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41.
Madureira AM Ascenso JR Valdeira L Duarte A Frade JP Freitas G Ferreira MJ 《Natural product research》2003,17(5):375-380
A phytochemical reinvestigation of the whole plant of Euphorbia segetalis yielded five tetracyclic triterpenes: 3beta-hydroxy-cycloart-25-en-24-one (1), cycloart-25-ene-3beta,24-diol (2), cycloart-23-ene-3beta,25-diol (3), lanosta-7,9(11),24-trien-3beta-ol (4) and lanosta-7,9(11),24(31)-trien-3beta-ol (5). beta-acetoxy-cycloart-25-en-24-one (1a) and glutinol (6), lupenone (7), dammaranodienol (9), cycloartenol acetate (10), 24-methylenecycloartanol acetate (11) and beta-sitosterol (12), isolated previously, were evaluated for their antiviral activities against Herpes simplex virus (HSV) and African swine fever virus (ASFV). Lupenone exhibited strong viral plaque inhibitory effect against HSV-1 and HSV-2. The in vitro antifungal and antibacterial activities of la, cycloart-23-ene-3beta,25-diol, 3-acetate (3a) and 6-12 were also investigated. 相似文献
42.
Eric Mayer-Santos Tatjana Maravic Allegra Comba Patricia Moreira Freitas Giovanna Bueno Marinho Claudia Mazzitelli Edoardo Mancuso Nicola Scotti Federica Florenzano Lorenzo Breschi Annalisa Mazzoni 《Molecules (Basel, Switzerland)》2022,27(5)
This study aimed to investigate matrix metalloproteinase (MMP) activity in human dentin using in-situ and gelatin zymography, after at-home and in-office bleaching, related to their clinical exposure times. Dentin specimens (n = 5) were treated with 35% hydrogen peroxide (50 min per session/4 sessions), 10% carbamide peroxide (180 min/21 sessions), or no treatment. All were subjected to in-situ zymography. Dentin slices were, subsequently, obtained, covered with fluorescein-conjugated gelatin, and examined with confocal laser-scanning microscopy. The fluorescence intensity was quantified and statistically analyzed using one-way ANOVA and Bonferroni tests (α = 0.05). Furthermore, gelatin zymography was performed on protein extracts obtained from dentin powder (N = 8 teeth), treated with hydrogen peroxide or carbamide peroxide, with different exposure times (10/50 min for hydrogen peroxide; 252/1260 min for carbamide peroxide). The results of the in-situ zymography showed no statistical differences between the bleached specimens and the control group, with a medium level of gelatinolytic activity expressed in the dentin tubules. The results of gelatin zymography showed an increased expression of pro-MMP-9 in carbamide peroxide groups. The expression of pro-MMP-2 decreased in all the experimental groups. The bleaching treatments performed on the enamel of sound teeth do not influence dentinal enzymatic activity. However, when unprotected dentin tissue is bleached, matrix metalloproteinases are more expressed, particularly when carbamide peroxide is used, proportional to the exposure time. 相似文献
43.
44.
Chen X Sichelschmidt O Kleemann W Petracic O Binek Ch Sousa JB Cardoso S Freitas PP 《Physical review letters》2002,89(13):137203
The ac susceptibility of a superferromagnetic discontinuous multilayer [Co(80)Fe20(1.4 nm)/Al(2)O3(3 nm)](10) is measured as a function of temperature, frequency, and field amplitude and compared to static and dynamic hysteresis loops. Its properties are successfully mapped onto the predicted [T. Nattermann, V. Pokrovsky, and V. M. Vinokur, Phys. Rev. Lett. 87, 197005 (2001)]] dynamical phase transitions, which link the relaxation, creep, sliding, and switching regimes of pinned domain walls. 相似文献
45.
D. G. Beasley A. Alghamdi M. C. Freitas A. Fernandes Z. Révay 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(2):307-311
The epithermal beamline at the Portuguese Research Reactor is being optimized for Prompt Gamma Neutron Activation Analysis
(PGNAA). One of the major changes is to thermalise the beam by the introduction of a sapphire crystal into the beamline. Placing
the sapphire at the exit of the beamline would greatly reduce the alterations and work necessary to the port and make the
crystal easily removable. However, the scattered neutrons from the sapphire would increase both the neutron-induced detector
damage and the background radiation. MCNPX was used to simulate the crystal in the beam port and at the exit of the port. 相似文献
46.
