Abstract In South America, Solenopsis saevissima and S. invicta are the most common fire ants. Nests are founded in areas under anthropic interference like urban or rural areas, but S. invicta is found preferentially in those with the greatest anthropic interference. However, we do not know the rates at which they exist in anthropized areas next to high density of native vegetation. Areas with 60 to 90% of native Atlantic Forest were selected to verify the occurrence of both species in rural and urban areas. We investigated the molecular diversity and applied the reconstruction of the ancestral state analysis for each species. A total of 186 nests were analyzed and we found that the two species had the same proportion in the urban area. However, S. saevissima had a higher rate of prevalence in the rural area, in addition to having a greater number of haplotypes and ancestry associated with this type of habitat for the region. S. invicta had the same number of haplotypes in both rural and urban regions, and less haplotypic diversity. We conclude that S. saevissima is a species typically associated with rural areas and S. invicta, although present, is not dominant in urban areas.

The sulfur related thermochemical water-splitting cycles are an important class of chemical processes considered for hydrogen production. Recently, the magnesium sulfate thermal decomposition has been reported as a potential unit operation in one of these cycles. Therefore, some interest has been observed in the use of catalysts to lower the activation energy of such reactions. In this context, the present manuscript reports the thermodynamics and kinetics modeling results associated with this reaction system in the presence of a Pd catalyst supported over γ-Al2O3. The presence of such species is responsible for shifting the decomposition temperature to lower values in at least 100 °C. It was observed that the magnesium content is still oriented towards MgO formation. The obtained results indicate that the Pd/Al2O3 catalyst could be a good alternative in reducing the thermal decomposition temperature as its presence was responsible for diminishing the process activation energy from 368.2 to 258.8 kJ.mol−1.

Eletrocatalisadores Pd/C, Au/C e PdAu/C com diferentes razões atômicas foram preparados utilizando-se irradiação por feixe de elétrons e testados na oxidação eletroquímica de glicerol em uma célula alcalina a glicerol direto (ADGFC). Os difratogramas de raios X (XRD) evidenciaram a presença de fases ricas em Pd (fcc) e Au (fcc). As análises de voltametria cíclica (CV) e cronoamperometria indicaram que o eletrocatalisador com razão atômica 50:50 demonstrou atividade superior para a oxidação eletroquímica do glicerol a temperatura ambiente. As análises de infravermelho com transformada de Fourier no modo de refletância total atenuada (ATR-FTIR) in situ identificaram como principais produtos da oxidação eletroquímica do glicerol: 1,3-diidroxi-2-propanona, gliceraldeído e glicolato. Os experimentos em célula unitária foram realizados entre 50 e 90 ºC e foi constatado que o melhor desempenho aconteceu a 80 ºC.

Pd/C, Au/C and PdAu/C electrocatalysts with different atomic ratios prepared using electron beam irradiation were tested for glycerol electrooxidation in single alkaline direct glycerol fuel cell (ADGFC). X-ray diffractograms (XRD) of PdAu/C electrocatalysts showed the presence of Pd (fcc) and Au (fcc) phases. Cyclic voltammetry (CV) and chronoamperometry showed that PdAu/C electrocatalyst with Pd:Au atomic ratio of 50:50 demonstrated superior activity for glycerol electrooxidation, at room temperature. In situ Fourier transform infrared spectroscopy by attenuated total reflectance (ATR-FTIR) experiments were performed for the electrocatalysts, identifying oxalate, glycerate ion, 1,3-dihydroxy-2-propanone, glyceraldehyde and glycolate as products of glycerol electrooxidation. Experiments with single ADGFC were carried out from 50 to 90 ºC, using Pd/C electrocatalyst; the best performance was obtained at 80 ºC.

Este estudo investiga o efeito promotor de anodos eletrocatalisadores do tipo PtSnIr/C (1:1:1), preparados pelo método de precursor polimérico, na reação de oxidação de etanol em uma célula a combustível de etanol direto (DEFC). Todos os materiais usados foram metal 20% m/m com relação a carbono. Análise por espectroscopia fotoelétrica de raios X (XPS) mostrou a presença de Pt, PtOH2, PtO2, SnO2 e IrO2 na superfície do eletrocalisador, indicando uma possível estrutura de partícula revestida. Análise por difratometria de raios X (XRD) indicou Pt e Ir metálicos assim como a formação de uma liga com Sn. Utilizando eletrocatalisadores do tipo PtSnIr/C preparados para este estudo com quantidades de Pt duas vezes menor que em eletrocatalisadores do tipo PtSn/C E-tek, foi possível obter a mesma densidade de potência máxima encontrada para o material comercial. O produto de reação principal foi ácido acético provavelmente devido a presença de óxidos, neste caso o mecanismo bifuncional é predominante, mas um efeito eletrônico não deve ser descartado.

This study investigates the promoting effect of PtSnIr/C (1:1:1) electrocatalyst anode, prepared by polymeric precursor method, on the ethanol oxidation reaction in a direct ethanol fuel cell (DEFC). All of the materials used were 20% metal m/m on carbon. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of Pt, PtOH2, PtO2, SnO2 and IrO2 at the electrocatalyst surface, indicating a possible decorated particle structure. X-ray diffractometry (XRD) analysis indicated metallic Pt and Ir as well as the formation of an alloy with Sn. Using the PtSnIr/C electrocatalyst prepared here with two times lower loading of Pt than PtSn/C E-tek electrocatalyst, it was possible to obtain the same maximum power density found for the commercial material. The main reaction product was acetic acid probably due to the presence of oxides, in this point the bifunctional mechanism is predominant, but an electronic effect should not be discarded.

O uso eficiente da água e a diversificação ambiental são fundamentais para o equilíbrio e a sustentabilidade dos sistemas orgânicos de produção de tomate. O presente estudo teve por objetivo avaliar a produção de tomate de mesa em cultivo solteiro e consorciado com coentro com irrigação por aspersão e gotejamento, em sistema orgânico. O experimento foi conduzido em área de produção orgânica no Distrito Federal. O delineamento foi blocos ao acaso, com tratamentos dispostos num arranjo fatorial 2 x 2 (dois sistemas de irrigação x dois sistemas de cultivo). Não houve interação significativa entre os fatores avaliados, assim como não houve efeito do sistema de cultivo sobre as variáveis avaliadas. Embora o ciclo do tomateiro irrigado por gotejamento tenha diminuído, a produtividade de frutos não foi afetada pelos sistemas de irrigação. A maior redução de estande verificada na aspersão foi compensada por um aumento no número de frutos por planta, sem variação na massa por fruto. O menor volume de solo explorado pelas raízes do tomateiro associado à maior incidência de traça-do-tomateiro (Tuta absoluta) e principalmente de oídio (Leveillula taurica) pode ter limitado a produtividade do tomateiro irrigado por gotejamento. A taxa de frutos podres na aspersão foi o dobro da verificada no sistema por gotejamento.

The efficient use of water and the environmental diversity are crucial to the balance and sustainability of the organic production system of tomatoes. The present study aimed to evaluate the organic production of tomato cultivated as a single crop and in consortium with coriander, under sprinkler and drip irrigation. The experiment was carried out at an organic production area on the Federal District of Brazil. The experimental design was randomized blocks with treatments arranged in a 2 x 2 factorial (two irrigation systems x two cropping schemes). No significant interaction between the both factors occurred, and there was no significant effect of the cropping scheme over the evaluated variables. Although the crop cycle has been reduced when tomato was drip irrigated, the fruit yield was not affected by the irrigation systems. The larger reduction in the stand of plants observed under sprinkler irrigation has been compensated by an increase in the number of fruits per plant, without a change on the fruit mass. The smaller volume of soil explored by the tomato roots associated with the higher incidence of South American tomato pinworm (Tuta absoluta) and mainly powdery mildew (Leveillula taurica) may have limited the yield of drip irrigated tomato. The fruit decay rate on sprinkle irrigated plants was twice the rate found on the drip irrigated system.

The oxygen reduction reaction was studied in alkaline media using manganese oxides obtained from spent batteries as electrocatalysts. Three processes were used to recover manganese oxides from spent batteries. The particles obtained were in the range from 8 to 11 nm. The electrochemical experiments indicated a good electrocatalytic activity toward oxygen reduction using the different samples and showing approximately a direct transference of 4 electrons during the process. Even though all the processes were efficient, the best result was observed for the prepared sample using reactants of low cost.