Effects of lanthanum on microstructure and mechanical properties of ZL702 alloy at room and high temperature conditions are studied. The experiment shows that high temperature intermetallics reticularly distributing ...Effects of lanthanum on microstructure and mechanical properties of ZL702 alloy at room and high temperature conditions are studied. The experiment shows that high temperature intermetallics reticularly distributing at grain boundary are formed with La and Al, Si, Fe etc. elements of alloy, which enhances the thermal stability of the alloy. With appropriate content of La (0.10%～ 0.15%), the mechanical properties of the alloy, such as strength, at room temperature and high temperature can be improved.展开更多
MoSi 2 and rare earths/MoSi 2 materials were prepared by mechanical alloying, IP and high temperature sintering techniques. Their room temperature properties such as bending strength, fracture toughness and elect...MoSi 2 and rare earths/MoSi 2 materials were prepared by mechanical alloying, IP and high temperature sintering techniques. Their room temperature properties such as bending strength, fracture toughness and electric conductivity were measured. The results show that rare earths have better strengthening and toughening effects on the MoSi 2 matrix than SiC does. The room temperature bending strength and fracture toughness of 0 9% rare earths/MoSi 2 material are 419 41 MPa and 5 81 MPa·m 1/2 , which have increased by 46% and 81% than the matrix, respectively. The strengthening mechanisms of rare earths/MoSi 2 are fine grain and dispersion strengthening. The toughening mechanisms are fine grain toughening, crack deflection and bowing toughening. Moreover, the effect of rare earths on the electric conductivity of MoSi 2 is much weaker than that of SiC whiskers. With the addition of 0 9% rare earths, the resistivity of MoSi 2 is only raised by about 13 9%.展开更多
Al-doped zinc oxide（AZO） and Ga-doped zinc oxide（GZO） thin films with the same doping concentration（3.6 at%） were deposited on glass substrates at room temperature by direct current（DC） magnetron sputtering.Co...Al-doped zinc oxide（AZO） and Ga-doped zinc oxide（GZO） thin films with the same doping concentration（3.6 at%） were deposited on glass substrates at room temperature by direct current（DC） magnetron sputtering.Consequently,we comparatively studied the doped thin films on the basis of their structural,morphological,electrical,and optical properties for optoelectronic applications.Both thin films exhibited excellent optical properties with more than 85%transmission in the visible range.The GZO thin film had better crystallinity and smoother surface morphology than the AZO thin film.The conductivity of the GZO thin film was improved compared to that of the AZO thin film：the resistivity decreased from 1.01×10^-3 to 3.5×10^-4 Ω cm,which was mostly due to the increase of the carrier concentration from 6.5×10^20 to 1.46×10^21cm^-3.These results revealed that the GZO thin film had higher quality than the AZO thin film with the same doping concentration for optoelectronic applications.展开更多
Mismatch in mechanical properties can induce intimal hyperplasia,which is one of the main reasons for the failure of small diameter artificial blood vessels. Electrospun small diameter tubes with tailored mechanical p...Mismatch in mechanical properties can induce intimal hyperplasia,which is one of the main reasons for the failure of small diameter artificial blood vessels. Electrospun small diameter tubes with tailored mechanical properties were fabricated through blending poly( L-lactide-co-ε-caprolactone)( PLCL) and silk fibroin( SF)with the mass ratios of 30 /70,50 /50,and 70 /30 in this study.Scanning electron microscopy( SEM) and mechanical testing were used to characterize morphological and mechanical properties of the tubes. Results showed that tensile strength of the tubes was higher than most of the native blood vessels,and elongations at break of them were improved greatly by blending PLCL. Compliances of the tubes were all higher than 1% /13. 33 kPa( 1% /100 mmHg).Particularly,tubes with blending mass ratio of 50 /50 showed similar compliance with human native femoral arteries,which provided a promising biomaterial that could be applied on small diameter vascular applications.展开更多
Transport properties and the associated structural heterogeneity of room temperature aqueous ionic liquids and especially of super-concentrated electrolyte aqueous solutions have received increasing attention,due to t...Transport properties and the associated structural heterogeneity of room temperature aqueous ionic liquids and especially of super-concentrated electrolyte aqueous solutions have received increasing attention,due to their potential application in ionic battery.This paper briefly reviews the results reported mainly since 2010 about the liquid-liquid separation,aggregation of polar and apolar domains in neat RTILs,and solvent clusters and 3D networks chiefly constructed by anions in super-concentrated electrolyte solutions.At the same time,the dominating effect of desolvation process of metal ions at electrode/electrolyte interface upon the transport of metal ions is stressed.This paper also presents the current understanding of how water affects the anion-cation interaction,structural heterogeneities,the structure of primary coordination sheath of metal ions and consequently their transport properties in free water-poor electrolytes.展开更多
