Origin of orbital ferromagnetism and giant magnetic anisotropy at the nanoscale

The origin of orbital magnetism recently observed in different nanostructured films and particles is discussed as a consequence of spin-orbit coupling. It is shown that contact potentials induced at the thin film surface by broken symmetries, as domain boundaries in self-assembled monolayers, lead to orbital states that in some cases are of large radius. The component of the angular momentum normal to the surface can reach very high values that decrease the total energy by decreasing spin-orbit interaction energy. Intraorbital ferromagnetic spin correlations induce orbital momenta alignment. The estimated values of the magnetic moments per atom are in good agreement with the experimental observations in thiol capped gold films and nanoparticles

Nonlinear analysis of a simple model of temperature evolution in a satellite

We analyse a simple model of the heat transfer to and from a small satellite orbiting round a solar system planet. Our approach considers the satellite isothermal, with external heat input from the environment and from internal energy dissipation, and output to the environment as black-body radiation. The resulting nonlinear ordinary differential equation for the satellite's temperature is analysed by qualitative, perturbation and numerical methods, which show that the temperature approaches a periodic pattern (attracting limit cycle). This approach can occur in two ways, according to the values of the parameters: (i) a slow decay towards the limit cycle over a time longer than the period, or (ii) a fast decay towards the limit cycle over a time shorter than the period. In the first case, an exactly soluble average equation is valid. We discuss the consequences of our model for the thermal stability of satellites.Comment: 13 pages, 4 figures (5 EPS files

Magnetic properties of ZnO nanoparticles

We experimentally show that it is possible to induce room-temperature ferromagnetic-like behavior in ZnO nanoparticles without doping with magnetic impurities but simply inducing an alteration of their electronic configuration. Capping ZnO nanoparticles (similar to 10 nm size) with different organic molecules produces an alteration of their electronic configuration that depends on the particular molecule, as evidenced by photoluminescence and X-ray absorption spectroscopies and altering their magnetic properties that varies from diamagnetic to ferromagnetic-like behavior

Toward multitasking pharmacological COX-targeting agents: Non-steroidal anti-inflammatory prodrugs with antiproliferative effects

The antitumor activity of certain anti-inflammatory drugs is often attributed to an indirect effect based on the inhibition of COX enzymes. In the case of anti-inflammatory prodrugs, this property could be attributed to the parent molecules with mechanism other than COX inhibition, particularly through formulations capable of slowing down their metabolic conversion. In this work, a pilot docking study aimed at comparing the interaction of two prodrugs, nabumetone (NB) and its tricyclic analog 7-methoxy-2, 3-dihydro-1H-cyclopenta[b]naphthalen-1-one (MC), and their common active metabolite 6-methoxy-2-naphthylacetic acid (MNA) with the COX binding site, was carried out. Cytotoxicity, cytofluorimetry, and protein expression assays on prodrugs were also performed to assess their potential as antiproliferative agents that could help hypothesize an effective use as anticancer therapeutics. Encouraging results suggest that the studied compounds could act not only as precursors of the anti-inflammatory metabolite, but also as direct antiproliferative agents. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Nonlinear analysis of spacecraft thermal models

We study the differential equations of lumped-parameter models of spacecraft thermal control. Firstly, we consider a satellite model consisting of two isothermal parts (nodes): an outer part that absorbs heat from the environment as radiation of various types and radiates heat as a black-body, and an inner part that just dissipates heat at a constant rate. The resulting system of two nonlinear ordinary differential equations for the satellite's temperatures is analyzed with various methods, which prove that the temperatures approach a steady state if the heat input is constant, whereas they approach a limit cycle if it varies periodically. Secondly, we generalize those methods to study a many-node thermal model of a spacecraft: this model also has a stable steady state under constant heat inputs that becomes a limit cycle if the inputs vary periodically. Finally, we propose new numerical analyses of spacecraft thermal models based on our results, to complement the analyses normally carried out with commercial software packages.Comment: 29 pages, 4 figure

Quantitative considerations in medium energy ion scattering depth profiling analysis of nanolayers

