Advanced Search
Now showing items 4911-4920 of 4980
Real estate consultants
(Universidad de Chile, 2014-07)
la Ley 19.537 sobre Copropiedad
Inmobiliaria o “Ley de Condominios”. Si bien un 23% de la población en Chile se encuentra
viviendo bajo este régimen al año 2013, el país tiene poca experiencia en la materia (Fuente
CGAI), siendo ésta es una de las...
. Fuente: Colegio de Gestión y Administración Inmobiliaria, 2009 3.6.1. Posicionamiento relativo En general, la percepción de la sociedad sobre las administraciones es que son poco profesionales, y especialmente en el área residencial se suma la...
. Fuente: Colegio de Gestión y Administración Inmobiliaria, 2009 3.6.1. Posicionamiento relativo En general, la percepción de la sociedad sobre las administraciones es que son poco profesionales, y especialmente en el área residencial se suma la...
Optimización de la configuración y calendarización del proceso por lotes de planta elaboradora de producto biotecnológico
(Universidad de Chile, 2020)
parte, la necesidad vital de recursos, rutas de reacción alternativas, procesos
químicos industriales amigables con el medio ambiente y económicamente viables, se ha
convertido en una realidad ubicua [1]. En este sentido, el proceso basado en...
. Finalmente, el grado de certeza sobre el valor de los parámetros críticos del proceso podrá ser determinístico o estocástico [4]. 2.2. El problema de la calendarización Los procesos por lotes se diferencian de los procesos continuos principalmente en que el...
. Finalmente, el grado de certeza sobre el valor de los parámetros críticos del proceso podrá ser determinístico o estocástico [4]. 2.2. El problema de la calendarización Los procesos por lotes se diferencian de los procesos continuos principalmente en que el...
Diseño de un procedimiento para la separación de los iones tierras raras lantano(III), cerio(III), praseodimio(III) y neodimio(III) mediante membranas líquidas emulsificadas utilizando como agentes transportadores extractantes organofosforados
(Universidad de Chile, 2013)
membranas líquidas emulsificadas, utilizando extractantes organofosforados como agentes transportadores. Se busca que en cada etapa se provoque la separación de cada elemento, favoreciendo su extracción hacia la fase membrana y/o hacia la fase acuosa interna...
This Thesis proposes a separation route for the lanthanide metal ions, lanthanum (III), cerium (III), praseodymium (III) and neodymium (III), from a sample treat simulates the approximate concentrations of a leaching solution of bastnaesite, by means of Emulsified Liquid Membranes using organophosphorus extractants as transport agents. The purpose is to achieve the separation of each element by their extraction into the membrane phase and/or to the internal aqueous phase or eventually remained mostly in the raffinate. By means of a kinetic study of extraction for all lanthanide elements contained into the feed aqueous phase it was determined that the optimal time for extracting and transferring the elements is 15 minutes, because from this time the maximum extraction and transfer percentages are achieved. Firstly, we conducted a study of extraction behavior of all possible pairs of lanthanide elements, formed between lanthanum, cerium, praseodymium and neodymium, in order to propose a possible route of separation for them by means of Emulsified Liquid Membrane methodology. In this study, the concentration of the CYANEX 272 carrier was varied between 1.25 and 5 mM, bufferized at pH 4 with 3-chloropropionic acid 0.2 M. Under these working conditions it was determined that after three stages of contact an aqueous solution rich in lanthanum having a purity of 86.5% and a yield of 27.9% is obtained. However, the analysis of the extraction through the distribution coefficients, obtained from the extraction study of lanthanide pairs, indicated that a lanthanum solution almost purity of 100% with a yield of 49.1 is obtained. These differences in results are due to that the extraction steps projection requires readjustment of operational conditions on the raffinate to the initial conditions on the feed solution. Secondly, a solution containing cerium, praseodymium and neodymium, based on the assumption that the lanthanum was completely removed, was used as feed solution. Due to in the previous experimental conditions it was not possible to separate one of these three elements it was decided to add hydrogen peroxide as oxidizing agent to the feed solution, in order to cause the change of the oxidation state in the cerium element from 3+ to 4+. Additionally, this modification considered the decreasing of the initial pH value from 4 to 2.5, since it is not possible to have the Ce4+ ions in aqueous solution at pH higher than 3, because it is precipitated as hydroxide. Furthermore, it is known that the extraction of the Ce4+ ions is low and those of praseodymium and neodymium 3+ ions are deficient with the extractant CYANEX 272. For this reason, the extractant D2EHPA from the same organophosphorus family but of higher strength binder, was chosen. At these working conditions, by a projection of this result, is necessary to make two contact steps of the feed solution containing Ce4+, Pr3+ and Nd3+ with a primary emulsion for obtaining a cerium-rich raffinate, with a purity around 100% and a 33.3% yield. Once the separations of lanthanum and cerium from solutions containing the four lanthanide elements are achieved, the study was focused on the separation of the praseodymium/neodymium pair of elements using two alternatives: one of them include complexing or masking agents contained