Phase diagram and magnetic properties of La1−x_{1-x}Cax_xMnO3_3 compound for 0≤x≤0.230\leq x \leq 0.23

In this article a detailed study of La$_{1-x}$Ca$_x$MnO$_3$ ($0\leq x \leq 0.23$) phase diagram using powder x-ray diffraction and magnetization measurements is presented. Unfortunately, in the related literature no properly characterized samples have been used, with consequence the smearing of the real physics in this complicated system. As the present results reveal, there are two families of samples. The first family concerns samples prepared in atmosphere ($P({\rm O}_2)=0.2$ Atm) which are all ferromagnetic with Curie temperature rising with $x$. The second family concerns samples, where a post annealing in nearly zero oxygen partial pressure is applied. These samples show a canted antiferromagnetic structure for $0\leq x \leq 0.1$ below $T_N$, while for $0.125\leq x <0.23$ an unconventional ferromagnetic insulated phase is present below $T_c$. The most important difference between nonstoichiometric and stoichiometric samples concerning the magnetic behavior, is the anisotropy in the exchange interactions, in the stoichiometric samples putting forward the idea that a new orbital ordered phase is responsible for the ferromagnetic insulating regime in the La$_{1-x}$Ca$_x$MnO$_3$ compound

Rectangular quantum dots in high magnetic fields

We use density-functional methods to study the effects of an external magnetic field on two-dimensional quantum dots with a rectangular hard-wall confining potential. The increasing magnetic field leads to spin polarization and formation of a highly inhomogeneous maximum-density droplet at the predicted magnetic field strength. At higher fields, we find an oscillating behavior in the electron density and in the magnetization of the dot. We identify a rich variety of phenomena behind the periodicity and analyze the complicated many-electron dynamics, which is shown to be highly dependent on the shape of the quantum dot.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

The use of smartphones and tablets in childhood education. A research proposal to empower children

Resumen: El ecosistema mediático actual y la omnipresencia de pantallas se han convertido en un elemento protagónico en la sociedad hiperconectada. Cada vez a edades más tempranas los menores, denominados como nativos digitales, están en contacto con la tecnología. Hoy en día contamos con numerosos estudios que confirman el contacto directo con dispositivos electrónicos y tecnología móvil, sin embargo, existe una marcada carencia de investigaciones que den voz a la infancia y que muestren su óptica e intereses. Ante esta necesidad y teniendo en cuenta el derecho de la infancia a participar y a ser escuchada, se ha diseñado una herramienta que permita visibilizar sus intereses y darles voz. El instrumento está elaborado según tres dimensiones: provisión, protección y participación que se estructuran entorno a diferentes categorías que justifican el valor de las diferentes técnicas de recogida de información que componen el instrumento. La herramienta se utilizará en ambientes adecuados para la participación buscando espacios conocidos para los niños, cómodos y en los que no se sientan intimidados ya que el instrumento se pasará a los niños por parejas o por tríos para mitigar, en la medida de lo posible, la disparidad de poder del adulto respecto a los pequeños.Abstract: The current media ecosystem and the omnipresence of screens have become leading elements into hyperconnected society. Minors have been appointed as digital natives and they are in touch with technology at youngest ages. Today we have a lot of studies that confirm real contact with electronic devices and mobile technology, however there is a remarked lack of researches that attributes voice to children and it allow them to show their views and their interests. Because of this, we need take into account the right of children to participate and the right to be heard. In this way we have designed a tool that allows us to show their interests; a tool which allows us to give voice to children. The instrument has been built according to three dimensions: provision, protection and participation which are designed around different categories. These categories justify the value of different techniques which are made up the instrument. In this way, we used it to obtain information. We will use this tool in appropriate environments for participation; we will be looking for familiar spaces for children, comfortable environments in which they do not feel intimidated. The instrument will be applied to children in little groups; we will use this technique in order to delete adult´s influence, as far as possible.Este trabajo está avalado por el Proyecto I+D+I, titulado “Competencias mediáticas de la ciudadanía en medios digitales emergentes (smartphones y tablets): prácticas innovadoras y estrategias educomunicativas en contextos múltiples” con clave EDU2015-64015-C3-1-R (MINECO/FEDER), financiado por el Fondo Europeo de Desarrollo Regional (FEDER) y Ministerio de Economía y Competitividad de España

Efecto de fotodegradacion producido por recubrimientos de ti o 2 y ti o 2 si o 2 obtenidos por sol gel

El método sol-gel es adecuado para la fabricación de sistemas binarios, con propiedades de interés a nivel industrial. Al adicionar SiO2 a un sistema de TiO2, las propiedades generales de este último se verán modificadas. En el caso de las propiedades fotocatalíticas, la adición de un 30% de SiO2, afecta significativamente el comportamiento de este sistema aún si se compara con otro al que se ha adicionado solo un 10% de este óxido, haciéndolo mas eficiente en los procesos de fotodegradación del azul de metileno, presente en una solución de 3.5mM. Este efecto se estudio, analizando el espectro de absorbancia de una solución de azul de metileno, concretamente a 665nm, donde esta presenta su máximo de absorbancia

Electronic structure of rectangular quantum dots

We study the ground state properties of rectangular quantum dots by using the spin-density-functional theory and quantum Monte Carlo methods. The dot geometry is determined by an infinite hard-wall potential to enable comparison to manufactured, rectangular-shaped quantum dots. We show that the electronic structure is very sensitive to the deformation, and at realistic sizes the non-interacting picture determines the general behavior. However, close to the degenerate points where Hund's rule applies, we find spin-density-wave-like solutions bracketing the partially polarized states. In the quasi-one-dimensional limit we find permanent charge-density waves, and at a sufficiently large deformation or low density, there are strongly localized stable states with a broken spin-symmetry.Comment: 8 pages, 9 figures, submitted to PR

Impact of global PTP1B deficiency on the gut barrier permeability during NASH in mice.

