Superhydrophobic surfaces via controlling the morphology of ZnO micro/nano complex structure

ZnO micro/nano complex structure films, including reticulate papillary nodes, petal-like and flake-hole, have been self-assembled by a hydrothermal technique at different temperatures without metal catalysts. The wettability of the above film surfaces was modified with a simple coating of heptadecafluorodecyltrimethoxy-silane in toluene. After modifying, the surface of ZnO film grown at 50~${^\circ}$C was converted from superhydrophilic with a water contact angle lower than 5$^{\circ}$ to superhydrophobic with a water contact angle of 165$^{\circ}$. Additionally, the surface of reticulate papillary nodes ZnO film grown at 100~${^\circ}$C had excellent superhydrophobicity, with a water contact angle of 173$^{\circ}$ and a sliding angle lower than 2$^{\circ}$. Furthermore, the water contact angle on the surface of petal-like and flake-hole ZnO films grown at 150~${^\circ}$C and 200~${^\circ}$C were found to be 140$^{\circ}$ and 120$^{\circ}$, respectively. The wettability for the samples was found to depend strongly on the surface morphology which results from the growth temperature.     

The fabrication of nickel silicide ohmic contacts to n-type 6H-silicon carbide

This paper reports that the nickel silicide ohmic contacts to n-type 6H-SiC have been fabricated. Transfer length method test patterns with NiSi/SiC and NiSi硅化镍;欧姆触点;n型碳化硅;制造;能带;带隙Project supported by the National Basic Research Program of China (Grant No~2002CB311904), the National Defense Basic Research Program of China (Grant No~51327010101) and the National Natural Science Foundation of China (Grant No~60376001).2006-09-192006-10-30This paper reports that the nickel silicide ohmic contacts to n-type 6H-SiC have been fabricated. Transfer length method test patterns with NiSi/SiC and NiSi2/SiC structure axe formed on N-wells created by N^＋ ion implantation into Si-faced p-type 6H-SiC epilayer respectively. NiSi and NiSi2 films are prepared by annealing the Ni and Si films separately deposited. A two-step annealing technology is performed for decreasing of oxidation problems occurred during high temperature processes. The specific contact resistance Pc of NiSi contact to n-type 6H-SiC as low as 1.78× 10^-6Ωcm^2 is achieved after a two-step annealing at 350 ℃for 20 min and 950℃ for 3 min in N2. And 3.84×10-6Ωcm^2 for NiSi2 contact is achieved. The result for sheet resistance Rsh of the N＋ implanted layers is about 1210Ω/□. X-ray diffraction analysis shows the formation of nickel silicide phases at the metal/n-SiC interface after thermal annealing. The surfaces of the nickel silicide after thermal annealing are analysed by scanning electron microscope.     

Effects of concentration and annealing on the performance of regioregular poly（3-hexylthiophene） field-effect transistors

This paper investigates the effects of concentration on the crystalline structure, the morphology, and the charge carrier mobility of regioregular poly(3-hexylthiophene) (RR-P3HT) field-effect transistors (FETs). The RR-P3HT FETs with RR-P3HT as an active layer with different concentrations of RR-P3HT solution from 0.5~wt% to 2~wt% are prepared. The results indicate that the performance of RR-P3HT FETs improves drastically with the increase of RR-P3HT weight percentages in chloroform solution due to the formation of more microcrystalline lamellae and bigger nanoscale islands. It finds that the field-effect mobility of RR-P3HT FET with 2~wt% can reach 5.78× 10^-3~cm²/Vs which is higher by a factor of 13 than that with 0.5~wt%. Further, an appropriate thermal annealing is adopted to improve the performance of RR-P3HT FETs. The field-effect mobility of RR-P3HT FETs increases drastically to 0.09~cm²/Vs by thermal annealing at 150~℃, and the value of on/off current ratio can reach 10^4.     

