Frobenius pairs in abelian categories: correspondences with cotorsion pairs, exact model categories, and Auslander-Buchweitz contexts

In this work, we revisit Auslander-Buchweitz Approximation Theory and find some relations with cotorsion pairs and model category structures. From the notions of relatives generators and cogenerators in Approximation Theory, we introduce the concept of left Frobenius pairs $(\mathcal{X},\omega)$ in an abelian category $\mathcal{C}$. We show how to construct from $(\mathcal{X},\omega)$ a projective exact model structure on $\mathcal{X}^\wedge$, as a result of Hovey-Gillespie Correspondence applied to two compatible and complete cotorsion pairs in $\mathcal{X}^\wedge$. These pairs can be regarded as examples of what we call cotorsion pairs relative to a thick subcategory of $\mathcal{C}$. We establish some correspondences between Frobenius pairs, relative cotorsion pairs, exact model structures and Auslander-Buchweitz contexts. Finally, some applications of these results are given in the context of Gorenstein homological algebra by generalizing some existing model structures on the categories of modules over Gorenstein and Ding-Chen rings, and by encoding the stable module category of a ring as a certain homotopy category. We also present some connections with perfect cotorsion pairs, covering classes, and cotilting modules.Comment: 54 pages, 10 figures. The statement and proof of 2.6.21 was corrected. Typos corrected. Section 4 was improved, and new results in Section 5 were adde

Zinc(II) coordination polymers with pseudopeptidic ligands

Two new phenyl-bridged pseudopeptidic ligands have been prepared and structurally characterised. The nature of the ligands’ substituents play an important role in the nature of the solid state structure yielding either hydrogen bonded linked sheets of molecules or infinite hydrogen bonded networks. Both these ligands were reacted with a range of zinc(II) salts with the aim of synthesising coordination polymers and networks and exploring the role that anions could play in determining the final structure. The crystal structures of four of these systems (with ZnSO4 and ZnBr2) were determined; in one case, a 3D coordination network was obtained where zinc–ligand coordination bonds generated the 3D arrangements. Three other 3D networks were obtained by anion-mediated hydrogen bonding of coordination 1D chains or 2D sheets. These four very different structures highlight the important role played by the ligands’ substituents and the counteranions present in the system

Chalcolithic archaeological evidences in Cerro del Castillo de Medellín (Badajoz, Spain): sondage ‘G’

Este trabajo recoge las evidencias materiales de época calcolítica documentadas en las diferentes intervenciones arqueológicas llevadas a cabo en las laderas del cerro del Castillo de Medellín (Badajoz). La aparición de varias estructuras y un significativo lote de materiales cerámicos, avalan la existencia de un momento de ocupación de este estratégico punto del valle medio del Guadiana durante el III Milenio a.C., lo que suma un punto más en el dinámico paisaje del poblamiento calcolítico de este territorioThis work presents material evidence from Chalcolithic times documented through the different archaeological interventions undertaken on the side of the hill upon which the Medellín Castle stands (Badajoz). The appearance of different structures and a significant lot of ceramic materials support the existence of a moment at which this strategic point in the Middle Valley of the Guadiana River was occupied during the third millennium BC – a fact which is yet another important point to be studied in terms of the dynamic panorama of Chalcolithic settlement in this are

Synthesis and Luminescent Properties of Silicon Nanocrystals

Nowadays, study of silicon-based visible light-emitting devices has increased due to large-scale microelectronic integration. Since then different physical and chemical processes have been performed to convert bulk silicon (Si) into a light-emitting material. From discovery of Photoluminescence (PL) in porous Silicon by Canham, a new field of research was opened in optical properties of the Si nanocrystals (Si-NCs) embedded in a dielectric matrix, such as SRO (silicon-rich oxide) and SRN (silicon-rich nitride). In this respect, SRO films obtained by sputtering technique have proved to be an option for light-emitting capacitors (LECs). For the synthesis of SRO films, growth parameters should be considered; Si-excess, growth temperature and annealing temperature. Such parameters affect generation of radiative defects, distribution of Si-NCs and luminescent properties. In this chapter, we report synthesis, structural and luminescent properties of SRO monolayers and SRO/SiO2 multilayers (MLs) obtained by sputtering technique modifying Si-excess, thickness and thermal treatments

