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231.
232.
Castillo John J. Rindzevicius Tomas Wu Kaiyu Schmidt Michael S. Janik Katarzyna A. Boisen Anja Svendsen Winnie Rozlosnik Noemi Castillo-León Jaime 《Journal of nanoparticle research》2014,16(7):1-8
Traditionally, organosilica nanoparticles have been prepared inside micelles with an external silica shell for mechanical support. Here, we compare these hybrid core–shell particles with organosilica particles that are robust enough to be produced both inside micelles and alone in a sol–gel process. These particles form from octadecyltrimethoxy silane as silica source either in microemulsions, resulting in water-dispersible particles with a hydrophobic core, or precipitate from an aqueous mixture to form particles with both hydrophobic core and surface. We examine size and morphology of the particles by dynamic light scattering and transmission electron microscopy and show that the particles consist of Si–O–Si networks pervaded by alkyl chains using nuclear magnetic resonance, infrared spectroscopy, and thermogravimetric analysis. 相似文献
233.
Franciele Wolfart Amanda Maciel Noemi Nagata Marcio Vidotti 《Journal of Solid State Electrochemistry》2013,17(5):1333-1338
This paper concerns the deposition of metal alloys formed by nickel and copper on electrode surface aiming at the development of electrocatalytic systems. Such alloys were formed on platinum electrodes by direct reduction of Ni2+ and Cu2+ sulfate salts in different proportions in a simple and straightforward electrochemical treatment. After the deposition, the conversion to the electrocatalytic oxide form was done in alkaline solutions by cyclic voltammograms. The experimental parameters, such as deposition time and the proportion of copper and nickel in the synthetic solution, were investigated toward the catalytic oxidation of glucose. The materials were characterized by electrochemical experiments, infrared and Raman spectroscopies, and X-ray diffraction, showing that the material is not a simple mixture of nickel and copper oxides. The modified electrodes showed remarkable electrocatalytic properties, indicating an interesting application in the sensor and fuel cell development. 相似文献
234.
Maria Alicia Pugliese Maria Teresa Goitia Mariana Yossen Norma Cifone Enrique Agulló Noemi Andreucetti 《Radiation Physics and Chemistry》2011,80(12):1406-1413
Different molecular weight chitosans were evaluated on the decay of coated Anquito squashes (Cucurbita moschata) as well as the maintenance of the fruit quality along five storage months. The original chitosan (Mw=391 kDa, 83% DD), was depolymerized by gamma radiation. Apart from chain scission, other chemical changes were not detected by FTIR or UV–vis analyses. The molecular weight characterization of chitosans was done by size exclusion chromatography with dual light scattering and concentration detection (SEC-MALLS-RI). The coating effectiveness was evaluated on the following parameters: fungal decay incidence, weight loss, firmness, total reducing sugar, soluble solid, flesh color, carotene content, pH and titratable acidity. No sign of fungal decay was observed in squashes coated with 122 and 56 kDa chitosans, which were also the most effective treatments in reducing the weight loss. The chitosan with Mw=122 kDa was also the best treatment considering firmness, internal aspect, sugar and carotene content. Then, radiation degraded chitosan was better in C. moschata preservation than the original chitosan. 相似文献
235.
Valeria Di Tullio Noemi Proietti Marco Gobbino Donatella Capitani Roberto Olmi Saverio Priori Cristiano Riminesi Elisabetta Giani 《Analytical and bioanalytical chemistry》2010,396(5):1885-1896
As is well known, the deterioration of wall paintings due to the capillary rise of water through the walls is a very widespread
problem. In this paper, a study of microclimate monitoring, unilateral nuclear magnetic resonance (NMR), and evanescent-field
dielectrometry (EFD) was applied to map non-destructively, in situ, and in a quantitative way the distribution of the moisture
in an ancient deteriorated wall painting of the eleventh century. Both unilateral NMR and EFD are quite new, fully portable,
and non-destructive techniques, and their combination is absolutely new. The approach reported here is proposed as a new analytical
protocol to afford the problem of mapping, non-destructively, the moisture in a deteriorated wall painting in a hypogeous
building such as that of the second level of St. Clement Basilica, Rome (Italy), where the use of IR thermography is impaired
due to the environmental conditions, and the gravimetric tests are forbidden due to the preciousness of the artifact. The
moisture distribution was mapped at different depths, from the very first layers of the painted film to a depth of 2 cm. It
has also been shown how the map obtained in the first layers of the artwork is affected by the environmental conditions typical
of a hypogeous building, whereas the maps obtained at higher depths are representative of the moisture due to the capillary
rise of water from the ground. The quantitative analysis of the moisture was performed by calibrating NMR and EFD signals
with purposely prepared specimens. This study may be applied before and after performing any intervention aimed at restoring
and improving the state of conservation of this type of artwork and reducing the dampness or extracting salts (driven by the
variation of moisture content) and monitoring the effectiveness of the performed interventions during the time. This protocol
is applicable to any type of porous material. 相似文献
236.
Rodríguez-Flores J Berzas Nevado JJ Contento Salcedo AM Cabello Díaz MP 《Journal of chromatography. A》2005,1068(1):175-182
The viability of nonaqueous capillary electrophoresis (NACE) was investigated for determination of gleevec and its main metabolite in human urine using a fused-silica capillary. Baseline separation of the studied solutes was obtained using a nonaqueous solution composed of 12 mM ammonium acetate and 87.6 mM acetic acid in methanol-acetonitrile (ACN) (80:20, v:v) providing analysis time shorter than 3 min. Different aspects including stability of the solutions, linearity, accuracy and precision were studied in order to validate the method in the urine matrix. Detection limits of 24 microg L(-1) for gleevec and its metabolite were obtained. A robustness test of the method was carried out using the Plackett-Burman fractional factorial model with a matrix of 15 experiments. The developed method is simple, rapid and sensitive and has been used to determine gleveec and its metabolite at clinically relevant levels in human urine. Before NACE determination, a solid-phase extraction (SPE) procedure with a C18 cartridge was necessary. Real determination of these analytes in two patient urines were done. 相似文献
237.
Rodríguez Flores J Barzas Nevado JJ Contento Salcedo AM Cabello Díaz MP 《Electrophoresis》2004,25(3):454-462
A simple, rapid, and sensitive procedure using nonaqueous capillary electrophoresis (NACE) to measure Paroxetine (one of the mostly used antidepressants for mental diseases treatment) and three metabolites has been developed and validated. Optimum separation of paroxetine and metabolites was obtained on a 57 cm x 75 microm capillary using a nonaqueous buffer system of 9:1 methanol-acetonitrile containing 25 mM ammonium acetate and 1% acetic acid, with temperature and voltage of 25 degrees C and 15 kV, respectively, and hydrodynamic injection. Fluoxetine was used as an internal standard. Good results were obtained for different aspects including stability of the solutions, linearity, accuracy, and precision. Detection limits between 9.3 and 23.1 microg.L(-1) were obtained for paroxetine and its metabolites. A ruggedness test of the method was carried out using the Plackett-Burman fractional factorial model with a matrix of 15 experiments. This method has been used to determine paroxetine and its main metabolite B at clinically relevant levels in human urine. Prior to NACE determination, the samples were purified and enriched by means of an extraction-preconcentration step with a preconditioned C18 cartridge and eluting the compounds with methanol. 相似文献
238.
239.
240.
Cabello A 《Physical review letters》2004,92(6):060403
The combination of quantum correlations appearing in the Clauser-Horne-Shimony-Holt inequality can give values between the classical bound, 2, and Tsirelson's bound, 2 x square root of 2. However, for a given set of local observables, there are values in this range which no quantum state can attain. We provide the analytical expression for the corresponding bound for a parametrization of the local observables introduced by Filipp and Svozil, and describe how to experimentally trace it using a source of singlet states. Such an experiment will be useful to identify the origin of the experimental errors in Bell's inequality-type experiments and could be modified to detect hypothetical correlations beyond those predicted by quantum mechanics. 相似文献