216 research outputs found
A new diluted magnetic semiconductor: The half-metallic ferromagnet CoTi(1-x)FexSb
Half-Heusler compounds with 18 valence electrons are semi-conducting. It will
be shown that doping with electrons results in half-metallic ferromagnets,
similar to the case of diluted semi-conductors. CoTiSb is known to be a
semi-conducting Half-Heusler compound. Doping by Fe is expected to result in
ferromagnetic order. It was found that Ti can be replaced by up to about 10% Fe
while its crystal structure still remains C1b, which was proved by X-ray powder
diffraction. SQUID magnetometry revealed a magnetic moment of 0.32 mB per unit
cell at 5K.Comment: JMMM accepte
Internationale Hochschulrankings: Ein methodenkritischer Vergleich
Zusammenfassung: Trotz ihrer umstrittenen Validität, Zuverlässigkeit und Wirkung, werden internationale Universitätsrankings immer häufiger von Studierenden und Universitäten als Informationsquellen genutzt. Dieser Artikel vergleicht drei internationale Hochschulrankings und analysiert, basierend auf der wissenschaftlichen Literatur, inwiefern sie relevante Aspekte von Forschung oder Lehre erheben und diese adäquat und verlässlich messen. Untersucht wurden das Academic Ranking of World Universities (ARWU Ranking), das World University Ranking und das vom deutschen Centrum für Hochschulentwicklung (CHE) entwickelte Excellence Ranking für Master- und Doktorandenprogramme. Die Analyse basiert auf den Publikationen der Herausgeber der Rankings und auf wissenschaftlichen Artikeln über diese internationalen Rankings. Basierend auf der Analyse werden Schlussfolgerungen für die Gestaltung internationaler Rankings abgeleitet und weiterführende Forschungsfragen formulier
Bulk sensitive photo emission spectroscopy of C1b compounds
This work reports about bulk-sensitive, high energy photoelectron
spectroscopy from the valence band of CoTiSb excited by photons from 1.2 to 5
keV energy. The high energy photoelectron spectra were taken at the KMC-1 high
energy beamline of BESSY II employing the recently developed Phoibos 225 HV
analyser. The measurements show a good agreement to calculations of the
electronic structure using the LDA scheme. It is shown that the high energy
spectra reveal the bulk electronic structure better compared to low energy XPS
spectra.Comment: J. Electron Spectrosc. Relat. Phenom. accepte
Electronic structure and spectroscopy of the quaternary Heusler alloy CoCrFeAl
Quaternary Heusler alloys CoCrFeAl with varying Cr to Fe
ratio were investigated experimentally and theoretically. The electronic
structure and spectroscopic properties were calculated using the full
relativistic Korringa-Kohn-Rostocker method with coherent potential
approximation to account for the random distribution of Cr and Fe atoms as well
as random disorder. Magnetic effects are included by the use of spin dependent
potentials in the local spin density approximation.
