171 research outputs found
On χs-Orthogonal Matrices
In this paper we, introduced the concept of χs-orthogonal matrices and extended some results of Abaraetal, [3] in the context of secondary transpose
Quark Matter in Neutron Stars: An apercu
The existence of deconfined quark matter in the superdense interior of
neutron stars is a key question that has drawn considerable attention over the
past few decades. Quark matter can comprise an arbitrary fraction of the star,
from 0 for a pure neutron star to 1 for a pure quark star, depending on the
equation of state of matter at high density. From an astrophysical viewpoint,
these two extreme cases are generally expected to manifest different
observational signatures. An intermediate fraction implies a hybrid star, where
the interior consists of mixed or homogeneous phases of quark and nuclear
matter, depending on surface and Coulomb energy costs, as well as other finite
size and screening effects. In this brief review article, we discuss what we
can deduce about quark matter in neutron stars in light of recent exciting
developments in neutron star observations. We state the theoretical ideas
underlying the equation of state of dense quark matter, including color
superconducting quark matter. We also highlight recent advances stemming from
re-examination of an old paradigm for the surface structure of quark stars and
discuss possible evolutionary scenarios from neutron stars to quark stars, with
emphasis on astrophysical observations.Comment: 15 pages, 1 figure. Invited review for Modern Physics Letters
Neutrality of a magnetized two-flavor quark superconductor
We investigate the effect of electric and color charge neutrality on the
two-flavor color superconducting (2SC) phase of cold and dense quark matter in
presence of constant external magnetic fields and at moderate baryon densities.
Within the framework of the Nambu-Jona-Lasinio (NJL) model, we study the
inter-dependent evolution of the quark's BCS gap and constituent mass with
increasing density and magnetic field. While confirming previous results
derived for the highly magnetized 2SC phase with color neutrality alone, we
obtain new results as a consequence of imposing charge neutrality. In the
charge neutral gapless 2SC phase (g2SC), a large magnetic field drives the
color superconducting phase transition to a crossover, while the chiral phase
transition is first order. At larger diquark-to-scalar coupling ratio
, where the 2SC phase is preferred, we see hints of the
Clogston-Chandrasekhar limit at a very large value of the magnetic field
(G), but this limit is strongly affected by Shubnikov de
Haas-van Alphen oscillations of the gap, indicating the transition to a
domain-like state.Comment: 19 pages, 7 figures, Matches with the published versio
Surface structure of Quark stars with magnetic fields
We investigate the impact of magnetic fields on the electron distribution in
the electrosphere of quark stars. For moderately strong magnetic fields G, quantization effects are generally weak due to the large number
density of electrons at surface, but can nevertheless affect the spectral
features of quark stars. We outline the main observational characteristics of
quark stars as determined by their surface emission, and briefly discuss their
formation in explosive events termed Quark-Novae, which may be connected to the
-process.Comment: 9 pages, 3 figures. Contribution to the proceedings of the IXth
Workshop on High Energy Physics Phenomenology (WHEPP-9), Bhubaneswar, India,
3-14 Jan. 200
EFFECT OF FLAVONE AND ITS MONOHYDROXY DERIVATIVES ON ANIMAL MODELS OF DEPRESSION IN SWISS ALBINO MICE
Objectives: This research was designed to investigate the antidepressant activity of a few structurally related flavones (flavone, 3‑hydroxyflavone, and 7‑hydroxyflavone) and the possible mechanisms involved.
Methods: Antidepressant activity was evaluated in mice by subjecting them to forced swim test and tail suspension test. The involvement of adrenergic, serotonergic, nitric oxide (NO), and opioid mechanisms was investigated using suitable interacting chemicals.
Results: Flavone, 3‑hydroxyflavone, and 7‑hydroxyflavone exhibited a significant and dose‑dependent reduction in total time of immobility in the forced swim test and tail suspension test. Pre‑treatment with alpha‑methyl‑para‑tyrosine and parachlorophenyl alanine attenuated the reduction in immobility period produced by flavone and its derivatives in forced swim test. Naloxone pre‑treatment partially reversed the effect of flavone while L‑arginine pre‑treatment did not alter their effect.
Conclusion: The investigated flavones exhibited promising antidepressant activity in both the animal models of depression. However, the flavone compounds did not alter the motor coordination and ambulatory behavior in the Rotarod and locomotor activity test. The participation of serotonergic, adrenergic, and opioid mechanism in the antidepressant activity of these compounds was elucidated from the results, and the role of NO pathway was excluded
Direct Urca neutrino rate in colour superconducting quark matter
If deconfined quark matter exists inside compact stars, the primary cooling
mechanism is neutrino radiation via the direct Urca processes d->u+e+antinu_e
and u+e->d+nu_e. Below a critical temperature, T_c, quark matter forms a colour
superconductor, one possible manifestation of which is a condensate of
quark Cooper pairs in an electric-charge neutralising background of electrons.
We compute the neutrino emission rate from such a phase, including charged
pair-breaking and recombination effects, and find that on a material
temperature domain below T_c the pairing-induced suppression of the neutrino
emission rate is not uniformly exponential. If gapless modes are present in the
condensed phase, the emissivity at low temperatures is moderately enhanced
above that of completely unpaired matter. The importance of charged current
pair-breaking processes for neutrino emission both in the fully gapped and
partially gapped regimes is emphasised.Comment: 5 pages, 2 figures; to appear in Phys. Rev. C (Rapid Comm.
Neutrino emission in neutron matter from magnetic moment interactions
Neutrino emission drives neutron star cooling for the first several hundreds
of years after its birth. Given the low energy ( keV) nature of this
process, one expects very few nonstandard particle physics contributions which
could affect this rate. Requiring that any new physics contributions involve
light degrees of freedom, one of the likely candidates which can affect the
cooling process would be a nonzero magnetic moment for the neutrino. To
illustrate, we compute the emission rate for neutrino pair bremsstrahlung in
neutron-neutron scattering through photon-neutrino magnetic moment coupling. We
also present analogous differential rates for neutrino scattering off nucleons
and electrons that determine neutrino opacities in supernovae. Employing
current upper bounds from collider experiments on the tau magnetic moment, we
find that the neutrino emission rate can exceed the rate through neutral
current electroweak interaction by a factor two, signalling the importance of
new particle physics input to a standard calculation of relevance to neutron
star cooling. However, astrophysical bounds on the neutrino magnetic moment
imply smaller effects.Comment: 9 pages, 1 figur
Influences of nano zero valent ion of kaolin and Fe2+ supported kaolin nanoparticles for metal ion separation thorough ultrafiltration
In this work, clay based nanocomposite material was synthesized by wet chemical route and nano zero valent ion of kaolin (nZVI:Kaolin) were prepared using sodium borohydride reduction method. The nZVI:Kaolin and Fe:Kaolin nanoparticles were characterized using XRD, FTIR and SEM and antimicrobial activity. The nZVI:Kaolin and Fe:Kaolin were incorporated into polyethersulfone (PES) membranes for metal ion separation through ultrafiltration. The influences of nZVI:Kaolin and Fe supported clay nanoparticles on PES membranes were characterized their modification in functional properties, hydrophilicity and morphological structure. The clean water flux was enhanced to PES membrane by addition of nZVI:Kaolin and Fe:Kaolin nanoparticles. The Cu (ii), Ni (ii) and Cd (ii) metal ions flux was increased for 0.15 wt% of nZVI and Fe:Kaolin nanoparticles in PES which is due to increase in hydrophilicity and change in morphological structure
- …