Hydrophobically modified polyelectrolytes as potential drugs reservoirs of n-alkyl-nitroimidazoles

Indexación: ScieloThe solubilization of three commercial drugs (ornindazole, metronidazole and tinidazole) and model compounds (N-alkyl-2-methyl-4-nitroimidazoles) on aggregates formed by anionic polyelectrolytes, carrying alkyl side chains of different length, have been investigated in aqueous solution at pH 3.0, 7.0 and 11.0. Potassium salts of poly(maleic acid-co-1-olefins), PA-nK2 with n ranging from 8 to 18, were used as micelle-forming polymers. The partition of these drugs between water and the hydrophobic microdomains provided by PA-nK2 was studied by the pseudo-phase model to determinate the distribution coefficient KS, and the standard free energy of transfer Δμºt. The results indicate that solubility of alkyl-nitroimidazoles on these polymer micelles depends moderately on the length of the alkyl chain, and therefore is mainly determined by the heterocyclic group. On the other hand, the solubilization of 1-hexyl-2-methyl-4-nitroimidazole increase with decreasing length of the side alkyl chain; i.e. KS follows the order PA-8K2 > PA-10K2 > PA-12K2 > PA-14K2 > PA-16K2 >PA-18K2.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072007000100014&nrm=is

Effect of disparity on the perception of motion-defined contours

We present three experiments that explored the effect of binocular disparity on the perception of contours defined by motion in a Spatiotemporal Boundary Formation. Depending on the disparity, the stimulus is perceived as an object that moves behind a holed surface (occluded configuration) or as a luminous transparency that moves over a surface that contains dots (occluding configuration). In all of the experiments, we used a Vernier task to assess the strength of contour perception. In the first experiment, we measured acuity as a function of disparity for a range of speeds and dot densities. The results showed that, despite the difference in the percepts, acuity was similar in both situations, replicating the dependence on speed and dot density demonstrated in previous studies. In the second experiment, the results showed that the dynamics of contour integration were identical for both occluded and occluding configurations. In the third experiment, we tested whether the mechanism of contour integration works independently from the interpretation of the scene. In this experiment, we inverted the disparity during stimulus presentation so that the stimulus switched between occluded and occluding configurations. The results showed that the switch of the depth order increased the threshold to the value obtained with a shorter presentation time. This might be produced by a resetting of the integration process driven by the change of depth order. The results are discussed within a conceptual model that places the process of contour integration in the context of the perception of objects in a Spatiotemporal Boundary Formation.Fil: Chambeaud, Javier G.. Universidad Nacional de Tucumán; ArgentinaFil: Martín, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; ArgentinaFil: Barraza, Jose Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; Argentin

Remaining Useful Life Estimation Based on Detection of Explosive Changes: Analysis of Bearing Vibration

The monitoring of condition variables for maintenance purposes is a growing trend amongst researchers and practitioners where decisions are based on degradation levels. The two approaches in Condition-Based Maintenance (CBM) are diagnosing the level of degradation (diagnostics) or predicting when a certain level of degradation will be reached (prognostics). Using diagnostics determines when it is necessary to perform maintenance, but it rarely allows for estimation of future degradation. In the second case, prognostics does allow for degradation and failure prediction, however, its major drawback lies in when to perform the analysis, and exactly what information should be used for predictions. This encumbrance is due to previous studies that have shown that degradation variable could undergo a change that misleads these calculations. This paper addresses the issue of identifying explosive changes in condition variables, using Control Charts, to determine when to perform a new model fitting in order to obtain more accurate Remaining Useful Life (RUL) estimations. The diagnostic-prognostic methodology allows for discarding pre-change observations to avoid contamination in condition prediction. In addition the performance of the integration methodology is compared against adaptive autoregressive (AR) models. Results show that using only the observations acquired after the out-of-control signal produces more accurate RUL estimations

Almidón de semilla de palta: Optimización del índice de blancura durante el proceso de extracción

