3.1 Estancias en cooperación internacional
URI permanente para esta colección
Examinar
Examinando 3.1 Estancias en cooperación internacional por browse.metadata.type "info:eu-repo/semantics/article"
Resultados por página
Opciones de clasificación
-
PublicaciónA new species of the genus Neotropiella Handschin, 1942 (Collembola: Neanuridae) from Peru(Pensoft Publishers, 2020)
;Palacios-Vargas J.G.Callohuari Y.T.Background: Neotropiella is a genus of springtails which can be of medium size (2 mm) or relatively long (5 mm). These springtails live in leaf litter, under the bark of dead trees or in decomposing wood, mainly in the Neotropical Region and are often collected by litter samples on Berlese funnels or by pitfall traps. Most species have been described, based on relatively few specimens and chaetotaxy of several species is incomplete. New information: A new species within Neotropiella was discovered in recent pitfall trap collections from Peru. Neotropiella peruana sp. n. was taxonomically treated and studied under both phase contrast and scanning electron microscopy. It is similar to N. insularis from Brazil, but smaller with only 4 mandibular teeth (vs. 5) and with well-developed unguis lateral teeth. Intraspecific variation of the new species is provided. We also present the first DNA barcodes for the genus. © 2020 Palacios-Vargas J, Callohuari Y. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. All Rights Reserved. -
PublicaciónBand-fluctuations model for the fundamental absorption of crystalline and amorphous semiconductors: A dimensionless joint density of states analysis(Institute of Physics Publishing, 2019)
;Guerra Torres, Jorge Andrés ;Tejada A. ;Töfflinger J.A. ;Grieseler R.Korte L.We develop a band-fluctuations model which describes the absorption coefficient in the fundamental absorption region for direct and indirect electronic transitions in disordered semiconductor materials. The model accurately describes both the Urbach tail and absorption edge regions observed in such materials near the mobility edge in a single equation with only three fitting parameters. An asymptotic analysis leads to the universally observed exponential tail below the bandgap energy and to the absorption edge model at zero Kelvin above it, for either direct or indirect electronic transitions. The latter feature allows the discrimination between the absorption edge and absorption tails, thus yielding more accurate bandgap values when fitting optical absorption data. We examine the general character of the model using a dimensionless joint density of states formalism with a quantitative analysis of a large amount of optical absorption data. Both heavily doped p-type GaAs and nano-crystalline Ga 1-x Mn x N, as examples for direct bandgap materials, as well as amorphous Si:H x , SiC:H x and SiN x , are modeled successfully with this approach. We contrast our model with previously reported empirical models, showing in our case a suitable absorption coefficient shape capable of describing various distinct materials while also maintaining the universality of the exponential absorption tail and absorption edge. © 2019 IOP Publishing Ltd. -
PublicaciónCALLISTO facilities in Peru: spectrometer commissioning and observations of type III solar radio bursts(NATL ASTRONOMICAL OBSERVATORIES, CHIN ACAD SCIENCES, 2021)
;Alonso Rengifo, Javier ;Loaiza-Tacuri, Veronica ;Bazo, JoseGuevara Day, Walter RobertThe Astrophysics Directorate of CONIDA has installed two radio spectrometer stations belonging to the e-CALLISTO network in Lima, Peru. Given their strategic location near the Equator, it is possible to observe the Sun evenly throughout the whole year. The receiver located at Pucusana, nearby the capital city of Lima, took data from October 2014 until August 2016 in the metric and decimetric bands looking for radio bursts. During this period, this e-CALLISTO detector was unique in its time-zone coverage. To asses the suitability of the sites and the performance of the antennas, we analyzed the radio ambient background and measured their radiation pattern and beamwidth. To demonstrate the capabilities of the facilities for studying solar dynamics in these radio frequencies, we have selected and analyzed type III Solar Radio Bursts. The study of this kind of burst helps to understand the electron beams traversing the solar corona and the solar atmospheric density. We have characterized the most common radio bursts with the following mean values: a negative drift rate of -25.8 +/- 3.7 MHz s(-1), a duration of 2.6 +/- 0.3 s and 35 MHz bandwidth in the frequency range of 114 to 174 MHz. In addition, for some events, it was possible to calculate a global frequency drift which on average was 0.4 +/- 0.1 MHz s(-1). -