Electron tunnelling phase time and dwell time through an associated delta potential barrier

The electron tunnelling phase time τP and dwell time τD through an associated delta potential barrier U(x) = ξδ(x) are calculated and both are in the order of 10^-17～10^-16s. The results show that the dependence of the phase time on the delta barrier parameter ξ can be described by the characteristic length lc = h^2/meξ and the characteristic energy Ec=meξ^2/h^2 of the delta barrier, where me is the electron mass, lc and Ec are assumed to be the effective width and height of the delta barrier with lcEc=ξ, respectively. It is found that TD reaches its maximum and τD = τp as the energy of the tunnelling electron is equal to Ec/2, i.e. as lc =λDB, λDB is de Broglie wave length of the electron.     

Study of the FCNH Coupling with Boosted Higgs at LHC*

We present a study about the flavor changing coupling of the top quark with the Higgs boson through the channel $pp\to H t/\bar{t}$ with $H\to b\bar{b}$ at LHC. The final states considered for the such process are $l^\pm+\mathbb{E}_{T}+3b$. We focus on the boosted region in the phase space of the Higgs boson. The backgrounds and events are simulated and analyzed. The sensitivities for the FCNH couplings are estimated. It is found that it is more sensitive for $y_{\rm tu}$ than $y_{\rm tq}$ at LHC. The upper limits of the FCNH couplings can be set at LHC with 3000 ${\rm fb}^{-1}$ integrated luminosity as $\vert y_{\rm tu}\vert^2=1.1\times10^{-3}$ and $\vert y_{\rm tc}\vert^2=7.2\times 10^{-3}$ at 95% C.L.     

Characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection

We study the characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh–Benard convection in′a square cavity by direct numerical simulations.The Rayleigh number range is 1×10⁸≤Ra≤1×10¹³,and the Prandtl number is selected as Pr=0.7 and Pr=4.3.It is found that the temperature fluctuation profiles with respect to Ra exhibit two different distribution patterns.In the thermal boundary layer,the normalized fluctuationθrms/θrms,max is independent of Ra and a power law relation is identified,i.e.,θrms/θrms,max～(z/δ)0.99±0.01,where z/δis a dimensionless distance to the boundary(δis the thickness of thermal boundary layer).Out of the boundary layer,when Ra≤5×10⁹,the profiles ofθrms/θrms,max descend,then ascend,and finally drop dramatically as z/δincreases.While for Ra≥1×10¹⁰,the profiles continuously decrease and finally overlap with each other.The two different characteristics of temperature fluctuations are closely related to the formation of stable large-scale circulations and corner rolls.Besides,there is a critical value of Ra indicating the transition,beyond which the fluctuation hθrmsiV has a power law dependence on Ra,given by hθrmsiV～Ra?0.14±0.01.     

Co-Al-W基高温合金的团簇成分式

Co-Al-W基高温合金具有类似于Ni基高温合金的γ+γ'相组织结构.根据面心立方固溶体的团簇加连接原子结构模型,Ni基高温合金的成分式即最稳定的化学近程序结构单元可以描述为第一近邻配位多面体团簇加上次近邻的三个连接原子.本文应用类似方法,首次给出了Co-Al-W基高温合金的团簇成分式.利用原子半径和团簇共振模型,可计算出Co-Al-W三元合金的团簇成分通式,为[Al-Co_(12)](Co,Al,W)_3,即以Al为中心原子、Co为壳层原子的[Al-Co_(12)]团簇加上三个连接原子.对于多元合金,需要先将元素进行分类:溶剂元素——类Co元素Co (Co, Cr, Fe, Re, Ni,Ir,Ru)和溶质元素——类Al元素Al (Al,W,Mo, Ta,Ti,Nb,V等);进而根据合金元素的配分行为,将类Co元素分为Co~γ(Cr, Fe, Re)和Co~(γ')(Ni, Ir, Ru);根据混合焓,将类Al元素分为Al, W (W, Mo)和Ta (Ta, Ti, Nb, V等).由此,任何多元Co-Al-W基高温合金均可简化为Co-Al伪二元体系或者Co-Al-(W,Ta)伪三元体系,其团簇加连接原子成分式为[Al-Co_(12)](Co_(1.0)Al_(2.0))(或[Al-Co_(12)] Co_(1.0)Al_(0.5)(W,Ta)_(1.5)=Co_(81.250)Al_(9.375)(W,Ta)_(9.375) at.%).其中,γ与γ'相的团簇成分式分别为[Al-Co_(12)](Co_(1.5)Al_(1.5))(或[Al-Co_(12)] Co_(1.5)Al_(0.5)(W,Ta)_(1.0)=Co_(84.375)Al_(9.375)(W,Ta)_(6.250) at.%)和[Al-Co_(12)](Co_(0.5)Al_(2.5))(或[Al-Co_(12)] Co_(0.5)Al_(0.5)(W, Ta)_(2.0)=Co_(78.125)Al_(9.375)(W,Ta)_(12.500)at.%).例如,Co_(82)Al_9W_9合金的团簇成分式为[Al-Co_(12)]Co_(1.1)Al_(0.4)W_(1.4)(～[Al-Co_(12)]Co_(1.0)Al_(0.5)W_(1.5)),其中γ相的团簇成分式为[Al-Co_(12)]Co_(1.6)Al_(0.4)W_(1.0)(～[Al-Co_(12)]Co_(1.5)Al_(0.5)W_(1.0)),γ'相的团簇成分式为[Al-Co_(12)]Co_(0.3)Al_(0.5)W_(2.2)(～[AlCo_(12)]Co_(0.5)Al_(0.5)W_(2.0)).     

Searching for isotropic stochastic gravitational-wave background in the international pulsar timing array second data release

We search for isotropic stochastic gravitational-wave background (SGWB) in the International Pulsar Timing Array second data release. By modeling the SGWB as a power-law, we find very strong Bayesian evidence for a common-spectrum process, and further this process has scalar transverse (ST) correlations allowed in general metric theory of gravity as the Bayes factor in favor of the ST-correlated process versus the spatially uncorrelated common-spectrum process is 30 ± 2. The median and the 90% equal-tail amplitudes of ST mode are ${{ \mathcal A }}_{\mathrm{ST}}={1.29}_{-0.44}^{+0.51}\times {10}^{-15}$, or equivalently the energy density parameter per logarithm frequency is ${{\rm{\Omega }}}_{\mathrm{GW}}^{\mathrm{ST}}={2.31}_{-1.30}^{+2.19}\times {10}^{-9}$, at frequency of 1 year⁻¹. However, we do not find any statistically significant evidence for the tensor transverse (TT) mode and then place the 95% upper limits as ${{ \mathcal A }}_{\mathrm{TT}}\lt 3.95\times {10}^{-15}$, or equivalently ${{\rm{\Omega }}}_{\mathrm{GW}}^{\mathrm{TT}}\lt 2.16\times {10}^{-9}$, at frequency of 1 year⁻¹.     

Two-electron and one-photon transitions in highly charged nickel-like ions

This paper calculates the transition wavelengths and probabilities of the two-electron and one-photon (TEOP) transition from the $(3{\rm s}^{-1}_{1/2}4{\rm d}_{j})_{J=1,2}$ to $(3{\rm p}^{-1}_{3/2}4{\rm s}_{1/2})_{J=1}$ and the $(3{\rm p}^{-1}_{1/2}4{\rm s}_{1/2})_{J=1}$ to $(3{\rm d}^{-1}_{j}4{\rm d}_{j'})_{J=1,2}$ for highly charged Ni-like ions with atomic number $Z$ in the range $47\leq Z\leq92$. In the calculations, the multi-configuration Dirac--Fock method and corresponding program packages GRASP92 and REOS99 were used, and the relativistic effects, correlation effects and relaxation effects were considered systematically. It is found that the TEOP transitions are very sensitive to the correlation of electrons, and the probabilities will be enhanced sharply in some special $Z$ regions along the isoelectronic sequence. The present TEOP transition wavelengths are compared with the available data from some previous publications, good agreement is obtained.     

Hyperfine structure and isotope shifts in near-infrared transitions of atomic nitrogen

We have obtained Doppler-free spectra of transitions in the → 2p²(³P) and → multiplets of atomic nitrogen using saturated absorption spectroscopy. These multiplets consist of respectively of seven and eight transitions, and have center of gravity wavelengths of 821 nm and 869 nm. Values for the hyperfine structure coupling constants of all the upper and lower states for these multiplets were obtained for both ¹⁴N and ¹⁵N. Isotope shifts of three transitions in each multiplet were also measured, and a significant J-dependence to the shifts was observed.     

用H-W-ECR CVD系统实现氢化非晶硅薄膜在氢气环境下同时进行化学热退火和光诱导退火的研究

为了研究氢化非晶硅薄膜的稳定性，我们设计了一个在原子氢气氛中热退火的同时进行光诱导退火的实验(TLAH)。实验装置是由传统的微波电子回旋共振化学气相沉积系统改造而成为热丝辅助微波电子回旋共振化学气相沉积系统。为了对这一退火方法进行比较，对样品还进行了热退火、热退火同时进行光诱导退火。同时，为了定量地分析光电导衰退，我们假设光电导衰退遵循扩展指数规律：1/σph=1/σs-(1/σs-1/σ0)exp[-(t/τ)β]，这里扩展指数参数β 和时间常数 τ 可从与 lnt 的线性关系中截距和斜率得到, 式中光电导饱和值σs可以通过在对数坐标系中表示的光电导和光照时间关系进行高斯拟合得到。实验结果显示：TLAH 方法可以提高氢化非晶硅薄膜的稳定性、改善其微结构和光电特性，同时还发现，光学带隙明显减小、荧光光谱显著地朝着低能方向移动。     

The splitting of low-lying states for hydroxyl molecule under spin--orbit coupling

The splitting of potential energy curves for the states $X^{2}\Pi _{3/2}$, $^{2}\Pi _{1/2}$ and $A^{2}\Sigma ^{ +}$ of hydroxyl OH under spin--orbit coupling (SOC) has been calculated by using the SO multi-configuration quasi-degenerate perturbation theory (SO-MCQDPT). Their Murrell--Sorbie (M--S) potential functions have been derived, then, the spectroscopic constants for $X^{2}\Pi _{3/2}$,$^{ 2}\Pi _{1/2}$ and $A^{2}\Sigma ^{ + }$ have been derived from the M--S function. The calculated dissociation energies for the three states are $D_{0}$[OH($X^{2}\Pi _{3/2})$]=34966.632cm$^{-1}$, $D_{0}$[OH($^{2}\Pi _{1/2})$]=34922.802cm$^{-1}$, and $D_{0}$[OH($A^{2}\Sigma ^{ + })$]=17469.794cm$^{-1}$, respectively. The vertical excitation energy $\nu [ {{ }^2\Pi _{1/2} ( {\nu = 0} ) \to {X}{ }^2\Pi _{3/2} ( {\nu = 0} )} ] = 139.6{\rm cm}^{-{\rm 1}}$. All the spectroscopic data for the $X^{2}\Pi _{3/2}$ and $^{2}\Pi _{1/2 }$ are given for the first time except the dissociation energy of $X^{2}\Pi _{3/2}$.     