In this paper we investigate the nearly small twist mappings with intersection property. With a certain non-degenerate condition, we proved that the most of invariant tori of the original small twist mappings will sur...In this paper we investigate the nearly small twist mappings with intersection property. With a certain non-degenerate condition, we proved that the most of invariant tori of the original small twist mappings will survive afer small perturtations. The persisted invariant tori are close to the unperturbed ones when the perturbation are small. The orbits reduced by those mappings are quasi-periodic in the invariant tori with the frequences closing to the original ones.展开更多
The electronic and magnetic properties of small IrN clusters (N=5, 6, 9, 13, and 19 ) are studied by using the discrete-variational local-spin-density-functional method. The equilibrium bond length in the chosen geome...The electronic and magnetic properties of small IrN clusters (N=5, 6, 9, 13, and 19 ) are studied by using the discrete-variational local-spin-density-functional method. The equilibrium bond length in the chosen geometry for IrN clusters are determined and show bond contraction compared with the bulk interatomic spacing. The clusters with magnetic ground state have ferromagnetic interaction and their average magnetic moment per atom has a complex size dependence. At last, the reactivity of IrN clusters toward H2, N2 and CO molecules is predicted.展开更多
The quantum anomalous Hall(QAH) effect has attracted enormous attention since it can induce topologically protected conducting edge states in an intrinsic insulating material. For practical quantum applications, the m...The quantum anomalous Hall(QAH) effect has attracted enormous attention since it can induce topologically protected conducting edge states in an intrinsic insulating material. For practical quantum applications, the main obstacle is the non-existent room temperature QAH systems, especially with both large topological band gap and robust ferromagnetic order. Here, according to first-principles calculations, we predict the realization of the room temperature QAH effect in a two-dimensional(2D) honeycomb lattice, RuCS_(3) with a non-zero Chern number of C = 1. Especially, the nontrivial topology band gap reaches up to 336 me V for RuCS_(3). Moreover, we find that RuCS_(3) has a large magnetic anisotropy energy(2.065 me V) and high Curie temperature(696 K). We further find that the non-trivial topological properties are robust against the biaxial strain. The robust topological and magnetic properties make RuCS_(3) have great applications in room temperature spintronics and nanoelectronics.展开更多
TiO2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process, and were annealed at 500 ℃ and 800 ℃ in air for 2 hrs. X-ray diffraction （XRD） measurements indicate that the Mn-TiO...TiO2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process, and were annealed at 500 ℃ and 800 ℃ in air for 2 hrs. X-ray diffraction （XRD） measurements indicate that the Mn-TiO2 nano powders with Mn concentration of 1 at% and 2 at% annealed at 500 and 800 ℃ are of pure anatase and rutile, respectively. The scanning electron microscope （SEM） observations reveal that the crystal grain size increases with the annealing temperature, and the high resolution transmission electron microscopy （HRTEM） investigations further indicate that the samples are well crystallized, confirming that Mn has doped into the TiO2 crystal lattice effectively. The room temperature ferromagnetism, which could be explained within the scope of the bound magnetic polaron （BMP） theory, is detected in the Mn-TiO2 samples with Mn concentration of 2 at%, and the magnetization of the powders annealed at 500 ℃ is stronger than that of the sample treated at 800 ℃. The UV-VIS diffuse reflectance spectra results demonstrate that the absorption of the TiO2 powders could be enlarged by the enhanced trapped electron absorption caused by Mn doping.展开更多
This paper concerns the linearization problem on rational maps of degree d≥2 and polynomials of degree d>2 from the perspective of non-linearizability.The authors introduce a set l_(∞) of irrational numbers and s...This paper concerns the linearization problem on rational maps of degree d≥2 and polynomials of degree d>2 from the perspective of non-linearizability.The authors introduce a set l_(∞) of irrational numbers and show that if α∈l_(∞),then any rational map is not linearizable and has infinitely many cycles in every neighborhood of the fixed point with multiplier λ=e^(2πiα),Adding more constraints to cubic polynomials,they discuss the above problems by polynomial-like maps.For the family of polynomials,with the help of Yoccoz's method,they obtain its maximum dimension of the set in which the polynomials are non-linearizable.展开更多
文摘Effects of lanthanum on microstructure and mechanical properties of ZL702 alloy at room and high temperature conditions are studied. The experiment shows that high temperature intermetallics reticularly distributing at grain boundary are formed with La and Al, Si, Fe etc. elements of alloy, which enhances the thermal stability of the alloy. With appropriate content of La (0.10%～ 0.15%), the mechanical properties of the alloy, such as strength, at room temperature and high temperature can be improved.
