Origem das variações de cores das escórias do vulcão Sierra Negra das Ilhas Galápagos

Volcanic cinder, also known as scoria, is an extrusive igneous rock that forms when gas-rich magmas of basaltic or andesitic composition cool quickly. It is typically dark in color, ranging from black to red depending on its chemical composition. Sometimes fresh cinder samples show a variety of shiny metallic colors on its surface ranging from blue to gold to silver. The origin of these colors has remained unknown up to now. Cinder samples from an eruptive event occurred in October 2005 have been collected in the surroundings of the Sierra Negra volcano in the Galápagos Islands. The samples’ crystallographic structure, chemical composition, and surface morphology have been analyzed using X-Ray diffractometry (XRD), energy dispersive X-Ray spectroscopy (EDS) and a field gun emission scanning electron microscopy (SEM), respectively. Based on an extensive physical and chemical analysis, we were able to demonstrate that these colors are due to a light interference phenomenon. These results have a great potential to be used for a wide variety of purposes such as determining the temperature and composition of magma and evaluating volcanic samples for planetary studies.Las cenizas volcánicas, también conocidas como escorias, son una roca ígnea extrusiva que se forma cuando los magmas ricos en gas de composición basáltica o andesítica se enfrían rápidamente. Es típicamente de color oscuro, que va del negro al rojo dependiendo de su composición química. A veces las muestras de ceniza fresca muestran una variedad de colores metálicos brillantes en su superficie que van del azul al oro y a la plata, dependiendo de la orientación de la muestra. Hasta ahora, el origen de estos colores ha permanecido desconocido. Muestras de cenizas de un evento eruptivo ocurrido en octubre de 2005, han sido recogidas en los alrededores del volcán Sierra Negra en las Islas Galápagos. La estructura cristalográfica, la composición química y la morfología de la superficie de estas muestras se han analizado utilizando la difracción de rayos X (XRD), la espectroscopia de rayos X de dispersión de energía (EDS) y la microscopia electrónica de barrido con emisión de campo (SEM), respectivamente. Basándonos en un extenso análisis físico y químico, hemos podido demostrar que estos colores se deben a un fenómeno de interferencia de la luz. Estos resultados tienen un gran potencial para ser utilizados para una amplia variedad de propósitos como la determinación de la temperatura y la composición del magma, así como la evaluación de muestras volcánicas para estudios planetarios.As cinzas vulcânicas, também conhecidas como escórias, são uma rocha ígnea extrusiva formada quando os magmas ricos em gás de composição basáltica ou andesítico esfriam rapidamente. É tipicamente de cor escura, que vai do preto ao vermelho, dependendo de sua composição química. Às vezes as amostras de cinza fresca mostram uma variedade de cores metálicas brilhantes em sua superfície que vão do azul ao ouro e à cor prata, dependendo da orientação da amostra. Até o momento, a origem destas cores permanece desconhecida. Amostras de cinzas de um evento eruptivo ocorrido em outubro de 2005, foram recolhidas nos arredores do vulcão Sierra Negra nas Ilhas Galápagos. A estrutura cristalográfica, a composição química e a morfologia da superfície destas amostras foram analisadas por meio da difração de raios X (XRD), da espectroscopia de raios X por energia dispersiva (EDS) e da microscopia eletrônica de varredura com emissão de campo (SEM), respectivamente. Com base em uma extensa análise física e química, pudemos demonstrar que essas cores se devem a um fenômeno de interferência da luz. Esses resultados têm um grande potencial para serem utilizados com uma ampla variedade de propósitos como a determinação da temperatura e a composição do magma, bem como a avaliação de amostras vulcânicas para estudos planetários

Análisis de datos de exceso de mortalidad por infecciones y muertes por COVID-19 en Ecuador

