Evaluation of different teaching methodologies by assessing the performance of dentistry students / Avaliação de diferentes metodologias de aprendizagem aferindo o desempenho de estudantes de odontologia

Objective: The aim of this study was to compare the performance of day- and evening-class students in the first semester test of Dental Materials in the School of Dentistry at São José dos Campos - UNESP, who were exposed to traditional lectures (TRAD) and Team-Based Learning (TBL). Material and Methods: The results of Dental Materials first semester test of students, from day and evening classes of 2016 were tabulated and analyzed in this research. The groups formed for the execution of the methodology were randomized using the individual global average of the previous year of the students, and the groups were composed of 6 to 7 members, maintained throughout the course. During the correction of the tests, the subject of each question and the applied methodology (TBL and TRAD) were identified. Responses of each question were graded separately according to the subject for comparison between methodologies. A total of 88 tests were evaluated. The performance was evaluated through a comparison of the average grade of each question, related to a specific learning methodology. The data were submitted to t-test. Results: The students' overall performance was similar when both methodologies were compared. Students from day class presented higher grades with TBL whilst evening class students presented better performance in questions with traditional lectures. Conclusion: Active learning should be further implemented in Brazilian Dental Schools to change students' habits aiming to improve their personal and social skills besides of professional technical knowledge. (AU)

Objetivo: O objetivo deste estudo foi comparar o desempenho de alunos dos turnos diurno e noturno na prova do primeiro semestre da Disciplina Materiais Dentários da Faculdade de Odontologia de São José dos Campos - UNESP, expostos a aulas tradicionais (TRAD) e Aprendizagem Baseada em Equipe (TBL). Material e Métodos: Os resultados da prova dos alunos, dos turnos diurno e noturno de 2016, foram tabulados e analisados. As turmas utilizadas para a execução da pesquisa foram randomizadas utilizando-se a média global individual do ano anterior dos alunos, sendo as turmas compostas de 6 a 7 integrantes, mantidas ao longo do curso. Durante a correção das provas, foram identificados os assuntos de cada questão e a metodologia aplicada (TRAD e TBL). As respostas de cada questão foram graduadas separadamente de acordo com o assunto para comparação entre as metodologias. Um total de 88 testes foi avaliado. O desempenho dos alunos foi avaliado por meio da comparação da nota média de cada questão, relacionada a uma metodologia específica de aprendizagem. Os dados foram submetidos ao teste t. Resultados: O desempenho geral dos alunos foi semelhante quando comparadas as duas metodologias. Os alunos do período diurno apresentaram notas mais altas no tratamento TBL, enquanto os alunos do período noturno apresentaram melhor desempenho nas questões com aulas expositivas tradicionais. Conclusão: A aprendizagem ativa deve ser mais implementada nos cursos de graduação em Odontologia, no Brasil, para melhorar as habilidades pessoais e sociais dos alunos, além de aperfeiçoar o conhecimento técnico profissional dos discentes (AU).

Effect of phosphorus on the toxicity of zinc to the microalga Raphidocelis subcapitata.

The aim of this study was to evaluate the effect of phosphorus (P) on the toxicity of zinc (Zn) for the alga Raphidocelis subcapitata. P was provided in three concentrations: 2.3 x 10-4 mol L-1, 2.3 x 10-6 mol L-1 and 1.0 x 10-6 mol L-1. Algal cells were acclimated to the specific P concentrations before the start of the experiment. The chemical equilibrium software MINEQL+ 4.61 was employed to calculate the Zn2+ concentration. After acclimated, the algal cells were inoculated into media containing different Zn concentrations (0.09 x 10-6 mol L-1 to 9.08 x 10-6 mol L-1). The study showed that besides the reduction in algal growth rates, phosphorus had an important influence on the toxicity of zinc for microalga. The inhibitory Zn2+ concentration values for R. subcapitata were 2.74 x 10-6 mol L-1, 0.58 x 10-6 mol L-1 and 0.24 x 10-6 mol L-1 for the microalgae acclimated at P concentrations of 2.3 x 10-4 mol L-1, 2.3 x 10-6 mol L-1 and 1.0 x 10-6 mol L-1, respectively. Ecotoxicological studies should consider the interaction between metal concentrations and varying P values to provide realistic data of what occurs in phytoplankton communities in environments.

Chironomus sancticaroli (Diptera, Chironomidae) as a Sensitive Tropical Test Species in Laboratory Bioassays Evaluating Metals (Copper and Cadmium) and Field Testing.

Despite that chironomids are the most widely used benthic insect test species worldwide, little research has been conducted so far with tropical chironomid representatives. This study was designed to evaluate the indigenous midge Chironomus sancticaroli as a candidate test species for use in tropical toxicity assessments. To this end, laboratory water-only toxicity tests were conducted evaluating copper and cadmium. Obtained lethal concentration values were overall comparable or lower than those reported for other chironomids, including those most commonly used in temperate regions (C. riparius and C. dilutus). In addition, C. sancticaroli was deployed in situ in the Monjolinho River (São Paulo State, Brazil), and toxicity of sediment from this river was evaluated in the laboratory. Several field water and sediment quality parameters also were measured to enable correlating these with the effects observed in these toxicity tests. Field sediment toxicity to C. sancticaroli appeared to be related with sediment endosulfan concentrations, whereas effects noted in the in situ test were likely due to low pH values measured in river water. Chironomus sancticaroli appears to be a suitable candidate for inclusion as a test species in tropical toxicity evaluations in both the laboratory and the field.

Effects of the discharge of uranium mining effluents on the water quality of the reservoir: an integrative chemical and ecotoxicological assessment.

The water quality of the Antas reservoir, under the influence of treated effluents from a uranium mining area Ore Treatment Unit (UTM) with acid mine drainage, was investigated. Samples were collected every 3 months from the Antas reservoir (CAB, P41-E and P14) and from the UTM (P41-S). Chemical and acute 48 h toxicity tests using Ceriodaphnia silvestrii and Daphnia magna analyses were carried out to determine the potential environmental risks due to discharging the uranium mine effluents into this reservoir. All the water samples taken from the treated effluent (P41-S) were positively correlated with elevated concentrations of uranium, manganese, aluminum, zinc and fluoride and with high electrical conductivity and pH values, being considered toxic. In November 2014 water samples taken from the reservoir showed chemical concentrations above the legislation limits for fluoride (4.5 mg L-1) uranium (0.082 mg L-1), sulfate (662.4 mg L-1), manganese (1.125 mg L-1) and aluminum (1.55 mg L-1), and in July 2015 for fluoride (2.55 mg L-1), uranium (0.01 mg L-1) and manganese (0.36 mg L-1). The extremely high average value for hardness (543.55 mg L-1) possibly reduced the toxicity potential of this chemical species mixture with respect to the bioindicators. The influence of the variation in water hardness on the toxicity of the cladocerans was discussed.

Toxicity on aquatic organisms exposed to secondary effluent disinfected with chlorine, peracetic acid, ozone and UV radiation.

The toxic potential of four disinfectant agents (chlorine, ozone, peracetic acid and UV radiation), used in the disinfection of urban wastewater, was evaluated with respect to four aquatic organisms. Disinfection assays were carried out with wastewater from the city of Araraquara (São Paulo State, Brazil), and subsequently, toxicity bioassays were applied in order to verify possible adverse effects to the cladocerans (Ceriodaphnia silvestrii and Daphnia similis), midge larvae Chironomus xanthus and fish (Danio rerio). Under the experimental conditions tested, all the disinfectants were capable of producing harmful effects on the test organisms, except for C. xanthus. The toxicity of the effluent to C. silvestrii was observed to increase significantly as a result of disinfection using 2.5 mg L(-1) chlorine and 29.9 mg L(-1) ozone. Ozonation and chlorination significantly affected the survival of D. similis and D. rerio, causing mortality of 60 to 100 % in comparison to the non-disinfected effluent. In experiments with effluent treated with peracetic acid (PAA) and UV radiation, a statistically significant decrease in survival was only detected for D. rerio. This investigation suggested that the study of the ideal concentrations of disinfectants is a research need for ecologically safe options for the treatment of wastewater.

Evaluation of surface water quality in aquatic bodies under the influence of uranium mining (MG, Brazil).

The quality of the water in a uranium-ore-mining area located in Caldas (Minas Gerais State, Brazil) and in a reservoir (Antas reservoir) that receives the neutralized acid solution leaching from the waste heaps generated by uranium mining was investigated. The samples were collected during four periods (October 2008, January, April and July 2009) from six sampling stations. Physical and chemical analyses were performed on the water samples, and the data obtained were compared with those of the Brazilian Environmental Standards and WHO standard. The water samples obtained from waste rock piles showed high uranium concentrations (5.62 mg L(-1)), high manganese values (75 mg L(-1)) and low average pH values (3.4). The evaluation of the water quality at the point considered the limit between the Ore Treatment Unit of the Brazilian Nuclear Industries and the environment (Consulta Creek) indicated contamination by fluoride, manganese, uranium and zinc. The Antas reservoir showed seasonal variations in water quality, with mean concentrations for fluoride (0.50 mg L(-1)), sulfate (16 mg L(-1)) and hardness (20 mg L(-1)) which were low in January, evidencing the effect of rainwater flowing into the system. The concentrations for fluoride, sulfate and manganese were close or above to the limits established by current legislation at the point where the treated mining effluent was discharged and downstream from this point. This study demonstrated that the effluent discharged by the UTM affected the quality of the water in the Antas reservoir, and thus the treatments currently used for effluent need to be reviewed.

Cadmium and Chromium Toxicity to Pseudokirchneriella subcapitata and Microcystis aeruginosa

The toxicity of cadmium and chromium to Pseudokirchneriella subcapitata and Microcystis aeruginosa was evaluated through algal growth rate during 96h exposure bioassays. Free metal ion concentrations were obtained using MINEQL+ 4.61 and used for IC50 determination. Metal accumulations by the microorganisms were determined and they were found to be dependent on the concentration of Cd2+ and Cr6+. IC50 for P. subcapitata were 0.60 µmol L-1 free Cd2+ and 20 µmol L-1 free Cr6+, while the IC50 values for M. aeruginosa were 0.01 µmol L-1 Cd2+ and 11.07 µmol L-1 Cr6+ . P. subcapitata accumulated higher metal concentrations (0.001 -0.05 µmol Cd mg-1 dry wt. and 0.001 -0.04 µmol Cr mg-1 dry wt) than the cyanobacteria (0.001 -0.01 µmol Cd mg-1 dry wt and 0.001 -0.02 µmol Cr mg-1 dry wt). Cadmium was more toxic than chromium to both the microorganisms.

Suitability of Daphnia similis as an alternative organism in ecotoxicological tests: implications for metal toxicity.

The acute toxicity of metals to Daphnia similis was determined and compared to other daphnid species to evaluate the suitability of this organism in ecotoxicology bioassays. To verify the performance D. similis in toxicity tests, we also investigated the effect of Pseudokirchneriella subcapitata at 1 x 10(5) and 1 x 10(6) cells ml(-1) on Cd and Cr acute toxicity to the cladoceran. Daphnid neonates were exposed to a range of chromium and cadmium concentrations in the absence and presence of the algal cells. Metal speciation calculations using MINEQL(+) showed that total dissolved metal concentrations in zooplankton culture corresponded to 96.2% free Cd and 100% free Cr concentrations. Initial total dissolved metal concentrations were used for 48 h-LC(50) determination. LC(50) for D. similis was 5.15 x 10(-7) mol l(-1) dissolved Cd without algal cells, whereas with 1 x 10(5) cells ml(-1), it was significantly higher (7.15 x 10(-7) mol l(-1) dissolved Cd). For Cr, the 48 h-LC(50) value of 9.17 x 10(-7) mol l(-1) obtained for the cladoceran in tests with 1 x 10(6) cells ml(-1) of P. subcapitata was also significantly higher than that obtained in tests without algal cells (5.28 x 10(-7) mol l(-1) dissolved Cr). The presence of algal cells reduced the toxicity of metals to D. similis, as observed in other studies that investigated the effects of food on metal toxicity to standard cladocerans. Comparing our results to those of literature, we observed that D. similis is as sensitive to metals as other standardized Daphnia species and may serve as a potential test species in ecotoxicological evaluations.

Evaluation onto life cycle parameters of Ceriodaphnia silvestrii submitted to 36 days dietary copper exposure.

The present study aimed to investigate the response of several life history parameters (body length and age of primipara, duration of embryonic development, maximum body length, reproduction and survival) of the zooplankton Ceriodaphnia silvestrii while exposed to copper contaminated algae Pseudokirchneriella subcapitata. In order to evaluate chronic exposure on the animal's life history, long-term experimental design was used. Cladocerans were fed with a dietary copper concentration ranging from 3 to 68 fg Cu cell(-1). Low waterborne copper exposure (around 10(-10)molL(-1) free Cu(2+) ions) was kept in the experiments. The results showed that by exposure of cladocerans during 7 days to contaminated food with 68 fg Cu cell(-1), a significant reduction in neonate production, survival and body size were obtained. Inhibition on egg production of zooplankton at 38 fg Cu cell(-1) were observed in 36 days chronic dietary copper exposure. The importance of entire life cycle study to better evaluate cladoceran responses to chronic dietary metal exposure was demonstrated.

Change in life cycle parameters and feeding rate of Ceriodaphnia silvestrii Daday (Crustacea, Cladocera) exposure to dietary copper.

Changes in life cycle parameters (survival, growth, reproduction) and feeding rate of the tropical cladoceran Ceriodaphnia silvestrii as affected by Cu contaminated algae Pseudokirchneriella subcapitata were investigated. The dietary copper exposure ranged from 3 x 10(-15) to 68 x 10(-15) g Cu algal cell(-1). Low waterborne copper exposure (around 10(-10) mol l(-1) free Cu2+ ions) was kept in the experiments. The results show an increasing toxic effect on C. silvestrii with copper increase in algal cells; at the highest copper exposure, all life cycle parameters were significantly affected. A concentration of 38 x 10(-15) g Cu algal cell(-1) reduced egg hatching percentile and the number of neonates produced per female, but did not cause any statistically significant effect on animals survival nor to the number of eggs produced per female. The following sequence of events was observed from the lowest to the highest copper contamination: reproduction, feeding rate, body length and, at last, survival was affected. We conclude that algal cells are an important route of copper exposure and toxicity to cladocerans.

Effects of interactions between algal densities and cadmium concentrations on Ceriodaphnia dubia fecundity and survival.

The influence of different densities of the algae Pseudokirchneriella subcapitata on the chronic toxicity of cadmium to Ceriodaphnia dubia was investigated. The importance of algal cells as a source of metal to zooplankton was studied by exposing P. subcapitata cells to free cadmium ions and supplying the algae as food to C. dubia. The results of a bifactorial analysis (metal versus food levels) showed that metal toxicity to zooplankton was dependent on food level. Significant toxic effects on the fecundity and survival of C. dubia were observed at low metal concentrations with high algal density. Algae contaminated with Cd(2+) were less toxic to cladoceran than was the Cd(2+) in solution. Green algae retained cadmium and released low metal concentration in the test medium. We concluded that algal cells are an important route of exposure to metal and a factor that has an appreciable influence on the expression of metal toxicity to daphnids.