in aqueous solution and, the other, one synergistic agent in the membrane phase. The obtained results indicated that the addition of complexing agents, such as I-, SCN-, citrate and imidazole have not significant effect on the separation of the two elements, while the inclusion of TBP and TOPO as synergistic agents generated, in the best cases, a separation coefficient in the internal aqueous phase for neodymium/praseodymium of 0.84, when 100 mM of TBP is used. By means of a analysis of this separation coefficient, was established that it is necessary to make five contact steps of the feed solution with a primary emulsion, where the praseodymium is concentrated in the inner aqueous phase and neodymium remains in the organic phase, for giving a rich-praseodymium aqueous solution having near 100% purity and a 5.6% yield. Although in some cases the yields are low, the capacity for waste reprocessing is easy to perform in a simple and direct way. For this reason the method has great potential for application in the separation of these lanthanide elements by means of emulsified liquid membranes using the organophosphorus family as carrier...
This Thesis proposes a separation route for the lanthanide metal ions, lanthanum (III), cerium (III), praseodymium (III) and neodymium (III), from a sample treat simulates the approximate concentrations of a leaching solution of bastnaesite, by means of Emulsified Liquid Membranes using organophosphorus extractants as transport agents. The purpose is to achieve the separation of each element by their extraction into the membrane phase and/or to the internal aqueous phase or eventually remained mostly in the raffinate. By means of a kinetic study of extraction for all lanthanide elements contained into the feed aqueous phase it was determined that the optimal time for extracting and transferring the elements is 15 minutes, because from this time the maximum extraction and transfer percentages are achieved. Firstly, we conducted a study of extraction behavior of all possible pairs of lanthanide elements, formed between lanthanum, cerium, praseodymium and neodymium, in order to propose a possible route of separation for them by means of Emulsified Liquid Membrane methodology. In this study, the concentration of the CYANEX 272 carrier was varied between 1.25 and 5 mM, bufferized at pH 4 with 3-chloropropionic acid 0.2 M. Under these working conditions it was determined that after three stages of contact an aqueous solution rich in lanthanum having a purity of 86.5% and a yield of 27.9% is obtained. However, the analysis of the extraction through the distribution coefficients, obtained from the extraction study of lanthanide pairs, indicated that a lanthanum solution almost purity of 100% with a yield of 49.1 is obtained. These differences in results are due to that the extraction steps projection requires readjustment of operational conditions on the raffinate to the initial conditions on the feed solution. Secondly, a solution containing cerium, praseodymium and neodymium, based on the assumption that the lanthanum was completely removed, was used as feed solution. Due to in the previous experimental conditions it was not possible to separate one of these three elements it was decided to add hydrogen peroxide as oxidizing agent to the feed solution, in order to cause the change of the oxidation state in the cerium element from 3+ to 4+. Additionally, this modification considered the decreasing of the initial pH value from 4 to 2.5, since it is not possible to have the Ce4+ ions in aqueous solution at pH higher than 3, because it is precipitated as hydroxide. Furthermore, it is known that the extraction of the Ce4+ ions is low and those of praseodymium and neodymium 3+ ions are deficient with the extractant CYANEX 272. For this reason, the extractant D2EHPA from the same organophosphorus family but of higher strength binder, was chosen. At these working conditions, by a projection of this result, is necessary to make two contact steps of the feed solution containing Ce4+, Pr3+ and Nd3+ with a primary emulsion for obtaining a cerium-rich raffinate, with a purity around 100% and a 33.3% yield. Once the separations of lanthanum and cerium from solutions containing the four lanthanide elements are achieved, the study was focused on the separation of the praseodymium/neodymium pair of elements using two alternatives: one of them include complexing or masking agents contained in aqueous solution and, the other, one synergistic agent in the membrane phase. The obtained results indicated that the addition of complexing agents, such as I-, SCN-, citrate and imidazole have not significant effect on the separation of the two elements, while the inclusion of TBP and TOPO as synergistic agents generated, in the best cases, a separation coefficient in the internal aqueous phase for neodymium/praseodymium of 0.84, when 100 mM of TBP is used. By means of a analysis of this separation coefficient, was established that it is necessary to make five contact steps of the feed solution with a primary emulsion, where the praseodymium is concentrated in the inner aqueous phase and neodymium remains in the organic phase, for giving a rich-praseodymium aqueous solution having near 100% purity and a 5.6% yield. Although in some cases the yields are low, the capacity for waste reprocessing is easy to perform in a simple and direct way. For this reason the method has great potential for application in the separation of these lanthanide elements by means of emulsified liquid membranes using the organophosphorus family as carrier...
