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Jakarta, Indonesia

Sadeghian S.,Institute for Research in Fundamental Sciences | Sadeghian S.,Azzahra University | Sheikh-Jabbari M.M.,Institute for Research in Fundamental Sciences | Vahidinia M.H.,Institute for Research in Fundamental Sciences | Yavartanoo H.,CAS Institute of Theoretical Physics
Nuclear Physics B | Year: 2015

We study the near horizon structure of Extremal Vanishing Horizon (EVH) black holes, extremal black holes with vanishing horizon area with a vanishing one-cycle on the horizon. We construct the most general near horizon EVH and near-EVH ansatz for the metric and other fields, like dilaton and gauge fields which may be present in the theory. We prove that (1) the near horizon EVH geometry for generic gravity theory in generic dimension has a three dimensional maximally symmetric subspace; (2) if the matter fields of the theory satisfy strong energy condition either this 3d part is AdS3, or the solution is a direct product of a locally 3d flat space and a d-3 dimensional part; (3) these results extend to the near horizon geometry of near-EVH black holes, for which the AdS3 part is replaced with BTZ geometry. We present some specific near horizon EVH geometries in 3, 4 and 5 dimensions for which there is a classification. We also briefly discuss implications of these generic results for generic (gauged) supergravity theories and also for the thermodynamics of near-EVH black holes and the EVH/CFT proposal. © 2015. Source


Sulfonic acid-functionalized silica-coated nano-Fe3O4 particles (Fe3O4@SiO2-SO3H) have been prepared as a novel heterogeneous acid using a facile process. The material was subsequently identified as an efficient catalyst for the synthesis of a variety of tetraketone derivatives via the Knoevenagel condensation and Michael addition reactions of aromatic aldehydes to dimedone, 1,3-indanedione, and 1,3-dimethyl barbituric acid. The catalyst could be readily recovered using a simple external magnet and reused several times without any significant loss in activity. The current catalytic process is both sustainable and economical because it operates under aqueous conditions, the catalyst can be recovered and reused, and the reactions themselves require only a short time and provide the products in high yield. Source


Heravi M.M.,Azzahra University | Tavakoli-Hoseini N.,Islamic Azad University at Mashhad | Bamoharram F.F.,Islamic Azad University at Mashhad
Synthetic Communications | Year: 2011

A simple, clean, and environmentally benign three-component process for the synthesis of amidoalkyl naphthols using Brnsted acidic ionic liquids as efficient catalysts in solution and under solvent-free conditions is described. Copyright © Taylor & Francis Group, LLC. Source


Davoodnia A.,Islamic Azad University at Mashhad | Heravi M.M.,Azzahra University | Safavi-Rad Z.,Islamic Azad University at Mashhad | Tavakoli-Hoseini N.,Islamic Azad University at Mashhad
Synthetic Communications | Year: 2010

3-Methyl-1-(4-sulfonic acid)butylimidazolium hydrogen sulfate [(CH 2)4SO3HMIM][HSO4], a Brnsted acidic ionic liquid, has been used as an efficient, green, and reusable catalyst for the synthesis of 1,2,4,5-tetrasubstituted imidazoles using benzil, an aromatic aldehyde, and a primary amine in the presence of ammonium acetate under solvent-free conditions. The catalyst could be recycled and reused several times without noticeably decreasing the catalytic activity. © Taylor & Francis Group, LLC. Source


Javid A.,Islamic Azad University at Mashhad | Heravi M.M.,Azzahra University | Bamoharram F.F.,Islamic Azad University at Mashhad
E-Journal of Chemistry | Year: 2011

A highly efficient one-pot synthesis of 1,8-dioxo-octahydroxanthenes from dimedone and various aromatic aldehydes under reflux conditions in water, catalyzed by silica-supported preyssler nano particles (SPNP) is reported. The products were formed in excellent yields and the acidic catalyst was completely heterogeneous and can be recycled for many times. © Copyright E-Journal of Chemistry 2004-2011. Source

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