Producción de líquidos iónicos mediante metátesis y cristalización por fundido

Establece las condiciones de dinámica de fluido y termodinámicas adecuadas en un sistema de par salino recíproco multicomponente, el cual, vía reacción de metátesis, logre una eficiente conversión a líquidos iónicos (LIs) de alto valor. Se estudia las características de cristalización del sistema y se aplican procedimientos adicionales de separación ‘downstream’ —destilación y centrifugación— para lograr una alta concentración de los productos. Con esto se buscar llevar a cabo una comparación de procesos alternativos y proponer un procedimiento de producción y concentración basado en cristalización fraccionada para obtener LIs por metátesis vía diálisis en membrana y/o columna de intercambio iónico. La reacción por síntesis directa es la principal vía de producción de LIs. Para la producción de LIs adicionales específicos, sin embargo, no todas las combinaciones anión–catión pueden ser obtenidas a un rendimiento o costo aceptables por esta vía. El intercambio iónico por metátesis representa una vía complementaria, donde el diseño conceptual implicó el uso de eductos de bajo costo junto con un LI precursor. El proceso, acoplado a una etapa de separación vía destilación y cristalización por fundido, representa una alternativa para obtener LIs concentrados. La metátesis fue llevada a cabo por : (1) generación de un sistema de par salino recíproco mediante mezcla de dos eductos, conduciendo a la formación de un sistema ternario o cuaternario a partir del cual el producto puro fue obtenido por cristalización; (2) diálisis Donnan de los eductos mediante sistema de membrana, con el gradiente como única fuerza motriz necesaria para la reacción; (3) electrodiálisis, con la fuerza motriz de intercambio iónico basada en el potencial eléctrico; y (4) intercambio iónico en columna. Se comprobó así la factibilidad técnica de obtener LIs como sal o hidróxido, por sustitución aniónica, incluyéndose un breve análisis económico comparativo.Ionic liquids (ILs) are a very important class of innovative compounds consisting entirely of ions and which are normally liquid at or near room temperature. They are currently becoming an important segment in the chemical research an industry due to their interesting properties, such as, among others, their ability to be applied as practically non-volatile solvents. A wide variety of anion-cation combinations of ILs can be theoretically produced, with a specific application in each case, as solvents in (bio)-catalysis or as electrolytes among other current and potential uses. A reaction process of direct synthesis is essentially the way through which the first series of ILs have been and are still produced nowadays. This basically involves first the quaternization of molecules that can easily complex to various metal ions (as organometallic agents), like amine, phosphine or heterocyclic nitrogen rings, with the corresponding cation as the intermediary product, which ultimately reacts with an alkylation agent forming the IL. A number of important ILs has thus been generated from established firms in the chemical industry. For the production of further specifically tailored and highly valuable ILs, however, direct synthesis alone may not always be enough, since not all the anion - cation combinations needed for each particular application can actually be obtained at a high yield and/or at a low cost through this method. There exists, though, a complementary path for generating ILs, and it is based on the ion exchange principle; highly valuable ILs can potentially be produced by this reaction path known as metathesis, a classic type of reaction that basically implies the exchange of ions from two educts being put into contact. This concept, as applied in the presented work, implies the use of a readily available, low-cost educts, with a low-value ‘precursor’ IL itself being one of these educts. This process, when coupled with a final separation or concentration enrichment of the resulting IL by means of distillation and fractional (melt) crystallization, represents an interesting and potentially feasible alternative for obtaining concentrated or high-purity tailored compounds of this kind. Metathesis here can be accomplished by several approaches; each one of them was studied in detail in this work. A first approach in the metathesis reaction was the generation of a reciprocal salt pair system through the mixture of two educts; this led to the formation of a ternary or quaternary system, from where the desired product can be obtained in high purity degree by final crystallization. A second approach in this work was the Donnan dialysis of the educts through a membrane system. The advantage of this method lies in the gradient being the only real driving force for the reaction as well as the feasibility of performing it at mild temperature conditions. A third approach was by means of electrodialysis. Here, the driving force for ion exchange is based on the electrical potential. Finally, a fourth approach was the ion exchange through a column. Through these different approaches, all of them based on the principle of metathesis, it was technically possible to obtain tailored ILs in the form of salts or as hydroxides, by anion substitution. Moreover, provided there is a feasible production of ILs by means of anion substitution, the potential application of the ion exchange principle to tailor even more IL salts by means of cation substitution will then also be a strong issue.Tesi

