513 research outputs found
Signatures of quantum criticality in hole-doped and chemically pressurized EuFe_2As_2 single crystals
We study the effect of hole-doping and chemical pressure (isovalent doping)
in single crystals of KEuFeAs and
EuFe(AsP), respectively, by measurements of the
thermopower, , and electrical resistivity, . The evolution of
upon doping indicates drastic changes of the electronic configuration at
critical values and , respectively,
as the spin-density-wave transition is completely suppressed and
superconductivity (SC) emerges. For the case of chemical pressure, the
comparison with published ARPES measurements indicates a Lifshitz transition at
. The temperature dependences and
observed in the normal state above the SC transition
suggest quantum criticality in both systems.Comment: PRB accepte
The Environment and Healthcare-Acquired Infections: Why Accurate Reporting and Evaluation of Biological Plausibility Are Important
Spectroscopic characterisation and thermodynamics of the complexation of Np(V) with sulfate up to 200 °C
Environmental occurrence of the Whipple's disease bacterium (Tropheryma whippelii).
Whipple's disease is a systemic disorder in which a gram-positive rod-shaped bacterium is constantly present in infected tissues. After numerous unsuccessful attempts to culture this bacterium, it was eventually characterized by 16S rRNA gene analysis to be a member of the actinomycetes. The name Tropheryma whippelii was proposed. Until now, the bacterium has only been found in infected human tissues, but there is no evidence for human-to-human transmission. Here we report the detection of DNA specific for the Whipple's disease bacterium in 25 of 38 wastewater samples from five different sewage treatment plants in the area of Heidelberg, Germany. These findings provide the first evidence that T. whippelii occurs in the environment, within a polymicrobial community. This is in accordance with the phylogenetic relationship of this bacterium as well as with known epidemiological aspects of Whipple's disease. Our data argue for an environmental source for infection with the Whipple's disease bacterium
The complexation of neptunium(V) with fluoride at elevated temperatures: Speciation and thermodynamics
Thermodynamics and Structure of Neptunium(V) Complexes with Formate. Spectroscopic and Theoretical Study
Diversity of Helicobacter pylori vacA and cagA genes and relationship to VacA and CagA protein expression, cytotoxin production, and associated diseases
Persistent detwinning of iron pnictides by small magnetic fields
Our comprehensive study on EuFeAs reveals a dramatic reduction of
magnetic detwinning fields compared to other AFeAs (A = Ba, Sr, Ca)
iron pnictides by indirect magneto-elastic coupling of the Eu ions. We
find that only 0.1T are sufficient for persistent detwinning below the local
Eu ordering; above = 19K, higher fields are necessary.
Even after the field is switched off, a significant imbalance of twin domains
remains constant up to the structural and electronic phase transition (190K).
This persistent detwinning provides the unique possibility to study the low
temperature electronic in-plane anisotropy of iron pnictides without applying
any symmetrybreaking external force.Comment: accepted by Physical Review Letter
Upper critical magnetic field in K0.83Fe1.83Se2 and Eu0.5K0.5Fe2As2 single crystals
The H-T phase diagrams of single crystalline electron-doped K0.83Fe1.83Se2
(KFS1), K0.8Fe2Se2 (KFS2) and hole-doped Eu0.5K0.5Fe2As2 (EKFA) have been
deduced from tunnel diode oscillator-based contactless measurements in pulsed
magnetic fields up to 57 T for the inter-plane (H//c) and in-plane (H//ab)
directions. The temperature dependence of the upper critical magnetic field
Hc2(T) relevant to EFKA is accounted for by the Pauli model including an
anisotropic Pauli paramagnetic contribution (\mu_BHp=114 T for H//ab and 86 T
for H//c). This is also the case of KFS1 and KFS2 for H//ab whereas a
significant upward curvature, accounted for by a two-gap model, is observed for
H//c. Despite the presence of antiferromagnetic lattice order within the
superconducting state of the studied compounds, no influence of magnetic
ordering on the temperature dependence of Hc2(T) is observed.Comment: 9 pages, 5 figures. arXiv admin note: text overlap with
arXiv:1104.561
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