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Search Results: 1 - 10 of 67790 matches for " Qing-Bo Yan "
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Analysis of the Influential Factors of Manufactured Products Intra-Industry Trade between China-South Korea and China’ Policy  [PDF]
Yan Li, Qing-Ling Dai, Qing-Bo Huang
Theoretical Economics Letters (TEL) , 2015, DOI: 10.4236/tel.2015.51016
Abstract: In recent years, the trading contact between China and South Korea has become more and more close. In the 21st anniversary of the establishment of diplomatic relations between China and South Korea 2013, China has become South Korea’s largest export market and largest import market. At the same time, South Korea has become China’s fourth largest exporter and second largest importer of foreign trade, which contributes to the rapid development of?manufactured products intra-industry trade between China and South Korea. This paper summarizes the development status of industrial manufactured products intra-industry trade between China and South Korea since 1992, and uses empirical analysis, then drawing a conclusion that the direct investment from South Korea to China, total merchandise trade between China and South Korea, and the economic development level of China have great influences on the level of intra-industry trade between China and South Korea, but the degree of the influence is different for different types of manufactured goods. Finally, this article proposes policy recommendations to promote the further development of manufactured products intra-industry trade between China and South Korea.
Structures, Electronic Properties, Spectroscopies and Hexagonal Monolayer Phase of a Family of Unconventional Fullerenes C64X4 (X = H; F;Cl;Br)
Qing-Bo Yan,Qing-Rong Zheng,Gang Su
Physics , 2008,
Abstract: A systematic first-principles study within density functional theory on the geometrical structures and electronic properties of unconventional fullerene C64 and its derivatives C64X4 (X = H; F;Cl;Br) has been performed. By searching through all 3465 isomers of C64, the ground state of C64 is found to be spherical shape with D2 symmetry, which differs from the parent cage of the recently synthesized C64H4 that is pear-shaped with C3v symmetry. We found that the addition of the halogen atoms like F;Cl;Br to the pentagon-pentagon fusion vertex of C64 cage could enhance the stability, forming the unconventional fullerenes C64X4. The Mulliken charge populations, LUMO-HOMO gap energies and density of states are calculated, showing that different halogen atoms added to C64 will cause remarkably different charge populations of the C64X4 molecule; the chemical deriving could enlarge the energy gaps and affect the electronic structures distinctly. It is unveiled that C64F4 is even more stable than C64H4, as the C-X bond energy of the former is higher than that of the latter. The computed spectra of C64H4 molecules agree well with the experimental data; the IR, Raman, NMR spectra of C64X4 (X = F;Cl;Br) are also calculated to stimulate further experimental investigations. Finally, it is uncovered by total energy calculations that C64X4 could form a stable hexagonal monolayer.
Face-Centered-Cubic B$_{80}$ Metal: Density functional theory calculations
Qing-Bo Yan,Qing-Rong Zheng,Gang Su
Physics , 2008, DOI: 10.1103/PhysRevB.77.224106
Abstract: By means of ab initio calculations within the density functional theory, we have found that B80 fullerenes can condense to form stable face-centered-cubic fcc solids. It is shown that when forming a crystal, B80 cages are geometrically distorted, the Ih symmetry is lowered to Th, and four boron-boron chemical bonds are formed between every two nearest neighbor B80 cages. The cohesive energy of B80 fcc solid is 0.23 eV/atom with respect to the isolated B80 fullerene. The calculated electronic structure reveals that the fcc B80 solid is a metal. The predicted solid phase would constitute a form of pure boron and might have diverse implications. In addition, a simple electron counting rule is proposed, which could explain the stability of B80 fullerene and the recently predicted stable boron sheet.
Crystalline and Electronic Structures of Molecular Solid C$_{50}$Cl$% _{10}$: First-Principles Calculation
Qing-Bo Yan,Qing-Rong Zheng,Gang Su
Physics , 2005, DOI: 10.1103/PhysRevB.73.165417
Abstract: A molecular solid C$_{50}$Cl$_{10}$ with possible crystalline structures, including the hexagonal-close-packed (hcp) phase, the face-centered cubic (fcc) phase, and a hexagonal monolayer, is predicted in terms of first-principles calculation within the density functional theory. The stable structures are determined from the total-energy calculations, where the hcp phase is uncovered more stable than the fcc phase and the hexagonal monolayer in energy per molecule. The energy bands and density of states for hcp and fcc C$_{50}$Cl$_{10}$ are presented. The results show that C$_{50}$Cl% $_{10}$ molecules can form either a hcp or fcc indirect-gap band insulator or an insulating hexagonal monolayer.
Half-Metallic Silicon Nanowires: Multiple Surface Dangling Bonds and Nonmagnetic Doping
Zhuo Xu,Qing-Bo Yan,Qing-Rong Zheng,Gang Su
Physics , 2009, DOI: 10.1103/PhysRevB.80.081306
Abstract: By means of first-principles density functional theory calculations, we find that hydrogen-passivated ultrathin silicon nanowires (SiNWs) along [100] direction with symmetrical multiple surface dangling bonds (SDBs) and boron doping can have a half-metallic ground state with 100% spin polarization, where the half-metallicity is shown quite robust against external electric fields. Under the circumstances with various SDBs, the H-passivated SiNWs can also be ferromagnetic or antiferromagnetic semiconductors. The present study not only offers a possible route to engineer half-metallic SiNWs without containing magnetic atoms but also sheds light on manipulating spin-dependent properties of nanowires through surface passivation.
