Effect of cathode contacting on anode supported cell performances and degradation

The contact geometry effect on anode-supported cells (ASC) has been evaluated comparing the use of platinum meshes and Crofer 22 APU bipolar plates as current collectors. Additionally, the application of a La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) paste between the electrode and the current collector allowed estimating the beneficial effect of the contacting layer enhancing the current distribution at the cathode side. Cells have been electrically loaded for 100 hours to investigate the polarization effects on their performances by means of current-voltage curves and electrochemical impedance spectroscopy. Post-experiment analyses have been carried out to support the electrochemical observation

Interaction between crofer 22 APU current collector and LSCF cathode contacting layer under cell operation

In this work the oxidation of Crofer 22 APU and its interaction with La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) applied as contacting layer have been investigated in air at 750\ub0C under a current load of 0.5 Acm-2 with the aim to reproduce as close as possible the interconnect interface in real operating conditions. The effects of such interaction and of the pre-oxidation treatment have been studied by means of ASR measurement and post-experiment characterizations. The behavior of such samples has been compared with the results on a working Crofer 22 APU bipolar plate tested as cathode current collector of an anode-supported cell reproducing the stack cathode compartment conditions

An analytical model for the mechanical deformation of locally graphitized diamond

We propose an analytical model to describe the mechanical deformation of single-crystal diamond following the local sub-superficial graphitization obtained by laser beams or MeV ion microbeam implantation. In this case, a local mass-density variation is generated at specific depths within the irradiated micrometric regions, which in turn leads to swelling effects and the development of corresponding mechanical stresses. Our model describes the constrained expansion of the locally damaged material and correctly predicts the surface deformation, as verified by comparing analytical results with experimental profilometry data and Finite Element simulations. The model can be adopted to easily evaluate the stress and strain fields in locally graphitized diamond in the design of microfabrication processes involving the use of focused ion/laser beams, for example to predict the potential formation of cracks, or to evaluate the influence of stress on the properties of opto mechanical devices.Comment: 29 pages, 7 figure

Metales del Noroeste argentino en las colecciones arqueológicas del Field Museum de Chicago

Damos a conocer el conjunto de piezas metálicas arqueológicas de la colección Zavaleta, actualmente resguardada en el Field Museum of Natural History de Chicago (Illinois, Estados Unidos). La historia de formación de la colección será brevemente revisada (Gluzman 2017) para luego presentar las características morfológicas, funcionales y tecnológicas de este universo específico de objetos. Manuel Zavaleta, su colector, expuso e instaló bajo el apoyo del estado argentino un lote de 4565 objetos en la Louisiana Purchase Exposition (Saint Louis, Missouri) (1904), que al final de la exposición fue adquirido por el museo de Chicago. Más de 180 piezas de metal, procedentes del Noroeste argentino (provincias de Salta, Tucumán y Catamarca) hacen de esta colección la más importante en su tipo fuera de Argentina. Guiándonos por los archivos correspondientes a la colección Zavaleta, al menos 293 objetos de metal formaban la colección originalmente. Intercambios con otras instituciones, principalmente de los Estados Unidos como el Museum of American Indian, explican la diferencia con el número actual.Fil: Gluzman, Geraldine Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto de las Culturas. Universidad de Buenos Aires. Instituto de las Culturas; Argentina. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Museo Etnográfico "Juan B. Ambrosetti"; ArgentinaFil: Piccardo, Paolo. Università degli Studi di Genova; ItaliaVII Congreso Nacional de ArqueometríaAmaicha del ValleArgentinaUnviersidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Centro de Investigaciones en Ecología Históric

Aging of materials at inlet and outlet fuel manifolds in a SOFC stack

Analyses performed on a stack operated for more than 4000h at 750\ub0C at high fuel utilization (80%) revealed significant differences in aging behaviour of stack components when comparing fuel inlet and fuel outlet areas. Two samples were cut from the fuel inlet and outlet manifolds of the operated SOFC stack. The glass-ceramic sealing material and the interconnect alloy were exposed to a dual atmosphere (external air and internal fuel stream). The fuel composition was dry H2/N2 (60:40 vol. %) at the inlet and H2O/H2/N2 (48:12:40 vol. %) at the outlet. The stack was operated in co-flow configuration, with a large excess of air. It was found that the interfaces between the seal and the alloy were significantly affected by the difference in fuel composition. The sealant exposed to the outgoing air was significantly polluted by chromium generated in the stack and transported by the air stream. These investigations therefore reveal that the long-term evolution of the sealing and of the metallic support depends on the local conditions in the stack, as well as on additional interactions with other degradation phenomena

A morphological and chemical classification of bronze corrosion features from an Iron Age hoard (Tintignac, France): the effect of metallurgical factors

A categorization of corrosion morphologies of archaeological Sn bronzes was carried out on archaeological Iron Age objects. The objects come from a Celtic deposit located in central France (Tintignac, Corrèze) and are dated between 2nd and 3rd cent BC. Being samples of corroded metals taken from a single find spot, parameters connected to the features of the alloy and known to influence the corrosion morphologies were thoroughly considered. Global processes were highlighted, and corrosion mechanisms were characterized with a multi-analytical protocol (SEM-EDS, micro-Raman spectroscopy, image analyses) according to the detected morphology. Elaboration of the results was carried out with a multicomponent approach. Results show the presence of 5 different morphologies correlated to the alloys characteristics of the objects. Alloy composition, microstructure, degree of deformation and grain size were found to influence the corrosion products formed and the morphology of the attack. In particular, the 'tentacle like corrosion', associated to a microbial attack was the most susceptible to the effect of metallurgical features: their occurrence is connected to a higher presence of Fe and Pb in the alloy, a homogeneous deformation and a larger grain size

