Electron gas at the interface between two antiferromagnetic insulating manganites

We study theoretically the magnetic and electric properties of the interface between two antiferromagnetic and insulating manganites: La0.5Ca0.5MnO3, a strong correlated insulator, and CaMnO3, a band-insulator. We find that a ferromagnetic and metallic electron gas is formed at the interface between the two layers. We confirm the metallic character of the interface by calculating the in-plane conductance. The possibility of increasing the electron gas density by selective doping is also discussed.Comment: 6 pages, including 9 figure

Phase Diagram and Incommensurate Phases in Undoped Manganites

We study the existence of incommensurate phases in the phase diagram of the two orbital double exchange model coupled with Jahn-Teller phonons and with superexchange interactions. In agreement with experimental results, we find that undoped manganites $RMnO_3$ ($R$ being some rare earth element) show temperature induced commensurate-incommensurate phase transitions. In the incommensurate phase the magnetic wave vector varies with temperature. The incommensurate phase arises from the competition between the short range antiferromagnetic superexchange interaction and the long range ferromagnetic double exchange interaction

Application of SERS to the determination of butylated hydroxyanisole in edible and essential oils

Surface-enhanced Raman scattering (SERS) has been applied to the determination of the antioxidant butylated hydroxyanisole (BHA), commonly used in fatty foods and oils to prevent their oxidation. The use of SERS Raman microscopy with an inexpensive homemade silver substrate allowed the direct determination of BHA in oils without any sample handling. Several edible and essential oils (used as flavorings) have been considered for this purpose. The experimental conditions, the peculiarities of each type of oil, and the characteristics of silver substrate, including scanning electron microscopy (SEM) analysis, are shown and discussed

Disorder-Induced First Order Transition and Curie Temperature Lowering in Ferromagnatic Manganites

We study the effect that size disorder in the cations surrounding manganese ions has on the magnetic properties of manganites. This disorder is mimic with a proper distribution of spatially disordered Manganese energies. Both, the Curie temperature and the order of the transition are strongly affected by disorder. For moderate disorder the Curie temperature decreases linearly with the the variance of the distribution of the manganese site energies, and for a disorder comparable to that present in real materials the transition becomes first order. Our results provide a theoretical framework to understand disorder effects on the magnetic behavior of manganites.Comment: 4 pages, three figures include

Evaluation of new antimicrobial materials incorporating ethyl lauroyl arginate or silver into different matrices, and their safety in use as potential packaging

A big challenge for today’s industry is antimicrobial preservation and the safety of food. An effective solution to this problem can be a modern invention such as antimicrobial packaging. In the presented research the antimicrobial activity of two new active films incorporating silver, as IONPURE IPL, and ethyl lauroyl arginate (LAE) were evaluated, by employing a low-density polyethylene (LDPE) matrix and a biofilm material, respectively. Additionally, LAE was also incorporated into polystyrene (PS) pads by two different methods: by spraying and by immersion of the PS pads into an aqueous LAE solution. LDPE films containing silver did not show any antimicrobial activity against Escherichia coli and Aspergillus flavus, whereas the biofilm containing LAE reduced the growth of Salmonella enterica but did not inhibit Aspergillus flavus. The active PS pads, both sprayed and immersed in LAE solution, also showed antimicrobial activity, causing a reduction of 99.99% of Pseudomonas putida growth. Thermal treatment at 180¿C for 6 and 15 min did not modify the antimicrobial activity of LAE against Salmonella enterica. Moreover, inductively coupled plasma-mass spectrometry (ICP-MS) analysis was performed to check the migration of silver from developed material intended for food packaging applications into food simulant

Utilidad de la dermatoscopia en el diagnóstico de la escabiosis

Presentamos el caso de una paciente de 17 años de edad, previamente sana, que consultó por un cuadro de tres semanas de evolución consistente en prurito intenso de predominio nocturno y lesiones cutáneas, sin otra sintomatología sistémica acompañante. En tratamiento con bilastina 20 mg, no había presentado mejoría. La paciente negaba la existencia de convivientes cercanos afectos por los mismos síntomas. A la exploración física presentaba lesiones en forma de pápulas eritematosas milimétricas, alguna de ellas excoriada, a nivel de huecos interdigitales y zona periumbilical. Además, se apreciaba alguna lesión con morfología lineal, ligeramente descamativa, así como vesículas de contenido claro asociadas a las anteriores (fig. 1a). El examen con dermatoscopia de luz polarizada mostró los siguientes hallazgos (fig. 1b): sobre un fondo de eritema, la presencia de estructuras circulares blanco-amarillentas correspondientes a vesículas acarinas, así como una estructura lineal descamativa de morfología ondulada, en cuyo extremo se podía identificar un triángulo marrón..

Aplicación de las técnicas de suavizado en la variación negativa contingente (CNV)

El presente trabajo recoge de forma breve laproblemática de la estimación de la serial en series temporales de datos obtenidos en registros ERP. Se centra en aquellos componentes de frecuencia mis baja, como es el caso de la CNV: Sepropone la utilización alternativa de las técnicas de suavizado del Análisis Exploratorio de Datos (EDA), para mejorar la estimación obtenida, en comparación con la técnica del promediado simple de diferentes ensayos

Líneas cutáneas prominentes: un nuevo criterio de sospecha en lesiones melanocíticas

Presentación del caso Una mujer de 64 años de edad, con daño actínico severo,consultó por una lesión pigmentada de reciente aparición enla cara externa de la pierna izquierda. La exploración clínica reveló que se trataba de una mácula pigmentada irregularde 7mm de diámetro mayor, de aspecto lentiginoso, en uncontexto de intenso fotodaño con la presencia de múltipleslentigos solares en el área cutánea circundante (fig. 1). Comentario Con la dermatoscopia de luz polarizada se apreciaba un discreto retículo pigmentado irregular, áreas de color marrón claro sin estructura, áreas hipopigmentadas y escasos puntos de distribución irregular. Llamaba la atención la presencia de unas líneas o surcos cutáneos prominentes, más claros que el resto de la lesión y que se entrecruzaban entre ellos,interrumpiendo las demás estructuras. Además, se podían observar vasos puntiformes en las zonas hipopigmentadas, más evidentes que en la piel circundante (fig. 2). Teniendo en cuenta el contexto clínico (se trataba de una lesión pigmentada plana de reciente aparición en una paciente con intenso daño solar) y los hallazgos dermatoscópicos, se extirpó la lesión. El estudio anatomopatológico fue de un melanoma maligno in situ, con un patrón de crecimiento lentiginoso. ..

Competition between covalent bonding and charge transfer at complex-oxide interfaces

Here we study the electronic properties of cuprate/manganite interfaces. By means of atomic resolution electron microscopy and spectroscopy, we produce a subnanometer scale map of the transition metal oxidation state profile across the interface between the high $T_c$ superconductor YBa$_2$Cu$_3$O$_{7-\delta}$ and the colossal magnetoresistance compound (La,Ca)MnO$_3$. A net transfer of electrons from manganite to cuprate with a peculiar non-monotonic charge profile is observed. Model calculations rationalize the profile in terms of the competition between standard charge transfer tendencies (due to band mismatch), strong chemical bonding effects across the interface, and Cu substitution into the Mn lattice, with different characteristic length scales.Comment: 11+7 pages, 3+2 figure