Chemical Stability of Mesoporous Oxide Thin Film Electrodes under Electrochemical Cycling: from Dissolution to Stabilization

Mesoporous oxide thin films (MOTF) present very high surface areas and highly controlled monodisperse pores in the nanometer range. These features spurred their possible applications in separation membranes and permselective electrodes. However, their performance in real applications is limited by their reactivity. Here, we perform a basic study of the stability of MOTF toward dissolution in aqueous media using a variety of characterization techniques. In particular, we focus in their stability behavior under the influence of ionic strength, adsorption of electrochemical probes, and applied electrode potential. Mesoporous silica thin films present a limited chemical stability after electrochemical cycling, particularly under high ionic strength, due to their high specific surface area and the interactions between the electrochemical probes and the surface. In contrast, TiO2 or Si0.9Zr0.1O2 matrices present higher stability; thus, they are an adequate alternative to produce accessible, sensitive, and robust permselective electrodes or membranes that perform under a wide variety of conditions.Fil: Alberti, Sebastián. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Steinberg, Paula Yael. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Giménez, Gustavo Néstor. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Amenitsch, Heinz. Graz University Of Technology.; AustriaFil: Ybarra, Gabriel Omar. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Azzaroni, Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Angelome, Paula Cecilia. Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología; ArgentinaFil: Soler Illia, Galo Juan de Avila Arturo. Universidad Nacional de San Martin. Instituto de Nanosistemas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Chemical Stability of Mesoporous Oxide Thin Film Electrodes under Electrochemical Cycling: from Dissolution to Stabilization

Mesoporous oxide thin films (MOTF) present very high surface areas and highly controlled monodisperse pores in the nanometer range. These features spurred their possible applications in separation membranes and permselective electrodes. However, their performance in real applications is limited by their reactivity. Here, we perform a basic study of the stability of MOTF toward dissolution in aqueous media using a variety of characterization techniques. In particular, we focus in their stability behavior under the influence of ionic strength, adsorption of electrochemical probes, and applied electrode potential. Mesoporous silica thin films present a limited chemical stability after electrochemical cycling, particularly under high ionic strength, due to their high specific surface area and the interactions between the electrochemical probes and the surface. In contrast, TiO₂ or Si0.9Zr0.1O₂ matrices present higher stability; thus, they are an adequate alternative to produce accessible, sensitive, and robust permselective electrodes or membranes that perform under a wide variety of conditions.Facultad de Ciencias ExactasInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Chemical composition and digestion of shurbs browsed by white-tailed deer (odocoileus virginianus texanus)

The aim of the study was to determine, seasonally, the nutritional value of the native shrubs: Acacia amentacea, Castela erecta, Celtis pallida, Croton cortesianus, Forestiera angustifolia, Karwinskia humboldtiana, Lantana macropoda, Leucophyllum frutescens, Prosopis laevigata, Syderoxylon celastrinum and Zanthoxylum fagara. Leave samples were collected seasonally during 2 years from Summer 2004 to Spring 2006 in three county sites: China, Linares and Los Ramones in the state Nuevo Leon, Mexico and evaluated for the content of their Crude Protein (CP), Neutral Detergent Fiber (NDF) and Acid Detergent Lignin (ADL). Dry Matter Digestibility (DMD) was also estimated. The CP content (range of total means = 13-22% dry matter) in most plants significantly varied among sites and seasons and between years. The same pattern occurred for NDF (40-55), ADL (8-22) and DMD (48-73). Celtis pallida had the highest nutritional value. However, due to their high CP and DMD and low NDF and ADL all studied plants in all sites, most seasons and years may be considered as good food sources for white-tailed deer

Macro Mineral Content in Five Shrubs Browsed by White-Tailed Deer (Odocoileus virginianus), Northeastern Mexico

