123 research outputs found
Explaining the magnetic moment reduction of Fullerene encapsulated Gadolinium through a theoretical model
We propose a Theoretical model accounting for the recently observed reduced
magnetic moment of Gadolinium in fullerenes. While this reduction has been
observed also for other trivalent rare-hearth atoms (Dy3+, Er3+, Ho3+) in
fullerenes and can be ascribed to crystal field effects, the explanation of
this phenomena for Gd3+ is not straightforward due to the sphericity of its
ground state (S=7/2, L=0). In our model the momentum lowering is the result of
a subtle interplay between hybridisation and spin-orbit interaction
Private Strafvollzugsanstalten in den USA: eine Perspektive für Deutschland?
'Bedingt durch eine Vielzahl von Faktoren, wie wachsende Gefangenenzahlen, überfüllte Haftanstalten und steigende Vollzugskosten sind in den USA in den vergangenen zwanzig Jahren privat geführte Stratvollzugsanstalten entstanden. Heute geht man von einem Anteil von etwa 5% privater Haftplätze im Strafvollzugssystem aus. Auch in Deutschland sind zunehmend Privatisierungstendenzen im Bereich der Sozialkontrolle zu verzeichnen. Dieses Buch befasst sich einerseits mit den Faktoren, die in den USA einer Privatisierung Vorschub geleistet haben und untersucht andererseits parallele Entwicklungen in Deutschland. Möglichkeiten und Grenzen einer Privatisierung Im Strafvollzug In Deutschland werden unter rechtlichen Gesichtspunkten ausgelotet und vor dem Hintergrund eines sich wandelnden Staatsverständnisses diskutiert.' (Autorenreferat
Pressure-induced changes of the vibrational modes of spin-crossover complexes studied by nuclear resonance scattering of synchrotron radiation
Nuclear inelastic scattering (NIS) spectra were recorded for the
spin-crossover complexes STP and ETP (STP =
[Fe(1,1,1-trisf[N-(2-pyridylmethyl)-N-methylamino]methylg- ethane)](ClO4)2 and
ETP =
[Fe(1,1,1-trisf[N-(2-pyridylmethyl)-N-methylamino]methylg-butane)](ClO4)2) at
30 K and at room temperature and also at ambient pressure and applied pressure
(up to 2.6 GPa). Spin transition from the high-spin (HS) to the low-spin (LS)
state was observed by lowering temperature and also by applying pressure at
room temperature and has been assigned to the hardening of iron-bond stretching
modes due to the smaller volume in the LS isomer
Grüneisen parameter of hcp‐Fe to 171 GPa
We measured the phonon density of states (DOS) of hexagonal close-packed iron (ɛ-Fe) with high statistical quality using nuclear resonant inelastic X-ray scattering and in situ X-ray diffraction experiments between pressures of 30 GPa and 171 GPa and at 300 K, with a neon pressure medium up to 69 GPa. The shape of the phonon DOS remained similar at all compression points, while the maximum (cutoff) energy increased regularly with decreasing volume. As a result, we present a generalized scaling law to describe the volume dependence of ɛ-Fe's total phonon DOS which, in turn, is directly related to the ambient temperature vibrational Grüneisen parameter (γ_(vib)). Fitting our individual γ_(vib) data points with γ_(vib) = γ_(vib),0(V/V0)^q, a common parameterization, we found an ambient pressure γ_(vib,0) = 2.0 ± 0.1 for the range q = 0.8 to 1.2. We also determined the Debye sound velocity (v_D) from the low-energy region of the phonon DOS and our in situ measured volumes, and used the volume dependence of v_D to determine the commonly discussed Debye Grüneisen parameter (γ_D). Comparing our γ_(vib)(V) and γ_D(V), we found γ_(vib) to be ∼10% larger than γ_D at any given volume. Finally, applying our γ_(vib)(V) to a Mie-Grüneisen type relationship and an approximate form of the empirical Lindemann melting criterion, we predict the vibrational thermal pressure and estimate the high-pressure melting behavior of ɛ-Fe at Earth's core pressures
Ethics of primate use
This article provides an overview of the ethical issues raised by the use of
non-human primates (NHPs) in research involving scientific procedures which
may cause pain, suffering, distress or lasting harm. It is not an exhaustive
review of the literature and views on this subject, and it does not present
any conclusions about the moral acceptability or otherwise of NHP research.
Rather the aim has been to identify the ethical issues involved and to
provide guidance on how these might be addressed, in particular by carefully
examining the scientific rationale for NHP use, implementing fully the 3Rs
principle of Russell and Burch (1959) and applying a robust "harm-benefit
assessment" to research proposals involving NHPs
Ce-L3-XAS study of the temperature dependence of the 4f occupancy in the Kondo system Ce2Rh3Al9
We have used temperature dependent x-ray absorption at the Ce-L3 edge to
investigate the recently discovered Kondo compound Ce2Rh3Al9. The systematic
changes of the spectral lineshape with decreasing temperature are analyzed and
found to be related to a change in the occupation number, n_f, as the
system undergoes a transition into a Kondo state. The temperature dependence of
indicates a characteristic temperature of 150K, which is clearly related
with the high temperature anomaly observed in the magnetic susceptibility of
the same system. The further anomaly observed in the resistivity of this system
at low temperature (ca. 20K) has no effect on n_f and is thus not of Kondo
origin.Comment: 7 pages, three figures, submitted to PR
Elastic and vibrational properties of alpha and beta-PbO
The structure, electronic and dynamic properties of the two layered alpha
(litharge) and beta (massicot) phases of PbO have been studied by density
functional methods. The role of London dispersion interactions as leading
component of the total interaction energy between layers has been addressed by
using the Grimme's approach, in which new parameters for Pb and O atoms have
been developed. Both gradient corrected and hybrid functionals have been
adopted using Gaussian-type basis sets of polarized triple zeta quality for O
atoms and small core pseudo-potential for the Pb atoms. Basis set superposition
error (BSSE) has been accounted for by the Boys-Bernardi correction to compute
the interlayer separation. Cross check with calculations adopting plane waves
that are BSSE free have also been performed for both structures and vibrational
frequencies. With the new set of proposed Grimme's type parameters structures
and dynamical parameters for both PbO phases are in good agreement with
experimental data.Comment: 8 pages, 5 figure
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