Deterioro del concreto en ambientes urbanos de Colombia

RESUMEN: La combinación de contaminantes atmosféricos tales como el dióxido de carbono y los iones cloruro tiene un efecto sinérgico que acelera los procesos de degradación del concreto. Sin embargo, en Colombia no se han llevado a cabo estudios de campo en ambiente urbanos reales que permitan evaluar el deterioro del concreto y su relación con la carbonatación y el contenido de iones cloruro. En este trabajo, probetas cilíndricas de concreto fueron expuestas en diferentes atmósferas urbanas con el ánimo de establecer correlaciones entre el deterioro y el tipo de atmósferas. Para evaluar la velocidad de corrosión de la barra de refuerzo y el porcentaje de carbonatación de la probeta se empleó la Espectroscopía de Impedancia Electroquímica (EIS) y ensayos fisicoquímicos con fenolftaleína, respectivamente.ABSTRACT: The combination of atmospheric pollutants, such as carbon dioxide and chlorides has a synergistic effect accelerating the degradation process of concrete. However, in Colombia it has not been carried out field tests in real urban environments to assess the deterioration of concrete and its relation to both, carbonation and chloride content. In this work, cylindrical concrete probes were exposed in different urban atmospheres with the aim of establishing correlations between the concrete deterioration and the type of atmosphere. To evaluate the corrosion rate on the rebar and the percentage of carbonated probe, Electrochemical Impedance Spectroscopy (EIS) and physicochemical tests with phenolphthalein were used, respectively

Performance evaluation of ceramic insulators coated with titanium dioxide films to reduce soiling

RESUMEN: El ensuciamiento de aisladores eléctricos en servicio expuestos a la atmósfera constituyen un gran inconveniente para el sector eléctrico, debido a que en la superficie se deposita material de naturaleza orgánica e inorgánica, formando una capa que en presencia de humedad puede volverse conductora, produciendo diferentes fenómenos que podrían deteriorar las propiedades aislantes del elemento y finalmente conducir a la ruptura del mismo, afectando principalmente el suministro de la energía eléctrica. Actualmente se encuentra en fase de desarrollo un método que consiste en la aplicación de una película de dióxido de titanio para minimizar la acumulación de suciedad en los aisladores de porcelana sin afectar las propiedades eléctricas de los mismos. Se evaluó el desempeño de dos espesores diferentes (una y dos capas) de dicha película en aisladores de porcelana, para lo cual se realizaron pruebas de adherencia, ángulo de contacto, corriente de fuga, tensión de flameo en seco y ensayos de erosión en laboratorio. Finalmente, se evaluó el desempeño en aisladores en servicio en una torre de transmisión de energía. Los aisladores recubiertos exhiben un buen desempeño en las pruebas de laboratorio. Además, tras 5 meses de exposición en servicio en la línea de alta tensión energizada, se observa una disminución en el ensuciamiento.ABSTRACT: The soiling of in-service electrical insulators exposed to the atmosphere is a major problem in power transmission lines. Several inorganic and organic particulate materials are deposited on insulator surfaces forming a layer that could become conductive in the presence of moisture. This produces different phenomena that could deteriorate the insulating properties of the material and eventually lead to its rupture, affecting the electrical energy supply. Currently, a method based in the application of a titanium dioxide film is being developed. This method tries to minimize the pollution accumulation on the porcelain insulators without affecting their electrical properties. In this work the performance of two different thicknesses of the coating film on the porcelain insulators was evaluated by means of contact angle, adhesion, leakage current, dry-flashover voltage and erosion laboratory tests. Finally, the in-service behavior of coated and no-coated insulators installed in a power transmission tower was evaluated. The coated insulators showed a good performance in the laboratory tests. Moreover, before 5 months of exposure in the energized power line, a decrease in the soiling was observed

Synthesis, Crystal Structure, Spectroscopic Characterization, DFT Calculations and Cytotoxicity Assays of a New Cu(II) Complex with an Acylhydrazone Ligand Derived from Thiophene

Anew Cu(II) complex is synthetized by the reaction of copper nitrate and aN-acylhydrazone ligand obtained from the condensation of o-vanillin and 2-thiophecarbohydrazide (H2L). The solidstate structure of [Cu(HL)(H2O)](NO3) H2O, or CuHL for simplicity, was determined by X-ray diffraction. In the cationic complex, the copper center is in a nearly squared planar environment with the nitrate interacting as a counterion. CuHL was characterized by spectroscopic techniques, including solid-state FTIR, Raman, electron paramagnetic resonance (EPR) and diffuse reflectance and solution UV-Vis electronic spectroscopy. Calculations based on the density functional theory (DFT) assisted the interpretation and assignment of the spectroscopic data. The complex does not show relevant antioxidant activity evaluated by the radical cation of 2,20-azinobis(3-ethylbenzothiazoline- 6-sulfonic acid) diammonium salt (ABTS) method, being even less active than the free ligand as a radical quencher. Cytotoxicity assays of CuHL against three human tumor cell lines, namely MG-63, A549 and HT-29, revealed an important enhancement of the effectiveness as compared with both the ligand and the free metal ion. Moreover, its cytotoxic effect was remarkably stronger than that of the reference metallodrug cisplatin in all cancer cell lines tested, a promissory result in the search for new metallodrugs of essential transition metals.Centro de Química InorgánicaInstituto de Física La Plat

