Repositório RCAAP

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This thesis presents the use of ultrasonic radiation for the digestion of biodiesel samples (B100) for the determination of metal ions by electrochemical stripping techniques (potentiometric and voltammetric) using a glassy-carbon electrode modified with a mercury film. Biodiesel samples (50 mg) were subjected to digestion in glass tubes with a mixture of 3.0 mL of concentrated HCl and 4.4 ml H2O2 (30%), placed in an ultrasonic bath (40 kHz and 120 W) exactly on the higher intensity region (piezoelectric) of the ultrasound and sonicated for 40 min at room temperature (~ 20°C). These parameters were optimized using the chemometric technique of factorial design for the analysis of biodiesel samples spiked with ethanolic standard solutions of zinc, cadmium, lead and copper. Recovery values between 97 and 107% were observed in the optimal conditions found to zinc, cadmium, lead and copper. Residual carbon content (RCC) values after digestions were in the range of 3.05 to 3.75%. The simultaneous determination of zinc, cadmium, lead and copper using anodic stripping voltammetry revealed limit of detection (LD) values of 44 ng kg -1; 30 ng kg -1; 145 ng kg -1; 96 ng kg -1, respectively. Additionally, biodiesel samples (100 mg) were also treated in glass tubes with a mixture of 1.59 mL concentrated HCl and 3.0 ml H2O2 (30%) under sonication of an ultrasonic probe (sonication time 12.5 min, 25% amplitude, pulse of 5.0 s and time interval of 2.0 s). The parameters were also optimized employing the chemometric technique of factorial design for the analysis of spiked samples. Recovery values between 95 and 104% were observed in the satisfactory condition for zinc, cadmium, lead and copper. RCC values after digestions comprised values between 0.43 to 0.54%. For the simultaneous determination of zinc, cadmium, lead and copper using anodic stripping voltammetry obtained in the digestates employing the ultrasonic probe, the LD values found respectively for zinc, cadmium and copper were 25 ng kg -1 and for lead 56 ng kg -1. All results obtained using assisted digestion by ultrasonic bath and / or ultrasonic probe indicate that the proposed methods for the biodiesel sample preparation presents a comparable performance to traditional methods of digestion using acid blends, or yet digestions assisted by microwave radiation.

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The Jatropha curcas is an oilseed with large potential for production of vegetable oil and adjust very well to Brazilian`s climate and soil, including the region of the Caatinga. This study evaluates different forms of oil production and extraction of biodiesel from crude Jatropha curcas oil (OPMB). Extraction tests were carried out with different solvents, showing that the use of ethanol increases the process efficiency process from 36% to 39% in mass. Furthermore, the use of acid catalysis during the solvent extraction reduces the oil`s acidity from 25.93 mg KOH/g to 0.52 mg KOH/g . Using the OPMB as start material in a fractional factorial design and central composite design (CCD) to optimize the reaction conditions for production of biodiesel from Jatropha curcas (BMPM) optimized through the two-step catalysis, optimizing each step separately. In esterification (1st Step) the following variables were evaluated: Temperature (TP), Time reaction (TR), % H2SO4, Molar ratio (alcohol:oil) (RM), Alcohol type (TA) and Rotation speed (VR). The study obtained a maximum point at the central composite design (CCD), determining the best conditions to esterify the OPMB in: TP of 57.3 oC, TR of 173 minutes, 0.5% H2SO4 (w/w), RM (alcohol: oil) of 11.4: 1, methanol as TA and VR 400 rpm, producing a treaty Jatropha curcas oil (OPMT) with acidity at 0.49 mg KOH/g. Then was also optimized the transesterification reaction (2nd step) of OPMT evaluating the variables: TA, TP, RM, TA and % de KOH, obtaining a maximum yield of 97.3% under the following conditions: methanol as TA, TP 35 oC, RM of 10,0: 1, TR 49.8 minutes and 1.26% of KOH. Also are produced, heterogeneous catalysts from recyclable material, expanded polystyrene sulfonated (PSES) and sulfonated polyvinyl chloride (PVCS) that showed 0.43 and 0.32 mmol of acid groups/g, respectively. Using the heterogeneous catalysts in optimized conditions to esterify the OPMB a percentage of esterification (% E) of 93.33% for the PSES and 91.45% for PVCS. The biodiesels were prepared from OPM treated with: H2SO4, PSES and PVCS in optimized conditions, determining your physicochemical properties. The quality of the biodiesels obtained in this study was assessed by parameters established by ANP, observing that Jatropha curcas is a viable option for use as a raw material to product this biofuel.

