309 research outputs found
Anisotropic strange stars in Tolman-Kuchowicz spacetime
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 metric. Further, we have assumed that the
cosmological constant is a scalar variable dependent on the spatial
coordinate . To describe the strange star candidates we have considered that
they are made of strange quark matter (SQM) 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. 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
as well as the bag constant . The set of solutions
satisfies all the physical requirements to represent strange stars.
Interestingly, our study reveals that as the values of the and
increase the anisotropic system becomes gradually smaller in size
turning the whole system into a more compact ultra-dense stellar object.Comment: 18 pages, 10 figure
A Comparative Efficiency Study of Two Adsorbent Materials to Remove Eosin Y Dye from Aqueous Solutions
This study was done to find a cheap, available and ecofriendly materials that can remove eosin y dye from aqueous solutions by adsorption in this study, two adsorbent materials were used, the shells of fresh water clam (Cabicula fluminea) and walnut shells. To make a comparison between the two adsorbents, five experiments were conducted. First, the effects of the contact time, here the nut shell removed the dye quickly, while the C. flumina need more contact time to remove the dye. Second, the effects of adsorbent weight were examined. The nut shell was very promising and for all used adsorbent weight, the R% ranged from 94.87 to 99.29. However C. fluminea was less effective in removing the dye with R% ranged from 47.59 to 55.39. The third experiment was initial dye concentration. The C. fluminea showed very low ability to remove eosin y , while the nut shell was more effective in removing the dye with R% up to 97.36 and an inverse correlation between the increase of initial dye concentration and R%. The fourth experiment was the effect of pH value of the solution and the adsorbent particles size. The results show that fine particles were more effective than granular particles. Throughout the whole study, the walnut shell was very promising in removing the dye, while the C. fluminea shell was much less effective than the walnut shell
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