Decomposition of Noncommutative U(1) Gauge Potential

We investigate the decomposition of noncommutative gauge potential (A) over cap (i), and find that it has inner structure, namely, (A) over cap (i) can he decomposed in two parts, (b) over cap (i) and (a) over cap (i), where (b) over cap (i) satisfies gauge transformations while (a) over cap (i) satisfies adjoint transformations, so close the Seiberg-Witten mapping of noncommutative, U(1) gauge potential. By, means of Seiberg-Witten mapping, we construct a mapping of unit vector field between noncommutative space and ordinary space, and find the noncommutative U(1) gauge potential and its gauge field tensor can be expressed in terms of the unit vector field. When the unit vector field has no singularity point, noncommutative gauge potential and gauge field tensor will equal ordinary gauge potential and gauge field tensor

Experimental study of the U-238(S-36,3-5n)(269-271)Hs reaction leading to the observation of (270)Hs

The deformed doubly magic nucleus (270)Hs has so far only been observed as the four-neutron (4n) evaporation residue of the reaction Mg-26+Cm-248, where a maximum cross section of 3 pb was measured. Theoretical studies on the formation of (270)Hs in the 4n evaporation channel of fusion reactions with different entrance channel asymmetry in the framework of a two-parameter Smoluchowski equation predict that the reactions Ca-48+Ra-226 and S-36+U-238 result in higher cross sections due to lower reaction Q values, in contrast to simple arguments based on the reaction asymmetry, which predict opposite trends. Calculations using HIVAP predict cross sections for the reaction S-36+U-238 that are similar to those of the Mg-26+Cm-248 reaction. Here, we report on the first measurement of evaporation residues formed in the complete nuclear fusion reaction S-36+U-238 and the observation of (270)Hs, which is produced in the 4n evaporation channel, with a measured cross section of 0.8(-0.7)(+2.6) pb at 51-MeV excitation energy. The one-event cross-section limits (68% confidence level) for the 3n, 4n, and 5n evaporation channels at 39-MeV excitation energy are 2.9 pb, while the cross-section limits of the 3n and 5n channel at 51 MeV are 1.5 pb. This is significantly lower than the 5n cross section of the Mg-26+Cm-248 reaction at similar excitation energy.

Studies of K-shell x-ray energy shifts induced by MeV/u heavy ions

This paper reports that the K x-ray spectra of the thin target 47Ag, 48Cd, 49In and 50Sn were measured by an HPGe semi-conductor detector in collisions with 84.5 MeV 6C4+ ions. Our experiment revealed the Kα x-ray energy shifts were not obvious and the Kβ1 x-ray energy shifts were about 90∼110 eV. The simple model of Burch et al has been previously used to calculate the K x-ray energy shifts due to an additional vacancy in 2p orbit. The present work extends the model of Burch to calculate the x-ray energy shifts of multiple ionized atoms induced by heavy ions with kinetic energy of MeV/u. In addition to our experimental results, many other experimental results are compared with the calculated values by using the model.

Dynamics of collapsing fluidized beds and its application in the simulation of pulsed fluidized beds

A new method to study collapsing process of fluidized bed was proposed. The method is based on the analysis of the pressure variation during collapse. A model is proposed to describe the pressure variation on any location of the bed during collapse. Three kind of particles were fluidized by air and the pressure variation after shutting down the gas supply was measured by pressure transducers and simulated by the proposed model. The simulated results were in good agreement with the experimental data. The parameters of the fluidized bed, such as bubble fraction alpha(b), particle fraction in dense phase alpha(p), bubble velocity u(b) and slip velocity of particle u(i), can be estimated from the measured pressure data by using the proposed model. The model was also used to calculate the pressure variation in pulsed fluidized beds with low frequency.

Studies of magnetic interactions in Ni-doped ZnO from first-principles calculations

The magnetic interactions in Ni-doped ZnO are calculated using GGA and GGA + U method of density functional theory. The following three cases: (i) Ni-doped ZnO, (ii) (Ni, Al)-codoped ZnO, and (iii) (Ni, Li)-codoped ZnO are studied. The ferromagnetic ordering is always favorable for the three cases within GGA method. However, the ferromagnetic state is sometimes favorable after treating within the method of GGA + U. The GGA underestimates the correlated interactions especially when the Ni ions align directly to each other. (C) 2007 Elsevier B.V. All rights reserved.

Tentative study of the coding sequences without 3-base periodicity

Fourier spectra of 120 short coding sequences (<1 200 bp) show that not all coding sequences are characterized by 3-base periodicity. Statistical analysis suggests that whether a coding sequence has 3-base periodicity may be related to the composition and distribution of bases, the usage and the order of the amino acids of the encoded protein as well as the synonymous codon usage. Generally, the content of A+U is higher than that of G+C in non-period-3 sequences, inversely in period-3 sequences. In the three codon positions, the base distribution in the non-periodic-3 sequences is more uniform than in the periodic-3 sequences. The usage biases of the amino acids and the codons in non-period-3 sequences are weaker than that in period-3 sequences. All of these phenomena should be considered sufficiently in predicting the genes and exons of DNA sequences by Fourier analysis method.

Structure and Electronic Properties of Saturated and Unsaturated Gallium Nitride Nanotubes

The atomic and electronic structures of saturated and unsaturated GaN nanotubes along the [001] direction with (100) lateral facets are studied using first-principles calculations. Atomic relaxation of nanotubes shows that appreciable distortion occurs in the unsaturated nanotubes. All the nanotubes considered, including saturated and unsaturated ones, exhibit semiconducting, with a direct band gap Surface states arisen from the 3-fold-coordinated N and Ga atoms at the lateral facets exist inside the bulklike band gap. When the nanotubes are saturated with hydrogen, these dangling bond bands are removed from the band gap, but the band gap decreases with increasing the wall thickness of the nanotubes.

SHEAR-DEFORMATION-POTENTIAL CONSTANT OF THE CONDUCTION-BAND MINIMA OF SI - EXPERIMENTAL-DETERMINATION BY THE DEEP-LEVEL CAPACITANCE TRANSIENT METHOD

The shear-deformation-potential constant XI-u of the conduction-band minima of Si has been measured by a method which we called deep-level capacitance transient under uniaxial stress. The uniaxial-stress (F) dependence of the electron emission rate e(n) from deep levels to the split conduction-band minima of Si has been analyzed. Theoretical curves are in good agreement with experimental data for the S0 and S+ deep levels in Si. The values of XI-u obtained by the method are 11.1 +/- 0.3 eV at 148.9 K and 11.3 +/- 0.3 eV at 223.6 K. The analysis and the XI-u values obtained are also valuable for symmetry determination of deep electron traps in Si.

Measurement of total reaction cross section for neutron-rich nucleus Li-11 on Si-28 target at medium energy

The neutron-rich nucleus Li-11 is separated by the radioactive ion beam line RIBLL at HIRFL from the breakup of 50MeV/u C-13 on Be target. The total reaction cross sections for Li-11 at energies range from 25 to 45MeV/u on Si target have been measured by using the transmission method. The experimental data at high and low energies can be fitted well by Glauber model using two Gauss density distribution. The matter radius of Li-11 was also deduced.

Measurement of neutron-removal cross section of neutron-rich nucleus He-8 by using the transmission method

The neutron-rich nucleus He-8 is selected by RIBLL from the breakup of 50MeV/u C-13 on be target at HIRFL. The 2n-removal and 4n-removal cross section of He-8 was measured by using the transmission method. The point that He-4 is He-8 core can be reduced from the experiment data via the Ogawa's theory.

Studies of soluble human catalytic antibody with glutathione peroxidase activity

By screening the phage-displayed human single chain antibody library, we have got the specific single chain antibody bound to GSH-S-DNP butyl ester as the hapten. The tertiary structure of the protein was analyzed with the aid of computer, and the results showed the CDR3 region located on the surface of the antibody. The soluble antibody was expressed in E. coli. and the active site serine was converted into selenocysteine with the chemical modifying method, which resulted in the catalytic antibody with GPx activity of 80 U/mu mol. Furthermore, the same Ping-Pong mechanism as the natural GPx was observed when the kinetic behavior of the antibody was studied.