9,057 research outputs found
The stability and the shape of the heaviest nuclei
In this paper, we report a systematic study of the heaviest nuclei within the
relativistic mean field (RMF) model. By comparing our results with those of the
Hartree-Fock-Bogoliubov method (HFB) and the finite range droplet model (FRDM),
the stability and the shape of the heaviest nuclei are discussed. The
theoretical predictions as well as the existing experimental data indicate that
the experimentally synthesized superheavy nuclei are in between the fission
stability line, the line connecting the nucleus with maximum binding energy per
nucleon in each isotopic chain, and the -stability line, the line
connecting the nucleus with maximum binding energy per nucleon in each isobaric
chain. It is shown that both the fission stability line and the
-stability line tend to be more proton rich in the superheavy region.
Meanwhile, all the three theoretical models predict most synthesized superheavy
nuclei to be deformed.Comment: 6 pages, 7 figures, to appear in Journal of Physics
A Study on the Critical Thickness of the Inner Tube for Magnetic Pulse Welding Using FEM and BEM
Due to high efficiency and quality in welding dissimilar metals, Magnetic Pulse Welding
(MPW) has attracted much attention. In this study, 3A21 aluminium alloy used as outer
tube was welded to 20Fe tube by MPW. In order to investigate the critical thickness of the
inner tube (20Fe) which is subjected to huge impact pressure from the outer tube (3A21),
both numerical simulations and experiments were carried out.
For the purpose of investigating the critical thickness of the inner tube under various
impact velocities, four discharge voltages (9 kV, 11 kV, 13 kV and 14 kV) were employed
in the MPW experiment. The diameters of inner tube at different locations were measured
to obtain its plastic deformation at various discharge voltages. The simulations
considering the coupled effects of the mechanical, thermal and electromagnetic process
were performed to research the impact velocity and deformation of tubular fittings in the
electromagnetic module (EM) in LS-DYNA. An inverse method was proposed to find the
dynamic yield stress of inner tube, and the predicted yield stress was then employed in
models with critical thickness. Both of the impact velocity and deformation were verified
experimentally
Study of Radiative Leptonic D Meson Decays
We study the radiative leptonic meson decays of D^+_{(s)}\to
\l^+\nu_{\l}\gamma (\l=e,\mu,\tau), and D^0\to
\l^+\l^-\gamma () within the light front quark model. In the standard
model, we find that the decay branching ratios of , and
are (), (), and
(), and that of D^0\to\l^+\l^-\gamma (\l=e,\mu) and
are and ,
respectively.Comment: 23 pages, 6 Figures, LaTex file, a reference added, to be published
in Mod. Phys. Lett.
A systematic study of Zr and Sn isotopes in the Relativistic Mean Field theory
The ground-state properties of Zr and Sn isotopes are studied within the
relativistic mean field theory. Zr and Sn isotopes have received tremendous
attention due to various reasons, including the predicted giant halos in the
neutron-rich Zr isotopes, the unique feature of being robustly spherical in the
region of Sn Sn and the particular interest of Sn
isotopes to nuclear astrophysics. Furthermore, four (semi-) magic neutron
numbers, 40, 50, 82 and 126, make these two isotopic chains particularly
important to test the pairing correlations and the deformations in a
microscopic model. In the present work, we carry out a systematic study of Zr
and Sn isotopes from the proton drip line to the neutron drip line with
deformation effects, pairing correlations and blocking effects for nuclei with
odd number of neutrons properly treated. A constrained calculation with
quadrupole deformations is performed to find the absolute minimum for each
nucleus on the deformation surface. All ground-state properties, including the
separation energies, the odd-even staggerings, the nuclear radii, the
deformations and the single-particle spectra are analyzed and discussed in
detail.Comment: the final version to appear in Modern Physics Letters A. more
figures, discussions, and references added. the data remain unchange
Spurious Shell Closures in the Relativistic Mean Field Model
Following a systematic theoretical study of the ground-state properties of
over 7000 nuclei from the proton drip line to the neutron drip line in the
relativistic mean field model [Prog. Theor. Phys. 113 (2005) 785], which is in
fair agreement with existing experimental data, we observe a few spurious shell
closures, i.e. proton shell closures at Z=58 and Z=92. These spurious shell
closures are found to persist in all the effective forces of the relativistic
mean field model, e.g. TMA, NL3, PKDD and DD-ME2.Comment: 3 pages, to appear in Chinese Physics Letter
Sticking coefficient for dissociative adsorption of N<sub>2</sub> on Ru single‐crystal surfaces
The dissociative chemisorption of N2 on Ru(0001), Ru(101̄0), and Ru(112̄1) surfaces at 300 K was studied by means of high‐resolution electron energy loss spectroscopy and thermal desorption spectroscopy. The initial sticking coefficient was determined to s0=(1±0.8)×10−12, within the limits of error independent of surface orientation. On Ru(101̄0) and Ru(112̄1) small amounts of N can be dissolved into the subsurface region
Effects of recombinant human nerve growth factor on cervical cancer
Nerve growth factor (NGF) plays a crucial role in the life of the sympathetic and sensory nervous systems. However, the roles of NGF to cervical cancer remain deeply unknown. This study investigated the effect of recombinant human nerve growth factor (rhNGF) on cervical cancer. It was found that the proliferation of hela cells was inhibited by rhNGF and there were some apoptotic-like cell deaths. After tumor modeling of mice implanted U14 cells, it was shown that the growth of tumor tissues was inhibited in response to rhNGF and the concentration of virus been rhNGF was not more than 1.0×107 pfu/ml. In addition, the immune abilities of thymus and spleen were improved by rhNGF. Finally, it was shown that SOD level of tumor tissues was improved under the right concentration of rhNGF. Therefore, the mentioned result showed that cervical cancer is probably treated by rhNGF, which is depended on the concentration of rhNGF.Key words: rhNGF, cervical cancer, tumor inhibition
Optical properties of coupled metal-semiconductor and metal-molecule nanocrystal complexes: the role of multipole effects
We investigate theoretically the effects of interaction between an optical
dipole (semiconductor quantum dot or molecule) and metal nanoparticles. The
calculated absorption spectra of hybrid structures demonstrate strong effects
of interference coming from the exciton-plasmon coupling. In particular, the
absorption spectra acquire characteristic asymmetric lineshapes and strong
anti-resonances. We present here an exact solution of the problem beyond the
dipole approximation and find that the multipole treatment of the interaction
is crucial for the understanding of strongly-interacting exciton-plasmon
nano-systems. Interestingly, the visibility of the exciton resonance becomes
greatly enhanced for small inter-particle distances due to the interference
phenomenon, multipole effects, and electromagnetic enhancement. We find that
the destructive interference is particularly strong. Using our exact theory, we
show that the interference effects can be observed experimentally even in the
exciting systems at room temperature.Comment: 9 page
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