Controlling eutrophication by means of water recirculation: An optimal control perspective

In this work, the artificial recirculation of water is presented and analyzed, from the perspective of the optimal control of partial differential equations, as a tool to prevent eutrophication effects in large waterbodies. A novel formulation of the environmental problem, based on the coupling of nonlinear models for hydrodynamics, water temperature and concentrations of the different species involved in the eutrophication processes, is introduced. After a complete and rigorous analysis of the existence of optimal solutions, a full numerical algorithm for their computation is proposed. Finally, some numerical results for a realistic scenario are shown, in order to prove the efficiency of our approachThe authors would like to thank the anonymous referees for their interesting comments, suggestions and corrections, as they have greatly contributed to improve the quality of the manuscript. The authors were partially supported by Xunta de Galicia, Spain, project ED431C 2019/02, and by the Agencia Estatal de Investigación (AEI) of Spain under grant MTM2016-75140-P, co-financed by the European Community fund FEDERS

Revisiting the Decomposition Process of Tetrahydrate Co(II) Acetate: A Sample’s Journey through Temperature.

Cobalt oxides, CoO and Co3O4, were obtained from Co (II) acetate tetrahydrate. The thermal decomposition pathway of the starting product was followed by combining thermogravimetric analysis and in situ X-ray thermodiffraction. Under a nitrogen atmosphere, cobalt monoxide with Zn-blende and rocksalt polymorphs could be obtained almost as single phases at 330 and 400 °C, respectively. In addition to these oxides, a Co (II) oxyacetate, Co3O(CH3COO)4, was stabilized as an intermediate phase. Under an air atmosphere, Co3O4 (spinel structure type) was obtained as the only final product. The involved phases in this thermal decomposition process were characterized with scanning and transmission electron microscopy (SEM and TEM, respectively).Depto. de Química InorgánicaFac. de Ciencias QuímicasTRUEpu

SrMnO3 thermochromic behavior governed by size-dependent structural distortions

The influence of particle size in both the structure and thermochromic behavior of 4H-SrMnO related perovskite is described. Microsized SrMnO suffers a structural transition from hexagonal (P6/mmc) to orthorhombic (C222) symmetry at temperature close to 340 K. The orthorhombic distortion is due to the tilting of the corner-sharing MnO units building the 4H structural type. When temperature decreases, the distortion becomes sharper reaching its maximal degree at ∼125 K. These structural changes promote the modification of the electronic structure of orthorhombic SrMnO phase originating the observed color change. nano-SrMnO adopts the ideal 4H hexagonal structure at room temperature, the orthorhombic distortion being only detected at temperature below 170 K. A decrease in the orthorhombic distortion degree, compared to that observed in the microsample, may be the reason why a color change is not observed at low temperature (77 K)

I.amAble: la ciencia (química) al alcance de toda la sociedad

En este proyecto de innovación, que nace con vocación de continuar en años sucesivos, se persigue mejorar la calidad de la formación de los estudiantes de la Facultad de Ciencias Químicas (F. CC.QQ.) en el ámbito de la docencia teórico-práctica y de la divulgación científica. El trabajo ha consistido en la preparación de unos experimentos prácticos para llevarlos a cabo en centros educativos no universitarios en los que se ha tenido en cuenta la participación conjunta de personas con y sin diversidad funcional, desde una perspectiva inclusiva colaborativa. Estas actividades las han realizado los estudiantes bajo la supervisión de profesores (PDI) y personal de administración y servicios (PAS). Los experimentos se han recogido en fichas didácticas para facilitar su desarrollo y aplicación por parte de otros usuarios. En estas fichas se explica detalladamente cómo realizar las experiencias en formato de taller. Las fichas de los talleres realizados están disponibles en una página web vinculada a la Universidad Complutense bajo el título I.amAble (iamable.ucm.es). Está página ha sido construida por un estudiante de la Facultad de Informática , bajo la supervisión de profesionales, tanto de esa facultad como del Instituto de Tecnología del Conocimiento, y está abierta a contribuciones similares de otras facultades y otras instituciones. La página web está diseñada de manera que resulte lo más intuitiva y accesible posible para todo tipo de público. Entre todos los experimentos se han elegido cuatro para llevarlos a la práctica en centros educativos como actividades inclusivas en las que han participado conjuntamente personas con y sin discapacidad. Con este proyecto se pretende mejorar la calidad docente al ofrecer a los estudiantes la posibilidad de aprender enseñando mediante una actividad semipresencial. El desarrollo por parte de los estudiantes de competencias transversales en educación y en divulgación de la ciencia facilitarán algunas salidas profesionales en el ámbito educativo formal (centros de enseñanza) o informal (museos, animación sociocultural). Otro aspecto importante a resaltar es la potenciación de la colaboración entre todos los miembros de la institución universitaria. Este proyecto pretende contribuir a la mejora de la cultura científica, así como al establecimiento de puentes entre la UCM y la sociedad a la que debe servir. Finalmente, es importante subrayar que incidirá en la inclusión de las personas con discapacidad como parte de la sociedad, a través del acercamiento compartido a la ciencia (Dimensiones de inclusión social y derechos de Schalock; NAVAS MACHO, P. y otros, 2012. Derechos de las personas con discapacidad intelectual: implicaciones de la Convención de Naciones Unidas. Siglo Cero. 43 (243): 7-28.)

