Development of electrochemical methods for determination of tramadol - analytical application to pharmaceutical dosage forms

A square-wave voltammetric (SWV) method and a flow injection analysis system with amperometric detection were developed for the determination of tramadol hydrochloride. The SWV method enables the determination of tramadol over the concentration range of 15-75 µM with a detection limit of 2.2 µM. Tramadol could be determined in concentrations between 9 and 50 µM at a sampling rate of 90 h-1, with a detection limit of 1.7 µM using the flow injection system. The electrochemical methods developed were successfully applied to the determination of tramadol in pharmaceutical dosage forms, without any pre-treatment of the samples. Recovery trials were performed to assess the accuracy of the results; the values were between 97 and 102% for both methods

Dominant microflora of picante cheese: Independent role upon proteolysis and lipolysis in model systems

Four species of bacteria (two species of enterococci, Enterococcus faecium and Enterococcus faecalis, and two species of lactobacilli, Lactobacillus plantarum and Lactobacillus paracasei) and three species of yeasts (Debaryomyces hansenii, Yarrowia lipolytica and Cryptococcus laurentii), previously isolated from Picante cheese were assayed for biochemical performance in proteolysis and lipolysis. In addition to the difference of the microbiological strains, the milk type (caprine or ovine), the ripening time (0 to 65 days) and the concentration of NaCl (0 to 14%(w/v)) have been deliberatly fixed in vitro curdled milk (previously prepared from heat-sterilized milk, coagulated with animal rennet and inoculated with each strain) and subject to 12 ºC. High proteolytic activity was demonstrated by Y. lipolytica and by all the other strains to a lesser extent; Y. lipolytica produced ca. 85% of WSN by 65 days of ripening whereas E. faecium, D. hansenii and C. laurentii produced levels of WSN ranging in 40-50%, and E. faecalis, L. plantarum and L. paracasei in 30- 40%. In terms of peptidolytic activity, measured by NPN contents and by release of free amino acids, once again Y. lipolytica presented the highest activity, followed by L. plantarum, L. paracasei, E. faecium and E. faecalis. Milk type, ripening time, and content of NaCl revealed to be statistically significant processing factors in terms of proteolysis; caprine milk, 65 days of ripening and lower contents of NaCl led to the highest values. The lipolytic activity, assessed by the release of butyric acid from tributyrin, was strong for Y. lipolytica and C. laurentii, whereas release of free fatty acids was observed at different rates for all strains under study. Ripening time proved to be a statistically significant factor for lipolysis, whereas milk type was not; lipolytic activities, measured as fat acidity index, were strongly affected by NaCl content and, as happened with release of free amino acids, the extent of fat hydrolysis was much more affected by the increase of NaCl from 0 to 7% than by its increase from 7% to 14%. Although it is not possible to directly compare results obtained in vitro using pure, single cultures with those obtained in loco using actual cheese, our results suggest that a mixed-strain starter for Picante cheese including L. plantarum, E. faecium (or E. faecalis) and D. hansenii (and/or Y. lipolytica) would be of potential interest.info:eu-repo/semantics/publishedVersio

Dominant microflora of Picante cheese: effects on proteolysis and lipolysis

Four species of bacteria (Enterococcus faecium and E. faecalis, Lactobacillus plantarum and L. paracasein and three species of yeasts (Debaryomyces hansenii, Yarrowia lipolytica and Cryptococcus laurentiU previously isolated from Picante cheese, were assayed for proteolysis and lipolysis. Milk type (caprine or ovine), ripening time (0 to 65 d) and concentration of NaCl (0 to 14 %(w/v)) have been assessed in terms of their effects upon in vitro curdled milk. Good evidence of proteolytic and peptidolytic activities was provided for Y. lipolytica, and at much lower levels for the other strains. Milk type, ripening time and content of NaCl appeared to be statistically significant processing factors in terms of proteolysis. Clear lipolytic activity was detected for Y. lipolytica, but release of free fatty acids to lesser extents was also observed for the other strains under study. Ripening time was statistically significant with regard to lipolysis but milk type was not. Lipolytic activities were strongly affected by presence of NaCl. According to experimental results, it is suggested that a mixed-strain starter for Picante cheese including L. plantarum, E. faecium (or E. faecalis,) and D. hansenii (and/or Y. lipolyticaj is of potential interest.info:eu-repo/semantics/publishedVersio

Organic acids produced by lactobacilli, enterococci and yeasts isolated from Picante cheese

