Applying the Yb3+ ion as a simple and sensitive probe to detect phosphate-containing derivatives in aqueous solution

A simple and sensitive detection method for HPO(4)(2-) and phosphate-containing derivatives in aqueous solution with a new ensemble which is prepared by mixing ytterbium chloride and pyrocatechol violet in a 2:1 molar ratio in 10 mM HEPES buffer at pH 7.0.     

Black-Hole Entropy as Causal Links

We model a black hole spacetime as a causal set and count, with a certain definition, the number of causal links crossing the horizon in proximity to a spacelike or null hypersurface . We find that this number is proportional to the horizon's area on , thus supporting the interpretation of the links as the horizon atoms that account for its entropy. The cases studied include not only equilibrium black holes but ones far from equilibrium.     

Topological order in the insulating Josephson junction array

We propose a Josephson junction array which can be tuned into an unconventional insulating state by varying external magnetic field. This insulating state retains a gap to half-vortices; as a consequence, such an array with nontrivial global geometry exhibits a ground state degeneracy. This degeneracy is protected from the effects of external noise. We compute the gaps, separating higher energy states from the degenerate ground state, and we discuss experiments probing the unusual properties of this insulator.     

Analysis of the influence shifts of the acetylene of various effects on frequency saturated absorption lines

Frequency shifts of the acetylene saturated absorption lines at 1.5μm with temperature, gas pressure and laser power have been investigated in detail. The second-order Doppler effect, the recoil effect, the Zeeman effect, the pressure shift and the power shift are taken into consideration. The magnitudes of those shifts caused by various effects are evaluated. In order to reproduce the stability of 5.7 × 10^-14 obtained by Edwards, all necessary conditions are given. The results show that when there is a larger external magnetic field, the Zeeman shift could not be neglected, so that the shield should be employed. And the design of a long cavity is advantageous to reduce the influence of the second-order Doppler effect. The results also show that at least 4-2.5℃ temperature control for cavity can effectively prevent several effects and improve the frequency stability.     

Parameters optimization of high efficiency discrete Raman fiber amplifier by using the coupled steady-state equations

By using the coupled steady-state equations, we have numerically studied the characteristics optimization of Raman fiber amplifier (RFA) in a signal/pump double-passes-the-gain-medium scheme. The simulation results are in very good agreement with those of experimental data. Given a constant pumping power, the length of dispersion compensation fiber (DCF) in a RFA could be determined. The optimum design shows that the best length of the DCF is at around 3.8 ± 0.2 km in our study. This could provide both the highest signal output power and the lowest noise figure among all conditions we choose.     

被动差分光学吸收光谱法监测污染源排放总量研究

研究了一种测量污染源污染气体(如SO2、NO2)排放总量的光学遥测方法,即采用被动差分光学吸收光谱(DOAS)系统在移动平台(如汽车)上对污染源排放烟羽进行扫描测量,利用被动差分光学吸收光谱处理方法对系统采集的天顶太阳散射光谱进行处理获取柱密度,在结合测量时段的气象(风场)信息后获得污染气体的排放通量,最终得到排放总量。着重描述了获得烟羽垂直柱密度的差分光学吸收光谱方法以及污染气体排放通量的计算方法,并利用车载被动差分光学吸收光谱系统对某一热电厂SO2排放进行了外场测量,实验结果与在线设备的对比表明:这种基于被动差分光学吸收光谱光学遥测方法能够用于污染源排放总量的快速测量。     

tetracene 分子在Ru(1010)表面的吸附结构及其电子态研究

利用紫外光电子能谱(UPS)、角分辨紫外光电子能谱(ARUPS)和扫描隧道显微镜(STM)等方法研究了tetracene分子在Ru(1010)表面上吸附的电子态，吸附位置和吸附取向.UPS实验显示，与tetracene分子有关的光电子谱峰在费米能级以下2.1, 3.5, 4.8, 6.0, 7.1和9.2 eV处；ARUPS 结果表明，tetracene分子的分子平面基本平行于衬底表面；从STM图像中可以看到tetracene分子的长轴沿［0001］和［1210］两个晶向.基于密度泛函理论的从头算计算证实了上述结论.当分子长轴沿［0001］晶向时，分子中心位置在衬底表面的“短桥位”上，当分子长轴沿［1210］晶向时，分子中心位置在衬底表面的“四原子中心空位”上. 关键词： tetracene分子 Ru(1010)表面 吸附结构 吸附电子态     

Borderline magic clustering: the fabrication of tetravalent Pb cluster arrays on Si(111)-(7x7) surfaces

Well-ordered arrays of identical Pb clusters have been fabricated on a Si(111)-(7x7) substrate by the temperature-mediated surface clustering method. Interestingly, these clusters can easily transform into other forms when the growth temperature deviates slightly from the optimal values. In accord with experiments, first-principle total-energy calculations reveal several cluster structures centered on a mixed cluster model involving surface Pb and Si exchange. This borderline Pb/Si(111) system provides a unique, controlled way to study surface magic cluster formation and breakup dynamics.     

Incipient separation in shock wave/boundary layer interactions as induced by sharp fin

The incipient separation induced by the shock wave/turbulent boundary layer interaction at the sharp fin is the subject of the present study. Existing theories for the prediction of incipient separation, such as those put forward by McCabe (1966) and Dou and Deng (1992), can thus far only predic the direction of surface streamline and tend to overpredict the incipient separation condition based on the Stanbrook’s criterion. In this paper, the incipient separation is first predicted with Dou and Deng (1992)’s theory and then compared with Lu and Settles’ (1990) experimental data. The physical mechanism of the incipient separation as induced by the shock wave/turbulent boundary layer interactions at sharp fin is explained via surface flow pattern analysis. Furthermore, the reason for the observed discrepancy between the predicted and experimental incipient separation conditions is clarified. It is found that when the wall-limiting streamlines behind the shock wave becomes aligned with one ray from the virtual origin as the strength of the shock wave increases, the incipient separation line is formed at which the wall-limiting streamline becomes perpendicular to the local pressure gradient. The formation of this incipient separation line is the beginning of the separation process. The effects of Reynolds number and Mach number on incipient separation are also discussed. Finally, a correlation for the correction of the incipient separation angle as predicted by the theory is also given.

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