Parity-violating neutron spin rotation in hydrogen and deuterium

We calculate the (parity-violating) spin-rotation angle of a polarized neutron beam through hydrogen and deuterium targets, using pionless effective field theory up to next-to-leading order. Our result is part of a program to obtain the five leading independent low-energy parameters that characterize hadronic parity violation from few-body observables in one systematic and consistent framework. The two spin-rotation angles provide independent constraints on these parameters. Our result for np spin rotation is $\frac{1} {\rho }\frac{{d\varphi _{PV}^{np} }} {{dl}} = \left[ {4.5 \pm 0.5} \right] rad MeV^{ - \frac{1} {2}} \left( {2g^{\left( {^3 S_1 - ^3 P_1 } \right)} + g^{\left( {^3 S_1 - ^3 P_1 } \right)} } \right) - \left[ {18.5 \pm 1.9} \right] rad MeV^{ - \frac{1} {2}} \left( {g_{\left( {\Delta {\rm I} = 0} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} - 2g_{\left( {\Delta {\rm I} = 2} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} } \right)$\frac{1} {\rho }\frac{{d\varphi _{PV}^{np} }} {{dl}} = \left[ {4.5 \pm 0.5} \right] rad MeV^{ - \frac{1} {2}} \left( {2g^{\left( {^3 S_1 - ^3 P_1 } \right)} + g^{\left( {^3 S_1 - ^3 P_1 } \right)} } \right) - \left[ {18.5 \pm 1.9} \right] rad MeV^{ - \frac{1} {2}} \left( {g_{\left( {\Delta {\rm I} = 0} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} - 2g_{\left( {\Delta {\rm I} = 2} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} } \right), while for nd spin rotation we obtain $\frac{1} {\rho }\frac{{d\varphi _{PV}^{nd} }} {{dl}} = \left[ {8.0 \pm 0.8} \right] rad MeV^{ - \frac{1} {2}} g^{\left( {^3 S_1 - ^1 P_1 } \right)} + \left[ {17.0 \pm 1.7} \right] rad MeV^{ - \frac{1} {2}} g^{\left( {^3 S_1 - ^3 P_1 } \right)} + \left[ {2.3 \pm 0.5} \right] rad MeV^{ - \frac{1} {2}} \left( {3g_{\left( {\Delta {\rm I} = 0} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} - 2g_{\left( {\Delta {\rm I} = 1} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} } \right)$\frac{1} {\rho }\frac{{d\varphi _{PV}^{nd} }} {{dl}} = \left[ {8.0 \pm 0.8} \right] rad MeV^{ - \frac{1} {2}} g^{\left( {^3 S_1 - ^1 P_1 } \right)} + \left[ {17.0 \pm 1.7} \right] rad MeV^{ - \frac{1} {2}} g^{\left( {^3 S_1 - ^3 P_1 } \right)} + \left[ {2.3 \pm 0.5} \right] rad MeV^{ - \frac{1} {2}} \left( {3g_{\left( {\Delta {\rm I} = 0} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} - 2g_{\left( {\Delta {\rm I} = 1} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} } \right), where the g ^(X-Y), in units of $MeV^{ - \frac{3} {2}}$MeV^{ - \frac{3} {2}}, are the presently unknown parameters in the leading-order parity-violating Lagrangian. Using naıve dimensional analysis to estimate the typical size of the couplings, we expect the signal for standard target densities to be $\left| {\frac{{d\varphi _{PV} }} {{dl}}} \right| \approx \left[ {10^{ - 7} \ldots 10^{ - 6} } \right]\frac{{rad}} {m}$\left| {\frac{{d\varphi _{PV} }} {{dl}}} \right| \approx \left[ {10^{ - 7} \ldots 10^{ - 6} } \right]\frac{{rad}} {m} for both hydrogen and deuterium targets. We find no indication that the nd observable is enhanced compared to the np one. All results are properly renormalized. An estimate of the numerical and systematic uncertainties of our calculations indicates excellent convergence. An appendix contains the relevant partial-wave projectors of the three-nucleon system.     

High energy electron radiation effect on Ni/4H-SiC SBD and Ohmic contact

The Ni/4H-SiC Schottky barrier diodes (SBDs) and transfer length method (TLM) test patterns of Ni/4H-SiC Ohmic contacts were fabricated, and irradiated with 1~MeV electrons up to a dose of 3.43× 10¹⁴~e/cm^-2. After radiation, the forward currents of the SBDs at 2~V decreased by about 50%, and the reverse currents at -200~V increased by less than 30%. Schottky barrier height (φ _B ) of the Ni/4H-SiC SBD increased from 1.20~eV to 1.21~eV under 0~V irradiation bias, and decreased from 1.25~eV to 1.19~eV under -30~V irradiation bias. The degradation of φ _B could be explained by the variation of interface states of Schottky contacts. The on-state resistance (R_s) and the reverse current increased with the dose, which can be ascribed to the radiation defects in bulk material. The specific contact resistance (\rho_c) of the Ni/SiC Ohmic contact increased from 5.11× 10⁵~Ωega.cm² to 2.97× 10^-4~Ωega.cm².     

Kiselev黑洞的热力学性质和物质吸积特性

本文考虑带有黑洞视界和宇宙视界的Kiselev时空.研究以黑洞视界和宇宙视界为边界的系统的热力学性质.统一地给出了两个系统的热力学第一定律;在黑洞视界半径远小于宇宙视界半径的情况下,近似地计算了通过宇宙视界和黑洞视界的热能.然后,探讨Kiselev时空的物质吸积特性.在吸积能量密度正比于背景能量密度的条件下给出黑洞的吸积率,讨论了黑洞吸积率与暗能量态方程参数的关系.     

