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71.
Dr. Andreia Leite Dr. Luís Cunha-Silva Daniel Silva Dr. Ana I. M. C. Lobo Ferreira Prof. Luís M. N. B. F. Santos Inês C. S. Cardoso Dr. Vera L. M. Silva Prof. Maria Rangel Dr. Ana M. G. Silva 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(66):15073-15082
A series of pyridyl analogues of rosamines was prepared by employing two methodologies: (i) the conventional-heating condensation of a pyridinecarboxaldehyde with 3-(diethylamino)phenol in propionic acid, and (ii) the novel ohmic-heating assisted condensation under “on water” conditions, followed by oxidation. The 4-pyridyl substituted rosamine was further converted into the N-methylpyridinium derivative through N-alkylation using methyl iodide. The influence of the position and cationization of the nitrogen atom of the pyridyl ring in the physicochemical properties of fluorophores was investigated by 1H, 13C, 15N NMR spectral analysis, UV/Vis and fluorescence spectroscopy, single-crystal X-ray diffraction (4-pyridyl and N-methylpyridinium derivatives) and thermal-behavior analysis. Curiously, for ethanolic solutions of 4-pyridyl and N-methylpyridinium derivatives an extinction of color and fluorescence over time was observed. This phenomenon was further studied and the data revealed that it is the result of nucleophilic addition of ethoxide ion to the central 9-position of the xanthene. The kinetics of the process is slower for the 4-pyridyl rosamine, which emphasizes the importance of the charge in the N-methylpyridinium analogue in the reactivity of the molecule towards a nucleophile agent. This phenomenon is reversible, meaning that the compounds can be rapidly recovered by decreasing the pH, opening new avenues in the sensing applications of this class of rosamines. 相似文献
72.
Bleached acid sulphite and kraft Eucalyptus globulus pulps were subjected to treatment at high hydrostatic pressure (400 MPa during 10 min). The associated structural changes
of cellulose were evaluated by X-ray scattering, solid-state NMR and infrared spectroscopy. The high pressure treatment promoted
the growth of crystalline domains predominantly via lateral aggregation (cocrystallization) and, to some extent, due to the
accretion of cellulose from noncrystalline domains (recrystallization). The treated pulps exhibited increment of the amount
of strongly bound water and improved accessibility to amorphous domains. The high pressure treatment of dried sulphite pulp
led to restoration, at least partially, of its swelling capacity thus diminishing the hornification features. Pressure treated
dried sulphite pulp showed improved fibre bonding capacity at simultaneously increased bulk of the produced handsheets. The
results obtained clearly showed the potential of high pressure treatments for the modification of cellulosic fibres in different
applications. 相似文献
73.
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
74.
Humoral response against sialyl‐Lea glycosylated protein species in esophageal cancer: Insights for immunoproteomic studies 下载免费PDF全文
Andreia Peixoto Manuel Neves Luís Pedro Afonso Lúcio Lara Santos José Alexandre Ferreira 《Electrophoresis》2015,36(23):2902-2907
Esophageal cancers (ECs) show poor prognosis and decreased overall survival due to late diagnosis and ineffective therapeutics, urging the introduction of novel biomarkers to aid disease management. The levels of sialyl‐Lewis(a) antigen (sLea) are frequently increased in digestive tumours, which has been explored in serological non‐invasive prognostication (CA19‐9 test); however, with low sensitivity and specificity. Autoantibodies against cancer antigens are considered the next generation biomarkers, as they are present in circulation long before tumour‐associated proteins. Based on these observations we have mined the serum of EC patients (n = 7) for antibodies against sLea‐glycosylated protein species. All EC were positive for sLea, irrespectively of their histological nature but only two patients showed elevated CA19‐9. Moreover, IgG titers, with emphasis on IgG1, were elevated in EC patients in comparison to the control group. SLea‐glycoproteins were then extracted from tumours of patients with negative CA19‐9, isolated by immunoprecipitation and blotted with patients IgG. Autoantibodies against sLea‐glycosylated proteins were detected in all cases. Different SLea‐glycoproteins were observed for tumours of distinct histological natures, which now require identification and validation in larger patient sets. This preliminary data suggests that antoantibodies against sLea glycosylated proteins hold potential for non‐invasive diagnosis in CA19‐9 negative cases and sets the rational for future immunoproteomic studies envisaging highly specific EC biomarkers. 相似文献
75.