Cu(II) and Zn(II) complexes with a poly-functional ligand derived from o-vanillin and thiophene : Crystal structure, physicochemical properties, theoretical studies and cytotoxicity assays against human breast cancer cells

The interaction of a poly-functional ligand derived of o-vanillin and 2-thiophenemethylamine (oVATPNH2) with transition metal ions, Cu(II) and Zn(II) leads to the formation of stable coordination compounds, namely [Cu(oVATPNH2)2] and [Zn(oVATPNH2)2]. Their crystal structures have been determined by X-ray diffraction methods. Two molecules of the deprotonated ligand acting as bidentate build a nearly square planar environment around Cu(II) and a distorted tetrahedral coordination arrangement for Zn(II). The complexes were characterized by spectroscopic techniques, including solid state FTIR, Raman, EPR and diffuse reflectance and solution UV-vis and EPR. Their thermal behavior has been analyzed by means of TGA and DTA. DFT theoretical studies, using computational methods based on DFT, were employed to assist the interpretation and assignment of spectroscopic data. Cytotoxicity assays against two human breast cancer cell lines, namely MCF-7 and MDA-MB-231, revealed an enhancement of effectiveness of the complexes as compared with both the ligand and the free metal ions. The results for the copper compound are promising, as its cytotoxic effect was stronger than the reference metallodrug cisplatin in both cancer cell lines tested.Centro de Química InorgánicaInstituto de Física La Plat

Role of age and comorbidities in mortality of patients with infective endocarditis

Purpose: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. Methods: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015. Patients were stratified into three age groups:<65 years, 65 to 80 years, and = 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. Results: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 = 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients =80 years who underwent surgery were significantly lower compared with other age groups (14.3%, 65 years; 20.5%, 65-79 years; 31.3%, =80 years). In-hospital mortality was lower in the <65-year group (20.3%, <65 years;30.1%, 65-79 years;34.7%, =80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%, =80 years; p = 0.003).Independent predictors of mortality were age = 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI = 3 (HR:1.62; 95% CI:1.39–1.88), and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared, the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. Conclusion: There were no differences in the clinical presentation of IE between the groups. Age = 80 years, high comorbidity (measured by CCI), and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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En busca del rostro de O´Higgins : metodología de reconstrucción de imagen de personajes históricos

Memoria para optar al título de Diseñador Gráfico¿Qué? Metodología de reconstrucción de imagen de personajes históricos, que consta de 15 pasos sistemáticos, basados en el estudio y análisis de las representaciones visuales y descripciones escritas, así como también en una serie de elementos que entregan información fenotípica. Como resultado, el Sistema entrega un acercamiento fisonómico del personaje. ¿Por qué? Aún cuando en el último tiempo se observa un gran numero de reconstrucciones faciales que utilizan variados métodos, estas carecen de profundidad en el aspecto metodológico y/o priorizan ciertas áreas del saber en desmedro de otras. En general los sistemas que han repercutido públicamente se centran en su resultado (la imagen que develan) dejando en segundo plano toda la riqueza investigativa y técnica del proceso. No hay ningún documento al que podamos acudir si queremos conocer cada paso del desarrollo y menos si es que queremos aplicarla con algún otro personaje. La mayoría de las metodologías se aproxima desde las ciencias naturales, incorporando conocimientos de la medicina forense. Dejando de lado así otro tipo de elementos, como por ejemplo el estudio de representaciones, que pueden ser abordados de mejor forma desde las disciplinas que se centran en el estudio de las imagen. ¿Para qué? ¿Para quiénes? Generar una alternativa metodológica desde las ciencias visuales y sociales, como una respuesta a la predominancia de las ciencias naturales frente a este tipo de Sistemas. Aportando una solución rigurosa, pero a la vez de fácil implementación interdisciplinar, para todo aquel que quiera reconstruir la imagen de un personaje histórico

Effect of heat treatment on the tribological properties of Nickel-Boron electroless coating

Nickel-Boron autocatalytic coatings are widely used in several industries to improve mechanical properties of materials such as hardness and wear resistance. Tribological properties were evaluated in Ni-B autocatalytic coatings deposited on AISI/SAE 1018 carbon steel before and after a heat treatment at 450 °C for one hour. Tribological tests were carried out by dry sliding, using a load of 5 N and a sliding speed of 0.012 m/s, in a homemade ball-on-disk tribometer, which followed ASTM G99 standard. According to the tribological evaluation, the heat treatments applied to Ni-B coatings improved their tribological performance. This research corroborates that by applying an adequate heat treatment, hardness and wear resistance of Ni-B coatings can be improved significantly.Los recubrimientos autocatalíticos de níquel-boro son utilizados en diferentes industrias para mejorar las propiedades mecánicas de materiales, como la dureza y la resistencia al desgaste. En esta investigación se evaluaron las propiedades tribológicas de recubrimientos autocatalíticos Ni-B depositados sobre acero al carbono AISI/SAE 1018 antes y después de aplicar un tratamiento térmico a 450 °C durante 1 hora. Adicionalmente, se realizaron ensayos tribológicos por deslizamiento en seco, utilizando una carga de 5 N y una velocidad de deslizamiento de 0.012 m/s, en un tribómetro ball-on-disk fabricado por el CIDEMAT de acuerdo con la norma ASTM G99. De acuerdo con la evaluación tribológica, se estableció que el tratamiento térmico aplicado mejora significativamente el rendimiento tribológico de los recubrimientos autocatalíticos Ni-B