Efectos de expansión de capacidad vial en congestión y su interacción con otras políticas urbanas
(Universidad de Chile, 2016)
investigacio´n ma´s relevantes
que se desprenden de esta tesis.
3
Cap´ıtulo 2
Revisio´n Bibliogra´fica
La literatura existente sobre los efectos que puede llegar a tener una inversio´n de
capacidad vial en un sistema de transporte data de Downs [1962] y Thomson...
congestio´n. El objetivo principal de esta tesis es obtener conclusiones que permitan entregar recomendaciones sobre pol´ıticas de transporte. Para esto, se utiliza un modelo donde la demanda de viajes totales es sensible a cam- bios en los precios y tiempos...
congestio´n. El objetivo principal de esta tesis es obtener conclusiones que permitan entregar recomendaciones sobre pol´ıticas de transporte. Para esto, se utiliza un modelo donde la demanda de viajes totales es sensible a cam- bios en los precios y tiempos...
Planificación de sistemas de transporte rápido con congestión
(Universidad de Chile, 2013)
adecuadas, ha producido un aumento en la congestión vehicular. Por este motivo varias son las ciudades que han planificado o construido redes de transporte rápido, tales como metro o sistemas ferroviarios ligeros. Si bien la sola construcción de estas redes...
Metodología para caracterización de génesis y distribución de elementos traza en depósitos de relaves chilenos
(Universidad de Chile, 2018)
Chile es un país minero, destacado por ser uno de los mayores productores de Cu en el mundo, los cuales provienen de yacimientos explotados principalmente en la 2°, 3° y 4° Región. Sin embargo, como consecuencia de esta explotación del mineral se...
Petrología y geoquímica de lavas recientes, al sureste del campo geotermal del Tatio
(Universidad de Chile, 2014)
sobre los 4000 m.s.n.m. al sureste del campo geotermal del Tatio, en la Zona Volcánica Central (ZVC), Andes. La evolución de ellos toma lugar en el Pleistoceno Inferior-Superior, con una actividad predominantemente efusiva y litología caracterizada por...
Explorando la interacción entre el péptido señal de translocación reticular y el translocón Sec61 mediante espectroscopía de fuerza a nivel de molécula individual
(Universidad de Chile, 2020)
mutación Ala13Glu puede ser multifactorial. Una menor distancia al estado de transición implica una mayor rigidez de la interacción, mientras que una menor adhesividad de las esferas apunta a un efecto negativo sobre la asociación con el translocón, lo que...
Sec61 is a protein transporter channel, known as the translocon, found in the membrane of the endoplasmic reticulum in eukaryotes. Its function is to allow the passage of proteins from the cytosol to the reticular lumen in a process known as translocation, which is the first step in the protein secretory pathway. In humans, about 38% of the proteins synthesized by the cell translocate to the reticular lumen. This is because they possess an amino acid sequence, at its N-terminus, known as a “signal peptide”, which plays a role of recruiting the protein to the reticulum membrane and, later, of interaction with the translocon. This last function represents the first step in the translocation process, making it particularly interesting to study. The signal peptide has a poorly conserved sequence between proteins, however, three common regions are distinguished in all of them: an N-terminal region of positively charged residues (n region), a hydrophobic region in the form of an α helix (h region) and a C-terminal region of short-chain polar residues (c region). The h region is essential for the translocation process, as mutations in hydrophobic residues in this sequence dramatically decrease translocation and secretion rates. The h region of the signal peptide acts by inserting it into a "lateral gate" of the Sec61 channel, causing a conformational change that opens the pore and leaves the translocon in an active conformation. To study the translocation process, the S. cerevisiae protein Prepro-alpha-factor (PpαF), which was the first protein described to present a post-translational translocation mechanism in eukaryotes, was used as a model. The Ala13Glu point mutation, in the h region of the PpαF signal peptide, has been shown to decrease the translocation rate by up to 50 times. One hypothesis that would explain this phenomenon is that the Ala13Glu mutation decreases the free energy of the transition state of the dissociation process, while increasing the dissociation kinetic constant, in the interaction between the signal peptide and the Sec61 channel, compared to the protein wild type. This hypothesis was studied by force spectroscopy using optical tweezers, a tool that allows the interaction between proteins to be measured at the single molecule level (in singulo). As a first target, the