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581.
Jussara Vieira da Silva Delton Martins Pimentel Dênio Emanuel Pires Souto Rita de Cássia Silva Luz Flavio Santos Damos 《Journal of Solid State Electrochemistry》2013,17(11):2795-2804
Polyaniline/O,O′-bis (2-aminoethyl) polyethylene glycol-functionalized multiwalled carbon nanotube (PANI/PEG–MWCNT) composite-modified electrode was successfully prepared by electropolymerization. The ionic transport in PANI/PEG–MWCNT film and its effects on the composite performance are presented. Both protonic and anionic participation in the charge compensation processes were calculated and they indicated that the presence of the PEG–MWCNT in the PANI film suppress the anionic transportation and improve the composite ability in fixing horseradish peroxidase enzyme. Finally, the adsorption between the negatively charged PANI/PEG–MWCNT nanocomposite and the positively charged Horseradish peroxidase resulted in a high sensitivity (1.01 μA L cm?2 μmol?1) to hydrogen peroxide. This sensor exhibited a good reproducibility and stability at an applied potential of ?100 mV vs Ag/AgCl. 相似文献
582.
A general synthetic strategy, based on a convergent approach, allowed us to prepare a series of luminescent unsymmetrical bent‐core compounds (2,5‐(disubstituted)‐1,3,4‐oxadiazole derivatives), via the Sonogashira crosscoupling reaction, all possessing a similar hockey stick shape. Their mesophases were characterized using polarizing optical microscopy and differential scanning calorimetry. The observed LC phases possess the classical textures of calamitic liquid crystals. Fluorescence in solution for these compounds exhibits strong blue emission (λmax em. = 390–460 nm) with good quantum yields (50–85%). 相似文献
583.
HR‐MAS NMR metabolomics of ‘Swingle’ citrumelo rootstock genetically modified to overproduce proline
Caroline S. de Oliveira Eduardo F. Carlos Luiz G. E. Vieira Luciano M. Lião Glaucia B. Alcantara 《Magnetic resonance in chemistry : MRC》2014,52(8):422-429
The accumulation of proline is a typical physiological response to abiotic stresses in higher plants. ‘Swingle’ citrumelo, an important rootstock for citrus production, has been modified with a mutated Δ1‐pyrroline‐5‐carboxylate synthetase gene (VaP5CSF129A) linked to the cauliflower mosaic virus 35S promoter to induce the overproduction of free proline. This paper presents a comparative metabolomic study of nontransgenic versus transgenic ‘Swingle’ citrumelo plants with high endogenous proline. 1H high‐resolution magic angle spinning nuclear magnetic resonance spectroscopy and multivariate analysis showed significant differences in some metabolites between the nontransgenic and transgenic leaves and roots. The overproduction of proline has reduced the sucrose content in transgenic leaves, revealing a metabolic cost for these plants. In roots, the high level of free proline acts for the adjustment of cation–anion balance, causing the reduction of acetic acid content. The same sucrose level in roots indicates that they can be considered as sucrose sink. Similar behavior may be waited for fruits produced on transgenic rootstock. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
584.
Gabriel M. de Oliveira Leandro L. Vieira da Rocha Admilson T. Franco Cezar O.R. Negrão 《ournal of non Newtonian Fluid Mechanics》2010,165(19-20):1114-1128
This paper describes a mathematical model used to simulate the restart of an axial, compressible and transient flow of a Bingham fluid in circular or annular pipes. The model is based on the mass and momentum conservation equations plus a state equation that relates pressure to density. The viscous effect is modeled by employing a friction factor approach. The governing equations are discretized by using the finite volume method with a first-order upwind scheme, and the resulting non-linear algebraic equations are then solved iteratively. The model results were corroborated by an analytical solution for Newtonian flows. Additionally, the results were also in reasonable agreement with results reported in the literature. We also conducted sensitivity analyses with respect to Reynolds number, aspect ratio, gravity and the non-linear advective terms of the governing equations. 相似文献
585.
M. Barroso M. Dias D. N. Vieira M. López-Rivadulla J. A. Queiroz 《Analytical and bioanalytical chemistry》2010,396(8):3059-3069
A simple procedure has been developed and validated for the qualitative and quantitative analysis of several opiates (morphine,
6-acetylmorphine, codeine, 6-acetylcodeine) and tramadol in hair. The analytes were extracted from within the matrix via an
overnight incubation with methanol at 65 °C, and afterwards the samples were cleaned up by mixed-mode solid-phase extraction.
The extracts were derivatized with N-methyl-N-(trimethylsilyl) trifluoroacetamide with 5% trimethylchlorosilane and analyzed by gas chromatography–mass spectrometry in
the selected ion monitoring mode. The method was linear from 0.05 (lower limit of quantitation) to 50 ng/mg (40 ng/mg for
tramadol), with correlation coefficients higher than 0.99 for all compounds, accomplishing the cut-off values proposed by
the Society of Hair Testing for the detection of these substances in hair (0.2 ng/mg). Intra- and interday precision and trueness
were in conformity with the criteria normally accepted in bioanalytical method validation, and the sample cleanup step presented
a mean efficiency higher than 90% for all analytes. Furthermore, using these incubation conditions, 6-acetylmorphine did not
significantly hydrolyze to morphine. For these reasons, and because of its simplicity, the proposed method can be successfully
applied in the determination of these compounds in hair samples, and is suitable for application in routine analysis with
forensic purposes. 相似文献
586.
Adriano M. Alencar Diego Greatti Vaz da Silva Carolina Beatriz Oliveira André P. Vieira Henrique T. Moriya Geraldo Lorenzi-Filho 《Physica A》2013
Snoring is extremely common in the general population and when irregular may indicate the presence of obstructive sleep apnea. We analyze the overnight sequence of wave packets — the snore sound — recorded during full polysomnography in patients referred to the Sleep Laboratory due to suspected obstructive sleep apnea. We hypothesize that irregular snore, with duration in the range between 10 and 100 s, correlates with respiratory obstructive events. We find that the number of irregular snores — easily accessible, and quantified by what we call the snore time interval index (STII) — is in good agreement with the well-known apnea–hypopnea index, which expresses the severity of obstructive sleep apnea and is extracted only from polysomnography. In addition, the Hurst analysis of the snore sound itself, which calculates the fluctuations in the signal as a function of time interval, is used to build a classifier that is able to distinguish between patients with no or mild apnea and patients with moderate or severe apnea. 相似文献
587.
P.M.A. de Farias B.S. Santos F.D. Menezes A.G. Brasil Jr. R. Ferreira M.A. Motta A.G. Castro-Neto A.A.S. Vieira D.C.N. Silva A. Fontes C.L. Cesar 《Applied Physics A: Materials Science & Processing》2007,89(4):957-961
Fluorescent semiconductor nanocrystals in quantum confinement regime (quantum dots) present several well-known features which
make them very useful tools for biological labeling purposes. Low photobleaching rates, high chemical stability and active
surface allowing conjugation to living cells explain the success of this labeling procedure over the commonly used fluorescent
dyes. In this paper we report the results obtained with highly fluorescent core–shell CdTe–CdS (diameter=3–7 nm) colloidal
nanocrystals synthesized in aqueous medium and conjugated to glucose molecules. The conjugated nanocrystals were incubated
with living yeast cells, in order to investigate their glucose up-take activity in real time, by confocal microscopy analysis.
PACS 87.83.+a; 61.46.Hk; 81.07.Ta 相似文献
588.
