Repositório RCAAP

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The physical, chemical and biological characteristics of water, which together allow the evaluation of its quality, remain associated with a series of processes that occur in the water body and its drainage basin. The consumption of water with quality specified in the legislation is of fundamental importance for health promotion and prevention of risks related to water contamination due to the adverse effects of human activities. For each preponderant use of water, there is a required quality, according to the standardization proposal by legislation. The standard of water quality and effluent is required based on laboratory analysis of essentially physicalchemical parameters. However, these parameters are generally insufficient, because it is impossible to determine all the chemical components in a water sample to evaluate its potential toxic effects on the biota. In evaluating the impact of certain substances on aquatic life it is necessary to use living organisms as bioindicators. Thus, this study aimed to promote an integrated evaluation of water quality of the Uberabinha River, in the City of Uberlândia - Minas Gerais - Brazil, which had not been done heretofore. The research was based on the chemical characterization of sediments, because they are substrates for a wide variety of organisms, which feed higher trophic levels and the use of fish as bioindicators of genotoxicity. Four samples were taken in different seasons of the year: rainy, dry, very dry, transition between rainy and dry. Five evaluation points were established, where the water samples and sediments were collected to be forwarded for review and any necessary procedures. In defining these five sampling sites, we sought to identify areas that characterize the natural flow of water upstream and downstream of the city, and the areas where human interferences are significant. For the water samples the following parameters were evaluated: temperature, pH, odor, color, turbidity, hardness, fluoride, phosphate, chloride, nitrate, nitrite, ammonia, sulfates, sulfides, chlorine residuals, surfactants, dissolved oxygen, dissolved solids, COD, BOD, barium, coliforms and fecal coliforms. The Water Quality Index was calculated and compared with the values set out in legislation. For the sediment samples the following parameters were evaluated: fixed solids, volatile solids, aluminum, cadmium, calcium, lead, copper, chromium, iron, manganese, potassium, sodium, zinc, organic matter, total carbon, as well as the pH, density and particle size analysis. Values obtained for the concentrations of cadmium, lead, copper, chromium and zinc were compared with the values of Sediment Quality Guidelines - SQVG, national and international. The results obtained with tests performed on specimens of micronucleus Catfish, Rhamdia quelen, demonstrated the effect of contamination at the sampling points. Multivariate statistical analysis was used in the treatment of data, to correlate various contaminants and not only the addition of the toxicity values of the different components analyzed individually.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The present study describes the analytical performance of on-line preconcentration systems using modified silica prepared by sol-gel as sorbent in the extraction/speciation metals, employed flow injection analysis and detection by Flame Atomic Absorption Spectrometry (FAAS). Materials were characterized by FTIR, EDXRF, SEM, EDS, XRD, SBET and EPR. The experimental parameters were studied by multivariate analysis using factorial design, Doehlert design and desirability function. In Chapter I, it was employed a new adsorbent, containing manganese oxide particles dispersed in a silica matrix (SiO2/Mn3O4) to improve the detectability of FAAS for Cd2+ determination. The analytical features were obtained: linear responses in the range of 1.0-50.0 g L-1 (r = 0.9968), the detection (LOD) and quantification limits (LOQ) of 0.20 and 0.68 g L-1,respectively, preconcentration factor (PF) of 39.3, concentration efficiency (CE) of 19.7 min-1, consumption index (CI) of 0.51 mL, and analytical frequency (AF) of 20 h-1. The Chapter II, describes the analytical performance of the hybrid material (SiO2/Al2O3/TiO2) as an adsorbent for Cu2+ enrichment. LOD and LOQ of 0.46 and 1.43 μg L−1, respectively, and linear analytical curve from 5.0 up to 245.0 μg L-1 (r = 0.999), were achieved. Besides, the following parameters were calculated: PF of 49.05, CI of 18.9 min-1, IC of 0.26 mL and AF of 23 h-1. Finally, in Chapter III, the on-line preconcentration system using two minicolumns containing SiO2/Al2O3/TiO2 e SiO2/3-(2-aminoethylamino)propyltrimetho -xysilane (SiO2/AAPTS) was proposed for sequential preconcentration/speciation of Cr3+ and Cr6+ and determination by FAAS. The LOD and LOQ were 0.66 and 2.21 μg L-1 for Cr3+ with a linear analytical curve from 10.0-375 μg L-1 (r = 0.9981). PF, CI, CE and FA were 17.62, 1.13 ml, 6.2 min-1 and 21 measures h-1, respectively. For Cr6+ the LOD and LOQ were 0.27 and 0.93 μg L-1 with a linear analytical curve from 10.0 - 375 μg L-1 (r = 0.9993). The PF, CI, CE and FE were 32.98, 0.6 ml, 11.54 min-1 and 21 measures h-1, respectively. The accuracy of the preconcentration methods was checked using analysis of certified reference materials (CRM).