In this work the cellulose acetate produced by homogeneous acetylation of cellulose extracted from corn stover was used to produce model systems for controlled release of Naproxen in the form of membranes and microparticles. The commercial cellulose diacetate was used as standard material in the production of membranes, and microparticles. The triacetates hydrolyzed and unhydrolyzed cellulose produced from corn stover presented degree of substitution of 2.53 ± 0.16 and 2.79 ± 0.35 respectively. The membranes were produced using the formulation acetate / solvent/naproxen to symmetric membranes acetate/solvent/water/naproxen for asymmetric membranes. The materials were characterized by scanning electron microscopy, differential scanning calorimetry and thermogravimetry, and was later evaluated the drug release kinetics. The hydrolysis process for obtaining corn straw triacetate impaired physical stability of the matrices produced with this derivative, which showed extremely fragile and brittle, making it unsuitable for use in controlled release systems. The release assays were performed with unhydrolyzed triacetate and commercial systems diacetate and the percentage of naproxen released was obtained by square wave voltammetry. For both polymers, the asymmetric membranes had higher cumulative percentage of drug released as compared to symmetric membranes. Asymmetric membranes diacetate reached about 80% release and that release was 30% to symmetric membranes. In the preparation of the microparticles were taken formulations acetate/solvent/naproxen acetate/ solvent/pore forming agent/naproxen. As solvents were used as dichloromethane for dioxane triacetate and diacetate for commercial as pore formers were inserted in formulations polyethylene glycol and water. Systems were prepared with different concentrations of naproxen in the ratio w/w acetate:drug 10:1, 2:1 and 1:1. The thermal analysis showed that the improved composition of the system polymer/drug was 10:1 w/w, since the drug does not appear melting peaks showing that the drug is molecularly dispersed in the polymer matrix. The kinetic model of drug release is broadcast solution. The particles produced with triacetate showed a release exceeding drug the particle produced commercially diacetate, where particles produced diacetate had a mean release of 2%, while the particles produced with modified triaceato reached about 25% release, featuring differences the interaction between the transparencies and the drug as well as increased stiffness of the particles produced with commercial diacetate. Modifications to polietilenogilicol and water in the particles with triacetate increased the release of naproxen, the release of the modified particles became 13% more than the release of the non-modified particles. The results show that the morphological changes in the controlled release systems are effective considering the increase in the percentage of drug release.

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Eight membranes of commercial cellulose acetate were prepared incorporating various additives, which changed their physicochemical properties. The membranes were divided into two groups (I and II) and their properties were evaluated. The four membranes of group they were prepared by adding, at a concentration of 0.1% (m / m) of the lignins extracted from the macaúba endocarp (Acrocomia aculeata) after purification and chemical modification. These four membranes were classified as to their composition as: (A) no additives (pure acetate); (B) with the purified lignin; (C) with the carboxymethylated lignin and complexed with Na+ (CML-Na) and (D) with carboxymethylated lignin and complexed with Al3+ (CML-Al). The other four membranes of group II has the same composition of Group I, but with added glycerol at a concentration of 10% (m / m). All eight membranes were prepared using a standard technique of spreading (casting method), after the dissolution in acetone. The percentage of 10% glycerol in membrane composition was determined in a previous study where the membranes prepared by the same technique, with a variable composition glycerol were studied and characterized. In this preliminary study membranes at concentrations of 0, 2.5, 5.0, 10.0, 15.0 and 20.0% (w / w) glycerol with acetate were dissolved in two solvents: acetone and a mixture acetone / water (80/20, v / v). The membranes with 10% glycerol shown in both solvents an increase of mechanical properties. The glycerol, as well as having plasticizer properties, is produced in large scale by first generation biodiesel industry, which uses the reaction transestrificação oils and fats. Concurrent with these studies, composition of the macaúba wendocarp was determined as the content of lignin, cellulose and hemicellulose. The large amount of lignin present in the endocarp (40.5%) and after purification (59.8%) showed that this residue has great potential for use of lignin. The macaúba after extraction of oils used in pharmaceutical industries and biodiesel discards lot of this waste without proper use. The characterization of the materials were made for determining the properties: morphology, by Scanning Electron Microscopy, SEM, structural: X-Ray Diffraction-XDR, hydrophobicity and barrier properties (contact angle and permeability to water vapor), thermal and thermomechanical properties: Differential Scanning Calorimetry - DSC, Thermo Gravimetric Analysis - TGA and Dynamical Mechanical Analysis - DMTA.

