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Search Results: 1 - 10 of 23501 matches for " Fernando Ovalles "
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Flow analysis-hydride generation-gas phase derivative molecular absorption spectrophotometric determination of antimony in antileishmanial drugs
Gallignani, Máximo;Brunetto, María del Rosario;Ovalles, Fernando;
Química Nova , 2009, DOI: 10.1590/S0100-40422009000200013
Abstract: in the present work, the development of a method based on the coupling of flow analysis (fa), hydride generation (hg), and derivative molecular absorption spectrophotometry (d-eam) in gas phase (gp), is described in order to determine total antimony in antileishmanial products. second derivative order (d2224nm) of the absorption spectrum (190 - 300 nm) is utilized as measurement criterion. each one of the parameters involved in the development of the proposed method was examined and optimized. the utilization of the eam in gp as detection system in a continuous mode instead of atomic absorption spectrometry represents the great potential of the analytic proposal.
Metodología para la prospectiva científico técnica en la educación superior de los países del Convenio Andrés Bello
Ovalles,Omar;
Revista de Ciencias Sociales , 2008,
Abstract: this article contributes concrete ideas about the technological prospective that will make it possible to guide the integration and extension activities of latin american higher education institutions starting from n existing experiences, but also in terms of a new university transformation process that is advancing today in many of these institutions. some conceptual aspects are developed that are basic to being able to conceive a new university organizational structure from the viewpoint of integration and that takes into account the principal future tendencies of the technological prospective. some qualitative results are presented as examples of a participative prospective exercise that permitted detecting technological tendencies that would influence university transformation in the future.
Determination of atenolol in pharmaceutical dosages by Fourier transform infrared spectrometry (FTIR)
Ayala,Carlos; Brunetto,María del Rosario; Ovalles,Fernando; Gallignani,Máximo;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2009,
Abstract: in this work, a simple and rapid alternative method for determining atenolol in solid pharmaceutical dosages has been developed. the method is based on the dissolution, or extraction, of the active principle with chloroform and direct analysis of standard and sample solutions by ftir spectrometry. quantification of the analyte was carried out at the 1512 (principal band) and 1300 cm-1 bands, using as analytical signal the absorbance at 1512 and 1300 cm-1, respectively, corrected by mean appropriate baselines. the main figures of merit at the principal band (working range 0.1-1.0% (w/v), limit of detection (3 σ): 0.004% (w/v), limit of quantification (10 σ): 0.0125% (w/v), precision: 0.6% and sample throughput of 30 samples h-1) are attractive and really adequate for the proposed analysis. the accuracy of the method was certified by means comparative analysis of real samples using the official method described by the united stated of america pharmacopeia (usp). the method was satisfactorily applied to the determination of atenolol in a series of commercially available solid pharmaceutical samples. all the values obtained for the commercial samples were within the limit prescribed by the official pharmacopoeia.
Determinación de paraquat en orina utilizando un sistema de inyección en flujo continuo Determination of paraquat in urine samples by flow-injection analysis
José Rafael Luna,María Luisa Di Bernardo,María Ysabel García,Fernando Ovalles
Acta bioqu?-mica cl?-nica latinoamericana , 2008,
Abstract: El paraguat es un herbicida que pertenece al grupo de los biperidilos. Su determinación cuantitativa en orina es muy importante para diagnosticar la supervivencia de pacientes intoxicados. Muchos centros hospitalarios utilizan pruebas semicuantitativas para la determinación de paraquat en muestras biológicas. Sin embargo, éstas suelen carecer de precisión y exactitud. Por tanto, el desarrollo de métodos alternativos simples, exactos, precisos y accesibles podría resultar muy útil en instituciones hospitalarias. Sobre la base de estas consideraciones, se propone un método de análisis por inyección en flujo y detección espectrofotométrica para la determinación cuantitativa de paraquat en muestras de orina. La determinación se basa en la formación de un producto coloreado (600 nm) posterior a la reducción de paraquat con glucosa en un medio alcalino, mediante un sistema en línea. Bajo las condiciones óptimas de operación, la ley de Beer se cumple en el intervalo 1-50 μg mL-1 de paraquat con un coeficiente de correlación >0,999. La frecuencia de análisis fue de 12 h-1 con una desviación estándar relativa del 2,8% para una solución muestra que contiene 10 μg mL-1 de paraquat (n=3). El estudio de recuperación osciló entre 97,9 y 102,1%. El método analítico fue aplicado satisfactoriamente al análisis de muestras de dos pacientes intoxicados con paraquat. Paraguat is a herbicide beloging to the bipyridinium group.The quantitative determination of paraquat in urine of humans is very important to diagnose survival of intoxicated patients. Many hospitals use semi-quantitative tests for determining paraquat in biological samples. However, they often lack precision and accuracy. Therefore, the development of simple, precise, accurate and accessible alternative methods could be very useful in hospital institutions. Based on these considerations, a flow-injection spectrophotometric procedure is proposed for paraquat determination in urine samples. The determination is based on the formation of a coloured product (600 nm) after on-line reduction of paraquat with glucose in alkaline medium. Under optimal conditions of operation, Beer's law is obeyed in a concentration range of 1-50 μg mL-1 of paraquat with a correlation coefficient >0.999. The analytical frequency was 12 h-1 and the relative standard deviation was 2.8% for a sample solution containing 10 μg mL-1 paraquat (n=3). Recovery studies were between 97.9 and 102.1%. The analytical method was satisfactorily applied in the analyses of samples from two intoxicated patients.
