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Desenvolvimento de sensores eletroquímicos utilizando nanomateriais para a determinação de espécies de interesse farmacêutico e ambiental
(Universidade Federal de São Carlos, 2014-07-25) Figueiredo Filho, Luiz Carlos Soares de; Fatibello Filho, Orlando; https://lattes.cnpq.br/9859737944357808; https://lattes.cnpq.br/3210207943263219
In this work the development of new sensors using nanomaterials is decribed. Glassy carbon electrode modified with gold nanoparticles and functionalized multi-walled carbon nanotubes within a dihexadecyl phosphate film was fabricated and applied to determine diquat in natural water samples by square wave voltammetry (SWV). The analytical curve was linear in the diquat concentration range from 3.1 × 10−8 to 3.0 × 10−6 mol L−1 with a limit of detection (3 blank/slope of analytical curve) of 1.4 × 10−8 mol L−1. The performance of this electrode was compared with a commercially screen printed electrode from dropsens. The determination of linuron in natural water samples and commercial products was successfully performed using the boron doped diamond with good linear range, repeatability, sensitivity and stability. Moreover, the electrode had the analytical characteristics compared with the same electrode modified with platinum nanoparticles. A glassy carbon electrode with dihexadecyl phosphate film containing platinum nanoparticles was developed to determine linuron and carbendazim in natural waters, orange juice and commercial products by pulse diferential voltammetry (DPV) and square wave voltammetry (SWV) techniques. The detection limits obtained were 6.1 × 10−10 and 1.5 × 10−9 mol L−1 for linuron and carbendazim using SWV, respectively, and the obtained results were in agreement at a 95% confidence level with those results obtained using a high performance liquid chromatography method. Glassy carbon electrode modified with nickel oxide nanoparticles and functionalized multi-walled carbon nanotubes within a dihexadecyl phosphate film was fabricated and applied to the simultaneous determination of dopamine and epinephrine by DPV. The analytical curve obtained shown a linear range from 7.0 × 10−8 to 4.8 × 10−6 and 3.0 × 10−7 to 9.5 × 10−6 mol L−1 for dopamine and epinephrine, respectively. Both analytes were determined in three different synthetic samples of biological fluids (lung fluid, cerebrospinal fluid and human serum) with an acceptable relative standard deviation for the addition and recovery test. Graphene and graphite paste electrodes were also investigated in this thesis. Initially, graphene and graphite were characterized morphologically (RAMAN and XPS), as the obtained pastes. Moreover, the proposed paste electrodes were characterized electrochemically through well-known electrochemical probes as hexacyanoferrate (II) potassium, hexamine ruthenium chloride (III) and hexacloroiridiate (III) sodium. After this study, analytical curves for ascorbic and uric acids were built. It was observed that no significant analytical advantages were obtained when graphite was replaced by graphene in the pastes. The electrochemical of graphene and reticulated vitreous carbon three-dimensional electrodes was first explored in this work. It was observed that due to the hydrophobic nature of the graphene three-dimensional electrode, its application is not favorable in aqueous solutions. Furthermore, this material showed good electrochemical characteristics using ionic liquids as supporting electrolyte, better HET and higher current to electrochemical probes hexacyanoferrate (II) potassium, hexamine ruthenium (III) chloride, ferrocene and N,N,N',N'-tetramethyl-p-phenylenediamine compared with the three-dimensional reticulated vitreous carbon electrode.
Avaliação das características mecânicas de compósitos de cimento Portland reforçados com fibras de polipropileno aditivadas com modificadores de superfície
(Universidade Federal de São Carlos, 2014-07-25) Esposto, Ricardo Francisco; Morelli, Márcio Raymundo; https://lattes.cnpq.br/0172837599844991; https://lattes.cnpq.br/7978232406039488
The application of polymeric fibers as reinforcement in cement based composites is a highly developed technology in various applications in construction. The use of polypropylene fibers have been widely used, but with some technological limitations, mainly because of them present low interaction with the cement matrix when compared with other polymeric fibers. For this work, we sought to evaluate polypropylene fibers doped with surface modifiers, with emphasis on mechanical and microstructural characteristics of composites. Different amounts of fiber with and without surface modifying additives in matrices of Portland cement mortar after 35 days of age were evaluated. The physic-chemical interactions of the fiber with the matrix were evaluated by pullout tests and through reviews of scanning electron microscopy. Some specimens were subjected to accelerated aging tests and these samples were analyzed by electron microscopy to observe the behavior of the interaction of the fiber with the additive, but also for assessing the behavior of the fiber with the matrix after exposure to aging. The results obtained by the mechanical resistance measures uniaxial compression and scanning electron microscopy showed that a mechanical reinforcement occurs independent of incorporation of additives in fiber to additions of 1.2 kg/m3. On the other hand, the surface-treated fiber exhibited higher degree of adhesion to the matrix.
