Fourier Mukai Transforms for Gorenstein Schemes

We extend to singular schemes with Gorenstein singularities or fibered in schemes of that kind Bondal and Orlov's criterion for an integral functor to be fully faithful. We also contemplate a criterion for equivalence. We offer a proof that is new even if we restrict to the smooth case. In addition, we prove that for locally projective Gorenstein morphisms, a relative integral functor is fully faithful if and only if its restriction to each fibre also is it. These results imply the invertibility of the usual relative Fourier-Mukai transform for an elliptic fibration as a direct corollary.Comment: Final version. To appear in Advances in Mathematic

C_xN_y : new carbon nitride organic photocatalysts

The search for metal-free and visible light-responsive materials for photocatalytic applications has attracted the interest of not only academics but also the industry in the last decades. Since graphitic carbon nitride (g-C3N4) was first reported as a metal-free photocatalyst, this has been widely investigated in different light-driven reactions. However, the high recombination rate, low electrical conductivity, and lack of photoresponse in most of the visible range have elicited the search for alternatives. In this regard, a broad family of carbon nitride (CxNy) materials was anticipated several decades ago. However, the attention of the researchers in these materials has just been awakened in the last years due to the recent success in the syntheses of some of these materials (i.e., C3N3, C2N, C3N, and C3N5, among others), together with theoretical simulations pointing at the excellent physico-chemical properties (i.e., crystalline structure and chemical morphology, electronic configuration and semiconducting nature, or high refractive index and hardness, among others) and optoelectronic applications of these materials. The performance of CxNy, beyond C3N4, has been barely evaluated in real applications, including energy conversion, storage, and adsorption technologies, and further work must be carried out, especially experimentally, in order to confirm the high expectations raised by simulations and theoretical calculations. Herein, we have summarized the scarce literature related to recent results reporting the synthetic routes, structures, and performance of these materials as photocatalysts. Moreover, the challenges and perspectives at the forefront of this field using CxNy materials are disclosed. We aim to stimulate the research of this new generation of CxNy-based photocatalysts, beyond C3N4, with improved photocatalytic efficiencies by harnessing the striking structural, electronic, and optical properties of this new family of materials

Carbonaceous materials : the beauty of simplicity

The current mandates of a sustainable society and circular economy lead to the request that materials chemistry, but also chemistry as such, has to become significantly redesigned. Changes include commonplaces as the glassware we use, the minimization of wastes and side products or replacement strategies in the materials choice, among others. In this context, “carbons” are very versatile and already have found their place in a myriad of applications for a “carbon-neutral” society. They already take key enabling positions for sensors and biomaterials preparation, as energy conversion and storage electrode, or as effluent remediation sorbents. Herein, we describe how carbon chemistry can be again re-designed to outperform benchmark materials in a number of fields, especially in energy storage, (electro)catalysis, as sorbent, but also in a new chemistry of the confined state

“We are here!” Oxygen functional groups in carbons for electrochemical applications

Heteroatom doping of carbon networks may introduce active functional groups on the surface of the material, induce electron density changes that alter the polarity of the carbon surface, promote the formation of binding sites for molecules or ions, or make the surface catalytically active for different reactions, among many other alterations. Thus, it is no surprise that heteroatom doping has become a well-established strategy to enhance the performance of carbon-based materials for applications ranging from water remediation and gas sorption to energy storage and conversion. Although oxygen functionalization is sometimes inevitable (i.e., many carbon precursors contain oxygen functionalities), its participation in carbon materials performance is often overlooked on behalf of other heteroatoms (mainly nitrogen). In this Mini-review, we summarize recent and relevant publications on the effect that oxygen functionalization has on carbonaceous materials performance in different electrochemical applications and some strategies to introduce such functionalization purposely. Our aim is to revert the current tendency to overlook it and raise the attention of the materials science community on the benefits of using oxygen functionalization in many state-of-the-art applications

Anteproyecto de fabricacion de una prensa hidraulica para moldeo de piezas de goma

223 p.El anteproyecto que presento, tiene como finalidad realizar un estudio técnico-económico para la fabricación de una prensa hidráulica para vulcanizado de goma, en el que se abarcan áreas tan importantes como, el diseño mecánico, la oleohidráulica y la electricidad. Cada una de estas areas est.§ definida en los capítulos posteriores de acuerdo al siguiente detalle. En el CAPITULO 1, encontramos una breve Introducción. En el CAPITULO 2, definimos los diferentes métodos de moldeo. El CAPITULO 3, nos muestra una breve descripción para el diseño de los moldes. El CAPITULO 4, nos explica las Técnicas de construcción de moldes. El CAPITULO 5, define a la prensa propiamente tal y sus tipos mas comunes. El CAPITULO 6, nos muestra la operación de moldeo. CAPITULO 7, en este capitulo tratamos finalmente las operaciones de acabado, fundamentales en el control de calidad del producto vulcanizado. En el CAPITULO 8, aplicamos los conocimientos de Ingeniería básica y efectuamos el diseño de la prensa. El CAPITULO 9, trata los procesos de Montaje y fabricación. El CAPITULO 10, se entrega un Instructivo de Operación para el funcionamiento de la prensa. En el CAPITULO 11, se hace una evaluación económica del anteproyecto. Finalmente en el CAPITULO 12, se analiza La factibilidad del anteproyecto. Cada uno de los capítulos nos enfrentara a temas cotidianos, tratados en las fabricas de productos de goma. Debemos agregar además, que es indudable que existen muchas otras formas de vulcanizado de goma pero el que mayormente se utiliza, es el tratado en esta tesis, por tanto, servirá como Introducción a este campo tan amplio y útil de la fabricación industrial

Stratified regression Monte-Carlo scheme for semilinear PDEs and BSDEs with large scale parallelization on GPUs

In this paper, we design a novel algorithm based on Least-Squares Monte Carlo (LSMC) in order to approximate the solution of discrete time Backward Stochastic Differential Equations (BSDEs). Our algorithm allows massive parallelization of the computations on multicore devices such as graphics processing units (GPUs). Our approach consists of a novel method of stratification which appears to be crucial for large scale parallelization

Influencia del clima laboral en el desempeño de los trabajadores del resto- bar Candelaria Cusco, 2022

La presente investigación titulada: Influencia del clima laboral en el desempeño de los trabajadores del resto- bar Candelaria Cusco, 2022. Cuyo objetivo general del presente estudio es determinar la influencia del clima laboral en el desempeño de trabajo de los trabajadores del resto-bar Candelaria Cusco, 2022. La metodología desarrollada fue básica con un enfoque cuantitativo apoyado en un diseño no experimental, considerando una muestra representativa de 30 trabajadores de la empresa en investigación. Se utilizó la técnica de la encuesta, bajo la aplicación del instrumento de cuestionario. En los resultados se logró evidenciar una correlación positiva muy fuerte donde el r= 0,971, sumado a la significancia de p=0,002 la cual es menor a 0.05, en consecuencia se admite la hipótesis alterna y se desestima la nula. Por ello se pudo concluir que existe una influencia entre el clima laboral y el desempeño laboral en el desempeño de los trabajadores del restobar Candelaria