On the nature of the silver phases of Ag/Al2O3 catalysts for reactions involving nitric oxide

The nature of the silver phases of Ag/Al2O3 catalysts (prepared by silver nitrate impregnation followed by calcination) was investigated by X-ray diffractograms (XRD), transmission electron microscopy (TEM) and UV-VIS analyses and related to the activity of the corresponding materials for the oxidation of NO to NO2. The UV-VIS spectrum of the 1.2 wt.% Ag/Al2O3 exhibited essentially one band associated with Ag+ species and the NO2 yields measured over this material were negligible. A 10 wt.% Ag/Al2O3 material showed the presence of oxidic species of silver (as isolated Ag+ cations and silver aluminate), but the UV-VIS data also revealed the presence of some metallic silver. The activity for the NO oxidation to NO2 of this sample was moderate. The same 10% sample either reduced in H-2 or used for the C3H6-selective catalytic reduction (SCR) of NO showed a significantly larger proportion of silver metallic phases and these samples displayed a high activity for the formation of NO2. These data show that the structure and nature of the silver phases of Ag/Al2O3 catalysts can markedly change under reaction feed containing only a fraction of reducing agent (i.e. 500 ppm of propene) in net oxidizing conditions (2.5% O-2). The low activity for N-2 formation during the C3H6-SCR of NO (reported in an earlier study) over the high loading sample can. therefore, he related to the presence of metallic silver. which is yet a good catalyst for NO oxidation to NO2. The reverse observations apply for the oxide species observed over the low loading sample, which is a good SCR catalyst but do not oxidize NO to NO2. (C) 2002 Elsevier Science B.V. All rights reserved.

Paul Karl Feyerabend Las proyecciones de la proliferación teórica en la relación ciencia-metafísica

La doctrina de la Proliferación teórica de Paul Karl Feyerabend ha sido interpretada por sus especialistas como un intento de salvaguardar el ideal del progreso científico. Aunque tales estudios hacen justicia, en parte, a la intencionalidad de nuestro filósofo no explicitan la crítica fundamental que implica para Feyerabend el pluralismo teórico. La proliferación teórica constituye en sí misma una reductio ad absurdum de los distintos intentos del positivismo lógico y del racionalismo crítico por definir la ciencia a expensas de lo metafísico. Este artículo presenta la proliferación teórica como una reivindicación del papel positivo que ocupa la metafísica en el quehacer científico. Se consigna la defensa que hace Feyerabend de la metafísica en cuanto que ésta constituye la posibilidad de superar el conservadurismo conceptual, aumentar de contenido empírico de la ciencia y recuperar el valor descriptivo de las teorías científicas.

Increased cerebral output of free radicals during hypoxia: implications for acute mountain sickness?

Bailey DM, Taudorf S, Berg RMG, Lundby C, McEneny J, Young IS, Evans KA, James PE, Shore A, Hullin DA, McCord JM, Pedersen BK, Moller K. Increased cerebral output of free radicals during hypoxia: implications for acute mountain sickness? Am J Physiol Regul Integr Comp Physiol 297: R1283-R1292, 2009. First published September 2, 2009; doi: 10.1152/ajpregu.00366.2009.-This study examined whether hypoxia causes free radical-mediated disruption of the blood-brain barrier (BBB) and impaired cerebral oxidative metabolism and whether this has any bearing on neurological symptoms ascribed to acute mountain sickness (AMS). Ten men provided internal jugular vein and radial artery blood samples during normoxia and 9-h passive exposure to hypoxia (12.9% O-2). Cerebral blood flow was determined by the Kety-Schmidt technique with net exchange calculated by the Fick principle. AMS and headache were determined with clinically validated questionnaires. Electron paramagnetic resonance spectroscopy and ozone-based chemiluminescence were employed for direct detection of spin-trapped free radicals and nitric oxide metabolites. Neuron-specific enolase (NSE), S100 beta, and 3-nitrotyrosine (3-NT) were determined by ELISA. Hypoxia increased the arterio-jugular venous concentration difference (a-v(D)) and net cerebral output of lipid-derived alkoxyl-alkyl free radicals and lipid hydroperoxides (P

Observation of the transient charging of a laser-irradiated solid

The proton radiography technique has been used to investigate the incidence of a 3 x10(19) W/cm(2) infrared pulse with a 125 mu m-diameter gold wire. The laser interaction is observed to drive the growth of a radial electric field similar to 10(10) V/m on the surface of the wire which rises and decays over a temporal window of 20 ps. Such studies of the ultrafast charging of a solid irradiated at high-intensity may be of relevance to schemes for laser-driven ion acceleration and the fast-ignitor concept for inertial confinement fusion.