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Erythrocytes or red blood cells are single cells among mammalian cells. They contain no organelles and nucleus, containing hemoglobin inside, surrounded by a membrane. They are responsible for transporting oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs, which makes its integrity important for the proper functioning of the whole organism. One of the substances that may cause effects on erythrocyte membrane is ethanol, found in a wide variety of products. In this work, the interactions between ethanol, water and sodium chloride with membrane phospholipids was evaluated using experimental assays combined to molecular dynamics approach. The blood of two young rats was used to evaluate the effect of increasing concentrations of ethanol, 0-50% (v/v) on the osmotic fragility of the cells. In addition, a theoretical study involving molecular dynamics simulation was performed using the software package GROMACS, in which dipalmitoylphosphatidylcholine - DPPC was used as membrane model. GROMOS 53a6 force field was used in the computer simulations, considering a time of 60 ns for each system. The experimental results show that increasing ethanol concentration raises the lyse of the erythrocytes. However, for values higher or equal to 35% (v/v), the lysis is reduced. The theoretical data illustrated the affinity of ethanol by the membrane lipids, generating changes in the charge orientation along the bilayer, forming pores, changing the permeability and deforming the bilayer in high concentration of ethanol. It is noted, in this study, that the deleterious effect of ethanol on the erythrocyte membrane is non-dose dependent and that it acts, by interaction, with the structure of the lipid bilayer.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

This work describes the development of solid phase extraction methods for metal ions speciation with emphasis on chromium and arsenic, using Moringa oleifera seeds and their husks as bioadsorbents. Initially, characterization techniques including infrared spectroscopy, thermal analysis, scanning electron microscopy, energy dispersive spectroscopy and study of surface areas by theory adsorption multielement were used in physic chemical evaluation of husks and Moringa oleífera seeds. Subsequently, it is presented the development of flow system for extraction/preconcentration of Cr(III) and Cr(VI) species coupled to the spectrophotometry flame atomic absorption for determination of these species in food and environmental samples. The system is based on the selective retention of Cr(III) and Cr(VI) species in mini- columns filled with husks of the Moringa oleifera seeds. Chemical and flow variables were evaluated using the multivariate method. The retention of Cr(III) occurs in the approximately pH 7,0, and the Cr(VI) retention was approximately pH 1-2. The results of the optimized conditions, selected with the compromise between sensitivity and sample throughput were sample flow rate 4.5 mL min -1 , eluent flow rate of 4.0 mL min-1 ; eluent concentration of 0.01 mol L- 1 the HCl for Cr (III) desorption and 0.01 mol L-1 NaOH to Cr(VI) desorption. The detection limit was 1.9 mg L-1 for Cr (III) and 2.45 g L-1 for Cr (VI). The linear response range was from 5.73 to 1000 mg L- 1 for Cr ( III ) and 7.35 to 1000 mg L-1 for Cr ( VI ) . In order to validate the proposed method , it was applied to water and alcohol samples, as well as the analysis of standard certificate. The study carried out demonstrated the feasibility of using Moringa oleifera husks in flow systems for separation and pre- concentration of chromium species. At the end of the work presents the development of a method for selective extraction of arsenic inorganic species of and detection by Atomic Absorption Spectroscopy Graphite Furnace. The method is based on the selective retention of inorganic arsenic species using as the bioadsorbent Moringa oleifera seeds, the pH being variable to the separation process. At pH 7.0 this As (III )species is quantitatively retained by the seed while the adsorption of As( V) occurs to a lesser extent . The variables that affect the adsorption: mass and contact time were studied, having been found values of 1.0 g and 60 minutes as optimized values . The process of As (III) adsorption of the seeds was studied by starting the construction of adsorption isotherms. The method was applied to the speciation analysis of inorganic arsenic in water samples and evaluated the accuracy of the method based on the analysis of reference material. The values obtained showed high agreement with the actual values , demonstrating the efficiency of the proposed method.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Conselho Nacional de Desenvolvimento Científico e Tecnológico

This work has the purpose analyze the contributions of the Programa Institucional de Bolsa de Iniciação à Docência hereby called as (PIBID) for initial teacher training in Chemistry, identifying limitations and possibilities in teacher professional development, in twenty-one institutions of higher education, hereby called as (IES), the five Brazilian regions. The research involved 160 undergraduates, and at the time received student allowances on the Chemistry PIBID subprojects. They answered a questionnaire with discursive and multiple-choice questions. The questions intention was identifying the socioeconomic profile of grantees; understand their expectations about the Chemistry course, their professional perspectives and experiences in PIBID. To get a better understanding of the possibilities, limitations and contributions of the program, there were performed a survey of research papers, theses and dissertations related to PIBID. Due to the youthfulness of this program, many of these investigations have served as reference for the analysis of data obtained in the questionnaire. They were organized into two parts: the first part purpose was drawing a socioeconomic profile of grantees and, the second one was verifying that the PIBID goal has been achieved. Therefore, the second part was organized in the following categories: i) teaching encouraging; ii) enhancement of the teaching profession; iii) integration university-school; iv) creation/contribution in practices of innovative character; v) role of the supervisor and, vi) coordination theory and practice. Although these categories were based on the program goals, it is understood that they can also be achieved in other ways, such as experiences before graduation as well as pedagogical and specific subjects of the course and the school internship experience. One can understand also that the university-school interaction enables the future support teachers better grounded in the teaching practice and, from there, an improvement from the perspective of their training. Therefore, we sought to determine whether the participation of undergraduates in PIBID highlights fragilities and / or potential in initial training courses in Chemistry. Some considerations are taken about the PIBID and their possible contributions to the Chemistry future teachers formative processes in several institutions. Based on the identification of these contributions was possible verifying how much PIBID has enabled learning about teaching; and infer about their possible impacts in several subprojects both as for Basic Education school as for the future teachers of Chemistry learning.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais