253 research outputs found
The effect of Ca2+-mobilising hormones on the Na+-K+ pump in isolated rat liver hepatocytes (1982) FEBS Letters 141,49-52.
Robust zero-energy modes in an electronic higher-order topological insulator: the dimerized Kagome lattice
Quantum simulators are an essential tool for understanding complex quantum
materials. Platforms based on ultracold atoms in optical lattices and photonic
devices led the field so far, but electronic quantum simulators are proving to
be equally relevant. Simulating topological states of matter is one of the holy
grails in the field. Here, we experimentally realize a higher-order electronic
topological insulator (HOTI). Specifically, we create a dimerized Kagome
lattice by manipulating carbon-monoxide (CO) molecules on a Cu(111) surface
using a scanning tunneling microscope (STM). We engineer alternating weak and
strong bonds to show that a topological state emerges at the corner of the
non-trivial configuration, while it is absent in the trivial one. Contrarily to
conventional topological insulators (TIs), the topological state has two
dimensions less than the bulk, denoting a HOTI. The corner mode is protected by
a generalized chiral symmetry, which leads to a particular robustness against
perturbations. Our versatile approach to quantum simulation with artificial
lattices holds promises of revealing unexpected quantum phases of matter
Are Orai1 and Orai3 channels more important than calcium influx for cell proliferation?
AbstractTransformed and tumoral cells share the characteristic of being able to proliferate even when external calcium concentration is very low. We have investigated whether Human Embryonic Kidney 293 cells, human hepatoma cell Huh-7 and HeLa cells were able to proliferate when kept 72h in complete culture medium without external calcium. Our data showed that cell proliferation rate was similar over a range of external calcium concentration (2ÎