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排序方式: 共有58条查询结果,搜索用时 15 毫秒
41.
Sara Canas Florina Danalache Oflia Anjos Tiago A. Fernandes Ilda Caldeira Ndia Santos Laurent Fargeton Benjamin Boissier Sofia Catarino 《Molecules (Basel, Switzerland)》2020,25(22)
Alternative technologies for a more sustainable wine spirits’ ageing have been studied but a lack of knowledge on the effect of oxygenation level remains. This work examined the behaviour of low molecular weight compounds, iron and copper of a wine spirit aged in 50 L demijohns with chestnut wood staves combined with three levels of micro-oxygenation or nitrogen. Compounds and mineral elements were quantified by HPLC and FAAS, respectively, in samples collected at 8, 21, 60, 180, 270 and 365 days of ageing. Results showed that most of the compounds underwent significant changes in their content over time and behave differently depending on the wine spirit’s oxygenation level: higher contents of gallic acid, syringic acid and vanillin were associated with lower micro-oxygenation level while higher contents of ellagic acid, syringaldehyde, coniferaldehyde and sinapaldehyde resulted from higher one; lowest contents of these compounds were found in the nitrogen modality. Weak correlation between copper and the studied compounds was evidenced whereas closer relationship between iron, vanillin, gallic, syringic and ellagic acids at end of ageing was observed. This study provides innovative information on the role of oxygen in wine spirit’s ageing, and on chestnut wood effect on wine spirit’s mineral composition. 相似文献
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Rose-Marie Belardi Jonathan Deseure Márcia Caldeira Brant Tulio Matencio Rosana Zacarias Domingues 《Ionics》2009,15(2):227-232
The effect of cathodic activation of sprayed La0.8Sr0.2MnO3 (LSM) films has been studied by electrochemical spectroscopy impedance (EIS). LSM powder was prepared by a citrate route
and X-ray diffraction analyses show a complete LSM crystallization without La2O3 or La(OH)3 as side products. Porosity and grain size estimated from scanning electronic microscopy gave values of 33% and 100 nm, respectively.
EIS measurement was performed on a Pt/yttria-stabilized zirconia/LSM cell before and after a cathodic current load (300 mA/cm2) on LSM electrode. The relaxation process, which is time-dependent, has been investigated. A drastic decrease of the electrode
resistance was noticed just after applying the cathodic current, but after 9 h at optimized valence configuration in air at
850 °C, the recorded polarization resistance gradually enhanced until it almost reached the initial value. The resulting diagrams
have been fitted using a Gerischer associated with a resistor and constant phase elements. This simple method has permitted
us to observe that only the electrode interfaces are modified by a cathodic activation and the microstructure remains nearly
constant. 相似文献
45.
Caldeira Leila Rodrigues Lima Josefa Abucáter Santos Flávio Alves Lana Mary Ane Gonçalves dos Santos Rossi Ribeiro Ana Cláudia de Oliveira Elcio Cruz 《Accreditation and quality assurance》2017,22(2):91-96
Accreditation and Quality Assurance - Ractopamine is used as an animal feed additive, but its adverse effects led to the necessity of the current monitoring programs of ractopamine residues in food... 相似文献
46.
The construction of the quantum-mechanical Hamiltonian by canonical quantization is examined. The results are used to enlighten examples taken from slow nuclear collective motion. Hamiltonians, obtained by a thoroughly quantal method (generator-coordinate method) and by the canonical quantization of the semiclassical Hamiltonian, are compared. The resulting simplicity in the physics of a system constrained to lie in a curved space by the introduction of local Riemannian coordinates is emphasized. In conclusion, a parallel is established between the result for various coordinates and a proposed procedure for quantizing the semiclassical Hamiltonian for a single coordinate.Partially supported by Fundação Calouste Gulbenkian, Lisboa. 相似文献
47.
S. M.G. Caldeira T. C. Petit Lobão R. F.S. Andrade A. Neme J. G.V. Miranda 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,49(4):523-529
Complex network theory is used to investigate the
structure of meaningful concepts in written texts of individual
authors. Networks have been constructed after a two phase
filtering, where words with less meaning contents are eliminated
and all remaining words are set to their canonical form, without
any number, gender or time flexion. Each sentence in the text is
added to the network as a clique. A large number of written texts
have been scrutinised, and it is found that texts have small-world
as well as scale-free structures. The growth process of these
networks has also been investigated, and a universal evolution of
network quantifiers have been found among the set of texts written
by distinct authors. Further analyses, based on shuffling
procedures taken either on the texts or on the constructed
networks, provide hints on the role played by the word frequency
and sentence length distributions to the network structure. 相似文献
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Raquel Eustquio Joo P. Prates Ramalho Ana T. Caldeira Antnio Pereira 《Molecules (Basel, Switzerland)》2022,27(5)
Important scientific areas, such as cellular biology, medicine, pharmacy, and environmental sciences, are dependent on very sensitive analytical techniques to track and detect biomolecules. In this work, we develop a simple, low-cost and effective synthetic strategy to produce new red-shifted 4-styrylcoumarin derivatives as promising inexpensive fluorescent labels for biomolecules. The extension of the delocalized π-electron system results in bathochromic shifts in these new coumarin derivatives, which also present large Stokes shifts. In addition, density functional theory and time-dependent density functional theory calculations helped to rationalize the photophysical properties observed by the experimental results. 相似文献
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