817 research outputs found
Theoretical studies on structural and decay properties of superheavy nuclei
In this manuscript, we analyze the structural properties of
superheavy nuclei in the mass range of 284 A 375 within the
framework of deformed relativistic mean field theory (RMF) and calculate the
binding energy, radii, quadrupole deformation parameter, separation energies
and density profile. Further, a competition between possible decay modes such
as decay, decay and spontaneous fission (SF) of the isotopic
chain of superheavy nuclei under study is systematically analyzed
within self-consistent relativistic mean field model. Moreover, our analysis
confirmed that decay is restricted within the mass range 284 A
296 and thus being the dominant decay channel in this mass range.
However, for the mass range 297 A 375 the nuclei are unable to
survive fission and hence SF is the principal mode of decay for these isotopes.
There is no possibility of decay for the considered isotopic chain. In
addition, we forecasted the mode of decay 119 as one chain
from 119 and 119, two consistent chains from
119 and 119, three consistent chains from 119
and 119, four consistent alpha chains from 119, six consistent
alpha chains from 119. Also from our analysis we inferred that for
the isotopes Bh both decay and SF are equally
competent and can decay via either of these two modes. Thus, such studies can
be of great significance to the experimentalists in very near future for
synthesizing superheavy nuclei.Comment: 14 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1611.00232, arXiv:1704.0315
Structural and decay properties of superheavy nuclei
In this paper, we analyze the structural properties of and
superheavy nuclei within the ambit of axially deformed relativistic mean-field
framework with NL parametrization and calculate the total binding
energies, radii, quadrupole deformation parameter, separation energies, density
distributions. We also investigate the phenomenon of shape coexistence by
performing the calculations for prolate, oblate and spherical configurations.
For clear presentation of nucleon distributions, the two-dimensional contour
representation of individual nucleon density and total matter density has been
made. Further, a competition between possible decay modes such as
-decay, -decay and spontaneous fission of the isotopic chain of
superheavy nuclei with within the range 312 A 392 and 318
A 398 for is systematically analyzed within self-consistent
relativistic mean field model. From our analysis, we inferred that the
-decay and spontaneous fission are the principal modes of decay in
majority of the isotopes of superheavy nuclei under investigation apart from
decay as dominant mode of decay in isotopes.Comment: 16 pages, 10 figures , 8 table
Charged gravastars admitting conformal motion
We propose a new model of a {\it gravastar} admitting conformal motion. While
retaining the framework of the Mazur-Mottola model, the gravastar is assumed to
be internally charged, with an exterior defined by a Reissner-Nordstr{\"o}m
rather than a Schwarzschild line element. The solutions obtained involve (i)
the interior region, (ii) the shell, and (iii) the exterior region of the
sphere. Of these three cases the first case is of primary interest since the
total gravitational mass vanishes for vanishing charge and turns the total
gravitational mass into an {\it electromagnetic mass} under certain conditions.
This suggests that the interior de Sitter vacuum of a charged gravastar is
essentially an electromagnetic mass model that must generate the gravitational
mass. We have also analyzed various other aspects such as the stress energy
tensor in the thin shell and the entropy of the system.Comment: Minor addition, Accepted in Phys. Lett.
Magnetic damping of a carbon nanotube NEMS resonator
A suspended, doubly clamped single wall carbon nanotube is characterized at
cryogenic temperatures. We observe specific switching effects in dc-current
spectroscopy of the embedded quantum dot. These have been identified previously
as nano-electromechanical self-excitation of the system, where positive
feedback from single electron tunneling drives mechanical motion. A magnetic
field suppresses this effect, by providing an additional damping mechanism.
This is modeled by eddy current damping, and confirmed by measuring the
resonance quality factor of the rf-driven nano-electromechanical resonator in
an increasing magnetic field.Comment: 8 pages, 3 figure
Phenomenological Lambda-Nuclear Interactions
Variational Monte Carlo calculations for (ground and
excited states) and are performed to decipher information on
-nuclear interactions. Appropriate operatorial nuclear and
-nuclear correlations have been incorporated to minimize the
expectation values of the energies. We use the Argonne two-body
NN along with the Urbana IX three-body NNN interactions. The study demonstrates
that a large part of the splitting energy in () is
due to the three-body NN forces. hypernucleus is
analyzed using the {\it s}-shell results. binding to nuclear matter
is calculated within the variational framework using the
Fermi-Hypernetted-Chain technique. There is a need to correctly incorporate the
three-body NN correlations for binding to nuclear matter.Comment: 18 pages (TeX), 2 figure
Development and Evaluation of Orally Disintegrating Tablets of Montelukast Sodium by Direct Compression Method
Purpose: To design an orally disintegrating montelukast sodium tablet (ODT) that disintegrates in the oral cavity leaving an easy-to-swallow residue especially for pediatric and elderly patients who have difficulty swallowing tablets.Methods: Two different formulations of montelukast sodium (5 mg) orally disintegrating tablets were designed and manufactured by direct compression method, using microcrystalline (Avicel PH-102), mannitol, sodium bicarbonate, crospovidone and magnesium stearate as key excipients, and with cherry flavor and aspartame as flavor and sweetener, respectively. These formulations were then evaluated using pharmacopoeial and non-pharmacopoeial physical and chemical tests. Dissolution and assay tests were performed using USP apparatus II and ultraviolet (UV) spectrophotometry, respectively. Formulations with better results were further subjected for optimization study using central composite design method.Results: The results of prototype formulation batch (Trial-02) and the finest optimization formulation batch (FOB-01) reflected the successful development of new formulation of orally disintegrating montelukast sodium 5 mg tablet by direct compression technique. The value of similarity factor (f2 > 50), indicating that both formulations have similar drug release profiles. The formulations were further evaluated for three and six months under accelerated conditions to ascertain their stability.Conclusion: The results obtained demonstrate the suitability of the formulation as an ODT for convenient delivery of montelukast sodium for asthmatic patients. However, clinical studies are required to confirm this.Keywords: Orally disintegrating tablets, Asthma, Disintegration, Dissolution, Montelukast sodiu
- …