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991.
Johan Mendoza Luis Cruz Victor de Freitas Fernando Pina Nuno Basílio 《Molecules (Basel, Switzerland)》2021,26(17)
Flavylium-based compounds in their acidic and cationic form bring color to aqueous solutions, while under slightly acidic or neutral conditions they commonly bring discoloration. Selective host-guest complexation between water-soluble p-sulfonatocalix[n]arenes (SCn) macrocycles and the flavylium cationic species can increase the stability of the colored form, expanding its domain over the pH scale. The association constants between SCn and the cationic (acid) and neutral basic forms of flavylium-based compounds were determined through UV-Vis host-guest titrations at different pH values. The affinity of the hosts for synthetic chromophore was found to be higher than for a natural anthocyanin (Oenin). The higher affinity of SC4 for the synthetic flavylium was confirmed by 1H NMR showing a preferential interaction of the flavylium phenyl ring with the host cavity. In contrast with its synthetic counterpart, the flavylium substitution pattern in the anthocyanin seems to limit the inclusion of the guest in the host’s binding pocket. In this case, the higher affinity was observed for the octamer (SC8) likely due to its larger cavity and higher number of negatively charged sulfonate groups. 相似文献
992.
F. G. Alvarenga R. Fracalossi R. C. Freitas S. V. B. Gonçalves 《General Relativity and Gravitation》2017,49(11):136
In this work the homogeneous and isotropic Universe of Friedmann–Robertson–Walker is studied in the presence of two fluids: stiff matter and radiation described by the Schutz’s formalism. We obtain to the classic case the behaviour of the scale factor of the universe. For the quantum case the wave packets are constructed and the wave function of the universe is found. 相似文献
993.
Pedro Freitas 《Journal of statistical physics》2017,167(6):1511-1518
We study the convergence of extrema of averages of eigenvalues of the Dirichlet Laplacian on domains in \(\mathbb {R}^{n}\) under both measure and surface measure restrictions. In the former case we prove that the sequence of averages to the power n / 2 is sub-additive and determine the first term in its asymptotics in the high-frequency limit. In the latter case, we show that the sequence of minimisers converges to the ball as the frequency goes to infinity. Similar results hold for Neumann boundary conditions. 相似文献
994.
An Artificial Immune System for Clustering Amino Acids in the Context of Protein Function Classification 总被引:1,自引:0,他引:1
A. Secker M. N. Davies A. A. Freitas J. Timmis E. Clark D. R. Flower 《Journal of Mathematical Modelling and Algorithms》2009,8(2):103-123
This paper addresses the classification task of data mining (a form of supervised learning) in the context of an important
bioinformatics problem, namely the prediction of protein functions. This problem is cast as a hierarchical classification
problem. The protein functions to be predicted correspond to classes that are arranged in a hierarchical structure (this takes
the form of a class tree). The main contribution of this paper is to propose a new Artificial Immune System that creates a
new representation for proteins, in order to maximize the predictive accuracy of a hierarchical classification algorithm applied
to the corresponding protein function prediction problem.
相似文献
995.
Erlin Sapei Petri Uusi-Kyyny Kari I. Keskinen Juha-Pekka Pokki Ville Alopaeus 《Fluid Phase Equilibria》2010
Isothermal vapor–liquid equilibrium (VLE) for tetrahydrothiophene + 2,2,4-trimethylpentane and tetrahydrothiophene + 2,4,4-trimethyl-1-pentene at 358.15 and 368.15 K were measured with a circulation still. All systems studied exhibit positive deviation from Raoult's law. No azeotropic behavior was found in all systems at the measured temperatures. The experimental results were correlated with the Wilson model and compared to COSMO-SAC predictive model. Analyses of liquid and vapor phase composition were determined with gas chromatography. All VLE measurements passed the three thermodynamic consistency tests used. The activity coefficients at infinite dilution are also presented. 相似文献
996.
Fábio G. Lepri Bernhard Welz Morgana B. Dessuy Maria Goreti R. Vale Denise Bohrer Margaretha T.C. de Loos-Vollebregt Mao Dong Huang Helmut Becker-Ross 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
The determination of phosphorus by graphite furnace atomic absorption spectrometry at the non-resonance line at 213.6 nm, and the capability of Zeeman-effect background correction (Z-BC) to deal with the fine-structured background absorption due to the PO molecule have been investigated in the presence of selected chemical modifiers. Two line source atomic absorption spectrometers, one with a longitudinally heated and the other with a transversely heated graphite tube atomizer have been used in this study, as well as two prototype high-resolution continuum source atomic absorption spectrometers, one of which had a longitudinally arranged magnet at the furnace. It has been found that Z-BC is capable correcting very well the background caused by the PO molecule, and also that of the NO molecule, which has been encountered when the Pd + Ca mixed modifier was used. Both spectra exhibited some Zeeman splitting, which, however, did not cause any artifacts or correction errors. The practical significance of this study is to confirm that accurate results can be obtained for the determination of phosphorus using Z-BC. 相似文献
997.
Robert B. McLaughlin Joseph R. Spiegel Jesse Selber Denise B. Gotsdiner Robert T. Sataloff 《Journal of voice》1999,13(2):240-245
Sarcoidosis can affect the larynx as a manifestation of systemic disease or as isolated laryngeal involvement. Classically, laryngeal involvement affects the supraglottis, and less commonly the subglottis, and true vocal fold involvement is rare. The clinical course is often highlighted by frequent exacerbations and remissions that, when associated with vague complaints and constitutional symptoms, are probably the greatest contributor to delayed presentation and diagnosis. We describe an unusual case of sarcoidosis that presented after a long and protracted clinical course as an isolated submucosal vocal fold mass requiring deep biopsy for diagnosis. A review of the literature with emphasis on diagnosis, appropriate airway management, and treatment is presented. 相似文献
998.
Gustavo Thalmer M. Silva Suma S. Thomas Cassio Pacheco Silva Jan C. Schlothauer Mauricio S. Baptista Adilson A. Freitas Cornelia Bohne Frank H. Quina 《Photochemistry and photobiology》2019,95(1):176-182
During the maturation of red wines, the anthocyanins of grapes are transformed into pyranoanthocyanins, which possess a pyranoflavylium cation as their basic chromophore. Photophysical properties of the singlet and triplet excited states of a series of synthetic pyranoflavylium cations were determined at room temperature in acetonitrile solution acidified with 0.10 mol dm?3 trifluoroacetic acid (TFA, to inhibit competitive excited state proton transfer) and at 77 K in a rigid TFA‐acidified isopropanol glass. In solution, the triplet states of these pyranoflavylium cations are efficiently quenched by molecular oxygen, resulting in sensitized formation of singlet oxygen, as confirmed by direct detection of the triplet‐state decay by laser flash photolysis and of singlet oxygen monomol emission in the near infrared. The strong visible light absorption, the relatively small singlet‐triplet energy differences, the excited state redox potentials and the reasonably long lifetimes of pyranoflavylium triplet states in the absence of molecular oxygen suggest that they might be useful as triplet sensitizers and/or as cationic redox initiators in polar aprotic solvents like acetonitrile. 相似文献
999.
Alex Fiori Silva Adriele Rodrigues dos Santos Daliah Alves Coelho Trevisan Edineia Bonin Camila Fabiano Freitas Andreia Farias Pereira Batista Noboru Hioka Manuel Simes Jane Martha Graton Mikcha 《Photochemistry and photobiology》2019,95(5):1230-1238
This study evaluated the rose bengal‐ and erythrosine‐mediated photoinactivation against Salmonella Typhimurium and Staphylococcus aureus planktonic and sessile cells using green LED as a light source. The free‐living or 2‐day‐old biofilm cells were treated with different concentrations of the photosensitizing agents and subjected to irradiation. Only 5 min photosensitization with rose bengal at 25 nmol L?1 and 75 μmol L?1 completely eliminated S. aureus and S. Typhimurium planktonic cells, respectively. Erythrosine at 500 nmol L?1 and 5 min of light exposure also reduced S. aureus planktonic cells to undetectable levels. Eradication of S. aureus biofilms was achieved when 500 μmol L?1 of erythrosine or 250 μmol L?1 of rose bengal was combined with 30 min of irradiation. Scanning electron microscopy allowed the observation of morphological changes in planktonic cells and disruption of the biofilm architecture after photodynamic treatment. The overall data demonstrate that rose bengal and erythrosine activated by green LED may be a targeted strategy for controlling foodborne pathogens in both planktonic and sessile states. 相似文献
1000.
William Gustavo Lima Flávio José dos Santos Adriana Cristina Soares Francisco A. Macías José M. G. Molinillo Jaqueline Maria Siqueira Ferreira 《合成通讯》2019,49(2):286-296
Benzoxazinoids (BXs), alkaloids frequently found in Gramineae species, are natural defensives that can potentially be exploited to the development of novel antimicrobial agents. Here, BXs analogs were synthesized from 2-nitrophenol (benzoxazinone series) and 3-hydroxy-2-nitropyridine (pyridoxazinone series) and tested against fungal and bacteria of medical interest. The starting materials were submitted to adequate nucleophilic substitution in order to functionalize of analogs, followed by a reductive cyclization catalyzed by palladium on carbon. Next, the biological assays showed that pyridoxazinone serie has a good antibacterial activity, especially against Enterococcus faecalis (Minimum inhibitory concentration—MIC: 7.8-15.6?μg.mL?1) and Acinetobacter baumannii (MIC 31.25-125?μg.mL?1). Antifungal activity, in turn, was related to compound 2e which showed a MIC of 62.5?μg.mL?1 against Candida albicans, Candida glabrata, and Candida tropicalis. All analogs complied with Lipinski's rules and were predicted to have a low toxicity. 相似文献