Elaboration of metallic compacts with high porosity for mechanical supports of SOFC

The development of third generation Solid Oxide Fuel Cells (SOFC) with metallic mechanical supports presents several advantages over that of ceramic stacks by offering a lower cost and longer lifetime of the stacks. As a consequence, it is necessary to prepare metallic porous compacts that remain stable at the operating temperature of the SOFC (700–800 C) under reductive atmosphere. This paper presents an innovative process to elaborate iron, nickel and cobalt porous compacts. The process is based on the thermal decomposition of metal oxalate precursors with controlled morphology into metallic powders with coralline shape. Uniaxial compaction of such powders (without binder addition to the powders) under low uniaxial pressures (rising from 20 to 100 MPa) gave rise to green compacts with high porosity and good mechanical properties. After annealing at 800 C under H2 atmosphere, the compacts still present interconnected porosity high enough to allow sufficient gas flow to feed a SOFC single cell in hydrogen: the porosity rises from 25 to 50% for iron compacts, from 20 to 50% for cobalt compacts, and is higher than 40% for nickel compacts. Results from physicochemical characterization (XRD, SEM, gas permeation, Hg porosimetry) corroborated the process for SOFC application

Crystal structure of the A domain from the a subunit of integrin CR3 (CD11 b/CD18)

AbstractWe have determined the high resolution crystal structure of the A domain from the a chain of integrin CR3. The domain adopts a classic α/β “Rossmann” fold and contains an unusual Mg2+ coordination site at its surface. One of the coordinating ligands is the glutamate side chain from another A domain molecule. We suggest that this site represents a general metal ion-dependent adhesion site (MIDAS) for binding protein ligands. We further propose that the subunits of integrins contain a MIDAS motif within a modified A domain. Our crystal structure will allow reliable models to be built for other members of the A domain superfamily and should facilitate development of novel adhesion modulatory drugs

Impact of prosthesis-patient mismatch in the mitral position on left atrial and pulmonary arterial pressures: a numerical study

Prosthesis-patient mismatch (PPM) occurs when the effective orifice area (EOA) of the prosthesis is too small in relation to the body size and thus to the cardiac output requirement of the patient. A recent retrospective study from our group suggests that mitral PPM defined as an indexed EOA < 1.2 cm2/m2 is associated with lesser regression of pulmonary hypertension after mitral valve replacemen

Development of a sensitive and selective mixed-potential ammonia sensor for automotive exhausts

Session: A5 Oxide Based Sensors and ActuatorsInternational audienceOne of the most effective technologies in decreasing large-scale NOx emission produced by diesel engine vehicles is Urea-SCR (selective catalytic reduction) system. In order to prevent inducing excessive ammonia to the environment, an NH3 sensor is required at the exit of this system. In this study, highly selective ammonia sensors were developed to detect ammonia emissions from automotive exhaust.The sensors were fabricated with 8-YSZ electrolyte, a platinum reference electrode and a working electrode of Au-V2O5 (mass ratio: 85:15), screen-printed on an alumina supports. A platinum resistor was printed at the backside of the support to control the sensor temperature. The measured sensor response (ΔV) is the potential difference between reference and working electrodes. Figure 1 shows the responses of two identical sensors to 100 ppm CO, NO2, NO and 20 ppm of NH3 at four different temperatures. It can be seen that the sensors respond to all gases at lower temperatures while by increasing temperature to 600 °C the selectivity to NH3 is greatly improved. The selectivity of sensors was also confirmed by testing other possible interfering gases and no responses were observed for 20ppm of H2 and 100ppm of a hydrocarbon mixture. The stability of such sensors was studied at 550 °C and 600 °C. Since sensors showed no long term stability at 600 °C (electrode degradation), but remain stable results at 550 °C, investigations were made to decrease the selective working temperature while maintaining selectivity. After testing different mass percentages of V2O5 in working electrode, we observed that by increasing this value to 50%, the working temperature of selective ammonia sensors could be decreased to 550 °C with stable responses. Further investigations will be performed in order to gain deeper insight in sensing mechanism of V2O5 based working electrodes, which governs the sensor’s performance

Icodextrin-induced peritonitis: Study of five cases and comparison with bacterial peritonitis

