200 research outputs found
Revision of late periprosthetic infections of total hip endoprostheses: pros and cons of different concepts
Many concepts have been devised for the treatment of late periprosthetic infections of total hip prostheses. A two-stage revision with a temporary antibiotic-impregnated cement spacer and a cemented prosthesis appears to be the most preferred procedure although, in recent times, there seems to be a trend towards cementless implants and a shorter period of antibiotic treatment. Because of the differences in procedure, not only between studies but also within studies, it cannot be decided which period of parenteral antibiotic treatment and which spacer period is the most suitable. The fact that comparable rates of success can be achieved with different treatment regimens emphasises the importance of surgical removal of all foreign materials and the radical debridement of all infected and ischaemic tissues and the contribution of these crucial procedures to the successful treatment of late periprosthetic infections
Electron Energy-Loss Spectroscopy: A versatile tool for the investigations of plasmonic excitations
The inelastic scattering of electrons is one route to study the vibrational
and electronic properties of materials. Such experiments, also called electron
energy-loss spectroscopy, are particularly useful for the investigation of the
collective excitations in metals, the charge carrier plasmons. These plasmons
are characterized by a specific dispersion (energy-momentum relationship),
which contains information on the sometimes complex nature of the conduction
electrons in topical materials. In this review we highlight the improvements of
the electron energy-loss spectrometer in the last years, summarize current
possibilities with this technique, and give examples where the investigation of
the plasmon dispersion allows insight into the interplay of the conduction
electrons with other degrees of freedom
Plasmons and Interband Transitions of CaSrCuO investigated by Electron Energy-Loss Spectroscopy
Electron energy-loss spectroscopy studies have been performed in order to get
a deeper insight into the electronic structure and elementary excitations of
the two-leg ladder system CaSrCuO. We find a strong
anisotropy of the loss function for momentum transfers along the a and
c-crystallographic axis, and a remarkable linear plasmon dispersion for a
momentum transfer parallel to the legs of the ladders. The investigated
spectral features are attributed to localized and delocalized charge-transfer
excitations and the charge carrier plasmon. The charge carrier plasmon position
and dispersion in the long wave-length limit agree well with expectations based
upon the band structure of the two-leg ladder, while the observed quasi-linear
plasmon dispersion might be related to the peculiar properties of underdoped
cuprates in general.Comment: 16 pages, 8 figure
Signatures of electronic polarons in LaSrMnO observed by electron energy-loss spectroscopy
The dielectric properties of LaSrMnO single crystals with
x = 0, 0.125, 0.25, and 0.5 were studied by means of electron energy-loss
spectroscopy as a function of temperature and momentum transfer. A clear
signature of the doped holes is observed around 1.65 eV energy loss, where
spectral weight emerges with increasing x. For all , this
doping-induced excitation can propagate within the ab-plane, as revealed by a
clear upward dispersion of the corresponding loss peak with increasing momentum
transfer. The hole-induced excitation also shifts to higher energies with the
onset of magnetic correlations for x = 0.5, implying a strong coupling of
charge and spin dynamics. We conclude that (i) the loss feature at 1.65 eV is a
signature of electronic polarons, which are created around doped holes, and
that (ii) this low-energy excitation involves the charge transfer between
manganese and oxygen. The finite dispersion of these excitations further
indicates significant polaron-polaron interactions.Comment: 7 pages, 4 figure
Dextran sulfate activates contact system and mediates arterial hypotension via B2 kinin receptors
To define some of the mechanisms underlying dextran sulfate (DXS)-induced hypotension, we investigated the effects of either the plasma kallikrein inhibitor des-Pro2-[Arg15] aprotinin (BAY x 4620) or the specific bradykinin B2-receptor antagonist Hoe-140 on the hypotensive response to DXS. In the first study, anesthetized miniature pigs were given DXS alone, DXS plus BAY x 4620 in various doses, or saline. As expected, DXS alone produced a profound but transient systemic arterial hypotension with a concomitant reduction in kininogen. Circulating kinin levels, complement fragment des-Arg-C3a, and fibrin monomer were all increased. Treatment with BAY x 4620 produced a dose-dependent attenuation of these effects with complete blockade of the hypotension as well as the observed biochemical changes at the highest dose (360 mg). In a second study, two groups of pigs were given either DXS alone or DXS plus Hoe-140. DXS-induced hypotension was completely blocked by Hoe-140 pretreatment; however, kininogen was again depleted. We conclude, therefore, that DXS-induced hypotension is produced by activation of plasma kallikrein that results in the production of bradykinin and that liberation of bradykinin and its action on B2 receptors in the vasculature are both necessary and sufficient to produce the observed effects on circulatory pressure
Evidence for an orbital dependent Mott transition in the ladders of (La,Ca)SrCuO derived by electron energy-loss spectroscopy
The knowledge of the charge carrier distribution among the different orbitals
of Cu and O is a precondition for the understanding of the physical properties
of various Cu-O frameworks. We employ electron energy-loss spectroscopy to
elucidate the charge carrier plasmon dispersion in (La,
Ca)SrCuO in dependency of as well as
temperature. We observe that the energy of the plasmon increases upon
increasing Ca content, which signals an internal charge redistribution between
the two Cu-O subsystems. Moreover, contrary to an uncorrelated model we come to
the conclusion that the holes transferred to the CuO ladders are mainly
located in the bonding and not in the anti-bonding band. This is caused by an
orbital dependent Mott transition
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