Kinetics of the template-directed oligomerization of guanosine 5'-phosphate-2-methylimidazolide: Effect of temperature on individual steps of reactionion

Non-enzymatic, template-directed reactions have been proposed as models for prebiological polynucleotide synthesis. Chemically activated mononucleotides react in the presence of a polynucleotide, acting as the template in a Watson-Crick base-pairing fashing, and form the complementary daughter polynucleotide. Phosphoimidazolide-activated nucleotides have been used successfully as substrates in these reactions. The kinetics of the guanosine 5'-monophosphate-2-methylimidazolide (2-MelmpG) reaction in aqueous pH 8.0 solutions in the presence and in the absence of polycytidylate (poly(C)) were studied, acting as the template at 6, 23, and 37 C. In the absence of the template, the major reaction pathway of 2-MelmpG is hydrolysis of the P-N bond to form the unreactive guanosine 5'-monophosphate (5'-GMP) and 2-methylimidazole. Concentrated solution of 2-MelmpG (greater than 0.02 M) in the absence of the template form only a small amount dinucleotide, (pG)2, but in the presence of poly(C), oligoguanylates, (pG)n with 2 less than or = n less than or = 40, can be detected. We were able to determine the rate constants for individual steps of this reaction. A summary of the conclusions is presented

La apoteosis del investigador y la institucionalización de la profesión académica en Chile

El estudio del profesorado universitario en América Latina revela una profesión académica heterogénea en sus perfiles y funciones, segmentada en sus ámbitos de ejercicio, y estratificada en cuanto a su posición social. La investigación que aquí se reporta, basada en estudios de caso de doce universidades chilenas –con un primer levantamiento de datos en 2001-2002, y un segundo trabajo de terreno en las mismas universidades en 2007-2008– complementa este análisis poniendo de relieve la influencia modeladora del académico investigador sobre el conjunto de la profesión. No obstante su condición de minoría en las universidades chilenas, el perfil del profesor investigador domina tanto en el plano de los ideales, el discurso y los valores, como en la configuración de las políticas y regulaciones que rigen el trabajo académic

A demonstrator for the experimental assessment of the through-process modeling of injection-molded parts made of short-fiber-reinforced polymers

Through process modelling of injection moulded parts is nowadays the industry standard approach to the structural analysis of parts made of short fibre-reinforced polymers. The designer has to face challenging tasks, in order to conduct accurate and reliable analyses. Complex geometries, weld lines and multiple flows make it difficult to transfer results of tests conducted on simple specimens to the assessment of the real parts. We have designed a mould allowing for manufacturing a demonstrator, i.e., a part of sufficiently complex shape, typical of injection-moulded structural parts, allowing for creating different conditions in terms of fibre orientation, presence of weld lines and multiple injection points. The part is designed to be tested under three- or four-point bending conditions. By simulating the test conditions, the designer can compare experimental results with numerical solutions, in order to better understand the potential of the software packages he is using

A demonstrator for the experimental assessment of the through-process modeling of injection-molded parts made of short-fiber-reinforced polymers

Through process modelling of injection moulded parts is nowadays the industry standard approach to the structural analysis of parts made of short fibre-reinforced polymers. The designer has to face challenging tasks, in order to conduct accurate and reliable analyses. Complex geometries, weld lines and multiple flows make it difficult to transfer results of tests conducted on simple specimens to the assessment of the real parts. We have designed a mould allowing for manufacturing a demonstrator, i.e., a part of sufficiently complex shape, typical of injection-moulded structural parts, allowing for creating different conditions in terms of fibre orientation, presence of weld lines and multiple injection points. The part is designed to be tested under three- or four-point bending conditions. By simulating the test conditions, the designer can compare experimental results with numerical solutions, in order to better understand the potential of the software packages he is using

A complete characterization of plateaued Boolean functions in terms of their Cayley graphs

In this paper we find a complete characterization of plateaued Boolean functions in terms of the associated Cayley graphs. Precisely, we show that a Boolean function $f$ is $s$-plateaued (of weight $=2^{(n+s-2)/2}$) if and only if the associated Cayley graph is a complete bipartite graph between the support of $f$ and its complement (hence the graph is strongly regular of parameters $e=0,d=2^{(n+s-2)/2}$). Moreover, a Boolean function $f$ is $s$-plateaued (of weight $\neq 2^{(n+s-2)/2}$) if and only if the associated Cayley graph is strongly $3$-walk-regular (and also strongly $\ell$-walk-regular, for all odd $\ell\geq 3$) with some explicitly given parameters.Comment: 7 pages, 1 figure, Proceedings of Africacrypt 201

Grids of stellar models. VIII. From 0.4 to 1.0 Msun at Z=0.020 and Z=0.001, with the MHD equation of state

We present stellar evolutionary models covering the mass range from 0.4 to 1 Msun calculated for metallicities Z=0.020 and 0.001 with the MHD equation of state (Hummer & Mihalas, 1988; Mihalas et al. 1988; D\"appen et al. 1988). A parallel calculation using the OPAL (Rogers et al. 1996) equation of state has been made to demonstrate the adequacy of the MHD equation of state in the range of 1.0 to 0.8 Msun (the lower end of the OPAL tables). Below, down to 0.4 Msun, we have justified the use of the MHD equation of state by theoretical arguments and the findings of Chabrier & Baraffe (1997). We use the radiative opacities by Iglesias & Rogers (1996), completed with the atomic and molecular opacities by Alexander & Fergusson (1994). We follow the evolution from the Hayashi fully convective configuration up to the red giant tip for the most massive stars, and up to an age of 20 Gyr for the less massive ones. We compare our solar-metallicity models with recent models computed by other groups and with observations. The present stellar models complete the set of grids computed with the same up-to-date input physics by the Geneva group [Z=0.020 and 0.001, Schaller et al. (1992), Bernasconi (1996), and Charbonnel et al. (1996); Z=0.008, Schaerer et al. (1992); Z=0.004, Charbonnel et al. (1993); Z=0.040, Schaerer et al. (1993); Z=0.10, Mowlavi et al. (1998); enhanced mass loss rate evolutionary tracks, Meynet et al. (1994)].Comment: Accepted for publication in A&A Supplement Serie

Analysis of the dependence of the tensile behaviour of a short fibre reinforced polyamide upon fibre volume fraction, length and orientation

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