Un bras d’empereur romain en bronze à Essegney (Vosges)

Le bras gauche d’une statue de bronze d’époque romaine, découvert fortuitement en Lorraine (Essegney, Vosges), provient d’une statue d’empereur, que les parallèles les plus proches inviteraient à dater de l’époque sévérienne. On ne voit guère de quel site voisin il pourrait provenir. Le bon état du bras et l’accessibilité de l’intérieur ont permis une étude poussée des procédés de fabrication.The bronze left arm dating from the gallo-roman period, discovered accidentally in the Lorraine region (Essegney, Vosges), belongs to the statue of an emperor, the nearest parallels of which date to the Severian period. The neighbouring site from which the find could have originated has not of yet been identified. The fabrication processes have undergone detailed study due to the good preservation and the hollow nature of the piece.Der zufällig in Lothringen (Essegney, Vogesen) entdeckte linke Arm einer Bronzestatue aus römischer Zeit gehört zu einer Kaiserstatue, deren nächste Parallelen eine Datierung in die severische Zeit nahe legen. Es ist schwer vorstellbar, von welchem nahen Fundplatz der Arm stammen könnte. Der gute Zustand des Armes und die Möglichkeit, sein Inneres zu untersuchen, haben eine eingehende Untersuchung der Herstellungstechniken erlaubt

Patient Age Is an Independent Risk Factor of Relapse of Differentiated Thyroid Carcinoma and Improves the Performance of the American Thyroid Association Stratification System

Background: The 2015 American Thyroid Association (ATA) guidelines proposed a three-category system for estimating the risk of recurrence of differentiated thyroid carcinoma (DTC). This system includes several perioperative features, but not age at diagnosis. However, age has traditionally been recognized as a critical factor in the survival of DTC patients, and the eighth edition of TNM stated that patients older than 55 years were at higher risk of death. In this study, we raised the question of whether age at DTC diagnosis impacts on its risk of recurrence. Specifically, the present study aimed to (i) evaluate the association between age at diagnosis and structural recurrence and (ii) investigate whether age at diagnosis could improve the performance of the ATA system. Methods: During the study period, four institutions selected DTC patients treated with both thyroidectomy and radioiodine and who had follow-up for at least one year. Patients with proven structural evidence of disease during follow-up were identified, and disease-free survival (DFS) was calculated accordingly. Results: The study involved 1603 DTC patients with a median age of 49 years and DFS of 44 months. Disease recurred in 8%. The shortest DFS was found in the oldest patients. The Kaplan-Meier curves were calculated for each decade of age, and there was a significant association with DFS (p = 0.0014). Patients older than 55 years had significantly higher risk (hazard ratio [HR] 1.78, 95% confidence interval [CI 1.23-2.56]). The Kaplan-Meier curves of DFS in high-, intermediate-and low-risk groups showed a significant association only in the high-risk group (p = 0.0058). Patients older than 55 years had significantly higher risk of relapse over time only in the high-risk group (HR 2.15 [CI 2.01-4.53]). Cox's proportional analysis showed that the age cutoff of 55 years and the ATA system were significant predictors of relapse. Adding age at diagnosis above 55 years to the ATA system identified a subgroup of patients at highest risk for relapse. Conclusions: The age threshold adopted in the eighth edition of TNM staging system for DTC patients' prognosis also identifies cases at higher risk of relapse. Applying age at diagnosis, with a cutoff of 55 years, to the ATA risk stratification system identifies cases at highest risk of relapse

Lethal and Sublethal Responses of Hydropsyche pellucidula (Insecta, Trichoptera) to Commercial Polypropylene Microplastics after Different Preconditioning Treatments

Microplastics (MPs) pose biological and chemical hazards in aquatic and terrestrial food webs across the globe. Research on microplastic contamination has long focused on marine ecosystems, whereas the toxicological impact on freshwater organisms is still little explored. In this study, the lethal and sublethal response of the freshwater macroinvertebrate Hydropsyche pellucidula exposed to polypropylene MPs after different pre-conditioning treatments was assessed. Field samples were collected in a riverine system (Vipacco river; northeast Italy) to assess the characteristics of the MPs in the aquatic environment Both water and sediment were contaminated by MPs (3.73 ± 2.11 items m−3 per min and 3.33 ± 4.16 items dm−3, respectively). The chemical MPs composition included polystyrene, polyethylene terephthalate, polyurethane, polyamide, polypropylene, and polyethylene. Polypropylene (PP), although not the most abundant polymer recorded in the study area, was preferred over the other types according to its abundance in freshwater and H. pellucidula feeding behavior. A housing test was performed to recreate the natural conditions of larvae sampled for a reliable response to the ecotoxicological tests. The microplastics underwent either preconditioning with Vipacco River water (PP-river) and surfactant Triton X-100 (PP-sf) or no pre-treatment (PP). Submersion of microplastics in 10 µg L−1 of surfactant solution for 24 h was sufficient to induce consistent spectral changes and modify the chemical profile of the plastic surface. Mortality rate differed according to treatment: PP and PP-river > positive control > PP-sf > negative control. Integrated biomarker response (IBRv2) and analysis of oxidative stress biomarker levels showed a greater response of superoxide dismutase and lipid peroxidation (malondialdehyde) in larvae treated with PP conditioned in surfactant. Our findings enhance knowledge on the toxicity of PP and conditioning phases on H. pellucidula larvae.This research received no external funding.Peer reviewe