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Katarzyna Bielicka‐Daszkiewicz Adam Voelkel Danuta Rusińska‐Roszak Paweł K. Zarzycki 《Journal of separation science》2013,36(6):1104-1111
SPE method is a very popular technique, and is commonly used for the prepurification, concentration, and isolation of different organic compounds from variable matrices. In this work, the optimization of SPE process was carried out. The breakthrough volume of solid sorbents based on octadecylsilane was determined and three methods were compared: (1) calculation one – the breakthrough volume was calculated using retention factor k determined with micro‐TLC method, frontal analysis – (2) breakthrough volume was determined as volume of whole elution peak, and (3) breakthrough volume was determined as the center of peak gravity. For calculation method, the k values of key estrogens and progestogens were derived from the micro‐TLC experiment reported previously. By combining these three methods, we can point the start of elution, the maximum concentration of analyte in eluate, and the whole eluent volume, which is necessary to achieve an appropriate selectivity and high extraction recovery. Proposed calculation method allows to estimate the beginning of the steroid peak, when the analyte appears in the eluate flowing from the sorbent. Such observation advances the SPE optimization protocol that was described before and was based on the correlation between raw kSPE and kmicro‐TLC data. 相似文献
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Journal of Analytical Chemistry - Lithium iron phosphate materials as one of the most representative cathode materials for lithium-ion battery were found to possess intrinsic peroxidase-like... 相似文献
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R. Cierpiszewski D. Rusińska-Roszak J. Szymanowski W. Mickler E. Uhlemann 《Journal of Radioanalytical and Nuclear Chemistry》1998,228(1-2):71-76
The rate of copper extraction with individual 4-acyl-5-pyrazolones and the stability of various enolic and keto forms and their monohydrates were studied. The rate of extraction depends mainly upon the structure of substituent at position 4 and falls when the substituent becomes spacy. The effect of the substituent at position 1 is rather low. The enolic form with intramolecular hydrogen bonding is the most stable. It can form hydrates with water molecules without intramolecular hydrogen bond breaking. 相似文献
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H.-Ch. Schröder A. Badertscher P.F.A. Goudsmit M. Janousch H.J. Leisi E. Matsinos D. Sigg Z.G. Zhao D. Chatellard J.-P. Egger K. Gabathuler P. Hauser L.M. Simons A.J. Rusi El Hassani 《The European Physical Journal C - Particles and Fields》2001,21(3):473-488
This is the final publication of the ETH Zurich–Neuchatel–PSI collaboration on the pionic hydrogen and deuterium precision
X-ray experiments. We describe the recent hydrogen 3p–1s measurement, report on the determination of the Doppler effect correction to the transition line width, analyze the deuterium
shift measurement and discuss implications of the combined hydrogen and deuterium results. From the pionic hydrogen 3p–1s transition experiments we obtain the strong-interaction energy level shift eV and the total decay width eV of the state. Taking into account the electromagnetic corrections we find the hadronic
s-wave scattering amplitude for elastic scattering and for single charge exchange, respectively. We then combine the pionic hydrogen results with the 1s level shift measurement on pionic deuterium and test isospin symmetry of the strong interaction: our data are still compatible
with isospin symmetry. The isoscalar and isovector scattering lengths (within the framework of isospin symmetry) are found to be and , respectively. Using the GMO sum rule, we obtain from a new value of the coupling constant () from which follows the Goldberger–Treiman discrepancy . The new values of and imply an increase of the nucleon sigma term by at least 9 MeV.
Received: 20 April 2001 / Revised version: 6 July 2001 / Published online: 24 August 2001 相似文献
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Density functional molecular dynamics simulations have been performed in the NVT ensemble (moles (N), volume (V) and temperature (T)) on a system formed by ten acetone molecules at a temperature of 2000 K and density ρ = 1.322 g cm(-3). These conditions resemble closely those realized at the interface of an acetone vapor bubble in the early stages of supercompression experiments and result in an average pressure of 5 GPa. Two relevant reactive events occur during the simulation: the condensation of two acetone molecules to give hexane-2,5-dione and dihydrogen and the isomerization to the enolic propen-2-ol form. The mechanisms of these events are discussed in detail. 相似文献
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Polyaniline (PANI) nanowire electrode was successfully prepared using electrodeposition method. The morphology, thickness, and electrochemical performance of PANI electrode can be controlled by varying the deposition scan rates. Lower deposition scan rate results in compact and aggregates of PANI nanowire morphology. The uniform nanowire of PANI was obtained at the applied scan rate of 100 mV s?1, and it was used as symmetric electrode coupled with H2SO4/polyvinyl alcohol (PVA) gel electrolyte. The different concentrations of H2SO4 acid in polymer electrolyte have influenced the electrochemical performance as well. The optimum specific capacitance and energy density of P100 PANI electrode in 3 M H2SO4/PVA gel polymer electrolyte was 377 F g?1 and 95.4 Wh kg?1 at the scan rate of 1 mV s?1. The good stability of the electrode in this system is applicable to many wearable electronics applications. 相似文献
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D. Barb L. Diamandescu D. Mihăilă-Tărăbăsanu A. Rusi M. Morariu 《Hyperfine Interactions》1990,53(1-4):285-289
The reaction kinetics of the hydrothermal transformation -FeOOH-Fe2O3 was studied by means of Mössbauer spectroscopy. From the reaction isotherms, a monomolecular, first order reaction was found to characterise the hydrothermal transformation of alpha oxihydroxide to the alpha iron oxide. The rate constant as well as the activation energy of this process were determined. No intermediate phases were identified in the hydrothermal samples. The thermodynamic properties of the hydrothermal system -FeOOH-Fe2O3 in correlation with Mössbauer spectroscopy data are discussed. 相似文献