Magnetic nanoparticles-supported tungstosilicic acid: as an efficient magnetically separable solid acid for the synthesis of benzoazoles in water

The magnetic nanoparticles-supported tungstosilicic acid (TSAMNP) was found to be a highly efficient solid acid for the synthesis of benzoazoles in water. TSAMNP catalyst was achieved by the immobilization of tungstosilicic acid [H₄(W₁₂SiO₄₀)] species on the silica core–shell magnetic nanoparticles (Fe₃O₄@SiO₂). A variety of aldehydes were successfully condensed with 1,2-diaminobenzene, 2-aminophenol and 2-aminothiophenol in water as a green solvent to synthesize benzoazoles in good-to-excellent yields. TSAMNP catalyst was easily separated from the reaction mixture and reused several times without any loss of efficiency.     

Coherence and oscillations of cosmic neutrinos

For cosmic neutrinos we study the conditions and the effects of the coherence loss as well as coherent broadening of the spectrum. We evaluate the width of the neutrino wavepacket produced by charged particles under various circumstances: in an interaction-free environment, in a radiation-dominated medium (typical of the sources of the gamma ray bursts) and in the presence of a magnetic field. The effect of the magnetic field on the wavepacket size appears to be more important than the scattering. If the magnetic field at the source is larger than 10 Gauss, the coherence of neutrinos will be lost while traveling over cosmological distances. Various applications of these results have been considered. We find that for large magnetic fields (B>10⁹ Gauss) and high energies (E_ν>PeV), “coherent broadening” can modify the energy spectrum of neutrinos. In the coherent case, averaging out the oscillatory terms of the probabilities does not induce any statistical uncertainty beyond what expected in the absence of these terms. A deviation from the standard quantum mechanics that preserves average energy and unitarity cannot alter the picture.     

R parity violation assisted thermal leptogenesis in the seesaw mechanism

Successful leptogenesis within the simplest type I supersymmetric seesaw mechanism requires the lightest of the three right-handed neutrino supermultiplets to be heavier than approximately 10(9) GeV. Thermal production of such (s)neutrinos requires very high reheating temperatures which result in an overproduction of gravitinos with catastrophic consequences for the evolution of the Universe. In this Letter, we let R parity be violated through a lambda(i)N(i)H(u)H(d) term in the superpotential, where N(i) are right-handed neutrino supermultiplets. We show that in the presence of this term, the produced lepton-antilepton asymmetry can be enhanced. As a result, even for N1 masses as low as 10(6) GeV or less, we can obtain the observed baryon asymmetry of the Universe without gravitino overproduction.     

Nonlinear eccentric low-velocity impact analysis of a highly prestressed FGM rectangular plate, using a refined contact law

In the present paper, a nonlinear analysis is presented for response prediction of a low-velocity eccentric impact between a functionally graded rectangular plate and a rigid sphere or a projectile with a spherical nose. Some of the novelties of the present paper are (i) considering the more general case of eccentric impact, (ii) investigating effects of the initial in-plane loads on the impact responses of the functionally graded plates, especially for compressive loads that are comparable but not equal to the buckling loads, (iii) using a contact law that incorporates influences of the transverse variations of the material properties of the substrate layers and the plate thickness, and (iv) using nonlinear strain-displacement relations instead of using the traditional infinitesimal deformations assumption for assessment of influences of the initial preloads. Due to using von Karman strain-displacement relations and a nonlinear contact law, the governing equations are highly nonlinear. For this reason, an iterative solution scheme is employed. A sensitivity analysis is performed to investigate influences of the specifications of the plate and the indenter, the eccentric value, and the in-plane preloads on the indentation and force time histories. Results reveal that due to the resulting increase in the contact force, slightly higher damages may be expected for impacted FGM plates subjected to initial compressive in-plane loads.     

Microfluidics for Porous Systems: Fabrication,Microscopy and Applications

Transport in Porous Media - No matter how sophisticated the structures are and on what length scale the pore sizes are, fluid displacement in porous media can be visualized, captured, mimicked and...     

Analysis of chemically reactive species with mixed convection and Darcy–Forchheimer flow under activation energy: a novel application for geothermal reservoirs

Journal of Thermal Analysis and Calorimetry - In the present article, an analysis has been performed to discuss the impact of steady mixed convection with Darcy–Forchheimer flow towards...     

Self‐Assembled Multimetallic/Peptide Complexes: Structures and Unimolecular Reactions of [Mn(GlyGly−H)2n−1]+ and Mn+1(GlyGly−H2n]2+ Clusters in the Gas Phase

The unimolecular chemistry and structures of self‐assembled complexes containing multiple alkaline‐earth‐metal dications and deprotonated GlyGly ligands are investigated. Singly and doubly charged ions [M_n(GlyGly?H)_n‐1]⁺ (n=2–4), [M_n+1(GlyGly?H)_2n]²⁺ (n=2,4,6), and [M(GlyGly?H)GlyGly]⁺ were observed. The losses of 132 Da (GlyGly) and 57 Da (determined to be aminoketene) were the major dissociation pathways for singly charged ions. Doubly charged Mg²⁺ clusters mainly lost GlyGly, whereas those containing Ca²⁺ or Sr²⁺ also underwent charge separation. Except for charge separation, no loss of metal cations was observed. Infrared multiple photon dissociation spectra were the most consistent with the computed IR spectra for the lowest energy structures, in which deprotonation occurs at the carboxyl acid groups and all amide and carboxylate oxygen atoms are complexed to the metal cations. The N?H stretch band, observed at 3350 cm^?1, is indicative of hydrogen bonding between the amine nitrogen atoms and the amide hydrogen atom. This study represents the first into large self‐assembled multimetallic complexes bound by peptide ligands.     

On the location of flame edge in Shadowgraph pictures of spherical flames: a theoretical and experimental study

In this paper, a theoretical model based on geometrical optics has been developed to analyze the light intensity pattern of Shadowgraph pictures of spherical flames. The theoretical results have been compared with experimental measurement of light intensity profiles across the flame front using commercially available image processing software. These results are in good agreement. The theory predicts that the sudden change of light intensity from dark to bright does not coincide with the flame edge unless the flame thickness is negligible. Experimental results agree very well with the theoretical predictions.