PpαF protein and its Ala13Glu mutant were prepared for manipulation with optical tweezers. To this end, PCR-directed site mutagenesis was carried out to incorporate a cysteine residue, necessary to covalently bind to proteins, at position 165 (Tyr165Cys mutation). The Tyr165Cys and Ala13Glu/Tyr165Cys mutants were then expressed and purified, both with a 6xHis-tag at their C-terminus, by affinity chromatography. A second vital component of the experiment are the DNA handles, which serve as a spacer and as a force standard, due to their characteristic deformation at 67 pN. The handles were synthesized by PCR from a plasmid, using a biotinylated and a thiolated primer, to obtain a final product that forms a disulfide bond to PpαF and binds to the microsphere coated with streptavidin thanks to the incorporated biotin. Third, the yeast Sec61 translocon was purified. For this, microsomal fractions were separated and the translocon was purified from them using digitonin as a detergent. The translocon was prepared for the experiment by incubating with microspheres coated with anti-Sec61 antibodies. The force spectroscopy experiment was performed to obtain the rupture force of the interaction between the PpαF-DNA chimeras and the translocon. The rupture force histograms were filtered from the histogram of the negative control without PpαF, corresponding to the nonspecific interactions that are not under study. The data were fitted to the Dudko-Hummer-Szabo model to obtain the parameters of lifetime (τ0), distance to the transition state (Δx‡) and free energy to the transition state (ΔG‡) of the dissociation process. The curve of best fit was to an exponential decay model (Bell equation), which does not allow to obtain data from ΔG‡. The parameters obtained for wild PpαF were τ0 = 10 ± 4 s and Δx‡ = 1×10-2 ± 6×10-2 nm, and for the Ala13Glu mutant, τ0 = 7 ± 3 s and Δx‡ = 4×10-3 ± 2×10-3 nm were obtained. Δx‡ has a significant difference with p <0.05, but not τ0. The dissociation kinetic constants were calculated as the multiplicative inverse of τ0: koff = 1×10-1 ± 4×10-2 s-1 and 1.4×10-1 ± 5×10-2 s-1 respectively, without significant difference. On the other hand, at the same protein concentrations, spheres with PpαF Ala13Glu interact a significantly lower percentage (31%) with the translocon than those with PpαF with wild-signal peptide (49%). These results would indicate that the translocation defect of the Ala13Glu mutation can be multifactorial. A smaller distance to the transition state implies a greater rigidity of the interaction, while a lower adhesiveness of the spheres points to a negative effect on the association with the translocon. This rejects the original hypothesis...
Sec61 is a protein transporter channel, known as the translocon, found in the membrane of the endoplasmic reticulum in eukaryotes. Its function is to allow the passage of proteins from the cytosol to the reticular lumen in a process known as translocation, which is the first step in the protein secretory pathway. In humans, about 38% of the proteins synthesized by the cell translocate to the reticular lumen. This is because they possess an amino acid sequence, at its N-terminus, known as a “signal peptide”, which plays a role of recruiting the protein to the reticulum membrane and, later, of interaction with the translocon. This last function represents the first step in the translocation process, making it particularly interesting to study. The signal peptide has a poorly conserved sequence between proteins, however, three common regions are distinguished in all of them: an N-terminal region of positively charged residues (n region), a hydrophobic region in the form of an α helix (h region) and a C-terminal region of short-chain polar residues (c region). The h region is essential for the translocation process, as mutations in hydrophobic residues in this sequence dramatically decrease translocation and secretion rates. The h region of the signal peptide acts by inserting it into a "lateral gate" of the Sec61 channel, causing a conformational change that opens the pore and leaves the translocon in an active conformation. To study the translocation process, the S. cerevisiae protein Prepro-alpha-factor (PpαF), which was the first protein described to present a post-translational translocation mechanism in eukaryotes, was used as a model. The Ala13Glu point mutation, in the h region of the PpαF signal peptide, has been shown to decrease the translocation rate by up to 50 times. One hypothesis that would explain this phenomenon is that the Ala13Glu mutation decreases the free energy of the transition state of the dissociation process, while increasing the dissociation kinetic constant, in the interaction between the signal peptide and the Sec61 