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The geostatistical contributes to greater efficiency in the application of fertilizers and pesticides in coffee growing, achieving, with the aid of this technique, to work the specific need of soil attributes on the property. It also allows accurately describe spatial distribution of chemical properties and biological properties of the soil, as for example, nematodes. The objective of the study was to verify the spatial dependence and elaborate geostatistical models that provide the efficient use of lime, fertilizers, nematicides in coffee growing, in order to aid in the preservation of natural resources, thus contributing to sustainable coffee farming. We attempted to also relate to the population of nematodes in soil fertility levels. The experiment was performed in a coffee plantation in the municipality of Araguari-MG Mineiro Triangle region, the farm has 65 hectares of arabica coffee (Coffea arabica L.), using a mesh of one point per hectare, totaling 65 points. Were analyzed: pH, macronutrients, soil organic matter (SOM), micronutrients and nematode. In the results it was verified that the geostatistical models were appropriate to describe the chemical soil properties and plant parasitic nematodes except for SOM and manganese, which were described by classical statistics. In the study became clear that advantage for agriculture with the use of geostatistics in relation to conventional farming, both for economic purposes, and for the environment, because when you work on time can make a better management of natural resources, both at the time of application on the property and in a more conscious demand. Was not possible to relate the population of nematodes in soil fertility.

The anthropic actions after the Industrial Revolution began to consider the environment as a space supplier of natural resources to the Capital. It suppressed the native vegetation of different biomes, replacing the space for cities, industry, agriculture, pastures, causing air pollution, which directly impacted in the current context of climate change. In this sense, it was noticed that there was a lack of public records inventories, containing greenhouse gases from UFU. The purpose of the study was to identify the institutional planning indicators for stationary combustion, mobile combustion, fugitive emissions, agricultural activities, solid waste and wastewater, for Scope 1 and acquisition of electricity and thermal energy for Scope 2 using the tool intersectoral GRI. We chose the methodology GHG Protocol for being an internationally accepted standard. The main results were the emissions of equivalent CO2, proposing neutralization through the planting of native plants of the Cerrado Biome. The inventory can not only enable the implementation of measures for mitigation and compensation, as well as optimize public spending, contributing to the Environmental Agenda of Public Administration (A3P).

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The projects in the energy sector, related to transmission lines, are composed of cables and metal structures, although providing benefits, the installation and operation still have significant environmental impacts along its stretch of passage. In this context, the aim of this study is to identify areas of "soil exposed", which may be related to erosion processes, and "fragments of native vegetation" in the range of direct influence of power transmission lines through computational techniques and remote sensing data. Tests were lead on Orthophotos, using the Maximum Likelihood Classifiers and Neural Networks, as well as the Object-Oriented Segmentation, integrating the Orthophotos with Laser Scanner data. The results analyzed based on Commission errors (accuracy of the user), Omission (accuracy producer) and kappa index. According to Kappa index calculated, the results showed variations between moderate and excellent content, indicating significant results with regard to the methodology used. Referring to the Commission and Omission errors, disarray in the classification process took place between classes presenting pixels with similar digital values within the same scene, especially within the classes that have different types of vegetation. With respect to the environmental diagnosis found in the range of direct influence of the transmission line, the portion of the sample median, indicates a high rate of anthropogenic interference. The class "Campo Limpo" had greater prominence, especially in areas with agricultural activities. The areas directly affected need attention as their recovery. It is emphasized that the results, which are found, is the first effort of diagnosis and research, requiring occasional visits in loco to prepare the planning recovery goals.