The Ca, K, Mg, Na and P contents were determined, seasonally during 2 consecutive years in leaves of native browse plants such as Castela erecta Turp sp. Texana (Torr & A. Gray) Cronquist (Simaroubaceae), Celtis pallida Torr. (Ulmaceae), Forestiera angustifolia Torr. (Oleaceae), Lantana macropoda Torr. (Verbenaceae) and Zanthoxylum fagara (L.) Sarg (Rutaceae) that were collected from August 2004 to May 2006 in a semiarid and subtropical area of the State of Nuevo Leon, Mexico at three county (Los Ramones, China and Linares) sites which are grouped under a similar climatic pattern. Mineral contents were measured using an atomic absorption spectrophotometer with exception of P content that was estimated using a colorimeter. All minerals in all species were significantly different among years, sites and seasons and interactions were also significant. In general, plants at Linares site which historically registered the highest rainfall had higher mineral content followed by Los Ramones and China. Moreover, during the 2nd year, all plants species showed higher mineral content than the 1st year. Furthermore, during the Summer session, all plants species had higher mineral content followed by Autumn, Winter and Spring. Regardless of spatio-temporal differences, all plant species had suitable levels of Ca, Mg and K to satisfy range domestic and wild ruminant requirements. In contrast, P and Na contents showed marginal inadequacies in some seasons throughout the year. Seasonal variations in minerals could be associated to climatic conditions like excessive irradiance levels during Summer and extreme low temperatures in Winter and rainfall events

Panorama das Intervenções Coronárias Percutâneas em Oclusões Totais Crônicas em Centros Participantes do LATAM CTO Registry no Brasil

Background: Major advances have been seen in techniques and devices for performing percutaneous coronary interventions (PCIs) for chronic total occlusions (CTOs), but there are limited real-world practice data from developing countries. Objectives: To report clinical and angiographic characteristics, procedural aspects, and clinical outcomes of CTO PCI performed at dedicated centers in Brazil. Methods: Included patients underwent CTO PCI at centers participating in the LATAM CTO Registry, a Latin American multicenter registry dedicated to prospective collection of these data. Inclusion criteria were procedures performed in Brazil, age 18 years or over, and presence of CTO with PCI attempt. CTO was defined as a 100% lesion in an epicardial coronary artery, known or estimated to have lasted at least 3 months. Results: Data on 1196 CTO PCIs were included. Procedures were performed primarily for angina control (85%) and/or treatment of moderate/severe ischemia (24%). Technical success rate was 84%, being achieved with antegrade wire approaches in 81% of procedures, antegrade dissection and re-entry in 9%, and retrograde approaches in 10%. In-hospital adverse cardiovascular events occurred in 2.3% of cases, with a mortality rate of 0.75%. Conclusions: CTOs can be treated effectively in Brazil by using PCI, with low complication rates. The scientific and technological development observed in this area in the past decade is reflected in the clinical practice of dedicated Brazilian centersinfo:eu-repo/semantics/publishedVersio

Comparación entre dos modelos diferentes de cámaras de McMaster empleadas para el conteo coproscópico en el diagnóstico de infecciones por nematodos gastroentéricos en rumiantes

Gastrointestinal parasitism in ruminants, represents a major constraint to growth, reproduction and survival in susceptible animals. The control of parasitic infections need of techniques able to determine the presence of the parasite and the infestation levels within the herd in order to establish the possible relationship among the physiologic alterations, the level of parasitic infection and the affection on the production. The aims of this work, was to compare the classical coproscopical technique of McMaster (TCC) against the McMaster INTA (TCI) technique, both are eggs counting slide used for the parasitological diagnosis. For the study 40 crossbreed calves of both sexes were used. A total of 40 samples of faeces were gathered directly of the rectum of each animal and examined for both techniques. The comparison between the eggs per gram of faeces counts (HPG) was realized by mean of Wilcoxon test and the correlation through the coeffi cient of ranks of Spearman. The comparison of the discrepancies was made with the McNemar test and the agreement was evaluated with the Kappa Index. We conclude that both cameras have features of reliability, speed, simplicity and low cost, but the TCI offers advantages in detection of eggs (positive animals) and accumulators animal identification.El parasitismo gastrointestinal en rumiantes, representa una importante limitante del crecimiento, reproducción y supervivencia en animales susceptibles. Para su control debe disponerse de técnicas diagnósticas capaces de determinar la presencia del parásito, los niveles de infección y permitir inferir en base a estos resultados, elestado de alteraciones fi siológicas y el grado de afección sobre factores de importancia en la producción que estas generan. El objetivo de este trabajo consistió en comparar la efi cacia de dos cámaras diseñadas para el conteo coproscópico de huevos de estróngilos digestivos. Para el estudio se emplearon 40 becerros mestizos de ambos sexos, de los cuales se recolectaron 40 muestras de heces directamente del recto de cada animal para su posterior procesamiento por las técnicas de McMaster clásica modificada (TCC) que consta de dos compartimientos y requiere de una muestra de 3 g de heces, y la técnica de McMaster modifi cada empleando la cámara INTA (TCI), que posee 4 compartimientos y requiere de una muestra de 5 g de heces. Para la comparación entre los recuentos de huevos de estróngilos digestivos por gramo de heces (HPG) se empleó la prueba de Wilcoxon y la correlación mediante el coeficiente de rangos de Spearman. La comparación de las discrepancias se hizo con la prueba de McNemar y la concordancia con el Índice de Kappa. Se concluye que ambas cámaras poseen características de confiabilidad, rapidez, sencillez y bajo costo, sin embargo, la TCI ofrece ventajas en cuanto detección de huevos (animales positivos) e identificación de animales acumuladores

