Magnetic behavior of lamellar mnps3 and cdps3 composites with a paramagnetic manganese(iii) macrocyclic guest

Indexación: ScieloSix new composites derived from the intercalation of the MPS3 phases (M = MnII, CdIII) with the macrocyclic manganese(III) complex [MnL(H2O)2].NO3(H2O) (LH2 = Schiff base macrocyclic ligand derived from the condensation of 2-hydroxy-5-methy1-1,3-benzene-dicarbaldehyde and 1,2-diamine-benzene) were obtained by two different synthetic procedures: a conventional and a microwave assisted method. The composites [MnL]0.25K0.15Mn0.80 PS3(H2O)~1.0 (1), and [MnL]0.25K0.15Cd 0. 80PS3(H2O)~0.5 (2) were obtained by the conventional method, after stirring a suspension of the corresponding potassium precursor and the macrocyclic complex for two weeks, while [MnL]0.35K0.15Mn0.80 PS3(H2O)~1.0 (3) and [MnL]0.25K0.15Cd 0. 80PS3(H2O)~0.5 (4) after stirring for four weeks at room temperature. Using a microwave assisted reaction permitted to obtain in a shorter period of time as compared with the conventional method, composites [MnL]0.20K0.15Mn0.80 PS3(H2O)~1.0 (5) and [MnL]0.15K0.15Cd 0. 80PS3(H2O)~0.5 (6). All the M = MnII, MnIII composites show a bulk antiferromagnetic behavior. However, the spontaneous magnetization present at low temperature in the potassium precursor K0.40Mn0.80 PS3(H2O)~1.0 is observable in composite [MnL]0.20K0.15Mn0.80 PS3(H2O)~1.0 (5), while it is completely absent in composites [MnL]0.25K0.15Mn0.80 PS3(H2O)~1.0 (1) and [MnL]0.35K0.15Mn0.80 PS3(H2O)~1.0 (3). Keywords: Intercalation; MPS3 phases; MnIII macrocyclic complex; microwave assisted synthesis; magnetic properties

Permanent-magnet atom chips for the study of long, thin atom clouds

Atom-chip technology can be used to confine atoms tightly using permanently magnetised videotape along with external magnetic fields. The one-dimensional (1D) gas regime can be realised and studied by trapping the atoms in high-aspect-ratio traps in which the radial motion of the system is confined to zero-point oscillation

Gamma Dosimetry Using Some Dyes in Organic Solvents Solutions at 295 and 77 K

The aim of this work is to study the behavior under irradiation of different dyes (green malachite, methyl orange, red cresol, and bromothymol blue) in organic solvents (acetone and methanol) at different gamma doses and different temperatures to propose them as possible dosimeters for low-temperature applications. For this purpose, organic dissolutions were irradiated with gamma rays in the kiloGray (kGy) range at 77 and 295 K, and the color bleaching of the solutions was followed spectrophotometrically (UV-Vis range). The response curves at different temperatures show the linear range interval from 10 to 40 kGy with correlation coefficients of 0.999 and 0.998 for some systems. This is the main reason to continue carrying out studies that allow the proposal of these systems as chemical dosimeters

Comparación de pronósticos de caudales máximos con modelos ARIMA y redes neuronales artificiales

El presente estudio tuvo como principal objetivo comparar dos técnicas estadísticas de pronóstico  en el modelamiento del caudal máximo del río Huaura. La investigación fue de tipo aplicada y longitudinal porque se estudió el comportamiento de los caudales máximos del río Huaura a través del tiempo. Para cumplir con el objetivo se modeló la serie hidrológica mediante modelos ARIMA, donde 611 meses (90 %) de los datos se usó para ajuste del modelo y 68 meses (10 %), para  el pronóstico; y mediante redes neuronales artificiales autorregresivas (ARNN), donde 407 meses (60 %) de los datos se usó para entrenamiento, 204 meses (30 %), para prueba y 68 meses  (10 %), para reserva del modelo. Finalmente se encontró que el modelo ARNN es más eficiente que los modelos ARIMA para realizar pronósticos

Factores asociados al rendimiento académico de estudiantes de Ingeniería Estadística, Universidad Nacional de Trujillo, 2019

El objetivo de la investigación se centró en determinar factores asociados al rendimiento académico, para ello, se usó un diseño no experimental, transversal y descriptivo. Se utilizóla técnica de muestreo aleatorio irrestricto para determinar el tamaño de muestra, dando como  resultado 19 y 15 estudiantes de II Y IV ciclo respectivamente. Las técnicas estadísticas empleadas, utilizando el software R-Studio, fueron: la Selección de Clústeres para la clasificación de variables, donde se determinó 4 clúster denominados: Nivel educativo más alto entre los padres del estudiante, Factores Sociodemográficos, Medio de traslado a la universidad y Factores de distancia  y responsabilidad académica; y el Análisis Factorial de Correspondencias Múltiples determinándose el perfil de los estudiantes con promedio ponderado de mayor frecuencia, comprendido de 11 a 14, el cual se caracteriza por: su conformación de grupos que es heterogénea, sexo femenino, no presentan cursos rezagados, su medio de traslado es el transporte público, viven en Trujillo Metropolitano y tienen una edad mayor o igual a 20 años