Se evaluó la concentración de NaOH y tiempo de tratamiento de purificación en el índice de blancura y contenido de proteína del almidón aislado de semilla de palta. Para tal efecto, se empleó un Diseño Estadístico Central Compuesto Rotacional, que incluyeron 22 puntos factoriales + 2*2 puntos axiales y 5 repeticiones en el punto central, totalizando 13 ensayos experimentales. No se encontró diferencia significativa entre los tratamientos para contenido de proteína con valores entre 0,2% a 0,5%, a diferencia del índice de blancura, con valores superiores a 90, en el rango entre 90,86 (T1: 0,009 M; 104 min) a 95,33 (T2: 0,026 M; 104 min). El análisis de varianza del modelo cuadrático para índice de blancura fue significativo (p < 0,05), con valores de R2 y R2-ajustado de 83,74% y 80,21% respectivamente. Con la combinación óptima predicha de concentración de NaOH (0,0059 M) y tiempo de tratamiento de purificación (1 h con 13 min) se estimó el índice de blancura del almidón de 95,88%. Las respuestas encontradas en tres corridas experimentales en la validación del modelo cuadrático del índice de blancura (95,05±0,86%) se encontraron dentro del intervalo de confianza al 95%, con valores de desviación menores al 1%

SISTEMAS DE PRODUCCIÓN DE ACUACULTURA CON RECIRCULACIÓN DE AGUA PARA LA REGIÓN NORTE, NORESTE Y NOROESTE DE MÉXICO

Aquaculture is expanding and developing in practically all the regions of the world. The demand of the world-wide population by aquatic products is increasing, whereas the production from capture of fisheries has been being reduced, reaching many of them their maximum productive potential. As result of, sustaining fish supplies from capture fisheries it will not be possible to meet the growing global demand for aquatic food. Therefore, the aquaculture seems to have the potential to make a significant contribution to the production of these foods, in order to meet the growing population demand. Nevertheless, in order to accomplish it, the producer faces critical challenges. The development of these activities intensifies substantially, and requires to be diversified, producing new species and creating new systems and practices of production. The production systems of aquatic animals, particularly those based on technologies of water recirculation, appears to be an excellent alternative for producing, in regions of the North of Mexico, in where the water is scarce.Aquaculture, word wide population, aquatic food., Agribusiness,

Análisis de alternativas para la selección de plataformas de producción offshore. Aplicación en el Caribe Colombiano

The development of this article consists of the application of an analysis sequence which consists of four criteria that can be considered when developing an offshore oil field. First, a detailed study is made of the different types of platforms that can be used for the hydrocarbon production in deep and ultra-deep waters. Then, the selection criteria for each type of platform are developed depending on factors such as the characteristics of the reservoir, the technical requirements, and the meta-oceanic conditions of the site. Subsequently, it seeks to identify the basic facilities that the offshore facilities must-have, and a series of scenarios are proposed for the production of the fields taking as a reference the experiences of the Liwan field -1 located in deep waters of the South China Sea. The application of a scenario for the development of the Orca field is suggested, considering the needs of infrastructure, production systems, and facilities. In addition, the variables influenced by the meta-oceanic conditions of the area are analyzed. Thus, it analyzes all the variables that can drive the selection of a production platform in the northernmost seas of the country, specifically in the waters of the Colombian Caribbean Sea. © 2021 Universidad Industrial de Santander. All Rights Reserved

COVID-19 y salud reproductiva

El comportamiento de las enfermedades microbianas, ya sea por virus, bacterias o protozoos, y su respuesta inflamatoria son diferentes entre hombres y mujeres. Esta diferencia se hace notoria en la pandemia derivada por la enfermedad por coronavirus (COVID-19). Desde el reporte del primer caso de neumonía en diciembre de 2019, en Wuhan, China, la COVID-19 se ha diseminado a 212 países y territorios y, a la fecha, se ha confirmado más de 3,5 millones de casos, con una mortalidad mundial del 7%, lo que la convierte en una emergencia sanitaria internacional (1). Hasta ahora, en Colombia, hay más de 7000 casos confirmados, con más de 300 defunciones, de los cuales, más del 60% pertenecen al sexo masculino. Hasta el momento, la literatura científica disponible relacionada con la COVID-19 solo abarca ciertos aspectos de la salud reproductiva, tanto femenina como masculina, mientras se continúa recopilando más información que nos permita conocer y realizar un análisis más detallado de su impacto real en humanos durante el proceso infeccioso y las secuelas derivadas de este. Está confirmado que las condiciones médicas relacionadas con el síndrome metabólico y los estados de insulinorresistencia en hombres y mujeres agravan la presentación clínica y el pronóstico (2). La presente revisión pretende ilustrar los mecanismos relacionados con la respuesta inmunitaria diversa frente a las infecciones virales según el sexo del individuo, su compromiso gonadal y los efectos relacionados con la salud reproductiva masculina y femenina, que incluye la maternofetal y la posible transmisión vertical