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51.
Andre L. M. Freitas Dereck N. F. Muche Edson R. Leite Flavio L. Souza 《Journal of the American Ceramic Society》2020,103(12):6833-6846
This work addresses the role of different modifiers on the overall photocurrent response, which allowed a dual material insertion, increasing the charge separation without compromise the surface catalysis. Sn-addition onto nanoceramic hematite photoelectrodes clearly increased flat band potential, promoting a good charge separation, and shifting the onset to a higher potential, attributed to the surface-trapping state created by this modification. Notoriously, Sn-hematite photoelectrodes loaded with NiFeOx exhibited the highest photocurrent density, suggesting a partially recovered surface-trapping states created during the electrode designing. The well-known cocatalyst acted in the overall photoelectrocatalytic response with no significant effect on the turn-on voltage, in other words, with minor effect related to catalytic efficiency. The dual modification contributes to understand the role of different modifiers allowing to satisfactorily improve charge separation while maintaining the conductivity attributed to IV-group ions. 相似文献
52.
Rosane Lopes Crizel Jessica Fernanda Hoffmann Giovana Paula Zandon Paula Mendona Shild Lobo Rogerio Oliveira Jorge Fabio Clasen Chaves 《European Journal of Lipid Science and Technology》2020,122(4)
Six olive oils extracted from the cultivars Arbequina, Arbosana, Coratina, Frantoio, Koroneiki, and Picual from 2017 and 2018 harvests, cultivated in Pinheiro Machado, Rio Grande do Sul, Brazil, are evaluated for standard oil composition parameters and bioactive constituents (pigments, tocopherols, and phenolic compounds). Multivariate principal component analysis (PCA) and univariate ANOVA and Fisher's LSD test are used to verify the effect of cultivar and harvest year on oil composition. Olive oil composition met extra virgin olive oil (EVOO) standard parameters and is influenced by both cultivar and harvest year. EVOO produced in 2018 has greater chlorophyll, caffeic acid, ligstroside aglycone, hydroxyoleuropein aglycone, syringic acid, and hydroxytyrosol acetate contents than the EVOOs from 2017. Linoleic acid, ferulic acid, ligstroside aglycone, and hydroxytyrosol acetate are the variables whose contents most contributed to the differentiation of oils by cultivar in both harvest years. Chemical characterization analyses allow for the differentiation of oil composition based on harvest year and cultivar. Metabolic quality data obtained here support the establishment of a local EVOO profile and the compounds that most contributed to treatment differentiation may serve as markers that can be utilized in determining origin, cultivar, and harvest year. Practical Applications: Olive production in Brazil is recent and is based on European cultivars which have not been bred for the local environmental conditions. Therefore, the measurement of olive oil metabolic quality will determine cultivar adaptability to local edaphoclimatic conditions as well as assist in the establishment of a standard of identity for the product and promote the development of its market. Olive oil produced in Southern Brazil shows high quality, and is especially rich in phenolic compounds. Although harvest year influences oil composition, oil from both harvests meet EVOO standards and cultivar specific metabolic markers are observed. This study provides the foundation for olive producers in Southern Brazil to seek authentication of the geographical origin of olive oil. 相似文献
53.
Leonardo Queiroz de Souza Ana Dolores Santiago de Freitas Everardo Valadares de Sá Barretto Sampaio Patrícia Maia Moura R?mulo Sim?es Cezar Menezes 《Nutrient Cycling in Agroecosystems》2012,94(2-3):171-179
Despite the recognized importance of the process, estimates of the amount of nitrogen fixed by biological symbiosis in tropical dry forests are almost nonexistent. We estimated the nitrogen fixed annually by the leaves of trees and shrubs at sites regenerating for 16 and 38?years and in an old-growth dry forest using 15N abundance methodology. The total leaf biomass (1,824?C3,036?kg?ha?1) and nitrogen contents (62?C90?kg?ha?1) did not differ among the areas. In all of the areas, most of the leaf biomass belonged to legume plants, but the proportion of the N2-fixing legumes decreased with increasing regeneration time. In the 16-year regenerating area, almost all of the N was in the leaves of the N-fixing Mimosa tenuiflora plants, but fixation was absent or very low as it was in the N-fixing species present in the 38-year regenerating area. In the old-growth Caatinga, all of the N-fixing species (M. tenuiflora, Piptadenia stipulacea and Anadenanthera colubrina) had large proportions (47?C62?%) of their N derived from atmospheric N2, but the amount of fixed N (6?kg?ha?1) was a small proportion of the total leaf N because these plant species were a small part of the vegetation. The total input of biologically fixed N to the old-growth forest was similar in magnitude to an estimate made for a humid tropical forest in Amazonia. 相似文献
54.
