In situ Raman characterization of minerals and degradation processes in a variety of cultural and geological heritage sites

Wetest the capabilities of in situ Raman spectroscopy for non-destructive analysis of degradation processes in invaluable masterpieces, as well as for the characterization of minerals and prehistoric rock-art in caves. To this end, we have studied the mechanism of decay suffered by the 15th-century limestone sculptures that decorate the retro-choir of Burgos Cathedral (N Spain). In situ Raman probe detected hydrated sulfate and nitrateminerals on the sculptures, which are responsible for the decay of the original limestone. In addition, in situ Raman analyses were performed on unique speleothems in El Soplao Cave (Cantabria, N Spain) and in the Gruta de las Maravillas (Aracena, SWSpain). Unusual cavemineralswere detected in El Soplao Cave, such as hydromagnesite (Mg5(CO3)4(OH)2·4H2O), as well as ferromanganese oxides in the black biogenic speleothems recently discovered in this cavern. In the Gruta de las Maravillas, gypsum (CaSO4·2H2O) was identified for the first time, as part of the oldest cave materials, so providing additional evidence of hypogenic mechanisms that occurred in this cave during earlier stages of its formation. Finally, we present preliminary analyses of several cave paintings in the renowned “Polychrome Hall” of Altamira Cave (Cantabria, N. Spain). Hematite (Fe2O3) is the most abundant mineral phase, which provides the characteristic ochre-reddish color to the Altamira bison and deer paintings. Thus, portable Raman spectroscopy is demonstrated to be an analytical technique compatible with preserving our cultural and natural heritage, since the analysis does not require physical contact between the Raman head and the analyzed items

Surface and capillary transitions in an associating binary mixture model

We investigate the phase diagram of a two-component associating fluid mixture in the presence of selectively adsorbing substrates. The mixture is characterized by a bulk phase diagram which displays peculiar features such as closed loops of immiscibility. The presence of the substrates may interfere the physical mechanism involved in the appearance of these phase diagrams, leading to an enhanced tendency to phase separate below the lower critical solution point. Three different cases are considered: a planar solid surface in contact with a bulk fluid, while the other two represent two models of porous systems, namely a slit and an array on infinitely long parallel cylinders. We confirm that surface transitions, as well as capillary transitions for a large area/volume ratio, are stabilized in the one-phase region. Applicability of our results to experiments reported in the literature is discussed.Comment: 12 two-column pages, 12 figures, accepted for publication in Physical Review E; corrected versio

Caracterización multianalítica de meteorito marciano NWA2975 mediante CF-LIBS, fluorescencia de rayos X y espectroscopía Raman

La caracterización isotópica y elemental de los meteoritos de Marte ha permitido determinar la cronología de los procesos de formación del planeta y avanzar en la comprensión de su evolución biogeoquímica e hidrológica. Los meteoritos más abundantes son las rocas de origen ígneo, como las shergottitas. Los estudios petrológicos y geoquímicos previos del meteorito Northwest Africa 2975 (NWA 2975), revelaron que se trata de una roca volcánica de grano medio, entre subofítica y granular, compuesta predominantemente por piroxenos (57,3 vol.%) y plagioclasa (38,3 vol. %) completamente enmascarados con fases opacas (2,7 vol.%) y fosfatos (1,7 vol.%) [1]. El instrumento SuperCam a bordo del rover Perseverance (misión MARS 2020 de la NASA) está equipado con técnicas atómicas y moleculares (incluyendo LIBS y Raman) para la detección y análisis a distancia de muestras geológicas en la superficie del Planeta Rojo. La capacidad de estas técnicas se ha demostrado ampliamente en la caracterización de rocas, minerales y suelos en varias misiones espaciales. En el presente trabajo, se analizó un fragmento del meteorito NWA 2975 mediante un sistema de micro-LIBS con el objetivo de revelar su composición química elemental. Debido a la heterogeneidad intrínseca de la muestra, se analizaron diferentes posiciones de su superficie. El análisis cuantitativo de los elementos principales (Si, Al, Fe, Mg, Mn, Ca y O) y de otros elementos menores se llevó a cabo utilizando la metodología Calibration-Free [2]. Los resultados sugieren la presencia de piroxenos como principal componente mineral en las posiciones inspeccionadas, aunque también se pueden encontrar otras fases minerales como la plagioclasa. La información extraída del análisis LIBS se ha comparado con la de fluorescencia de rayos X (XRF) y la espectroscopia Raman. El uso combinado de diferentes técnicas espectroscópicas ha permitido obtener una mejor interpretación de los resultados composicionales.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Évolution des modes de vibration υ(OH/OD) en fonction de la température dans les monocristaux de Sr(HCOO)

