Metal-based catalysts are indispensable in modern chemistry and one of the biggest challenges for industrial applications is to quantify their performance and stability. The metrics of performance can be obtained in terms of the turnover number and turnover frequency, and the stability might be associated with the leaching of the heterogeneous catalysts. Thus, metal quantification is the starting point to understand and evaluate the features of catalysts. Among the technologies for metal determination, spectrophotometric analysis stands out for being cheap and easy to perform. However, the challenge is the sample preparation to direct quantification from the heterogeneous materials. Herein, it is shown how important is the photochemical pre-treatment for the quantification of the total iron from heterogeneous thin films composed of iron-based materials. The photochemical approach was used to ensure a full dissociation of iron ions before the quantification. This method was revealed to be highly effective and precise, having a wide range of applications for different iron-based catalysts. Metalbased Metal based frequency Thus determination perform However materials Herein pretreatment pre treatment ironbased precise

The water oxidation is the limiting step in the water-splitting process. Given this scenario, the development of new catalysts is essential in this field. The emergent demand is the use of Earth-abundant elements and catalysts with high performance under mild conditions. Because of this, catalysts such as Prussian Blue analogues (PBA) have been receiving a lot of attention in recent years. In addition, working under neutral conditions allows us to take advantage of the modification of conductive polymeric 3D printed electrodes (3DPE) with Prussian Blue. Thus, we described in this work the development of the polymeric 3D printed electrodes modified by cobalt-Prussian Blue and their performance in the water oxidation process. The 3D printed electrodes modified with Co3[Co(CN)6]2 (Co-Co PBA) have a Tafel slope of 343 mV dec−1 while those modified with Co3[Fe(CN)6]2 (Co-Fe PBA) have a Tafel slope of 378 mV dec−1. This means that both catalysts have the same mechanism for the water oxidation process. On the other hand, the overpotential of Co-Co PBA in 3DPE is lower than the value observed by Co-Fe PBA in 3DPE suggesting the best electrocatalytic activity for Co-Co PBA catalyst.

Com o objetivo de se estudar o efeito de doses de boro sobre as características morfofisiológicas de sementes e a produção de girassol, cultivar Embrapa V122-2000, instalou-se um experimento em 17/11/2000, em área experimental da UNESP/FCAV, Jaboticabal, SP, em Latossolo Vermelho eutrófico de textura média. O delineamento foi o de blocos casualizados, com cinco doses de boro (0, 1, 2, 3 e 4 kg ha-1) em quatro repetições. Após o florescimento pleno (80-90% de flores abertas) se avaliaram semanalmente, as características das sementes: comprimento, largura e espessura, massa seca, concentração e conteúdo de água, primeira contagem da germinação, germinação final e teor de óleo. Pelos resultados obtidos não se constatou efeito significativo da aplicação de boro nas características das sementes avaliadas aos 49 dias após o florescimento pleno da cultura, o que foi atribuído ao teor inicial de boro no solo, 0,22 mg dm-3 (extraído com solução de BaCl2 1,25 g L-1) que, além de considerado médio, deve ter sido suficiente para o crescimento e desenvolvimento das sementes de girassol. A produtividade média foi de 2.559 kg ha-1.

An experiment was carried out in order to evaluate effects of boron applied to soil on the morphophysiological characteristics of sunflower seed (achene). The experiment was installed on November 17, 2000 in an experimental area at São Paulo State University - UNESP/FCAV, Jaboticabal, SP, in an oxisoil with the sunflower variety Embrapa V122-2000. The experimental design was a completely randomized block, with five doses of boron (0, 1, 2, 3 and 4 kg ha-1) with four replications. After full bloom (80-90% of open flowers), the following characteristics were evaluated during seven weeks: length, width and thickness, seed dry mass, water concentration and content, first counting of germination, final germination and oil content. Seed yield was also evaluated. There was no significant effect of boron application on seed characteristics evaluated 49 days after full bloom, and this result was associated to the initial content of boron in the soil (0.22 mg dm-3 extracted with BaCl2 1.25 g L-1), which is considered an average value. The mean yield of seeds was 2,559 kg ha-1.

A 4,5-diamina-2,6-dimercaptopirimidina (DADMcP) constitui uma molécula multifuncional que apresenta uma tautomeria bastante complexa, com nove formas isoméricas possíveis. O estudo da tautomeria nesse composto foi realizado por meio da espectroscopia FTIR em associação com cálculos ab-initio HF/SCF e DFT. De acordo com os resultados teóricos, três tautômeros são favorecidos energeticamente, sendo a tiona a forma a mais estável. Os espectros vibracionais das formas tautoméricas mais estáveis foram simulados através de cálculos de DFT, permitindo a atribuição e elucidação do quadro complexo de bandas vibracionais observado experimentalmente, envolvendo a mistura de isômeros.

The 4,5-diamine-2,6-dimercaptopyrimidine (DADMcP) compound is an interesting multifunctional species exhibiting a rather complex tautomerism, encompassing nine tautomeric forms. Investigation of tautomerism in this compound has been carried out by means of FTIR spectroscopy, in association with ab-initio HF/SCF and DFT calculations. According to this study three tautomers are energetically favored; the thione form being the most stable one. The theoretical vibrational spectra of such tautomeric forms have been successfully simulated by means of DFT calculations, allowing the elucidation and assignment of the complex composition of the vibrational bands observed for the mixture of isomers.