Preparation of mesoporous silica thin films at low temperature: a comparison of mild structure consolidation and template extraction procedures

Mesoporous thin films (MTFs) displaying high surface area and controlled porosity constitute interesting materials for a plethora of applications in optics and electronics. A critical aspect in MTF processing is template removal that usually consists in thermal treatment at 350 °C, which consolidates the oxide film but might change the pore features. In addition, the use of such high temperature must be avoided when organic functionalities are to be preserved, or in the case of film deposition on polymeric substrates. Here we present and compare five different methods to consolidate silica MTF (SMTF) in mild conditions, at a maximum processing temperature of 130 °C. Conditions, such as duration of the thermal treatment, vacuum conditions, exposure to acidic and alkaline media, were systematically explored and the resulting films were analyzed by optical microscopy, focused ion beam, scanning electron microscopy, ellipsometry, and infrared spectroscopy. The optimized conditions leading to accessible mesopores and a stable oxide structure that can be used as a mesoporous perm-selective electrode are discussed.Fil: Giménez, Gustavo Néstor. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario; ArgentinaFil: Ybarra, Gabriel Omar. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario; ArgentinaFil: Soler Illia, Galo Juan de Avila Arturo. Universidad Nacional de San Martin. Instituto de Nanosistemas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Nanomaterial-based Multifunctional Inks for the Fabrication of printed Biosensors

Biosensors are increasingly used as low-cost, selective and highly sensitive laboratory and point-of-care devices. In this framework, both nanomaterials and printing techniques have the ability to trigger their enormous potential. The aim of this chapter is to review the application of nanodispersions in ink formulations in order to confer specific properties to printed layers regarding the fabrication of biosensors. Such properties are optimal immobilization/stabilization of biological recognition elements, electrical conduction, optical properties, selective adsorption of analytes and catalysis. This review will include commercial inks, scientific articles and patents. Focusing mainly on optical and electrochemical biosensors, different issues will be covered: from ink formulation (i.e.: stabilization of nanodispersions, water and solvent-based inks) to device prototyping and analytical performance of state-of-the art devices.Fil: Veiga, Lionel S.. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Garate, Octavio Federico. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Gimenez, Gustavo. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Ybarra, Gabriel Omar. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Monsalve, Leandro Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Industrial; Argentin

Exhibition, difference and the logic of culture

A good deal of contemporary museum theory and practice has concerned itself with the ways in which museum environments - and the social and symbolic exchanges that take place within them - might be refashioned so as to transform museums into “differencing machines” committed to the promotion of cross-cultural understanding, especially across divisions that have been racialized. The question I want to pose here is whether this aspiration involves a series of collateral changes that, taken together, add up to a more general change in how museums operate and their situation within the cultural field. To put the point more rhetorically, does the conception of the museum as a “differencing machine” aspire to new forms of dialogism that place earlier notions of exhibition into question? I want also to review, and qualify, the concept of the “exhibitionary complex” by arguing the need to view the operations of this complex in the broader perspective of what, for the purposes of my argument here, I shall call the “logic of culture.” Before I come to either of these questions, however, I want to worry away a little at what is involved in pursuing these concerns in a context defined by a conjunction of “public cultures” and “global transformations” and the ways in which these evoke the concepts of globalization and the public sphere (or spheres) even while distancing themselves from such concepts. The consequences for how we engage with the changing role of museums can vary significantly depending on how each of these terms is interpreted and how the relations between them are viewed. And each has the potential to significantly misdirect inquiry