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Avaliação da atividade fotocatalítica do óxido de cobre imobilizado em suporte magnético nanoestruturado
(Universidade Federal de São Carlos, 2015-07-31) Santos, Lílian Cruz; Paris, Elaine Cristina; https://lattes.cnpq.br/8475640212486290; https://lattes.cnpq.br/8780294623715549
Contamination by dyes is one of the main problems related to water and environment pollution. In recent years, the search for new alternatives for the appropriate treatment of organic wastewater compounds has intensified. This study aims to evaluate the photocatalytic activity of copper oxide nanoparticles II (CuO), as well as obtaining nanostructured magnetic and porous media for the immobilization thereof. The CuO is a p-type semiconductor that acts as a sink photogenerated electrons. In this work, the CuO has been obtained by coprecipitation,hydro and solvothermal methods, with particles sizes of approximately 15 nm, 1 μm and 1 μm respectively. The materials' photocatalytic activity have been evaluated under excitation in the visible and ultraviolet regions. In all the cases, CuO proved to be efficient for the Rhodamine B color removal in the presence of hydrogen peroxide under visible light for 1 hour; reaching over 90% of color removal effectiveness. The main factor that makes impracticable the use of photocatalysts for water treatment on a large scale is the difficulty on recovering the active material. Thus, in this study, a magnetic scaffold composed of magnetite:hydroxyapatite has been developed. Magnetite provided magnetic activity to the medium, while the hydroxyapatite was used to provide sufficient porosity to the material in order to immobilize the CuO nanoparticles. In addition, the magnetite was protected of the oxidation process and consequent magnetic activity loss. The magnetite and hydroxyapatite have been obtained by chemical coprecipitation, presenting average particles sizes of 50 and 15 nm, respectively. The magnetite:hydroxyapatite magnetic scaffold presented the desired homogeneous chemical composition, indicating a successful synthesis. The magnetic photocatalyst has been obtained by CuO impregnation on the magnetic scaffold using an ultrasonic probe-type. The photocatalyst immobilized on magnetic scaffold proved to be efficient on the color removal of Rhodamine B dye, reaching the same efficacy than pure CuO. The immobilized photocatalyst remained efficient on color removal when re-used.
Solidificação rápida e conformação por spray de ligas ferrosas amorfizáveis a partir de ferros fundidos com adição de boro e nióbio
(Universidade Federal de São Carlos, 2015-07-31) Lucena, Felipe Amélio de; Afonso, Conrado Ramos Moreira; https://lattes.cnpq.br/2176215981291453; https://lattes.cnpq.br/0474221317198742
The amorphizable ferrous alloys and/or nanocrystalline ones have high hardness properties and wear resistance which are important technologically. Rapid solidification process with cooling rate between 102 - 106 K/s leads to high hardness properties and wear resistance. The objective of this work is the study and the characterization of microstructure and hardness of white cast iron and nodular gray by rapid solidification, exploring techniques that impose different cooling rates, with different additions of Boron and addition or not of Niobium. The alloys were processed by Discovery® Plasma and melt-spinning, namely: (Fe65Cr17Mo2C14Si2)100-xBx (Fe65Cr17Mo2C14Si2)88B8Nb4 and (Fe75Nb6C10Si4)100-xBx (at%). The characterization was made by X-ray diffraction (XRD), differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Vickers microhardness (HV). The (Fe65Cr17Mo2C14Si2)88B8Nb4 (at%) alloy was selected to spray forming and laser cladding processes obtaining deposit and overspray powders into different particle size from 20 μm and more than 180 μm. The alloys were copper mold cast resulting in plate samples with thickness of 1.0 and 2.0 mm. The cast iron plate microhardness, without Boron and Niobium, showed around 650 HV and about 1400 HV after the addition of 12 at% of Boron. The (Fe65Cr17Mo2C14Si2)88B8Nb4 (at%) alloy has nanocrystalline microstructure after spray forming in the deposit and overspray powders and Vickers microhardness value of about 1040 HV in the deposit. For these alloys it was required high cooling rates of about 106 K/s to obtain amorphous phase by melt-spinning process. The laser cladding process used overspray powders to produce coatings with microhardness up to around 1300 HV. It was possible using power 200 W, in slower scanning travel speeds (6.7 or 10.0 mm/s). The laser cladding process presented good perspectives of application in order to produce wear abrasion and corrosion resistant coatings.
