137 research outputs found
Replacement of lead stabilizer in electroless nickel-boron baths : synthesis and characterization of coatings from bismuth stabilized bath
Reflexiones acerca de la exhumación de cuerpos en las altas montañas del Kollasuyo
La exhumación de cuerpos naturalmente momificados en sitios arqueológicos de altura de la cordillera de los Andes se vienen produciendo desde hace un siglo, pero recién en los últimos años, éstos, dejaron de ser hallazgos casuales de arrieros o montañistas, para convertirse en hallazgos causales producidos por profesionales, a través de excavaciones sistemáticas y fuertes financiaciones. En este sentido la década de 1990 marca un hito tan importante para la ciencia como peligroso para la protección del patrimonio cultural. En el presente trabajo se brinda un panorama histórico de dichas exhumaciones y sus implicancias sociales en el más amplio sentido del término; se analiza la necesidad de una discusión tanto teórica-metodológica como ética y se proponen algunas alternativas para el casoAsociación de Antropología Biológica de la República Argentin
Reflexiones acerca de la exhumación de cuerpos en las altas montañas del Kollasuyo
La exhumación de cuerpos naturalmente momificados en sitios arqueológicos de altura de la cordillera de los Andes se vienen produciendo desde hace un siglo, pero recién en los últimos años, éstos, dejaron de ser hallazgos casuales de arrieros o montañistas, para convertirse en hallazgos causales producidos por profesionales, a través de excavaciones sistemáticas y fuertes financiaciones. En este sentido la década de 1990 marca un hito tan importante para la ciencia como peligroso para la protección del patrimonio cultural. En el presente trabajo se brinda un panorama histórico de dichas exhumaciones y sus implicancias sociales en el más amplio sentido del término; se analiza la necesidad de una discusión tanto teórica-metodológica como ética y se proponen algunas alternativas para el casoAsociación de Antropología Biológica de la República Argentin
HOW HEAT TREATMENT CAN GIVE BETTER PROPERTIES TO ELECTROLESS NICKEL-BORON COATINGS
Electroless nickel-boron deposits were synthesized on mild steel and submitted to heat treatments under neutraland nitrogen based atmosphere. The properties obtained after these treatments were compared to as depositednickel-boron coatings. The morphology and structure of the samples were investigated by XRD, SEMand optical microscopy; their composition was studied by ICP, GD-OES and SIMS analysis, and micro andnanoindentation tests were carried out to assess the coatings’ hardness. Scratch tests were used to determinethe damage mechanisms of the coating
High-resolution characterization of the diffusion of light chemical elements in metallic components by scanning microwave microscopy
International audienceAn original sub-surface, high spatial resolution tomographic technique based on scanning microwave microscopy (SMM) is used to visualize in-depth materials with different chemical compositions. A significant phase difference in SMM between aluminum and chromium buried patterns has been observed. Moreover this technique was used to characterize a solid solution of a light chemical element (oxygen) in a metal lattice (zirconium). The large solubility of the oxygen in zirconium leads to modifications of the properties of the solid solution that can be measured by the phase shift signal in the SMM technique. The signal obtained in cross-section of an oxidized Zr sample shows the excellent agreement between phase shift profiles measured at different depths. Such a profile can reveal the length of diffusion of the oxygen in zirconium under the surface. The comparison with the oxygen concentration measured by nuclear reaction analysis shows excellent agreement in terms of length of diffusion and spatial distribution of the oxygen. A rapid calibration shows a linear dependence between the phase shift and the oxygen concentration. The SMM method opens up new possibilities for indirect measurements of the oxygen concentration dissolved in the metal lattic
Formation of Flavanol-aldehyde Adducts in Barrel-aged White Wine – Possible Contribution of These Products to Colour
This paper describes the formation and diversity of new compounds resulting from the polymerisation of furanic andphenolic flavanol-aldehydes with HPLC‑DAD and LC‑ES/MS analysis. Polymerisation, resulting from nucleophilicreactions, formed dimers, trimers, soluble and insoluble polymers. Reactions in hydroalcoholic solution with purealdehydes (phenolic and furanic) and flavanols (catechin) were studied. The study was repeated with differentaldehydes in white wine. This research focused particularly on the colour properties of the released products and theirpotential impact on the colour of white wine. Some products were purified and isolated; these were mainly catechinfurfuraldehyde,catechin-methyl-5-furfuraldehyde, catechin-hydroxymethyl-furfuraldehyde,catechin-vanillin, andcatechin-syringaldehyde dimers. The most powerful coloured products resulted from furanic aldehydes. Over thecourse of the experiment, the reaction produced dimers, trimers and oligomers. After 50 to 60 days, the colour of thesolution was mainly due to soluble polymeric forms. In addition, the role of SO2, generally used during vinificationand ageing, was studied. The influence of SO2 on the kinetics of the reaction was limited