Kevy Pontes Eliodorio Vitor Seorra Andolfatto Marco Rulevas Gomes Martins Breno Pivaro de Sá Erick Ryoiti Umeki Andreia de Araújo Morandim-Giannetti 《Cellulose (London, England)》2017,24(6):2559-2570
This study proposes, verifies, and refines the use of biopolymers treated with two new ionic liquids (ILs) (sec-butylammonium acetate and n-octylammonium acetate), as a platform for chromium adsorption. The ILs were synthesized, characterized, and applied to chitosan treatment. Analyzing the size distribution of microparticles of chitosan and chitosan activated with ILs (sec-butylammonium acetate and n-octylammonium acetate), we observed that a little decrease in the particle size occurred with the activation of chitosan (176 ± 0.02 μm to 167 ± 0.054 and 168.5 ± 0.05 μm, respectively), as well as changes in the X-ray diffraction FTIR_ATR spectra. Further studies were performed using the best adsorbent – chitosan treated with sec-butylammonium acetate. In this case, the chromium VI concentration in the sample was reduced by more than 99% when using chitosan treated with IL sec-butylammonium acetate. The best reaction time was determined as 1 h, which allowed a chromium adsorption of 99.1% and the adsorption kinetic data were best represented by the second-order model (k2 = 11.7258 g mg?1 min?1). The maximum adsorption capacity was obtained using the Langmuir isotherm model (20.833 mg g?1 at pH 4 during 1 h, using 1.0 g of chitosan), and the adsorption efficiency was enhanced at 25 °C by the Freundlich isotherm model, in which the constants KF and n were determined as 0.875 mg L?1 and 1.610, respectively. 相似文献
76.
Izquierdo RA Barros CM Santana-Marques MG Ferrer-Correia AJ Silva EM Giuntini F Faustino MA Tomé JP Tomé AC Silva AM Neves GP Cavaleiro JA Peixoto AF Pereira MM Pais AA 《Journal of the American Society for Mass Spectrometry》2007,18(2):218-225
Electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS) have been used to differentiate the 2- and 4-methylpyridyl isomers of free-base and metallated cationic beta-vinylpyridylporphyrins. The analysis by ESI-MS/MS of the deuterated analogs and semiempirical calculations of structural and electronic parameters were also undertaken. The two free-base isomers are easily differentiated by ESI-MS/MS but the presence of a metallic center renders differentiation of the metallated isomers less effective. The data acquired show that of all the studied compounds, the free-base 2-methylpyridyl isomer, which was operative in the in vitro photoinactivation of Herpes simples virus, has a different gas-phase behavior. Local distortion of the macrocycle due to the presence of the beta-vinylpyridyl substituent occurs for all the compounds, but a different electron density distribution can account for the observed gas-phase behavior of this potential virus photoinactivator. 相似文献
77.
Daniel Machado de Alencar Juliana Gonalves Andreia Vieira Sofia A. Cerqueira Cruz Sebastio Maria Inês P. S. Leito Giulia Francescato Paola Antenori Helena Soares Ana Petronilho 《Molecules (Basel, Switzerland)》2021,26(21)
We report herein a set of 3′-azido-3′-deoxythymidine (AZT) derivatives based on triazoles and triazolium salts for HIV-1 infection. The compounds were synthesized via click chemistry with Cu(I) and Ru(II) catalysts. Triazolium salts were synthesized by reaction with methyl iodide or methyl triflate in good yields. The antiviral activity of the compounds was tested using two methodologies: In method one the activity was measured on infected cells; in method two a pre-exposure prophylaxis experimental model was employed. For method one the activity of the compounds was moderate, and in general the triazolium salts showed a decreased activity in relation to their triazole precursors. With method two the antiviral activity was higher. All compounds were able to decrease the infection, with two compounds able to clear almost all the infection, while a lower antiviral activity was noted for the triazolium salts. These results suggest that these drugs could play an important role in the development of pre-exposure prophylaxis therapies. 相似文献
78.