Uso de ferramentas tecnológicas no ensino de física para o ensino médio: modelagem matemática a partir do software Modellus
(Universidade Federal de São Carlos, 2014-07-25) Barsotti, Daniela Cristina; Garcia, Ducinei; https://lattes.cnpq.br/5236758856687873; https://lattes.cnpq.br/8857372188018044
This work presents a case study on the teaching and learning of Physics concepts using mathematical modeling and technological tools, with software Modellus 4.01 as the main resource. Modellus 4.01 was selected due to its ability to provide a user-friendly platform for developing animated simulations from user-defined mathematical models, in addition to windows that can display graphs and tables dynamically. The main objective of this work is to propose an answer to the question: Is it worthwhile to use a computational tool with mathematical modeling to enhance student s learning results in secondary education? After all, much has been presumed about using computers to improve Brazil s overall performance in basic education, but there are very few formal studies on their actual utilization, especially at a complex level like the simulations from mathematical models developed by the students themselves. A sequence of activities for the modeling of kinematics concepts is proposed and discussed. While considering the steps of such sequence and their application with 9th-grade students in computer-equipped facilities, this work also presents and analyses the results of a diagnostic assessment of students theoretical knowledge; their acceptance of the Modellus software; the URM and UVRM simulations they developed; and the concepts they gathered from the work with modeling and computational tools. It is therefore possible to reflect upon the effectiveness of this methodology towards a more meaningful learning of the concepts involved, as well as the difficulties arising from the use of technological tools in the school environment. The outcomes from sharing the products and investigations of this work with other teachers, whether in specific projects like the Observatório da Educação (The Observatory of Education - Obeduc Capes-UFSCar) or in academic networking events are also discussed. In general terms, results show that the application of activities in the suggested order may be an important support to the motivation of students and to a meaningful learning of the Physics contents pertaining to the 9th grade program.
Nano-microencapsulados de extrato de Azadirachta indica usando ligninas do bagaço de cana-de-açúcar: estabilidade e eficácia contra insetos pragas
(Universidade Federal de São Carlos, 2014-07-25) Costa, Eveline Soares; Forim, Moacir Rossi; https://lattes.cnpq.br/1234565160573730; https://lattes.cnpq.br/9126084206992314
The present work aimed the development of a model bioinsecticide for pest insect control using microencapsulated botanical extracts of Azadirachta indica (neem), and natural polymer of lignins, witch were extracted from sugarcane bagasse. Several different extraction methods and chemical modifications were carried out on lignin in order to evaluate yield, cost, environmental advantages and biological efficacy. Among the proposed chemical modifications the main reactions were oxidation and acetylation. Techniques used for biopolymer characterization were FITR, 1H NMR, MALDI-TOF and SEM. Chemometric tools on NMR analyses aided on lignin differentiation according to their groups: oxidized, acetylated and naturals. Lignins were used in microencapsulation processes of extracts and fractions of the natural insecticide, A. indica L. Juss, by using Spray-Drying methods. The obtained products were subjected to thermal and photochemical degradation assays. The formulation promoted stability gains of approximately 40% for the formulated botanical extract. Use of commercial thermal and photochemical protectors were also investigated where it was observed that lignin was more efficient than traditional commercial photostabilizers protectors, showing that there is no need for adding synthetic protectors on microencapsulation process, and consequently, they are not needed on the final product. Microencapsulation was done through process known as Nanoemulsion/Solvent Displacement developed by the workgroup. In this process, botanical material was firstly nanoemulsioned, coated by a biopolymeric film in order to promote nanocapsules, and dried using Spray-Dryer generating micrometric clusters. All formulated material was subjected to biological assays to Spodoptera frugiperda, Diabrotica speciosa, Diatraea saccharalis e Anticarsia gemmatalis. Data obtained on biological testes shows that formulations that were prepared with neem and lignin were as active as non-formulated botanical extract on pest insects.
Conteúdos digitais para o tema ondulatória na proposta curricular do Estado de São Paulo
(Universidade Federal de São Carlos, 2014-07-25) Magalhães, Arthur Alexandre; Arantes, Alessandra Riposati; https://lattes.cnpq.br/6742903299047989; https://lattes.cnpq.br/4217678767890330
This work proposes digital content for the Waves theme which can be inserted into the curriculum of the State of São Paulo. Technologies are part of the daily lives of students, and can be used as motivational tools in the teaching-learning process. Digital content consists of learning objects, such as videos, audios and simulations, accompanied by activities that provide an active student participation in the teachinglearning process. Activities were inspired by research methodology and have different levels of freedom, i.e. varying degrees of teacher intervention. We conclude that the activities with greater student autonomy lead to a more meaningful concept learning. It is noteworthy that, in addition to the positive result, this work has produced a considerable change in my teaching practice as I started to develop activities with investigative approach, in which the student carries out the process of knowledge construction.