Nous avons réalisé des spectres Raman dans le domaine des températures comprises entre 293K et 10K sur des monocristaux de Sr(HCOO)2.2H2O et ses analogues obtenus par substitution isotopique partielle dans l’eau d’hydratation à 80 % H2O, 56 % H2O, 31 % H2O, et 2 % H2O respectivement. En étudiant les modes internes υ(ΟΗ) et υ(OD), une transition ordre- désordre a été observée à basse température (T < 170K). Cette transition est liée à un changement de l’orientation des liaisons d’hydrogène

In situ Raman characterization of minerals and degradation processes in a variety of cultural and geological heritage sites

We test the capabilities of in situ Raman spectroscopy for non-destructive analysis of degradation processes in invaluable masterpieces, as well as for the characterization of minerals and prehistoric rock-art in caves. To this end, we have studied the mechanism of decay suffered by the 15th-century limestone sculptures that decorate the retro-choir of Burgos Cathedral (N Spain). In situ Raman probe detected hydrated sulfate and nitrate minerals on the sculptures, which are responsible for the decay of the original limestone. In addition, in situ Raman analyses were performed on unique speleothems in El Soplao Cave (Cantabria, N Spain) and in the Gruta de las Maravillas (Aracena, SW Spain). Unusual cave minerals were detected in El Soplao Cave, such as hydromagnesite (Mg5(CO3)4(OH)2·4H2O), as well as ferromanganese oxides in the black biogenic speleothems recently discovered in this cavern. In the Gruta de las Maravillas, gypsum (CaSO4·2H2O) was identified for the first time, as part of the oldest cave materials, so providing additional evidence of hypogenic mechanisms that occurred in this cave during earlier stages of its formation. Finally, we present preliminary analyses of several cave paintings in the renowned “Polychrome Hall” of Altamira Cave (Cantabria, N. Spain). Hematite (Fe2O3) is the most abundant mineral phase, which provides the characteristic ochre-reddish color to the Altamira bison and deer paintings. Thus, portable Raman spectroscopy is demonstrated to be an analytical technique compatible with preserving our cultural and natural heritage, since the analysis does not require physical contact between the Raman head and the analyzed items

MitochondriaL dysfunction:a basic mechanism in inflammation-related non-communicable diseases and therapeutic opportunities.

10.1155/2013/13569

Corrosion behavior of Zn-TiO2 and Zn-ZnO Electrodeposited coatings in 3.5% NaCl solution

Electrodeposition is a widely used method to protect metallic materials from corrosion. Electrodeposited coatings provide the metal substrate with both cathodic protection and a barrier effect. The corrosion resistance achieved with this type of zinc-electroplating process in increased by adding nanometric materials to the electrolytic bath. In the present research, coatings were obtained by electrodeposition of pure zinc, Zn-TiO and Zn-ZnO nanoparticles. The coatings were generated by immersion in a chloride acid bath applying a current density of 0.05 and 0.10 A/cm for 1 min and adding 2 g/l of TiO or ZnO nanoparticles. Corrosion behaviour was evaluated with potentiodynamic polarization curves and the electrochemical impedance spectroscopy (EIS) technique using a 3.5% NaCl test solution. After electrochemical testing, the coating surface morphology was analysed by scanning electron microscopy (SEM) and the atomic composition by energy dispersive X-ray spectroscopy (EDS). The electrodeposited coating thickness was measured using the ultrasound technique. The coating thickness was less than 2.5 μm and its corrosion resistance increased with the addition of nanoparticles.The authors would like to acknowledge the work group UANL-CA-316, and P.O. Samaniego G. D.M. Bastidas gratefully acknowledges funding from The University of Akron. Paper in memoriam of Dr. Alberto Martinez-Villafañe (†).Peer Reviewe

Novas ocorrências de Rapateaceae para o Brasil New records of Rapateaceae from Brazil

Este trabalho apresenta cinco novas ocorrências de Rapateaceae para a flora brasileira, provenientes do Monte Caburaí, Roraima, um tepui de baixa altitude no extremo norte do Brasil. Foram registrados uma espécie de Rapatea Aubl., três de Stegolepis Klotzsch ex Körn, além de uma espécie de Epidryos Maguire, sendo este o primeiro registro do gênero para a flora brasileira. São apresentadas breves descrições, ilustrações, informações sobre a distribuição geográfica e habitat das espécies, bem como comentários sobre suas afinidades taxonômicas.<br>This paper presents five new additions of Rapateaceae to the Brazilian flora from Monte Caburaí, a low-altitude tepui in Roraima state. One species of Epidryos Maguire, another of Rapatea Aubl., and three species of Stegolepis Klotzsch ex Körn were recorded. Epidryos is cited for the first time for the Brazilian flora. Brief descriptions, illustrations, geographic distribution and habitat data as well as comments on taxonomic affinities of the species are presented