Critical rotation of a harmonically trapped Bose gas

We study experimentally and theoretically a cold trapped Bose gas under critical rotation, i.e. with a rotation frequency close to the frequency of the radial confinement. We identify two regimes: the regime of explosion where the cloud expands to infinity in one direction, and the regime where the condensate spirals out of the trap as a rigid body. The former is realized for a dilute cloud, and the latter for a Bose-Einstein condensate with the interparticle interaction exceeding a critical value. This constitutes a novel system in which repulsive interactions help in maintaining particles together.Comment: 4 pages, 4 figures, submitted to PR

Recovery of early meteorological records from Extremadura region (SW Iberia): The ''CliPastExtrem'' (v1.0) database

In this work, we provide instrumental meteorological data recovered for the Extremadura region (interior SW Iberia), from 1826 to mid-20th century. Meteorological variables such as air temperature, atmospheric pressure, precipitation, wind direction and humidity, among others, were retrieved. In total, more than 750 000 instrumental data in 157 meteorological series belonging to 131 different locations throughout Extremadura were rescued. It must be noted that daily resolution data constitutes 80% of the database. This great effort of digitization and data collection has been carried out with the aim of contributing to a significant expansion of the length of the databases with meteorological information in this region. Therefore, this database will provide a better understanding of climate variability, trends and extreme events of the Extremadura region

Eastern Mediterranean water outflow during the Younger Dryas was twice that of the present day

Eastern Mediterranean deep-intermediate convection was highly sensitive to varying inputs of fresh water fluxes associated with increased rainfall during the African Humid period (15-6 kyr Before Present). Here we investigate changes in the water-outflow from the Eastern Mediterranean Sea since the last deglaciation using neodymium isotope ratios. Our results indicate enhanced outflow during the Younger Dryas, two times higher than present-day outflow and about three times higher than during the last Sapropel. We propose that the increased outflow into the western Mediterranean over the Younger Dryas was the result of the combined effect of 1) enhanced climate-driven convection in the Aegean Sea and 2) reduced convection of western deep water during this period. Our results provide solid evidence for an enhanced Younger Dryas westward flow of Eastern Mediterranean sourced waters in consonance with an intensification of Mediterranean water-outflow during a weakened state of the Atlantic circulatio

Continuous Matrix Product Ansatz for the One-Dimensional Bose Gas with Point Interaction

We study a matrix product representation of the Bethe ansatz state for the Lieb-Linger model describing the one-dimensional Bose gas with delta-function interaction. We first construct eigenstates of the discretized model in the form of matrix product states using the algebraic Bethe ansatz. Continuous matrix product states are then exactly obtained in the continuum limit with a finite number of particles. The factorizing $F$-matrices in the lattice model are indispensable for the continuous matrix product states and lead to a marked reduction from the original bosonic system with infinite degrees of freedom to the five-vertex model.Comment: 5 pages, 1 figur

Manejo de la cesación tabáquica entre residentes de cardiología de Iberoamérica

Si bien los cardiólogos asisten cotidianamente a pacientes que sufren daño por el tabaquismo, no se conoce el grado de formación que reciben sobre esta problemática durante su residencia. Debido a ello nos propusimos evaluar las preferencias y prácticas de los residentes de cardiología para la cesación tabáquica de los pacientes que asisten. Encuesta cerrada, prefijada, voluntaria y anónima entre médicos que realizaban la especialidad de cardiología en cinco países de Latinoamérica y España. Se encuestaron 716 residentes: un 62.4% de Argentina, un 19% de México, un 6.8% de España, un 6.7% de Chile, un 3.2% de Uruguay y un 1.9% de Paraguay. Con respecto a la importancia que asignaban a esta problemática (empleando una escala de 1-10), el 85.8% le asignó a esta pregunta una puntuación de 8 o mayor. Mientras el 80.5% de los participantes expresó dar consejo breve antitabáquico sistemáticamente, solamente un 27.7% empleaban terapia farmacológica con este fin. Entre quienes no empleaban terapia farmacológica, el 58.3% manifestó que el motivo era no encontrarse familiarizados con los tratamientos. El 62.9% de los encuestados dijo no haber recibido ningún tipo de formación en esta problemática. Aquellos residentes que recibieron algún tipo de formación manifestaron sentirse más preparados (p < 0.0001). Encontramos un bajo conocimiento sobre el tratamiento farmacológico y relativamente poca seguridad por parte de los residentes de cardiología para brindar asistencia en cesación tabáquica. Consideramos esencial incluir este tópico en la formación de los futuros cardiólogos a fin de lograr una prevención cardiovascular más integral