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401.
Marques Lde A Catharino RR Bruns RE Eberlin MN 《Rapid communications in mass spectrometry : RCM》2006,20(24):3654-3658
A fast procedure to classify perfumes and identify counterfeit samples is described. Dilution of a few microL of the sample in a 1:1 methanol/water solution is followed by detection of its major polar components via direct infusion electrospray ionization mass spectrometry (ESI-MS) in the positive ion mode. As proof-of-principle cases, three famous brands of perfumes were used. The ESI+-MS fingerprints of authentic samples were very characteristic, showing distinctive sets of polar markers for each sample. Principal component analysis (PCA) placed samples of the three perfume brands in well-defined groups. Counterfeit samples were also clearly detected owing to contrasting ESI-MS fingerprints, with PCA placing these samples far away from the authentic samples. 相似文献
402.
Moreira RF Salvadori MC Azevedo CP Oliveira-Silva D Borges DC Moreno RA Sverdloff CE Borges NC 《Biomedical chromatography : BMC》2010,24(11):1220-1227
The validation of a high throughput and specific method using a high‐performance liquid chromatography coupled to electrospray (ES+) ionization tandem triple quadrupole mass spectrometric (LC‐ESI‐MS/MS) method for ondansetron quantification in human plasma is described. Human plasma samples were extracted by liquid–liquid extraction (LLE) using methyl tert‐butyl ether and analyzed by LC‐ESI‐MS/MS. The limit of quantification was 0.2 ng/mL and the method was linear in the range 0.2–60 ng/mL. The intra‐assay precisions ranged from 1.6 to 7.7%, while inter‐assay precisions ranged from 2.1 to 5.1%. The intra‐assay accuracies ranged from 97.5 to 108.2%, and the inter‐assay accuracies ranged from 97.3 to 107.0%. The analytical method was applied to evaluate the relative bioavailability of two pharmaceutical formulations containing 8 mg of ondansetron each in 25 healthy volunteers using a randomized, two‐period crossover design. The geometric mean and respective 90% confidence interval (CI) of ondansetron test/reference percent ratios were 90.15% (81.74–99.44%) for Cmax and 93.11% (83.01–104.43%) for AUC0–t. Based on the 90% confidence interval of the individual ratios (test formulation/reference formulation) for Cmax and AUC0‐inf, it was concluded that the test formulation is bioequivalent to the reference one with respect to the rate and extent of absorption of ondansetron. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
403.
A. Freitas S. Azevedo M. Machado J. R. Kaschny 《Applied Physics A: Materials Science & Processing》2012,108(1):185-193
In this work, we apply first-principles methods to investigate the stability and electronic structure of BC4N nanostructures which were constructed from hexagonal graphite layers where substitutional nitrogen and boron atoms are placed at specific sites. These layers were rolled up to form zigzag and armchair nanotubes, with diameters varying from 7 to 12 Å, or cut and bent to form nanocones, with 60° and 120° disclination angles. The calculation results indicate that the most stable structures are the ones which maximize the number of B–N and C–C bonds. It is found that the zigzag nanotubes are more stable than the armchair ones, where the strain energy decreases with increasing tube diameter D, following a 1/D 2 law. The results show that the 60° disclination nanocones are the most stable ones. Additionally, the calculated electronic properties indicate a semiconducting behavior for all calculated structures, which is intermediate to the typical behaviors found for hexagonal boron nitride and graphene. 相似文献
404.
Azevedo Celsina N. Gonçalves Victor P. Moreira Bruno D. 《The European Physical Journal A - Hadrons and Nuclei》2023,59(2):1-13
The European Physical Journal A - We give an overview of the special challenges regarding target development and production for accelerator-based heavy and superheavy-nuclei experiments in the past... 相似文献
405.
José Vanterler da C. Sousa Gastão S. F. Frederico Daniela S. Oliveira Edmundo Capelas de Oliveira 《Mathematical Methods in the Applied Sciences》2023,46(1):930-960
This paper is divided into two stages. In the first stage, we investigated a new approach for the -Riemann–Liouville fractional integral and the Faa di Bruno formula for the -Hilfer fractional derivative. In addition, we discussed other properties involving the -Hilfer fractional derivative and the -Riemann–Liouville fractional integral. In the second stage, Bernstein polynomials involving the function are investigated and the -Riemann–Liouville fractional integral and -Hilfer fractional derivative from the Bernstein polynomials are evaluated. We also discussed the relationship between the -Hilfer fractional derivative with Laguerre polynomials and hypergeometric functions, and a version of the fractional mean value theorem with respect to a function. Motivated by the Bernstein polynomials, the second stage uses the Bernstein polynomials to approximate the solution of a fractional integro-differential equation with Hilfer fractional derivative and concluding with a numerical approach with its respective graph. 相似文献