1,119 research outputs found

    Solution and Asymptotic Behavior for a Nonlocal Coupled System of Reaction-Diffusion

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    This paper concerns with existence, uniqueness and asymptotic behavior of the solutions for a nonlocal coupled system of reaction-diffusion. We prove the existence and uniqueness of weak solutions by the Faedo-Galerkin method and exponential decay of solutions by the classic energy method. We improve the results obtained by Chipot-Lovato and Menezes for coupled systems. A numerical scheme is presented

    Advances in chemometric control of commercial diesel adulteration by kerosene using IR spectroscopy

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    Adulteration is a recurrent issue found in fuel screening. Commercial diesel contamination by kerosene is highly difficult to be detected via physicochemical methods applied in market. Although the contamination may affect diesel quality and storage stability, there is a lack of efficient methodologies for this evaluation. This paper assessed the use of IR spectroscopies (MIR and NIR) coupled with partial least squares (PLS) regression, support vector machine regression (SVR), and multivariate curve resolution with alternating least squares (MCR-ALS) calibration models for quantifying and identifying the presence of kerosene adulterant in commercial diesel. Moreover, principal component analysis (PCA), successive projections algorithm (SPA), and genetic algorithm (GA) tools coupled to linear discriminant analysis were used to observe the degradation behavior of 60 samples of pure and kerosene-added diesel fuel in different concentrations over 60 days of storage. Physicochemical properties of commercial diesel with 15% kerosene remained within conformity with Brazilian screening specifications; in addition, specified tests were not able to identify changes in the blends’ performance over time. By using multivariate classification, the samples of pure and contaminated fuel were accurately classified by aging level into two well-defined groups, and some spectral features related to fuel degradation products were detected. PLS and SVR were accurate to quantify kerosene in the 2.5–40% (v/v) range, reaching RMSEC < 2.59% and RMSEP < 5.56%, with high correlation between real and predicted concentrations. MCR-ALS with correlation constraint was able to identify and recover the spectral profile of commercial diesel and kerosene adulterant from the IR spectra of contaminated blends

    Vp/Vs ratios in the Parnaíba Basin from joint active-passive seismic analysis – Implications for continental amalgamation and basin formation

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    Acknowledgements The authors thank Jordi Julià and two anonymous reviewers for valuable comments on an earlier version of the manuscript. Thanks to the PBAP program for the availability of WARR, DSR and teleseismic three-component data (Project 5547: BP ENERGY/FUB/FINATEC— PARNAÍBA BASIN REFRACTION EXPERIMENT). RAF thanks CNPq and INCT Estudos Tectônicos (CNPq, CAPES, FAP-DF) for research fellowship and funds. *The data that support the findings of this study may be available from the authors upon reasonable request.Peer reviewedPublisher PD

    Digestible lysine effects on gene expression by Japanese quails in the pre-laying phase

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    This study aimed to determine the effects of digestible lysine levels in the diets of Japanese quail (Coturnix coturnix japonica) on performance, blood parameters and the expression of insulin-like growth factor I, and growth hormone receptor (GHR), apolipoprotein A-I (APOA-I), acetyl-CoA-carboxylase (ACC), and fatty acid synthase (FAS) genes. A total of 288 seven-day-old female Japanese quails were randomly assigned to one of three diets that contained 0.8%, 1.10%, or 1.40% digestible lysine. The birds were slaughtered at 42 days old, and relative gene expression was evaluated in the liver by qRT-PCR using the 2-ΔCT method. Lysine supplementation had no effect on weight gain and feed conversion. Abdominal fat was lower in birds supplemented with 0.8% digestible lysine than those supplemented with 1.10% and 1.40%. Increased total cholesterol and triglycerides were elevated in quails that received supplementation of 1.10% digestible lysine compared with the other diets. High density lipoproteins were decreased in birds that received 0.8% digestible lysine. Quails fed with 1.40% digestible lysine had greater expression of GHR and APOA-I than quails fed diets with 0.8 and 1.10% (P &lt;0.05). The greatest expressions of ACC and FAS were observed in the liver of quails fed with 0.8% digestible lysine. The current results suggest that lysine supplementation in the pre-laying phase allows birds to deposit muscle mass to reach the optimal conformation and body fatness that provides an energetic reserve for the productive phase by modulating the expression of genes related to growth and lipid metabolism. Keywords: Coturnix coturnix japonica, growth, growth hormone, lipid synthesis, lipid metabolis

    Nematodes Affecting Potato and Sustainable Practices for Their Management

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    Plant-parasitic nematodes are a significant factor limiting potato production and tuber quality in several regions where potato is produced. Overall, parasitic nematodes alone cause an estimated annual crop loss of $ 78 billion worldwide and an average crop yield loss of 10–15%. As a result, sustainable food production and food security are directly impacted by pests and diseases. Degrading land use with monocultures and unsustainable cropping practices have intensified problems associated with plant pathogens. Proper identification of nematode species and isolates is crucial to choose effective and sustainable management strategies for nematode infection. Several nematode species have been reported associated with potato. Among those, the potato cyst nematodes Globodera rostochiensis and G. pallida, the root-knot nematode Meloidogyne spp., the root lesion nematode Pratylenchus spp., the potato rot nematode Ditylenchus destructor and the false root-knot nematode Nacobbus aberrans are major species limiting potato yield and leading to poor tuber quality. Here, we report a literature review on the biology, symptoms, damage and control methods used for these nematode species

    Chemical assays and chromatographíc analysis from tannins contents in Gomidesia palustris (DC.) Kausel (Myrtaceae)

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    Gomidesia palustris (DC.) Kausel é uma planta pertencente à família Myrtaceae, de ampla ocorrência na região sul do Brasil, conhecida popularmente como "pitangueira-do-mato" ou "guamirim". Não tendo sido encontradas referências a estudos anteriores, as folhas e os frutos foram analisados quanto à composição química. Os testes preliminares indicaram teor elevado de taninos. Os ensaios químicos e a análise cromatográfica indicaram a presença de taninos hidrolisáveis, com a predominância de taninos elágicos. Para a quantificação desse tipo de composto foi utilizado, com algumas adaptações, o método de hemoanálise com doseamento espectrofotométrico da hemoglobina residual, após precipitação dos taninos, sendo encontrado um valor médio de 12,71% de compostos tanantes nas folhas. Através de processos cromatográficos, foram isolados o ácido elágico e o ácido gálico.Gomidesia palustris (DC.) Kausel (Myrtaceae) is an evergreen tree widely spread in southern Brazil and surrounding regions, commonly known as "pitangueira-do-mato" or "guamirim". There is no former reference to the chemical studies of this species. Preliminary tests and further chemical assays and chromatographic analysís detected high tannins contents in the leaves, chiefly hydrolisable tannins with predominance of ellagitannins. Ellagic acid and gallic acid were isolated by chromatographic methods. The content of the tannins was determined by spectrophotometric haemoanalysis after a partial precipitation with tannins (modified Bate-Smith's method). A mean content of 12,71% was found in the leaves
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