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S. Sterk Frederike van Tricht Anneke van Soeren-Kieft H. Herbold Rainer Stephany Leendert van Ginkel 《Analytical and bioanalytical chemistry》1998,360(3-4):454-455
From three species of livestock, bovine, ovine and porcine, samples of urine from each 10–20 different animals were collected. The animals originated from a governmental experimental farm and differed in race, age, sex and were fed with different types of feed. Fifty different samples of urine were lyophilised in units of 5 mL in sealed amber glass bottles. After lyophilisation of the samples, several quality control tests were performed. The variation in net weight of the units of urine and the lyophilisates ranged from 0.01%–1.7% and 0.1%–10%, respectively. Most values did not exceed 0.1% for urines and 1% for lyophilisates. The residual water content of the lyophilisates was determined by the Karl-Fisher titration method. The average percentage of residual water ranged from 1.0%–7.0% for bovine, from 1.3%–3.0% for porcine and from 1.6%–5.5% for ovine urine lyophilisates. Further, all different samples were analysed for the presence of anabolic compounds with a multi-residue procedure developed at the CRL. In two samples of bovine urine the presence of α-boldenone was detected and confirmed. In most porcine urines the endogenous steroids α-testosterone and α-estradiol were detected. In a number of porcine and ovine urine samples α- and β-zearalenol were detected. The origin of these compounds is the f2-toxin produced by a Fusarium fungus. In ovine samples α-testosterone and α-estradiol were detected. 相似文献
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Dr. Tim Schleif Dr. Jörg Tatchen Julien F. Rowen Frederike Beyer Prof. Dr. Elsa Sanchez-Garcia Prof. Dr. Wolfram Sander 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(46):10452-10458
The Cope rearrangement of selectively deuterated isotopomers of 1,5-dimethylsemibullvalene 2 a and 3,7-dicyano-1,5-dimethylsemibullvalene 2 b were studied in cryogenic matrices. In both semibullvalenes the Cope rearrangement is governed by heavy-atom tunneling. The driving force for the rearrangements is the small difference in the zero-point vibrational energies of the isotopomers. To evaluate the effect of the driving force on the tunneling probability in 2 a and 2 b , two different pairs of isotopomers were studied for each of the semibullvalenes. The reaction rates for the rearrangement of 2 b in cryogenic matrices were found to be smaller than the ones of 2 a under similar conditions, whereas differences in the driving force do not influence the rates. Small curvature tunneling (SCT) calculations suggest that the reduced tunneling rate of 2 b compared to that of 2 a results from a change in the shape of the potential energy barrier. The tunneling probability of the semibullvalenes strongly depends on the matrix environment; however, for 2 a in a qualitatively different way than for 2 b . 相似文献
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R. Katajanheimo H. Liljavirta A. Siivola E. Hammarén E. Liukkonen 《Zeitschrift für Physik A Hadrons and Nuclei》1984,319(1):91-96
Excited states in the nucleus155Eu have been produced during in-beam bombardments of a154Sm target with3He beams at 22 and 27 MeV. Decay gamma rays were detected using coincidence equipment optimized for low-energy photons. The level scheme is based on the observedγγ-coincidence relationships combined with the information on relative intensities. Tentatively suggested spin assignments follow from the apparent rotational character of the nucleus. Experimental observations are compared with predictions calculated from a particle-rotor model with a nonspheroidal Woods-Saxon potential. 相似文献
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Hartree-Fock-Bogoliubov calculations with spin and number projection before the variation (VAMPIR) are performed for the nuclei 128Ba and 130Ce using a slightly renormalized Brueckner G-matrix as effective interaction in a rather large single-particle basis. The results are compared to those of Hartree-Fock-Bogoliubov calculations with projection after the variation, those of multiconfiguration calculations (MONSTER) and to experiment. In both nuclei the VAMPIR and the MONSTER approaches turn out to be of about the same quality and agree rather well with the experimental data. Analysis of the VAMPIR mean fields reveals that two somewhat different mechanisms are responsible for the backbending observed in the yrast bands of the two nuclei. While in 130Ce the well-known alignment of two high-j quasiparticles (proton ) is found, in 128Ba first a neutron pair is scattered from the to the orbit, and then the larger alignment energy of the less occupied neutron states produces the backbend. This latter effect is in agreement with the predictions of a simple model presented by us some years ago. 相似文献
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C. Hammar 《Physics letters. A》1973,45(4):329-330
By changing the mobility anisotropy between non-equivalent minima in the conduction band of n-Ge a magnetic field in the [110] direction can induce a negative resistance at temperatures below 20–30 K. 相似文献
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