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101.
Ramos CI Barros CM Fernandes AM Santana-Marques MG Correia AJ Tomé JP Carrilho Mdo C Faustino MA Tomé AC Neves MG Cavaleiro JA 《Journal of mass spectrometry : JMS》2005,40(11):1439-1447
Electrospray ionisation mass spectrometry (ESI-MS), electrospray ionisation tandem mass spectrometry (ESI-MS/MS) and Ultraviolet-visible (UV-vis) spectroscopy were used to investigate the non-covalent interactions between small oligonucleotide duplexes with the GC motif and a group of cationic meso(N-methylpyridynium-4-yl)porphyrins (four free bases with one to four positive charges, and the zinc complex of the tetracationic free base).The results obtained point to outside binding of the porphyrins, with the binding strength increasing with the number of positive charges. Fragmentations involving losses from both chains were observed for the porphyrins with N-methylpyridinium-4-yl groups in opposite meso positions. 相似文献
102.
Ana Paula Barrêto Gomes Lidiane Pinto Correia Mônica Oliveira da Silva Simões R. O. Macêdo 《Journal of Thermal Analysis and Calorimetry》2007,88(2):383-387
The objective of this work was to develop
and validate a fast and reproducible method to determine the concentration
of metronidazole in drug substance and tablets. The samples were analyzed
by dynamic thermogravimetry, using 10, 20, 40, 60 and 80°C min–1
heating rates in nitrogen and in nitrogen with synthetic air. Obtained data
were used in the Antoine and Langmuir equations in order to have the pressure
curves. Vapor pressure curves of drug and tablet of metronidazole were evaluated
using the mathematical indexes of difference factor, f
1,
and similarity factor, f
2,
to compare their profiles. The data showed that there is no significant difference
between the vapor pressure profiles of drug and tablet of metronidazole in
both environmental conditions, which confirms that the process is really vaporization.
The concentration of metronidazole was determined in the raw material and
tablets of the drug. 相似文献
103.
Ramos CI Santana Marques MG Correia AJ Serra VV Tomé JP Tomé AC Neves MG Cavaleiro JA 《Journal of the American Society for Mass Spectrometry》2007,18(4):762-768
Reductions involving more than one electron with formation of the M+ and [M+2H]+ ions were observed for electrosprayed meso-tris(N-methylpyridinium-4-yl)porphyrin iodides, MI3. These reductions were studied by using different solvents and flow rates. Formation of the [M+2H]+ ions occurred only for protic solvents and to a larger extent at lower flow rates. The type of the fourth substituent does
not seem to affect the reduction processes. Formation of the two reduced species, M+ and [M+2H]+ ions, may occur through the participation of counter ion/solvent clusters. Reduction of multiply charged, non-metallated
species with formation of [M+nH]+ ions (n>1) was not observed before in positive mode electrospray mass spectrometry. 相似文献
104.
Plasmonic Nanorattles as Next‐Generation Catalysts for Surface Plasmon Resonance‐Mediated Oxidations Promoted by Activated Oxygen 下载免费PDF全文
Anderson G. M. da Silva Thenner S. Rodrigues Valquírio G. Correia Tiago V. Alves Rafael S. Alves Rômulo A. Ando Fernando R. Ornellas Jiale Wang Leandro H. Andrade Pedro H. C. Camargo 《Angewandte Chemie (International ed. in English)》2016,55(25):7111-7115
Nanorattles, comprised of a nanosphere inside a nanoshell, were employed as the next generation of plasmonic catalysts for oxidations promoted by activated O2. After investigating how the presence of a nanosphere inside a nanoshell affected the electric‐field enhancements in the nanorattle relative to a nanoshell and a nanosphere, the SPR‐mediated oxidation of p‐aminothiophenol (PATP) functionalized at their surface was investigated to benchmark how these different electric‐field intensities affected the performances of Au@AgAu nanorattles, AgAu nanoshells and Au nanoparticles having similar sizes. The high performance of the nanorattles enabled the visible‐light driven synthesis of azobenzene from aniline under ambient conditions. As the nanorattles allow the formation of electromagnetic hot spots without relying on the uncontrolled aggregation of nanostructures, it enables their application as catalysts in liquid phase under mild conditions using visible light as the main energy input. 相似文献
105.