Muscle atrophy phenotype gene expression during spaceflight is linked to a metabolic crosstalk in both the liver and the muscle in mice
Human expansion in space is hampered by the physiological risks of spaceflight. The muscle and the liver are among the most affected tissues during spaceflight and their relationships in response to space exposure have never been studied. We compared the transcriptome response of liver and quadriceps from mice on NASA RR1 mission, after 37 days of exposure to spaceflight using GSEA, ORA, and sparse partial least square-differential analysis. We found that lipid metabolism is the most affected biological process between the two organs. A specific gene cluster expression pattern in the liver strongly correlated with glucose sparing and an energy-saving response affecting high energy demand process gene expression such as DNA repair, autophagy, and translation in the muscle. Our results show that impaired lipid metabolism gene expression in the liver and muscle atrophy gene expression are two paired events during spaceflight, for which dietary changes represent a possible countermeasure
Spatiotemporal trends in cetacean strandings and response in the southwestern Indian Ocean : 2000–2020
On behalf of SIF, we would like to thank the Seychelles partners (Alphonse Foundation, Desroches Foundation, Island Conservation Society, Farquhar Foundation, Seychelles Islands Foundation, Silhouette Foundation) for providing financial support to acquire and grant use of their data. Collection of data in Reunion was funded by DEAL Reunion and Region-Reunion.The south-western Indian Ocean (SWIO) is a region of global importance for marine mammal biodiversity, but our understanding of most of the species and populations found there is still rudimentary. The Indian Ocean Network for Cetacean Research (IndoCet) was formed in 2014 and is dedicated to the research of all cetacean species across the SWIO. Since 2019, there have been efforts to create a regional network for coordinated response to stranding events as well as training and capacity building in the SWIO region. The present analysis represents a first investigation of stranding data collected by various members and collaborators within the IndoCet network, covering over 14,800km of coastline belonging to nine countries/territories. Between 2000–2020, there were 397 stranding events, representing 1,232 individual animals, 17 genera and 27 species, belonging to six families: four balaenopterids, one balaenid, one physeterid, two kogiids, six ziphiids and 14 delphinids. Seven mass strandings were recorded: two were composed of three to 20 individuals and five composed of > 20 individuals. Spatial analysis of stranding events indicated that local spatio-temporal clusters (excessive number of events in time and geographic space) were present in all countries/territories, except for the Comoros. The only significant cluster was detected on the southwest coast of Mauritius, just west of the village of Souillac. The SWIO region predominantly comprises relatively poor countries/territories, but imminent Ocean Economy developments are prevalent throughout the region. This study highlights the importance of establishing baselines upon which any future potential impact from anthropogenic developments in the region can be measured.Peer reviewe
Mechanically assisted electrochemical degradation of alumina-TiC composites
Alumina-TiC composite material is a tough ceramic composite with excellent hardness, wear resistance and oxidation resistance in dry and high-temperature conditions. In aqueous conditions, however, it is likely to be electrochemically active facilitating charge transfer processes due to the conductive nature of TiC. For application as an orthopedic biomaterial, it is crucial to assess the electrochemical behavior of this composite, especially under a combined mechanical and electrochemical environment. In this study, we examined the mechanically assisted electrochemical performance of alumina-TiC composite in an aqueous environment. The spontaneous electrochemical response to brushing abrasion was measured. Changes in the magnitude of electrochemical current with abrasion test conditions and possible causal relationship to the alteration in surface morphology were examined. Results showed that the alumina matrix underwent abrasive wear with evidence of microploughing and grain boundary damage. Chemical analysis revealed TiO2 formation in the abraded region, indicating oxidation of the conductive TiC domain. Furthermore, wear debris from alumina abrasion appeared to affect reaction kinetics at the composite-electrolyte interface. From this work, we established that the composite undergoes abrasion assisted electrochemical degradation even in gentle abrasive conditions and the severity of degradation is related to temperature and conditions of test environment
Resolving anaphoras for the extraction of drug-drug interactions in pharmacological documents
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