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PublicaciónEsterification and Characterization of Starch From Andean Tubers(Wiley, 2019)Starch is isolated from the Andean tubers olluco (Ollucus tuberosus) and oca (Oxalis tuberosa) and modified with octenylsuccinic anhydride (OSA); subsequently, the morphological, molecular, and physicochemical characteristics are evaluated. The isolated starch of olluco and oca results in a powder with a purity of 93.2 and 92.8%, respectively; the amylose content of starch isolated from olluco and oca are 27.1 and 28.2%, respectively.
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PublicaciónMonumental Inca remains and past seismic disasters: A relational database to support archaeoseismological investigations and cultural heritage preservation in the Andes(Elsevier B.V., 2021)As recent dramatic and numerous examples demonstrate, earthquakes still constitute a significant threat to cultural heritage (Bam 2003; L'Aquila 2009; Haiti 2010; Nepal 2015). By damaging the historical legacy, telluric phenomena affect economic and touristic incomes and alter regional identities and collective psyche. In the Andes, as in other emerging regions across the globe, deficient seismic hazard assessments, constant lack of resources, and inadequate maintenance programs are additional challenges for cultural heritage management. As part of our archaeoseismological investigation in the Cusco area (Peru), we developed a relational database, which seeks to identify, record and inventory seismic damage in pre-Columbian architecture. This work presents the main characteristics of the structure and design of the RISC (Risque sismique, Incas et Socie ' te ' a` Cusco) database and its contribution in supporting the fieldwork organization and facilitating the data acquisition. The collected architectonical evidence constitutes the first large archaeoseismological dataset in South America and will provide valuable complementary data in Peru to regional seismic hazard studies. We here aim to demon-strate that an ergonomic and user-friendly interface has a role to play in supervising and preserving the cultural heritage in active seismic areas. By converting ad-hoc surveys into routine inspections, RISC could become an effective low-tech monitoring system, providing relevant support for disaster risk reduction plans in archaeo-logical sites conservation. We stress the necessity of adopting cost-effective and easy-to-implement tools for cultural heritage monitoring in emerging countries through this case study. Our database may represent a relevant methodological background and template for further initiatives in both fields of archaeoseismology and cultural heritage protection.
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PublicaciónVacancy ordered gamma-Fe2O3 nanoparticles functionalized with nanohydroxyapatite: XRD, FTIR, TEM, XPS and Mossbauer studies(Elsevier B.V., 2016)Vacancy ordered maghemite (γ-Fe2O3) nanoparticles functionalized with nanohydroxyapatite (HAp – Ca10(PO4) 6(OH)2) have been successfully synthesized using an inexpensive co-precipitation chemical route. Evidence for the presence of vacancy order in maghemite was shown by the superstructure lines observed in X-ray diffraction. The adsorption of carboxyl groups of citric acid (C6H8O7) onto γ-Fe2O3 nanoparticles was investigated by FTIR, XPS and Mössbauer spectroscopy.
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PublicaciónDevelopment of the phase composition and the properties of Ti2AlC and Ti3AlC2 MAX-phase thin films – A multilayer approach towards high phase purity(Elsevier B.V., 2021)MAX phase thin films have been synthesized by thermal treatment of a Ti-Al-C multilayer system. The preparation of the multilayer system was carried out via magnetron sputtering. Based on the thickness ratio among the individual nanoscale monolayers (Ti, Al, C), the resulting MAX phase stoichiometry can be controlled. This paper describes the synthesis of both Ti2AlC and Ti3AlC2 MAX phases from the same precursor multilayer system which is composed of a sequence of Ti/Al/C pure elemental single layers with thicknesses of 14, 6, and 3.5 nm, respectively. This sequence is repeated 22 times with a total thickness of around 500 nm. Rapid thermal treatment tests were performed to study the phase development. The Ti2AlC MAX phase forms in a temperature range below 850 °C, whereas the Ti3AlC2 MAX phase starts to form at temperatures above 850 °C and reaches its highest phase purity at 950 °C. The thin film structures were studied by X-ray diffraction and Raman spectroscopy. Furthermore, the electrical and mechanical properties were investigated to gain more insights regarding the phase transformation and their influence on the thin film properties. © 2020 Elsevier B.V.
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PublicaciónSimple light-emitting electrochemical cell using reduced graphene oxide and a ruthenium (II) complex(Optica Publishing Group, 2017)We report the use of conducting substrates from reduced graphene oxide (rGO) applied in light-emitting electrochemical cells (LECs) in which we used an electroluminescent polymer as a light-emitting layer. The emitting layer was composed of an organic metal complex of tris(2, 2′-bipyridine) ruthenium (II) linked to the sodium tetrafluoroborate anion ([Ru(bpy)3]+2)(BF4)−1. The luminance generated from the electroluminescent device was 6.89 Cd/m2 when applying a voltage of 13.48 V and a current of 10.19 mA. The luminance of this device was kept on almost constant for 36.84 min. The prolonged lifetime of the electrochemical device was achieved by depositing an rGO thin layer with a 161.3 nm thickness inside the LEC structure.
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