In response to drought stress, it is common on Fabacea family s species to develop physical dormancy imposed by the impermeability of the tegument. In the present study, the aim was to correlate the seed s coloration resulting from the different stages of maturity with the permeability degree of the teguments, the water and the Albizia lebbeck seed s germination. Besides that, this project aimed to determine the harvesting stage of fruits that precedes the installment of the dormancy on the seeds. The soaking and germination of freshly harvested seed s samples colored pattern extremely green (EG), green (G), light brown (LB), greenish brown (GB) and dark brown (DB) , stored for 60 days, was assessed. After 53 days of soaking there were elaborated and analyzed curves of water intake with individual weighting and sequential of 10 seeds for each coloration pattern. The germination experiments were conducted on a BOD greenhouse incubator and organized in 5 repetitions of 20 seeds for each coloration. The seeds were laid over blotting paper leafs on seed boxes conditioned to the temperature of 25º±1ºC with a 12 hour photoperiod. Daily scores of the germinated seeds were kept until the 32nd day. After that period the scores were kept every 72 hours, until 77 days were completed. The germination criteria adopted was the emission of the primary root with the geotropic curvature. The experiments results show that on the transmition of the EG pattern seeds to the DB pattern seeds there was a high reduction on the water content, from 57,3 % to 14,09%, respectively. The EG and G lots showed high permeability to water and in the process to the brown coloration this permeability was highly reduced with 70% of the DB seeds not soaking. For freshly picked EG and G the germination was high, 95% and 94%, respectively, reflecting the tegument high permeability. On the intermediate and final phases of patterns LB, GB and DB maturation, they showed a fall on the percentages of germination, being this respectively, 72%, 76% and 32%, and also a high mortality of seeds, 23%, 21% and 37%. When stored for 60 days, the EG seed s germination quality was not affected by the dehydration, keeping a high percentage (99%). G, LG and GB showed a fall on the germination capacity when stored, 68%, 45% and 58%, respectively, and the germination response of DB seeds was low on both tests, 32% and 33%. Albizia lebbeck seeds with a high water content (36,4% and 57,3%) and green coloration, don t show any restrictions to soaking and those harvested on the DB stage, with reduced water content (14,09%) have a high level of impermeability. EG seeds extracted from green fruits don t have physical dormancy and when stored for up to 60 days the dehydration doesn t impose dormancy. The seeds become dormant with the dehydration advance until levels near 11% of humidity are reached. The seeds extracted from green and slightly yellow fruits, have a higher germination capacity than those extracted from yellow fruits.

O presente trabalho tem como objetivo fazer uma representação dos “erros” produzidos pelos aprendizes de espanhol do Curso de Letras/Habilitação em Espanhol da Universidade Federal de Uberlândia. Para esse fim, foi compilado um corpus linguístico a partir de produções orais e escritas dos alunos do segundo, quarto, sexto e oitavo período. Os principais temas e autores que deram sustento teórico ao nosso estudo, quanto às análises descritivas, foram: Interlíngua (CORDER, 1967; SELINKER, 1972; BARALO, 1999, 2004; DURÃO, 2007), Linguística Contrastiva (SÖHRMAN, 2007), Modelo para Análise de Erros (DURÃO, 2004; ANDRADE, 2011; SANTOS GARGALLO, 2004), dentre os principais. Cabe destacar que adotamos uma perspectiva de análise de base empírica, apoiados nos subsídios que propicia a Linguística de Corpus (BERBER SARDINHA, 2004). Outro componente importante nessa dissertação foi a metodologia. Ela está detalhada passo a passo desde o levantamento e leitura do referencial teórico, até a finalização da escrita do trabalho. Presentando-se, dessa maneira, como um futuro referencial para pesquisas que se baseiam na utilização de LC como abordagem metodológica e na análise de erros de aprendizes. As análises desenvolvidas no decorrer desse trabalho, compreenderam primeiramente o dimensionamento dos corpora utilizados, seguido de listas das palavras mais recorrentes, análises quantitativas e qualitativas, as quais constituíram um mapeamento dos “erros”, outorgando, desta maneira, um valor potencial ao se tratar de um estudo que poderá ser utilizado como referente para uma eventual elaboração de material didático, pensado especialmente para as aulas de espanhol ofertadas no Curso de Letras/Habilitação em Espanhol da Universidade Federal de Uberlândia.