PublicaciónCase Report: Possible Vertical Transmission of Bartonella bacilliformis in Peru(American Society of Tropical Medicine and Hygiene, 2015)
;Tuya, XL ;Escalante-Kanashiro, R ;Tinco, C ;Pons, MJ ;Petrozzi, V ;Ruiz, Jdel Valle, JA 22-day-old male was admitted with a 2-day history of irritability, dyspnea, jaundice, fever, and gastroin testinal bleeding. A thin blood smear was performed, which showed the presence of intraerythrocyte bacteria identified as Bartonella bacilliformis, and subsequently, the child was diagnosed with Carrion’s disease. The diagnosis was confirmed by specific polymerase chain reaction. The child was born in a non-endemic B. bacilliformis area and had not traveled to such an area before hospitalization. However, the mother was from an endemic B. bacilliformis area, and posterior physical examination showed the presence of a wart compatible with B. bacilliformis in semi-immune subjects.These data support vertical transmission of B. bacilliformis. -
PublicaciónCharacterization of Plukenetia volubilis L. fatty acid-based alkyd resins(Elsevier BV, 2020)
;Hadzich, Antonella ;Gross, G. Alexander ;Leimbach, Martin ;Ispas, Adriana ;Bund, AndreasFlores, SantiagoFatty acid-based alkyd resins prepared with different amounts of glycerol and pentaerythritol were characterized. Sacha inchi oil and linseed oil (comparative purposes) were used as fatty acids' sources. FT-IR and H-1 NMR spectroscopy were done for alkyd structural verification. Alkyd resins were evaluated through physico-chemical (colour, density, viscosity) and thermal characterization. Film coating performance (drying, hardness, chemical resistance) was also studied. The oxidative crosslinking time tendency was corroborated by the quartz crystal microbalance (QCM) technique. Alkyd resins obtained with fatty acids from sacha inchi and linseed oils had similar properties. Results indicated that lighter resins can be obtained from sacha inchi oil, whereas pentaerythritol increases viscosity and thermal stability, and retards drying time of fatty-acid based alkyd resins. -
PublicaciónCharacterization of two Achromobacter xylosoxidans isolates from patients with pertussis-like symptoms(Elsevier B.V., 2015)
;Orellana-Peralta, F ;Jacinto, M ;Pons, MJ ;Gomes, C ;Bada, C ;Reyes, I ;Mendoza, JDRuiz, JTo characterize two Achromobacter xylosoxidans recovered from 2 patients diagnosed with pertussis during a Bordetella pertussis surveillance program. -
PublicaciónChitosan films containing TiO2 nanoparticles modified with tungstophosphoric acid for the photobleaching of malachite green in solid-gas interfaces upon different wavelengths(Elsevier, 2018)
;Rengifo-Herrera J.A. ;Marín-Silva D.A. ;Mendoza-Portillo E. ;Pinotti A.N.Pizzio L.R.Chitosan (CS) films containing visible light absorbing TiO2 nanoparticles modified with tungstophosphoric acid (TPA-TiO2) at different TPA-TiO2:CS ratios (10%, 20%, 30% and 40% (w/w) called CS/TPA-TiO2-10, CS/TPA-TiO2-20, CS/TPA-TiO2-30, and CS/TPA-TiO2-40 respectively) were prepared. Films were characterized by DRS, SEM-EDS, XRD, ATR-FT-IR, and contact angle (CA). Materials were evaluated in malachite green (MG) photobleaching solid-gas interface reactions upon different wavelengths. -
PublicaciónCombinatorial approach toward optimization of the light emission intensity of AlOxNy:Yb3+ thin films(Optica Publishing Group, 2019)
;Tucto, KY ;Aponte, W ;Dulanto, JA ;Tofflinger, JA ;Guerra, JAGrieseler, RTo obtain an adequate luminescent emission, a significant effort must be made to find a suitable host material. An interesting and highly efficient method is a combinatorial approach, which allows high velocity screening of a wider range of properties. In the present work, a compositional gradient-based, thin-film library of 𝑎-AlOxNy:Yb3+ has been prepared by radio frequency co-sputtering from two targets. The ytterbium concentration range spreads from 0.9 to 4.2 at. % and the oxygen to nitrogen ratio from 0.6 to 3.6. Using different annealing temperatures, the activation energy of the rare earth ions and activation mechanisms can be evaluated. Finally, optimal elemental compositions in the investigated range are proposed. -
PublicaciónDetermination of the complex refractive index and optical bandgap of CH3NH3PbI3 thin films(AIP Publishing, 2017)