Synthesis of 4H-SrMnO3.0 nanoparticles from a molecular precursor and their topotactic reduction pathway identified at atomic scale

Stoichiometric 4H-SrMnO3.0 nanoparticles have been synthesized from thermal decomposition of a new molecular heterometallic precursor [SrMn(edta)(H2O)5]·3/2H 2O whose crystal structure has been solved by single crystal X-ray diffraction. From this precursor, highly homogeneous 4H-SrMnO3.0 nanoparticles, with average particle size of 70 nm, are obtained. The agglomeration of these nanoparticles maintains the sheet-assembling morphology of the metal-organic compound. Local structural information, provided by atomically resolved microscopy techniques, shows that 4H-SrMnO3.0 nanoparticles exhibit the same general structural features as the bulk material, although structural disorder, due to edge dislocations, is observed. The nanometric particle size enables a topotactic reduction process at low temperature stabilizing a metastable 4H-SrMnO2.82 phase. The oxygen deficiency is accommodated through extra cubic layers breaking the...chch... 4H-sequence. These defect areas are Mn3+ rich, as evidenced by high energy resolution EELS data. Magnetic characterization of nano-SrMnO 3.0 shows significant variations with respect to the bulk material. Besides the dominant antiferromagnetic interactions, a weak ferromagnetic contribution as well as exchange bias and a glassy-like component are present. After the reduction process, the stabilization of Mn3+ in the 4H-structure gives rise to magnetic anomalies in the 40-60 K temperature range. The origin of such magnetic features is discussed. © 2014 American Chemical Society.Financial support through research projects CSD2009-00013, MAT2011-23068, and MAT2011-27470-C02-02 is acknowledged.Peer Reviewe

Understanding internal mechanisms to obtain nanomanganites by hydrothermal synthesis: The particular case of 4H-SrMnO3

We have determined why hydrothermal synthesis is not an adequate method to obtain nanoparticles in the Sr-Mn-O system. At high KOH concentration, which is more appropriate for obtaining nanoparticles, Sr is partially incorporated inside an intermediate (K,Sr)xMnO2·nH2O layered phase that prevents the formation of 4H-nanoparticles. Numerous experiments have been performed, screening the parameters involved in such processes (precursors, pH, temperature, etc.) in order to understand their influence on the shape, size, and purity of the 4H-final product. On analyzing the experimental results obtained by XRD, TEM, TGA, and EDS, among others, some peculiarities of the synthetic procedure were detected, including the appearance of side phases, SrMn3O6–x nanoribbons or the above-mentioned birnessite-type (K,Sr)xMnO2·nH2O phase, and the insertion of K+ within the 4H-phase prepared at high KOH concentration. Magnetic features are also discussed

Curso de nivelación de Química para los Grados en Geología e Ingeniería Geológica

Depto. de Química InorgánicaFac. de Ciencias QuímicasFALSEsubmitte