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71.
Costa M Areias F Castro M Brea J Loza MI Proença F 《Organic & biomolecular chemistry》2011,9(11):4242-4249
A one-pot procedure was developed for the synthesis of novel 3-[amino(methoxy)methylene]-2-oxo-3,4-dihydro-2H-chromen-4-yl)-3-cyanoacetamides and chromeno[3,4-c]pyridine-1-carbonitriles from the reaction of 2-oxo-2H-chromene-3-carbonitriles and cyanoacetamides. These chromene derivatives were identified as new scaffolds for adenosine receptors and the hits 3a, 3c, 5a, and 5b were found. 相似文献
72.
César Ricardo Teixeira Tarley Felipe Nascimento Andrade Fernanda Midori de Oliveira Marcela Zanetti Corazza Luiz Fernando Mendes de Azevedo Mariana Gava Segatelli 《Analytica chimica acta》2011,(2):145
A novel ion imprinted polyvinylimidazole-silica hybrid copolymer (IIHC) was synthesized and used as a selective solid sorbent for Pb2+ ions preconcentration using an on-line solid phase extraction (SPE) system coupled to TS-FF-AAS. The ionic hybrid sorbent was prepared using 1-vinylimidazole and 3-(trimethoxysilyl)propylmethacrylate as monomers, Pb2+ ions as template, tetraethoxysilane as reticulating agent and 2,2′-azobis-isobutyronitrile as initiator. The best on-line SPE conditions concerning sorption behavior, including sample pH (6.46), buffer concentration (9.0 mmol L−1), eluent (HNO3) concentration (0.5 mol L−1) and preconcentration flow rate (4.0 mL min−1), were optimized by means of full factorial design and Doehlert matrix. The analytical curve ranged from 2.5 to 65.0 μg L−1 (r = 0.999) with limit of detection of 0.75 μg L−1; the precision (repeatability) calculated as relative standard deviation (n = 10) was 5.0 and 3.6% for Pb2+ concentration of 10.0 and 60.0 μg L−1, respectively. From on-line breakthrough curve, column capacity was 3.5 mg g−1. Preconcentration factor (PF), consumptive index (CI) and concentration efficiency (CE) were 128.0, 0.16 mL and 25.6 min−1, respectively. The selective performance of the sorbent, based on relative selectivity coefficient, was compared to NIC (non imprinted copolymer) for the binary mixture Pb2+/Cd2+, Pb2+/Cu2+ and Pb2+/Zn2+. The results showed that ion imprinted polyvinylimidazole-silica hybrid polymer had higher selectivity for Pb2+ than NIC at 64.9, 16.0 and 8.8 folds. The developed method was successfully applied for highly sensitive and selective Pb2+ determination in different kinds of water samples, parenteral solutions and urine. Accuracy was also assessed by analyzing certified reference fish protein (DORM-3) and marine sediment (MESS-3 and PACS-2) with satisfactory results. 相似文献
73.
Juciane Prois Fortes Fernanda Wouters Franco Julia Baranzelli Gustavo Andrade Ugalde Cristiano Augusto Ballus Eliseu Rodrigues Mrcio Antnio Mazutti Sabrina Somacal Claudia Kaehler Sautter 《Molecules (Basel, Switzerland)》2023,28(1)
Consumers increasingly prefer and seek functional beverages, which, given their characteristics, provide important bioactive compounds that help prevent and treat chronic diseases. Mead is a traditional fermented alcoholic beverage made from honey solution. The aging process of mead with oak chips is innovative and bestows functional characteristics to this beverage. Thus, in this study, we sought to develop and characterize a novel functional beverage by combining the health benefits of honey with the traditional aging process of alcoholic beverages in wood. Phenolic compounds, flavonoids, and antioxidant capacity were analyzed in mead using oak chips at different toasting levels and aged for 360 days. LC-ESI-QTOF-MS/MS was used to analyze the chemical profile of different meads. Over time, the aging process with oak chips showed a higher total phenolic and flavonoid content and antioxidant capacity. Eighteen compounds belonging to the classes of organic acids, phenolic acids, flavonoids, and tannins were identified in meads after 360 days. Our findings revealed that the addition of oak chips during aging contributed to p-coumaric, ellagic, abscisic, and chlorogenic acids, and naringenin, vanillin, and tiliroside significantly impacted the functional quality of mead. 相似文献
74.
