927 research outputs found
Геохимия твердой фазы снежного покрова в окрестностях цементного завода (на примере г. Топки Кемеровской области)
Dress A, RUCH E, TRIESCH E. Extremals of the cone of norms and the cohomology of c3-stratifications. Advances in Applied Mathematics. 1992;13(1):1-47
Microcoil High-Resolution Magic Angle Spinning NMR Spectroscopy
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A novel physiological role for ARF1 in the formation of bidirectional tubules from the Golgi.
Capitalizing on CRISPR/Cas9 gene-editing techniques and super-resolution nanoscopy, we explore the role of the small GTPase ARF1 in mediating transport steps at the Golgi. Besides its well-established role in generating COPI vesicles, we find that ARF1 is also involved in the formation of long (∼3 µm), thin (∼110 nm diameter) tubular carriers. The anterograde and retrograde tubular carriers are both largely free of the classical Golgi coat proteins coatomer (COPI) and clathrin. Instead, they contain ARF1 along their entire length at a density estimated to be in the range of close packing. Experiments using a mutant form of ARF1 affecting GTP hydrolysis suggest that ARF1[GTP] is functionally required for the tubules to form. Dynamic confocal and stimulated emission depletion imaging shows that ARF1-rich tubular compartments fall into two distinct classes containing 1) anterograde cargoes and clathrin clusters or 2) retrograde cargoes and coatomer clusters
Spectroscopic perspective on the interplay between electronic and magnetic properties of magnetically doped topological insulators
We combine low energy muon spin rotation (LE-SR) and soft-X-ray
angle-resolved photoemission spectroscopy (SX-ARPES) to study the magnetic and
electronic properties of magnetically doped topological insulators,
(Bi,Sb)Te. We find that one achieves a full magnetic volume fraction in
samples of (V/Cr)(Bi,Sb)Te at doping levels x 0.16.
The observed magnetic transition is not sharp in temperature indicating a
gradual magnetic ordering. We find that the evolution of magnetic ordering is
consistent with formation of ferromagnetic islands which increase in number
and/or volume with decreasing temperature. Resonant ARPES at the V edge
reveals a nondispersing impurity band close to the Fermi level as well as V
weight integrated into the host band structure. Calculations within the
coherent potential approximation of the V contribution to the spectral function
confirm that this impurity band is caused by V in substitutional sites. The
implications of our results on the observation of the quantum anomalous Hall
effect at mK temperatures are discussed
BOOST -- A Satellite Mission to Test Lorentz Invariance Using High-Performance Optical Frequency References
BOOST (BOOst Symmetry Test) is a proposed satellite mission to search for
violations of Lorentz invariance by comparing two optical frequency references.
One is based on a long-term stable optical resonator and the other on a
hyperfine transition in molecular iodine. This mission will allow to determine
several parameters of the standard model extension in the electron sector up to
two orders of magnitude better than with the current best experiments. Here, we
will give an overview of the mission, the science case and the payload.Comment: 11 pages, 2 figures, accepted for publication in Phys. Rev.
Current density distribution in cylindrical Li-Ion cells during impedance measurements
In this work, modified commercial cylindrical lithium-ion cells with multiple separate current tabs are used to analyze the influence of tab pattern, frequency and temperature on electrochemical impedance spectroscopy. In a first step, the effect of different current tab arrangements on the impedance spectra is analyzed and possible electrochemical causes are discussed. In a second step, one terminal is used to apply a sinusoidal current while the other terminals are used to monitor the local potential distribution at different positions along the electrodes of the cell. It is observed that the characteristic decay of the voltage amplitude along the electrode changes non-linearly with frequency, where high-frequent currents experience a stronger attenuation along the current collector than low-frequent currents. In further experiments, the decay characteristic is controlled by the cell temperature, driven by the increasing resistance of the current collector and the enhanced kinetic and transport properties of the active material and electrolyte. Measurements indicate that the ac current distribution depends strongly on the frequency and the temperature. In this context, the challenges for electrochemical impedance spectroscopy as cell diagnostic technique for commercial cells are discussed
Communication: Dopant-induced solvation of alkalis in liquid helium nanodroplets
Alkali metal atoms and small alkali clusters are classic heliophobes and when
in contact with liquid helium they reside in a dimple on the surface. Here we
show that alkalis can be induced to submerge into liquid helium when a highly
polarizable co-solute, C60, is added to a helium nanodroplet. Evidence is
presented that shows that all sodium clusters, and probably single Na atoms,
enter the helium droplet in the presence of C60. Even clusters of cesium, an
extreme heliophobe, dissolve in liquid helium when C60 is added. The sole
exception is atomic Cs, which remains at the surface
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