In the present paper we develop an algorithm for all spherically symmetric anisotropic charged fluid distributions. Considering a new source function
ν
(
r
)
we find a set of solutions which is ...physically well behaved and represents compact stellar models. A detailed study specifically shows that the models actually correspond to strange stars in terms of their mass and radius. In this connection we investigate several physical properties like energy conditions, stability, mass–radius ratio, electric charge content, anisotropic nature and surface redshift through graphical plots and mathematical calculations. All the features from these studies are in excellent agreement with the already available evidence in theory as well as observations.
We attempt to study a singularity-free model for the spherically symmetric anisotropic strange stars under Einstein’s general theory of relativity by exploiting the Tolman–Kuchowicz (Tolman in Phys ...Rev 55:364,
1939
; Kuchowicz in Acta Phys Pol 33:541,
1968
) metric. Further, we have assumed that the cosmological constant
Λ
is a scalar variable dependent on the spatial coordinate
r
. To describe the strange star candidates we have considered that they are made of strange quark matter distribution, which is assumed to be governed by the MIT bag equation of state. To obtain unknown constants of the stellar system we match the interior Tolman–Kuchowicz metric to the exterior modified Schwarzschild metric with the cosmological constant, at the surface of the system. Following Deb et al. (Ann Phys 387:239,
2017
) we have predicted the exact values of the radii for different strange star candidates based on the observed values of the masses of the stellar objects and the chosen parametric values of the
Λ
as well as the bag constant
B
. The set of solutions satisfies all the physical requirements to represent strange stars. Interestingly, our study reveals that as the values of the
Λ
and
B
increase the anisotropic system become gradually smaller in size turning the whole system into a more compact ultra-dense stellar object.
Generalised model for anisotropic compact stars Maurya, S. K.; Gupta, Y. K.; Ray, Saibal ...
European physical journal. C, Particles and fields,
12/2016, Volume:
76, Issue:
12
Journal Article
Peer reviewed
Open access
In the present investigation an exact generalised model for anisotropic compact stars of embedding class 1 is sought with a general relativistic background. The generic solutions are verified by ...exploring different physical aspects, viz. energy conditions, mass–radius relation, stability of the models, in connection to their validity. It is observed that the model presented here for compact stars is compatible with all these physical tests and thus physically acceptable as far as the compact star candidates
RXJ
1856-37,
SAX
J
1808.4-3658 (
SS
1) and
SAX
J
1808.4-3658 (
SS
2) are concerned.
In this article we obtain a new anisotropic solution for Einstein’s field equations of embedding class one metric. The solution represents realistic objects such as
Her X-1
and
RXJ 1856-37
. We ...perform a detailed investigation of both objects by solving numerically the Einstein field equations with anisotropic pressure. The physical features of the parameters depend on the anisotropic factor i.e. if the anisotropy is zero everywhere inside the star then the density and pressures will become zero and the metric turns out to be flat. We report our results and compare with the above mentioned two compact objects as regards a number of key aspects: the central density, the surface density onset and the critical scaling behaviour, the effective mass and radius ratio, the anisotropization with isotropic initial conditions, adiabatic index and red shift. Along with this we have also made a comparison between the classical limit and theoretical model treatment of the compact objects. Finally we discuss the implications of our findings for the stability condition in a relativistic compact star.
Anisotropic models for compact stars Maurya, S. K.; Gupta, Y. K.; Ray, Saibal ...
The European physical journal. C, Particles and fields,
05/2015, Volume:
75, Issue:
5
Journal Article
Peer reviewed
Open access
In the present paper we obtain an anisotropic analog of the Durgapal and Fuloria (Gen Relativ Gravit 17:671,
1985
) perfect fluid solution. The methodology consists of contraction of the anisotropic ...factor
Δ
with the help of both metric potentials
e
ν
and
e
λ
. Here we consider
e
λ
the same as Durgapal and Fuloria (Gen Relativ Gravit 17:671,
1985
) did, whereas
e
ν
is as given by Lake (Phys Rev D 67:104015,
2003
). The field equations are solved by the change of dependent variable method. The solutions set mathematically thus obtained are compared with the physical properties of some of the compact stars, strange star as well as white dwarf. It is observed that all the expected physical features are available related to the stellar fluid distribution, which clearly indicates the validity of the model.
Spherically symmetric charged compact stars Maurya, S. K.; Gupta, Y. K.; Ray, Saibal ...
European physical journal. C, Particles and fields,
08/2015, Volume:
75, Issue:
8
Journal Article
Peer reviewed
Open access
In this article we consider the static spherically symmetric metric of embedding class 1. When solving the Einstein–Maxwell field equations we take into account the presence of ordinary baryonic ...matter together with the electric charge. Specific new charged stellar models are obtained where the solutions are entirely dependent on the electromagnetic field, such that the physical parameters, like density, pressure etc. do vanish for the vanishing charge. We systematically analyze altogether the three sets of Solutions I, II, and III of the stellar models for a suitable functional relation of
ν
(
r
)
. However, it is observed that only the Solution I provides a physically valid and well-behaved situation, whereas the Solutions II and III are not well behaved and hence not included in the study. Thereafter it is exclusively shown that the Solution I can pass through several standard physical tests performed by us. To validate the solution set presented here a comparison has also been made with that of the compact stars, like
R
X
J
1856
-
37
,
H
e
r
X
-
1
,
P
S
R
1937
+
21
,
P
S
R
J
1614
-
2230
, and
P
S
R
J
0348
+
0432
, and we have shown the feasibility of the models.
In the present study we search for a new stellar model with spherically symmetric matter and a charged distribution in a general relativistic framework. The model represents a compact star of ...embedding class 1. The solutions obtained here are general in nature, having the following two features: first of all, the metric becomes flat and also the expressions for the pressure, energy density, and electric charge become zero in all the cases if we consider the constant
A
=
0
, which shows that our solutions represent the so-called ‘electromagnetic mass model’
17
, and, secondly, the metric function
ν
(
r
)
, for the limit
n
tending to infinity, converts to
ν
(
r
)
=
C
r
2
+
l
n
B
, which is the same as considered by Maurya et al.
11
. We have investigated several physical aspects of the model and find that all the features are acceptable within the requirements of contemporary theoretical studies and observational evidence.
Abstract The use of novel active ingredients for the functional modification of chitosan nanoformulations has attracted global attention. In this study, chitosan has been functionalized via histidine ...to craft novel chitosan–histidine nanoformulation (C–H NF) using ionic gelation method. C–H NF exhibited elite physico-biochemical properties, influencing physiological and biochemical dynamics in Tomato. These elite properties include homogenous-sized nanoparticles (314.4 nm), lower PDI (0.218), viscosity (1.43 Cps), higher zeta potential (11.2 mV), nanoparticle concentration/ml (3.53 × 10 8 ), conductivity (0.046 mS/cm), encapsulation efficiency (53%), loading capacity (24%) and yield (32.17%). FTIR spectroscopy revealed histidine interaction with C–H NF, while SEM and TEM exposed its porous structure. Application of C–H NF to Tomato seedling and potted plants through seed treatment and foliar spray positively impacts growth parameters, antioxidant-defense enzyme activities, reactive oxygen species (ROS) content, and chlorophyll and nitrogen content. We claim that the histidine-functionalized chitosan nanoformulation enhances physico-biochemical properties, highlighting its potential to elevate biochemical and physiological processes of Tomato plant.
Drug discovery and development is an expensive, time-consuming, and
risky enterprise. In order to accelerate the drug development process
with reduced risk of failure and relatively lower costs, ...pharmaceutical
companies have adopted drug repositioning as an alternative. This
strategy involves exploration of drugs that have already been approved
for treatment of other diseases and/or whose targets have already been
discovered. Various techniques including data mining, bioinformatics,
and usage of novel screening platforms have been used for
identification and screening of potential repositioning candidates.
However, challenges in clinical trials and intellectual property issues
may be encountered during the repositioning process. Nevertheless, such
initiatives not only add value to the portfolio of pharmaceutical
companies but also provide an opportunity for academia and government
laboratories to develop new and innovative uses of existing drugs for
infectious and neglected diseases, especially in emerging countries
like India.
.
In the present article, we have constructed static anisotropic compact star models of Einstein field equations for the spherical symmetric metric of embedding class one. By assuming the particular ...form of the metric function
ν
, we have solved the Einstein field equations for anisotropic matter distribution. The anisotropic models represent the realistic compact objects such as SAX J 1808.4-3658 (SS1), Her X-1, Vela X-12, PSR J1614-2230 and Cen X-3. We have reported our results in details for the compact star Her X-1 on the ground of physical properties such as pressure, density, velocity of sound, energy conditions, TOV equation and red-shift etc. Along with these, we have also discussed about the stability of the compact star models. Finally we made a comparison between our anisotropic stars with the realistic objects on the key aspects as central density, central pressure, compactness and surface red-shift.
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