Four species of bacteria (Enterococcus faecium and Enterococcus faecalis, Lactobacillus plantarum and Lactobacillus paracasei) and three species of yeasts (Debaryomyces hansenii, Yarrowia lipolytica and Cryptococcus laurentii), previously isolated from Picante cheese, were cultured in ovine and in caprine milk and assayed for sugar and organic acids metabolism for 6 days. The results indicated that both milk types can be coagulated by the four strains of lactic acid bacteria. Lb. paracasei led to a faster and greater reduction in pH. Production of lactic acid correlated to lactose degradation, and was highest for Lb. paracasei followed by E. faecium; citrate metabolism was apparent for E. faecalis and, to a lesser extent, for E. faecium, Lb. plantarum and Lb. paracasei. Relatively high contents of formic acid were found when inoculation was with Enterococcus and with Lb. plantarum

Role of dominant microflora of Picante cheese on proteolysis and lipolysis

Four species of bacteria (Enterococcus faecium and E. faecalis, Lactobacillus plantarum and Lb. paracasei) and three species of yeasts (Debaryomyces hansenii, Yarrowia lipolytica and Cryptococcus laurentii) isolated from Picante cheese were assayed for proteolytic and lipolytic activities. The milk type (caprine or ovine), the ripening time (0–65 d) and the concentration of NaCl (0–14% (w/v)) have been studied in terms of their effects upon in vitro curdled milk. Proteolytic and peptidolytic activities were demonstrated to be high for Y. lipolytica, and at much lower levels for the other strains. Milk type, ripening time and content of NaCl appeared to be statistically significant processing factors in terms of proteolysis. Clear lipolytic activity was detected for Y. lipolytica, but release of free fatty acids to lesser extents was observed for the other strains under study. Ripening time was statistically significant for lipolysis but milk type was not. Lipolytic activities were strongly affected by NaCl content and the extent of fat hydrolysis was affected by the increase of NaCl from 0 to 7% (w/v) more than by change from 7 to 14% (w/v). In view of the experimental results, a mixed-strain starter for Picante cheese including Lb. plantarum, E. faecium (or E. faecalis) and D. hansenii (and/or Y. lipolytica) is of potential interest

EL ESTUDIANTE UNIVERSITARIO Y SU PERCEPCIÓN DE LA VIDA UNIVERSITARIA: UNA APROXIMACIÓN A LAS REPRESENTACIONES SOCIALES DE LOS ESTUDIANTES DE PRIMER AÑO EN LAS CARRERAS DE INGENIERÍA

El presente trabajo se enmarca dentro del Proyecto de Investigación “Diseño de estrategias para la enseñanza del álgebra lineal y del cálculo en ingeniería con elementos de modelización. Articulación con el Nivel Medio” en ejecución en la Universidad Tecnológica Nacional, Facultad Regional Paraná, a través del cual se implementan dispositivos para mejorar el rendimiento académico de los estudiantes. En esta instancia se continúa con el trabajo de seguimiento comenzado en agosto de 2013 de los estudiantes aspirantes a las carreras de ingeniería, hoy día estudiantes de primer año, en relación con sus representaciones sociales en torno a lo que estudiar en la universidad implica. El objetivo inmediato en esta etapa de seguimiento es comparar las respuestas de los estudiantes antes de comenzar con los estudios universitarios con los obtenidos una vez finalizado el primer cuatrimestre del corriente año y así arrojar luz sobre aquellas representaciones que puedan estar obstaculizando su aprendizaje o haber sufrido modificaciones al encontrarse actuando en el contexto real. Las conclusiones a las que se arriba a través de este trabajo representan una instancia más en la que se intenta conocer en profundidad a los estudiantes que se incorporan a la vida universitaria desde una cultura que se encuentra distante de las demandas académicas inherentes a los estudios superiores. Se considera que esta ruta de acción es una manera posible para tender puentes entre los estudiantes, los docentes y el objeto de estudio y así maximizar el rendimiento académico de los primeros, redundando, a largo plazo, en una experiencia educativa positiva

Voltammetric quantification of fluoxetine: application to quality control and quality assurance processes

