1000 resultados para Economia de escala Teses
Resumo:
Polyaniline (PAni) is one of the most studied conducting polymer. It can be synthesized by two methods: electrochemical or chemical oxidation. The chemical oxidation is more adequate to produce large quantities of polymer. Regardless of the synthesis scale, the treatment of the residues before its final destination is very important and necessary because it contains toxic aniline derivatives (carcinogens in some cases), acids and inorganic salts, both with low toxicity. In this work we discuss the methods used to treat these residues and to eliminate and discard the toxic substances. These were extracted from the reaction residues by using activated coal and the pH of the residue was neutralized.
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Algae constitute a large group of many different organisms, essentially aquatic and able to live in all systems giving them sufficient light and humidity. Some algae species have been used in the evaluation or in the bioremediation of aquatic systems. More recently algae have been suggested as interesting tools in the field of analytical chemistry. In this work the most important aspects related to the different uses of algae are presented with a brief discussion.
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The total synthesis of sulfadiazine and silver sulfadiazine from readily available starting materials was adapted to semi-micro laboratory scale and is proposed as an experiment in drug synthesis for undergraduate courses.
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There is great interest nowadays in the use of preparative liquid chromatography as an effective tool for the production of enantiomerically pure, or enriched, compounds for the pharmaceutical industry. To make the chromatographic process economically attractive, attention is now focused on the choice of the chromatographic operating mode to minimize eluent consumption and to maximize productivity. Among the alternatives to the traditional batch chromatography, attention is now shifting towards simulated moving bed (SMB) technologies and a review covering the latest developments in this area seems timely. Several aspects of this important analytical technique are presented and details concerning the SMB technology for process optimization are outlined.
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This paper reviews some of the most usual definitions of stress and trauma including the notion of accumulative trauma. Then, the Spanish version of the Cumulative Trauma Scale by Kira et al (2008) is presented. It has been developed by following a process of translation and by applying it to two small groups of subjects to test it for comprehension (pilot test).
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El passat 12 de desembre, l'Organització per a la Cooperació i el Desenvolupament Econòmic va fer públic un informe que revelava que durant l'any 2004 la Xinava superar els EUA com a lÃder mundial en exportacions de tecnologies de la informació, com ara telèfons mòbils, ordinadors portà tils i cà meres digitals. Aquesta notÃcia, que confirma l'espectacular creixement d'aquest gegant asià tic, m'ha fet reflexionar sobre diversos escrits que he llegit aquest darrer any [...].
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The satisfaction of consumers and users with the products and services is an issue that in recent years has been taking more and more importance and now it even reaches psychotherapy. This paper presents the Spanish adaptation of the Consumer Reports Effectiveness Scale (CRES-4)consisting of four items designed to evaluate whether patients are satisfied with the therapy they have received and if it has been perceived as effective or not. Its global score is intended to reflect treatment effectiveness as percived by the patient. Existing studies suggest that the CRES-4 is a good complementary tool to judge, in particular, satisfaction with treatment received.
Avaliação em escala laboratorial da utilização do processo eletrolÃtico no tratamento de águas
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Water treatment uses chlorine for disinfection causing formation of trihalomethanes. In this work, an electrolytic water pre-treatment was studied and applied to the water from a fountainhead. The action against microorganisms was evaluated using cast-iron and aluminum electrodes. Assays were made in laboratory using the electrolytic treatment. After 5 min of electrolysis the heterotrophic bacteria count was below 500 cfu/mL and complete elimination of total and fecal coliforms was observed. Using electrolytic treatment as a pretreatment of conventional tap water treatment is proposed.
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Psychometric analysis of the AF5 multidimensional scale of self-concept in a sample of adolescents and adults in Catalonia. The aim of this study is to carry out a psychometric study of the AF5 scale in a sample of 4.825 Catalan subjects from 11 to 63 years-old. They are students from secondary compulsory education (ESO), from high school, middle-level vocational training (CFGM) and from the university. Using a principal component analysis (PCA) the theoretical validity of the components is established and the reliability of the instrument is also analyzed. Differential analyses are performed by gender and normative group using a 2 6 factorial design. The normative group variable includes the different levels classifi ed into 6 sub-groups: university, post-compulsory secondary education (high school and CFGM), 4th of ESO, 3rd of ESO, 2nd of ESO and 1st of ESO. The results indicate that the reliability of the Catalan version of the scale is similar to the original scale. The factorial structure also fi ts with the original model established beforehand. Signifi cant differences by normative group in the four components of self-concept explored (social, family, academic/occupational and physical) are observed. By gender, signifi cant differences appear in the component of physical self-concept, academic and social but not in the family component
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Geographical scale is not merely a technical question. The learning of geographical scale goes beyond geometricunderstanding; it implies the etymological comprehension of the concept, the recognition of the importance of scale in theelaboration of the geographical discourse. It implies placing oneself in the centre of the teaching and learning of Geographyand asking oneself, what scale? Why this scale? What progression of scales? The answer to these questions puts in doubtthe scientific discourse that is presently taught in schools especially on the scale of analysis, the sequencing of studiedspaces and the false dichotomy local and global
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The technological advances and new organisation of the economy together with a change in ideas in consumer habits andlifestyle that have happened in the last 25 years have placed us in a new state of capitalism. The spatial translation of thisnew state has been immediate and implies among other changes the overcoming of the concept of scale. Commercialspaces and those of leisure and tourism offer us an unbeatable opportunity of exemplifying these changes because they arethe most effected by the new postmodern tendencies
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In this work the separation of the chiral anesthetic compounds ketamine and bupivacaine was development using two chiral stationary phases (CSP). Ketamine enantiomers were well separate in the polysaccharide-based CSP (microcrystalline cellulose triacetate - MCTA) while bupivacaine in the tartardiamide-based CSP (Kromasil CHI-TBB). In both cases, the effect of temperature was investigated under analytical conditions. An improvement in the separation performance with temperature was observed. Thermodynamic parameters were evaluated by the van't Hoff plot. We concluded that enthalpic effects controlled the retention in these chiral columns. The enantiomers of ketamine and bupivacaine were separated under overloaded conditions with a good performance.
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The cycle of fossil fuels as an energy source for mankind is approaching its end. Finite resources, coupled with greenhouse gas, have led to an increased effort in the search for alternative renewable energy sources. Brazil has a leading position, due to a 46% participation of renewable sources in its primary energy supply, compared to the global average of 12%. The expansion of the renewable sources in Brazil depends on medium and long term planning, and a large volume of investments. The present financial crisis will have major effects in the energy market. Despite a negative initial impact, it is expected that the rearrangement of the financial system will ultimately lead to an expansion in the use of renewable energy sources. Brazil is a tropical country, with the largest biodiversity in our planet and excellent conditions to expand the use of all forms of renewable sources.
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Advanced oxidative processes (AOPs) are based on chemical processes that can generate free radicals, such as hydroxyl radicals (.OH) which are strong, non-selective oxidant species that react with the vast majority of organic compounds. Nanostructured semiconductors, especially titanium dioxide (TiO2) in the anatase phase, are well-established photocatalysts for this process, which have proved to be useful in the degradation of dyes, pesticides and other contaminants. Research in different strategies for the synthesis of nanostructured semiconductors, with particular characteristic is currently a topic of interest in many studies. Thus, this paper presents a review about various synthesis strategies of nanostructured photocatalysts.