Icodextrin-induced peritonitis: Study of five cases and comparison with bacterial peritonitis.BackgroundAn epidemic of aseptic peritonitis related to the presence of peptidoglycan contaminant in some batches of icodextrin solution (Extraneal®, Baxter Healthcare Corporation) occurred in Europe in the first six months of 2002.MethodsBy case-control study we examined the clinical and biologic features of 5 patients with icodextrin-induced peritonitis (group AP) and compared them with 7 patients with bacterial peritonitis (group BP) recruited in our clinical center between January and June 2002.ResultsDiagnosis of icodextrin-induced peritonitis was confirmed in all cases by a positive reintroduction test with contaminated batches of icodextrin. No recurrence was observed on re-exposure to icodextrin free of peptidoglycan. Skin tests were positive with contaminated icodextrin in 2 of 5 patients, while they were negative with icodextrin solution free of peptidoglycan (<0.6ng/mL). During peritonitis, serum level of C-reactive protein (CRP) was lower in group AP (42.4 ± 34mg/L) than in group BP (135 ± 59mg/L) (P = 0.01). Leukocyte number in peritoneal dialysis effluent was lower in group AP (284 ± 101/mm3), with a lower neutrophil/monocyte ratio (N/M = 0.67) than in group BP (1410 ± 973/mm3; N/M = 4) (P < 0.05). A low number of peritoneal fluid eosinophilia (11 ± 8%) was detected in group AP.ConclusionIcodextrin-induced peritonitis was associated with a burst of intraperitoneal cytokines. The phenotype of peritoneal neutrophils was different between aseptic and bacterial peritonitis, indicating that inflammatory stimuli that activate neutrophils in both types of peritonitis are clearly distinct. Finally, peritoneal injury measured by weight gain, peritoneal permeability, and CA125 concentration seemed to be less severe during icodextrin-induced peritonitis than during bacterial peritonitis

Emergence des nanotechnologies : Vers un nouveau "modèle industriel "?

Les technologies émergentes comme la microélectronique des années 70, les biotechnologies des années 80-90 ou les nanotechnologies des années 2000 s'expriment sous forme de vagues technologiques (Kahane, 2008) qui sont porteuses de promesses scientifiques et techniques (Pautrat, 2002), de nouveaux marchés, de perspectives de bien-être pour certains (Birraux et al., 2003), de risques, d'incertitudes et d'aliénation pour d'autres (Dupuy et al., 2004). Alors que le développement économique des nanotechnologies ne fait que commencer, plusieurs schémas de développement sont envisageables (Kahane, Mangematin, 2007).Pour plus d'informations consulter le site http://www.nanoeconomics.eu/

La tecno-ciencia en cuestión. Elementos para una arqueología del siglo XX

Estos fragmentos corresponden al libro que tiene el mismo el nombre, publicado en Seyssel por la editorial Champ Vallon en 1990.Traducción del francés al español de Luis Alfonso Palau, Medellín, febrero d 2015-abril de 2017. Nota del editor. IntroducciónTécnicas avanzadas, tecnologías de punta, desafío técnico, transferencia de tecnología, riesgos tecnológicos importantes, tecnoestructuras, biotecnologías… La técnica o el envite del siglo1… Discursos y escritos nos devuelven el eco de los efectos inducidos por el desarrollo de los instrumentales a través de los cuales nuestras sociedades dominan y utilizan energía e información

A multi-targeted approach to suppress tumor-promoting inflammation

Cancers harbor significant genetic heterogeneity and patterns of relapse following many therapies are due to evolved resistance to treatment. While efforts have been made to combine targeted therapies, significant levels of toxicity have stymied efforts to effectively treat cancer with multi-drug combinations using currently approved therapeutics. We discuss the relationship between tumor-promoting inflammation and cancer as part of a larger effort to develop a broad-spectrum therapeutic approach aimed at a wide range of targets to address this heterogeneity. Specifically, macrophage migration inhibitory factor, cyclooxygenase-2, transcription factor nuclear factor-κB, tumor necrosis factor alpha, inducible nitric oxide synthase, protein kinase B, and CXC chemokines are reviewed as important antiinflammatory targets while curcumin, resveratrol, epigallocatechin gallate, genistein, lycopene, and anthocyanins are reviewed as low-cost, low toxicity means by which these targets might all be reached simultaneously. Future translational work will need to assess the resulting synergies of rationally designed antiinflammatory mixtures (employing low-toxicity constituents), and then combine this with similar approaches targeting the most important pathways across the range of cancer hallmark phenotypes