Cp2TiCl/D2O/Mn, a formidable reagent for the deuteration of organic compounds

Cp2TiCl/D2O/Mn is an efficient combination, sustainable and cheap reagent that mediates the D-atom transfer from D2O to different functional groups and can contribute to the synthesis of new deuterated organic compounds under friendly experimental conditions and with great economic advantages.The Spanish MICINN (Project CTQ2015-70724-R)University of Sevill

Cp2TiCl/D2O/Mn, a formidable reagent for the deuteration of organic compounds

Cp2TiCl/D2O/Mn is an efficient combination, sustainable and cheap reagent that mediates the D-atom transfer from D2O to different functional groups and can contribute to the synthesis of new deuterated organic compounds under friendly experimental conditions and with great economic advantages.The Spanish MICINN (Project CTQ2015-70724-R)University of Sevill

Divorce risk factors and their variation over time in Spain

The aim of this article is to analyse the determinants of marriage dissolution in Spain and their variation over time for women married between 1949 and 2006. Data are drawn from the Survey of Fertility, Family and Values of 2006. The article analyses the transition from first marriage to marital dissolution for couples who married in two eras: one prior to the Divorce Law of 1981, during which social and legal barriers to dissolution were many, and one in the period after the law was introduced, during which barriers to marriage dissolution were far fewer. Analyses are conducted using a continuous time event history model. The results indicate some similarities between Spain and other countries, such as the positive relationship between the typical features of unconventional families and marital dissolution, but also some specific differences, such as an increase in the importance of premarital pregnancy and/or not having children. It is also important to stress the declining importance of socio-economic variables, such as education and the labour market situation of women.age heterogamy, children and divorce, divorce, education and divorce, event history analysis, parental divorce, premarital children, premarital cohabitation, premarital pregnancy, separation

Diffusion-reaction modelling of the degradation of oil-well cement exposed to carbonated brine

The essential aspects of a diffusion-reaction model in development for the degradation process of oil-well cement exposed to carbonated brine are presented in this paper. The formulation consists of two main diffusion/reaction field equations for the concentrations of aqueous calcium and carbon species in the hardened cement paste pore solution, complemented by a number of chemical kinetics and chemical equilibrium equations. The volume fraction distribution of the solid constituents of the hardened cement paste and the reaction products evolve with the progress of the reaction, determining the diffusivity properties of the material. A sensitivity analysis of some parameters of the model is presented to illustrate the capabilities to reproduce realistically some aspects of the degradation process.The essential aspects of a diffusion-reaction model in development for the degradation process of oil-well cement exposed to carbonated brine are presented in this paper. The formulation consists of two main diffusion/reaction field equations for the concentrations of aqueous calcium and carbon species in the hardened cement paste pore solution, complemented by a number of chemical kinetics and chemical equilibrium equations. The volume fraction distribution of the solid constituents of the hardened cement paste and the reaction products evolve with the progress of the reaction, determining the diffusivity properties of the material. A sensitivity analysis of some parameters of the model is presented to illustrate the capabilities to reproduce realistically some aspects of the degradation process

Diffusion-reaction modelling of the degradation of oil-well cement exposed to carbonated brine

The essential aspects of a diffusion-reaction model in development for the degradation process of oil-well cement exposed to carbonated brine are presented in this paper. The formulation consists of two main diffusion/reaction field equations for the concentrations of aqueous calcium and carbon species in the hardened cement paste pore solution, complemented by a number of chemical kinetics and chemical equilibrium equations. The volume fraction distribution of the solid constituents of the hardened cement paste and the reaction products evolve with the progress of the reaction, determining the diffusivity properties of the material. A sensitivity analysis of some parameters of the model is presented to illustrate the capabilities to reproduce realistically some aspects of the degradation process.The essential aspects of a diffusion-reaction model in development for the degradation process of oil-well cement exposed to carbonated brine are presented in this paper. The formulation consists of two main diffusion/reaction field equations for the concentrations of aqueous calcium and carbon species in the hardened cement paste pore solution, complemented by a number of chemical kinetics and chemical equilibrium equations. The volume fraction distribution of the solid constituents of the hardened cement paste and the reaction products evolve with the progress of the reaction, determining the diffusivity properties of the material. A sensitivity analysis of some parameters of the model is presented to illustrate the capabilities to reproduce realistically some aspects of the degradation process

Diffusion-reaction modelling of the degradation of oil-well cement exposed to carbonated brine