文摘MoSi 2 and rare earths/MoSi 2 materials were prepared by mechanical alloying, IP and high temperature sintering techniques. Their room temperature properties such as bending strength, fracture toughness and electric conductivity were measured. The results show that rare earths have better strengthening and toughening effects on the MoSi 2 matrix than SiC does. The room temperature bending strength and fracture toughness of 0 9% rare earths/MoSi 2 material are 419 41 MPa and 5 81 MPa·m 1/2 , which have increased by 46% and 81% than the matrix, respectively. The strengthening mechanisms of rare earths/MoSi 2 are fine grain and dispersion strengthening. The toughening mechanisms are fine grain toughening, crack deflection and bowing toughening. Moreover, the effect of rare earths on the electric conductivity of MoSi 2 is much weaker than that of SiC whiskers. With the addition of 0 9% rare earths, the resistivity of MoSi 2 is only raised by about 13 9%.
基金Funded by National Natural Science Foundation of China(NSFC)(Nos.21205127,61275114)
文摘Al-doped zinc oxide（AZO） and Ga-doped zinc oxide（GZO） thin films with the same doping concentration（3.6 at%） were deposited on glass substrates at room temperature by direct current（DC） magnetron sputtering.Consequently,we comparatively studied the doped thin films on the basis of their structural,morphological,electrical,and optical properties for optoelectronic applications.Both thin films exhibited excellent optical properties with more than 85%transmission in the visible range.The GZO thin film had better crystallinity and smoother surface morphology than the AZO thin film.The conductivity of the GZO thin film was improved compared to that of the AZO thin film：the resistivity decreased from 1.01×10^-3 to 3.5×10^-4 Ω cm,which was mostly due to the increase of the carrier concentration from 6.5×10^20 to 1.46×10^21cm^-3.These results revealed that the GZO thin film had higher quality than the AZO thin film with the same doping concentration for optoelectronic applications.
基金National Natural Science Foundation of China(No.51103092)Natural Science Foundation of Jiangsu Province,China(No.BK2012634)
文摘Mismatch in mechanical properties can induce intimal hyperplasia,which is one of the main reasons for the failure of small diameter artificial blood vessels. Electrospun small diameter tubes with tailored mechanical properties were fabricated through blending poly( L-lactide-co-ε-caprolactone)( PLCL) and silk fibroin( SF)with the mass ratios of 30 /70,50 /50,and 70 /30 in this study.Scanning electron microscopy( SEM) and mechanical testing were used to characterize morphological and mechanical properties of the tubes. Results showed that tensile strength of the tubes was higher than most of the native blood vessels,and elongations at break of them were improved greatly by blending PLCL. Compliances of the tubes were all higher than 1% /13. 33 kPa( 1% /100 mmHg).Particularly,tubes with blending mass ratio of 50 /50 showed similar compliance with human native femoral arteries,which provided a promising biomaterial that could be applied on small diameter vascular applications.
基金the National Natural Science Foundation of China(Grant Nos.11974385 and 91956101)the Fund from the Chinese Academy of Sciences(Grant No.1731300500030)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB07030100).
