Formation of iron-carbonate scale-layer and corrosion mechanism of API X70 pipeline steel in carbon dioxide-saturated 3% sodium chloride

This work presents the electrochemical results obtained during the study of the corrosion of X70 pipeline steel samples immersed in a 3 % wt NaCl solution saturated with CO2 at 20ºC under static and controlled turbulent flow conditions. In order to control the hydrodynamic conditions of the system, a rotating cylinder electrode (RCE) was used. Electrochemical techniques, Linear Polarization Resistance (LPR) and polarization curves, were used to determine the effect of turbulent flow upon the corrosion kinetics of the steel. We also elucidate the effect of temperature on the corrosion rate of the API X70 steel under the experimental conditions studied. Often, the corrosion of carbon steel in aqueous environments containing CO2 involves the formation of solid iron carbonate, FeCO3, as a corrosion product. The protective property of the formed FeCO3 scale layer to corrosion in brine solutions containing CO2 was established as the possible cause of the corrosion rate decrease above 60ºC

Aplicaciones eléctricas del acrilonitrilo butadieno estireno (ABS) reforzado con neumáticos fuera de uso (GTR)

La masiva fabricación de neumáticos, así como su posterior almacenamiento una vez utilizados, constituye un grave problema medioambiental al que se intenta dar salida de diversas formas, entre las que se encuentra el mezclar estos neumáticos fuera de uso (old used tires, GTR) con diferentes polímeros termoplásticos y termoestables. Estas mezclas se realizan variando el tratamiento previo al que se somete el GTR, el grado de desvulcanizado, las condiciones de mezcla o prensado, etc. Posteriormente, se analizan estas mezclas estructural y mecanicamente, buscando posibles aplicaciones industriales para ellas. El presente trabajo, pretende conseguir materiales aptos para la industria eléctrica a partir de la mezcal del Acrilonitrilo butadieno estireno (ABS) reutilizado con neumáticos fuera de uso (GTR), pero partiendo del requisito de unos mínimos costes de reciclado posibles, es decir, utilizando GTR vulcanizado y sin aplicar ningún pretratamiento previo, y en cambio, actuando sobre el tamaño de sus partículas, el cual se puede conseguir con un simple y economico tamizado. Otra novedad que introduce el presente estudio, es el elevado número de compuestos analizados, aparte del profundo analisis a los que se les ha sometido (dieléctrico, mecánico, térmico y de microestructura), obteniendose de cada ensayo una gran cantidad de variables. Los compuestos se obtuvieron tomando como variables los tres tamaños de particula del GTR (p<200μm, 200<p<500μm, y p>500μm), y las siete concentraciones de GTR en la mezcla (0%, 5%, 10%, 20%, 40%, 50% y70%), lo que representa, un total de 21 nuevos compuestos. Aparte, para que los ensayos dieléctricos fueran lo más exhaustivos posibles y mostraran el comportamiento del compuesto en condiciones muy diversas, se consideró un amplio régimen de temperaturas (30ºC hasta 120ºC) así como de frecuencias (1・10  -2 Hz hasta 3・106 Hz). Todos estos datos, han permitido caracterizar con bastante exactitud las propiedades de los nuevos compuestos, y dependiendo de estos resultados, se han buscado posibles aplicaciones eléctricas, con el requisito de que estas debían ajustarse a las Normativas Oficiales

Propiedades dieléctricas y mecánicas del polietileno de alta densidad (HDPE) reforzado con neumáticos fuera de uso (GTR)

La eliminación o reciclado de los neumáticos utilizados constituye hoy en día un grave problema medioambiental, y aunque se ha avanzado en su estudio, existiendo diversos metodos para su reciclaje como la trituración mecánica, que separa el caucho vulcanizado del acero y las fibras permitiendo su utilización en diversas aplicaciones industriales, el gran volumen de neumáticos hace necesario encontrar nuevas fórmulas que permitan ayudar a la eliminación del excedente de este material de rechazo. En este artículo se propone una nueva forma para el aprovechamiento del neumático reutilizado (GTR), utilizando el polvo de este neumático como refuerzo y el polietileno de alta densidad reciclado (HDPE) como matriz, creando un nuevo compuesto, el cual para ser útil en la industria debe mantener dentro de unos valores aceptables las propiedades dieléctricas y mecánicas del polímero original. Concretamente, el polvo de los neumáticos reutilizados resultado de los procesos industriales de molienda, es separado por tamizado en tres categorías de tamaño de partículas (<200 μm, 200-500μm, y >500 μm), y mezclado con el HDPE en diversas concentraciones (0%, 5%,10%, 20%, 40%, 50% y 70% de GTR) para así determinar su comportamiento mediante los ensayos dieléctricos y mecánicos, realizados en un rango de temperaturas que varía desde los 30ºC hasta los 130ºC, y con unas frecuencias desde 1·10-2 Hz, hasta 1·107 Hz. Mediante los ensayos dieléctricos se han analizado la permitividad, la conductividad, el factor de pérdidas dieléctricas, el modulo dieléctrico etc., mientras que con los ensayos mecánicos de Tracción-Deformación, se han analizado el Modulo de Young, la tensión a la tracción, y la elongación y energía a la rotura

