112号元素问世

一个由欧洲科学家组成的国际研究小组发现了一种新的化学元素,使世人已知的化学元素总数达到了112种。该研究小组的科学家们历尽艰辛,在为期三个星期的最新实验中,使用一种机器,向一个用铅元素制作的目标发射高能原子,这些高能原子的速度加快到恰好足以能与铅原子融合的程度。当然,产生这种融合的概率极小,约为一万亿分之一,就是说了获得原子反应,必须发射1万亿次。

美选定空间站首次科学实验项目

美航宇局(NASA)选定在自由号国际空间站上首次进行科学实验的14个项目,预定在1996年实施,其实验内容与承接单位如下: ·宇宙尘埃实验——华盛顿大学; ·激光通信用无线电收发两用机——哥达德空间中心; ·大面积标准阵列反射镜/高性能X射线观测仪——史密松天体物理观测所;

Stable High-Energy Density Super-Atom Clusters of Aluminum Hydride

With the concept of super-atom, first principles calculations propose a new type of super stable cage clusters AlnH3n that are much more energetic stable than the well established clusters, AlnHn＋2. In the new clusters, the aluminum core-frame acts as a super-atom with n vertexes and 2n A1-A1 edges, which allow to adsorb n hydrogen atoms at the top-site and 2n at the bridge-site. Using Al12H36 as the basic unit, stable chain structures, （Al12H36）m, have been constructed following the same connection mechanism as for （A1H3）n linear polymeric structures. Apart from high hydrogen percentage per molecule, calculations have shown that these new clusters possess large heat of formation values and their combustion heat is about 4.8 times of the methane, making them a promising high energy density material.

A Helium Atom Confined by a Spherical Gaussian Potential Well

The helium atom confined by a non-impenetrable spherical box, i.e., a spherical Gaussian potential well which possesses finite height and range, is studied employing the exact diagonalization method. Total energies of the ground and three low-excited states are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. The results for the three-dimensional spherical potential well and the two-dimensional disc-like potential well are compared with each other： in general, the energies of the states decrease and the energy intervals between states increase with the reduction of the space dimensions.

High-Speed Generation of Entangled States for Two Three-Level Atoms

A scheme is presented for generating entangled states for two three-level atoms in a cavity. In the scheme two atoms simultaneously interact with a cavity mode with a small detuning. Thus, the operation time is very short, which is important in view of decoherence.

In situ Heating and Thermal Effects in Auger Electron Spectroscopy for GaN

An in situ heating system was built for the Auger electron spectroscopy to investigate the thermal effect of Auger lines. A GaN sample was studied in this system. The kinetic energy of Ga LMM and MVV Auger lines were observed to shift negatively with temperature increasing. By using ab initio calculation, the theoretical Ga MVV Auger line shape was fit, which well reflects the inner property of the line. The Auger shift with heating is related with the valence electron rearrangement in the thermal expansion of the local bonds.

High-selective removal of ultra-low level mercury ions from aqueous solution using oligothymonucleic acid functionalized polyethylene film

We prepare oligothymonucleic acid (OTA) functionalized polyethylene (PE) film and evaluate its selective removal ability of mercury ions at ultra-low levels in aqueous solution. The selective binding of OTA with mercury ions is confirmed by fluorescence in situ hybridization (FISH). The quantitative results via cold-vapor atomic fluorescence spectrometry (CVAFS) indicate that OTA-functionalized PE film is able to remove mercury ions at the sub-ppb level selectively from aqueous solution, even with the coexistence of other metal ions at concentrations 250-fold or higher than that of mercury.

First-Principles GGA+U Study of Intermediate-Band Characters from Zn_(1-x)M_xO(M=3d Transition-Metal) Alloys Suitable for High Efficiency Solar Cell

The electronic structure characters are calculated for the Zn1-∞MxO alloys with some Zn atoms in ZnO substituted by 3d transition-metal atoms （M）, in order to find out which of these alloys could provide an intermediate band material used for fabricating high efficiency solar cell. Especially, among of these alloys, the electronic structure character and optical performance of Zn1-xCr∞ 0 alloys clearly show an intermediate band filled partially and isolated from the VB and the CB in energy band structure of ZnO host, and the intermediate band characters can be preserved with increasing Cr concentrations no more than 8.33% in Zn1-xCrxO alloys, at the same time, the ratio 0.52 of Eg^FC to EVE in Zn1-xCrxO, （x = 4.16%） alloy is closest to the optimal ratio of 0,57. Besides, compared to the ZnO, the optical absorption does indicate a great improved absorption below the calculated band gap of the ZnO and an enhancement of the optical absorption in the whole solar spectral energy range.