The high depth resolution capability of medium energy ion scattering (MEIS) is becoming increasingly relevant to the characterisation of nanolayers in e.g. microelectronics. In this paper we examine the attainable quantitative accuracy of MEIS depth profiling. Transparent but reliable analytical calculations are used to illustrate what can ultimately be achieved for dilute impurities in a silicon matrix and the significant element-dependence of the depth scale, for instance, is illustrated this way. Furthermore, the signal intensity-to-concentration conversion and its dependence on the depth of scattering is addressed. Notably, deviations from the Rutherford scattering cross section due to screening effects resulting in a non-coulombic interaction potential and the reduction of the yield owing to neutralization of the exiting, backscattered H+ and He+ projectiles are evaluated. The former mainly affects the scattering off heavy target atoms while the latter is most severe for scattering off light target atoms and can be less accurately predicted. However, a pragmatic approach employing an extensive data set of measured ion fractions for both H+ and He+ ions scattered off a range of surfaces, allows its parameterization. This has enabled the combination of both effects, which provides essential information regarding the yield dependence both on the projectile energy and the mass of the scattering atom. Although, absolute quantification, especially when using He+, may not always be achievable, relative quantification in which the sum of all species in a layer add up to 100%, is generally possible. This conclusion is supported by the provision of some examples of MEIS derived depth profiles of nanolayers. Finally, the relative benefits of either using H+ or He+ ions are briefly considered

Opiniones de farmacéuticos que trabajan en un grupo de farmacias cuya diferenciación es la prestación de servicios de atención farmacéutica. El caso de Farmacias Trébol

Introducción: Nos pareció importante estudiar los métodos de trabajo de un grupo de farmacéuticos que ya tienen implantados los servicios de atención farmacéutica (AF) en sus farmacias, con el objetivo de explorar cómo actúan algunos profesionales a la hora de implantar y desarrollar dichos servicios. Método: Durante la segunda quincena de septiembre de 2009 se realizaron 20 entrevistas semiestructuradas a farmacéuticos del grupo Trébol en los distintos establecimientos y locales en Madrid, en las que participaron farmacéuticos que trabajan en las zonas de atención personalizada (ZAP) y otros que desarrollan su labor en el mostrador de las farmacias. Resultados: Algunos entrevistados creen que sólo en las farmacias grandes pueden desarrollarse servicios. Es mejor que la ZAP sea visible desde el exterior, para que llame la atención. Los mostradores individuales favorecen la privacidad. Trabajar con objetivos numéricos es uno de los elementos que facilitan la implantación de estos servicios, que a su vez se traducen en beneficios económicos. Los farmacéuticos entrevistados que trabajan en ZAP están satisfechos con el trabajo que realizan. La AF mejora la imagen de la farmacia en la que se ofrece, y aumenta las ventas farmacéuticas. Algunos afirman que el futuro pasa por convertir la farmacia en un centro de salud, con presencia de profesionales sanitarios de distintos campos, para que el paciente encuentre todos los servicios relacionados con la salud en un único establecimiento. Conclusiones: En Farmacias Trébol se entiende que la AF es una estrategia de negocio que permite la diferenciación respecto a las demás farmacias, es rentable y fideliza a los pacientes

Opiniones de farmacéuticos que trabajan en un grupo de farmacias cuya diferenciación es la prestación de servicios de atención farmacéutica. El caso de Farmacias Trébol

Introducción: Nos pareció importante estudiar los métodos de trabajo de un grupo de farmacéuticos que ya tienen implantados los servicios de atención farmacéutica (AF) en sus farmacias, con el objetivo de explorar cómo actúan algunos profesionales a la hora de implantar y desarrollar dichos servicios. Método: Durante la segunda quincena de septiembre de 2009 se realizaron 20 entrevistas semiestructuradas a farmacéuticos del grupo Trébol en los distintos establecimientos y locales en Madrid, en las que participaron farmacéuticos que trabajan en las zonas de atención personalizada (ZAP) y otros que desarrollan su labor en el mostrador de las farmacias. Resultados: Algunos entrevistados creen que sólo en las farmacias grandes pueden desarrollarse servicios. Es mejor que la ZAP sea visible desde el exterior, para que llame la atención. Los mostradores individuales favorecen la privacidad. Trabajar con objetivos numéricos es uno de los elementos que facilitan la implantación de estos servicios, que a su vez se traducen en beneficios económicos. Los farmacéuticos entrevistados que trabajan en ZAP están satisfechos con el trabajo que realizan. La AF mejora la imagen de la farmacia en la que se ofrece, y aumenta las ventas farmacéuticas. Algunos afirman que el futuro pasa por convertir la farmacia en un centro de salud, con presencia de profesionales sanitarios de distintos campos, para que el paciente encuentre todos los servicios relacionados con la salud en un único establecimiento. Conclusiones: En Farmacias Trébol se entiende que la AF es una estrategia de negocio que permite la diferenciación respecto a las demás farmacias, es rentable y fideliza a los pacientes