Sol-gel derived oxides and mixed oxides catalysts with narrow mesoporous distribution

A novel sol-gel process for preparing oxides and mixed oxides sols from precipitation and peptization process is reported in this article. Inorganic salts are used as raw materials in this study. It is found that the amount of acid has great influence on the stability and particle diameter distribution of the precursor sols. Ultrasonic treatment is used to prepare alumina sol at room temperature. The result of Al-27 NMR shows that there exist Al-13(7+) species in the sol. By controlling the sol particles with narrow particle diameter distribution, alumina, titania and silica-alumina (SA) materials with narrow mesoporous distribution are formed by regular packing of sol particles during gelation without using any templates. The results also show that the structure and particle diameter distribution of precursor sol determine the final materials' texture.

Synthesis and characterization of ZrO2 : Eu nanopowder by EDTA complexing sol-gel method

Nanocrystalline ZrO2:Eu was synthesized by complexing sol-gel method. The effects of heat treatment on structure, grain size and luminescence properties of ZrO2:Eu were studied with X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence measurements. The dependence between the fluorescence emission and the crystalline structure is discussed. (c) 2004 Elsevier B.V. All rights reserved.

CO hydrogenation to light alkenes over Mn/Fe catalysts prepared by coprecipitation and sol-gel methods

CO hydrogenation to light alkenes was carried out on manganese promoted iron catalysts prepared by coprecipitation and sol-gel techniques. Addition of manganese in the range of 1-4 mol.% by means of coprecipitation could improve notably the percentage of C-2 (=) similar to C-4 (=) in the products, but it was not so efficient when the sol-gel method was employed. XRD and H-2-TPR measurements showed that the catalyst samples giving high C-2 (=) similar to C-4 (=) yields possessed ultra. ne particles in the form of pure alpha-(Fe1-xMnx)(2)O-3, and high quality in lowering the reduction temperature of the iron oxide. Furthermore, these samples displayed deep extent of carburization and different surface procedures to the others in the tests of Temperature Programmed Surface Carburization (TPSC). The different surface procedures of these samples were considered to have close relationship with the evolving of surface oxygen. It was also suggested that for the catalysts with high C-2 (=) similar to C-4 (=) yields, the turnover rate of the active site could be kept at a relatively high level due to the improved reducing and carburizing capabilities. Consequently, there would be a large number of sites for CO adsorption/dissociation and an enhanced carburization environment on the catalyst surface, so that the process of hydrogenation could be suppressed relatively to a low level. As a result, the percentage of the light alkenes in the products could be raised.

Development and application of a sol-gel immunosorbent-based method for the determination of isoproturon in surface water

An immunosorbent was fabricated by encapsulation Of monoclonal anti-isoproturon antibodies in sol-gel matrix. The immunosorbent-based loading, rinsing and eluting processes were optimized. Based on these optimizations, the sol-gel immunosorbent (SG-IS) selectively extracted isoproturon from an artificial mixture of 68 pesticides. In addition to this high selectivity, the SG-IS proved to be reusable. The SG-IS was combined with liquid chromatography-tandem mass spectrometry (LC-MS-MS) to determine isoproturon in surface water, and the linear range was up to 2.2 mu g/l with correlation coefficient higher than 0.99 and relative standard deviation (RSD) lower than 5% (n = 8). The limit of quantitation (LOQ) for 25-ml surface water sample was 5 ng/l. (c) 2006 Elsevier B.V. All rights reserved.

