993 resultados para Primary Drivers


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This paper presents a new strategy, “state-by-state transient screening”, for kinetic characterization of states of a multicomponent catalyst as applied to TAP pulse-response experiments. The key idea is to perform an insignificant chemical perturbation of the catalytic system so that the known essential characteristics of the catalyst (e.g. oxidation degree) do not change during the experiment. Two types of catalytic substances can be distinguished: catalyst state substances, which determine the catalyst state, and catalyst dynamic substances, which are created by the perturbation. The general methodological and theoretical framework for multi-pulse TAP experiments is developed, and the general model for a one-pulse TAP experiment is solved. The primary kinetic characteristics, basic kinetic coefficients, are extracted from diffusion–reaction data and calculated as functions of experimentally measured exit-flow moments without assumptions regarding the detailed kinetic mechanism. The new strategy presented in this paper provides essential information, which can be a basis for developing a detailed reaction mechanism. The theoretical results are illustrated using furan oxidation over a VPO catalyst.

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The state-by-state transient screening approach based on a pulse-response thin-zone TAP experiment is further developed whereby single-pulse kinetic tests are treated as small perturbations to catalyst compositions and analyzed using integral method of moments. Results on three primary kinetic characteristics, termed basic kinetic coefficients, are presented. These three coefficients were introduced as main observables from experimentally measured TAP-responses in a kinetic-model-free manner. Each was analytically determined from moments of responses with no assumption about the detailed kinetic model. In this paper, the inverse question of how well these coefficients represent the time evolution of the observed responses is addressed. Sets of three basic kinetic coefficients are calculated from model and experimental responses and these calculated values are used to generate 3-coefficient curves in a kinetic-model-free manner. The comparison of these 3-coefficient curves with original responses shows that three basic kinetic coefficients can be sufficient to describe the observed kinetics of exit flow time dependencies with no assumption regarding the detailed kinetic model.

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The aim of this paper is to recognize the images that prospective elementary school teachers have about citizenship and citizenship education in school. The qualitative methodology with an ethnographic approach is used for that deep interview of ethnographic kind and analysis of institutional documents, for example, curricula, course syllabus and graduated profi le. The revision of documents helps to a better understanding of discourses. The analysis of the corpus obtained after the application of the paradigm of codifi cation proposed in the established theory. As the principal fi ndings we way point out that the concept of citizens that is common among prospective elementary school teachers is reduced to the school environment because they consider that the promotion of citizenship helps to the incorporation of children to society, thus reproducing a propaedeutic view of education.

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%0 per cent of antibiotic use in the community is for respiratory infection. this editorial considers wwh 8 out of 10 consultations for cough in general practice result inantibiotic prescribing