Determinación de atenolol en productos farmacéuticos por espectrometría infrarroja con transformada de Fourier (FTIR) Determination of atenolol in pharmaceutical dosages by Fourier transform infrared spectrometry (FTIR)
Carlos Ayala,María del Rosario Brunetto,Fernando Ovalles,Máximo Gallignani
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2009,
Abstract: En este trabajo se desarrolla una propuesta metodológica alternativa, simple y rápida, para la determinación de atenolol en productos farmacéuticos. El método se basa en la disolución, o extracción, del principio activo con cloroformo y análisis directo de los estándares y muestras por espectrometría infrarroja con transformada de Fourier. La cuantificación del analito se llevó a cabo, en paralelo, en las bandas del analito centradas en 1512 (banda principal) y 1300 cm-1, utilizando como se al analítica la absorbancia a 1512 y 1300 cm-1, respectivamente, corregida mediante líneas de base apropiadas. Las figuras de mérito del método en la banda principal (intervalo de trabajo: 0,1-1,0% (p/v), límite de detección (3σ): 0,004% (p/v); límite de cuantificación (10 σ): 0,0125% (p/v), precisión: 0,6% y una frecuencia de análisis de 30 muestras h-1) resultan adecuadas para realizar el análisis propuesto. La exactitud del método se certificó mediante análisis comparativos de muestras reales con el método oficial descrito en la Farmacopea de los Estados Unidos de América (USP). Se analizaron, de forma satisfactoria, diversos productos farmacéuticos que se comercializan en el país. En todos los casos, la concentración encontrada está en el rango de tolerancia aceptado por la USP. In this work, a simple and rapid alternative method for determining atenolol in solid pharmaceutical dosages has been developed. The method is based on the dissolution, or extraction, of the active principle with chloroform and direct analysis of standard and sample solutions by FTIR spectrometry. Quantification of the analyte was carried out at the 1512 (principal band) and 1300 cm-1 bands, using as analytical signal the absorbance at 1512 and 1300 cm-1, respectively, corrected by mean appropriate baselines. The main figures of merit at the principal band (working range 0.1-1.0% (w/v), limit of detection (3 σ): 0.004% (w/v), limit of quantification (10 σ): 0.0125% (w/v), precision: 0.6% and sample throughput of 30 samples h-1) are attractive and really adequate for the proposed analysis. The accuracy of the method was certified by means comparative analysis of real samples using the official method described by the United Stated of America Pharmacopeia (USP). The method was satisfactorily applied to the determination of atenolol in a series of commercially available solid pharmaceutical samples. All the values obtained for the commercial samples were within the limit prescribed by the official pharmacopoeia.
Determinación de paraquat en orina utilizando un sistema de inyección en flujo continuo
Luna,José Rafael; Di Bernardo,María Luisa; García,María Ysabel; Ovalles,Fernando; Calderón,Laura;
Acta bioqu?-mica cl?-nica latinoamericana , 2008,
Abstract: paraguat is a herbicide beloging to the bipyridinium group.the quantitative determination of paraquat in urine of humans is very important to diagnose survival of intoxicated patients. many hospitals use semi-quantitative tests for determining paraquat in biological samples. however, they often lack precision and accuracy. therefore, the development of simple, precise, accurate and accessible alternative methods could be very useful in hospital institutions. based on these considerations, a flow-injection spectrophotometric procedure is proposed for paraquat determination in urine samples. the determination is based on the formation of a coloured product (600 nm) after on-line reduction of paraquat with glucose in alkaline medium. under optimal conditions of operation, beer's law is obeyed in a concentration range of 1-50 μg ml-1 of paraquat with a correlation coefficient >0.999. the analytical frequency was 12 h-1 and the relative standard deviation was 2.8% for a sample solution containing 10 μg ml-1 paraquat (n=3). recovery studies were between 97.9 and 102.1%. the analytical method was satisfactorily applied in the analyses of samples from two intoxicated patients.
