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131.
S. Failla P. Finocchiaro V. K. Belsky V. E. Zavodnik A. N. Sobolev 《Journal of inclusion phenomena and macrocyclic chemistry》1994,15(3):247-258
The title compound, C41H40N2O6S2, has been synthesised in good yield and was found to form a 11 inclusion compound with CHCl3 and other organic solvents. The crystal and molecular structure of the CHCl3 solvate has been determined by single crystal X-ray analysis and refined to anR-value of 0.034 for 3229 reflections. The compound is monoclinic, space groupP21/c, witha=15.316(1),b=14.515(1),c=18.720(3) Å, =101.98(1)o, andZ=4. One molecule of chloroform is included in the crystal lattice.
Supplementary data relevant to this article have been deposited with the British Library as Supplementary Publication No. SUP 82146 (9 pp.). 相似文献
132.
Andrea Speltini Mattia Maiocchi Lucia Cucca Daniele Merli Antonella Profumo 《Analytical and bioanalytical chemistry》2014,406(15):3657-3665
This is the first report on the analytical application of multiwalled carbon nanotubes (MWCNTs) as solid-phase extraction (SPE) sorbents for determination in surface waters, at the nanograms per litre level, of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), the two predominant contaminants among the perfluorinated compounds detected. After the preconcentration step, the quantification was achieved by ultraperformance liquid chromatography–electrospray ionization mass spectrometry. To increase the extraction efficiency towards these amphiphilic compounds, MWCNTs were derivatized with amino-terminated alkyl chains, thus producing a mixed-mode material (MWCNT-R-NH2) combining hydrophobic affinity and anion-exchange properties. Experiments with distilled, tap and river water (pH 3) spiked at different concentrations (10, 15, 30, 100, 200 and 500 ng L-1) provided absolute recoveries in the range 71–102 % (n?=?3, relative standard deviations less than 10 %). Analytes were eluted in a single fraction with 6 mL methanol (3?×?10-4 M NaOH). The within-laboratory reproducibility of the MWCNT-R-NH2 SPE sorbent was evaluated with raw river water, and relative standard deviations less than 15 % were obtained (n?=?4). Preconcentration factors up to 125 (500-mL sample) made it possible to quantify PFOA and PFOS at low nanograms per litre levels in naturally contaminated river water. The method quantification limits of 10 ng L-1 for PFOA and 15 ng L-1 for PFOS were well below the advisory levels for drinking and surface waters. Comparison with non-derivatized MWCNTs highlighted the role of functionalization in improving the adsorption affinity towards these contaminants. MWCNT-R-NH2 maintained their extraction capability for at least eight repeated adsorption/desorption cycles. 相似文献
133.
134.
We investigate the morphology of a pentacene (C22H14) film adsorbed on the Cu(1 1 9) vicinal surface by scanning tunnelling microscopy (STM). Thermal treatment of a thick film of molecules generates a long-range ordered structure. Series of molecular rows are alternated with areas where the molecules assume two equivalent orientations. STM data analysis suggests that the ordered structure can be described by a rippled morphology. The behaviour of the film at different annealing temperatures suggests a possible explanation of the film structure as due to an adsorbate-induced modification of the substrate. 相似文献
135.
Mattia Fogagnolo Lorenzo Mazzieri Andrea Pinamonti 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2019,36(4):1151-1179
We provide monotonicity formulas for solutions to the p-Laplace equation defined in the exterior of a convex domain. A number of analytic and geometric consequences are derived, including the classical Minkowski inequality as well as new characterizations of rotationally symmetric solutions and domains. The proofs rely on the conformal splitting technique introduced by the second author in collaboration with V. Agostiniani. 相似文献
136.
137.
Pagano B Mattia CA Cavallo L Uesugi S Giancola C Fraternali F 《The journal of physical chemistry. B》2008,112(38):12115-12123
Molecular dynamics simulations have been used to study the differences between two DNA and RNA 14-mer quadruplexes of analogous sequences. Their structures present a completely different fold: DNA forms a bimolecular quadruplex containing antiparallel strands and diagonal loops; RNA forms an intrastrand parallel quadruplex containing a G-tetrad and an hexad, which dimerizes by hexad stacking. We used a multiscale computational approach combining classical Molecular dynamics simulations and density functional theory calculations to elucidate the difference in stability of the 2-folds and their ability in coordinating cations. The presence of 2'-OH groups in the RNA promotes the formation of a large number of intramolecular hydrogen bonds that account for the difference in fold and stability of the two 14-mers. We observe that the adenines in the RNA quadruplex play a key role in conserving the geometry of the hexad. We predict the cation coordination mode of the two quadruplexes, not yet observed experimentally, and we offer a rationale for the corresponding binding energies involved. 相似文献
138.
Comparison of four extraction/methylation analytical methods to measure fatty acid composition by gas chromatography in meat 总被引:2,自引:0,他引:2
Juárez M Polvillo O Contò M Ficco A Ballico S Failla S 《Journal of chromatography. A》2008,1190(1-2):327-332
Four different extraction-derivatization methods commonly used for fatty acid analysis in meat (in situ or one-step method, saponification method, classic method and a combination of classic extraction and saponification derivatization) were tested. The in situ method had low recovery and variation. The saponification method showed the best balance between recovery, precision, repeatability and reproducibility. The classic method had high recovery and acceptable variation values, except for the polyunsaturated fatty acids, showing higher variation than the former methods. The combination of extraction and methylation steps had great recovery values, but the precision, repeatability and reproducibility were not acceptable. Therefore the saponification method would be more convenient for polyunsaturated fatty acid analysis, whereas the in situ method would be an alternative for fast analysis. However the classic method would be the method of choice for the determination of the different lipid classes. 相似文献
139.
Chaolong Qin Wanshan Feng YenJu Chu Jong Bong Lee Mattia Berton Sara Bettonte Yeong Yeu Teo Michael J. Stocks Peter M. Fischer Pavel Gershkovich 《Biomedical chromatography : BMC》2020,34(11):e4934
A simple, sensitive and cost-effective HPLC-UV bioanalytical method for determination of lopinavir (LPV) in rat and human plasma was developed and validated. The plasma sample preparation procedure includes a combination of protein precipitation using cold acetonitrile and liquid–liquid extraction with n-hexane–ethyl acetate (7:3, v/v). A good chromatographic separation was achieved with a Phenomenex Gemini column (C18, 150 mm × 2.0 mm, 5 μm) at 40°C with gradient elution, at 211 nm. Calibration curves were linear in the range 10–10,000 ng/mL, with a lower limit of quantification of 10 ng/mL using 100 μL of plasma. The accuracy and precision in all validation experiments were within the criteria range set by the guidelines of the Food and Drug Administration. This method was successfully applied to a preliminary pharmacokinetic study in rats following an intravenous bolus administration of LPV. Moreover, the method was subsequently fully validated for human plasma, allowing its use in therapeutic drug monitoring (TDM). In conclusion, this novel, simple and cost-efficient bioanalytical method for determination of LPV is useful for pharmacokinetic and drug delivery studies in rats, as well as TDM in human patients. 相似文献
140.
Eva E. Stüeken Maria de Castro Liliana Krotz Christopher Brodie Mattia Iammarino Guido Giazzi 《Rapid communications in mass spectrometry : RCM》2020,34(18):e8821