71 research outputs found
Ultrasound Investigations of Orbital Quadrupolar Ordering in UPd_3
For a high-quality single crystal of UPd_3 we present the relevant elastic
constants and ultrasonic attenuation data. In addition to the magnetic phase
transition at T_2=4.4 +/- 0.1K and the quadrupolar transition at T_1~6.8K, we
find orbital ordering at T_0=7.6 +/- 0.1K concomitant with a symmetry change
from hexagonal to orthorhombic. A striking feature is the splitting of the
phase transition at T_1 into a second-order transition at T_{+1}=6.9 +/- 0.05K
and a first-order transition at T_{-1}=6.7 +/- 0.05K. For the four phase
transitions, the quadrupolar order parameters and the respective symmetry
changes are specified.Comment: 14 pages (RevTex), 3 eps-figures, accepted by PR
UV luminescence in Gd-doped silica and phosphosilicate optical fibers
Gd-doped silica and phosphosilicate fibers were pulled from preforms fabricated using the rod-in-tube technique and the solution doping technique, respectively. Ultraviolet (UV)-B luminescence from trivalent Gd at around 312 nm given by transition from first excited state to ground state were observed under deep UV excitations
Magnetic Field Effects on Neutron Diffraction in the Antiferromagnetic Phase of
We discuss possible magnetic structures in UPt based on our analysis of
elastic neutron-scattering experiments in high magnetic fields at temperatures
. The existing experimental data can be explained by a single-{\bf q}
antiferromagnetic structure with three independent domains. For modest in-plane
spin-orbit interactions, the Zeeman coupling between the antiferromagnetic
order parameter and the magnetic field induces a rotation of the magnetic
moments, but not an adjustment of the propagation vector of the magnetic order.
A triple-{\bf q} magnetic structure is also consistent with neutron
experiments, but in general leads to a non-uniform magnetization in the
crystal. New experiments could decide between these structures.Comment: 5 figures included in the tex
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Reliable identification of protein-protein interactions by crosslinking mass spectrometry
Protein-protein interactions govern most cellular pathways and processes, and multiple technologies have emerged to systematically map them. Assessing the error of interaction networks has been a challenge. Crosslinking mass spectrometry is currently widening its scope from structural analyses of purified multi-protein complexes towards systems-wide analyses of protein-protein interactions (PPIs). Using a carefully controlled large-scale analysis of Escherichia coli cell lysate, we demonstrate that false-discovery rates (FDR) for PPIs identified by crosslinking mass spectrometry can be reliably estimated. We present an interaction network comprising 590 PPIs at 1% decoy-based PPI-FDR. The structural information included in this network localises the binding site of the hitherto uncharacterised protein YacL to near the DNA exit tunnel on the RNA polymerase.TU Berlin, Open-Access-Mittel – 2021DFG, 390540038, EXC 2008: Unifying Systems in Catalysis "UniSysCat"DFG, 392923329, GRK 2473: Bioaktive Peptide - Innovative Aspekte zur Synthese und BiosyntheseDFG, 426290502, Erfassung der strukturellen Organisation des Mycoplasma pneumoniae Proteoms mittels in-Zell Crosslinking-Massenspektrometri
An assessment of the vertical diffusive flux of iron and other nutrients to the surface waters of the subpolar North Atlantic Ocean
In this study we report diapycnal diffusive fluxes of dissolved iron (dFe), dissolved aluminium (dAl) and the major macronutrients to the surface waters of the North Atlantic subpolar gyre. Turbulent diffusivities at the base of the summer mixed layer ranged from 0.01 to 0.5 (median 0.07) cm2 s−1 and daily macronutrient fluxes into the surface mixed layer typically represented < 0.5% of integrated mixed layer inventories, although fluxes were highly variable. Elevated nutrient fluxes of up to 4% of mixed layer inventories were identified on the Greenland Shelf, where integrated nutrient pools were lowest due to localised shoaling of the mixed layer. Diffusive fluxes of dFe and dAl were typically <0.1% of mixed layer inventories but were also highly variable between stations. Approximations of daily phytoplankton nutrient and Fe uptake indicate that the diffusive flux may at best represent <10% of phytoplankton macronutrient uptake, and only 1% of daily phytoplankton Fe uptake. The daily turbulent diffusive flux of dFe was comparable in magnitude to coincident estimates of aeolian Fe supply but despite shallower than normal convective mixing in winter 2010 the diffusive supply was 22 and 59 times smaller than the annual convective supply of Fe to the Irminger and Iceland basins respectively. The general picture obtained from this study is one of small magnitude diffusive nutrient and Fe fluxes to the subpolar North Atlantic during the period of annual nutrient minima and indicates that the diffusive supply mechanism is unlikely to alleviate the recently identified presence of seasonal iron limitation within the North Atlantic subpolar gyre; a condition exacerbated by low dFe:NO3− ratios in subsurface source waters
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