One pot solvothermal synthesis of organic acid coated magnetic iron oxide nanoparticles

Indexación: ScieloABSTRACT In this work we present the synthesis and characterization of iron oxide nanoparticles (IONPs), which were structurally and magnetically characterized. The use of iron salts and an organic acid (l-serine or ascorbic acid) as precursors under solvothermal conditions yielded these coated IONPs. The powder X-ray diffraction pattern of FeO-1 and FeO-2 is consistent with hematite (α-Fe2O3) and hematite-maghemite ((α-Fe2O3/γ-Fe2O3) respectively. The TEM analysis permits to estimate an average size of 10 nm for the FeO-1 sample. The magnetic characterization of the samples through the M(H) plots showed a very low coercivity value for both samples, being 53 Oe for FeO-1 and 10 Oe for FeO-2, indicating the very weak ferromagnetic character of the synthesized iron oxide species. Even though both organic acids under solvothermal conditions permit to obtain coated IONPs in one pot reaction, l-serine produces a more narrow-size distribution

High-quality nodule analysis in spheroidal graphite cast iron using X-ray micro-computed tomography

This work is a continuation of the studies presented in a recent paper by the authors, where a methodology to obtain different nodule quality categories in spheroidal graphite cast iron, was proposed. In this study, an exhaustive analysis of the highest-quality graphite nodules was performed. The experimental methodology involves X-ray micro-computed tomography analysis and digital image post-processing of the high-quality graphite nodule population. Furthermore, different subpopulations were selected, following a nodular size criterion. The procedure involves the evaluation and comparison of the sphericity and compactness distributions and the distances between neighbouring nodules by using ad-hoc image processing software. The results reveal the complementary nature of the sphericity and compactness parameters, which allow classifying, with great accuracy, different nodular quality categories of spheroidal graphite cast iron. Additionally, new viewpoints about the nodular morphology study and the distribution of quality nodules in the metallic matrix was provided, which could be extended to other heterogeneous materials

Resonant Majorana neutrino effects in Δ\DeltaL=2 four-body hyperon decays

We computed the $\Sigma^{-}\to n\pi^+e^-\ell^-$ ($\ell=e,\mu$), $\Xi^-\to \Lambda\pi^+e^-e^-$, and $\Lambda\to p\pi^+e^-e^-$ lepton number violating (LNV) hyperon decays mediated by a resonant Majorana neutrino. The expected hyperon production rate of experiments like BES-III of around $10^6-10^8$ may allow searching for these rare hyperon decays at enough sensitivities. We illustrate the limits on the new heavy mixing parameters derived from these hyperon channels and compare them with other LNV meson decays in similar mass regions of the resonant neutrino state.Comment: 18 pages, 3 figure

Importancia de la Gestión de Personas y Compensaciones, alineadas a los Objetivos Estratégicos Organizacionales.

This essay aims to denote the relevance of a compensation system, when it and its subsystems are aligned with the objectives and strategy of the organization in terms of human resources, considering the different areas or industries where they work. The concepts of monetary and non-monetary compensation, incentives and the four functions of a compensation system for an organization will also be reviewed from theory.Este ensayo tiene como objetivo denotar la relevancia de un sistema de compensaciones, cuando este y sus subsistemas están alineados los objetivos y estrategia de la organización en materia de gestión de personas, considerando los distintos rubros o industrias en donde se desempeñan. También se revisarán desde la teoría los conceptos de compensación monetaria y no monetaria, incentivos y las cuatro funciones de un sistema de compensación para una organización

Reseña a Mito y desarrollo en Bolivia. El giro colonial del gobierno del MAS, de Silvia Rivera Cusicanqui

Reseña de libr

EL burócrata del siglo XXI: De la dictadura racional hacia la democratización de gestión óptima

There has been a debate that has generated controversies among professional circles, which lies in the confrontation of the sacrosanct dogma of the efficiency and effectiveness of public administration and the participation of people in the decisions of public management, including the lack of political participation in this area, against the notion of a State open to citizens, considering the risks in the feasibility of the work itself. It is in this scenario that the civil servant of this century considers the need to reconcile both perspectives, in pursuit of the development of modern public management, which will be analyzed from a perspective of historical evolution and impact on the management of state institutions.Se ha producido un debate que ha generado controversias entre los círculos profesionales, que radica en el enfrentamiento del sacrosanto dogma de la eficiencia y eficacia de administración pública y la participación de las personas en las decisiones de la gestión pública, inclusive se ha legitimado la falta de participación política en esta área, en contra de la noción de un Estado abierto a la ciudadanía, considerando los riegos en la factibilidad de la propia labor. Es en este escenario que el funcionario de este siglo se plantea la necesidad de congeniar ambas perspectivas, en pos del desarrollo de una gestión pública moderna, lo cual se analizará desde una perspectiva de evolución histórica y de impacto en la gestión de las instituciones estatales

