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1.
Characterisation of fatty acids in biological oil samples using comprehensive multidimensional gas chromatography 总被引:1,自引:0,他引:1
Comprehensive multidimensional gas chromatography can adequately resolve very complex mixtures of analytes such as the fatty acid mixtures which are contained in, e.g., fish and vegetable oils. Well-ordered patterns are obtained in the two-dimensional separation plane which can be used to tentatively identify peaks when no standard is available. The technique which can also be used for quantification, i.e., quantitative ratio analysis, should be especially useful for fingerprinting purposes. Unravelling the composition of complex mixtures such as fish oils appears to be highly rewarding. 相似文献
2.
3.
Vink MK Schortinghuis CA Luten J Van Maarseveen JH Schoemaker HE Hiemstra H Rutjes FP 《The Journal of organic chemistry》2002,67(22):7869-7871
A stereodivergent route toward both diastereomeric forms of functionalized 4-hydroxypiperidines has been successfully developed. This route involves biocatalytic generation of the enantiopure starting materials followed by functionalization via N-acyliminium ion-mediated CC-bond formation. 相似文献
4.
Donato Ercole Conte Abdelmaula Aboulaich Josette Olivier-Fourcade Christian Jordy 《Journal of solid state chemistry》2010,183(1):65-6650
A comparative study of two Sn-based composite materials as negative electrode for Li-ion accumulators is presented. The former SnB0.6P0.4O2.9 obtained by in-situ dispersion of SnO in an oxide matrix is shown to be an amorphous tin composite oxide (ATCO). The latter Sn0.72[BPO4]0.28 obtained by ex-situ dispersion of Sn in a borophosphate matrix consists of Sn particles embedded in a crystalline BPO4 matrix. The electrochemical responses of ATCO and Sn0.72[BPO4]0.28 composite in galvanostatic mode show reversible capacities of about 450 and 530 mAh g−1, respectively, with different irreversible capacities (60% and 29%). Analysis of these composite materials by 119Sn Mössbauer spectroscopy in transmission (TMS) and emission (CEMS) modes confirms that ATCO is an amorphous SnII composite oxide and shows that in the case of Sn0.72[BPO4]0.28, the surface of the tin clusters is mainly formed by SnII in an amorphous interface whereas the bulk of the clusters is mainly formed by Sn0. The determination of the recoilless free fractions f (Lamb-Mössbauer factors) leads to the effective fraction of both Sn0 and SnII species in such composites. The influence of chemical composition and especially of the surface-to-bulk tin species ratio on the electrochemical behaviour has been analysed for several Snx[BPO4]1−x composite materials (0.17<x<0.91). The cell using the compound Sn0.72[BPO4]0.28 as active material exhibits interesting electrochemical performances (reversible capacity of 500 mAh g−1 at C/5 rate). 相似文献
5.
We study the conjecture of Jarque and Villadelprat stating that every center of a planar polynomial Hamiltonian system of even degree is nonisochronous. This conjecture has already been proved for quadratic and quartic systems. Using the correction of a vector field to characterize isochronicity and explicit computations of this quantity for polynomial vector fields, we are able to describe a very large class of nonisochronous Hamiltonian systems of even arbitrarily large degree. 相似文献
6.
J. B. Luten J. R. W. Woittiez H. A. Das C. L. De Ligny 《Journal of Radioanalytical and Nuclear Chemistry》1978,43(1):175-185
The determination of iodate in rain-water by neutron activation analysis is described. Iodate is separated by anion exchange.
The determination limit of I is 0.02 μg·L−1 for a 20 ml sample. The influence of the sea on the composition of rain-water is demonstrated by the analysis of coastal
rain-water. The results indicate that inorganic iodine (I2 and IO
3
−
) is enriched in filtered coastal rain-water relative to the composition of sea-water. 相似文献
7.
Jordy de Vries 《Hyperfine Interactions》2013,214(1-3):79-86
I present the calculation of parity- and time-reversal-violating moments of the nucleon and light nuclei, originating from the QCD $\bar \theta$ term and effective dimension-six operators. By applying chiral effective field theory these calculations are performed in a unified framework. I argue that measurements of a few light-nuclear electric dipole moments would shed light on the mechanism of parity and time-reversal violation. 相似文献
8.
M. Ménétrier L. Croguennec A. Flambard C. Jordy C. Delmas 《Journal of solid state chemistry》2008,181(12):3303-3307
A series of “Li1+z/2(Ni0.425Mn0.425Co0.15)1−z/2O2−zFz” materials was prepared by a coprecipitation route and their structure was characterized using X-ray diffraction (XRD), as well as 7Li and 19F Magic Angle Spinning (MAS) NMR spectroscopy. Two hypotheses were considered: (i) formation of layered oxyfluoride materials and (ii) formation of a mixture between the layered material and LiF. Structural parameters were refined by the Rietveld method, using XRD diffraction data. The refinement results did not allow us to choose between these two hypotheses: no significant change in crystallinity and structural parameters was observed irrespective of the fluorine ratio. 7Li and 19F MAS NMR analyses showed signals with isotropic positions characteristic of LiF, but envelopes characteristic of very strong dipolar interactions with the electron spins of the material, demonstrating that LiF was not incorporated into the layered oxide structure but was instead present as a coating. 相似文献
9.
J. B. Luten H. A. Das C. L. De Ligny 《Journal of Radioanalytical and Nuclear Chemistry》1977,35(1):147-155
A routine-method for the determination of bromine and iodine in environmental water by neutron activation is presented. The
elements are isolated by isotope exchange between the irradiated sample and a solution of Br2 or I2 CCl4. The method is not sensitive to the chemical species in which the halogen is present. The lower limit of the determination
is 1.0 μg Br·1−1 and 0.1 μgI·1−1. 相似文献
10.
The reactions of the ethynyl radical (C(2)H) with ethene (C(2)H(4)) and propene (C(3)H(6)) are studied under low temperature conditions (79 K) in a pulsed Laval nozzle apparatus. Ethynyl radicals are formed by 193 nm photolysis of acetylene (C(2)H(2)) and the reactions are studied in nitrogen as a carrier gas. Reaction products are sampled and subsequently photoionized by the tunable vacuum ultraviolet radiation of the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. The product ions are detected mass selectively and time-resolved by a quadrupole mass spectrometer. Bimolecular rate coefficients are determined under pseudo-first-order conditions, yielding values in good agreement with previous measurements. Photoionization spectra are measured by scanning the ALS photon energy while detecting the ionized reaction products. Analysis of the photoionization spectra yields-for the first time-low temperature isomer resolved product branching ratios. The reaction between C(2)H and ethene is found to proceed by H-loss and yields 100% vinylacetylene. The reaction between C(2)H and propene results in (85 ± 10)% C(4)H(4) (m/z = 52) via CH(3)-loss and (15 ± 10)% C(5)H(6) (m/z = 66) by H-loss. The C(4)H(4) channel is found to consist of 100% vinylacetylene. For the C(5)H(6) channel, analysis of the photoionization spectrum reveals that (62 ± 16)% is in the form of 4-penten-1-yne, (27 ± 8)% is in the form of cis- and trans-3-penten-1-yne and (11 ± 10)% is in the form of 2-methyl-1-buten-3-yne. 相似文献