Andreia M. Correia Robin J. H. Clark Maria I. M. Ribeiro Maria L. T. S. Duarte 《Journal of Raman spectroscopy : JRS》2007,38(11):1390-1405
Twenty‐three paintings by Henrique Pousão—a 19th century Portuguese painter—belonging to the collection of Museu Nacional Soares dos Reis, Porto, Portugal, were analysed by Raman microscopy. The fine focus of a 100× objective allowed the visualisation and individual identification of small grains. As a result, thirty‐seven compounds, namely, anatase, barium white, basic lead sulfate, brochantite, cadmium red, cadmium yellow, calcium carbonate, carbon‐based black, celadonite, chrome green, chrome orange, chrome yellow, cobalt blue, cochineal lake, copper sulfide, emerald green, iron(III) oxyhydroxide, iron(III) oxide, kaolinite, lead antimonate yellow, lead carbonate, lead white, lead sulfate, madder lake, malachite, Prussian blue, quartz, realgar/pararealgar, red lead, rutile, Scheele's green, strontium yellow, ultramarine blue, vermilion, viridian, zinc white and zinc yellow, were identified. Not all these compounds are pigments; some are extenders, others trace components and others probably products of reactions between pigments. Special attention was given to the Raman characterisation of celadonite, chrome orange, basic lead sulfate and lead antimonate yellow. Complementary techniques were used to confirm the identities of certain pigments and to characterise reference samples. Pousão, whose work has not previously been studied spectroscopically, was found to have used a remarkably wide range of pigments over his painting periods, without showing significant preference for any particular set of pigments. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
79.
Andreia Ascenso Aida Duarte Alexandra Silva Ana Salgado Helena Cabral Marques 《Journal of inclusion phenomena and macrocyclic chemistry》2011,69(3-4):339-343
The aim of this work was to develop and characterize a 0.05% tretinoin hydrogel formulations in which tretinoin is free or complexed with dimethyl-beta-cyclodextrin in order to compare the main advantages of its complexation. Theoretically, the complexation will mainly allow to: overcome drug low solubility in water and low stability; enhance the drug release by promoting skin absorption and alleviate of drug inducing local irritation. The hydrogels prepared were both microbiological and physically stable during 30 days. However, the chemical stability was less encouraging. The complexed tretinoin gel had also a higher releasing profile than the free tretinoin gel. This study has demonstrated that it is possible to obtain a microbiological and physically stable gel formulation with good releasing profile. 相似文献
80.
Andreia Valente Philippe Zinck André Mortreux Marc Visseaux 《Journal of polymer science. Part A, Polymer chemistry》2011,49(7):1615-1620
A series of lanthanum and neodymium borohydrido complexes comprising the trisborohydrides Nd(BH4)3(THF)3 ( 1a ) and La(BH4)3(THF)3 ( 1b ) and the half‐lanthanidocenes Cp*Nd(BH4)2(THF)2 ( 2a ) (Cp* = C5Me5) and Cp*La(BH4)2(THF)2 ( 2b ) has been assessed for the chain transfer copolymerization of isoprene and styrene. A transmetalation process is occurring efficiently with the borohydride complexes in the presence of magnesium dialkyl. The transmetalation is accompanied by (i) a gradual decrease of the 1,4‐trans stereoselectivity of the reaction at the benefit of 3,4‐selectivity and (ii) an increase in the quantity of styrene inserted in the copolymer. This can be at least partially attributed to a magnesium induced co‐oligomerization of isoprene and styrene. By combining dialkylmagnesium and trialkylaluminum, a 1,4‐trans stereospecific reversible coordinative chain transfer copolymerization of isoprene and styrene is observed when the half‐lanthanocene 2b is used as precatalyst. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献