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Ac susceptibility studies under dc fields in superspinglass nanomaghemite-multiwall carbon nanotube hybrid
No full textMagnetic properties of maghemite (?-Fe2O3 ) nanoparticles grown on activated multiwall carbon nanotubes have been studied by alternating current (AC) magnetic susceptibility experiments performed under different temperatures, frequencies, and applied magnetic fields. Transmission elec-tron images have suggested that the ?-Fe2O3 nanoparticles are not isolated and have an average size of 9 nm, but with a relatively broad size distribution. The activation energies of these 9 nm ?-Fe2O3 nanoparticles, determined from the generalized Vogel–Fulcher relation, are reduced upon increasing the direct current (DC) field magnitude. The large activation energy values have indi-cated the formation of a superspinglass state in the ?-Fe2O3 nanoparticle ensemble, which were not observed for pure ?-Fe2O3 nanoparticles, concluding that the multiwall carbon nanotubes favored the appearance of highly concentrated magnetic regions and hence the formation of superspinglass state. Magnetic relaxation studies, using Argand diagrams recorded for DC probe fields (<20 kOe) below the magnetic blocking temperature at 100 and 10 K, have revealed the presence of more than one relaxation process. The behavior of the ensemble of ?-Fe2O3 nanoparticles can be related to the superspinglass state and is also supported by Almeida–Thouless plots. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Fabrication and characterization of copper (II) oxide/iron (III) oxide thin film heterostructures for trace arsenic (III) removal in water
No full textThe work described in this paper was financially supported by the National Fund for the Scientific and Technological Development (FONDECYT), Grant No. 237–2015-FONDECYT. The authors thank Dr. Breno Pannia Espósito and the LABQAM of the Chemistry Institute of USP for the analysis of the samples. In addition, authors thank Dr. Pierre Ramos Apestegui for his excellent technical assistance with scanning electron microscopy observation.In this study, nano-heterostructures based on copper (II) oxide/iron (III) oxide (CuO/α-Fe2O3) thin films were fabricated by a dip-coating technique using aqueous solutions. The heterostructures were deposited on fluorine-doped tin oxide glass substrates varying the CuO film thickness. From a detailed characterization using Fourier transform-infrared and X-ray diffraction the formation of CuO (tenorite)/α-Fe2O3 (hematite) was demonstrated. Atomic force microscopy provided valuable information on the growth of α-Fe2O3 crystals in the heterostructure with a conical-shaped surface. Meanwhile, the field emission scanning electron microscopy cross-section images confirm the formation of well-defined CuO layers under the α-Fe2O3 layers. The optical band gap energies for the heterostructures obtained were estimated from the diffuse reflectance spectra and ranged from 1.41 to 1.51 eV. Photoluminescence analysis revealed an improved separation and faster transfer of photogenerated electrons and holes for the heterostructures. The removal arsenic from an aqueous solution was achieved through the direct adsorption for As(III) and visible light oxidation to As(V). An enhancement of removal efficiency of As(III) for the heterostructures fabricated compared to pristine oxides was obtained. © 2020Fondo Nacional de Desarrollo Científico y Tecnológico - Fondecy
Rheological and textural properties of gluten-free doughs made from Andean grains
No full textThe objective of this research was to evaluate the rheological and textural properties of gluten-free doughs based on potato starch, which was partially substituted by different proportions of quinoa (10%, 30% and 50%), kiwicha (10%, 30% and 50%) or tarwi flour (10%, 20% and 30%). The influence of the substitution on the kinetics of the leavening process was studied as well. The back-extrusion technique was used to determine rheological and textural properties of the dough, and the leavening kinetics were modelled using the Gompertz equation. The results showed that textural properties such as firmness, consistency, cohesiveness and viscosity index, as well as the consistency index of the doughs increased as the level of substitution of the Andean grain flour in the formulation increased. It was determined that the formulations with an addition of 10% and 20% for quinoa or kiwicha flour, and 10% for tarwi flour would be most suitable for developing gluten-free breads. © 2020 The Authors. International Journal of Food Science & Technology published by John Wiley & Sons Ltd on behalf of Institute of Food, Science and Technology (IFSTTF)Fondo Nacional de Desarrollo Científico y Tecnológico - Fondecy
Projection of upwelling-favorable winds in the Peruvian upwelling system under the RCP8.5 scenario using a high-resolution regional model
