Development of Israeli mango cultivars in the Brazilian semiarid region

O objetivo deste trabalho foi avaliar o desempenho adaptativo inicial de cultivares de mangueiras israelenses cultivadas na região do Submédio do Vale do São Francisco, Brasil. O experimento foi realizado de janeiro de 2019 a julho de 2020, tendo-se utilizado mudas das cultivares Omer e Shelly, aos seis meses após o transplante, em espaçamento de 3×6 m. O delineamento experimental foi em blocos ao acaso, em arranjo fatorial 2×3, correspondente às duas cultivares de mangueiras israelenses e ao número de ramos após a poda de formação (três, quatro e cinco ramos), com quatro repetições. Foram analisadas variáveis biométricas, bioquímicas e fotossintéticas, que diferiram entre as épocas de avaliação após as podas. A cultivar Omer é mais vigorosa que a Shelly, e a poda formativa com três, quatro e cinco ramos é recomendada para ambas as cultivares de manga nas condições de cultivo do Vale do São Francisco.The objective of this work was to evaluate the initial adaptive performance of Israeli mango tree cultivars grown in the submedian region of the São Francisco Valley, Brazil. The experiment was carried out from January 2019 to July 2020 using seedlings of the Omer and Shelly cultivars, at six months after transplanting, at a 3×6 m spacing. The experimental design was randomized complete blocks in a 2×3 factorial arrangement, corresponding to the two Israeli mango tree cultivars and the number of branches after formative pruning (three, four, and five branches), with four replicates. Biometric, biochemical, and photosynthetic variables were analyzed, differing between the evaluation times after pruning. The Omer cultivar is more vigorous than Shelly, and formative pruning with three, four, and five branches is recommended for both mango cultivars under the cultivation conditions of the São Francisco Valley

SABER TREINAR A SI MESMO: PORQUE E COMO DEVEMOS ENSINAR TREINAMENTO NAS AULAS DE EDUCAÇÃO FÍSICA?

O texto apresenta argumentações cientificas sobre o treino corporal na escola a partir de uma experiência concreta na Escola Municipal Teodoro Sampaio, Salvador, Bahia, Brasil

Influência do método de preparação de eletrocatalisadores PtRu/C sobre a atividade catalítica frente à reação de oxidação de etanol em meio ácido

In this work the influence of variations in the borohydrate reduction method on the properties of PtRu/C electrocatalysts was investigated. The electrocatalysts were prepared using 1:1 ; 2:1; 5:1; 50:1 and 250:1 molar ratios of NaBH4 to metals. The reduction was also performed by dripping or by fast addition of the solution. The results showed that PtRu nanoparticles obtained by fast addition had the smallest crystallite sizes. It was also noted that the catalytic activity increased as the borohydrate:metal molar ratio increased. The PtRu/C electrocatalyst (50:1) obtained by fast addition presented the best catalytic activity for ethanol electro-oxidation

Influência do método de preparação de eletrocatalisadores PtRu/C sobre a atividade catalítica frente à reação de oxidação de etanol em meio ácido Influence of method of preparation of PtRu/C electrocatalysts on the catalytic activity for the ethanol oxidation reaction in acidic medium

In this work the influence of variations in the borohydrate reduction method on the properties of PtRu/C electrocatalysts was investigated. The electrocatalysts were prepared using 1:1 ; 2:1; 5:1; 50:1 and 250:1 molar ratios of NaBH4 to metals. The reduction was also performed by dripping or by fast addition of the solution. The results showed that PtRu nanoparticles obtained by fast addition had the smallest crystallite sizes. It was also noted that the catalytic activity increased as the borohydrate:metal molar ratio increased. The PtRu/C electrocatalyst (50:1) obtained by fast addition presented the best catalytic activity for ethanol electro-oxidation

Cu@PtRu Core–Shell Nanostructured Electrocatalysts Anchored on Reduced Graphene Oxide toward Methanol Oxidation

This work reports the influence of a reduced graphene oxide (rGO) support on the catalytic performance of Cu@PtRu/rGO electrocatalysts toward methanol oxidation in an acidic medium. These electrocatalysts are synthesized via a two-step reduction method; the first step utilizes ethylene glycol for the reduction of Cu2+ ions, forming Cu/rGO. In the second step, spontaneous redox reactions take place, in a process known as galvanic displacement, where the Pt2+ and Ru3+ species are reduced to form PtRu layers, and the copper is partially oxidized to the solution. Then, the Cu@PtRu/rGO core–shell is produced, comprising Cu in the inner structure (core) and PtRu on the outer part (shell). To compare the catalytic performance of the prepared nanocatalysts (NCs), Pt/C, PtRu/C, and Cu@PtRu/C are also synthesized on Vulcan XC-72R carbon. All catalysts are characterized via X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Cyclic voltammetry (CV) and chronoamperometry (CA) are employed to measure the electrochemical performance. The core–shell/rGO combination is superior in catalytic activity to the traditional Pt/C, PtRu/C, and Cu@PtRu/C catalysts for the methanol oxidation reaction. These results suggest that Cu@PtRu/rGO exhibits a high bulk activity for methanol electrooxidation, a high stability, and a high tolerance to CO poisoning, meaning it is possible to reduce the platinum loading in proton-exchange membrane fuel cells (PEMFCs)