5,698 research outputs found
Fracture toughness testing data: A technology survey and bibliography
Announced survey includes reports covering fracture toughness testing for various structural materials including information on plane strain and developing areas of mixed mode and plane strain test conditions. Bibliography references cite work and conclusions in fracture toughness testing and application of fracture toughness test data, and in fracture mechanics analysis
Life prediction of materials exposed to monotonic and cyclic loading: A technology survey and bibliography
Announced survey directs attention toward low cycle fatigue and thermal fatigue experienced at elevated temperatures equivalent to those found in hot end of gas turbine engine. Majority of bibliographic references are on life prediction for materials exposed to monotonic and cyclic loading in high temperature environments
MECHANISTIC STUDY OF A RUTHENIUM HYDRIDE COMPLEX OF TYPE [RuH(CO)(N-N)(PR3)2]+ AS CATALYST PRECURSOR FOR THE HYDROFORMYLATION REACTION OF 1-HEXENE
Indexación: Web of Science; Scopus; Scielo.The catalytic activity of systems of type [RuH(CO)(N-N)(PR3)(2)](+) was evaluated in the hydroformylation reaction of 1-hexene. The observed activity is explained through a reaction mechanism on the basis of the quantum theory. The mechanism included total energy calculations for each of the intermediaries of the elemental steps considered in the catalytic cycle. The deactivation of the catalyst precursors takes place via dissociation of the polypyridine ligand and the subsequent formation of thermodynamically stable species, such as RuH(CO)(3)(PPh3)(2) and RuH3(CO)(PPh3)(2), which interrupt the catalytic cycle. In addition, the theoretical study allows to explain the observed regioselectivity which is defined in two steps: (a) the hydride migration reaction with an anti-Markovnikov orientation to produce the alkyl-linear-complex (3.1a), which is more stable by 19.4 kJ/mol than the Markovnikov orientation (alkyl-branched-complex) (3.1b); (b) the carbon monoxide insertion step generates the carbonyl alkyl-linear specie (4.1a) which is more stable by 9.5 kJ/mol than the alternative species (4.1b), determining the preferred formation of heptanal in the hydroformylation of 1-hexene.
Palabras clavehttp://ref.scielo.org/db4yc
Las luces de la pobreza. Franciscanos y reforma en la Universidad de Córdoba del Tucumán
El siglo XVIII fue un tiempo de reformas administrativas y educativas en la Universidad de Córdoba del Tucumán, producto del plan de la nueva dinastía que ocupó el trono de España. Luego de la expulsión de los jesuitas (sus primitivos administradores) y la toma de posesión de la corporación por los franciscanos (fervientes adherentes al proyecto monárquico) los cambios se aceleraron. El trabajo parte de la hipótesis de que el acompañamiento de la reforma borbónica fue posible gracias a la renovación interna de la disciplina eclesial que experimentó la Orden en el siglo XVIII. Se estudia el pensamiento de los reformadores educativos seráficos y cómo sus ideas se plasmaron en el nuevo currículum de la universidad cordobesa.The eighteenth century was a time of administrative and educational reforms in the University of Córdoba of the Tucumán, which were the result of the plan followed by the new dynasty coming to the throne of Spain. After the Jesuits, its former administrators, were expelled, and once the Franciscans had taken charge of the corporation, the changes were speeded up because of their passionate support to the monarchical project. This article starts from the hypothesis that this support to the monarchical reform was possible thanks to the revival of ecclesiastical discipline within the Order itself in the eighteenth century. The seraphic educational reformers thought is herein studied as well as how their ideas were expressed in the new curriculum of the University of Córdoba of the Tucumán
Synthesis, reactivity studies, and cytotoxicity of two trans-Iodidoplatinum(II) complexes. Does photoactivation work?
trans-Platinum complexes have been the landmark in unconventional drugs prompting the development of innovative structures that might exhibit chemical and biological profiles different to cisplatin. Iodido complexes signaled a new turning point in the platinum drug design field when their cytotoxicity was reevaluated and reported. In this new study, we have synthesized and evaluated diodidoplatinum complexes trans-[PtI2(amine)(pyridine)] bearing aliphatic amines (isopropylamine and methylamine) and pyridines in trans configuration. X-ray diffraction data support the structural characterization. Their cytotoxicity has been evaluated in tumor cell lines such as SAOS-2, A375, T-47D, and HCT116. Moreover, we report their solution behavior and reactivity with biological models. Ultraviolet-a (UVA) irradiation induces an increase in their reactivity towards model nucleobase 5′-GMP in early stages, and promotes the release of the pyridine ligand (spectator ligand) at longer reaction times. Density Functional calculations have been performed and the results are compared with our previous studies with other iodido derivatives.MINECO CTQ-2015-68779
Estudio de los indicadores medioambientales atmosféricos y sus implicaciones en la salud pública en la comunidad autónoma de las Islas Baleares
La política tanto de la Unión Europea como de la Organización Mundial de la Salud en materia de Salud Ambiental basa sus directrices en la prevención de las enfermedades y en la creación de entornos saludables, tomando como referencia los riesgos y efectos sobre la salud humana, estableciendo distintos indicadores con el fin de corregir los niveles de contaminación. Estos factores representan, el medio que habitamos, donde trabajamos, los cambios naturales o artificiales que ese lugar manifiesta y la contaminación producida por el mismo ser humano a ese medio. Con el objetivo de reducir ese impacto, hemos estudiado las distintos tipos de enfermedades causadas por el impacto medioambiental en las Islas BalearesThe policies are analyzed both of the European Union and of the World Health Organization by the aim to establish indicators for correction levels of pollution. Environmental Health bases its guidelines on preventing disease and creating health-supportive environments. It concerned with the risks and effects on human health represent the means living and where you work, natural or artificial changes to the site represents and pollution caused by human beings themselves to that medium. In order to reduce this impact, we have studied the different kind of diseases caused by environmental impact in the Balearic Island
Recovering coherence from decoherence: a method of quantum state reconstruction
We present a feasible scheme for reconstructing the quantum state of a field
prepared inside a lossy cavity. Quantum coherences are normally destroyed by
dissipation, but we show that at zero temperature we are able to retrieve
enough information about the initial state, making possible to recover its
Wigner function as well as other quasiprobabilities. We provide a numerical
simulation of a Schroedinger cat state reconstruction.Comment: 8 pages, in RevTeX, 4 figures, accepted for publication in Phys. Rev.
A (november 1999
Landau Theory of Barocaloric Plastic Crystals
We present a simple Landau phenomenology for plastic-to-crystal phase
transitions and use the resulting model to calculate barocaloric effects in
plastic crystals that are driven by hydrostatic pressure. The essential
ingredients of the model are (i) a multipole-moment order parameter that
describes the orientational ordering of the constituent molecules, (ii)
coupling between such order parameter and elastic strains, and (iii) the
thermal expansion of the solid. The model captures main features of
plastic-to-crystal phase transitions, namely large volume and entropy changes
at the transition, and strong dependence of the transition temperature with
pressure. Using solid C under GPa as case example, we show that
calculated peak isothermal entropy changes of and peak adiabatic entropy changes of agree well
with experimental values.Comment: 17 pages, 3 figure
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