;Guerra, J. A. ;Tejada, A. ;Korte, L. ;Kegelmann, L. ;Tofflinger, J. A. ;Albrecht, S. ;Rech, B.Weingartner, R.We report the complex refractive index of methylammonium lead iodide (CH3NH3PbI3) perovskite thin films obtained by means of variable angle spectroscopic ellipsometry and transmittance/reflectance spectrophotometry in the wavelength range of 190 nm to 2500 nm. The film thickness and roughness layer thickness are determined by minimizing a global unbiased estimator in the region where the spectrophotometry and ellipsometry spectra overlap. We then determine the optical bandgap and Urbach energy from the absorption coefficient, by means of a fundamental absorption model based on band fluctuations in direct semiconductors. This model merges both the Urbach tail and the absorption edge regions in a single equation. In this way, we increase the fitting region and extend the conventional (αℏω)2-plot method to obtain accurate bandgap values. © 2017 Author(s). -
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)
;Torres C. ;Quispe R. ;Calderón N.Z. ;Eggert L. ;Hopfeld M. ;Rojas C. ;Camargo M.K. ;Bund A. ;Schaaf P.Grieseler R.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. -
PublicaciónEffect of impregnation solutions on the synthesis of Ni-Cu/Al2O3 catalyst to obtain carbon nanofibers(IOP Publishing, 2018)
;Almiron, J ;Alcazar, H ;Churata, R ;Roudet, F ;Ziouche, KChicot, DThe present work reports on the influence of nickel molar loading and impregnation solutions, nitrate salts and copper and nickel ammonium complexes, on the synthesis of Ni-Cu catalyst supported on alumina for obtaining carbon nanofibers by catalytic chemical vapor deposition of methane. These catalysts were characterized by N2 adsorption-desorption, x-ray Diffraction, Thermo-Gravimetric Analysis and Scanning Electron Microscopy for the carbon nanostructures analysis. -
PublicaciónEsterification and Characterization of Starch From Andean Tubers(Wiley, 2019)
;Velasquez-Barreto, FF ;Bello-Perez, LA ;Yee-Madeira, HSanchez, CEVStarch 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. -
PublicaciónEvaluation of the leishmanicidal activity of plants used by Peruvian Chayahuita ethnic group(Elsevier B.V., 2007)
;Estevez Y. ;Castillo D. ;Pisango M.T. ;Arevalo J. ;Rojas R. ;Alban J. ;Deharo E. ;Bourdy G.Sauvain M.Aim of the study: A total of 27 ethanolic plant extracts from 27 species were screened for leishmanicidal activity in vitro against Leishmania amazonensis. Most of the selected species (19) are traditionally used by the Chayahuitas, an Amazonian Peruvian ethnic group, to treat skin affections and/or leishmaniasis. -
PublicaciónFour new species of Aleiodes (Hymenoptera: Braconidae: Rogadinae) from the Neotropical Region(Cambridge University Press (CUP), 2017)
;Garro, Lidia Sulca ;Shimbori, Eduardo Mitio ;Penteado-Dias, Angelica MariaShaw, Scott RichardFour new species of the Aleiodes apicalis (Brulle) species group (Hymenoptera: Braconidae: Rogadinae) from the Neotropical Region are described and illustrated: Aleiodes ambrosiae new species. from Peru, A. aquilesi new species from Costa Rica, and A. sachambrosiae new species and A. tapirape new species from Brazil. We also add new distribution records for Aleiodes molestus Cresson, from Costa Rica. With the addition of the new species, the A. apicalis species group has 11 species from the New World, six of which are recorded from Neotropical Region. -
PublicaciónGenome sequence and analysis of the tuber crop potato(Springer Nature Limited, 2011)
;Xu X. ;Pan S. ;Cheng S. ;Zhang B. ;Mu D. ;Ni P. ;Zhang G. ;Yang S. ;Li R. ;Wang J. ;Orjeda G. ;Guzman F. ;Torres M. ;Lozano R. ;Ponce O. ;Martinez D. ;De La Cruz G. ;Chakrabarti S.K. ;Patil V.U. ;Skryabin G. ;Kuznetsov B.B. ;Ravin N.V. ;Kolganova T.V. ;Beletsky A.V. ;Mardanov A.V. ;Di Genova A. ;Bolser D.M. ;Martin D.M.A. ;Li G. ;Yang Y. ;Kuang H. ;Hu Q. ;Xiong X. ;Bishop G.J. ;Sagredo B. ;Mejía N. ;Zagorski W. ;Gromadka R. ;Gawor J. ;Szczesny P. ;Huang S. ;Zhang Z. ;Liang C. ;He J. ;Li Y. ;He Y. ;Xu J. ;Zhang Y. ;Xie B. ;Du Y. ;Qu D. ;Bonierbale M. ;Ghislain M. ;Herrera M.D.R. ;Giuliano G. ;Pietrella M. ;Perrotta G. ;Facella P. ;O'Brien K. ;Feingold S.E. ;Barreiro L.E. ;Massa G.A. ;Diambra L. ;Whitty B.R. ;Vaillancourt B. ;Lin H. ;Massa A.N. ;Geoffroy M. ;Lundback S. ;DellaPenna D. ;Buell C.R. ;Sharma S.K. ;Marshall D.F. ;Waugh R. ;Bryan G.J. ;Destefanis M. ;Nagy I. ;Milbourne D. ;Thomson S.J. ;Fiers M. ;Jacobs J.M.E. ;Nielsen K.L. ;Sønderkær M. ;Iovene M. ;Torres G.A. ;Jiang J. ;Veilleux R.E. ;Bachem C.W.B. ;De Boer J. ;Borm T. ;Kloosterman B. ;Van Eck H. ;Datema E. ;Hekkert B.L. ;Goverse A. ;Van Ham R.C.H.J.Visser R.G.F.Potato (Solanum tuberosum L.) is the world’s most important non-grain food crop and is central to global food security. It is clonally propagated, highly heterozygous, autotetraploid, and suffers acute inbreeding depression. Here we use a homozygous doubled-monoploid potato clone to sequence and assemble 86% of the 844-megabase genome. We predict 39,031 protein-coding genes and present evidence for at least two genome duplication events indicative of a palaeopolyploid origin. -