The essential aspects of a diffusion-reaction model in development for the degradation process of oil-well cement exposed to carbonated brine are presented in this paper. The formulation consists of two main diffusion/reaction field equations for the concentrations of aqueous calcium and carbon species in the hardened cement paste pore solution, complemented by a number of chemical kinetics and chemical equilibrium equations. The volume fraction distribution of the solid constituents of the hardened cement paste and the reaction products evolve with the progress of the reaction, determining the diffusivity properties of the material. A sensitivity analysis of some parameters of the model is presented to illustrate the capabilities to reproduce realistically some aspects of the degradation process.The essential aspects of a diffusion-reaction model in development for the degradation process of oil-well cement exposed to carbonated brine are presented in this paper. The formulation consists of two main diffusion/reaction field equations for the concentrations of aqueous calcium and carbon species in the hardened cement paste pore solution, complemented by a number of chemical kinetics and chemical equilibrium equations. The volume fraction distribution of the solid constituents of the hardened cement paste and the reaction products evolve with the progress of the reaction, determining the diffusivity properties of the material. A sensitivity analysis of some parameters of the model is presented to illustrate the capabilities to reproduce realistically some aspects of the degradation process

Energy transfer between colloids via critical interactions

We report the observation of a temperature-controlled synchronization of two Brownian-particles in a binary mixture close to the critical point of the demixing transition. The two beads are trapped by two optical tweezers whose distance is periodically modulated. We notice that the motion synchronization of the two beads appears when the critical temperature is approached. In contrast, when the fluid is far from its critical temperature, the displacements of the two beads are uncorrelated. Small changes in temperature can radically change the global dynamics of the system. We show that the synchronisation is induced by the critical Casimir forces. Finally, we present the measure of the energy transfers inside the system produced by the critical interaction.Comment: 8 pages, 7 figure

Non-standard negation in modern English: a corpus-based study of four salient features

El sistema de polaridad negativa en inglés ha sido objeto de amplio estudio en las últimas décadas. La mayoría de los lingüistas han prestado atención a una serie de fenómenos dentro de este sistema que no observan lo que se considera la regla general. En este artículo me centraré en cuatro aspectos de la negación que no siguen las normas estándar y que cada vez son más frecuentes en el lenguaje utilizado por los hablantes nativos de inglés: la forma verbal negativa ain’t, la coletilla invariable innit, la negación múltiple y el uso del adverbio never como forma negativa de pasado.Para el análisis de estas formas negativas, me referiré, en primer lugar, a su tratamiento en las principales gramáticas del inglés de referencia y, luego, a los resultados del análisis de datos extraídos de varios corpus y de otras fuentes. En la sección final se hacen una serie de consideraciones sobre las implicaciones de todo lo anterior para la enseñanza de este punto gramatical en el ámbito universitario.Negative polarity in English has been extensively studied in the last decades. Most grammarians draw our attention to a number of phenomena within this system that do not conform to what is regarded as the general rule. In this paper I will focus on four main features of negation which precisely do not follow the standard but which are becoming more and more frequent in the language of native speakers of English: the negative verbal form ain’t, the invariable question tag innit, negative concord and the use of the negative adverb never as a past time negator.For the discussion of these negative features, I will refer to the accounts provided by the modem descriptive grammars as well as to the analysis of data extracted from several corpora and other sources. Some reflections are made in the final part on the implications that all this may have for the actual teaching of this area at the university level

Desarrollo de las competencias matemáticas en la formación del ingeniero industrial

El objeto de estudio de este proyecto se fundamentó en la ingeniería didáctica, desarrollada por Michele Artigue. Es por esto que, en la presente investigación la metodología fue desarrollada a mediano plazo con el objeto de establecer las dificultades que se le podrían presentar a un estudiante de primer semestre de ingeniería al resolver un problema. Lo anterior se hizo a través del diseño de un modelo didáctico, el cual se caracteriza por un esquema experimental basado en realizaciones didácticas como: la concepción, realización, observación y análisis de secuencias de enseñanza. Así, se partió de un diagnóstico, el diseño de unos instrumentos denominados talleres, la aplicación y la evaluación en cuatro momentos denominados fases. Como consecuencia de lo anterior, con el fin de dar una visión general al problema de investigación, se formuló una serie de interrogantes fundamentales que permitiera guiar este proceso dentro de la educación superior –específicamente en la Universidad Cooperativa de Colombia, con el propósito de detectar las dificultades que se presentan frecuentemente en el proceso enseñanza–aprendizaje de las matemáticas por competencias en estudiantes de primer semestre de ingeniería industrial y sugerir alternativas didácticas. De ahí que, se planteó como objetivo de la investigación: Construir una situación didáctica para el desarrollo de las competencias matemáticas en estudiantes de Ingeniería Industrial de la Universidad Cooperativa de Colombia. Por consiguiente, con la construcción de la situación didáctica se logró el objetivo enunciado en el trabajo de investigación, ya que permitió establecer avances significativos en los estudiantes en el momento de plantear, resolver y analizar una situación problema