The oxidative behaviour of fluoxetine was studied at a glassy carbon electrode in various buffer systems and at different pH using cyclic, differential pulse and square wave voltammetry. A new square wave voltammetric method suitable for the quality control of fluoxetine in commercial formulations has been developed using a borate pH 9 buffer solution as supporting electrolyte. Under optimized conditions, a linear response was obtained in the range 10 to 16 μM with a detection limit of 1.0 μM. Validation parameters such as sensitivity, precision and accuracy were evaluated. The proposed method was successfully applied to the determination of fluoxetine in pharmaceutical formulations. The results were statistically compared with those obtained by the reference high-performance liquid chromatographic method. No significant differences were found between the methods

INGRESO UNIVERSITARIO: UNA APROXIMACIÓN A LAS REPRESENTACIONES SOCIALES DE LOS ASPIRANTES A LAS CARRERAS DE INGENIERÍA

La presente propuesta se enmarca dentro del Proyecto de Investigación “Diseño de estrategias para la enseñanza del álgebra lineal y del cálculo en ingeniería con elementos de modelización. Articulación con el Nivel Medio” en ejecución en la Universidad Tecnológica Nacional, Facultad Regional Paraná, a través del cual se implementan dispositivos para mejorar el rendimiento académico de los estudiantes. En esta instancia se exploran las representaciones sociales de los aspirantes a las carreras de ingeniería en relación con lo que significa para este grupo el ingreso universitario y las demandas inherentes a este nivel. Siguiendo los postulados de la teoría moscoviciana de las representaciones sociales se entiende esta noción como una forma de conocimiento adquirido en los grupos sociales en los que se desarrolla el individuo, proporcionándole un cúmulo de información, imágenes, opiniones y actitudes sobre distintos aspectos de la realidad cotidiana a través del cual le da sentido al mundo que lo rodea. Es por medio de estas representaciones que el individuo se desempeña en las distintas esferas de la vida. Esta investigación cuanti-cualitativa de base exploratoria se centra en la población de estudiantes que se incorpora a los cursos de Ingreso en el mes de agosto previo al inicio del primer año de estudios. Mediante encuestas en torno a ejes de indagación se busca información sobre los estudiantes y sus representaciones acerca del ingreso a la universidad. Sobre la base de los datos cuantitativos obtenidos se definen los tópicos a indagar en la segunda etapa, que consiste en la exploración de las representaciones en pequeños grupos de discusión focalizada. El análisis de las representaciones sociales aporta datos acerca del perfil de los aspirantes y del modo en que se posicionan frente al ingreso universitario, puesto que el mismo dependerá de la manera en que ellos perciben esa nueva experiencia

'Rocha’ Pear ripening under the 1-mcp evergreen effect: the impact of the auxin 1-naphthaleneacetic acid treatment

‘Rocha’ pear (Pyrus communis L. cv. Rocha), is a DOP cultivar from the West region of Portugal that is appreciated worldwide. Combined with controlled atmosphere storage, 1-methylcyclopropene (1-MCP) application, an antagonist of ethylene action, has been one of the most applied techniques to extend the storage of ‘Rocha’ pear. However, fruit industry is facing a problem resulting from 1-MCP application: it prevents the normal ripening of the fruit and affects the final quality at the consumer level. In this study, we exposed 1-MCP treated fruits to an auxin 1-naphthaleneacetic acid (1- NAA) solution (2 mM) and analyzed the efficacy in restoring the ripening of ‘Rocha’ pear. First, during the first 24 h, we determined the primary impact of 1-NAA on the expression of genes encoding ethylene receptors (PcETRs) and ethylene biosynthesis enzymes (PcACS and PcACO), combined with lipid peroxidation and reactive oxygen species. We also studied the effect of 1-NAA on ethylene production, respiration, and other ripening markers (firmness and sugars) across shelf life. Herein, the expression of PcACS1 and PcACS4 increased in 1-MCP fruit treated with 1- NAA compared to pear treated only with 1-MCP. Additionally, the expression of PcETR2 and PcETR5 was enhanced, revealing the potential of the 1-NAA treatment in inducing the production of new ethylene receptors. Time course physicochemical analysis revealed that fruit ripening was accelerated by 1- NAA treatment, as judged by ethylene evolution and respiration associated with softening. The 1-NAA treatment increased firmness loss (ca. 60%) and internal ethylene production (ca. 50%). Also, exogenous 1-NAA treatment increased 1- aminocyclopropane carboxylic acid (ca. 28%) and ACC oxidase activity (ca. 15%) corroborating the increased in gene expression. Our findings reveal that 1-NAA treatment may circumvent 1-MCP effect providing valuable information for ripening studies in pear.info:eu-repo/semantics/publishedVersio