Low-temperature oxidation effects on the morphological and structural properties of hexagonal Zn nanodisks

Ambient-atmosphere oxidation in the temperature range of 90-450 C was performed over Zn films composed by well-faceted hexagonal nanodisks, which were deposited by thermal evaporation. Morphological and structural properties of oxidized Zn nanodisks were studied by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and Raman scattering measurements. It was found that Zn nanodisks keep its original shape only when they are annealed at 90 or 150 C. Smooth oxidation ocurred only on the rectangular faces of Zn nandodisks heated at 150 C. Thermal oxidation at 250 C favored growth of ZnO nanoneedles over the surface of the Zn nanodisks. Hexagonal-shape of Zn nanodisks was transformed completely into a complex morphology composed by different shaped particles, with further increase in oxidation temperature to 450 C

Síntesis y caracterización de resinas a base de aceite de linaza epoxidado y xilitol

En los últimos años el uso de polímeros ha generado una gran cantidad de residuos, esto ha propiciado la búsqueda de materiales alternativos, amigables con el medio ambiente, no tóxicos y biodegradables, que puedan remplazar a aquellos derivados del petróleo en la síntesis de materiales poliméricos (Abdullah y Salimon, 2010). El aceite de linaza es una excelente opción para la obtención de sustratos, debido a la cantidad de enlaces insaturados presentes en su estructura, los cuales pueden modificarse químicamente para la introducción de grupos funcionales fácilmente polimerizables. El objetivo del presente trabajo fue sintetizar y caracterizar monómeros a base de aceite de linaza epoxidado (ALE), funcionalizado con Xilitol (Xil) así como sus respectivos polímeros y la medición de sus constantes dieléctricas; las etapas del proyecto son: 1) Epoxidación del aceite de linaza, 2) Funcionalización del ALE con Xil al 50% y 100%, 3) Obtención de los polímeros reticulados (resinas) y 4) Obtención de las constantes dieléctricas de los polímeros reticulados.In recent years the use of polymers has generated a lot of waste, this has prompted the search of alternative materials, friendly with the environment, non-toxic and biodegradable, which could replace those derived from petroleum in the synthesis of polymeric materials. Linseed oil is an excellent choice for obtaining substrates, due to the number of unsaturated bonds present in its structure, which can be chemically modified to introduce easily polymerizable functional groups. The aim of this study was to synthesize and characterize epoxidized linseed oil (ALE) monomers functionalized with Xylitol (Xil) and their respective polymers and measuring their dielectric constants; the parts of the project are: 1) epoxidation of linseed oil, 2) Functionalization of ALE with Xil at 50% and 100%, 3) Obtaining crosslinked polymers (resins) and 4) Getting the dielectric constants of the crosslinked polymers

Análisis locacional de los yacimiento pétreos para la planeación territorial de infraestructura: El caso de la red pavimentada de Veracruz, México

The aim of the present work is to highlight the importance of territorial planning in the sustainable use of the raw material deposits located in the state of Veracruz, ranking first at the national level according to the National Inventory of Raw Material Deposits (NIRMD) 2011/2012 of the Secretariat of Communications and Transport (SCT). Raw material deposits are geological deposits of materials essential for the construction, maintenance and modernization of the basic infrastructure -communications and transport, electrical and hydraulic infrastructures-,social infrastructure–facilities to supply services and housing infrastructure-, and productive infrastructure –works aimed at the production and marketing of goods and services.La finalidad de este trabajo es destacar la importancia de la planeación territorial para el aprovechamiento sustentable de los yacimientos pétreos con que cuenta el estado de Veracruz, el cual ocupa el primer lugar a nivel nacional de acuerdo con el Inventario Nacional de Bancos de Materiales1 (INBM) 2011/2012 de la Secretaría de Comunicaciones y Transportes (SCT). Los bancos de materiales son aquellos yacimientos geológicos de materiales indispensables para la construcción, mantenimiento y modernización de la infraestructura básica: comunicaciones,  transportes, hidráulica y eléctrica, infraestructura social: instalaciones para suministrar servicios a la población y habitacional, e  infraestructura: productiva obras destinadas a la producción y comercialización de bienes y servicios