Search results for "ROMA"
showing 10 items of 13919 documents
Crystallographic and (spectro)electrochemical characterizations of cobalt(II) 10-phenyl-5,15-di-p-tolylporphyrin
2021
International audience; The synthesis, cyclic and rotating disk electrode voltammograms, UV-visible absorption and Xray diffraction analyses of cobalt(II) 10-phenyl-5,15-dip -tolylporphyrin (1-Co) are described. 1-Co was crystallized by slow diffusion of n-hexane into a concentrated CH2Cl2 solution. X-ray diffraction analyses reveals porphyrin aromatic cycle stacking in the crystal, C-H•••π interactions of the CH2Cl2 solvent with the π-system of one tolyl group and Co(II)•••π (porphyrin ring) interactions. The abstraction of 1.0 F/mol during the electrolysis at the first oxidation potential was followed by spectroelectrochemistry. It leads to the Co(II) → Co(III) transformation rather than …
Analysis of the U L3-edge X-ray absorption spectra in UO2 using molecular dynamics simulations
2017
This work was supported by a grant from the Swiss National Supercomputing Centre (CSCS) under the project ID s444. The resource allocation within the PSI share at CSCS and on the PSI compute cluster Merlin4 is also acknowledged. D. B. is grateful for a fellowship within the Sciex-NMS programme. A. K. was supported by Latvian Science Council Grant no. 187/2012.
Ag11(SG)7 : A New Cluster Identified by Mass Spectrometry and Optical Spectroscopy
2014
We report a one-step and high yield synthesis of a red-luminescent silver cluster with the molecular formula, Ag11(SG)7 (SG: glutathionate) via reduction of silver ions by sodium borohydride in the presence of the tripeptide, glutathione (GSH). The as-prepared cluster shows prominent absorption features at 485 and 625 nm in its UV-vis absorption spectrum. Aging of the as-prepared cluster solution led to the disappearance of the 625 nm peak, followed by broadening of the 485 nm peak to give three maxima at ?487, 437, and 393 nm in its absorption spectrum. These peaks remain unchanged even after polyacrylamide gel electrophoresis (PAGE), where a single band was observed confirming high purity…
Matei Visniec: aproximación a un universo dramático a través de sus animales
2014
Matei Visniec (1956) is an author from Romania, who uses both French and Romanian expression in his plays. The coordinates of his dramatic fictional universe bring together the absurd, the symbolic, the fantastic and the conflicts in the city of men, sometimes with accurate historical and current references. Animals, present onstage in many different ways, are very common in his plays. They constitute a strange wildlife between animal and human, between the real and the fantastic.Their presence in this theatrical universe fits into their symbolic aspect, which defies the imagination by means of what is enigmatic and incomprehensible; but it also falls into their committed side to the extent…
Optical absorption of divalent metal tungstates: Correlation between the band-gap energy and the cation ionic radius
2008
We have carried out optical-absorption and reflectance measurements at room temperature in single crystals of AWO4 tungstates (A = Ba, Ca, Cd, Cu, Pb, Sr, and Zn). From the experimental results their band-gap energy has been determined to be 5.26 eV (BaWO4), 5.08 eV (SrWO4), 4.94 eV (CaWO4), 4.15 eV (CdWO4), 3.9-4.4 eV (ZnWO4), 3.8-4.2 eV (PbWO4), and 2.3 eV (CuWO4). The results are discussed in terms of the electronic structure of the studied tungstates. It has been found that those compounds where only the s electron states of the A2+ cation hybridize with the O 2p and W 5d states (e.g BaWO4) have larger band-gap energies than those where also p, d, and f states of the A2+ cation contribu…
A comparative study on sample preparation procedures for supplementary foods by ICP-OES: Green chemistry considerations
2015
An inductively coupled plasma optical emission (ICP-OES) method was developed for the simultaneous determination of major, minor and trace elements in food. Preliminary studies focused on selecting suitable operational conditions in order to provide the highest sensitivity and to maximize the number of analytes to be determined without spectral or matrix interference. Ruthenium and rhenium were evaluated as internal standards and samples were analyzed at different dilution levels. Furthermore, a comparative study was carried out by using three sample digestion methods, microwave-assisted digestion with HNO3/H2O2, dry ashing and dry ashing with Mg(NO3)2/MgO as an ashing aid. Adequate precisi…
Fluorimetric determination of amphetamine in urine by flow injection with on-line liquid–liquid extraction
2001
Abstract Determination of amphetamine in urine was performed by batch and flow injection methodologies. The suitable experimental conditions for fluorimetric measurements were established. The liquid–liquid extraction was carried out at pH 13 using diethyl ether as extracting reagent. The measurement conditions were 260 nm and 277 nm for excitation and emission wavelengths, respectively. The method requires standard addition calibration and Youden blank correction. The influence of the main metabolites of amphetamine and metamphetamine were studied. The accuracy and precision of the proposed method was tested and the method is adapted to the flow injection procedure with on-line extraction.
Development of microextraction techniques in combination with GC-MS/MS for the determination of mycotoxins and metabolites in human urine.
2017
Simple and highly efficient sample preparation procedures, namely, dispersive liquid–liquid microextraction and salting-out liquid–liquid extraction for the analysis of ten Fusarium mycotoxins and metabolites in human urine were compared. Various parameters affecting extraction efficiency were carefully evaluated. Under optimal extraction conditions, salting-out liquid–liquid extraction showed a better accuracy (84–96%) and precision (<14%) than dispersive liquid–liquid microextraction. Hence, a multibiomarker method based on salting-out liquid–liquid extraction followed by gas chromatography with tandem mass spectrometry was proposed. Satisfactory results in terms of validation were achiev…
Effectiveness of microwave based digestion procedures for the demineralization of human milk and infant formulas prior to fluorometric determination …
1996
The use of two types of microwave oven, one domestic (A) and the other specially designed for laboratory (B) for microwave-based digestion, to destroy the organic matter in milk and infant formulas prior to fluorometric determination of selenium is studied in order to check their applicability and reliability. In both systems the best results were obtained using the acid mixture HNO3—H2O2, and additional treatment with perchloric acid (60%) in a Thermoblock. The application of two different microwave-based digestion procedures to infant formulas was free of interferences. In the case of human milk, it was necessary to use the standard addition method. Values obtained for detection and quant…
Quantitative evaluation of the phenolic profile in fruits of six avocado (Persea americana) cultivars by ultra-high-performance liquid chromatography…
2016
The phenolic profiles of six varieties of avocado (Persea americana) grown in Sicily were investigated. The ultra-high-performance liquid chromatography-heated electrospray-mass spectrometry method was developed to determine qualitative and quantitative changes in fruits at two different ripening stage. Nineteen individual phenolic compounds were detected in avocado pulp extracts. Gallic acid, sinapinic acid, vanillin, p-coumaric acid, and gentisic acid were present only in ripe fruits. On the contrary, epicatechin decreased with fruit ripening, whereas protocatechuic acid, 4-hydroxybenzoic acid, chlorogenic acid, and benzoic acid were relatively stable or exhibited erratic changes with fru…