Kerf Taper Defect Minimization Based on Abrasive Waterjet Machining of Low Thickness Thermoplastic Carbon Fiber Composites C/TPU

Carbon fiber-reinforced thermoplastics (CFRTPs) are materials of great interest in industry. Like thermosets composite materials, they have an excellent weight/mechanical properties ratio and a high degree of automation in their manufacture and recyclability. However, these materials present di culties in their machining due to their nature. Their anisotropy, together with their low glass transition temperature, can produce important defects in their machining. A process able to machine these materials correctly by producing very small thermal defects is abrasive waterjet machining. However, the dispersion of the waterjet produces a reduction in kinetic energy, which decreases its cutting capacity. This results in an inherent defect called a kerf taper. Also, machining these materials with reduced thicknesses can increase this defect due to the formation of a damage zone at the beginning of cut due to the abrasive particles. This paper studies the influence of cutting parameters on the kerf taper generated during waterjet machining of a thin-walled thermoplastic composite material (carbon/polyurethane, C/TPU). This influence was studied by means of an ANOVA statistical analysis, and a mathematical model was obtained by means of a response surface methodology (RSM). Kerf taper defect was evaluated using a new image processing methodology, where the initial and final damage zone was separated from the kerf taper defect. Finally, a combination of a hydraulic pressure of 3400 bar with a feed rate of 100 mm/min and an abrasive mass flow of 170 g/min produces the minimum kerf taper angle

Dangerous discourses and uncomfortable silences

In this paper, two teacher educators, a Latino man and an Asian American woman, reflect on their experiences in their graduate teacher-education classes after a controversial book talk and lecture about racism in higher education took place at one of the most diverse institutions of higher learning in the United States. Using critical race and dialogic frameworks, they analyze issues of race, power, and White privilege in academia and probe the reasons why, despite efforts to incorporate multicultural training in teacher education programs, discussing race can be an uncomfortable, threatening, and even cathartic experience to participants

Síndrome mesencefálica alternativa: síndrome de Weber em 2 pacientes HIV positivos do sexo masculino com toxoplasmose cerebral