Revestimento nanoestruturado de cera de carnaúba na manutenção da qualidade pós-colheita de tomates
(Universidade Federal de São Carlos, 2015-07-31) Miranda, Marcela; Corrêa, Daniel Souza; https://lattes.cnpq.br/0461451015026948; Ferreira, Marcos David; https://lattes.cnpq.br/6652079760634274; https://lattes.cnpq.br/7264328133239438
Tomato is one of the most popular and consumed vegetable. However it is highly perishable because of its high water content. Post-harvest technologies of fruits and vegetables try to increase the shelf life of fruits, to keep quality and to reduce quantitative and qualitative losses between harvest and consumption. One of these technologies is based on the use of coatings on fruits and vegetables, because they are effective in reducing water loss and maintaining the quality of fresh products. This study aimed to synthesize and compare conventional emulsion and nanoemulsion of carnauba wax, as well as to evaluate the influence of different concentrations of these coatings on tomatoes (Solanum lycopersicum) during storage. Therefore, emulsions with different particle sizes were synthesized and characterized by particle size measurements (hydrodynamic diameter); zeta potential (colloidal stability); polydispersity index; scanning electron microscopy images; contact angle and stability in different environments. In sequence, the emulsions were applied on 'Débora' and 'Pizzadoro' cultivar tomatoes to evaluate the effect of these coatings on the physical and chemical quality and the internal atmosphere of the fruits. For that purpose, the following experiments were performed: (I) 'Débora' cv Tomatoes were coated with conventional emulsion and nanoemulsion at concentrations 9% and 18% and stored at 23 °C ± 1 (80% RH) for 16 days. Assessments of physical chemical and gases analyses (ethylene, CO2 and O2) were carried out. (II) 'Pizzadoro' cv Tomatoes were coated with conventional emulsion and nanoemulsion at concentrations of 9% and 18% and stored at 23 °C ± 1 (80% RH) for 13 days and the same quality analyses were carried out. (III) Sensory analysis in 'Deborah' cv tomatoes coated with conventional emulsion and carnauba wax nanoemulsion at concentrations 9% and 18% and stored at 23 ° C ± 1 (80% RH) for 10 days, were evaluated for the visual appearance, purchase intent and ordering by preference. Nanoemulsions showed smaller particle size and polydispersivity compared to conventional emulsion. In post-harvest tests, fruits coated with emulsions showed lower weight loss rate than control fruits. 'Pizzadoro' cv tomatoes coated with both emulsions appeared to be clearer and less red at the end of storage than the control sample. Nanoemulsion carnauba wax did not change the barrier property of the coating responsible for controlling water permeation, and presented performance similar to conventional emulsion. The nanoemulsion showed more acceptance, purchase intent and preference by tasters in the sensory test, probably due to the high brightness attained by this coating.
Perfil da Produção Brasileira sobre História da Química em Periódicos e Congressos: subsídios para a formação docente e sala de aula
(Universidade Federal de São Carlos, 2015-07-31) Castro, Flávia Pierrotti de; Marques, Rosebelly Nunes; https://lattes.cnpq.br/7921735904003583; https://lattes.cnpq.br/8143571675274459
The History and Philosophy of Science (HFS) is recognized by many authors as contextualization instrument of scientific knowledge in Science Education, as well as teacher training. The HFC can provide the teacher, subsidies to better understand the conceptual difficulties of students, enabling a better understanding of the role of science in the development of societies. The practice teacher based on the epistemological reflections creates a better educational performance, more approaching the images of science developed in the classroom with the true nature of science, making the act of teaching a constant research process. Considering this importance, this research has the main objective to define the profile of the Brazilian intellectual production on the History of Chemistry and Science through systematic review methodology (SR), to contribute to the initial and continuing teacher training. The SR consists of rigorous and systematic overview of all research related to the specific issue through the development of structured protocol with their descriptors, inclusion and exclusion criteria and the analysis of the recovered texts. For this research, we used twelve (12) descriptors in Google Scholar database, with the inclusion criteria, texts published between 1993-2013, in Portuguese (Brazil), to bring relevant discussions relating the concepts with HFS chemicals for the formation/maturation of the knowledge of teachers, so that they can improve their teaching practice, as well as texts that present didactic sequences that contextualize the chemical knowledge to the History of Chemistry and/or Science. From crossing the descriptors, it was generated a universe of 1599 texts with 92 selected for the selective reading. In analysis of the recovered texts, 63 publications are related to the epistemological discussions, with the largest production (68,3%) in the 2006-2013 period, in Química Nova and Química Nova na Escola (41,2%), most approach has the Chemical Elements content (17,46%) and historical period being further discussion the twentieth century (23,8%). For texts related to the methodological proposal, 29 publications were analyzed, with the largest production (75,9%) in the period 2011-2013, in the proceedings of conferences (62%) highlighted the XVI Encontro Nacional de Química (24,1%), the higher was the content of approach weight Laws (17.2%) and historical period being further discussion the eighteenth century (27,6%) correlating directly with the chemical content with a higher approach. The survey sought to outline the profile of the Brazilian intellectual production over the last twenty years, present in journals and conferences because studies recovered relating to HFS with chemical concepts can be extremely relevant to the formation/maturation of teachers, so that they they can improve their teaching practice and incorporate this knowledge in their teaching sequences.