Amanda Rodrigues Pinto Costa Marcelly Muxfeldt Fernanda da Costa Santos Boechat Maria Cecília Bastos Vieira de Souza Jerson Lima Silva Marcela Cristina de Moraes Luciana Pereira Rangel Tuane Cristine Ramos Gonalves Vieira Pedro Netto Batalha 《Molecules (Basel, Switzerland)》2022,27(22)
Prion Diseases or Transmissible Spongiform Encephalopathies are neurodegenerative conditions associated with a long incubation period and progressive clinical evolution, leading to death. Their pathogenesis is characterized by conformational changes of the cellular prion protein—PrPC—in its infectious isoform—PrPSc—which can form polymeric aggregates that precipitate in brain tissues. Currently, there are no effective treatments for these diseases. The 2,5-diamino-1,4-benzoquinone structure is associated with an anti-prion profile and, considering the biodynamic properties associated with 4-quinolones, in this work, 6-amino-4-quinolones derivatives and their respective benzoquinone dimeric hybrids were synthesized and had their bioactive profile evaluated through their ability to prevent prion conversion. Two hybrids, namely, 2,5-dichloro-3,6-bis((3-carboxy-1-pentyl-4-quinolone-6-yl)amino)-1,4-benzoquinone (8e) and 2,5-dichloro-3,6-bis((1-benzyl-3-carboxy-4-quinolone-6-yl)amino)-1,4-benzoquinone (8f), stood out for their prion conversion inhibition ability, affecting the fibrillation process in both the kinetics—with a shortening of the lag phase—and thermodynamics and their ability to inhibit the formation of protein aggregates without significant cytotoxicity at ten micromolar. 相似文献
75.
Alexander A. Davydov Stefano Marcugini Fernanda Pambianco 《Designs, Codes and Cryptography》2009,50(3):359-372
An infinite family of complete (q
2 + q + 8)/2-caps is constructed in PG(3, q) where q is an odd prime ≡ 2 (mod 3), q ≥ 11. This yields a new lower bound on the second largest size of complete caps. A variant of our construction also produces
one of the two previously known complete 20-caps in PG(3, 5). The associated code weight distribution and other combinatorial properties of the new (q
2 + q + 8)/2-caps and the 20-cap in PG(3, 5) are investigated. The updated table of the known sizes of the complete caps in PG(3, q) is given. As a byproduct, we have found that the unique complete 14-arc in PG(2, 17) contains 10 points on a conic. Actually, this shows that an earlier general result dating back to the Seventies fails
for q = 17.
相似文献
76.
Roberto Kawakami Harrop Galvão Sófacles Figueredo Carreiro Soares Marcelo Nascimento Martins Maria Fernanda Pimentel Mário César Ugulino Araújo 《Analytica chimica acta》2015
This paper proposes a new method for calibration transfer, which was specifically designed to work with isolated variables, rather than the full spectrum or spectral windows. For this purpose, a univariate procedure is initially employed to correct the spectral measurements of the secondary instrument, given a set of transfer samples. A robust regression technique is then used to obtain a model with low sensitivity with respect to the univariate correction residuals. The proposed method is employed in two case studies involving near infrared spectrometric determination of specific mass, research octane number and naphthenes in gasoline, and moisture and oil in corn. In both cases, better calibration transfer results were obtained in comparison with piecewise direct standardization (PDS). The proposed method should be of a particular value for use with application-targeted instruments that monitor only a small set of spectral variables. 相似文献
77.
This paper extends prior work by the authors on solving nonlinear least squares unconstrained problems using a factorized
quasi-Newton technique. With this aim we use a primal-dual interior-point algorithm for nonconvex nonlinear programming. The
factorized quasi-Newton technique is now applied to the Hessian of the Lagrangian function for the transformed problem which
is based on a logarithmic barrier formulation. We emphasize the importance of establishing and maintaining symmetric quasi-definiteness
of the reduced KKT system. The algorithm then tries to choose a step size that reduces a merit function, and to select a penalty
parameter that ensures descent directions along the iterative process. Computational results are included for a variety of
least squares constrained problems and preliminary numerical testing indicates that the algorithm is robust and efficient
in practice. 相似文献
78.
79.
We study the well-posedness of a stochastic differential equation on the two dimensional torus , driven by an infinite dimensional Wiener process with drift in the Sobolev space . The solution corresponds to a stochastic Lagrangian flow in the sense of DiPerna Lions. By taking into account that the motion of a viscous incompressible fluid on the torus can be described through a suitable stochastic differential equation of the previous type, we study the inviscid limit. By establishing a large deviations principle, we show that, as the viscosity goes to zero, the Lagrangian stochastic Navier–Stokes flow approaches the Euler deterministic Lagrangian flow with an exponential rate function. 相似文献
80.
Fernanda Botelho 《Linear algebra and its applications》2010,432(12):3337-3342
In this paper we establish algebraic reflexivity properties of subsets of bounded linear operators acting on spaces of vector valued Lipschitz functions. We also derive a representation for the generalized bi-circular projections on these spaces. 相似文献