T-Carbon: A Novel Carbon Allotrope
Xian-Lei Sheng,Qing-Bo Yan,Fei Ye,Qing-Rong Zheng,Gang Su
Physics , 2011, DOI: 10.1103/PhysRevLett.106.155703
Abstract: A structurally stable crystalline carbon allotrope is predicted by means of the first-principles calculations. This allotrope can be derived by substituting each atom in diamond with a carbon tetrahedron, and possesses the same space group Fd^1 3m as diamond, which is thus coined as T- carbon. The calculations on geometrical, vibrational and electronic properties reveal that T-carbon, with a considerable structural stability and a much lower density 1.50 g/cm3, is a semiconductor with a direct band gap about 3.0 eV, and has a Vickers hardness 61.1 GPa lower than diamond but comparable with cubic boron nitride. Such a form of carbon, once obtained, would have wide applications in photocatalysis, adsoption, hydrogen storage and aerospace materials.
Anisotropic intrinsic lattice thermal conductivity of phosphorene from first principles
Guangzhao Qin,Qing-Bo Yan,Zhenzhen Qin,Sheng-Ying Yue,Ming Hu,Gang Su
Physics , 2014, DOI: 10.1039/c4cp04858j
Abstract: Phosphorene, the single layer counterpart of black phosphorus, is a novel two-dimensional semiconductor with high carrier mobility and a large fundamental direct band gap, which has attracted tremendous interest recently. Its potential applications in nano-electronics and thermoelectrics call for a fundamental study of the phonon transport. Here, we calculate the intrinsic lattice thermal conductivity of phosphorene by solving the phonon Boltzmann transport equation (BTE) based on first-principles calculations. The thermal conductivity of phosphorene at $300\,\mathrm{K}$ is $30.15\,\mathrm{Wm^{-1}K^{-1}}$ (zigzag) and $13.65\,\mathrm{Wm^{-1}K^{-1}}$ (armchair), showing an obvious anisotropy along different directions. The calculated thermal conductivity fits perfectly to the inverse relation with temperature when the temperature is higher than Debye temperature ($\Theta_D = 278.66\,\mathrm{K}$). In comparison to graphene, the minor contribution around $5\%$ of the ZA mode is responsible for the low thermal conductivity of phosphorene. In addition, the representative mean free path (MFP), a critical size for phonon transport, is also obtained.
Family of boron fullerenes: general constructing schemes, electron counting rule and ab initio calculations
Qing-Bo Yan,Xian-Lei Sheng,Qing-Rong Zheng,Li-Zhi Zhang,Gang Su
Physics , 2008, DOI: 10.1103/PhysRevB.78.201401
Abstract: A set of general constructing schemes is unveiled to predict a large family of stable boron monoelemental, hollow fullerenes with magic numbers 32+8k (k>=0). The remarkable stabilities of these new boron fullerenes are then studied by intense ab initio calculations. An electron counting rule as well as an isolated hollow rule are proposed to readily show the high stability and the electronic bonding property, which are also revealed applicable to a number of newly predicted boron sheets and nanotubes.
Superstructures of Cubic and Hexagonal Diamonds Comprising a Family of Novel $sp^3$ Superhard Carbon Allotropes
Hui-Juan Cui,Xian-Lei Sheng,Qing-Bo Yan,Qing-Rong Zheng,Gang Su
Physics , 2013,
Abstract: Superstructures of cubic and hexagonal diamonds (h- and c-diamond) comprising a family of stable diamond-like $sp^3$ hybridized novel carbon allotropes are proposed, which are referred to as U$_n$-carbon where $n \geq 2$ denotes the number of structural layers in a unit cell. The conventional h- and c-diamond are included in this family as members with $n=2$ and 3, respectively. U$_n$-carbon ($n=4-6$), which are unveiled energetically and thermodynamically more stable than h-diamond and possess remarkable kinetic stabilities, are shown to be insulators with indirect gaps of $5.6 \sim 5.8$ eV, densities of $ 3.5 \sim 3.6$ g/cm$^3$, bulk modulus of $4.3 \sim 4.4 \times 10^{2}$ GPa, and Vickers hardness of $92.9 \sim 97.5$ GPa even harder than h- and c-diamond. The simulated x-ray diffraction and Raman spectra are presented for experimental characterization. These new structures of carbon would have a compelling impact in physics, chemistry, materials science and geophysics.
Strain-induced Dirac cone-like electronic structures and semiconductor-semimetal transition in graphdiyne
Hui-Juan Cui,Xian-Lei Sheng,Qing-Bo Yan,Qing-Rong Zheng,Gang Su
Physics , 2012, DOI: 10.1039/c3cp44457k
Abstract: By means of the first-principles calculations combined with the tight-binding approximation, the strain-induced semiconductor-semimetal transition in graphdiyne is discovered. It is shown that the band gap of graphdiyne increases from 0.47 eV to 1.39 eV with increasing the biaxial tensile strain, while the band gap decreases from 0.47 eV to nearly zero with increasing the uniaxial tensile strain, and Dirac cone-like electronic structures are observed. The uniaxial strain-induced changes of the electronic structures of graphdiyne come from the breaking of geometrical symmetry that lifts the degeneracy of energy bands. The properties of graphdiyne under strains are disclosed different remarkably from that of graphene.
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