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111.
Corinne Loutelier‐Bourhis Ornella Zovi Laurence Lecamp Claude Bunel Catherine M. Lange 《Rapid communications in mass spectrometry : RCM》2009,23(23):3743-3752
A detailed characterization of triacylglycerols (TAGs) present in linseed oil samples from a local producer was performed using electrospray ionization and two mass spectrometric approaches; direct infusion multi‐stage mass spectrometry (MSn) experiments and liquid chromatography/tandem mass spectrometry (LC/MS/MS) using non‐aqueous reversed‐phase chromatographic conditions. The combination of both approaches permitted the identification of 26 TAGs. Comparison of the two analytical approaches showed that discrimination of regioisomers was achieved from MS3 data while other isobaric species were separated and identified by LC/MS/MS analysis. The results we obtained were also compared with those previously reported. The TAG composition of the studied linseed oil is qualitatively identical to that of linseed oils from various sources in Europe, Canada, Argentina or India. However, a few differences were observed with regard to the proportions of some TAGs; these can be explained by variations in the culture conditions, climate, and variety of the seeds. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
112.
Mauro Bassetti Ilaria Fratoddi Laura Lilla Chiara Pasquini Maria Vittoria Russo Ornella Ursini 《Journal of polymer science. Part A, Polymer chemistry》2012,50(24):5097-5106
Terminal aryl alkynes RC6H4C?CH with substituents of different electronic properties and ring position (R = H, 4‐CF3, 4‐OMe, 2‐CF3, 2‐OMe, 2‐Me) were exposed to γ‐radiation (50–400 kGy) in organic solvents (hexane, 1,4‐dioxane, ethylacetate, methanol, tetrahydrofuran), at room temperature. The effects arising from substituent, solvent, dilution, and radiation dose allowed to define the conditions suitable for polymerization, which was favored in methanol at increasing dilution of the alkyne. Ortho‐substitution represented the key structural element in the substrate, and the derived polyarylacetylenes were characterized in detail, including gel permeation chromatography, thermal analysis, infrared, NMR, UV–vis, fluorescence, and scanning electron microscope spectroscopy. The results are consistent with the formation of irregular polymers mainly composed of trans‐transoid chains. Controlled aggregation of the polymers by means of an osmosis‐based procedure in solvent/non‐solvent mixtures allowed the formation of nanostructured materials, in particular of hollow nanospheres from THF/water. The methodology sets the basis for the development of γ‐rays‐induced polymerization of alkynes, in a transition metal catalyst‐free environment. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
113.
Preisner O Lopes JA Guiomar R Machado J Menezes JC 《Analytical and bioanalytical chemistry》2007,387(5):1739-1748
Rapid and reliable discrimination among clinically relevant pathogenic organisms is a crucial task in microbiology. Microorganism resistance to antimicrobial agents increases prevalence of infections. The possibility of Fourier transform infrared (FT-IR) spectroscopy to assess the overall molecular composition of microbial cells in a non-destructive manner is reflected in the specific spectral fingerprints highly typical for different microorganisms. With the objective of using FT-IR spectroscopy for discrimination between diverse microbial species and strains on a routine basis, a wide range of chemometrics techniques need to be applied. Still a major issue in using FT-IR for successful bacteria characterization is the method for spectra pre-processing. We analyzed different spectra pre-processing methods and their impact on the reduction of spectral variability and on the increase of robustness of chemometrics models. Different types of the Enterococcus faecium bacterial strain were classified according to chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis (PFGE). Samples were collected from human patients. Collected FT-IR spectra were used to verify if the same classification was obtained. In order to further optimize bacteria classification we investigated whether a selected combination of the most discriminative spectral regions could improve results. Two different variable selection methods (genetic algorithms (GAs) and bootstrapping) were investigated and their relative merit for bacteria classification is reported by comparing with results obtained using the entire spectra. Discriminant partial least-squares (Di-PLS) models based on corrected spectra showed improved predictive ability up to 40% when compared to equivalent models using the entire spectral range. The uncertainty in estimating scores was reduced by about 50% when compared to models with all wavelengths. Spectral ranges with relevant chemical information for Enterococcus faecium bacteria discrimination were outlined. 相似文献
114.
Ornella Pisacane 《4OR: A Quarterly Journal of Operations Research》2009,7(2):199-202
This is a summary of the author’s PhD thesis, supervised by Pierre L’Ecuyer and Roberto Musmanno and defended on 21 February
2008 at the Università della Calabria. The thesis is written in English and is available from the author upon request. This
work deals with the comparison of simulation-based algorithms for solving the agents scheduling problem in a multiskill call
center minimizing their costs under service levels constraints. A solution approach, combining simulation, with integer or
linear programming, and cut generation, is proposed. Considering realistic problems, it performs better than the two-step
approach proposed in the literature. It is also shown that a randomized search, extending the one defined for the single-period
staffing problem in Avramidis et al. [IIE Trans (in press), 2008], yields highly suboptimal solutions. Finally, an extension
of the cutting plane method to directly control the probability on the customers abandonments is designed.