Características dieléctricas de diversos polímeros (PVC, EVA, HDPE, y PP) reforzados con neumáticos fuera de uso (GTR)

La masiva fabricación de neumáticos y la dificultad para su almacenamiento o eliminación constituye un grave problema medioambiental. En la actualidad, se utilizan diversos metodos para el reciclaje de los neumáticos, como por ejemplo la trituración mecánica, que separa el caucho vulcanizado del acero y las fibras, utilizandose este caucho en numerosas aplicaciones industriales como pavimentos, aislantes, calzados, etc. El presente artículo se centra en buscar una nueva aplicación para estos neumáaticos reutilizados (GTR), y para ello, se ha mezclado el polvo de los neumáticos con diferentes polímeros termoplásticos como son el Policloruro de Vinilo (PVC), el Polietileno de Alta Densidad (HDPE), el Etileno Acetato de Vinilo (EVA) y el Polipropileno (PP), comprobando hasta que valores de concentracion en GTR admitenestos nuevos compuestos manteniendo dentro de unos valores aceptables sus propiedades dielectricas, y por tanto, sus posibles aplicaciones industriales en la fabricación de aislantes para cables eléctricos. Concretamente, el polvo de los neumáticos reutilizados y con un tamaño de partícula inferior a 200 μm, ha sido mezclado con los polímeros con cuatro concentraciones diferentes, 5%, 10%, 20% y 50% en GTR para asi determinar su comportamiento mediante los ensayos dieléctricos realizados en un rango de temperaturas que varia desde los 30oC hasta los 120oC, y con unas frecuencias entre 1・10  -2 Hz, hasta 3・10  6Hz, analizandose la conductividad, la permitividad, el factor de perdidas dieléctricas, las relajaciones, etc. Finalmente, las superficies de fractura de las muestras compuestas han sido evaluadas por microscopía electronicade barrido (SEM)

Corrosion study of pipeline carbon steel in sourbrine under turbulent flow conditions at 60°C

This work presents the electrochemical results obtained during the corrosion study of X52 pipeline steel sample, immersed in “sour” solution under turbulent flow conditions at 60°C. In order to obtain information on the corrosion kinetics, weight loss method, linear polarization resistance, impedance and polarization curves were used at different immersion times. In order to control the turbulent flow conditions, a rotating cylinder electrode was used at two different rotation rates, 0 and 1000 rpm. A surface analysis was carried out in order to identify the corrosion morphology and the corrosion product formed on the steel sample. In general, it was found that flow has a considerable influence upon the electrochemical process occurring on the surface of the steel. It was observed as the flow rate increased the corrosion rate also increased. In surface analysis three phases were found, mackinawite (Fe,Ni)  1+xS ,pyrrhothite (Fe(1-x)S) and marcasite (FeS2). In addition, a “localized attack” was found

Elastography methods for the non-invasive assessment of portal hypertension

INTRODUCTION: The gold standard to assess the presence and severity of portal hypertension remains the hepatic vein pressure gradient, however the recent development of non-invasive assessment using elastography techniques offers valuable alternatives. In this review, we discuss the diagnostic accuracy and utility of such techniques in patients with portal hypertension due to cirrhosis. AREAS COVERED: A literature search focused on liver and spleen stiffness measurement with different elastographic techniques for the assessment of the presence and severity of portal hypertension and oesophageal varices in people with chronic liver disease. The combination of elastography with parameters such as platelet count and spleen size is also discussed. EXPERT COMMENTARY: Non-invasive assessment of liver fibrosis and portal hypertension is a validated tool for the diagnosis and follow-up of patients. Baveno VI recommended the combination of transient elastography and platelet count for ruling out varices needing treatment in patients with compensated advanced chronic liver disease. Assessment of aetiology specific cut-offs for ruling in and ruling out clinically significant portal hypertension is an unmet clinical need. The incorporation of spleen stiffness measurements in non-invasive algorithms using validated software and improved measuring scales might enhance the non-invasive diagnosis of portal hypertension in the next five years

CD32 is expressed on cells with transcriptionally active HIV but does not enrich for HIV DNA in resting T cells

