Tasa de erosión y edades relativas de los conos monogenéticos de los campos volcánicos Auca Mahuida y Río Colorado basado en morfometría volcánica

La altura del cono, la relación altura/diámetro y la pendiente de un cono de escorias disminuyendurante los procesos de degradación con el tiempo y este concepto constituye la base para la dataciónrelativa de los conos. Disponiendo de dataciones absolutas se pueden calcular tasas de erosión yedades relativas. El objetivo de este trabajo consiste en datar en forma relativa los conosmonogenéticos de escoria ubicados en los campos volcánicos del Río Colorado y Auca Mahuida (Fig.1A), al sur de la región de Payenia.Utilizando el programa Global Mapper 12 se tomaron las medidas de parámetros morfológicos delos conos tales como perímetro de la base y del cráter, delineados sobre imágenes Bing y GoogleEarth®. A partir de las medidas se calcularon los diámetros respectivos (Dco y Dcr), alturas máximas ymínimas, a partir de las cuales se calcularon la altura promedio del cono (Hco), la pendiente promediode las laderas (Pco) y el volumen de los conos (Vco), dirección de elongación del cono y dirección deaportillamiento. Las medidas se realizaron sobre imágenes TanDEM-X que presentan una resolución de12 m con precisión relativa de alturas de 2 metros, cedidas para este estudio por el Centro AeroespacialAlemán (DLR). El tratamiento estadístico de los datos se realizó con los programas Excel 2016, SigmaPlot 10.0. y Stereonet online.Se midieron 44 conos relativamente bien conservados. Los Dc o de conos de escoria varían entre293 y 1682 m, con una mediana de 584 m y un promedio de 651 metros. Los Dcr varían entre 124 y 523m, con una mediana de 279 m y un promedio de 275 metros. La altura de los conos se encuentra en elrango 5-101m, con una mediana de 26 m y un promedio de 33 metros. Los volúmenes de los conos deescoria varían entre 3,5x106 y 7,2x106 m3, la mediana es 1x105 m3 y el promedio de los volúmenes es4,7x107 metros cúbicos. El rango de las pendientes de los conos es de 2°-15°, con una mediana de 9,7° yun promedio de 9,4°. Los rumbos de elongación dominantes de la base del cono se encuentran en ladirección Este-Oeste (Fig.1B). Esta dirección es indicadora, de acuerdo con Paulsen y Wilson (2010),del campo de esfuerzos en la comarca, que establece la expresión supericial de la orientación de losdiques alimentadores. Ello es compatible con la estructuraeste-oeste observable aproximadamente 20km al ESE del volcán Auca Mahuida y que habría constituido una isura eruptiva. Se observan dosdirecciones preferenciales de aportillamiento (Fig.1C), una en 85° coincidente con la dirección dedebilidad estructural del basamento y la otra en 275°, que representa la dirección de los vientospredominantes, los que inluyen en la construcción del ediicio volcánico, más delgado y propenso aerosión a barlovento. Se graicaron las relaciones de Hco en función del Dc o conjuntamente con larelación Hco=0,2Dco, estimada por Settle (1979) para un cono ideal no degradado (Fig. 1D). Todos losconos medidos graican por debajo de esta recta, indicandoun avanzado estado de erosión. Ladesviación delos datos respecto a la recta de Settle (1979) permite estimarsu edad relativa. Se graicótambién la Pc o contra lasedades absolutas (Fig.1E) disponibles para la zona. De todas las edadesrecopiladas, sólo cuatro corresponden a los conos medidos. De este gráico se obtuvo una tasa deerosión de 5° por Ma, un poco menor que la calculada para otras localidades de la Patagonia. A partir dela ecuación de la recta de la figura 1E se calcularon las edades morfológicas de los conos restantes, cuyafrecuencia está representada en el histograma de la igura 1F, donde se pueden apreciar cincoagrupamientos de edades relativas. El primero, el más antiguo entre 3,0 y 2,0 Ma puede correlacionarsecon las edades aportadas por Linares (1979) en Ramos y Barbieri (1988). El segundo, entre 2,0 y 1,5 Macomprende las fases volcánicas 1, 2 y 3 de Pallares et al. (2016). El tercer agrupamiento, entre 1,5 y 1,0Ma coincide con la quinta fase volcánica de Pallares et al. (2016). El cuarto (el más frecuente) y elquinto agrupamiento de edades morfológicas (<1,0 Ma) se correlacionan con las edades absolutas másjóvenes del campo volcánico del Río Colorado (Gudnason et al. 2012).El estudio morfométrico de los conos de escoria de los campos volcánicos Auca Mahuida y RíoColorado permitió establecer que un cono de escorias promedio tiene una altura de 26 m, un diámetrobasal de 651 m, un diámetro de cráter de 275 m y un volumen medio de 7,2x106 metros cúbicos. La pendiente promedio de los faldeos de los conos volcánicos es de 9,4°.Los faldeos de los conosvolcánicos se degradan a razón de 5° cada millón de años.Fil: Haller, Miguel Jorge F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Massaferro, Gabriela Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Alric, Viviana Ines. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Sayavedra, Sebastián. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaSéptimo Congreso Argentino de Geomorfología y Geología del CuaternarioPuerto MadrynArgentinaAsociación Argentina de Cuaternario y GeomorfologíaConsejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónic

Morfometría de los campos volcánicos cuaternarios de Payenia

La provincia volcánica de Payenia, ubicada en el retroarco de la Zona Volcánica Sur de los Andes, comprende los campos volcánicos Diamante, Nevado, Llancanelo, Payún Matrú, Tromen, Chachahuén y Auca Mahuida. Esta gran provincia eruptiva ha sido el resultado de un volcanismo basáltico cuya edad se encuentra comprendida entre los 2 Ma y el Holoceno (Folguera et al., 2009, entre otros). Los diferentes campos que la componen se caracterizan por la presencia de numerosos conos monogenéticos de composición básica, que son óptimos para la aplicación de métodos de morfometría para analizar la historia erosiva de los mismos.Fil: Massaferro, Gabriela Isabel. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; ArgentinaFil: Haller, Miguel Jorge F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Alric, V. I.. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Sayavedra, Sebastián. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaVII Jornadas de las Ciencias de la Tierra Dr. Eduardo MusacchioComodoro RivadaviaArgentinaUniversidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales y Ciencias de la Salud. Departamento de Geologí

A new way of valorizing biomaterials: the use of sunflower protein for 1 a-tocopherol microencapsulation

Biopolymer based microparticles were efficiently prepared from sunflower protein (SP) wall material and a-tocopherol (T) active core using a spray-drying technique. Protein enzymatic hydrolysis and/or N-acylation were carried out to make some structural modifications to the vegetable protein. Native and hydrolyzed SP were characterized by Asymmetrical Flow Field-Flow Fractionation (AsFlFFF). Results of AsFlFFF confirmed that size of proteinic macromolecules was influenced by degree of hydrolysis. The effect of protein modifications and the influence of wall/core ratio on both emulsions and microparticle properties were evaluated. Concerning emulsion properties, enzymatic hydrolysis involved a decrease in viscosity, whereas acylation did not significantly affect emulsion droplet size and viscosity. Microparticles obtained with hydrolyzed SP wall material showed lower retention efficiency (RE) than native SP microparticles (62-80% and 93% respectively). Conversely, acylation of both hydrolyzed SP and native SP allowed a higher RE to be reached (up to 100%). Increasing T concentration increased emulsion viscosity, emulsion droplet size, microparticle size, and enhanced RE. These results demonstrated the feasibility of high loaded (up to 79.2% T) microparticles