Antropologia e psicoterapia

Tese apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Doutor em Ciências Sociais, especialidade em Antropologia

Acculturation and Global Mindsponge

Much research on acculturation around global experiences has focused on the “type” of overseas experience—e.g. expatriate, repatriate, inpatriate, flexpatriate. The experiences of people in those categories and across various demographics (single/married/divorced; gender; sexual orientation) can differ dramatically. In addition, given the explosion of people working in global business, some global business citizens could well fit into several of those various types of experiences over the course of their careers. In this paper, we propose to push in a somewhat different direction and explore something that for us would be quite new. Rather than focusing on the various categories and their resulting experiences, we take a step back to consider what attributes and ways of thinking a global citizen may need to become better as a global business citizen, regardless of type of experience. The question is less one of “Who am I” than “How can I become better?”. Essentially, we would like to explore what might be required in moving the global citizen from thinking about “global mindset” to “global mindsponge.” When we hear the term mindset, we think of a certain way of thinking that stays rather fixed. So part of the challenge of the paper will be to define and examine what mindsponge might mean in the global context—what does it take to unlearn or squeeze out certain ways of thinking or behaving before absorbing and reshaping new ways of thinking and behaving? Moreover, how might that become part of a natural and regular way of operating, especially in a rapidly changing developing country like Vietnam, in particular? At this early stage, we think of mind sponge as a mechanism that encourages flexibility and receptiveness through a process of using multiple filters and more focus on creativity, or doing things differently to improve an organization or individual performance. Our goal is to develop a basic conceptual framework for “mindsponge,” drawing upon a broad literature review as well as several unstructured interviews, to assess whether the idea of mindsponge helps people perceive that they are more culturally versatile and culturally mobile, regardless of whether they work in or outside of their “home environment.” We hope this would enhance their ability to shape an emerging set of cultural values that erases the divide between “foreign” and “local” cultural differences that so often dominates in emerging economies.

Barriers to and facilitators of interventions to counter publication bias: thematic analysis of scholarly articles and stakeholder interviews.

BACKGROUND: When the nature and direction of research results affect their chances of publication, a distortion of the evidence base - termed publication bias - results. Despite considerable recent efforts to implement measures to reduce the non-publication of trials, publication bias is still a major problem in medical research. The objective of our study was to identify barriers to and facilitators of interventions to prevent or reduce publication bias. METHODS: We systematically reviewed the scholarly literature and extracted data from articles. Further, we performed semi-structured interviews with stakeholders. We performed an inductive thematic analysis to identify barriers to and facilitators of interventions to counter publication bias. RESULTS: The systematic review identified 39 articles. Thirty-four of 89 invited interview partners agreed to be interviewed. We clustered interventions into four categories: prospective trial registration, incentives for reporting in peer-reviewed journals or research reports, public availability of individual patient-level data, and peer-review/editorial processes. Barriers we identified included economic and personal interests, lack of financial resources for a global comprehensive trial registry, and different legal systems. Facilitators identified included: raising awareness of the effects of publication bias, providing incentives to make data publically available, and implementing laws to enforce prospective registration and reporting of clinical trial results. CONCLUSIONS: Publication bias is a complex problem that reflects the complex system in which it occurs. The cooperation amongst stakeholders to increase public awareness of the problem, better tailoring of incentives to publish, and ultimately legislative regulations have the greatest potential for reducing publication bias.

A variabel sombra do sol

Este trabauo ten por obxetivo o dar resposta ás duas cuestións seguintes: a) Por que se produce o cambio no tipo de curvatura das sombras dun obxcto nas distintas estacións do ano? b) As curvas descritas polos extremos da sombras son cónicas?. de que tipo? Como case sempre que se emprende unha busca como esta as preguntas anteriores dan pe. como se verá. a introducir outras cuestiona derivadas delas. Compre facer, antes de empezar. unha pequena introducción ao tema que nos ocupa.

Matemáticas aplicadas a la astronomía: tiempo que transcurre entre la salida y la puesta del Sol en los solsticios

En este artículo se resuelve un problema de astronomía mediante la utilización de la trigonometría elemental y del espacio euclideo tridimensional. Se aspira tener una idea de cómo varía la luz solar en los solsticios a lo largo de las latitudes de nuestro planeta, de polo a polo, y se concluye con un programa informático y una tabla para las latitudes de varias ciudades del mundo.