The persistence of HIV reservoirs, including latently infected, resting CD4+ T cells, is the major obstacle to cure HIV infection. CD32a expression was recently reported to mark CD4+ T cells harboring a replication-competent HIV reservoir during antiretroviral therapy (ART) suppression. We aimed to determine whether CD32 expression marks HIV latently or transcriptionally active infected CD4+ T cells. Using peripheral blood and lymphoid tissue of ART-treated HIV+ or SIV+ subjects, we found that most of the circulating memory CD32+ CD4+ T cells expressed markers of activation, including CD69, HLA-DR, CD25, CD38, and Ki67, and bore a TH2 phenotype as defined by CXCR3, CCR4, and CCR6. CD32 expression did not selectively enrich for HIV- or SIV-infected CD4+ T cells in peripheral blood or lymphoid tissue; isolated CD32+ resting CD4+ T cells accounted for less than 3% of the total HIV DNA in CD4+ T cells. Cell-associated HIV DNA and RNA loads in CD4+ T cells positively correlated with the frequency of CD32+ CD69+ CD4+ T cells but not with CD32 expression on resting CD4+ T cells. Using RNA fluorescence in situ hybridization, CD32 coexpression with HIV RNA or p24 was detected after in vitro HIV infection (peripheral blood mononuclear cell and tissue) and in vivo within lymph node tissue from HIV-infected individuals. Together, these results indicate that CD32 is not a marker of resting CD4+ T cells or of enriched HIV DNA–positive cells after ART; rather, CD32 is predominately expressed on a subset of activated CD4+ T cells enriched for transcriptionally active HIV after long-term ART

Mobilization of xanthine oxidase from the gastrointestinal tract in acute pancreatitis

BACKGROUND: Xanthine oxidoreductase has been proposed to play a role in the development of local and systemic effects of acute pancreatitis. Under physiologic conditions, the enzyme exists mainly as xanthine dehydrogenase (XDH) but can be converted by proteolytic cleavage to its superoxide-generating form xanthine oxidase (XOD). In addition to its intracellular location XDH/XOD is also associated to the polysaccharide chains of proteoglycans on the external endothelial cell membrane. In the early stages of acute pancreatitis, this enzyme seems to be arising from its mobilization from the gastrointestinal endothelial cell surface. Taking into account the ability of α-amylase to hydrolyze the internal α-1,4 linkages of polysaccharides, we wanted to elucidate the involvement of α-amylase in XDH/XOD mobilization from the gastrointestinal endothelial cell surface and the relevance of the ascitic fluid (AF) as the source of α-amylase in experimental acute pancreatitis. METHODS: Acute pancreatitis was induced in male Wistar rats by intraductal administration of 5% sodium taurocholate. In another experimental group 3000 U/Kg α-amylase was i.v. administered. The concentrations of XDH, XOD and α-amylase in plasma and AF and myeloperoxidase (MPO) in lung have been evaluated. In additional experiments, the effect of peritoneal lavage and the absorption of α-amylase present in the AF by an isolated intestine have been determined. RESULTS: Similar increase in XDH+XOD activity in plasma was observed after induction of acute pancreatitis and after i.v. administration of α-amylase. Nevertheless, the conversion from XDH to XOD was only observed in the pancreatitis group. Lung inflammation measured as MPO activity was observed only in the pancreatitis group. In addition peritoneal lavage prevented the increase in α-amylase and XDH+XOD in plasma after induction of pancreatitis. Finally, it was observed that α-amylase is absorbed from the AF by the intestine. CONCLUSIONS: During the early stages of acute pancreatitis, α-amylase absorbed from AF through the gastrointestinal tract could interfere with the binding of XDH/XOD attached to glycoproteins of the endothelial cells. Proteolytic enzymes convert XDH into its oxidase form promoting an increase in circulating XOD that has been reported to be one of the mechanisms involved in the triggering of the systemic inflammatory process

Adhesion Molecules Associated with Female Genital Tract Infection

Altres ajuts: Marie Curie Career Integration Grant i una beca Fundació Dexeus Salut de la DonaEfforts to develop vaccines that can elicit mucosal immune responses in the female genital tract against sexually transmitted infections have been hampered by an inability to measure immune responses in these tissues. The differential expression of adhesion molecules is known to confer site-dependent homing of circulating effector T cells to mucosal tissues. Specific homing molecules have been defined that can be measured in blood as surrogate markers of local immunity (e.g. α4β7 for gut). Here we analyzed the expression pattern of adhesion molecules by circulating effector T cells following mucosal infection of the female genital tract in mice and during a symptomatic episode of vaginosis in women. While CCR2, CCR5, CXCR6 and CD11c were preferentially expressed in a mouse model of Chlamydia infection, only CCR5 and CD11c were clearly expressed by effector T cells during bacterial vaginosis in women. Other homing molecules previously suggested as required for homing to the genital mucosa such as α4β1 and α4β7 were also differentially expressed in these patients. However, CD11c expression, an integrin chain rarely analyzed in the context of T cell immunity, was the most consistently elevated in all activated effector CD8+ T cell subsets analyzed. This molecule was also induced after systemic infection in mice, suggesting that CD11c is not exclusive of genital tract infection. Still, its increase in response to genital tract disorders may represent a novel surrogate marker of mucosal immunity in women, and warrants further exploration for diagnostic and therapeutic purposes