Ground state properties of a Bose－Einstein condensate confined in an anharmonic external potential

In light of the interference experiment of Bose－Einstein condensates, we present an anharmonic external potential model to study ground state properties of Bose－Einstein condensates. The ground state energy and the chemical potential have been analytically obtained, which are lower than those in harmonic trap. Additionally, it is found that the anharmonic strength of the external potential has an important effect on density and velocity distributions of the ground state for the Thomas－Fermi model.     

Electronic structure of Yb/H－Si (111) interface

Photoemission spectra are measured for Yb covered surface of wet-chemically-etched H－Si (111). The results reveal that the lattice structure of the H－Si (111) surface is stable against the deposition of Yb atoms. X-ray photoemission spectra indicate the formation of a polarized (dipole) surface layer, with the silicon negatively charged. Ultraviolet photoemission spectra exhibit the semiconducting property of the interface below one monolayer coverage. Work function variation during the formation of the Yb/H－Si (111) interface is measured by the secondary-electron cutoff in the ultraviolet photoemission spectral line. The largest decrease of work function is ～1.65eV. The contributions of the dipole surface layer and the band bending to the work function change are determined to be ～1.15eV and ～0.5eV, respectively. The work function of metal Yb is determined to be ～2.80±0.05eV.     

Comprehensive research about the cooperative up-conversion luminescence of the ytterbium-doped oxyfluoride vitroceramics

The cooperative up-conversion blue luminescence of Yb^{3+} ion-doped oxyfluoride vitroceramic material (Yb:FOV) and the influence of co-doped Ho^{3+} ion, when excited by a 960 nm diode-laser, are studied in this paper. A strong blue 479.1 nm up-conversion luminescence of the Yb:FOV material is discovered. It is found that the 479.1 nm luminescence results from the cooperative up-conversion of the coupled states of the Yb^{3+}－Yb^{3+} clusters formed by two adjacent Yb^{3+} ions. The measured cooperative up-conversion luminescence main peak 479.1 nm of this paper is different from the characteristic fluorescence main peak of the Tb^{3+} ion positioned at about 495－504 nm wave-range. Our result coincides with all the published correct papers, whose cooperative up-conversion luminescence main peaks of the direct Yb^{3+}－Yb^{3+} clusters are all positioned at about 476－480 nm wave-range. All of these indicate that the large cooperative up-conversion blue luminescence of the direct Yb^{3+}－Yb^{3+} clusters discovered in this paper is stable. It further proves that the cooperative up-conversion green luminescence may result from the Yb^{3+}-Tb^{3+} cooperative effect. In particular, the original work of this paper improves considerably on the traditional concept by the experimental facts that the blue 479.1 nm cooperative up-conversion luminescence strength of Yb(5):FOV is 230 times greater than that of fluoride glass Yb(3):ZBLAN. This is a great development to meet the practical requirements for blue up-conversion luminescence strength. This result indicates that the large cooperative up-conversion blue luminescence could be achieved excellently by using a suitable material, such as oxyfluoride vitroceramic, which provides a better chance to form better Yb^{3+}－Yb^{3+} clusters and has less relaxation to keep the more efficient up-conversion luminescence. It is also found that impurities seriously reduce the cooperative up-conversion luminescence intensity due to the cross-relaxation from the Yb^{3+}－Yb^{3+} clusters, which means that the cooperative up-conversion blue luminescence could be further improved by pure Yb^{3+} ion-doped materials that have as few impurities as possible to reduce the cross-relaxation. The large cooperative up-conversion blue luminescence of Yb(5):FOV also comes from its higher concentration (5 mol%) of activator Yb^{3+} ion which acts well because the cooperative up-conversion blue luminescence intensity varies linearly against the square of the concentration of Yb^{3+} ions in the range of 0.5－5 mol%. In summary, the great improvement of our work on cooperative up-conversion blue luminescence results from the comprehensive enhancement of the factors of better-coupled chance of the Yb^{3+}－Yb^{3+} clusters, less cross-relaxation, better concentration contribution of Yb^{3+} activator, non-saturation, and better up-conversion luminescence efficiency.     

Bound states of the Klein－Gordon and Dirac equations for scalar and vector harmonic oscillator potentials

We give the exact bound states of the Klein－Gordon and Dirac equations with equal scalar and vector harmonic oscillator potentials.     