OBJECTIVE:Non-alcoholic steatohepatitis (NASH) is characterized by a robust pro-inflammatory component at both hepatic and systemic levels together with a disease-specific gut microbiome signature. Protein tyrosine phosphatase 1 B (PTP1B) plays distinct roles in non-immune and immune cells, in the latter inhibiting pro-inflammatory signaling cascades. In this study, we have explored the role of PTP1B in the composition of gut microbiota and gut barrier dynamics in methionine and choline-deficient (MCD) diet-induced NASH in mice. METHODS:Gut features and barrier permeability were characterized in wild-type (PTP1B WT) and PTP1B-deficient knockout (PTP1B KO) mice fed a chow or methionine/choline-deficient (MCD) diet for 4 weeks. The impact of inflammation was studied in intestinal epithelial and enteroendocrine cells. The secretion of GLP-1 was evaluated in primary colonic cultures and plasma of mice. RESULTS:We found that a shift in the gut microbiota shape, disruption of gut barrier function, higher levels of serum bile acids, and decreased circulating glucagon-like peptide (GLP)-1 are features during NASH. Surprisingly, despite the pro-inflammatory phenotype of global PTP1B-deficient mice, they were partly protected against the alterations in gut microbiota composition during NASH and presented better gut barrier integrity and less permeability under this pathological condition. These effects concurred with higher colonic mucosal inflammation, decreased serum bile acids, and protection against the decrease in circulating GLP-1 levels during NASH compared with their WT counterparts together with increased expression of GLP-2-sensitive genes in the gut. At the molecular level, stimulation of enteroendocrine STC-1 cells with a pro-inflammatory conditioned medium (CM) from lipopolysaccharide (LPS)-stimulated macrophages triggered pro-inflammatory signaling cascades that were further exacerbated by a PTP1B inhibitor. Likewise, the pro-inflammatory CM induced GLP-1 secretion in primary colonic cultures, an effect augmented by PTP1B inhibition. CONCLUSION:Altogether our results have unraveled a potential role of PTP1B in the gut-liver axis during NASH, likely mediated by increased sensitivity to GLPs, with potential therapeutic value

Bioaccumulation of total mercury in the earthworm Eisenia andrei

Earthworms are a major part of the total biomass of soil fauna and play a vital role in soil maintenance. They process large amounts of plant and soil material and can accumulate many pollutants that may be present in the soil. Earthworms have been explored as bioaccumulators for many heavy metal species such as Pb, Cu and Zn but limited information is available for mercury uptake and bioaccumulation in earth- worms and very few report on the factors that influence the kinetics of Hg uptake by earthworms. It is known however that the uptake of Hg is strongly influenced by the presence of organic matter, hence the influence of ligands are a major factor contribut - ing to the kinetics of mercury uptake in biosystems. In this work we have focused on the uptake of mercury by earthworms ( Eisenia andrei ) in the presence of humic acid (HA) under varying physical conditions of pH and temperature, done to assess the role of humic acid in the bioaccumulation of mercury by earthworms from soils. The study was conducted over a 5-day uptake period and all earthworm samples were analysed by direct mercury analysis. Mercury distribution profiles as a function of time, bioac- cumulation factors (BAFs), first order rate constants and body burden constants for mercury uptake under selected conditions of temperature, pH as well as via the dermal and gut route were evaluated in one comprehensive approach. The results showed that the uptake of Hg was influenced by pH, temperature and the presence of HA. Uptake of Hg 2 + was improved at low pH and temperature when the earthworms in soil were in contact with a saturating aqueous phase. The total amount of Hg 2 + uptake decreased from 75 to 48 % as a function of pH. For earthworms in dry soil, the uptake was strongly influenced by the presence of the ligand. Calculated BAF values ranged from 0.1 to 0.8. Mercury uptake typically followed first order kinetics with rate constants determined as 0.2 to 1 h ? 1 .Scopus 201

Plate fixation or intramedullary fixation of humeral shaft fractures: An updated meta-analysis

Background The optimal approach to operative treatment of humeral shaft fractures remains debatable. Previously published trials have been limited in size and have been inconclusive regarding important patient outcome variables following treatment with either intramedullary nails or plates. We conducted a meta-analysis of available trials comparing treatment of humeral shaft fractures

Effect of particle size, coupling agent and DDGS additions on Paulownia wood polypropylene composites

Studies aimed at improving the tensile, flexural, impact, thermal, and physical characteristics of wood–plastic composites composed of Paulownia wood flour derived from 36-month-old trees blended with polypropylene were conducted. Composites of 25% and 40% w/w of Paulownia wood were produced by twin-screw compounding and injection molding. Composites containing 0–10% by weight of maleated polypropylene were evaluated and an optimum maleated polypropylene concentration determined, i.e., 5%. The particle size distribution of Paulownia wood filler is shown to have an effect on the tensile and flexural properties of the composites. Novel combination composites of dried distiller’s grain with solubles mixed with Paulownia wood (up to 40% w/w) were produced and their properties evaluated. Depending on the composite tested, soaking composites for 872 h alters mechanical properties and causes weight gain