Responsabilidade civil do estado por condutas omissivas

O cerne do presente trabalho é o estudo da responsabilidade civil do Estado nas condutas omissivas sob o enfoque do artigo 37, §6º da Constituição Federal, apresentando a enorme divergência doutrinária e jurisprudencial existente quanto à omissão estatal. Será apresentada uma breve evolução histórica, com a explicitação das principais teorias e seus fundamentos, bem como suas influências no direito brasileiro. A seguir será estudado o dispositivo constitucional, com uma análise minuciosa dos institutos nele presentes. Por fim, serão apresentadas as duas principais correntes doutrinárias que se propõem a dar uma solução ao problema, a teoria da responsabilidade subjetiva e a da responsabilidade subjetiva, bem como um estudo profundo de seus respectivos argumentos e jurisprudência existentes

Anisotropic Dark Energy from String Compactifications

We explore the cosmological dynamics of a minimalistic yet generic string-inspired model for multifield dark energy. Adopting a supergravity four-dimensional viewpoint, we motivate the model's structure arising from superstring compactifications involving a chiral superfield and a pure $U(1)$ gauge sector. The chiral sector gives rise to a pair of scalar fields, such as the axio-dilaton, which are kinetically coupled. However, the scalar potential depends on only one of them, further entwined with the vector field through the gauge kinetic function. The model has two anisotropic attractor solutions that, despite a steep potential and thanks to multifield dynamics, could explain the current accelerated expansion of the Universe while satisfying observational constraints on the late-times cosmological anisotropy. Nevertheless, justifying the parameter space allowing for slow roll dynamics together with the correct cosmological parameters, would be challenging within the landscape of string theory. Intriguingly, we find that the vector field, particularly at one of the studied fixed points, plays a crucial role in enabling geodesic trajectories in the scalar field space while realizing slow-roll dynamics with a steep potential. This observation opens a new avenue for exploring multifield dark energy models within the superstring landscape.Comment: Submitted to JHEP. Comments are welcome

Chile: un estado de bienestar inexistente

Chile has experienced a process of radical transformations over the last forty years in the field of social policies, from the attempt to transform towards a socialist sta- te, going through policies to reduce the social welfare apparatus implemented by the military dictatorship, to the benefits social implementations since the return to democracy. However, there is a question raised at the country level, about whether Chile has a Welfare State itself. This question is what will be sought to elucidate in the following pages, which will range from the conception of social vulnerability, the historical evolution of social protection policies, to a detailed analysis regarding the role of the welfare state.Chile ha vivido un proceso de transformaciones radicales durante los últimos cuarenta años en el ámbito de políticas sociales, desde el intento de transformación hacia un Estado socialista, transitando por las políticas de reducción del aparato de bienestar social instaurado por la dictadura militar, hasta los beneficios sociales implementados desde el retorno a la democracia. Sin embargo, existe una pregunta planteada a nivel país, sobre si Chile posee un estado de bienestar propiamente tal. Esta interrogante es la que se buscará dilucidar en las siguientes páginas, que irá desde la concepción de la vulnerabilidad social, la evolución histórica de las políticas de protección social, hasta un análisis detallado respecto al rol del estado de bienestar

Factores que afectan a la producción, a la composición y a los paramentos tecnológicos de la oveja merina de Grazalema

En el presente trabajo se ha realizado el análisis de 6 ganaderías diferentes de la zona de Grazalema. En ellas, durante 4 años, se han tomado un total de 1.614 muestras, en las cuales se han analizado las diferentes variables de leche de oveja Merina de Grazalema, con el objetivo de caracterizar la producción, la composición y la aptitud tecnológica de la leche, para determinar el efecto de la ganadería, el nº de lactación, y el RCS sobre ellos. Los resultados obtenidos muestran que tanto el rebaño, como el nº de lactación y el RCS ejercen una influencia significativa sobre la producción, la composición y las características tecnológicas. Se ha comprobado que al aumentar la vida productiva del animal por encima de la 6ª lactación, se produce un deterioro de la calidad de la leche, que se refleja en una producción más baja, una mala aptitud tecnológica y un aumento de los RCS. Sin embargo, al aumentar el periodo de lactación se observa una mejora en la composición físico-química (debida principalmente al descenso de la producción). Además los resultados señalaron diferencias entre ganaderías. Esto demuestra la influencia de los diferentes factores propios de cada ganadería, como la alimentación, manejo, estado sanitario, etc., sobre los parámetros estudiados. Junto con lo anterior, se ha observado que el aumento en el RCS va a empeorar el porcentaje de la mayoría de los componentes físico-químicos, de la producción lechera, y de los parámetros tecnológicos