Rice Husk Ash Modified with Vanadium Pentoxide

Rice husk collected in Barreiras City, Bahia, Brazil was converted to rice husk ash (RHA) by acidic or basic leaching, followed by calcination. The resulting RHA was modified with vanadium pentoxide (2, 5, or 10 mass% of V2O5).  The modified RHA samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). RHA exhibited FTIR bands associated with silica. After modification of acid-leached RHA with vanadium, the XRD data indicated the formation of V2O5 phases. Base-leached RHA modified with vanadium pentoxide showed the presence of the V2O5 phase only in the sample containing 10 mass% V2O5. The FTIR data indicated the formation of cristobalite, where bands associated with Si-O-V interactions were observed only for the sample with 10 mass% V2O5 prepared with acid-leached RHA. DOI: http://dx.doi.org/10.17807/orbital.v9i2.91

Remoção de Carbofurano em Água Empregando Resíduos Agroindustriais como Adsorventes

In this study aimed to evaluate the possibility of using industrial boiler ash and rice husk ash in removing the commercial pesticide (carbofuran) in aqueous solution. These solids were collected in the Barreiras/BA, were heat treated and characterized by XRD and FT-IR. The adsorption experiments were performed in batch and the carbofuran removal was quantified using the spectrophotometry in the UV region. XRD data showed high silica content in boiler ash, which was reinforced by FT-IR analyses, showing the band FT-IR associated with presence of silica. In the FT-IR analysis of rice husk ash, this band relative to silica also were observed. The potential of adsorption of the ash industrial boiler and rice husk ash was verified obtaining significant results in the removal of carbofuran at low concentrations (2 mg/L), showing 100% of removal of pesticides from 720 min, used the ash industrial boiler, giving these materials a promising character as adsorbents. In the kinetic study of carbofuran adsorption, the mechanism of pseudo-second-order was better adjusted using the RHA as adsorbent, with a correlation coefficient (R2) of 0.997. The adsorption equilibrium was adjusted better to model of adsorption isotherm of Freundlich with a correlation coefficient of 0.999. DOI: http://dx.doi.org/10.17807/orbital.v1i1.71

Rice Husk Ash Modified with Vanadium Pentoxide

Rice husk collected in Barreiras City, Bahia, Brazil was converted to rice husk ash (RHA) by acidic or basic leaching, followed by calcination. The resulting RHA was modified with vanadium pentoxide (2, 5, or 10 mass% of V2O5).  The modified RHA samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). RHA exhibited FTIR bands associated with silica. After modification of acid-leached RHA with vanadium, the XRD data indicated the formation of V2O5 phases. Base-leached RHA modified with vanadium pentoxide showed the presence of the V2O5 phase only in the sample containing 10 mass% V2O5. The FTIR data indicated the formation of cristobalite, where bands associated with Si-O-V interactions were observed only for the sample with 10 mass% V2O5 prepared with acid-leached RHA. DOI: http://dx.doi.org/10.17807/orbital.v9i2.91

Isaias Alves e as aproximações entre a psicologia educacional e a educação matemática

Resumo Partindo do relatório de viagem aos Estados Unidos do educador baiano Isaias Alves, o presente artigo tem como objetivo explorar as aproximações entre a psicologia educacional e a educação matemática na década de 1930, e de que forma a primeira promoveu a circulação de teorias/autores na última, principalmente no que diz respeito ao intercâmbio entre Brasil e Estados Unidos. Enquanto aproximação teórico-metodológica, alguns dos conceitos operados são apropriação, circulação (de ideias/objetos/sujeitos) e discurso autorizado, com base em autores como Roger Chartier (1990, 2002, 2009), Serge Gruzinski (2001a, 2001b) e Michel de Certeau (2012). Além do relatório de viagem, outras fontes mobilizadas foram publicações de Isaias (livros e artigos), programas de ensino dos Institutos de Educação do Rio de Janeiro e de São Paulo, manuais pedagógicos e jornais disponíveis no acervo da Hemeroteca Digital da Biblioteca Nacional. Entre as constatações, percebe-se que o relatório de viagem de Isaias Alves deu visibilidade às discussões e publicações do psicólogo estadunidense Edward Lee Thorndike voltadas à educação matemática. Ainda, que o diálogo estabelecido entre a psicologia educacional e a educação matemática estava fortemente vinculado às discussões sobre testes e que a forma como Isaias Alves lia e dava a ler a educação matemática ocorria a partir do viés psicológico

Crowning in weed control and initial development of native forestry species

Dois experimentos foram conduzidos a campo em Paraguaçu Paulista/SP, entre dezembro de 2004 e março de 2006, objetivando avaliar o controle de plantas daninhas na forma de coroamento de mudas das espécies florestais nativas aroeira pimenteira (Schinus terebinthifolius Raddi) e ingá (Inga fagifolia Willd). O delineamento experimental utilizado foi o de blocos casualizados com seis tratamentos e quatro repetições. Os tratamentos foram constituídos por: capina constante das plantas daninhas durante o período de 60 a 420 dias após o plantio das mudas (DAPM), na forma de coroamento da área da copa das plantas, representados pelos diâmetros: 0,5; 1,0; 1,5; 2,0 m; sem capina e 1,0 m utilizando o herbicida glyphosate (0,72 kg e.a.ha-1) em aplicação única aos 60 DAPM. O manejo das plantas daninhas através do coroamento das mudas em diâmetro de 2,0 m proporcionou o melhor desenvolvimento inicial das espécies florestais aroeira pimenteira e ingá, evidenciando a alta sensibilidade à competição por recursos do meio. A aplicação única de glyphosate em 1,0 m de diâmetro aos 60 DAPM mostrou-se ineficiente para o desenvolvimento inicial das espécies florestais nativas estudadas.terebinthifolius Raddi and Inga fagifolia Willd, two experiments were carried out in Paraguaçu Paulista/SP from December, 2004 to March, 2006. Six experimental treatments were set in a randomized complete block design with four replications. The treatments were: constant hand-hoeing weed control from 60 to 420 days after seedlings planting (DAPM) forming a crown represented by the following diameters: 0.5; 1.0; 1.5; 2.0m; without hoeing and 1.0 meter by using glyphosate herbicide (0.72 kg a.e.ha-1) in a single application at 60 DAPM. Weed management through crowning at 2.0m provided better initial development for both analyzed species, which shows high sensibility to the competition for environmental resources. The single application of glyphosate at 1.0 meter at 60 DAPM was considered inefficient for the initial development of those species

Secretome analysis of Trichoderma atroviride T17 biocontrol of Guignardia citricarpa

The fungal species Guignardia citricarpa is an important pathogen in citriculture. Members of the fungal genus Trichoderma are recognized as biocontrol agents but studies on the interactions between both fungi are scarce. This study aimed to identify extracellular proteins secreted by Trichoderma atroviride T17 that are related to the control of G. citricarpa. Two-dimensional gel electrophoresis (2D) was used to study the patterns of proteins secreted by T. atroviride T17 in medium containing glucose (control) and in medium containing G. citricarpa GC3 inactivated mycelium. We identified 59 of the 116 spots differentially expressed (50.86%) by LC–MS/MS. Of these, we highlight the presence of glycoside hydrolases (CAZy families 3, 43, 54, 76 and 93), chitinase, mutanase, a-1,3-glucanase, a-1,2-mannosidase, carboxylic hydrolase ester, carbohydrate-binding module family 13, glucan 1,3-b-glucosidase, a-galactosidase and Neutral protease 2. These proteins are related to mycoparasitism processes, stimuli and therefore to the biological control of pathogens. The results obtained are in agreement with reports describing an increase in the secretion of proteins related to mycoparasitism and biological control and a reduction in the secretion of proteins related to the metabolism of Trichoderma species grown in the presence of the pathogen. Moreover, these results are pioneer in understanding T. atroviride interaction with G. citricarpa. For the first time, we identified potential candidate proteins that may have a role in the antagonism mechanism of G. citricarpa by T. atroviride T17. Thus our results shed a light into the molecular mechanisms that T. atroviride use to control G. citricarpa