No full textThe Peruvian upwelling system (PUS) is the most productive Eastern Boundary Upwelling System (EBUS) of the world ocean. Contrarily to higher latitude EBUSs, there is no consensus yet on the response of upwelling-favorable winds to regional climate change in this region. Global climate models are not able to reproduce the nearshore surface winds, and only a few downscaling studies have been performed by using relatively coarse-grid atmospheric models forced by idealized climate change scenarios. In the present study, the impact of climate change on the PUS upwelling-favorable winds was assessed using a high resolution regional atmospheric model to dynamically downscale the multi-model mean projection of an ensemble of 31 CMIP5 global models under the RCP8.5 worst-case climate scenario. We performed a 10-year retrospective simulation (1994–2003) forced by NCEP2 reanalysis data and a 10-year climate change simulation forced by a climate change forcing (i.e. differences between monthly-mean climatologies for 2080–2100 and 1989–2009) from CMIP5 ensemble added to NCEP2 data. We found that changes in the mean upwelling-favorable winds are weak (less than 0.2 m s?1). Seasonally, summer winds weakly decrease (by 0–5%) whereas winter winds weakly increase (by 0–10%), thus slightly reinforcing the seasonal cycle. A momentum balance shows that the wind changes are mainly driven by the alongshore pressure gradient, except in a local area north of the Paracas peninsula, downstream the main upwelling center, where wind increase in winter is driven by the shoreward advection of offshore momentum. Sensitivity experiments show that the north–south sea surface temperature gradient plays an important role in the wind response along the north and central coasts, superimposed onto the South Pacific Anticyclone large-scale forcing. A reduction (increase) of the gradient induces a wind weakening (strengthening) up to 15% (25%) off the northern coast during summer. This local mechanism is not well represented in global climate models projections, which underlines the strong need for dynamical downscaling of coastal wind in order to study the impact of climate change on the Peruvian upwelling ecosystem. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Evidence of nonlinear Walker circulation feedbacks on extreme El Nino Pacific diversity: Observations and CMIP5 models
No full textThe work was performed using computational resources, that is, the HPC-Linux-Cluster, at the Laboratorio de Dinamica de Fluidos Geofisicos Computacionales (http://scah.igp.gob.pe/laboratorios/dfgc) at Instituto Geofisico del Peru (grants 101-2014-FONDECYT).The Walker circulation (WC) is essential for the formation and diversity of El Nino events. However, the nonlinear WC feedback during extreme Central and Eastern El Nino episodes (C and E episodes, respectively) has received little attention. This study used observational datasets and the Atmospheric Model Intercomparison Project (AMIP) and historical simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Eight out of 21 historical models that simulate the El Nino-Southern Oscillation (ENSO) nonlinearity also simulate the nonlinear Bjerknes feedback in C and E episodes. The opposite does not necessarily occur. However, the underestimation of E might limit the empirical determination. Moreover, few historical models simulate the shallow conditional instability of the second kind (CISK) mechanism. Positive C episodes feature an eastward shift in the ascending branch of the Pacific Walker cell (PWC), while shallow convection prevails over the far-eastern Pacific (FEP). Positive E events feature two anomalous ascending branches located over the central-western Pacific (170 degrees W) and FEP (80 degrees W). Positive anomalies in sea surface temperature over the FEP induce the second ascending branch. The positive stratification anomaly in the central Pacific Ocean, which is associated with overestimated Ekman feedback, limits the eastward displacement of the first ascending branch of the PWC. The net surface heat flux determines the duration of growth of the two ascending branches of the PWC during C and E events. Because of their coarse resolution, the historical models underestimate the positive stratification anomaly in the FEP, causing the quick demise of the second ascending branch.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Morphological, genetic, and ecological differences among the low-latitude kelps Eisenia Cokeri and e. Gracilis
No full textConvenio de Cofinanciamiento N degrees 017-2016-FONDECyT, CONCYTEC; Inventario y Monitoreo de la Diversidad Biologica-IMARPE; UCSC Chile: DIN 22/2016; CIBAS-UCSC.[Abstract not available]Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Phenotypic Characterization of Fine-Aroma Cocoa from Northeastern Peru
No full textThe authors thank the Fondo Nacional de Desarrollo Cientifico, Tecnologico y de Innovacion Tecnologica (FONDECYT) for funding this research through the contract No 026-2016 of the Circulo de Investigacion para la Innovacion y el fortalecimiento de la cadena de valor del cacao nativo fino de aroma en la zona nor oriental del Peru-CINCACAO project, executed by the Instituto de Investigacion para el Desarrollo Sustentable de Ceja de Selva (INDES-CES).The phenotypic characterization of cacao (Theobroma cacao L.) plays an important role in the generation of information for the conservation of cacao germplasm. The objective of this study is to characterize phenotypically 146 ecotypes of fine-aroma native cacao (FFNC) from northeastern Peru that were collected from 280 to 1265 metres above sea level. Morphological descriptors of fruits and seeds, sensory characteristics, and productivity descriptors were used. The data obtained were analyzed using descriptive statistics with pie charts, distribution histograms, and multiple correspondence analysis. The results showed that 76.7% of the cocoa ecotypes had green immature fruits, 73% showed slight roughness on the surface of the fruit, 54% showed an intermediate thickness of the fruit wall, and 90% had the appearance of pairs of equidistant ridges. Regarding seed characteristics, 71% showed purplish cotyledons, with a high presence of floral and fruity notes and low levels of bitterness and astringency. Likewise, 52% of the fruits and 64% of the seeds were long. More importantly, cocoa beans needed to produce between 14 and 16 pods to obtain one kilogram of dry cocoa, which reflects a good level of productivity. Finally, there was a positive relationship between elevation levels and the presence of fine-flavoured native cocoa, i.e., the greatest diversity of native cocoa with floral and fruity notes was found above 501 metres above sea level.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Chemical composition and in vitro antiplasmodial activity of the total alkaloids of the bulbs of two amaryllidaceae species from Northern Peru