Renan C. Chisté Marisa Freitas Adriana Z. Mercadante Eduarda Fernandes 《Journal of food science》2014,79(9):H1841-H1847
β‐Carotene, zeaxanthin, lutein, β‐cryptoxanthin, and lycopene are liposoluble pigments widely distributed in vegetables and fruits and, after ingestion, these compounds are usually detected in human blood plasma. In this study, we evaluated their potential to inhibit hemolysis of human erythrocytes, as mediated by the toxicity of peroxyl radicals (ROO?). Thus, 2,2′‐azobis (2‐methylpropionamidine) dihydrochloride (AAPH) was used as ROO? generator and the hemolysis assay was carried out in experimental conditions optimized by response surface methodology, and successfully adapted to microplate assay. The optimized conditions were verified at 30 × 106 cells/mL, 17 mM of AAPH for 3 h, at which 48 ± 5% of hemolysis was achieved in freshly isolated erythrocytes. Among the tested carotenoids, lycopene (IC50 = 0.24 ± 0.05 μM) was the most efficient to prevent the hemolysis, followed by β‐carotene (0.32 ± 0.02 μM), lutein (0.38 ± 0.02 μM), and zeaxanthin (0.43 ± 0.02 μM). These carotenoids were at least 5 times more effective than quercetin, trolox, and ascorbic acid (positive controls). β‐Cryptoxanthin did not present any erythroprotective effect, but rather induced a hemolytic effect at the highest tested concentration (3 μM). These results suggest that selected carotenoids may have potential to act as important erythroprotective agents by preventing ROO?‐induced toxicity in human erythrocytes. 相似文献
55.
Optimization of alcohol‐free beer production by lager and cachaça yeast strains using response surface methodology
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Cláudia Puerari Jan Strejc Angélica C. Souza Marcel Karabín Rosane F. Schwan Tomáš Brányik 《Journal of the Institute of Brewing》2016,122(1):69-75
Alcohol‐free beers (AFBs) are an attractive segment of the beer market both for the brewing industry and for consumers. While AFBs produced by arrested/limited fermentation often suffer from a lack of volatile compounds, beer flavour can be improved by yeast selection and optimization of fermentation conditions. The yeast selection strategy was demonstrated by comparing traditional lager yeast with selected cachaça yeast strains. Correspondingly, response surface methodology was used to enhance the formation of the flavour‐active volatile compounds by optimization of the fermentation conditions (original wort extract, fermentation temperature, pitching rate). Statistical analysis of the experimental data revealed the relative significance of process variables and their interactions. The developed quadratic model describing the responses of total esters and higher alcohols to changes in process variables was used to predict the ideal fermentation conditions in terms of flavour formation. The predicted conditions were experimentally verified and alternative strategies of AFB production are suggested. Copyright © 2016 The Institute of Brewing & Distilling 相似文献
56.
Bacteria, yeasts and filamentous fungi were isolated during natural coffee processing. Bacteria were isolated in greater numbers at the beginning of the fermentation, when the moisture of the coffee beans was around 68%. Gram-positive bacteria represented 85.5% of all bacteria isolated, and Bacillus was the predominant genus (51%). Gram-negative species of the genera Serratia, Enterobacter and Acinetobacter were also found. Approximately 22% of 940 randomly chosen isolates of microorganisms were yeasts. Debaryomyces (27%), Pichia (18.9%) and Candida (8.0%) were the most commonly found genera, and these three genera tended to appear more often as the fruit was fermented and dried. Aspergillus was the most abundant genus besides Penicillium, Fusarium and Cladosporium, with 42.6% of the total fungi isolates. The genera and species identified included members known to have pectinase and cellulase activities. Of the 10 organic acids analyzed and quantified in coffee beans, acetic and lactic acids may have been generated by microbial activity. Butyric acid was not detected in any sample. 相似文献
57.