The immediate Life support course: implementation into an undergraduate nursing programme

This paper outlines how the immediate life support (ILS) course was incorporated into an undergraduate-nursing curriculum in a university in Northern Ireland. It also reports on how the students perceived the impact of this course on their clinical practice. The aim was to develop the student’s ability to recognise the acutely ill patient and to determine the relevance of this to clinical practice. Prior to this the ILS course was only available to qualified nurses and this paper reports on the first time students were provided with an ILS course in an undergraduate setting. The ILS course was delivered to 89 third year nursing students (Adult Branch) and comprised one full teaching day per week over two weeks. Recognised Advanced Life Support (ALS) instructors, in keeping with the United Kingdom Resuscitation Council guidelines, taught the students. Participants completed a 17 item questionnaire which comprised an open-ended section for student comment. Questionnaire data was analysed descriptively using SSPSS version 15.0. Open-ended responses from the questionnaire data was analysed by content and thematic analysis. Results Student feedback reported that the ILS course helped them understand what constituted the acutely ill patient and the role of the nurse in managing a deteriorating situation. Students also reported that they valued the experience as highlighting gaps in their knowledge Conclusion. The inclusion of the ILS course provides students with necessary skills to assess and manage the deteriorating patient. In addition the data from this study suggest the ILS course should be delivered in an inter-professional setting – i.e taught jointly with medical students. References: Department of Health & Quality Assurance Agency (2006). Department of Health Phase 2 benchmarking project – final report. Gloucester: Department of Health, London and Quality Assurance Agency for Higher Education

Study of the images for the Visual Arts Education in Secondary Education textbooks: educational implications

In this paper we present the first data from the research conducted to determine the relationship between traditional visual arts and other forms of visual culture closer to the experiences of high school youth. The hypothesis of this research is that while students are nurtured and live primarily with the images provided by the media culture, their textbooks basically refer to the more traditional art images. The research has been limited to a review and analysis of the most common educational materials for teaching visual arts in high school. After the systematization and analysis of the images appeared in textbooks, we have detected three major types: the artistics, those who belong to media culture and others. The most relevant conclusions indicate that: there are hardly any connections between different types of images, they offer a very traditional view of art and they are far removed from the experiences of young book users.

The Architecture of Seduction: An Analysis on Digital Architectures within Consumer Society

Currently new digital tools used in architecture are often at the service of a conception of architecture as a consumer society’s cultural good. Within this neoliberal cultural frame, architects’ social function is no longer seen as the production of urban facts with sense of duty, but as a part within the symbolic logic that rules the social production of cultural values as it was defined by Veblen and developed by Baudrillard. As a result, the potential given by the new digital tools used in representation has shifted from an instrument used to verify a built project to two different main models: At the one hand the development of pure virtual architectures that are exclusively configured within their symbolic value as artistic “images” easily reproducible. On the other hand the development of all those projects which -even maintaining their attention to architecture as a built fact- base their symbolic value on the author’s image and on virtual aesthetics and logics that prevail over architecture’s materiality. Architects’ sense of duty has definitely reached a turning point.

El artista contemporáneo ante la transformación de su obra. El paso del tiempo y su efecto sobre la significación de la materia

El paso del tiempo tiene una repercusión inevitable sobre las obras de arte. En el caso del arte contemporáneo muchos de los valores estéticos, culturales o sociales presentes en las mismas, están vinculados a la apariencia y al uso premeditado de la materia. La transformación de la materia tiene una repercusión sobre la intención y el discurso estético, por ello, y ante la imposibilidad de impedir el cambio, se hace necesaria una profunda reflexión sobre el concepto de autenticidad de la obra de arte y sobre el concepto de ruina prematura. Por otro lado, gracias a la figura del artista contemporáneo es posible documentar la producción actual para determinar si la mutación de la materia afectará a lo esencial en las obras. En este sentido, el trabajo ha conseguido concretar, para el caso de varios artistas fundamentales del panorama español, qué aspectos deben, por ser esenciales, permanecer inmutables con el paso del tiempo.

CCL11 blocks IL-4 and GM-CSF signaling in hematopoietic cells and hinders dendritic cell differentiation via suppressor of cytokine signaling expression

The chemokine eotaxin/CCL11 is an important mediator of leukocyte migration, but its effect on inflammatory cytokine signaling has not been explored. In this study, we find that CCL11 induces suppressor of cytokine signaling (SOCS) 1 and SOCS3 expression in murine macrophages, human monocytes, and dendritic cells (DCs). We also discover that CCL11 inhibits GM-CSF-mediated STAT5 activation and IL-4-induced STAT6 activation in a range of hematopoietic cells. This blockade of cytokine signaling by CCL11 results in reduced differentiation and endocytic ability of DCs, implicating CCL11-induced SOCS as mediators of chemotactic inflammatory control. These findings demonstrate cross-talk between chemokine and cytokine responses, suggesting that myeloid cells tracking to the inflammatory site do not differentiate in the presence of this chemokine, revealing another role for SOCS in inflammatory regulation. J. Leukoc. Biol. 85: 289-297; 2009.