The global COVID-19 pandemic has shocked the world. Since the virus gave rise to health problems and often ended in deaths, the count of the contagion and the deceased has been an open issue. Such statistics are vital for every nation and even every city or district and suburb as these numbers decide the level of intervention and the subsequent reduction of its given spread. Worldwide data show a mortality rate of around two percent prior to successful vaccination campaigns. However, Ecuador's statistical data indicate an abnormal amount of excess mortality, which is officially denied in each of the studied countries. These numbers have been projected on a monthly basis and exceed up to 300% of the official COVID-19 deaths. In particular, the average mortality rate in Ecuador, prior to and close to the pandemic, has been about 6083.4±234.6, while in the worst month during the sanitary crisis, deaths piled up to 21,000 people, and only 1180 were recognized as deceased by COVID-19. The reasons are widespread but based on an insufficient financed health sector, political incompetence, lack of leadership, and a long-lasting economic crisis. Therefore, premature endings of confinements or lockdowns have contributed to an accelerated contagion and seem to even counteract the vaccination phase, in middle 2021, shortly before excess mortality ceased completely.La pandemia mundial de COVID-19 ha conmocionado al mundo. Dado que el virus dio lugar a problemas de salud y, a menudo, terminó en muertes, el recuento del contagio y de fallecimientos ha sido un tema abierto. Estas estadísticas son vitales para cada nación e incluso para cada ciudad o distrito y suburbio, ya que estos números deciden el nivel de intervención y la consiguiente reducción de su extensión dada. Los datos mundiales indican una tasa de mortalidad de alrededor del dos por ciento antes de campañas de vacunación exitosas. Sin embargo, los datos estadísticos de Ecuador indican una cantidad anormal de exceso de mortalidad, que oficialmente se niega en cada uno de los países estudiados. Estas cifras se han proyectado mensualmente y superan hasta el 300 % de las muertes oficiales por COVID-19. En particular, en Ecuador la tasa de mortalidad promedio antes y cerca de la pandemia ha sido de alrededor de 6 083,4 ± 234,6, mientras que en el peor mes de la crisis sanitaria, las muertes ascendieron a 21 mil personas, pero solo se reconocieron 1 180 como personas fallecidas por COVID-19 o con este. Las razones son generalizadas, pero se basan en un sector de salud insuficientemente financiado, incompetencia política, falta de liderazgo y una crisis económica de larga duración. Por lo tanto, las terminaciones prematuras de los confinamientos o encierros han contribuido a un contagio acelerado y parecen incluso contrarrestar la fase de vacunación, a mediados de 2021, poco antes de que el exceso de mortalidad cesara por completo

Virus diagnosis in tree tomato (iSolanum betaceum/i Cav.) by RT-PCR and transmission electron microscopy in Pichincha and Tungurahua Provinces of Ecuador

Tree tomato (Solanum betaceum Cav.) is an economically important fruit crop in Ecuador. The symptoms of higher virus-related incidence in plantations located in Pichincha and Tungurahua correspond to yellowing, mosaic, leaf deformation and blistering. This research carried out a diagnosis of the viruses present in these production areas using molecular techniques (RT-PCR) and electron microscopy. The identified viruses belonged to the genera Potyvirus (Potato virus Y; PVY), Polerovirus (Potato leaf roll virus; PLRV) and Tobamovirus (Tomato mosaic virus; ToMV), constituting a viral complex of at least two of the three viruses found. The symptomatology related to PVY was spots with tan or oily appearance and leaf  deformation; in addition to these symptoms, yellowing and chlorosis were related to PLRV. Foliar blistering was related to the occurrence of the three viruses. The results indicated the presence of the three viruses in Tumbaco (Pichincha) and two (PLRV and PVY) in Pelileo (Tungurahua). PLRV was found in the 100% of the total samples, PVY in 50% of the Pelileo’s samples and ToMV only in Tumbaco. ToMV virus has been detected for the first time infecting tree tomato in Ecuador

Ascorbic Acid-assisted Green Synthesis of Silver Nanoparticles: pH and Stability Study

In this chapter, eco-friendly in situ synthesis of silver nanoparticles (AgNPs) using a mixture of ascorbic acid and citric acid is introduced. The synthesis conditions of the AgNPs were optimized by adjusting the pH of the reaction mixture. Different spectroscopic and microscopic techniques have been used to characterize the physico-chemical properties of AgNPs. The synthesis of AgNPs was primarily identified by the appearance of yellow colour and confirmed by showing λmax = 409 nm in UV-visible spectroscopy. All characterization techniques reveal that the generated AgNPs were non-aggregated, quasi-spherical shapes with an average size of 22.4 ± 13.2 nm, and face-centred cubic crystalline structures. Infrared spectroscopy confirms the surface of AgNPs covered with -COOH group and shows peaks at 1733, 1759, 3262 and 3633 cm−1. Moreover, synthesized AgNPs at pH 10 were stable for one month with a slight change in size. A straightforward, facile and environmentally-friendly synthesis of highly stable AgNPs may contribute to future engineering applications

Sonochemical Synthesis of Silver Nanoparticles Using Starch: A Comparison

A novel approach was applied to synthesize silver nanoparticles using starch under sonication. Colloidal silver nanoparticles solution exhibited an increase of absorption from 420 to 440 nm with increase starch quantity. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, amorphous, silver nanoparticles of diameter ranging from 23 to 97 nm with mean particle size of 45.6 nm. Selected area electron diffraction (SAED) confirmed partial crystalline and amorphous nature of silver nanoparticles. Silver nanoparticles synthesized in this manner can be used for synthesis of 2-aryl substituted benzimidazoles which have numerous biomedical applications. The optimized reaction conditions include 10 ml of 1 mM AgNO3, 25 mg starch, 11 pH range, and sonication for 20 min at room temperature

Tailoring Organic-Organic Poly(vinylpyrrolidone) Microparticles and Fibers with Multiwalled Carbon Nanotubes for Reinforced Composites

Polymeric-based microparticles and fibers are tailorable for a wide range of common industrial and biomedical applications, while multiwalled carbon nanotubes (MWCNTs) are among the most useful macromolecules based on their outstanding electronic, mechanical, and optical properties at the nanoscale. If one combines these nanostructures with various polymeric precursors, their range of potential applications becomes even greater. One of the simplest and most affordable methods for fabricating micro- and nanostructures is electrospinning. Herein we demonstrate how MWCNTs may be used to produce tailor-made organic-organic poly(vinylpyrrolidone) (PVP) microparticles and fibers via electrospinning by studying their structural, vibrational, rheological, and mechanical properties' dependence on their solvent (ethanol (EtOH) or dimethylformamide (DMF)) and resulting morphology. Specifically, we find clear differences in morphologies from perfectly spherical and isolated microparticles to fibers mats, or a combination of fibers with entangled beads, with solvent type and concentration. On the basis of our findings, we propose that the mechanism governing the shape and size of the particles is a competition between the solvent's surface tension, dielectric constant, and viscoelastic properties. We show, based on both our experimental results and density functional theory (DFT) calculations, that OH functionalization of the MWCNTs is essential for achieving high PVP coverages and promoting the stability of the resulting PVP/MWCNT nanocomposite. Finally, by fabricating PVP/MWCNT fiber mats, we demonstrate that low concentrations (0.01-0.1 wt %) of MWCNTs led to a qualitative improvement (â250%) in the resulting mechanical properties, i.e., a reinforced composite. These results show how by controlling the solvent's dielectric constant, surface tension, and polymer concentration, one may produce tailor-made polymeric nanomaterials in combination with other organic/inorganic nanoparticles, i.e., silver, gold, or carbon allotropes, for next-generation applications

Simple Microcontact Printing Technique to Obtain Cell Patterns by Lithography Using Grayscale, Photopolymer Flexographic Mold, and PDMS

Microcontact printing using PDMS embossing tools and its variations have aroused the interest of a wide spectrum of research fields, hence the feasibility of defining micro and nanoscale patterns. In this work, we have proposed and demonstrated a novel lithography method based on grayscale patterns printed in a flexographic photopolymer mold and transferred to epoxy resin and a single PDMS stamp to obtain different microprint pattern structures. The geometry of the patterns can be modified by adjusting the layout and grayscale of the stamp patterns. The functionality of this contact printing methodology was validated by generating human induced pluripotent stem cells (hiPSC) patterns. These specific micropatterns can be very useful for achieving complex differentiation in cell lines such as hiPSC. Microfabrication through the new technique provides a promising alternative to conventional lithography for constructing complex aligned surfaces; these structures could be used as components of biological patterns or microfluidic devices.Fil: Gimenez, Rocio. Universidad Tecnológica Nacional; ArgentinaFil: Pérez Sosa, Camilo José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Bourguignon, Natalia. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Miriuka, Santiago Gabriel. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bhansali, Shekhar. University of Florida; Estados UnidosFil: Arroyo, Carlos R.. Universidad de Las Fuerzas Armadas; EcuadorFil: Debut, Alexis. Universidad de Las Fuerzas Armadas; EcuadorFil: Lerner, Betiana. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Perez, Maximiliano Sebastian. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Fertility and Iron Bioaccumulation in Drosophila melanogaster Fed with Magnetite Nanoparticles Using a Validated Method

Research on nanomaterial exposure-related health risks is still quite limited; this includes standardizing methods for measuring metals in living organisms. Thus, this study validated an atomic absorption spectrophotometry method to determine fertility and bioaccumulated iron content in Drosophila melanogaster flies after feeding them magnetite nanoparticles (Fe3O4NPs) dosed in a culture medium (100, 250, 500, and 1000 mg kg−1). Some NPs were also coated with chitosan to compare iron assimilation. Considering both accuracy and precision, results showed the method was optimal for concentrations greater than 20 mg L−1. Recovery values were considered optimum within the 95–105% range. Regarding fertility, offspring for each coated and non-coated NPs concentration decreased in relation to the control group. Flies exposed to 100 mg L−1 of coated NPs presented the lowest fertility level and highest bioaccumulation factor. Despite an association between iron bioaccumulation and NPs concentration, the 500 mg L−1 dose of coated and non-coated NPs showed similar iron concentrations to those of the control group. Thus, Drosophila flies’ fertility decreased after NPs exposure, while iron bioaccumulation was related to NPs concentration and coating. We determined this method can overcome sample limitations and biological matrix-associated heterogeneity, thus allowing for bioaccumulated iron detection regardless of exposure to coated or non-coated magnetite NPs, meaning this protocol could be applicable with any type of iron NPs.Fil: Pilaquinga, Fernanda. Pontificia Universidad Católica del Ecuador; EcuadorFil: Cardenas Alcoser, Elena Sofia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Gobierno de la Ciudad de Buenos Aires. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Fundación de Endocrinología Infantil. Centro de Investigaciones Endocrinológicas "Dr. César Bergada"; Argentina. Pontificia Universidad Católica del Ecuador; EcuadorFil: Vela, Doris. Pontificia Universidad Católica del Ecuador; EcuadorFil: Jara, Eliza. Pontificia Universidad Católica del Ecuador; EcuadorFil: Morey, Jeroni. University of the Balearic Islands; EspañaFil: Gutiérrez Coronado, José Luis. Universidad Autónoma de Madrid; EspañaFil: Debut, Alexis. Universidad de Las Fuerzas Armadas; EcuadorFil: Piña, María de las Nieves. University of the Balearic Islands; Españ

Regeneración de convertidores catalíticos usados a partir de desechos de vehículos a gasolina