Antônio Alisson Alencar Freitas Fernando Lessa Tofoli Edilson Mineiro Sá Junior Sergio Daher Fernando Luiz Marcelo Antunes 《International Journal of Electronics》2016,103(5):898-912
A high voltage step-up nonisolated DC–DC converter based on coupled inductors suitable to photovoltaic (PV) systems applications is proposed in this paper. Considering that numerous approaches exist to extend the voltage conversion ratio of DC–DC converters that do not use transformers, a detailed comparison is also presented among the proposed converter and other popular topologies such as the conventional boost converter and the quadratic boost converter. The qualitative analysis of the coupled-inductor-based topology is developed so that a design procedure can be obtained, from which an experimental prototype is implemented to validate the theoretical assumptions. 相似文献
58.
J. Azevedo I. Fernandes P. Lopes I. Roseira M. Cabral N. Mateus V. Freitas 《European Food Research and Technology》2014,239(6):951-960
Considering the enological interest of cork, this study aimed to identify and quantify the phenolic compounds able to migrate from different classes (natural cork stoppers “Flor” and “Third” quality and microagglomerate cork stopper) of cork stoppers into bottled wine model solutions. Another aim was to evaluate some antioxidant and biological features of cork phenolics that migrated into the wine model solutions. The main phenolic acids and aldehydes detected were as follows: gallic and protocatechuic acid detected both around 3.5 mg/L and vanillin and protocatechuic aldehyde detected around 2.5 and 1.5 mg/L after 27 months of bottling, respectively. Trace amounts of more complex polyphenols, namely hydrolysable tannins (castalagin/vescalagin and mongolicain A/B), were also detected. Two antioxidant features of the wine model solutions bottled with different wine cork stoppers were studied, namely the antiradical capacity and the reducing capacity, being the natural cork stoppers the ones with the higher activities. The intestinal absorption of the compounds in each wine model solution after 27 months in bottled was evaluated. The simpler phenolic compounds were able to cross Caco-2 cell model. The antiproliferative activity of the same wine model solutions was also evaluated against gastric and breast cancer cells. All samples were active against the two cell lines, which highlight the possible health outcomes of wine sealed with cork stoppers. 相似文献
59.
Samer El Oukaili Michael Schwan Stefan Federlein 《Electrical Engineering (Archiv fur Elektrotechnik)》2009,90(8):569-576
Liberalization has increased economic pressure on network operators, urging them to compromise between cost savings and supply
reliability. In this context, the detailed and quantitative evaluation of supply reliability is gaining ever more importance—especially
its application in comprehensive asset management methods. However, the large number of components especially in medium voltage
distribution networks leads to high computation times for such probabilistic reliability analyses. A recent research project
deals with investigations into a forecast of system supply reliability performance following a simplified methodology. Developing
different forecasting methods, also several aspects of significant importance for the calculation of supply reliability in
MV distribution systems in general were identified. Especially for electrical networks of a certain size, the overlapping
of independent single failures, as well as complex failures play an important role. This paper presents the background of
the reliability centered asset management approach as well as the general idea and different approaches to the forecasting
methods in theory briefly. Following, the application on two different example networks demonstrates the approaches and the
achieved results, and reveals also the relevance of overlapping and complex failures in these results. 相似文献
60.
The aim of the present work was to identify the extractable phenolic compounds present in cork from Quercus suber L. The structures of thirty three compounds were tentatively identified by liquid chromatography coupled to electrospray ionisation mass spectrometry (HPLC–DAD/ESI–MS). The majority of those compounds were gallic acid derivatives, in the form of either galloyl esters of glucose (gallotannins), combinations of galloyl and hexahydroxydiphenoyl esters of glucose (ellagitannins), dehydrated tergallic-C-glucosides or ellagic acid derivatives. Others were found to correspond to low molecular weight phenolic compounds, like acids and aldehydes. Mongolicain, a flavanoellagitannin in which hydrolysable tannin and flavan-3-ol moieties are connected through a carbon–carbon linkage, was also detected in cork from Q. suber L. The results illustrate the rich array of phenolic compounds present in cork. 相似文献