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El Tratado de Libre Comercio Chile-China y su incidencia en las exportaciones chilenas
(Universidad de Chile, 2015-12)
La fuerte integración comercial que Chile ha llevado a cabo en los últimos veinticinco años se ha reflejado en sólidas cifras en esta materia, cuya tendencia ha llegado a influir de manera creciente sobre el comportamiento general de la economía...
Plan de Negocios para Desarrollar una Empresa de Inspección de Viviendas Orientada al Apoyo en las Decisiones de Compra y Venta por Parte de los Consumidores Chilenos
(Universidad de ChilePrograma Cybertesis, 2009)
El objetivo del presente trabajo de título consiste en un plan de negocios para desarrollar una empresa de inspección de viviendas orientada a apoyar las decisiones de compra y venta por parte de los consumidores chilenos. La idea consiste en...
Análisis de usuarios en aplicación móvil y economía del comportamiento en reportes de usuarios para mejorar el transporte público
(Universidad de Chile, 2020)
Transapp es una aplicación colaborativa móvil para smartphone fundada el 2016, en donde los usuarios pueden consultar tiempos de llegada de buses, emitir reportes acerca del estado de la infraestructura (ya sea buena o mala) y seguir sus viajes en...
Microextracción por sorción con disco rotatorio (RDSE) de fármacos antiinflamatorios no esteroidales (AINEs) desde muestras acuosas
(Universidad de Chile, 2015)
En las últimas dos décadas, los contaminantes orgánicos persistentes y los metales pesados eran el foco de interés y considerados como contaminantes prioritarios, por lo cual eran parte de programas de seguimiento intensivo. Hoy en día la emisión de...
Over the past two decades, persistent organic pollutants and heavy metals were the primary focus of environmental monitoring. Consequently, the decontamination policies applied by industrialized nations have resulted in drastic reductions of their environmental concentrations. Today, the “emerging” or “new” unregulated contaminants have become an environmental concern. These compounds are mainly derived from products used in large quantities in everyday life, such as pharmaceuticals from human use, veterinary products, personal care products, industrial plasticizers and additives. Emerging pollutants do not need to be persistent in the environment to cause negative effects because their high transformation and removal rates can be compensated by their continuous introduction into the environment. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the drugs most frequently detected in the environment. Due to its hydrophilicity and stability they tend to remain in water phase and are not completely eliminated by the wastewater treatment plants (WWTP), causing consequently pollution of surface waters. The extraction of six NSAIDs, including salicylic acid, ibuprofen, naproxen, ketoprofen, mefenamic acid and diclofenac from water samples by rotating-disk sorptive microextraction (RDSE) has been studied in this work. The extraction disk device was modified compared with the traditional disk configuration. In this case, the disk contains a central cavity which allows the incorporation of a powdered sorbent phase (Oasis ® HLB in this case). The phase in the cavity is covered with a filter paper and sealed with a Teflon ring to prevent phase leakage from the cavity. The analytes were extracted from water and pre-concentrated on the sorbent phase immobilized on the disc and after to reach the extraction equilibrium, the analytes were desorbed with solvent, derivatized and determined by gas chromatography-mass spectrometry (GC-MS). The optimal conditions for the extraction were the use of 60 mg of Oasis ® HLB as sorbent, a rotational disk velocity of 3000 rpm, pH 2, sample volume of 50 mL and extraction time of 90-100 min. Desorption of the compounds was performed with two additions of 5 mL of methanol (10 min each). The extract was evaporated to dryness with N2, re-dissolved with 0.5 mL of ethyl acetate and derivatized with 20 μL of MTBSTFA for one hour at 60 ° C. NSAIDs were determined by GC-MS in SIM mode. Two surrogate standards were included for quantification (fenoprop and meclofenamic acid) and internal standard (hexachlorobenzene). The recoveries ranged from 71 to 104% with relative standard derivations (RSD) between 2 and 8%. The detection limits ranged from 1 to 33 ngL-1, and the quantification limits ranged from 3 to 109 ngL-1. The described method was applied to the analysis of influents and effluents from wastewater treatment plants (WWTP) in Santiago, Chile. The concentrations of the detected drugs ranged from 1,5 to 13,4 μg L-1 and from 1,0 to 3,2 μg L-1 in the influents and effluents, respectively. The samples were extracted also by solid phase extraction (SPE) as comparative sample preparation technique. No significant differences were observed in the determined concentrations from most of the NSAIDs, indicating that RDSE is an alternative method from the preparation of water samples. Alternatively to the HLB phase, were studied molecularly imprinted polymers (MIP) as sorptive phase to analyze wastewater samples. The MIP was synthesized from the monomer 1-vinylimidazol (VI) together with the cross-linker divinylbenzene (DVB) using diphenylamine as the template molecule. In parallel, nonmolecularly imprinted polymer (NIP) was also synthesized for comparison. It was observed that under the same conditions, MIP extracted significantly more NSAIDs containing diphenylamine (or part of this molecule) in their structure than NIP. Higher