This report describes the case of two male HIV-positive patients who were not receiving treatment and whose diagnosis was confirmed by serology testing. Both patients developed midbrain stroke syndrome and the structural injury, whichwas caused by a central nervous system infection due to cerebral toxoplasmosis, was verified by brain magnetic resonance imaging. This condition was confirmed by cerebrospinal fluid serology testing.Weber’s syndrome is a very rare type of midbrain stroke syndrome with little information available on its symptoms and evolution. It was first described by Sir Herman David Weber in 1863 and is characterized by ipsilateral injury of the third cranial nerve fascicle with contralateral hemiparesis due to injury of the corticospinal and corticobulbar tracts of the cerebral peduncle. Its causes range from ischemic or hemorrhagic processes, which damage the third cranial nerve fascicle and cerebral peduncle, to brain tumors, aneurysms, extradural hematomas and infectious diseases that behave like spreading processes.The assessed patients showed clinical signs and symptoms such as ptosis; vertical double vision; difficulty standing up; hemiparesis; hyporeflexia; decreased superficial and deep sensation; poor balance and coordination; third cranial nervepalsy; slurred speech; intermittent disorientation in time, place and person; and facial asymmetry. Oral trimethoprim-En este reporte se describen dos casos de pacientes varones con VIH diagnosticados por serología, que no estaban recibiendo tratamiento. Ambos pacientes desarrollaron el síndrome alterno mesencefálico y la lesión estructural, causada por la infección del sistema nervioso central por toxoplasmosis cerebral, confirmada mediante una resonancia magnética cerebral. Esta condición se constató por serología en líquido cefalorraquídeo.El síndrome de Weber es un tipo de síndrome alterno mesencefálico poco frecuente y existe poca información de su clínica y evolución. Fue descrito por sir Herman David Weber en 1863, y se caracteriza por la lesión ipsilateral del fascículo del III par craneal, con presencia de hemiparesia contralateral debida a la lesión de la vía corticoespinal ycorticobulbar del pedúnculo cerebral. Las causas que lo originan incluyen tanto procesos isquémicos o hemorrágicos, que lesionan el fascículo del III par craneal y pedúnculo cerebral, como neoplasias intraencefálicas, aneurismas, hematomas extradurales y procesos infecciosos que se comportan como procesos expansivos.Los pacientes evaluados presentaron clínica de ptosis palpebral, visión doble vertical, dificultad para bipedestación, hemiparesia, hiporreflexia, sensibilidad superficial y profunda disminuidas, equilibrio y coordinación alterados, III par parético, habla incoherente, desorientación en tiempo, espacio y persona de manera intermitente y asimetría facial. Para la toxoplasmosis se aplicó un tratamiento específico con trimetropim-sulfametoxasol, clindamicina y prednisona por vía oral, lo cual permitió una mejoría del cuadro clínico.En el presente caso clínico se presenta la secuencia de los hechos, manejo y breve revisión de la literatura para su consideración como diagnóstico y su relevancia en el paciente con VIH-toxoplasmosis del sistema nervioso central.Relatamos dois casos de pacientes do sexo masculino com diagnóstico prévio de HIV, que desenvolveram síndrome do mesencéfalo alternado, confirmada por ressonância magnética cerebral, devido a toxoplasmose cerebral; confirmado por sorologia. Este quadro clínico é pouco frequente e com pouca descrição de seus sintomas e evolução. Os pacientes aqui apresentados desenvolveram ptose, visão dupla vertical, dificuldade em ficar em pé, hemiparesia, hiporreflexia, diminuição da sensibilidade superficial e profunda, equilíbrio e coordenação alterados, III par parético, fala incoerente, desorientação no tempo, espaço e pessoa de forma intermitente; e assimetria facial. O tratamento específico para toxoplasmose foi feito com trimetoprim-sulfametoxasol oral, clindamicina e prednisona; com isso, conseguiu-se a melhora do quadro clínico. Apresentamos aqui a sequência de eventos, manejo e uma breve revisão da literatura para sua consideração como diagnóstico em pacientes com HIV-toxoplasmose do SNC

On the Potential Mismatch between the Function of the Bayes Factor and Researchers’ Expectations

The aim of this study is to investigate whether there is a potential mismatch between the usability of a statistical tool and psychology researchers’ expectation of it. Bayesian statistics is often promoted as an ideal substitute for frequentists statistics since it coincides better with researchers’ expectations and needs. A particular incidence of this is the proposal of replacing Null Hypothesis Significance Testing (NHST) by Null Hypothesis Bayesian Testing (NHBT) using the Bayes factor. In this paper, it is studied to what extent the usability and expectations of NHBT match well. First, a study of the reporting practices in 73 psychological publications was carried out. It was found that eight Questionable Reporting and Interpreting Practices (QRIPs) occur more than once among the practitioners when doing NHBT. Specifically, our analysis provides insight into possible mismatches and their occurrence frequencies. A follow-up survey study has been conducted to assess such mismatches. The sample (N = 108) consisted of psychology researchers, experts in methodology (and/or statistics), and applied researchers in fields other than psychology. The data show that discrepancies exist among the participants. Interpreting the Bayes Factor as posterior odds and not acknowledging the notion of relative evidence in the Bayes Factor are arguably the most concerning ones. The results of the paper suggest that a shift of statistical paradigm cannot solve the problem of misinterpretation altogether if the users are not well acquainted with the tools

Valorización de Enel Generación Perú S.A.A. (antes Edegel S.A.A.)