As mudanças no mundo do trabalho a partir da reestruturação produtiva levaram as instituições de ensino profissionalizante a reformularem suas propostas pedagógicas e a ofertarem um ensino voltado para as exigências do mercado de trabalho. Por isso esta pesquisa teve como objetivo analisar a educação profissional ofertada pelo SENAC Montes Claros/MG considerando a formação por competências em 2015. Foi realizada uma pesquisa documental em documentos do SENAC e aplicado um questionário aberto a cinco docentes de cursos técnicos do SENAC Montes Claros/ MG. As informações foram categorizadas e analisadas a partir de uma análise interpretativa. Além disso, aplicou-se um questionário estruturado de múltipla escolha a 164 alunos de cursos técnicos da mesma instituição. Os dados foram tabulados e os gráficos gerados a partir da estatística descritiva. Os documentos analisados mostram a adoção do modelo de competências pela instituição em estudo na formação profissional de nível técnico. Quanto ao desenvolvimento de competências em sala de aula, os docentes têm trabalhado com situações ligadas ao dia a dia das empresas abandonando a abordagem tradicional de ensino. Quando perguntados sobre a utilização do modelo de competências no cotidiano, os professores que disseram que ele está presente não conseguiram expressar como isso é feito e os que foram contrários a essa ideia responderam que o ensino ainda está preso à mensuração e a treinamentos que não enfatizam como deve ser a prática docente. Os alunos do curso técnico do SENAC Montes Claros/ MG constituem um público jovem, de baixa renda e pertencentes ou egressos de escolas públicas. Concluímos com essa pesquisa que os docentes procuram aplicar o modelo de competências em sua prática e seguem o que é proposto pelos documentos institucionais do SENAC Montes Claros/MG mesmo encontrando algumas dificuldades para isso. Quanto aos alunos concluímos que eles trazem consigo o conceito de empregabilidade uma vez que acreditam que a capacitação profissional deles garantirá um emprego. Também constatamos traços da dualidade estrutural do ensino, uma vez que são os alunos de baixa renda, que querem primeiro conseguir um emprego para depois continuar os estudos a maioria dos matriculados nos cursos técnicos. Por fim, comprovamos também a tradição e a força que o SENAC Montes Claros/ MG tem perante seus alunos.

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Diversos são os estudos sobre crenças na Linguística Aplicada desde meados de 1970 (BARCELOS, 2004), em especial crenças sobre ensino-aprendizagem de Línguas Estrangeiras (LE). A pesquisa sobre crenças e experiências de professores de LI, participantes do Programa Institucional de Bolsas de Incentivo à Docência (Pibid) e, portanto inseridos em escolas públicas (EP) de ensino básico tem relevância, uma vez que o (re)conhecimento dessas crenças relacionadas às suas experiências de ensino e aprendizagem de LI possibilita que os pibidianos reflitam sobre os aspectos que envolvem sua prática docente e seu papel enquanto professores. O intuito do presente trabalho é investigar a interação de crenças e experiências relativas ao ensino e à aprendizagem de língua inglesa (LI) de professores participantes do Pibid de LI na Universidade Federal de Uberlândia (UFU), no ano de 2013. Pretende-se identificar as crenças e experiências sobre ensino-aprendizagem que as professoras em formação inicial (PI), a professora formadora (PF) e as professoras supervisoras (PS) do programa apresentam e como suas crenças e experiências se influenciam e podem ou não ser ressignificadas. Esta é uma pesquisa de mestrado, de natureza qualitativa-interpretativista, em que analisei um relato de experiência de cada PI, uma entrevista da PF e das PSs e duas reuniões – a primeira entre a PF e os PIs, e a segunda com todos os participantes. Então, levantei crenças e experiências sobre ensino e aprendizagem de LI presentes em seu dizer e analisei trechos de suas falas que evidenciaram a interação com os outros participantes e a influência dessa interação para a formação, confirmação, desmistificação e ressignificação de suas crenças. Os resultados trazem elementos que podem fomentar a constante reflexão dos professores formadores, em formação continuada e em formação inicial acerca dos aspectos que envolvem as experiências docentes na EP.