ANáLISIS DE SISTEMAS ASFALTO-AGREGADO A PARTIR DE MEDICIONES DE ENERGíA SUPERFICIAL LIBRE
ALLEX E. ALVAREZ,EVELYN OVALLES
DYNA , 2012,
Abstract: La energía superficial libre (ESL) es una propiedad termodinámica fundamental de los materiales que puede ser empleada para cuantificar la calidad de la adhesión entre diversos materiales, la susceptibilidad de éstos a perder su adhesión por la presencia de agua en el sistema y la capacidad del recubrimiento de un material sobre otro con diferentes valores de ESL (i.e., humectabilidad). Estos principios son aplicables a diferentes materiales, incluidos los sistemas asfalto-agregado (i.e., mezclas asfálticas). El presente trabajo tiene como objetivo principal presentar un análisis, basado en mediciones de ESL de los materiales constitutivos de las mezclas asfálticas, mediante el cual se puede cuantificar la calidad de la adhesión, la susceptibilidad al da o por humedad y la calidad del recubrimiento del asfalto sobre el agregado en diversos sistemas asfalto-agregado. Las mediciones de ESL de asfaltos y agregados fueron realizadas en laboratorio a través del método de la Placa Wilhelmy y de la Máquina de Adsorción Universal (USD), respectivamente. Los materiales evaluados incluyeron asfaltos colombianos y agregados de origen colombiano y norteamericano. El análisis específico consistió en evaluar el efecto de procesos industriales de modificación y la adición de llenante mineral sobre la calidad de la adhesión, la susceptibilidad al da o por humedad y la humectabilidad de diversos sistemas asfalto-agregado. Los resultados sugieren que la medición de la ESL de asfaltos y agregados es una herramienta eficiente para evaluar la compatibilidad y el desempe o esperado de diversos sistemas asfalto-agregado, así como los cambios inducidos a nivel fundamental por diferentes procesos propios de la fabricación de mezclas asfálticas (e.g., adición de llenante mineral).
Seroprevalencia de anti-VHC en pacientes de la Unidad Regional de Inmunología Clínica del Estado Aragua. 2003-2004
Vicentellia,Rebeca; Rosalba Ovalles2,Vilma Lloverab; Apontea,Arauca;
Revista de la Sociedad Venezolana de Microbiología , 2005,
Abstract: abstract the anti-hcv seroprevalence was determined in 1615 serums of patients referred to the clinic inmunology regional unit of the state aragua, venezuela. the samples of serum were collected and analyzed by elisa test, following the manufacturer?s instruction. in 90 patients anti-hcv was detected, what represented a seroprevalence of 5,57% in the studied population. it prevailed lightly in males (53,33%) with regard to female (48,51%). the age average of these patients was 36,12 years old. most of the patients came from the girardot municipality (41,56%). only 11,24% of the serums of the patients with anti-hcv belonged to hospitalized people. we conclude that in the studied population the anti-hcv seroprevalence is very high
PARTIAL RESULTS OF POSSIBLE LATE ELECTROCARDIOGRAPHIC DISTURBANCES IN SCORPION-ENVENOMED PATIENTS IN EL LIMON DE QUIRIQUIRE, MONAGAS STATE, VENEZUELA
D. Acevedo,L. Padrino,V. Ovalles,M. Contreras
Journal of Venomous Animals and Toxins , 1999, DOI: 10.1590/s0104-79301999000100023
Abstract:
Implementación de un Filtro de Polarización basado en la Descomposición del Valor Singular (SVD)
Luque Rubén,Hurtado Nuri y Ovalles Asdrúbal
Physics , 2013,
Abstract: In this job we have introduced a filtered adaptive technique that allows highlighting selective seismic events according to its polarization. This technique consists in the implementation of a polarizing filter based on the Single Value Decomposition (SVD). The SVD have a great variety of application in the processing of signals and images, in this case a seismic reading is considered an image of the underground. With this technique, was achieved to make a reconstruction of the seismic image generated after the two first autoimages reproduce the polarization attributes (rectilinearity and planarity) of the moving particles, suppress the high frequency random sound, improve the signal-noise ratio and this way we were able to obtain a clear and coherent image of the associated seismic events to the primary energies of reflection.
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