El presente documento tiene como objetivo estimar el valor fundamental de la acción de Enel Generación Perú S.A.A., empresa dedicada a la generación de energía en el Perú, que permita orientar al inversionista en la toma de decisiones relacionadas a la compra, venta o retención de la acción. Entre los principales supuestos empleados en la valorización, se encuentra el incremento de los ingresos sustentado en el crecimiento de la demanda de energía proyectada por el Comité de Operación Económica del Sistema Interconectado Nacional - COES. Esta mayor generación de ingresos, junto a la emisión de nueva deuda, permitiría cubrir las necesidades de inversión, considerando el desarrollo de nuevos proyectos energéticos destinados a incrementar su oferta. La valorización se efectúa a septiembre de 2016, habiéndose considerado un periodo de proyección de 10 años, una perpetuidad con una tasa de crecimiento de 2,2% y una tasa de descuento (WACC) de 9,09%. Los resultados de la valorización muestran un valor fundamental del patrimonio de S/ 8.878 millones, mayor al valor de mercado a septiembre de 2016 (S/ 8.101 millones). En valores relativos a la acción, según nuestros resultados, el valor fundamental es de S/ 3,07, mayor que la cotización de la acción publicada en la Bolsa de Valores de Lima -BVL para dicha fecha (S/ 2,80) por lo que se recomendaría “comprar” la acción. Por otro lado, se resalta que el valor fundamental se encontraría incluido en el rango estimado mediante el método alternativo de múltiplos (S/ 3,06 - S/ 3,43) y alineado a los valores de mercado estimados por las Sociedades Agentes de Bolsa - SAB (S/ 2,95; S/ 3,57 y S/ 3,75) lo que otorga mayor robustez a nuestra recomendación de compra

Modelos de transição do ensino à profissão

Dissertação para obtenção do grau de Mestre em Arquitectura, apresentada na Universidade de Lisboa - Faculdade de Arquitectura

Preface - Creativity and HCI: From Experience to Design in Education

Abstract included in text

The Life and Death of Dense Molecular Clumps in the Large Magellanic Cloud

We report the results of a high spatial (parsec) resolution HCO+ (J = 1-0) and HCN (J = 1-0) emission survey toward the giant molecular clouds of the star formation regions N105, N113, N159, and N44 in the Large Magellanic Cloud. The HCO+ and HCN observations at 89.2 and 88.6 GHz, respectively, were conducted in the compact configuration of the Australia Telescope Compact Array. The emission is imaged into individual clumps with masses between 10^2 and 10^4 solar masses and radii of <1 pc to ~2 pc. Many of the clumps are coincident with indicators of current massive star formation, indicating that many of the clumps are associated with deeply-embedded forming stars and star clusters. We find that massive YSO-bearing clumps tend to be larger (>1 pc), more massive (M > 10^3 solar masses), and have higher surface densities (~1 g cm^-2), while clumps without signs of star formation are smaller (<1 pc), less massive (M < 10^3 solar masses), and have lower surface densities (~0.1 g cm^-2). The dearth of massive (M >10^3 solar masses) clumps not bearing massive YSOs suggests the onset of star formation occurs rapidly once the clump has attained physical properties favorable to massive star formation. Using a large sample of LMC massive YSO mid-IR spectra, we estimate that ~2/3 of the massive YSOs for which there are Spitzer mid-IR spectra are no longer located in molecular clumps; we estimate that these young stars/clusters have destroyed their natal clumps on a time scale of at least 3 x 10^{5}$ yrs.Comment: Accepted to ApJ 3-19-201