Abstract— The modification of the lethal interaction between near-UV (365 nm) radiation and a second DNA-damaging agent by incubation between treatments in either a minimal salts medium or complete growth medium has been studied in the wild-type bacterial strain Escherichia coli K12 AB 1157. The results indicate that the lethal interaction may be separated into at least two distinct processes whose evaluation may help in classifying DNA-damaging agents in terms of the repairability of the DNA lesions induced. An observation of changes when methyl methane sulphonate is given prior to the irradiation treatment indicates that this chemical irreversibly damages repair enzymes. 相似文献
106.
Development of a SPME-GC-ECD methodology for selected pesticides in must and wine samples 总被引:2,自引:0,他引:2
A method for the determination of some pesticide residues in must and wine samples was developed using solid-phase microextraction (SPME) and gas chromatography-electron capture detection (GC/ECD). The procedure only needs dilution as sample pre-treatment and is therefore simple, fast and solvent-free. Eight fungicides (vinclozolin, procymidone, iprodione, penconazole, fenarimol, folpet, nuarimol and hexaconazole), one insecticide (chlorpyriphos) and two acaricides (bromopropylate and tetradifon) can be quantified. Good linearity was observed for all the compounds in the range 5-100 microg/L. The reproducibility of the measurements was found acceptable (with RSD's below 20%). Detection limits of 11 microg/L, on average, are sufficiently below the proposed maximum residue limits (MRL's) for these compounds in wine. The analytical method was applied to the determination of these compounds in Portuguese must and wine samples from the Demarcated Region of Alentejo, where any residues could be detected. 相似文献
107.
S. Pereira M. R. Correia T. Monteiro E. Pereira M. R. Soares E. Alves 《Journal of Crystal Growth》2001,230(3-4):448-453
We studied the structural and optical properties of a set of nominally undoped epitaxial single layers of InxGa1−xN (0<x0.2) grown by MOCVD on top of GaN/Al2O3 substrates. A comparison of composition values obtained for thin (tens of nanometers) and thick (≈0.5 μm) layers by different analytical methods was performed. It is shown that the indium mole fraction determined by X-ray diffraction, measuring only one lattice parameter strongly depend on the assumptions made about strain, usually full relaxation or pseudomorphic growth. The results attained under such approximations are compared with the value of indium content derived from Rutherford backscattering spectrometry (RBS). It is shown that significant inaccuracies may arise when strain in InxGa1−xN/GaN heterostructures is not properly taken into account. Interpretation of these findings, together with the different criteria used to define the optical bandgap of InxGa1−xN layers, may explain the wide dispersion of bowing parameters found in the literature. Our results indicate a linear, Eg(x)=3.42−3.86x eV (x0.2), “anomalous” dependence of the optical bandgap at room temperature with In content for InxGa1−xN single layers. 相似文献
108.
V. S. Makhmutov J. -P. Raulin R. R. S. De Mendonca G. A. Bazilevskaya E. Correia P. Kaufmann A. Marun G. Fernandez E. Echer 《Bulletin of the Russian Academy of Sciences: Physics》2013,77(5):500-502
The CARPET cosmic ray detector was installed in 2006 in the Argentinean Andes at an altitude of 2550 m at the El Leoncito Astronomical Complex (CASLEO) in San Juan, Argentina (S31.8, W69.3; R c = 9.659.65 GV). This instrument was developed at the Lebedev Physical Institute (LPI) in Russia as part of an international collaboration between the LPI, Brazil’s Mackenzie Center for Radioastronomy and Astrophysics (CRAAM), and the CASLEO. This work presents the results from analyzing variations in cosmic ray intensity recorded by the CARPET facility during the solar proton event of March 7, 2011. Also used in our analysis were the experimental data obtained by the GOES, FERMI, and ISS spacecraft during this solar event. 相似文献
109.
Carlos Roque D. Correia Caio C. Oliveira Airton G. Salles Emerson A.F. Santos 《Tetrahedron letters》2012,53(26):3325-3328
Successful enantioselective Heck–Matsuda arylations were accomplished for the first time using chiral bisoxazolines as ligands. Enantioselective Heck arylations were performed with several cyclic nonactivated olefins to provide the Heck products in 63–96% isolated yields and in enantiomeric excesses of 54% up to 84%. 相似文献
110.