Chirality-asymmetry force between ɑ-quartz and copper block

The chirality-asymmetry macroscopic force mediated by light pseudoscalar particles between α -quartz and some achiral matter is studied. If this force between achiral source mass and α -quartz with some chirality is attractive, it will become repulsive when the chirality of the α -quartz crystal is changed. According to the tested limits of the coupling constant g_s g_p /\hbar c< 1.5× 10^-24 at the Compton wavelength λ = 10^-3 m, the force (F) between a 0.08× 0.08× 0.002 m³ block of α -quartz and a 0.08× 0.08× 0.01 m³ copper block with a separation being 0.5× 10^-3 \mbox{m} in between, is estimated from the published data at less than 4.64× 10^-24 N, i.e. F < 4.64× 10^-24 N.     

Central black hole mass determination for blazars

In this paper, we use a method to determine some basic parameters for the $\gamma$-ray loud blazars. The parameters include the central black mass ($M$), the boosting factor ($\delta$), the propagation angle (${\it {\it\Phi}}$), the distance along the axis to the site of the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray loud blazars with available variability time scales has been used to discuss the above properties. In this method, the $\gamma$-ray energy, the emission size and the property of the accretion disc determine the absorption effect. If we take the intrinsic $\gamma$-ray luminosity to be $\lambda$ times the Eddington luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we have the following results: the mass of the black hole is in the range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or $(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting factor ($\delta$) in the range of In this paper, we use a method to determine some basic parameters for the $\gamma$-ray loud blazars. The parameters include the central black mass ($M$), the boosting factor ($\delta$), the propagation angle (${\it {\it\Phi}}$), the distance along the axis to the site of the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray loud blazars with available variability time scales has been used to discuss the above properties. In this method, the $\gamma$-ray energy, the emission size and the property of the accretion disc determine the absorption effect. If we take the intrinsic $\gamma$-ray luminosity to be $\lambda$ times the Eddington luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we have the following results: the mass of the black hole is in the range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or $(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting factor ($\delta$) in the range of In this paper, we use a method to determine some basic parameters for the $\gamma$-ray loud blazars. The parameters include the central black mass ($M$), the boosting factor ($\delta$), the propagation angle (${\it {\it\Phi}}$), the distance along the axis to the site of the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray loud blazars with available variability time scales has been used to discuss the above properties. In this method, the $\gamma$-ray energy, the emission size and the property of the accretion disc determine the absorption effect. If we take the intrinsic $\gamma$-ray luminosity to be $\lambda$ times the Eddington luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we have the following results: the mass of the black hole is in the range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or $(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting factor ($\delta$) in the range of In this paper, we use a method to determine some basic parameters for the $\gamma$-ray loud blazars. The parameters include the central black mass ($M$), the boosting factor ($\delta$), the propagation angle (${\it {\it\Phi}}$), the distance along the axis to the site of the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray loud blazars with available variability time scales has been used to discuss the above properties. In this method, the $\gamma$-ray energy, the emission size and the property of the accretion disc determine the absorption effect. If we take the intrinsic $\gamma$-ray luminosity to be $\lambda$ times the Eddington luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we have the following results: the mass of the black hole is in the range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or $(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting factor ($\delta$) in the range of In this paper, we use a method to determine some basic parameters for the $\gamma$-ray loud blazars. The parameters include the central black mass ($M$), the boosting factor ($\delta$), the propagation angle (${\it {\it\Phi}}$), the distance along the axis to the site of the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray loud blazars with available variability time scales has been used to discuss the above properties. In this method, the $\gamma$-ray energy, the emission size and the property of the accretion disc determine the absorption effect. If we take the intrinsic $\gamma$-ray luminosity to be $\lambda$ times the Eddington luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we have the following results: the mass of the black hole is in the range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or $(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting factor ($\delta$) in the range of $0.16-2.09(\lambda=1.0)$ or $0.24-2.86\ (\lambda=0.1)$; the angle (${\it\Phi}$) in the range of $9.53^{\circ}-73.85^{\circ}\ (\lambda=1.0)$ or $7.36^{\circ}-68.89^{\circ}\ (\lambda=0.1)$; and the distance ($d/R_{\rm g}$) in the range of $22.39-609.36\ (\lambda=1.0)$ or $17.54-541.88\ (\lambda=0.1)$.     