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Esta tese é uma escrita em (d)enunciação, pois desvela as experiências de linguagem de indivíduos que, ao ocuparem, no espaço sócio-escolar, o lugar social de professor e de aluno, por alguma razão, sentem-se velados por uma demanda que os impede de ensinar e de aprender a escrita – e, até mesmo, a própria escrita. Para isso, problematizamos questões concernentes à enunciação benvenistiana e ao processo de ensino e de aprendizagem de escrita em Língua Portuguesa a partir da tríade relação professor – ensino de escrita/saber – aluno, aproximando o campo teórico enunciativo, fundamento deste trabalho, e o didático-pedagógico. Apostamos na hipótese de trabalho que se baseia na posição de que o afrouxamento dessa relação triádica repercute seus efeitos no processo de intervenção-inter(fere(ê))ncia, de tal modo que esse processo não fere o aluno, deixando uma cicatriz que permaneça produzindo ali efeitos produtivos sobre sua escrita. Em decorrência dessa pressuposição, evidenciamos duas constatações de chancelar a possibilidade de saída(s) que permite(m) considerar que o ensino de escrita em Língua Portuguesa é o espaço para a (cri)atividade escrita, de maneira que se instaura como uma condição sine qua non para a assunção do aluno a uma escrita institucionalizada e subjetiva. A primeira constatação é a de que há implicações para o processo de ensino e de aprendizagem de escrita se considerarmos o gênero como modelo, conforme as diretrizes e orientações dos documentos oficiais. A segunda constatação, em decorrência da primeira, admitimos que o gênero é, ao mesmo tempo, um modelo e uma transgressão, tomá-lo como (a)mostra abre espaço para a (cri)atividade escrita que ―é uma transposição da linguagem interior‖ (BENVENISTE, 2014 [1968-1969], p.132), de modo a torná-la inteligível e ressaltar aquilo que é da ordem de um modelo (o iterativo) e de uma transgressão (o inventivo). A partir dessas constatações, para os procedimentos analíticos, constituímos os materiais de análise que compõem o corpus heterogêneo desta pesquisa, de acordo com as seguintes ações procedimentais: gravação em áudio das aulas; gravação em áudio das entrevistas com os professores e com os alunos; e a constituição de um acervo de produção escrita dos alunos. Desse conjunto de materiais, analisamos a (a)(tu)ação, em mo(vi)mentos enunciativos, dos envolvidos na relação triádica professor – ensino de escrita/saber – aluno, as histórias das enunciações, das experiências de linguagem. Além disso, analisamos o discurso no qual se inscreve o dizer do professor em relação ao modo como 'constrói' sua aula em função do saber a ser ensinado e de sua relação com esse saber, a fim de, em outro mo(vi)mento de análise, circunscrever suas implicações na escrita dos alunos. As análises (re)afirmaram que, ao afrouxamento do laço na relação triádica, abrem-se espaços para que os alunos permaneçam à deriva, em vão, impossibilitando-lhes, epilinguisticamente, de realizar um trabalho elaboral sobre a própria escrita. Em razão disso, a instituição escolar vem perdendo sua especificidade, como lugar de ensino, lugar de ensinar o aluno a ler e a escrever e abrindo espaço, cada vez maior, para o treino. Nesse sentido, consideramos que o efeito desse afrouxamento repercute um sintoma que se manifesta em queixa, em denúncia. Logo, com base nessas (d)enunciações, apresentamos o Esboço em preliminares de uma pro(a)posta de/para intervenção- inter(fere(ê))ncia no trabalho do ensino de escrita e,assim, buscamos oferecer ao ensino, ao professor, um conjunto de conhecimentos que lhe possibilite a reflexão e saídas.

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