Carlos Rocha Oliveira Hudson Polonini Maria Cristina Marcucci Rodolfo P. Vieira 《Molecules (Basel, Switzerland)》2022,27(3)
Endometriosis presents high prevalence and its physiopathology involves hyperactivation of endometrial and vaginal cells, especially by bacteria. The disease has no cure and therapies aiming to inhibit its development are highly desirable. Therefore, this study investigated whether MiodesinTM (10 µg/mL = IC80; 200 µg/mL = IC50), a natural compound constituted by Uncaria tomentosa, Endopleura uchi, and astaxanthin, could exert anti-inflammatory and anti-proliferative effects against Lipopolysaccharides (LPS) stimulation in endometrial and Candida albicans vaginal cell lines. VK2 E6/E7 (vaginal) and KLE (epithelial) cell lines were stimulated with Candida albicans (1 × 107 to 5 × 107/mL) and LPS (1 μg/mL), respectively. MiodesinTM inhibited mRNA expression for Nuclear factor kappa B (NF-κB), ciclo-oxigenase 1 (COX-1), and phospholipase A2 (PLA2), beyond the C–C motif chemokine ligand 2 (CCL2), CCL3, and CCL5 in VK2 E6/E7 cells (p < 0.05). In addition, the inhibitory effects of both doses of MiodesinTM (10 µg/mL and 200 µg/mL) resulted in reduced secretion of interleukin-1β (IL-1β), IL-6, IL-8, tumor necrosis factor α (TNF-α) (24 h, 48 h, and 72 h) and CCL2, CCL3, and CLL5 (p < 0.05) by VK2 E6/E7 cells. In the same way, COX-1 MiodesinTM inhibited LPS-induced hyperactivation of KLE cells, as demonstrated by reduced secretion of IL-1β, IL-6, IL-8, TNF-α (24 h, 48 h, and 72 h) and CCL2, CCL3, and CLL5 (p < 0.05). Furthermore, MiodesinTM also inhibited mRNA expression and secretion of matrix metalloproteinase-2 (MMP-2), MMP-9, and vascular endothelial growth factor (VEGF), which are key regulators of invasion of endometrial cells. Thus, the study concludes that MiodesinTM presents beneficial effects in the context of endometriosis, positively affecting the inflammatory and proliferative response. 相似文献
589.
Tatiana F. Vieira Fbio G. Martins Joel P. Moreira Tiago Barbosa Srgio F. Sousa 《Molecules (Basel, Switzerland)》2021,26(20)
With tuberculosis still being one of leading causes of death in the world and the emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb), researchers have been seeking to find further therapeutic strategies or more specific molecular targets. PknB is one of the 11 Ser/Thr protein kinases of Mtb and is responsible for phosphorylation-mediated signaling, mainly involved in cell wall synthesis, cell division and metabolism. With the amount of structural information available and the great interest in protein kinases, PknB has become an attractive target for drug development. This work describes the optimization and application of an in silico computational protocol to find new PknB inhibitors. This multi-level computational approach combines protein–ligand docking, structure-based virtual screening, molecular dynamics simulations and free energy calculations. The optimized protocol was applied to screen a large dataset containing 129,650 molecules, obtained from the ZINC/FDA-Approved database, Mu.Ta.Lig Virtual Chemotheca and Chimiothèque Nationale. It was observed that the most promising compounds selected occupy the adenine-binding pocket in PknB, and the main interacting residues are Leu17, Val26, Tyr94 and Met155. Only one of the compounds was able to move the active site residues into an open conformation. It was also observed that the P-loop and magnesium position loops change according to the characteristics of the ligand. This protocol led to the identification of six compounds for further experimental testing while also providing additional structural information for the design of more specific and more effective derivatives. 相似文献
590.
L.G. Vieira O. Hernandez A. Almeida M. Quilichini J.L. Ribeiro M.R. Chaves A. Klöpperpieper 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(3):447-456
We report a combined experimental study by means of elastic neutron scattering and dielectric measurements of a partially
deuterated and brominated BCCD (Betaine Calcium Chloride Dihydrate) crystal. The lowest-temperature phase is one-dimensional modulated and
characterized by the coexistence of different commensurate domains (with = 1/4, 4/17, 2/9 and 1/5 on cooling), but with a clear predominance of the five-fold phase. A huge global thermal hysteresis
of the wave-vector of the modulation, attaining values of about 9 K in the incommensurate phase and up to 15 K in the “harmless”
low temperature part of the phase diagram, is observed up to . The role of lattice defects on this phenomenon is discussed. Similarly to the behaviour of the pure compound, the structural
modulation evolves on cooling towards a soliton regime (growth of third and fifth-order satellite peaks), probably with respect
to a non-stabilized non-modulated ferroelectric phase. The critical temperatures deduced from dielectric constant and pyroelectric
current measurements are in very good agreement with those obtained from neutron scattering. The dielectric anomaly observed
in at K, and known as the “-anomaly”, could not be related with any special feature detected in the neutron data, and in particular no correlation between
this anomaly and the appearance of the soliton regime can be established.
Received 26 October 1998 相似文献