The world faces a global concern of replacing fossil fuels with renewable and clean energy sources due to the harmful carbon emissions that contribute to climate change and the depletion of these non-renewable resources. To combat this issue, there is a worldwide effort to find alternatives to fossil fuels and develop new energy generation technologies. One promising alternative is solar energy, which several countries include as an energy source. While photovoltaic power has been used, expanding knowledge in this area is needed. Educating people about the importance of critical thinking regarding renewable, carbon-free energy technology like solar energy can highlight its significance in the contemporary world. In this study, we use light-emitting diodes (LEDs) to simulate the behaviour of a photovoltaic solar cell when exposed to sunlight and describe the relationships among electrical quantities, such as potential difference, current, and power. nonrenewable non resources issue technologies source used needed carbonfree free study lightemitting light emitting LEDs (LEDs quantities difference current

OBJECTIVE: The aim of this study was to evaluate the effect of C-factor and light-curing protocol on gap formation in composite resin restorations. Material and METHODS: Cylindrical cavities with 5.0 mm diameter and three different depths (A=1.0, B=2.0 and C=3.0 mm) were prepared on the occlusal surface of 30 human molars and restored in a single increment with P 60. The composite resin was light-cured according to two protocols: standard - 850 mW/cm² / 20 s and gradual - 100 up to 1000 mW/cm² / 10 s + 1000 mW/cm² / 10 s. After storage in distilled water (37°C/7 days), the restorations were cut into three slices in a buccolingual direction and the gap widths were analyzed using a 3D-scanning system. The data were submitted to ANOVA and Student-Newman-Keuls test (alpha=0.05). RESULTS: ANOVA detected a significant influence for the C-factor and light-curing protocol as independent factors, and for the double interaction C-factor vs. light-curing protocol. Cavities with higher C-factor presented the highest gap formation. The gradual light-curing protocol led to smaller gap formation at cavity interfaces. CONCLUSIONS: The findings of this study suggest that the C-factor played an essential role in gap formation. The gradual light-curing protocol may allow relaxation of composite resin restoration during polymerization reaction.

O objetivo deste trabalho foi comparar a economicidade de algumas técnicas de recuperação de pastagens, ao longo de um período, avaliando o desempenho animal sob pastejo rotacionado. As atividades foram desenvolvidas em Brasilândia, MS, em seis módulos de cinco hectares cada. Os módulos T1 (milho + Brachiaria brizantha), T2 (arroz + B. brizantha) e T3 (arroz + B. brizantha + Calopogonium mucunoides) foram renovados de acordo com a técnica preconizada pelo Sistema Barreirão. O módulo T4 foi formado de acordo com método convencional da região com B. brizantha. Os módulos T5 e T6 foram selecionados nas proximidades dos demais módulos como testemunhas, predominando a B. humidicola no módulo T5 e B. humidicola e B. decumbens no módulo T6. A avaliação econômica foi baseada na produção de grãos, ganho de peso e na lotação animal. Os resultados encontrados nos sistemas analisados, nos módulos T1, T2, T3 e T4 demonstram que a exploração da pecuária bovina de corte, no pasto recuperado, é uma atividade economicamente lucrativa, e que os módulos T1, T2 e T3 apresentam vantagem comparativa, devido à produção de grãos que cobre parte dos custos de formação da pastagem.

The aim of this study was to compare the economic viability of some technologies for recovery of degraded pastures, for a period of time, evaluating animal development under rotational grazing. The activities were conducted in Brasilândia, MS, Brazil, studying six modules of 5 ha each. Modules T1 (corn + Brachiaria brizantha), T2 (rice + B. brizantha), and T3 (rice + B. brizantha + Calopogonium mucunoides) had been renewed following the procedures recomended by the "Barreirão System". Module T4 had been formed according to traditional regional procedures, with B. brizantha. Modules T5 and T6 were selected in the vicinity of the others, to serve as controls; B. humidicola was predominant in module T5, whereas module T6 was predominantly formed by B. humidicola and B. decumbens. Economic evaluation was based on cereal production, live weight gain and stocking rate. It was observed that in modules T1, T2, T3, and T4, exploration of beef cattle grazing on recovered pastures is a profitable activity. Pasture renewal according to agricultural modules T1, T2, and T3 have advantages over the traditional models due to the cereal production which defrays the cost to recover the pastures.