Se estudiaron dos convertidores catalíticos comerciales de desecho (CCU y CCA) mediante las técnicas de oxidación a temperatura programada (TPO), reducción a temperatura programada (TPR), microscopia electrónica de barrido (SEM) y espectroscopia de dispersión de energía de rayos X (EDS). La microscopia electrónica de barrido mostró para los convertidores CCU y CCA una morfología de las partículas en esferas uniformes de 0,05 y 1,5 de µm e irregulares de 2 µm. Los resultados del análisis elemental mediante la técnica de EDS mostraron para el convertidor CCU la presencia de metales nobles como platino, paladio (Pt, Pd) y de hierro (Fe) como fase activa; asimismo, se evidencia óxido de fósforo (P2O4), óxido de cromo (Cr2O3) y óxido de calcio (CaO) como promotores. Por el contrario, el convertidor CCA presentó como fase activa metales nobles de Pt, Pd y Rh y, como promotores óxido de manganeso (MnO2), óxido de bario (BaO), zirconia (ZrO2) y ceria (CeO2). Los resultados de oxidación a temperatura programada (TPO) mostraron mediante el consumo de oxígeno de la formación de las especies oxídicas y el posterior tratamiento de reducción a temperatura programada (TPR) evidenciaron la recuperación de la reducción de las especies metálicas de Pt, Pd, Rh y Fe (fase activa) presentes en los convertidores catalíticos. Este hecho demostró la factibilidad técnica de recuperación de la fase actividad de la superficie metálica reducida en los convertidores catalíticos comerciales usados de desecho, para su reúso en automóviles de combustión interna a gasolina, para mitigar los efectos de contaminación de los gases de emisión.            Two used commercial waste catalytic converters (CCU and CCA) were studied using the programmed temperature oxidation technique (TPO), temperature-programmed reduction (TPR), scanning electron microscopy (SEM), and energy dispersion spectroscopy of X-ray (EDS). The scanning electron microscopy showed the CCU and CCA converters of the morphology of the particles in uniform spheres of 0.05 and 1.5 µm and irregular of 2 µm. The results of the elemental analysis using the EDS technique showed for the CCU converter the presence of the noble metals platinum, palladium (Pt, Pd), and iron (Fe) as an active phase, and phosphorus oxide (P2O4), chromium oxide (Cr2O3) and calcium oxide (CaO) as promoters. On the contrary, the CCA converter presented as an active phase noble metals of Pt, Pd, and Rh and as promoters manganese oxide (MnO2), barium oxide (BaO), zirconia (ZrO2), and ceria (CeO2). The oxidation results at programmed temperature (TPO) showed the consumption of oxygen through the formation of the oxide species, and the subsequent reduction treatment at programmed temperature (TPR) showed the recovery of the reduction of the metallic species of Pt, Pd, Rh, and Fe (active phase) present in catalytic converters. This fact demonstrated the technical feasibility of recovering the activity phase of the reduced metallic surface in used commercial catalytic converters from waste for its re-use in gasoline internal combustion automobiles from mitigating the effects of pollution of emission gases. &nbsp

Cost-effective fabrication of photopolymer molds with multi-level microstructures for pdms microfluidic device manufacture

This paper describes a methodology of photopolymer mold fabrication with multi-level microstructures for polydimethylsiloxane (PDMS) microfluidic device manufacture. Multi-level microstructures can be performed by varying UVA exposure time and channel width. Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and profilometry techniques have been employed to characterize the molds. Multiple molds with multi-level microstructures can be formed in a unique piece. Overall height/depth of the structures reaches up to 677 μm and a minimum of 21 μm. The method provides several advantages such as reduction of fabrication time, multiple structures with diverse topologies, a great variety of depth and height in a single mold and low cost of fabrication. The effectiveness of multi-level microstructure fabrication was evaluated by constructing PDMS microfluidic devices for cell culture and proliferation.Fil: Olmos Carreno, Carol Maritza. Universidad Tecnológica Nacional. Facultad Regional Haedo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Penãherrera, Ana. Universidad Tecnológica Nacional. Facultad Regional Haedo; Argentina. Albert Ludwigs University of Freiburg; AlemaniaFil: Rosero Yánez, Gustavo Ivan. Universidad Tecnológica Nacional. Facultad Regional Haedo; Argentina. Albert Ludwigs University of Freiburg; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vizuete, Karla. Universidad de Las Fuerzas Armadas; EcuadorFil: Ruarte, Darío. Albert Ludwigs University of Freiburg; AlemaniaFil: Follo, Marie. Albert Ludwigs University of Freiburg; AlemaniaFil: Vaca Mora, Andrea Vanessa. Universidad Tecnológica Nacional. Facultad Regional Haedo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arroyo, Carlos R.. Universidad de Las Fuerzas Armadas; EcuadorFil: Debut, Alexis. Universidad de Las Fuerzas Armadas; EcuadorFil: Cumbal Flores, Luis. Universidad de Las Fuerzas Armadas; EcuadorFil: Perez, Maximiliano Sebastian. Universidad Tecnológica Nacional. Facultad Regional Haedo; Argentina. Florida International University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lerner, Betiana. Universidad Tecnológica Nacional. Facultad Regional Haedo; Argentina. Florida International University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mertelsmann, Roland. Albert Ludwigs University of Freiburg; Alemani