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101.
Dynamic force spectroscopy of conservative and dissipative forces in an Al-Au(111) tip-sample system
The conservative and dissipative interaction between an aluminum tip and a gold (111) surface were investigated using dynamic force spectroscopy in UHV. Complete force vs distance curves and friction coefficient vs distance curves were obtained quantitatively. The force curves were compared to the model by Muller, Yushenko, and Derjaguin, and long and short range interactions were subsequently quantified without fit parameters. A short range conservative interaction was separated from longer range van der Waals forces. The long range behavior of the damping coefficient obeys an inverse power law of third order. 相似文献
102.
Radtke R Biedermann C Fuchs T Fussmann G Beiersdorfer P 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(2):1966-1974
We describe a measurement of the radiative cooling rate for krypton made at the Berlin electron beam ion trap (EBIT). The EBIT was tuned to a charge-state distribution approaching the ionization balance of a plasma at a temperature of about 5 keV. To determine the cooling rate, we made use of EBIT's capabilities to sample a wide range of electron-beam energies and distinguish between different radiation channels. We have measured the x-ray emission from bremsstrahlung, radiative recombination, dielectronic recombination, and line radiation following electron-impact excitation. The dominant contribution to the cooling rate is made by the n=3-2, n=4-2, ellipsis x rays of the L-shell spectra of krypton, which produce more than 75% of the total radiation loss. A difference with theoretical calculations is noted for the measured total cooling rate. The predicted values are lower by a factor of 1.5-2, depending on the theoretical model. For our measurement of the cooling rate, we estimate an uncertainty interval of 22-30 %. 相似文献
103.
Gerhard Friedrich Thorsten Rose Alexander Wawkuschewski Sabine Kafert-Kasting Britta Laube Lubomir Arseniev Klaus Rissler 《Chromatographia》2008,67(1-2):31-39
In a recently published paper development of a sensitive automated “on-line” solid-phase extraction (SPE)/RP-HPLC assay for
6β-hydroxytestosterone (6β-OHT) with corticosterone as the internal standard (IS) was reported and its potential for quantification
of various testosterone metabolites in culture media reflecting metabolic activity of cultured human and animal hepatocytes
demonstrated [1]. In this following contribution the technique has been extended to determination of another five testosterone metabolites
in cultured rat hepatocytes using an identical “on-line” SPE/RP-HPLC procedure and detection by tandem MS-MS with an atmospheric
pressure chemical ionization (APCI) source in the selected reaction monitoring (SRM) mode as that described in [1]. All six testosterone metabolites, namely 2α-OHT, 2β-OHT, 6α-OHT, 6β-OHT, 7α-OHT and 16α-OHT, could be sufficiently separated
from each other and thus an unequivocal assignment to the individual structures was achieved. Validation data are presented
specifying the limits of quantitation as well as the mean values of the coefficients of variation (CV) for the target analytes
and the accuracy obtained at five different days. Regio- and stereoselective testosterone hydroxylation by rat hepatocytes
was measured in a long-term culture system with and without exposure to rifampicin as an inducer of liver CYP 3A4 activity.
In addition, testosterone hydroxylation was analyzed in cultures of cryopreserved hepatocytes that had been stored at −196 °C.
The rat hepatocytes were cultured after thawing for up to 11 days and induction of testosterone hydroxylase activity could
be demonstrated in cultures which underwent a new cryopreservation protocol.
This paper is dedicated to Professor Hinrich Cramer on the occasion of his 75th birthday. 相似文献
104.
The directed flow of protons is studied in the quark-gluon string model as a function of the impact parameter for S+S and Pb+Pb reactions at 160 AGeV/c. A significant reduction of the directed flow in midrapidity range, which can lead to the development of the antiflow, is found due to the absorption of early emitted particles by massive spectators (shadowing effect). This effect can mimic the formation of the quark-gluon plasma (QGP). However, in the absorption scenario the antiflow is stronger for the system of light colliding nuclei than for the heavy ones, while in the case of the plasma creation the effect should be opposite. 相似文献
105.
L. Fuchs 《Acta Mathematica》1882,1(1):321-362
Ohne Zusammenfassung 相似文献
106.
R. Fuchs S. B. Jost H. Rudin H. -J. Güntherodt P. Fischer 《Zeitschrift für Physik B Condensed Matter》1987,68(2-3):309-311
The structure factors of the amorphous, icosahedral and crystalline Pd58.8U20.6Si20.6 were measured with X-rays and neutrons. By comparing the radial distribution functions of the three phases, we find a similar short range order in the amorphous and icosahedral phase, but a different atomic arrangement in the crystalline phase. A magnetic long range order observed in the crystalline material is absent in the icosahedral phase.Dedicated to Professor Harry Thomas on the occasion of his 60th birthday 相似文献
107.
108.
We investigate the function u
K,S
(n; q) which counts the number of representations of algebraic integers α with
|NK/\mathbb Q(a)| £ q{|N_{K/{\mathbb Q}}(\alpha)| \leq q} for some real positive q that can be written as sums of exactly n
S-units of the number field K. 相似文献
109.
H. Kühl R. Rüter J. Micka K. Vrana C. W. Herd A. J. Amos K. Fuchs W. Ruziczka E. Kohn K. Seidel und D. W. Kent-Jones 《Fresenius' Journal of Analytical Chemistry》1931,84(1-2):57-61
Ohne Zusammenfassung 相似文献
110.
B. M. Margoschcs W. Hinner L. Friedmann K. Fuchs E. Neufeld Mauricy Frischer A. Grün W. Czerny M. Nahptali D. Holdes und deutsche Kommission zur Schaffung einheitlicher Untersuchungsverfahren für die Fettindustrie 《Fresenius' Journal of Analytical Chemistry》1927,72(1-2):64-67
Ohne Zusammenfassung 相似文献