1,721,238 research outputs found
Oxidation of N-Methyl-9-t-butylacridane by Iodosylbenzene Catalyzed by Tetrakis(pentafluorophenyl) Porphyrin Iron(III). A Tool to Investigate the Mechanism of the Biomimetic N-Demethylation of Aromatic Tertiary Amines.
No full textThe PhIO promoted oxidation of N-methyl-9-t-butylacridane (1) catalyzed by tetrakis(pentafluorophenyl) porphyrin iron(III) leads first to 9-t-butylacridane and then to acridine. It is suggested that 1 can represent a reliable machanistic probe to detect the intervention of radical cations in the oxidation of aromatic amines. (C) 1999 Elsevier Science Ltd. All rights reserved
Cross-correlation between cosmological and astrophysical datasets: the Planck and Herschel case
No full textWe present the first measurement of the correlation between the map of the CMB lensing potential derived from the Planck nominal mission data and z% 1.5 galaxies detected by Herschel-ATLAS (H-ATLAS) survey covering about 550 deg2. We detect the cross-power spectrum with a significance of ∼ 8.5σ, ruling out the absence of correlation at 9σ. We check detection with a number of null tests. The amplitude of cross-correlation and the galaxy bias are estimated using joint analysis of the cross-power spectrum and the galaxy survey auto-spectrum, which allows to break degeneracy between these parameters. The estimated galaxy bias is consistent with previous estimates of the bias for the H-ATLAS data, while the cross-correlation amplitude is higher than expected for a ΛCDM model. The content of this work is to appear in a forthcoming pape
Synthesis of Sulfoxides by the Hydrogen Peroxide Induced Oxidation of Sulfides Catalyzed by Iron Tetrakis(pentafluorophenyl)porphyrin:Scope and Chemoselectivity
No full textThe oxidation of sulfides with H2O2 catalyzed by iron tetrakis(pentafluorophenyl)porphyrin in EtOH is an efficient and chemoselective process. With a catalyst concentration 0.03-0.09% of that of the substrate, sulfoxides are obtained with yields generally around 90-95% of isolated product. With vinyl and allyl sulfides, no epoxidation is observed. With a catalyst concentration between 0.09% and 0.25% of that of the substrate, sulfones are obtained in almost quantitative yield and with the same high chemoselectivity observed in the synthesis of sulfoxides
Structure and History of Dark Matter Halos in Galaxies and Galaxy Systems
No full textWe investigate the structure and history of Dark Matter (DM) halos in galaxies and galaxy systems. Our theoretical framework is provided by the two-stage cosmogonical development of DM halos, and by the related “α-profiles”. The latter solve the Jeans equation for the self-gravitating DM equilibria, and yield the radial runs of the density ρ(r) and the velocity dispersion σr2(r) in terms of the DM “entropy” K≡σr2/ρ2/3∝rα highlighted by recent N-body simulations to have a uniform slope α within the halo “body”. The former constrains the entropy slope α to a value within the narrow range 1.25–1.3; such a value applies in the halo body since the transition time that, both in our semianalytic description and in state-of-the-art numerical simulations, is found to separate two stages in the development of a DM halo: an early fast collapse including a few violent major mergers building up the halo body by dynamical relaxation; and a later, quasi-equilibrium stage during which the body is almost unaffected while the outskirts develop from the inside-out by minor mergers and smooth accretion. These physically based α-profiles meet the overall requirements from gravitational lensing observations, being intrinsically flatter at the center and steeper in the outskirts relative to the empirical NFW formula. In quantitative detail, we test them with the recent extensive dataset from weak and strong lensing observations in and around the cluster A1689. We find an optimal fit at both small and large scales in terms of a halo constituted by an early body with α≈1.25 and by recent extended outskirts making up a concentration parameter c≈10; we consistently interpret the latter value in terms of the variance expected in the two-stage halo development under the standard ΛCDM cosmology
Semi-empirical models of galaxy formation and evolution
No full textWe provide a review on semi-empirical models of galaxy formation and evolution. We present a brief census of the three main modeling approaches to galaxy evolution, namely hydrodynamical simulations, semi-analytic models, and semi-empirical models (SEMs). We focus on SEMs in their different flavors, i.e. interpretative, descriptive and hybrid, discussing the peculiarities and highlighting virtues and shortcomings for each of these variants. We dissect a simple and recent hybrid SEM from our team to highlight some technical aspects. We offer some outlook on the prospective developments of SEMs. Finally, we provide a short summary of this review
Oxygenation of benzyldimethylamine by singlet oxygen. Products and mechanism
No full textA product study of the reaction of benzyldimethylamine (1) with thermally and photochemically generated (1)O(2) in MeCN was carried out. Benzaldehyde and N-benzyl-N-methylformamide are the reaction products, oxygenation representing ca. 9% of the overall quenching of (1)O(2) by 1. The temperature effect and the intermolecular and intramolecular kinetic deuterium isotope effects were also determined. It is suggested that the products derive from an intracomplex hydrogen atom transfer in a reversibly formed charge-transfer complex
Guanine Oxidation in Double Stranded DNA by MnTMPyP/KHSO5: at Least Three independent Reaction Pathways.
No full textIn order to better define the mechanism and the products of guanine oxidation within DNA, we investigated the details of the mechanism of guanine oxidation by a metalloporphyrin, Mn-TMPyP, associated to KHSO(5) on oligonucleotides. We found that the three major products of guanine oxidation are formed by independent reaction routes. The oxidized guanidinohydantoin (1) and the proposed spiro compound 3 derivatives are not precursors of imidazolone lesion (Iz). These guanine lesions as well as their degradation products, may account for non-detected guanine oxidation products on oxidatively damaged DNA
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