文摘Transport properties and the associated structural heterogeneity of room temperature aqueous ionic liquids and especially of super-concentrated electrolyte aqueous solutions have received increasing attention,due to their potential application in ionic battery.This paper briefly reviews the results reported mainly since 2010 about the liquid-liquid separation,aggregation of polar and apolar domains in neat RTILs,and solvent clusters and 3D networks chiefly constructed by anions in super-concentrated electrolyte solutions.At the same time,the dominating effect of desolvation process of metal ions at electrode/electrolyte interface upon the transport of metal ions is stressed.This paper also presents the current understanding of how water affects the anion-cation interaction,structural heterogeneities,the structure of primary coordination sheath of metal ions and consequently their transport properties in free water-poor electrolytes.
文摘In this paper we investigate the nearly small twist mappings with intersection property. With a certain non-degenerate condition, we proved that the most of invariant tori of the original small twist mappings will survive afer small perturtations. The persisted invariant tori are close to the unperturbed ones when the perturbation are small. The orbits reduced by those mappings are quasi-periodic in the invariant tori with the frequences closing to the original ones.
基金Supported by theYouth Natural Science Foundation of Educational Bureau of Sichuan Province (No.212-114879)
文摘The electronic and magnetic properties of small IrN clusters (N=5, 6, 9, 13, and 19 ) are studied by using the discrete-variational local-spin-density-functional method. The equilibrium bond length in the chosen geometry for IrN clusters are determined and show bond contraction compared with the bulk interatomic spacing. The clusters with magnetic ground state have ferromagnetic interaction and their average magnetic moment per atom has a complex size dependence. At last, the reactivity of IrN clusters toward H2, N2 and CO molecules is predicted.
基金the Natural Science Foundation of Shandong Province, China (Grant No. ZR2019MA041)the Taishan Scholar Project of Shandong Province, China (Grant No. ts20190939)+1 种基金the National Natural Science Foundation of China (Grant No. 62071200)the Shandong Provincial Natural Science Foundation, China (Grant No. ZR2020QA052)。
文摘The quantum anomalous Hall(QAH) effect has attracted enormous attention since it can induce topologically protected conducting edge states in an intrinsic insulating material. For practical quantum applications, the main obstacle is the non-existent room temperature QAH systems, especially with both large topological band gap and robust ferromagnetic order. Here, according to first-principles calculations, we predict the realization of the room temperature QAH effect in a two-dimensional(2D) honeycomb lattice, RuCS_(3) with a non-zero Chern number of C = 1. Especially, the nontrivial topology band gap reaches up to 336 me V for RuCS_(3). Moreover, we find that RuCS_(3) has a large magnetic anisotropy energy(2.065 me V) and high Curie temperature(696 K). We further find that the non-trivial topological properties are robust against the biaxial strain. The robust topological and magnetic properties make RuCS_(3) have great applications in room temperature spintronics and nanoelectronics.
基金Project supported by the Innovation Foundation of BUAA for PhD Graduates (Grant No. 292122)Equipment Research Foundation of China
文摘TiO2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process, and were annealed at 500 ℃ and 800 ℃ in air for 2 hrs. X-ray diffraction （XRD） measurements indicate that the Mn-TiO2 nano powders with Mn concentration of 1 at% and 2 at% annealed at 500 and 800 ℃ are of pure anatase and rutile, respectively. The scanning electron microscope （SEM） observations reveal that the crystal grain size increases with the annealing temperature, and the high resolution transmission electron microscopy （HRTEM） investigations further indicate that the samples are well crystallized, confirming that Mn has doped into the TiO2 crystal lattice effectively. The room temperature ferromagnetism, which could be explained within the scope of the bound magnetic polaron （BMP） theory, is detected in the Mn-TiO2 samples with Mn concentration of 2 at%, and the magnetization of the powders annealed at 500 ℃ is stronger than that of the sample treated at 800 ℃. The UV-VIS diffuse reflectance spectra results demonstrate that the absorption of the TiO2 powders could be enlarged by the enhanced trapped electron absorption caused by Mn doping.
文摘This paper concerns the linearization problem on rational maps of degree d≥2 and polynomials of degree d>2 from the perspective of non-linearizability.The authors introduce a set l_(∞) of irrational numbers and show that if α∈l_(∞),then any rational map is not linearizable and has infinitely many cycles in every neighborhood of the fixed point with multiplier λ=e^(2πiα),Adding more constraints to cubic polynomials,they discuss the above problems by polynomial-like maps.For the family of polynomials,with the help of Yoccoz's method,they obtain its maximum dimension of the set in which the polynomials are non-linearizable.
