velocity of these influenza viruses with environmental factors.We found that the transmission patterns of influenza viruses and their associations with environmental factors were closely related to their host properties.H1N1 and H3N2,which are mainly held by humans,are transmitted between regions at high velocity and over long distances,which may be due to human transportation via airplane;while H5N1 and H7N9,which are mainly carried by animals,are transmitted locally at short distances and at low velocity,which may be facilitated by poultry transportation via railways or high ways.H1N1 and H3N2 spread faster in cold seasons,while H5N1 spread faster in both cold and warm seasons,and H7N9 spread faster in wet seasons.H1N1,H3N2,and H5N1 spread faster in places with both high and low human densities.Our study provided novel insights into the global transmission patterns,processes,and management strategies for influenza under accelerated global change.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 10572076 and10872114)the Natural Science Foundation of Jiangsu Province (No. BK2008370)
文摘Based on the concepts of fractal super fibers, the （3, 9＋2）-circle and （9＋2, 3）-circle binary fractal sets are abstracted form such prototypes as wool fibers and human hairs, with the （3）-circle and the （9＋2）-circle fractal sets as subsets. As far as the （9＋2） topological patterns are concerned, the following propositions are proved： The （9＋2） topological patterns accurately exist, but are not unique. Their total number is 9. Among them, only two are allotropes. In other words, among the nine topological patterns, only two are independent （or fundamental）. Besides, we demonstrate that the （3, 9＋2）-circle and （9＋2, 3）-circle fractal sets are golden ones with symmetry breaking.
基金supported by the National Outstanding Young Scientist Foundation for Y.C.Zhou under Grant No.59925208the National Natural Science Foundation of China under Grant Nos.50832008 and U1435206.
文摘In our previous work,anisotropic chemical bonding,low shear deformation resistance,damage tolerance ability,low thermal conductivity,and moderate thermal expansion coefficient of Y_(4)Al_(2)O_(9)(YAM)were predicted.In this work,phase-pure YAM powders were synthesized by solid-state reaction between Y2O3 and Al_(2)O_(3)and bulk YAM ceramics were prepared by hot-pressing method.Lattice parameters and a new set of X-ray powder diffraction data were obtained by Rietveld refinement.The mechanical and thermal properties of dense YAM ceramics were investigated.The measured elastic moduli are close to the theoretical predicted values and the stiffness can be maintained up to 1400℃.The flexural strength and fracture toughness are 252.1±7.3 MPa and 3.36±0.20 MPa·m^(1/2),respectively.Damage tolerance of YAM was also experimentally proved.The measured average linear thermal expansion coefficient(TEC)of YAM is 7.37×10^(-6)K^(-1),which is very close to the theoretical predicted value.Using high-temperature X-ray diffraction(XRD)analysis,volumetric TEC is determined(23.37±1.61)×10^(-6)K^(-1)and the anisotropic TEC areaa=7.34×10^(-6)K^(-1),ab=7.54×10^(-6)K^(-1),andac=7.61×10^(-6)K^(-1).
基金This work was supported by grants from the National Natural Science Foundation of China(Grant Nos.3191101787,31970153,31630079)the National Key R&D Program of China(2016YFD0500206)+1 种基金the IUBS/ISZS program of“Biological Consequences of Global Change”,and Strategic Priority Research Program of the Chinese Academy of Sciences(XDB29010000)J.L.is supported by Youth Innovation Promotion Association of CAS(2019091).
文摘Influenza A virus has caused huge damage to human health and poultry production worldwide,but its global transmission patterns and influencing factors remain unclear.Here,by using the Nearest Genetic Distance Approach with genetic sequences data,we reconstructed the global transmission patterns of 4 most common subtypes of influenza A virus(H1N1,H3N2,H5N1,and H7N9)and analyzed associations of transmission velocity of these influenza viruses with environmental factors.We found that the transmission patterns of influenza viruses and their associations with environmental factors were closely related to their host properties.H1N1 and H3N2,which are mainly held by humans,are transmitted between regions at high velocity and over long distances,which may be due to human transportation via airplane;while H5N1 and H7N9,which are mainly carried by animals,are transmitted locally at short distances and at low velocity,which may be facilitated by poultry transportation via railways or high ways.H1N1 and H3N2 spread faster in cold seasons,while H5N1 spread faster in both cold and warm seasons,and H7N9 spread faster in wet seasons.H1N1,H3N2,and H5N1 spread faster in places with both high and low human densities.Our study provided novel insights into the global transmission patterns,processes,and management strategies for influenza under accelerated global change.