Cancer-selective, single agent chemoradiosensitising gold nanoparticles

Two nanometre gold nanoparticles (AuNPs), bearing sugar moieties and/or thiol-polyethylene glycol-amine (PEG-amine), were synthesised and evaluated for their in vitro toxicity and ability to radiosensitise cells with 220 kV and 6 MV X-rays, using four cell lines representing normal and cancerous skin and breast tissues. Acute 3 h exposure of cells to AuNPs, bearing PEG-amine only or a 50:50 ratio of alpha-galactose derivative and PEG-amine resulted in selective uptake and toxicity towards cancer cells at unprecedentedly low nanomolar concentrations. Chemotoxicity was prevented by co-administration of N-acetyl cysteine antioxidant, or partially prevented by the caspase inhibitor Z-VAD-FMK. In addition to their intrinsic cancer-selective chemotoxicity, these AuNPs acted as radiosensitisers in combination with 220 kV or 6 MV X-rays. The ability of AuNPs bearing simple ligands to act as cancer-selective chemoradiosensitisers at low concentrations is a novel discovery that holds great promise in developing low-cost cancer nanotherapeutics

Gut microbiota-derived propionate reduces cancer cell proliferation in the liver

Peer reviewedPublisher PD

Investigation of the Hemodynamic Effect of Stent Wires on Renal Arteries in Patients with Abdominal Aortic Aneurysms Treated with Suprarenal Stent-Grafts

The purpose of the study was to investigate the hemodynamic effect of stent struts (wires) on renal arteries in patients with abdominal aortic aneurysms (AAAs) treated with suprarenal stent-grafts. Two sample patients with AAA undergoing multislice CT angiography pre- and postsuprarenal fixation of stent-grafts were selected for inclusion in the study. Eight juxtarenal models focusing on the renal arteries were generated from the multislice CT datasets. Four types of configurations of stent wires crossing the renal artery ostium were simulated in the segmented aorta models: a single wire crossing centrally, a single wire crossing peripherally, a V-shaped wire crossing centrally, and multiple wires crossing peripherally. The blood flow pattern, flow velocity, wall pressure, and wall shear stress at the renal arteries pre- and post-stent-grafting were analyzed and compared using a two-way fluid structure interaction analysis. The stent wire thickness was simulated with a diameter of 0.4, 1.0, and 2.0 mm, and hemodynamic analysis was performed at different cardiac cycles. The interference of stent wires with renal blood flow was mainly determined by the thickness of stent wires and the type of configuration of stent wires crossing the renal ostium. The flow velocity was reduced by 20–30% in most of the situations when the stent wire thickness increased to 1.0 and 2.0 mm. Of the four types of configuration, the single wire crossing centrally resulted in the highest reduction of flow velocity, ranging from 21% to 28.9% among three different wire thicknesses. Wall shear stress was also dependent on the wire thickness, which decreased significantly when the wire thickness reached 1.0 and 2.0 mm. In conclusion, our preliminary study showed that the hemodynamic effect of suprarenal stent wires in patients with AAA treated with suprarenal stent-grafts was determined by the thickness of suprarenal stent wires. Research findings in our study are useful for follow-up of patients treated with suprarenal stent-grafts to ensure long-term safety of the suprarenal fixation

Generic Delivery of Payload of Nanoparticles Intracellularly via Hybrid Polymer Capsules for Bioimaging Applications