Fabrication and optical properties of platinum nanowire arrays on anodic aluminium oxide templates

Arrays of Pt nanowires, fabricated by electrodepositing Pt metal into nanoporous anodic aluminium oxide (AAO) templates, exhibit a preferable optical absorption band in the ultraviolet-visible (UV-VIS) spectra and present a blueshift as the wire aspect ratio increases or its radius decreases. This type of optical property of Pt nanowire/porous alumina composites has been theoretically explored using Maxwell－Garnett (MG) effective medium theory. The MG theory, however, is only applicable to nanowires with an infinitesimally small radius relative to the wavelength of an incident light. The nanowire radius is controlled by the pore radius of the host alumina, which depends on anodizing conditions such as the selected electrolyte, anodizing time, temperature and voltage. The nanowire aspect ratios depend on the amount of Pt deposited into the nanopores of AAO films. The optical absorption properties of the arrays of Pt nanowires with diameters of 24, 55 and 90 nm have been investigated by the UV-VIS spectra, which show that the extinction maximum (λ_max) shifts to shorter wavelength side as the wire aspect ratio increases or its radius decreases. The results are qualitatively consistent with those calculated based on the MG theory.     

Effects of nickel on the crystallization of Zr70Cu20Ni10 amorphous alloy

Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) are employed to investigate the effects of nickel on the crystallization of the amorphous Zr₇₀Cu₂₀Ni₁₀ alloy. We have found that the crystallization process of the amorphous Zr₇₀Cu₂₀Ni₁₀ alloy is strongly influenced by the addition of nickel. Addition of 10 at% Ni to the Zr₇₀Cu₃₀ amorphous alloy makes the crystallization process proceed from a single-stage mode to a double-stage mode. The activation energy for crystallization of the amorphous Zr₇₀Cu₂₀Ni₁₀ alloy is calculated to be about 388kJ·mol^-1 on the basis of the Kissinger equation. The effects of nickel on the crystallization of the amorphous Zr₇₀Cu₂₀Ni₁₀ alloy are discussed in terms of the genetics of metals.     

Biosensors Based on Ion-Sensitive Field-Effect Transistors for HLA and MICA Antibody Detection in Kidney Transplantation

This work demonstrates the ability of the Ion-Sensitive Field-Effect Transistor (ISFET)-based immunosensor to detect antibodies against the human leukocyte antigen (HLA) and the major histocompatibility complex class-I-related chain A (MICA). The sensing membrane of the ISFET devices was modified and functionalized using an APTES-GA strategy. Surface properties, including wettability, surface thickness, and surface topology, were assessed in each module of the modification process. The optimal concentrations of HLA and MICA proteins for the immobilization were 10 and 50 μg/mL. The dose-response curve showed a detection range of 1.98–40 µg/mL for anti-HLA and 5.17–40 µg/mL for anti-MICA. The analytical precision (%CV) was found to be 10.69% and 8.92% for anti-HLA and -MICA, respectively. Moreover, the electrical signal obtained from the irrelevant antibody was considerably different from that of the specific antibodies, indicating the specific binding of the relevant antibodies without noise interference. The sensitivity and specificity in the experimental setting were established for both antibodies (anti-HLA: sensitivity = 80.00%, specificity = 86.36%; anti-MICA: sensitivity = 86.67%, specificity = 88.89%). Our data reveal the potential of applying the ISFET-based immunosensor to the detection of relevant anti-HLA and -MICA antibodies, especially in the field of kidney transplantation.     

通过不同烷基链取代调控喹吖啶酮分子在Ag(110)表面上的自组织结构

采用低能电子衍射、扫描隧道显微镜、第一性原理密度泛函理论计算以及分子力学计算,分别对不同烷基链取代的喹吖啶酮(QA)分子在Ag(110)基底上的吸附和生长进行了研究.QA和Ag基底的相互作用主要来自分子中O原子和Ag基底的共价键,它决定了分子的取向和最优吸附位置;而烷基链决定了分子吸附层的取向,QA分子间的排列可以通过烷基链的长度来调节.由此借助调节烷基链的长度,能够可控地制备具有不同物理性质的单层分子薄膜.     

光子晶体垂直腔面发射850nm波长激光器研究

文章报道了国内首次研制成功的光子晶体垂直腔面发射850nm波长激光器, 实现了连续电注入激射.发现器件能否激射直接依赖于光子晶体结构参数,而激光器的阈值、输出功率、输出模式等与光子晶体的晶格常数、占空比、腔的大小等因素有关.     

大气温度起伏谱的测量

用直径1μm和10μm金属丝分别测量了大气温度起伏功率谱,提出了测量湍流外尺度的方法。实测结果表明：在复杂的光传输路径上至少有50%的温度谱不符合Kolmogorov的－5/3定律;用直径1μm丝进行单点测量的C2n和直径10μm丝进行双点测量的C2n较为一致;80%的外尺度不超过7m。