PublicaciónGenotypic Characterization of Enterotoxigenic Escherichia coli Strains Causing Traveler's Diarrhea(ASM Journals, 2013)
;Rivera, FP ;Medina, AM ;Aldasoro, E ;Sangil, A ;Gascon, J ;Ochoa, TJ ;Vila, JRuiz, JThis study aims to characterize the presence of virulence factors of enterotoxigenic Escherichia coli (ETEC) causing traveler's diarrhea. Among 52 ETEC isolates, the most common toxin type was STh, and the most frequent colonization factors (CFs) were CS21, CS6, and CS3. On the other hand, the nonclassical virulence factors EAST1 and EatA were frequently present. -
PublicaciónLarval supply of Peruvian scallop to the marine reserve of Lobos de Tierra Island: A modeling approach(Elsevier, 2019)
;Flores-Valiente J. ;Tam J. ;Brochier T. ;Colas F. ;Pecquerie L. ;Aguirre-Velarde A. ;Mendo J.Lett C.The Peruvian scallop (Argopecten purpuratus) is the second main contributor to the total catch of mollusks in Peru, after jumbo squid. There are two main scallop banks populations in northern Peru: Lobos de Tierra Island (LTI) and Sechura Bay (SB). Despite a continuous, intense relocation of seeds from LTI, the natural bank population still persists there. To understand this, we studied larval connectivity between LTI and SB using the first invertebrate larval transport biophysical model developed in the region. Larval local retention were 2.4% and 1.57% on average at LTI and SB respectively, while larval transport from SB to LTI was 0.02% on average and 0.07% in the opposite direction. Both larval retention and larval transport increased with spawning depth and were highest in austral summer. Two main larval transport paths from SB to LTI were identified, resulting from a combination of horizontal mesoscale circulation patterns and vertical flows. Potential management implications for these natural banks are discussed. -
PublicaciónLower thermal tolerance in nocturnal than in diurnal ants: a challenge for nocturnal ectotherms facing global warming(Blackwell Publishing Ltd, 2018)
;Garcia-Robledo C. ;Chuquillanqui H. ;Kuprewicz E.K.Escobar-Sarria F.This study explores differences in heat tolerance among diurnal and nocturnal ant species in four ecosystems in Mexico: tropical montane, tropical rainforest, subtropical dry forests, and high-elevation semi-desert. -
PublicaciónMolecular interaction of natural dye based on Zea mays and Bixa orellana with nanocrystalline TiO2 in dye sensitized solar cells(International Association of Physical Chemists, 2021)
;Huamán Aguirre, Arnold Anthony ;Quintana Cáceda, María EstherSalazar Salinas, KarimThis work studies the interaction between natural dyes obtained from Peruvian Zea mays and Bixa orellana seeds and nanostructured titanium dioxide, in order to evaluate their function as sensitizers into solar cell devices. The effective attachment of dyes to the TiO2 layer is corroborated by the comparison of UV-Visible absorption and FT-IR spectra of the extracted dye solutions and sensitized TiO2 electrodes. The principal compounds from the seed extraction of Zea mays and Bixa orellana are cyanidin-3-glucoside (C3G) and bixin respectively, which were analyzed in an isolated dye/cluster TiO2 system by molecular dynamic simulation. The results showed that chemisorption is carried out through a consecutive deprotonation process, and Ti-O bond formation by the monodentate OH and COOH anchoring groups, for C3G and bixin respectively. Finally, we tested the effect of the dye - TiO2 interaction on the charge transfer by the comparison of the current-voltage curves and incident photon-to-current conversion efficiency (IPCE) of the cells. We found that dye agglomeration in films with Bixa orellana and high charge recombination of films with Zea mays are critical points to be solved. For this reason, we propose the pretreatment of the TiO2 film before sensitization with Bixa orellana and analyze the effects of pH in Zea mays solution, in order to obtain better device efficiencies. -
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)
;Combey, Andy ;Tricoche, Agnes ;Audin, Laurence ;Gandreau, David ;Benavente Escobar, Carlos ;Bastante Abuhadba, Jose ;Tavera, HernandoAngel Rodriguez-Pascua, MiguelAs 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.