Aplicação de métodos quimiométricos de calibração e resolução multivariada de curvas em espectroscopia Raman para Análise qualitativa e quantitativa de polimorfismo em carbamazepina, clopidogrel e ezetimiba
(Universidade Federal de São Carlos, 2015-07-31) Farias, Marco Antonio dos Santos; Carneiro, Renato Lajarim; https://lattes.cnpq.br/8065852319463976; https://lattes.cnpq.br/2589951282251863
In this work were used chemometric tools like PLS, iPLS to perform multivariate calibration of ternary and binary mixtures of polymorphs of carbamazepine, ezetimibe and Clopidogrel. Initially were synthesized two polymorphs of carbamazepine and two polymorphs of clopidogrel from its respective commercial polymorphs, totaling three polymorphs for each of these drugs. For carbamazepine were synthesized the dihydrate polymorphs (CBZ DH) and polymorph I (CBZ I) from the Polymorph III (CBZ III), which were characterized by DSC and XRD, and Raman spectroscopy. Inittialy an iPLS model was built with the polymorphs. The samples were prepared according to a ternary mixture, totaling 10 samples for a set of calibration and a further 5 to a set of validation. At each sample was collected 10 Raman spectra at different points, subsequently an arithmetic average of the 10 spectra was calculated, resulting in an average spectrum with which is built the model calibration and validation presenting prediction error: (CBZ I) 6 2 mg; (CBZ III) 6.8 mg; (CBZ DH) 11.6 mg. In a second step the same procedure was conducted, but samples (300 mg) were in the presence of its excipients (microcrystalline cellulose, sodium croscarmellose, magnesium stearate and colloidal silicon dioxide). The samples were prepared by adding (250 mg), carbamazepine (50 mg), prediction errors were: (CBZ I) 4.8 mg; (CBZ III) 3.0 mg; (CBZ DH) 0.7 mg. For bisulfate Clopidogrel were synthesized polymorphs II (CBS II) and amorphous (amorphous CBS) from polymorph I (CBS I, commercial), the iPLS calibration model was constructed as done for carbamazepine, however were used mid-infrared and Raman spectroscopy and the samples were not prepared in the presence of its excipients. Prediction errors for the model with Raman spectroscopy was: (CBS I) 3.2 mg; (CBS II) 5.0 mg; (Amorphous CBS) 6.1 mg and mid-infrared spectroscopy was: (CBS I) 4.8 mg; (CBS II) 7.4 mg; (Amorphous CBS) 6.9 mg. For ezetimibe was synthesized the hydrate (EZT-H) from the commercial polymorph (EZT-An) and held a binary mixture of the two polymorphs, with the concentration of each polymorphs ranging 10% by weight in each sample, since in the presence of its excipients. Each sample weight 100 mg, with 10 mg of ezetimibe and 90 mg of excipients (croscarmellose sodium, lactose monohydrate, povidone and sodium lauryl sulphate), the same method was applied for the preparation of the samples validation set. The calibration model was built by iPLS with the following prediction errors: (EZT-An) 0.7 mg; (EZT-H) 0.6 mg. A new sample was prepared only with EZT-An and the excipients which was vacuum packed in a polyethylene container, carried out a monitoring for 24 hours where it was seen that in this period the hydration of Ezetmiba was already 72% due to the moisture of the excipients.