significant differences between MIP and NIP were observed for diclofenac, mefenamic acid and paracetamol, clearly indicating the effect of the template on the extraction. Recoveries of the method were between 100-112%, with relative standard deviations of 5- 6%. The limits of detection were between 60 and 223 ngL-1. Water samples from a wastewater treatment plant (WWTP) of Santiago de Chile were found to contain concentrations of these acidic drugs between 1.6 and 4.3 μgL-1 and between 1.4 and 3.3 μgL- 1 in the influent and effluent, respectively. Finally, considering that in recent years the extraction techniques have been focused on achieving advances in automation, miniaturization and simplification of methodologies of extraction, a novel automatic sorptive microextraction approach combining sequential injection-based programmable flow with rotating disk sorptive extraction (RDSE) was proposed for the clean-up and concentration of low polarity organic species in urine samples (NSAIDs) and they were further determined by liquid chromatographic (LC) assays. The extracting phase consisted of octadecyl (C18). The thin-film extracting phase was demonstrated to be reusable for at least 15 consecutive extractions in urine without removing or changing the disk. The relative recoveries of the NSAIDs in urine ranged from 101 to 106% using a matrix-matched calibration curve, with extraction efficiencies of 30–38% using a dynamic regime, an enrichment factor of approximately 17 for 10 mL sample and relative standard deviations (RSD) between 3 and 6%. The detection limits of the in-line sample preparation method coupled to LC-UV detection ranged from 0.02 to 0.04 mg L−1. Using NSAID monitored in urine from individuals who received oral administration of ibuprofen and diclofenac, the automatic sample handling method was proven to be efficient for urine clean-up and the determination of acidic drugs at biologically relevant levels...
Over the past two decades, persistent organic pollutants and heavy metals were the primary focus of environmental monitoring. Consequently, the decontamination policies applied by industrialized nations have resulted in drastic reductions of their environmental concentrations. Today, the “emerging” or “new” unregulated contaminants have become an environmental concern. These compounds are mainly derived from products used in large quantities in everyday life, such as pharmaceuticals from human use, veterinary products, personal care products, industrial plasticizers and additives. Emerging pollutants do not need to be persistent in the environment to cause negative effects because their high transformation and removal rates can be compensated by their continuous introduction into the environment. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the drugs most frequently detected in the environment. Due to its hydrophilicity and stability they tend to remain in water phase and are not completely eliminated by the wastewater treatment plants (WWTP), causing consequently pollution of surface waters. The extraction of six NSAIDs, including salicylic acid, ibuprofen, naproxen, ketoprofen, mefenamic acid and diclofenac from water samples by rotating-disk sorptive microextraction (RDSE) has been studied in this work. The extraction disk device was modified compared with the traditional disk configuration. In this case, the disk contains a central cavity which allows the incorporation of a powdered sorbent phase (Oasis ® HLB in this case). The phase in the cavity is covered with a filter paper and sealed with a Teflon ring to prevent phase leakage from the cavity. The analytes were extracted from water and pre-concentrated on the sorbent phase immobilized on the disc and after to reach the extraction equilibrium, the analytes were desorbed with solvent, derivatized and determined by gas chromatography-mass spectrometry (GC-MS). The optimal conditions for the extraction were the use of 60 mg of Oasis ® HLB as sorbent, a rotational disk velocity of 3000 rpm, pH 2, sample volume of 50 mL and extraction time of 90-100 min. Desorption of the compounds was performed with two additions of 5 mL of methanol (10 min each). The extract was evaporated to dryness with N2, re-dissolved with 0.5 mL of ethyl acetate and derivatized with 20 μL of MTBSTFA for one hour at 60 ° C. NSAIDs were determined by GC-MS in SIM mode. Two surrogate standards were included for quantification (fenoprop and meclofenamic acid) and internal standard (hexachlorobenzene). The recoveries ranged from 71 to 104% with relative standard derivations (RSD) between 2 and 8%. The detection limits ranged from 1 to 33 ngL-1, and the quantification limits ranged from 3 to 109 ngL-1. The described method was applied to the analysis of influents and effluents from wastewater treatment plants (WWTP) in Santiago, Chile. The concentrations of the detected drugs ranged from 1,5 to 13,4 μg L-1 and from 1,0 to 3,2 μg L-1 in the influents and effluents, respectively. The samples were extracted also by solid phase extraction (SPE) as comparative sample preparation technique. No significant differences were observed in the determined concentrations from most of the NSAIDs, indicating that RDSE is an alternative method from the preparation of water samples. Alternatively to the HLB phase, were studied molecularly imprinted polymers (MIP) as sorptive phase to analyze wastewater samples. The MIP was synthesized from the monomer 1-vinylimidazol (VI) together with the cross-linker divinylbenzene (DVB) using diphenylamine as the template molecule. In parallel, nonmolecularly