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1.
2.
Katell Fiselier Florian Grundböck Karsten Schön Oliver Kappenstein Karla Pfaff Christoph Hutzler Andreas Luch Koni Grob 《Journal of chromatography. A》2013,1271(1):192-200
So far the majority of the measurements of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) were obtained from on-line high performance liquid chromatography–gas chromatography–flame ionization detection (on-line HPLC–GC–FID). Since this technique is not available in many laboratories, an alternative method with more easily available tools has been developed. Preseparation on a small conventional liquid chromatographic column was optimized to achieve robust separation between the MOSH and the MOAH, but also to keep out the wax esters from the MOAH fraction. This was achieved by mixing a small portion of silica gel with silver nitrate into highly activated silica gel and by adding toluene into the eluent for the MOAH. Toluene was also added to the MOSH fraction to facilitate reconcentration and to serve as a keeper preventing loss of volatiles during solvent evaporation. A 50 μl volume was injected on-column into GC–FID to achieve a detection limit for MOSH and MOAH below 1 mg/kg in most foods. 相似文献
3.
We compare extensive experimental results for the
gravity-driven steady drainage of oil-in-water emulsions with two
theoretical predictions, both based on the assumption of Poiseuille flow.
The first is from standard foam drainage theory,
applicable at low aqueous volume fractions, for which a
correction is derived to account for the effects
of the confinement of the emulsion. The second arises
from considering the permeability of a model porous
medium consisting of solid sphere packings, applicable
at higher aqueous volume fractions. We find quantitative
agreement between experiment and the foam drainage theory at low
aqueous volume fractions. At higher aqueous volume
fractions, the reduced flow rate calculated from the
permeability theory approaches the master curve
of the experimental data. Our experimental data
demonstrates the analogy between the problem of electrical flow and liquid
flow through foams and emulsions. 相似文献
4.
5.
The time-optimal control of a soft spring is discussed. The domain of controllability and the switching locus are described. It is shown that the switching locus changes in a discontinuous manner as the nonlinearity varies continuously.This research was partially supported by the Joint Services Electronics Program, Grant No. (4711) N00014-67-A-0226 ARPA 1129, and by NASA, Grant No. NGR 15-005-021. 相似文献
6.
G. Klein Gertrud Pollauf Marie Krisch Elisabeth Farkass F. Schusta Anneliese Niethammer G. D. Lander C. K. Glycart M. Wagenaar F. Pavelka L. van Itallie A. J. Steenhauer A. L. W. E. van der Veen G. Denigès L. Rosenthaler D. Krüger E. Tschirch H. Tangl R. Fischer F. Stauder F. Dangl L. Kofler H. Hilbck C. Griebel F. Weiß A. Hinrichs L. Klemm O. Mohr H. Alber M. Gläser Th. Morawski und J. A. Rose 《Fresenius' Journal of Analytical Chemistry》1933,91(1-2):48-68
Ohne Zusammenfassung 相似文献
7.
G. Klein Gertrud Pollauf Marie Krisch Elisabeth Farkass F. Schusta Anneliese Niethammer G. D. Lander C. K. Glycart M. Wagenaar F. Pavelka L. van Itallie A. J. Steenhauer A. L. W. E. van der Veen G. Denigès L. Rosenthaler D. Krüger E. Tschirch H. Tangl R. Fischer F. Stauder F. Dangl L. Kofler H. Hilbck C. Griebel F. Weiß A. Hinrichs L. Klemm O. Mohr H. Alber M. Gläser Th. Morawski J. A. Rose 《Analytical and bioanalytical chemistry》1933,91(1-2):48-68
8.
Stephanie B. A. De Beer Alice GlÄttli Johannes Hutzler Nico P. E. Vermeulen Chris Oostenbrink 《Journal of computational chemistry》2011,32(10):2160-2169
4‐Hydroxyphenylpyruvate dioxygenase is a relevant target in both pharmaceutical and agricultural research. We report on molecular dynamics simulations and free energy calculations on this enzyme, in complex with 12 inhibitors for which experimental affinities were determined. We applied the thermodynamic integration approach and the more efficient one‐step perturbation. Even though simulations seem well converged and both methods show excellent agreement between them, the correlation with the experimental values remains poor. We investigate the effect of slight modifications on the charge distribution of these highly conjugated systems and find that accurate models can be obtained when using improved force field parameters. This study gives insight into the applicability of free energy methods and current limitations in force field parameterization. © 2011 Wiley Periodicals, Inc. J Comput Chem 2011 相似文献
9.
Anneliese Niethammer 《Mikrochimica acta》1930,8(1):53-62
Ohne Zusammenfassung 相似文献
10.
Here we developed a highly sensitive, fast and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the detection and analysis of 16 different polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs that have been identified as carcinogens and classified according to their biological potency. Comparison to standard analysis procedures based on gas chromatography-mass spectrometry (GC-MS) instrumentation demonstrated an improved easiness of sample preparation and sensitivity of detection achieved with the new LC-MS/MS method employing an atmospheric pressure photoionization (APPI) source attached to an API 4000 mass spectrometer (LC-APPI-MS/MS). The favorable outcome could be confirmed by analyzing complex mixtures such as certain Standard Reference Materials (SRMs) obtained from the National Institute of Standards & Technology (NIST), i.e., SRM 1975 and SRM 2975, and several diesel exhaust soots provided by the German automobile industry. Certified concentrations of individual analytes provided by NIST not only could be confirmed, but additional extremely potent carcinogens such as several isomeric hexacyclic dibenzopyrenes (DBPs), 5-methylchrysene (5-MC), and others have been detected in these crude samples in a concentration range down to below 1 ng g(-1) raw material. 相似文献