Magnetic circular dichroism in X-ray absorption was measured at the
edges of Co, Fe, and Cr of the pure compounds and the alloy in order to
determine element specific magnetic moments. Calculations and measurements show
an increase of the magnetic moments with increasing iron content. Resonant
(560eV - 800eV) soft X-ray as well as high resolution - high energy (keV) hard X-ray photo emission was used to probe the density of the
occupied states in CoCrFeAl.Comment: J.Phys.D_Appl.Phys. accepte
Conformational studies of stereoisomeric tetraols serived form syn- and anti-dibenzo [a,l]pyrene diolepoxides
An understanding of the conformational behavior of the stereoisomeric tetrols at the 11,12,13,14-positions of dibenzo[a,l]pyrene (DB[a,l]P) is essential for the spectroscopic identification of DNA adducts derived from the biologically highly active fjord region syn- and anti-DB[a,l]P-11,12- diol 13,14-epoxides. Conformational effects are expected to play an important role in DNA-DB[a,l]P diol epoxide reactivity, base-sequence specificity, and conformation dependent repair. The results of conformational studies on trans-anti-, cis-anti-, and cis-syn-DB[a,l]P tetrol isomers are presented and compared to the results obtained previously for trans-syn-DB[a,l]P tetrol (Carcinogenesis 17, 829-837, 1996). Molecular mechanics, dynamical simulations, and semiempirical calculations of electronic transitions are used to interpret the low-temperature fluorescence spectra an
Mitochondrial glycolysis in a major lineage of eukaryotes
This is the author accepted manuscript. The final version is freely available from OUP via the DOI in this recordThe establishment of the mitochondrion is seen as a transformational step in the origin of eukaryotes. With the mitochondrion came bioenergetic freedom to explore novel evolutionary space leading to the eukaryotic radiation known today. The tight integration of the bacterial endosymbiont with its archaeal host was accompanied by a massive endosymbiotic gene transfer resulting in a small mitochondrial genome which is just a ghost of the original incoming bacterial genome. This endosymbiotic gene transfer resulted in the loss of many genes, both from the bacterial symbiont as well the archaeal host. Loss of genes encoding redundant functions resulted in a replacement of the bulk of the host's metabolism for those originating from the endosymbiont. Glycolysis is one such metabolic pathway in which the original archaeal enzymes have been replaced by the bacterial enzymes from the endosymbiont. Glycolysis is a major catabolic pathway that provides cellular energy from the breakdown of glucose. The glycolytic pathway of eukaryotes appears to be bacterial in origin, and in well-studied model eukaryotes it takes place in the cytosol. In contrast, here we demonstrate that the latter stages of glycolysis take place in the mitochondria of stramenopiles, a diverse and ecologically important lineage of eukaryotes. Although our work is based on a limited sample of stramenopiles, it leaves open the possibility that the mitochondrial targeting of glycolytic enzymes in stramenopiles might represent the ancestral state for eukaryotes.TAW is supported by a Royal Society University Research Fellowship and
NERC grant NE/P00251X/1. Work in the lab of MvdG was supported by Wellcome Trust grant
078566/A/05/Z. PGK wishes to acknowledge support by the German Research Foundation (DFG, grant
KR 1661/6-1) and the Gordon and Betty Moore Foundation GBMF 4966 (grant DiaEdit)
NMR investigations of the interaction between the azo-dye sunset yellow and Fluorophenol
The interaction of small molecules with larger noncovalent assemblies is important across a wide range of disciplines. Here, we apply two complementary NMR spectroscopic methods to investigate the interaction of various fluorophenol isomers with sunset yellow. This latter molecule is known to form noncovalent aggregates in isotropic solution, and form liquid crystals at high concentrations. We utilize the unique fluorine-19 nucleus of the fluorophenol as a reporter of the interactions via changes in both the observed chemical shift and diffusion coefficients. The data are interpreted in terms of the indefinite self-association model and simple modifications for the incorporation of a second species into an assembly. A change in association mode is tentatively assigned whereby the fluorophenol binds end-on with the sunset yellow aggregates at low concentration and inserts into the stacks at higher concentrations
Inter-Observer Agreement on Subjects' Race and Race-Informative Characteristics
Health and socioeconomic disparities tend to be experienced along racial and ethnic lines, but investigators are not sure how individuals are assigned to groups, or how consistent this process is. To address these issues, 1,919 orthodontic patient records were examined by at least two observers who estimated each individual's race and the characteristics that influenced each estimate. Agreement regarding race is high for African and European Americans, but not as high for Asian, Hispanic, and Native Americans. The indicator observers most often agreed upon as important in estimating group membership is name, especially for Asian and Hispanic Americans. The observers, who were almost all European American, most often agreed that skin color is an important indicator of race only when they also agreed the subject was European American. This suggests that in a diverse community, light skin color is associated with a particular group, while a range of darker shades can be associated with members of any other group. This research supports comparable studies showing that race estimations in medical records are likely reliable for African and European Americans, but are less so for other groups. Further, these results show that skin color is not consistently the primary indicator of an individual's race, but that other characteristics such as facial features add significant information
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