Tércio de Freitas Paulo Solange de Oliveira Pinheiro Maria Aparecida S. Da Silva Luiz Gonzaga de França Lopes Lucidalva S. Pinheiro Gil F. A. Aquino Márcia Laudelina Arruda Temperini Pedro de Lima Neto Izaura Cirino Nogueira Diógenes 《Electroanalysis》2009,21(9):1081-1089
STM and impedance results of the self‐assembled monolayer (SAM) formed with thionicotinamide (TNA) on gold indicate the presence of defects that increase with the immersion time of the electrode in the TNA solution affecting the SAM electroactivity toward the electron transfer reaction of the cytochrome c metalloprotein and [Fe(CN)6]4? and [Ru(NH3)6]3+ complexes. It was observed that this electroactivity was also affected by the pH of the electrolyte solution. SERS and STM data indicate sulfur coordination to the surface with contribution of the NH2 group. From the dependence of the TNA surface coverage on the temperature and concentration in solution, thermodynamic parameters of adsorption were determined. 相似文献
47.
H. M. Dung M. C. Freitas S. Sarmento M. Blaauw D. Beasley 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(3):621-625
A new Compton suppression system (CSS) for the gamma-ray spectrometer portion of the neutron activation analysis (NAA) was
set up at the RPI/ITN. The pneumatic transfer system, SIPRA, for short-lived nuclides and cyclic irradiations was improved.
A full calibration procedure of the CSS and SIPRA systems was performed. Two certified reference materials, NIST-SRM-1572
(Citrus Leaves) and NIST-SRM-1633a (Coal Fly Ash) were analyzed using the calibration factors. The CSS was instrumental in
lowering the detection limits of Cr, Fe, Hg, Rb, Sr, Th and Zn by reducing background and/or spectral interference considerably.
The analytical results were evaluated by comparison to the NIST certified values with deviations ranging from 2% to 8% for
the above mentioned elements, except Zn ranging from 10% to 15% for biological and environmental samples, respectively. 相似文献
48.
Dos Santos VA Dos Santos DP Castro-Gamboa I Zanoni MV Furlan M 《Molecules (Basel, Switzerland)》2010,15(10):6956-6973
This work describes the isolation of the secondary metabolites identified as the quinonemethides maytenin (1) and pristimerin (2) from Maytenus ilicifolia extracts obtained from root barks of adult plants and roots of seedlings and their quantification by high performance liquid chromatography coupled to a diode array detector. The electrochemical profiles obtained from cyclic voltammetry and a coulometric detector coupled to high-performance liquid chromatography contributed to the evaluation of their antioxidant capacity. The antioxidant properties of individual components and the crude extracts of the root barks of Maytenus ilicifolia were compared and the possible synergistic associations of quinonemethide triterpenes and phenolic substances were investigated by using rutin as a model phenolic compound. 相似文献
49.
N. Canha M. C. Freitas S. M. Almeida M. Almeida M. Ribeiro C. Galinha H. Th. Wolterbeek 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(2):495-500
Total particulate matter (TPM) was passively collected inside two classrooms of each of five elementary schools in Lisbon, Portugal. TPM was collected in polycarbonate filters with a 47 mm diameter, placed inside of uncovered plastic petri dishes. The sampling period was from 19 May to 22 June 2009 (35 days exposure) and the collected TPM masses varied between 0.2 mg and 0.8 mg. The major elements were Ca, Fe, Na, K, and Zn at μg level, while others were at ng level. Pearson′s correlation coefficients above 0.75 (a high degree of correlation) were found between several elements. Soil-related, traffic soil re-suspension and anthropogenic emission sources could be identified. Blackboard chalk was also identified through Ca large presence. Some of the determined chemical elements are potential carcinogenic. Quality control of the results showed good agreement as confirmed by the application of u-score test. 相似文献
50.
Alain?de?Roany J.?A.?de?Freitas PachecoEmail author 《General Relativity and Gravitation》2011,43(1):61-72
Cosmologies including continuous matter creation are able to reproduce the main properties of the standard ΛCDM model, in particular in cases where the particle and entropy production rates are equal. These specific models, characterized
by a mass density equal to the critical value, behave like the standard ΛCDM model at early times whereas their late evolution is similar to the steady-state cosmology. The maximum amplitude of density
fluctuations in these models depends on the adopted creation rate, related here to the parameter Ω
v
and this limitation could be a difficulty for the formation of galaxies and large-scale structure in this class of universe.
Additional problems are related with predictions either of the random peculiar velocities of galaxies or the present density
of massive clusters of galaxies, both being largely overestimated with respect to observational data. 相似文献