No full textWe thank the Fondo Nacional de Desarrollo Científico, Tecnológico y de Innovación Tecnológica (FONDECYT) del Consejo Nacional de Ciencia Tecnología e Innovación Tecnologica (CONCYTEC-Perú) Grants Nº 110 -2018 - FONDECYT, for financial support to this study. The authors thank the Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (CYTED) for providing the framework.Introduction: The amaryllidaceae family is characterized by presenting alkaloids with powerful pharmacological activities, including antiprotozoal activity. The aim of the present work was to determine the chemical composition and evaluate the in vitro antiplasmodial activity of the total alkaloids of the bulbs of two amaryllidaceae species from northern Perú. Methods: The total alkaloids were extracted from the bulbs using an acid-base extraction. The chemical composition of the total alkaloids was determined by GC-MS, using galantamine as a reference standard. It was investigated the in vitro antiplasmodial activity against Plasmodium falciparum FCR-3 strain (chloroquine-resistant). Results: 8 alkaloids were identified in the bulbs of Clinanthus incarnatus: lycorine, galanthamine, galanthine, vittatine/crinine, hippamine, 3-O-acetylpowelline, 11,12-dehydroanhydrolycorine, 1-O-acetyllycorine with values of 19.73; 14.99; 10.36; 10.22; 10.16; 10.14; 10.04; 9.85 µg GAL/100 mg of total alkaloid (TA) respectively and 6 alkaloids in the bulbs of Clinanthus ruber: lycorine, anhydrolycorine, 11,12-dehydroanhydrolycorine, 2,4-didehydro-2-dehydroxylycorine, 8-0-dimethylmaritidine, hippamine, with values of 70.2; 18; 4.15; 3.45; 6.8 and 0.1 µg GAL/100 mg TA respectively. The total alkaloids of the species of C. incarnatus and C. ruber at concentrations of 1.0; 2.5; 5.0; 10.0; 25.0 and 50.0 µg/ml presented inhibition percentages of 23.5 ± 0.46% to 94 ± 0.56% against P. falciparum with (p <0.05). They also presented IC50 0.375 µg/ml (C. incarnatus) and IC50 0.241 µg / ml (C. ruber). Conclusion: The main component of total alkaloids of the bulbs of two species was lycorine, in adittion, these species showed in vitro antiplasmoidal activity against Plasmodium falciparum FCR-3 strain at the doses tested. © 2021 Phcogj.Com. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Design considerations of solar-driven hydrogen production plants for residential applications
No full textThis work was supported by CONCYTEC-FONDECYT (Peru), contract N° 159-2020-FONDECYT and the Pontifical Catholic University of Peru.The objective of this work is to discuss design considerations related to the development of a stand-Alone photovoltaic driven hydrogen production and consumption system. The referred system is currently on the design-phase so this work describes in particular the associated design considerations, governing equations, schematics and the expected system efficiency. The system design requirements include the production of enough energy to power an average residence located in the Ica city, Peru. The system design has been divided in four subsystems, each one having its own design considerations and limitations, (i) power, hydrogen (ii) production, (iii) storage and (iv) consumption. Regarding the power subsystem, the required considerations to generate the maximum amount of solar energy in the minimum amount of space are presented. For hydrogen production, different electrolyzer related technologies have been accounted for; including proton exchange (PEM), alkaline (AEC) and polymer (PEC). Hydrogen and oxygen storages are a critical aspect in the full hydrogen chain production. Currently no single technology satisfies all of the criteria required. As such, present technologies and selection considerations are presented. For using the produced hydrogen, fuel cell stacks including PEM and solid oxide ones are assessed. Finally, the right the combination of current, voltage (including conversion from DC to a constant AC supply) and fuel utilization maximizing efficiency and power output is determined. © 2021 American Society of Mechanical Engineers (ASME). All rights reserved.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Fractional Sobolev space with Riemann–Liouville fractional derivative and application to a fractional concave–convex problem
No full textThis work was partially supported by CONCYTEC PERU, 379-2019-FONDECYT “ASPECTOS CUALITATIVOS DE ECUACIONES NO-LOCALES Y APLICACIONES”A new fractional function space EL?[a,b] with Riemann–Liouville fractional derivative and its related properties are established in this paper. Under this configuration, the following fractional concave–convex problem: xDb?(aDx?u)=?u?+up,in(a,b)B?(u)=0,in?(a,b)where ?? (0 , 1) , ?? (0 , 1) and p?(1,1+2?1-2?) if ??(0,12) and p? (1 , + ?) if ??(12,1). B?(u) represent the boundary condition of the problem which depend of the behavior of ?? (0 , 1) , that is: B?(u)={limx?a+aIx1-?u(x)=0,if??(0,12)u(a)=u(b)=0,if??(12,1).By using Ekeland’s variational principle and mountain pass theorem we show that the problem (0.1) at less has two nontrivial weak solutions. © 2021, Tusi Mathematical Research Group (TMRG).Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte