It is well known that citrus plants that have been infected by Xylella fastidiosa display nutritional deficiencies, probably caused by production of extracellular polymers by the bacteria that block normal nutrient flow through the xylem. The aim of this work was to study the mineral composition of specific foliar areas in different stages of infection in citrus. Thus, the concentrations of macro and micronutrients in leaves of citrus infected by X. fastidiosa were measured. Samples from four infected citrus orchards in the State of São Paulo, Brazil, were respectively collected from Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto and Paraíso counties. The presence of X. fastidiosa in leaves was confirmed by polymerase chain reaction (PCR) using specific PCR primers. To understand the variation in leaf-nutrient content in citrus plants, we used foliar nutrient values from control (non-symptomatic) plants as a reference. Chemometric analysis showed that the deficiency of P and K in symptomatic trees for all orchards and high concentrations of Fe, Mn and Zn were observed in chlorotic areas, although other studies revealed deficiency of zinc in leaves. This is the first report showing that a correlation between chlorotic citrus leaf and higher concentrations of Fe, Mn and Zn are observed when infected and healthy plants were compared.Keywords: citrus, nutrition, Xylella fastidiosa, CVC disease, chemometry. Deficiência nutricional em citros com sintomas da doença da clorose variegada dos citros ResumoJá é bem conhecido que cultivares cítricas que foram infectadas pela bactéria Xylella fastidiosa apresentam deficiências nutricionais devido à produção de polímero extracelular por esta bactéria, o qual bloqueia o fluxo normal de nutriente pelo xilema. O objetivo deste trabalho foi o de estudar a composição mineral em áreas foliares específicas em diferentes fases de infecção na planta. Assim, as concentrações de macro e micronutrientes em folhas de citros infectados por X. fastidiosa foram quantificadas. Foram coletadas amostras de quatro pomares cítricos infectados localizados em: Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto e Paraíso, no Estado de São Paulo. A presença de X. fastidiosa em folhas foi confirmada através de reação da polimerase em cadeia (PCR) usando iniciadores específicos. Para entender a variação no conteúdo de nutriente foliar em plantas cítricas, utilizou-se de valores de nutrientes foliares de plantas não sintomáticas (controle) como referência. A análise quimiométrica mostrou que a deficiência de P e K em plantas sintomáticas e concentrações altas de Fe, Mn e Zn foram presentes em áreas foliares cloróticas, embora outros estudos mostrem a deficiência de zinco em folhas. Este é o primeiro relato indicando que uma correlação entre folhas cítricas cloróticas e elevadas concentrações de Fe, Mn e Zn foi observada quando plantas infectadas e saudáveis foram comparadas.Palavras-chave: citros, nutrição, Xylella fastidiosa, doença do CVC, quimiometria. BIOLOGYSilva-Stenico...
O ácido fólico tem sido identificado como uma das mais importantes vitaminas para a função normal do metabolismo humano. A deficiência de ferro é um sério problema de saúde que afeta uma grande proporção da população do mundo. No Brasil, foi publicada uma regulamentação indicando que farinhas de milho e trigo devem ser fortificadas com ácido fólico e ferro. O objetivo deste trabalho foi avaliar os níveis de ácido fólico e ferro em algumas farinhas enriquecidas. A quantificação de ambos nutrientes indicou que a concentração de ácido fólico variou entre 96 a 558 µg per 100 g (em milho) e 73 a 233 µg per 100g (em trigo) e de 3,8 a 8,7 mg per 100 g (em milho) e 4,6 a 7,4 mg per 100g (em trigo) para ferro. Portanto, a população brasileira parece estar exposta a concentrações inadequadas de ácido fólico e ferro quando farinhas de trigo e milho são consumidas.Folic acid has been identified as one of the most important vitamins for normal human metabolic function. Iron deficiency is a serious health problem affecting a large proportion of the world population. In Brazil, an issue has been ruled requiring that corn and wheat flours must be fortified by the addition of folic acid and iron. The aim of this work was to evaluate the levels of folic acid and iron in some enriched flours. The successful quantification of both nutrients indicated that the levels of folic acid are in the range of 96 to 558 µg per 100g (in corn) and 73 to 233 µg per 100 g (in wheat) and from 3.8 to 8.7 mg per 100 g (in corn) and 4.6 to 7.4 mg per 100g (in wheat) for iron. Finally the Brazilian population seems to be exposed to inadequate concentrations of folic acid and iron when consuming enriched corn flours and some wheat flours.
Recebido em 26/3/12; aceito em 4/6/12; publicado na web em 24/8/12 CHARACTERIZATION OF TEAS FROM Lippia gracilis Schauer GENOTYPES BY HPLC-DAD CHROMATOGRAPHIC PROFILE COMBINED WITH CHEMOMETRIC ANALYSES. In order to evaluate the effects of environmental factors on the content of secondary metabolites, the chemical profiles of infusions from leaves of seven genotypes of Lippia gracilis Schauer, sourced from two locations (Sergipe and Bahia state) and collected during different seasons: summer (with and without irrigation) and winter, were determined by HPLC-DAD. The fingerprint chromatograms were analyzed by PCA to evaluate similarities and differences among the samples. Results revealed differences among genotypes collected and cultivated under the same conditions, suggesting that three genotypes have greater resistance to drought conditions.
A fast and direct method for determination of milk adulteration by monitoring of calcium and sodium concentrations variations was described. Milk samples were furnished by a dairy company located at São Carlos (São Paulo State, Brazil) and spiked with tap-water, whey, hydrogen peroxide, synthetic urine, urea and synthetic milk in the ranged from 5% to 50% (v/v), expect for caustic soda. Caustic soda was added in the milk until establish the original pH. The milk samples were analyzed by using flame atomic absorption spectrometry (FAAS) and no acid digestion process was required. Results showed a significant decrease in the Na and Ca concentrations with addition of synthetic milk and tap-water, a nonlinear variation with addition of synthetic urine, whey and hydrogen peroxide and a largest increase in the Na concentration with addition of NaOH. Correlation between Na and Ca concentrations in pure and adulterated milk were evaluated by paired t-test at a 95% confidence level. Results showed that the method proposed is efficient to identify samples adulterated with tap-water, caustic soda, synthetics milk and urine.
Abstract:The proposition of simple and rapid methods for the identification of Cr (VI) levels in soil samples is desirable to guide remediation strategies. The aim of the present study was to develop a method for soils samples identification with Cr (VI) concentrations exceeding the values specified by international legislations. A soil sample was spiked with Cr (VI) concentrations varying from 0 to 20 mg kg -1 (total of 61 fortifications) and subsequently submitted to an alkaline extraction. The extracts were deposited in Petri plates and diphenylcarbazide 0.2 % (m v ) for pH adjustment were added. After color development, the plates were placed in a commercial scanner and images of their bottom part were acquired. The images were treated with computer programs to calculate the following color descriptors: R, G, B, H, S, V, r, g, b, L and an analysis by PCA (Principal Component Analysis) was performed. There was a good separation between values above and below the Italian legislation, which specifies a maximum value of 2.0 mg kg -1 for Cr (VI). Also were used the Cr (VI) values set by legislation of Canada and Sweden were used and, in general, the images allowed the identification of levels of Cr (VI) for these countries. Furthermore, through the visual analysis of PCA it is possible to state that digital images have potential to be used for the proposition of classification models.Keywords: Digital images; scanner; principal component analysis; hexavalent chromium; soils. ResumoA proposição de métodos simples e rápidos para a identificação dos níveis de Cr (VI) em amostras de solos é desejável para nortear estratégias de remediação. O presente trabalho teve como objetivo desenvolver um procedimento para a identificação de amostras de solos com concentrações de Cr (VI) superiores aos valores estabelecidos pelas legislações internacionais. Uma amostra de solo foi fortificada com concentrações de Cr (VI) que variaram de 0 a 20 mg kg -1 (total de 61 fortificações) e posteriormente submetidas a extração alcalina. Os extratos foram colocados em placas de Petri, aos quais se adicionou difenilcarbazida 0,2 % (m v -1 ) como reagente colorimétrico e H 2 SO 4 (5 mol L -1 ) para o ajuste do pH. Após o desenvolvimento da coloração, as placas foram posicionadas em um scanner comercial e obtidas imagens da parte inferior. As imagens foram tratadas com programas computacionais para cálculo dos seguintes descritores de cores (R, G, B, H, S, V, r, g, b e L) e, efetuou-se uma análise por ACP (Análise de componentes principais -Principal Component Analysis). Houve uma boa separação entre os valores acima e abaixo da legislação italiana, a qual define um valor máximo de 2,0 mg kg -1 para Cr (VI). Também foram utilizados os valores de Cr (VI) das legislações do Canadá e da Suécia e, em geral, as imagens permitiram a identificação dos níveis de Cr (VI) para estes países. Através da análise visual da ACP é possível afirmar que as imagens digitais são passíveis de uso para a proposição de modelos de classificação.
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A simple and sensitive method for simultaneously measuring dopamine (DA), ascorbic acid (AA), and uric acid (UA) using a poly(1-aminoanthracene) and carbon nanotubes nanocomposite electrode is presented. The experimental parameters for composite film synthesis as well as the variables related to simultaneous determination of DA, AA, and UA were optimized at the same time using fractional factorial and Doehlert designs. The use of carbon nanotubes and poly(1-aminoanthracene) in association with a cathodic pretreatment led to three well-defined oxidation peaks at potentials around À0.039, 0.180 and 0.351 V (vs. Ag/AgCl) for AA, DA, and UA, respectively. Using differential pulse voltammetry, calibration curves for AA, DA, and UA were obtained over the range of 0.16-3.12 10 À3 mol L , respectively. The proposed method was successfully applied to determine DA, AA, and UA in biological samples with good results.
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