Bu-Ali Sina University

About: Bu-Ali Sina University is a education organization based out in Hamadan, Hamadān, Iran. It is known for research contribution in the topics: Catalysis & Adsorption. The organization has 4078 authors who have published 7969 publications receiving 122828 citations.

Fabrication, characterization and application of GO/Fe3O4/Pd nanocomposite as a magnetically separable and reusable catalyst for the reduction of organic dyes

Abstract: In this work, GO/Fe 3 O 4 /Pd nanocomposite has been prepared via a simple method and its catalytic activity has been tested for the reduction of 4-nitrophenol (4-NP), Methyl Orange (MO), Methylene blue (MB) and Congo red (CR) in the presence of NaBH 4 in aqueous medium at room temperature. X-ray diffraction (XRD), Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the morphology and composition of GO/Fe 3 O 4 /Pd nanocomposite. Furthermore, the catalyst can be recovered and recycled several times without significant losing of its activity in reduction process.

Absence of a fundamental acceleration scale in galaxies

Abstract: Dark matter is currently one of the main mysteries of the Universe. There is much strong indirect evidence that supports its existence, but there is yet no sign of a direct detection1–3. Moreover, at the scale of galaxies, there is tension between the theoretically expected dark matter distribution and its indirectly observed distribution4–7. Therefore, phenomena associated with dark matter have a chance of serving as a window towards new physics. The radial acceleration relation8,9 confirms that a non-trivial acceleration scale a0 can be found from the internal dynamics of several galaxies. The existence of such a scale is not obvious as far as the standard cosmological model is concerned10,11, and it has been interpreted as a possible sign of modified gravity12,13. Here, we consider 193 high-quality disk galaxies and, using Bayesian inference, show that the probability of existence of a fundamental acceleration is essentially 0: the null hypothesis is rejected at more than 10σ. We conclude that a0 is of emergent nature. In particular, the modified Newtonian dynamics theory14–17—a well-known alternative to dark matter based on the existence of a fundamental acceleration scale—or any other theory that behaves like it at galactic scales, is ruled out as a fundamental theory for galaxies at more than 10σ. By studying the properties of almost 200 disk galaxies, it is shown that modified Newtonian dynamics (MOND), or MOND-like alternative theories of gravity based on the existence of a fundamental acceleration scale, are ruled out as fundamental theories for galaxies at more than 10σ.