Constraints on $H_0$ from WMAP and BAO Measurements *

We report the constraints of $H_0$ obtained from Wilkinson Microwave Anisotropy Probe (WMAP) 9-year data combined with the latest baryonic acoustic oscillations (BAO) measurements. We use the BAO measurements from 6dF Galaxy Survey (6dFGS), the SDSS DR7 main galaxies sample (MGS), the BOSS DR12 galaxies, and the eBOSS DR14 quasars. Adding the recent BAO measurements to the cosmic microwave background (CMB) data from WMAP, we constrain cosmological parameters $\Omega_m=0.298\pm0.005$, $H_0=68.36^{+0.53}_{-0.52} {\rm km}\cdot {\rm s}^{-1}\cdot {\rm Mpc}^{-1}$, $\sigma_8=0.8170^{+0.0159}_{-0.0175}$ in a spatially flat $\Lambda$ cold dark matter ($\Lambda$CDM) model, and $\Omega_m=0.302\pm0.008$, $H_0=67.63\pm1.30 {\rm km}\cdot{\rm s}^{-1}\cdot {\rm Mpc}^{-1}$, $\sigma_8=0.7988^{+0.0345}_{-0.0338}$ in a spatially flat $w$CDM model, respectively. Our measured $H_0$ results prefer a value lower than 70 ${\rm km}\cdot {\rm s}^{-1}\cdot{\rm Mpc}^{-1}$, consistent with the recent data on CMB constraints from Planck (2018), but in $3.1$ and $3.5\sigma$ tension with local measurements of SH0ES (2018) in $\Lambda$CDM and $w$CDM framework, respectively. Our results indicate that there is a systematic tension on the Hubble constant between SH0ES and the combination of CMB and BAO datasets.     

Thermodynamic criterion for searching high mobility two-dimensional electron gas at KTaO_3 interface

Two-dimensional electron gases(2 DEGs) formed at the interface between two oxide insulators present a promising platform for the exploration of emergent phenomena.While most of the previous works focused on SrTiO_(3-)based 2 DEGs,here we took the amorphous-ABO_3/KTaO_3 system as the research object to study the relationship between the interface conductivity and the redox property of B-site metal in the amorphous film.The criterion of oxide-oxide interface redox reactions for the B-site metals,Zr,Al,Ti,Ta,and Nb in conductive interfaces was revealed:the formation heat of metal oxide,ⅢH_f~o,is lower than-350 kJ/(mol O) and the work function of the metal Φ is in the range of 3.75 eVΦ 4.4 eV.Furthermore,we found that the smaller absolute value of ⅢH_f~o and the larger value of Φ of the B-site metal would result in higher mobility of the two-dimensional electron gas that formed at the corresponding amorphous-ABO_3/KTaO_3 interface.This finding paves the way for the design of high-mobility all-oxide electronic devices.     

SF_6分子最高占据轨道对称性的判断

量化计算是理论研究分子的重要手段,对于具有高对称群的分子,采用子群计算是常用的方法.分子的电子态或分子轨道等的对称性在子群的表示中会出现重迭,从而不能从子群的结果直接给出电子态或分子轨道对称性的归属.本文以如何判断SF6基态1 A_(1g)的电子组态中最高占据轨道的对称性为例来解决这个问题.针对某些文献中的SF6基态1 A1g的电子组态中,最高占据轨道对称性是T_(1g)却写成T_(2g)的问题,采用Molpro量化计算软件,对SF6基态的平衡结构,进行了HF/6-311G*计算,得到了能量三重简并的最高占据轨道的函数表达式,进而运用O_h群的对称操作作用在三个轨道函数上,得到各操作的矩阵表示,于是得到特征标,最后确定了最高占据轨道为T_(1g)对称性.