Facultad de Ciencias Básicas
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Ítem A bimodal discrete shifted poisson distribution. A case study of tourists' length of stay(2020) Gómez-Déniz, E.; Pérez-Rodríguez, J.V.; Reyes, J.; Gómez, H.W.Ítem A Gamma-type distribution with applications(2020) Iriarte, Y.A.; Varela, H.; Gómez, H.J.; Gómez, H.W.Ítem A parametric quantile regression model for asymmetric response variables on the real line(2020) Gallardo, D.I.; Bourguignon, M.; Galarza, C.E.; Gómez, H.W.Ítem A power maxwell distribution with heavy tails and applications(2020) Segovia, F.A.; Gómez, Y.M.; Venegas, O.; Gómez, H.W.Ítem A reliability model based on the incomplete generalized integro-exponential function(2020) Astorga, J.M.; Reyes, J.; Santoro, K.I.; Venegas, O.; Gómez, H.W.Ítem A transmuted version of the generalized half-normal distribution(2019) Salinas, H.S.; Iriarte, Y.A.; Astorga, J.M.Ítem An asymmetric bimodal distribution with application to quantile regression(2019) Gómez, Y.M.; Gómez-Déniz, E.; Venegas, O.; Gallardo, D.I.; Gómez, H.W.Ítem An asymmetric distribution with heavy tails and its expectation-maximization (EM) algorithm implementation(2019) Olmos, N.M.; Venegas, O.; Gómez, Y.M.; Iriarte, Y.A.Ítem Aqueous Dried Extract of Skytanthus acutus Meyen as Corrosion Inhibitor of Carbon Steel in Neutral Chloride Solutions(2021) Luis Cáceres; Yohana Frez; Felipe Galleguillos; Alvaro Soliz; Benito Gómez-Silva; Jorge BorquezThe implementation of corrosion engineering control methods and techniques is crucial to extend the life of urban and industrial infrastructure assets and industrial equipment affected by natural corrosion. Then, the search of stable and environmentally friendly corrosion inhibitors is an important pending task. Here, we provide experimental evidence on the corrosion inhibitory activity of aqueous extracts of Skytanthus acutus Meyen leaf, a native plant from the Atacama Desert in northern Chile. Skytanthus extracts as a powder should be prepared at 55 °C to avoid thermal decomposition and loss of corrosion inhibitory activity. Corrosion of carbon steel AISI1020 immersed in 0.5 M NaCl was evaluated in the presence of different doses of Skytanthus extract by complementary and simultaneous linear polarization, electrochemical impedance spectroscopy, and weight-loss technique under high hydrodynamic conditions. Mixed Potential Theory was applied to confirm the electrochemical activity of the extract inhibitory capabilities. The Skytanthus extracts reached a 90% corrosion inhibitory efficiency when tested at 100 to 1200 ppm in a time span of 48 h, through an electrochemical interaction between the extract inhibitor component and the carbon steel surface. The corrosion inhibition activity observed in Skytanthus dry extracts involves a protective film formation by a mechanism that includes an iron dissolution at the expense of either oxygen reduction and/or hydrogen evolution, followed by a ferrous-ferric iron cycling, the formation of an iron complex and adsorption to the metal surface, and, finally, desorption or degradation of the protecting film. The water-soluble plant extract was subjected to HPLC-MS analyses that rendered 14 major signals, with quinic acid, protocatechuic acid, chlorogenic acid isomers, vanillic acid hexoside, and patuletin 3-methoxy-7-glucoside as the most abundant components. Then, we propose that a phenolic derivative is responsible for the corrosion inhibitory activity found in Skytanthus extracts.Ítem Betel and tobacco chewing habit and its relation to risk factors for periodontal disease(2018) Giovannoni, M.L.; Valdivia-Gandur, I.; Lozano de Luaces, V.; Varela Véliz, H.; Balasubbaiah, Y.; Chimenos-Küstner, E.Ítem Bimodal extension based on the skew-t-normal distribution(2019) Amiri, M.; Gómez, H.W.; Jamalizadeh, A.; Towhidi, M.Ítem Bivariate power-skew-elliptical distribution(2020) Martínez-Flórez, G.; Tovar-Falón, R.; Gómez, H.W.Ítem Censored bimodal symmetric-asymmetric families(2018) Martínez-Flórez, G.; Bolfarine, H.; Gómez, H.W.Ítem Chemical Profiling, Antioxidant, Anticholinesterase, and Antiprotozoal Potentials of Artemisia copa Phil. (Asteraceae)(2020) Maria José Larrazábal-Fuentes; Carlos Fernández-Galleguillos; Jenifer Palma-Ramírez; Javier Romero-Parra; Kevin Sepúlveda; Jorge González; Adrián Paredes; Jorge Bórquez; Mario J. Simirgiotis; Javier Echeverría; Alexandra GaletovićArtemisia copa Phil. (Asteraceae) (known as copa-copa) is a native species of Chile used as an infusion in traditional medicine by Atacameños people in the Altiplano, highlands of northern Chile. In this research, we have investigated for the first time the cholinesterase inhibition potential against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), and the chemical profiling of the infusions prepared from the aerial parts of A. copa by high resolution spectrometry. In addition, total phenolic, total flavonoid content, antioxidant (DPPH, FRAP, and ORAC) and antiprozoal activity were tested. Artemisia copa showed good inhibitory activity against AChE and BChE (3.92 ± 0.08 µg/ml and 44.13 ± 0.10 µg/ml). The infusion displayed a total phenolics content of 155.6 ± 2.9 mg of gallic acid equivalents/g and total flavonoid content of 5.5 ± 0.2 mg quercetin equivalents/g. Additionally, trypanocidal activity against Trypanosoma cruzi was found (LD50 of 131.8 µg/ml). Forty-seven metabolites were detected in the infusion of A. copa including several phenolic acids and flavonoids which were rapidly identified using ultrahigh performance liquid chromatography orbitrap mass spectrometry analysis (UHPLC-Orbitrap-MS) for chemical profiling. The major compounds identified in the infusions were studied by molecular docking against AChE and BChE. The UHPLC-MS fingerprints generated can be also used for the authentication of these endemic species. These findings reveal that A. copa infusions can be used as beverages with protective effects.Ítem Corrigendum to: Skew-normal alpha-power model (Statistics, (2014), 48, 6, (1414-1428), 10.1080/02331888.2013.826659)(2018) Salinas, H.S.; Gómez, H.W.; Martínez-Flórez, G.; Bolfarine, H.Ítem Extended exponential regression model: Diagnostics and application to mineral data(2020) Gómez, Y.M.; Gallardo, D.I.; Leão, J.; Gómez, H.W.Ítem Flexible Birnbaum-Saunders distribution(2019) Martínez-Flórez, G.; Barranco-Chamorro, I.; Bolfarine, H.; Gómez, H.W.Ítem Generalized modified slash Birnbaum-Saunders distribution(2018) Reyes, J.; Barranco-Chamorro, I.; Gallardo, D.I.; Gómez, H.W.Ítem Health status and self -efficacy in elderly users in primary care(2017) Tapia P., C.; Iturra M., V.; Valdivia R., Y.; Varela V., H.; Jorquera C., M.; Carmona G., A.Ítem Melatonin relations with respiratory Quotient Weaken on acute exposure to high altitude(2018) Tapia, M.; Wulff-Zottele, C.; De Gregorio, N.; Lang, M.; Varela, H.; Serón-Ferré, M.J.; Vivaldi, E.A.; Araneda, O.F.; Silva-Urra, J.; Gunga, H.-C.; Behn, C.