Towards the goal of development of a generic nanomaterial delivery system and delivery of the ‘as prepared’ nanoparticles without ‘further surface modification’ in a generic way, we have fabricated a hybrid polymer capsule as a delivery vehicle in which nanoparticles are loaded within their cavity. To this end, a generic approach to prepare nanomaterials-loaded polyelectrolyte multilayered (PEM) capsules has been reported, where polystyrene sulfonate (PSS)/polyallylamine hydrochloride (PAH) polymer capsules were employed as nano/microreactors to synthesize variety of nanomaterials (metal nanoparticles; lanthanide doped inorganic nanoparticles; gadolinium based nanoparticles, cadmium based nanoparticles; different shapes of nanoparticles; co-loading of two types of nanoparticles) in their hollow cavity. These nanoparticles-loaded capsules were employed to demonstrate generic delivery of payload of nanoparticles intracellularly (HeLa cells), without the need of individual nanoparticle surface modification. Validation of intracellular internalization of nanoparticles-loaded capsules by HeLa cells was ascertained by confocal laser scanning microscopy. The green emission from Tb3+ was observed after internalization of LaF3:Tb3+(5%) nanoparticles-loaded capsules by HeLa cells, which suggests that nanoparticles in hybrid capsules retain their functionality within the cells. In vitro cytotoxicity studies of these nanoparticles-loaded capsules showed less/no cytotoxicity in comparison to blank capsules or untreated cells, thus offering a way of evading direct contact of nanoparticles with cells because of the presence of biocompatible polymeric shell of capsules. The proposed hybrid delivery system can be potentially developed to avoid a series of biological barriers and deliver multiple cargoes (both simultaneous and individual delivery) without the need of individual cargo design/modification

Photosynthetic growth despite a broken Q-cycle

Central in respiration or photosynthesis, the cytochrome bc1 and b6f complexes are regarded as functionally similar quinol oxidoreductases. They both catalyse a redox loop, the Q-cycle, which couples electron and proton transfer. This loop involves a bifurcated electron transfer step considered as being mechanistically mandatory, making the Q-cycle indispensable for growth. Attempts to falsify this paradigm in the case of cytochrome bc1 have failed. The rapid proteolytic degradation of b6f complexes bearing mutations aimed at hindering the Q-cycle has precluded so far the experimental assessment of this model in the photosynthetic chain. Here we combine mutations in Chlamydomonas that inactivate the redox loop but preserve high accumulation levels of b6f complexes. The oxidoreductase activity of these crippled complexes is sufficient to sustain photosynthetic growth, which demonstrates that the Q-cycle is dispensable for oxygenic photosynthesis

Cryo-EM structure of the spinach cytochrome b6 f complex at 3.6 Å resolution.

The cytochrome b6 f (cytb6 f ) complex has a central role in oxygenic photosynthesis, linking electron transfer between photosystems I and II and converting solar energy into a transmembrane proton gradient for ATP synthesis1-3. Electron transfer within cytb6 f occurs via the quinol (Q) cycle, which catalyses the oxidation of plastoquinol (PQH2) and the reduction of both plastocyanin (PC) and plastoquinone (PQ) at two separate sites via electron bifurcation2. In higher plants, cytb6 f also acts as a redox-sensing hub, pivotal to the regulation of light harvesting and cyclic electron transfer that protect against metabolic and environmental stresses3. Here we present a 3.6 Å resolution cryo-electron microscopy (cryo-EM) structure of the dimeric cytb6 f complex from spinach, which reveals the structural basis for operation of the Q cycle and its redox-sensing function. The complex contains up to three natively bound PQ molecules. The first, PQ1, is located in one cytb6 f monomer near the PQ oxidation site (Qp) adjacent to haem bp and chlorophyll a. Two conformations of the chlorophyll a phytyl tail were resolved, one that prevents access to the Qp site and another that permits it, supporting a gating function for the chlorophyll a involved in redox sensing. PQ2 straddles the intermonomer cavity, partially obstructing the PQ reduction site (Qn) on the PQ1 side and committing the electron transfer network to turnover at the occupied Qn site in the neighbouring monomer. A conformational switch involving the haem cn propionate promotes two-electron, two-proton reduction at the Qn site and avoids formation of the reactive intermediate semiquinone. The location of a tentatively assigned third PQ molecule is consistent with a transition between the Qp and Qn sites in opposite monomers during the Q cycle. The spinach cytb6 f structure therefore provides new insights into how the complex fulfils its catalytic and regulatory roles in photosynthesis