Search results for "DF"
showing 10 items of 1699 documents
Mpro-SARS-CoV-2 Inhibitors and Various Chemical Reactivity of 1-Bromo- and 1-Chloro-4-vinylbenzene in [3 + 2] Cycloaddition Reactions
2021
The regioselectvity and the mechanism of the (32CA) cycloadditions reactions of 1-bromo-4-vinylbenzene 1 and 1-chloro-4-vinylbenzene 2 with benzonitrile oxide 3 were investigated under the molecular electron density theory (MEDT) at the B3LYP/6-311++G(d,p) computational level. Evaluation of the ELF reveals that these zwitterionic type (zw-type) 32CA reactions take place in a two-stage one-step mechanism. This MEDT study shows that the meta isoxazolines are kinetically and thermodynamically favored over the ortho ones, these 32CA reactions being completely regioselective, in agreement with experimental outcomes. In addition, the efficiency of isoxazolines against SARS-CoV-2 have been also in…
The richest superclusters : I Morphology
2007
We study the morphology of the richest superclusters from the catalogues of superclusters of galaxies in the 2dF Galaxy Redshift Survey and compare the morphology of real superclusters with model superclusters in the Millennium Simulation. We use Minkowski functionals and shapefinders to quantify the morphology of superclusters: their sizes, shapes, and clumpiness. We generate empirical models of simple geometry to understand which morphologies correspond to the supercluster shapefinders. We show that rich superclusters have elongated, filamentary shapes with high-density clumps in their core regions. The clumpiness of superclusters is determined using the fourth Minkowski functional $V_3$.…
Multi-scale morphology of the galaxy distribution
2006
Many statistical methods have been proposed in the last years for analyzing the spatial distribution of galaxies. Very few of them, however, can handle properly the border effects of complex observational sample volumes. In this paper, we first show how to calculate the Minkowski Functionals (MF) taking into account these border effects. Then we present a multiscale extension of the MF which gives us more information about how the galaxies are spatially distributed. A range of examples using Gaussian random fields illustrate the results. Finally we have applied the Multiscale Minkowski Functionals (MMF) to the 2dF Galaxy Redshift Survey data. The MMF clearly indicates an evolution of morpho…
Sistemi informativi 3D per i BB.CC. e l'archeologia: il Castello di Maredolce a Palermo
2014
Il mondo della ricerca nel campo dei BB.CC. sta guardando con sempre maggior interesse all’uso di tecnologie informatiche integrate, che consentano di fornire e condividere in rete dati quantitativi e qualitativi, geometrici, posizionali, alfanumerici, relativi ai BB.CC., sfruttando l’interazione tra banche dati e modelli 3D. Tali modelli, dunque, oltre a fornire una ricostruzione virtuale del monumento con la possibilità di navigare ed analizzare l’oggetto in dettaglio, costituiscono lo strumento per accedere ad informazioni eterogenee (testi, immagini, sequenze video, ecc.) sui manufatti, raccolte ed organizzate in database relazionali interrogabili, al fine di una piena comprensione e co…
A Universal Length-Dependent Vibrational Mode in Graphene Nanoribbons
2019
Graphene nanoribbons (GNRs) have attracted considerable interest as their atomically tunable structure makes them promising candidates for future electronic devices. However, obtaining detailed information about the length of GNRs has been challenging and typically relies on low-temperature scanning tunneling microscopy. Such methods are ill-suited for practical device application and characterization. In contrast, Raman spectroscopy is a sensitive method for the characterization of GNRs, in particular for investigating their width and structure. Here, we report on a length-dependent, Raman active low-energy vibrational mode that is present in atomically precise, bottom-up synthesized armch…
Exploration of the Activation Mechanism of the Epigenetic Regulator MLL3: A QM/MM Study
2021
The mixed lineage leukemia 3 or MLL3 is the enzyme in charge of the writing of an epigenetic mark through the methylation of lysine 4 from the N-terminal domain of histone 3 and its deregulation has been related to several cancer lines. An interesting feature of this enzyme comes from its regulation mechanism, which involves its binding to an activating dimer before it can be catalytically functional. Once the trimer is formed, the reaction mechanism proceeds through the deprotonation of the lysine followed by the methyl-transfer reaction. Here we present a detailed exploration of the activation mechanism through a QM/MM approach focusing on both steps of the reaction, aiming to provide new…
Hydrogenolysis of hydroxymatairesinol on Y derived catalysts: a computational study
2010
Hydrogenolysis of 7-hydroxymatairesinol (HMR) to matairesinol (MAT) occurs on palladium supported acidic catalysts. HMR has three stereochemical centres and naturally exists as a mixture of two diastereoisomers, namely RRR-HMR and SRR-HMR. The latter is significantly more reactive than the former, in the reaction above. In order to elucidate the hydrogenolysis mechanism, simple surface events involving HMR derivatives on aluminated faujasite (H-Y) fragments were simulated by quantum chemical calculations. The metallic function of a Pd/H-Y acidic catalyst was also mimicked by a minimal palladium cluster. Stereochemical evidences pointed already out that water β-elimination on the epimeric ce…
Plant-animal interactions in fire-prone ecosystems
2018
SÍNTESIS Estudiar cómo responden las interacciones ecológicas a las perturbaciones es clave para abordar la creciente pérdida de biodiversidad en diferentes ecosistemas. En la Tierra existen especies que han evolucionado ante la presencia recurrente de perturbaciones naturales, como ocurre en ecosistemas con incendios frecuentes. En ellos el fuego se originó poco después de la aparición de las primeras plantas terrestres y también algunos de los patrones de incendios característicos que todavía permanecen. Sin embargo, las actividades humanas están alterando los patrones naturales de incendios, lo que puede suponer una amenaza incluso para las especies que presentan una rápida recuperación …
Lightning-ignited wildfires and long continuing current lightning in the Mediterranean Basin: Preferential meteorological conditions
2021
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
2019
Documento escrito por un elevado número de autores/as, sólo se referencia el/la que aparece en primer lugar y los/as autores/as pertenecientes a la UC3M For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D–T mixtures since 1997 and the first ever D–T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D–T campaign (DTE2). This paper addresses the key elements developed by the JET programme d…