imprinted polymer (NIP) was also synthesized for comparison. It was observed that under the same conditions, MIP extracted significantly more NSAIDs containing diphenylamine (or part of this molecule) in their structure than NIP. Higher significant differences between MIP and NIP were observed for diclofenac, mefenamic acid and paracetamol, clearly indicating the effect of the template on the extraction. Recoveries of the method were between 100-112%, with relative standard deviations of 5- 6%. The limits of detection were between 60 and 223 ngL-1. Water samples from a wastewater treatment plant (WWTP) of Santiago de Chile were found to contain concentrations of these acidic drugs between 1.6 and 4.3 μgL-1 and between 1.4 and 3.3 μgL- 1 in the influent and effluent, respectively. Finally, considering that in recent years the extraction techniques have been focused on achieving advances in automation, miniaturization and simplification of methodologies of extraction, a novel automatic sorptive microextraction approach combining sequential injection-based programmable flow with rotating disk sorptive extraction (RDSE) was proposed for the clean-up and concentration of low polarity organic species in urine samples (NSAIDs) and they were further determined by liquid chromatographic (LC) assays. The extracting phase consisted of octadecyl (C18). The thin-film extracting phase was demonstrated to be reusable for at least 15 consecutive extractions in urine without removing or changing the disk. The relative recoveries of the NSAIDs in urine ranged from 101 to 106% using a matrix-matched calibration curve, with extraction efficiencies of 30–38% using a dynamic regime, an enrichment factor of approximately 17 for 10 mL sample and relative standard deviations (RSD) between 3 and 6%. The detection limits of the in-line sample preparation method coupled to LC-UV detection ranged from 0.02 to 0.04 mg L−1. Using NSAID monitored in urine from individuals who received oral administration of ibuprofen and diclofenac, the automatic sample handling method was proven to be efficient for urine clean-up and the determination of acidic drugs at biologically relevant levels...
Cambios hematológicos en aves y mamíferos de distinto requerimiento energético y su relación con la capacidad de difusión de oxígeno en el pulmón
(Universidad de Chile, 2011)
Los parámetros hematológicos y pulmonares parecen responder a las exigencias ambientales como la hipoxia y la alta altitud y a los requerimientos energéticos de la locomoción. En este trabajo se sometió a prueba la hipótesis que el hematocrito del...
Metodología multietapa para la planificación de la producción de largo plazoen minas a rajo abierto bajo incertidumbre geológica
(Universidad de Chile, 2017)
Esta tesis aborda el problema de planificación de la producción de largo plazo en minas de cielo abierto, considerando incertidumbre geológica. La solución de este problema define cómo y cuándo se extraerán las reservas mineras, generando una...
Algunos cambios que incorpora el T–MEC, en materia de inversiones extranjeras, en relación con lo previsto en el capítulo XI del TLCAN
(2019)
Penal, Sec-
ción Primera, nº 75/2018, de 12 septiembre 2018 ………………………………
El favor arbitri resultara determinante para la formalización judicial
cuando aparece clara la voluntad de sometimiento al arbitraje.
213-218
219...
participación en una empresa, que le permita al propietario participar en los ingresos o en las utilidades de la empresa; (f) una participación en una empresa que otorgue derecho al propietario para participar del haber social de esa empresa en una liquidación...
participación en una empresa, que le permita al propietario participar en los ingresos o en las utilidades de la empresa; (f) una participación en una empresa que otorgue derecho al propietario para participar del haber social de esa empresa en una liquidación...
Apatita magmática como monitor de la evolución de volátiles en intrusivos félsicos del área La Huifa-La Negra, Distrito el Teniente
(Universidad de ChilePrograma Cybertesis, 2009)
Este estudio evalúa el uso de la química de la apatita magmática (Ap) (incluida en fases anhidras (IAp) y como microfenocristales (MAp)) como monitor del comportamiento de H2O, Cl, F y S en los magmas que generaron los pórfidos dacíticos del Mioceno...
Significado que le asignan los profesores participantes del proyecto e-‐Pels al uso de las TIC en la enseñanza del Lenguaje
(Universidad de Chile, 2012-04-25)
reflexión y la
propuesta de soluciones a los retos que se nos presentan en términos de un acceso equitativo a
temas tan esenciales y relevantes como son el trabajo, la salud, la previsión y la educación - área
esta última, que motiva el presente texto – y...
); Plantea una relación dialéctica que bajo el doble proceso de interiorización de la exterioridad y, de exteriorización de la interioridad, busca poner de manifiesto los presupuestos tácitos y aparentemente inevitables que dan forma a la vida social. A...
); Plantea una relación dialéctica que bajo el doble proceso de interiorización de la exterioridad y, de exteriorización de la interioridad, busca poner de manifiesto los presupuestos tácitos y aparentemente inevitables que dan forma a la vida social. A...
La cultura de un internado de mujeres
(Universidad de Chile, 2015-10)
durante su proceso escolar. La pregunta de investigación ¿qué rasgos asume la cultura en un internado de mujeres? se contextualiza en la importancia de los internados como instituciones de doble condición, por una parte, de comunidad social y por otra en...