1000 resultados para Química-Problemas


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Ao longo dos anos o desenvolvimento industrial trouxe uma crescente geração de resíduos, que são potenciais problemas ambientais. Estudos das características destes materiais, bem como o desenvolvimento de técnicas para sua utilização se tornam imprescindíveis para a preservação do meio ambiente. Assim este trabalho objetiva a caracterização e utilização de cinza volante proveniente da queima de carvão mineral em caldeiras, assim como o uso de microssílica, utilizada para alterar a relação molar Si/Al da mistura cinza/microssílica na síntese de zeólitas. Para a caracterização da cinza foram utilizados métodos de análise química, física e mineralógica como: difração de raios X, fluorescência de raios X, microscopia eletrônica de varredura, análise granulométrica, análise térmica diferencial e termogravimétrica. Os ensaios de síntese foram feitos a 60, 100, 150 e 190 °C, com razão molar de Na2O/Al2O3 igual a 5 e Si/Al variando de 2,12 a 15, e tempo de reação 24 h. Os resultados da caracterização da cinza mostram potencial utilização deste como matéria-prima para a síntese de zeólitas, pois apresenta ~ 50% de SiO2 e Al2O3, fases mineralógicas bem definidas, baixo teor de umidade, baixa granulometria (d90 < 10 µm), entre outros. Análises de difração de raios X dos produtos das sínteses mostraram a formação de alguns tipos de zeólitas, como analcima, phillipsita, sodalita, zeolita P e tobermorita. Deste modo, a mistura cinza e microssílica nestas condições reacionais mostram-se matérias-primas promissoras para a síntese de zeólitas.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Dissatisfaction with certain aspects of the educational processes of the traditional teaching has always existed, and new teaching methods have been routinely studied. The experimental investigative activity is one of those alternative practices. In this type of activity the experimentation is inserted with an investigative approach, in which the student must build the concept, with proposals that represent solutions to the excited problems. In the teaching of chemistry, specifically, the need and importance of experimentation is evident, beyond motivate students, aid in the understanding of chemical concepts relating them to reality. Realizing the contributions of this methodology for teaching and learning, through this research was conducted to understand the difficulties encountered by teachers for planning and implementation of these activities in the teaching of chemistry and therefore the reasons for the dominance of traditional teaching method. The subjects were undergraduate students of chemistry course that developed and implemented differentiated learning activities for teaching and teachers who accompanied the high school students who participated in the university extension project Inclusion Science and University students and teachers from public: Teaching and Learning Chemistry focuses on research and practice”. Through the data it was possible to identify some factors that affect and hinder the implementation of experimental activities in general, not only the investigative. However, despite the difficulties experienced by undergraduates, the majority considered the activity as an alternative teaching method interesting and innovative, able to produce interest, motivation and participation of students with subsequent learning. As well as the teachers, what with all the difficulties that they had declared facing when applying experimental activities, they admitted the pedagogical... (Complete abstract click electronic access belo)

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The development of human societies and their activities generate many impacts on the environment and natural resources. The consequence of these problems is a disturbance of the systemic dynamics of Planet Earth. Study these impacts are a way to understand the workings of this system and undertake efforts to prevent minimize and anticipate scenarios caused by environmental impacts. In this sense, from a systemic approach seeks to understand the way how is the interaction of the components of the ecosystems, adopting for this task the hydrographic basin as a natural unit of planning and management in view of the fact all landscape elements (atmosphere, hydrosphere, biosphere and geosphere) interact so that the reflections of human activities can be represented in this unit. Thus, this study aims to quantify chemical erosion rates in the hydrographic basin of Ribeirao Monjolo Grande, Ipeúna (SP), which is relevant to analyze the geomorphological characteristics of the area, which may serve to better exploitation of natural resources

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The educational institutions need to rethink issues related to teacher training in order to seek personal construction of teaching. Oriented research has been identified as useful in the process of teacher training. Through research builds knowledge about the problems faced in teaching, producing the most effective methods. The aim of this paper is to verify the validity of the application of research activities in the form of short courses and themed play during the formation of licensees and the use and construction of knowledge of high school students who attended these short courses. This work is linked to training of undergraduates and implementation of different activities of teaching and learning for high school students. The oriented investigation was the methodology chosen for the development of activities in which, through the construction and implementation of the mini-courses Students are encouraged to participate in the construction of knowledge itself in activities that suggest the development and testing of hypotheses. The mini-courses are designed and implemented by teachers of the ninth and tenth terms of the degree in chemistry. Students of public schools were the privileged. Data were collected through observation and interview. In applying these mini-courses, associated with the daily, prospective teachers connected theory to practice, arousing the curiosity of students and leading them to raise issues related to the content of chemistry. Students showed interest in the construction of the content addressed. The student teachers sought to study different concepts and how to make them more attractive, causing the chemistry was associated with the phenomena of everyday life, including the problems faced when teaching and trying different possible solutions. Thus, there was an increase in interest in teaching and learning

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Abstracts of scientific articles offer the first contact their readers have with the issues and results presented by the article, thus having a pivotal screening role. Due to their importance, they need to be well written, taking into account their genre-specific rules. Several studies have aimed at describing its particular textual structure, its rubric, though there is still much data to be amassed. The purpose of this work was to analyze a corpus of Chemistry abstracts, seeking the rhetoric categories that structure them in the sentence level and to describe its rubric. In order to do that, we have used lexical and grammatical evidence to categorise the rhetoric role each sentence has. We have found that the expected structure occurs, the main rhetoric focus being the presentation of results in the vast majority of cases. Furthermore, the occurrence of certain categories may depend on the size of the abstract, and certain rhetoric roles are embedded in others, especially the one describing method. The corpus has yet to be expanded to offer further results, two of them being to help non-native writers to better structure the textual level of their works and to build a software of automatic analysis of abstracts

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Drug addiction is one of the biggest public health problems worldwide, not only by the dimensions of the problem, but also by the severity of the damage, creating favorable conditions for opportunistic microorganisms such as class Mollicutes. This study aims to evaluate the presence of the main species and genera of this group in the subgingival biofilm of drug addiction patients, comparing them with non-dependent subjects. For this purpose, data on systemic health conditions, socioeconomic characteristics, drug addiction from 72 patients with drug addiction kept in rehab clinics and 100 non-dependent patients who formed the control group were obtained. Intra and extraoral clinical examinations were performed and samples of subgingival plaque were collected through sterile absorbent paper cones. The presence of different genera and species of the class Mollicutes was evaluated by PCR using the specific primers and conditions for each microorganism. The statistical analysis was performed using the Chi-square test for comparisons of three or more variables and the Mann-Whitney test, with significance level of 5%. Out of species and genera evaluated, Mycoplasma salivarium showed correlation with gingival inflammation in both patient groups and was more frequently detected among drug addiction patients

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Pós-graduação em Agronomia (Horticultura) - FCA

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)