channel, compared to the protein wild type. This hypothesis was studied by force spectroscopy using optical tweezers, a tool that allows the interaction between proteins to be measured at the single molecule level (in singulo). As a first target, the PpαF protein and its Ala13Glu mutant were prepared for manipulation with optical tweezers. To this end, PCR-directed site mutagenesis was carried out to incorporate a cysteine residue, necessary to covalently bind to proteins, at position 165 (Tyr165Cys mutation). The Tyr165Cys and Ala13Glu/Tyr165Cys mutants were then expressed and purified, both with a 6xHis-tag at their C-terminus, by affinity chromatography. A second vital component of the experiment are the DNA handles, which serve as a spacer and as a force standard, due to their characteristic deformation at 67 pN. The handles were synthesized by PCR from a plasmid, using a biotinylated and a thiolated primer, to obtain a final product that forms a disulfide bond to PpαF and binds to the microsphere coated with streptavidin thanks to the incorporated biotin. Third, the yeast Sec61 translocon was purified. For this, microsomal fractions were separated and the translocon was purified from them using digitonin as a detergent. The translocon was prepared for the experiment by incubating with microspheres coated with anti-Sec61 antibodies. The force spectroscopy experiment was performed to obtain the rupture force of the interaction between the PpαF-DNA chimeras and the translocon. The rupture force histograms were filtered from the histogram of the negative control without PpαF, corresponding to the nonspecific interactions that are not under study. The data were fitted to the Dudko-Hummer-Szabo model to obtain the parameters of lifetime (τ0), distance to the transition state (Δx‡) and free energy to the transition state (ΔG‡) of the dissociation process. The curve of best fit was to an exponential decay model (Bell equation), which does not allow to obtain data from ΔG‡. The parameters obtained for wild PpαF were τ0 = 10 ± 4 s and Δx‡ = 1×10-2 ± 6×10-2 nm, and for the Ala13Glu mutant, τ0 = 7 ± 3 s and Δx‡ = 4×10-3 ± 2×10-3 nm were obtained. Δx‡ has a significant difference with p <0.05, but not τ0. The dissociation kinetic constants were calculated as the multiplicative inverse of τ0: koff = 1×10-1 ± 4×10-2 s-1 and 1.4×10-1 ± 5×10-2 s-1 respectively, without significant difference. On the other hand, at the same protein concentrations, spheres with PpαF Ala13Glu interact a significantly lower percentage (31%) with the translocon than those with PpαF with wild-signal peptide (49%). These results would indicate that the translocation defect of the Ala13Glu mutation can be multifactorial. A smaller distance to the transition state implies a greater rigidity of the interaction, while a lower adhesiveness of the spheres points to a negative effect on the association with the translocon. This rejects the original hypothesis...
Atención progresiva del paciente adulto agudo y crónico descompensado, desde el servicio de emergencia a la atención en las unidades críticas
(Universidad de Chile, 2015-02)
un ítem de
“arriendo” (gasto estimado en 8% de interés anual sobre inversión en el caso de lo
inmobiliario).
Considerando que la demanda de estos servicios en el HCUCH proviene
predominantemente de pacientes de nivel socio-económico C2, C3...
Organización para la Cooperación y el Desarrollo Económico (OCDE). Gráfico 1: Comparativo de Gasto en Salud, participación del gasto público sobre el total del país Fuente: OCDE 8 Gráfico 2: Gasto en per cápita y en porcentaje del PIB Fuente...
Organización para la Cooperación y el Desarrollo Económico (OCDE). Gráfico 1: Comparativo de Gasto en Salud, participación del gasto público sobre el total del país Fuente: OCDE 8 Gráfico 2: Gasto en per cápita y en porcentaje del PIB Fuente...
Costo de reforzamiento en redes de baja tensión debido a la inserción de energía solar residencial y vehículos eléctricos
(Universidad de Chile, 2019)
sobre
todo, por brindarme ayuda y consejos cada vez que la ortografía me causaba problemas.
Mención especial por tu apoyo y compañía sobre todo en este último tiempo, que ha tenido
procesos complejos en varios aspectos.
No puedo dejar de agradecer a...
conocimientos, su apoyo insufrible y por sobre todo su paciencia infinita. También, hacer mención especial a Juanpi, quien durante este último tiempo se convirtió en un amigo muy cercano, luego de compartir la experiencia de intercambio y de trabajar a la par...
conocimientos, su apoyo insufrible y por sobre todo su paciencia infinita. También, hacer mención especial a Juanpi, quien durante este último tiempo se convirtió en un amigo muy cercano, luego de compartir la experiencia de intercambio y de trabajar a la par...