相似文献
115.
Paolo Stabile Alessandro Lamonica Damiano Castoldi Ornella Curcuruto 《Tetrahedron letters》2010,51(24):3232-15296
A mild, general, convenient and practical methodology for the selective copper-mediated mono N-arylation of unprotected 2-imidazolidinone was developed. Strong electron-donating groups and free hydroxy and amino groups on the aryl iodide substrates were well tolerated. The use of n-butanol as the solvent for the copper-catalysed mono-arylation of 2-imidazolidinone is unprecedented. 相似文献
116.
Walthall DA Karty JM Römer B Ursini O Brauman JI 《The journal of physical chemistry. A》2005,109(39):8785-8793
Photodetachment cross sections for a series of cyclic enolates were measured using a continuous wave (CW) ion cyclotron resonance instrument to generate and detect the ions. We report electron affinities for the radicals corresponding to the removal of the extra electron from the following anions: 2-methylcyclopent-1-enolate, 3-methylcyclopent-1-enolate, 4-methylcyclopent-1-enolate, 5-methylcyclopent-1-enolate, 2-methylcyclohex-1-enolate, 3-methylcyclohex-1-enolate, 4-methylcyclohex-1-enolate, 4-ethylcyclohex-1-enolate, 5-methylcyclohex-1-enolate, and 6-methylcyclohex-1-enolate. Some of these anions are mixed with their tautomers, derived from deprotonation of the parent ketone; the consequences of this are analyzed. The effect of alkylation on the electron affinities is discussed. The effect of vibrational modes on the lifetimes of the dipole-bound states of 4-methylcyclohex-1-enolate and 4-ethylcyclohex-1-enolate is discussed. 相似文献
117.
Donata Favretto Roberta Seraglia Pietro Traldi Ornella Curcuruto Mahmoud Hamdan 《Journal of mass spectrometry : JMS》1994,29(10):526-532
Several proteins in the relative molecular mass (RMM) range 1150–29000 are examined by means of both positive electrospray and matrix-assisted laser desorption/ionization mass spectrometry. Accuracy of the measured RMMs, resolution and overall sensitivity are discussed. The presence of more than one component in a number of the investigated compounds permitted the assessment of both desorption methods for the analysis of mixtures. Solvent-induced conformational changes are linked to charge-state distribution shifts observed in some positive electrospray mass spectra. 相似文献
118.
Ornella Curcuruto Pietro Traldi Gloriano Moneti Luciana Corda Gianni Podda 《Journal of mass spectrometry : JMS》1991,26(8):713-717
The fast atom bombardment mass spectrometry of some crown ethers shows the formation of both [M + H]+ and [M ? H]+ ions, paralleling behaviour already observed using electron impact ionization. The study of these oily samples with and without a glycerol matrix, trifluoroacetic acid or alkali metal salts, suggests that the ionization process does not occur in the condensed phase, but in the selvedge region by gas-phase ion-molecule reactions in accordance with the ‘gas-phase explosion model’. Positive-ion chemical ionization experiments support this proposal. 相似文献
119.
Batista Alzir A. Wonrath Karen Queiroz Salete L. Porcu Ornella M. Castellano Eduardo E. Barberato Claudio 《Transition Metal Chemistry》2001,26(3):365-368
The compound [RuCl2(CO)(DMA)(PPh3)2] [DMA = dimethylacetamide] was obtained from [RuCl3(PPh3)2-(DMA)] · DMA and CO in DMA. Orange crystals of [RuCl2(CO)(DMA)(PPh3)2] · 1/2CH2Cl2 were isolated by slow evaporation of a CH2Cl2/DMA solution and its structure was determined by single crystal X-ray diffraction. The analogous compounds containing DMF and DMSO were obtained from the precursor ttt-[RuCl2(CO)2(PPh3)2]. Characterization of the other complexes is based on i.r. and n.m.r. spectroscopy, including 31P{1H} data. 相似文献
120.
Ornella Curcuruto Gordon Kennedy Mahmoud Hamdan 《Journal of mass spectrometry : JMS》1994,29(10):547-552
Solutions containing one or more aminoglycosides have been investigated by positive electrospray mass spectrometry. The lack of extensive fragmentation in the acquired mass spectra permitted reliable identification of the individual components within the electrosprayed solutions. Results obtained at relatively high cone voltage allowed confident assignment of the major fragmentation pathways under electrospray conditions. The presented data also indicate that higher cone voltage favours the observation of sodium adduct ions, [M + Na]+. This experimental observation is tentatively attributed to a less efficient cone-assisted collision-induced dissociation of these species compared to their [M + H]+ counterparts. 相似文献