2,299 research outputs found

    Phosphorus adsorption by clay fractions in the presence of fulvic acid

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    Os ácidos orgânicos podem ser adsorvidos aos coloides do solo, favorecendo maior disponibilidade de P às plantas. Por meio de isotermas, avaliou-se a influência de ácido fúlvico (AF) sobre a adsorção de P na fração argila de dois Latossolos Vermelhos (LVdf e LVd), caulinita natural pouco cristalizada (KGa2), goethita (Gt) e hematita (Hm) sintéticas. As isotermas de adsorção de P ajustadas pelo modelo de Langmuir na presença de AF foram adequadas somente para a região de baixa concentração de P. De maneira geral, a presença de AF incubado nas frações argila estudadas foi capaz de reduzir a adsorção de P. Na fração argila do LVdf, a adsorção de P em baixas e altas concentrações desse nutriente teve pequena influência da sequência de incubação de P com AF, enquanto para a fração argila do LVd as sequências de incubação com P e AF influenciaram a adsorção de P. A redução da adsorção de P sobre a fração argila da KGa2 em baixas concentrações de P nas isotermas não dependeu da sequência de incubação de P e AF, e sim da presença do AF. Na região de altas concentrações de P, a sequência de incubação de P e AF influenciou a adsorção desse elemento. A adsorção de P sobre Gt foi dependente da sequência de incubação com AF, e a incubação prévia do AF promoveu redução da adsorção de P. A sequência de incubação do P e AF na Hm influenciou a adsorção de P quando em baixas e altas concentrações nas isotermas. Os menores valores de adsorção de P ocorreram com a incubação de P juntamente ao AF ou incubação de AF precedida da do P

    Using Neural Data to Test a Theory of Investor Behavior: An Application to Realization Utility

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    We conduct a study in which subjects trade stocks in an experimental market while we measure their brain activity using functional magnetic resonance imaging. All of the subjects trade in a suboptimal way. We use the neural data to test a "realization utility" explanation for their behavior. We find that activity in two areas of the brain that are important for economic decision-making exhibit activity consistent with the predictions of realization utility. These results provide support for the realization utility model. More generally, they demonstrate that neural data can be helpful in testing models of investor behavior

    An Ascorbate Bluetooth© Analyzer for Quality Control of Fresh-Cut Parsley Supply Chain

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    This work provides companies in the fresh-cut produce sector with an Ascorbate Bluetooth© Analyzer (ABA), a screen-printed sensor-based device for ascorbic acid (AA) detection, for quality control all along the supply chain. The amperometric detection of AA on fresh and fresh-cut parsley, under correct and incorrect storage temperature, allowed us to investigate the kinetics of AA decay in response to oxidative stress. The role of ascorbate oxidase (AOx) and ascorbate peroxidase (APx) was studied. ABA was used in situ by unskilled personnel. Treatments influenced AA decay kinetics, which were linear in fresh parsley, and non-linear in fresh-cut. Two hours at 28◦C immediately after chopping, the resilience of the fresh-cut parsley was reduced, even though the cold chain was restored. Two hours at −2◦C caused a rapid loss of AA until its complete decay after 72 h. Significant differences between treatments were observed in both the expression and activity of AOx and APx. ABA registered sudden changes of parsley AA following unpredicted variations of temperature during processing or transport. It was useful to remedy the effects of unexpected flaws in the cold chain, which can be proposed for quality preservation of different fresh-cut produce

    An Integrated Caco-2TC7cells/biosensors Device for the Real Time Monitoring of Intestinal Glucose and Polyphenols Absorption and Hypoglycemic Effect of Phytochemicals

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    Abstract An integrated device, for real-time monitoring of glucose and phenols absorption, that consists of a sensors/biosensors system (SB) and a Caco-2TC7 human intestinal cell culture, is shown here. The SB was made of a glucose oxidase-based biosensor, a sentinel platinum sensor, a laccase/tyrosinase-based biosensor and a sentinel carbon sensor located in the basolateral compartment (BC) of a cell culture plate. This system was able to monitor the glucose absorption and the hypoglycemic effect induced by different polyphenols and could be proposed to provide an effective strategy to manage postprandial hyperglycemia with natural compounds

    Characterisation of Diospyros kaki (persimmon) vinegars produced with different microorganisms

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    The aim of this work was to evaluate the characteristics of nine kaki vinegars produced using different yeasts and bacteria traditionally involved in wine production, and to evaluate their acidity, density, total phenolic content, and antioxidant activity. Furthermore, the study characterized the volatile fingerprinting by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and by two-dimensional gas chromatography coupled to mass spectrometry (GCxGC-TOF-MS). Finally, individual carotenoids were characterized using high performance liquid chromatography (HPLC). More than a thousand distinguishing molecules were found. It was discovered that vinegars fermented with S. cerevisiae produced a larger number of volatile chemicals. Among the three vinegars produced with this strain, the one fermented with Acetobacter_vino seemed to have a more elaborate flavour profile than all the other samples. The vinegar produced utilizing the mixture of T. delbruekii and Acetobacter was the only kind to have a high concentration of carotenoids
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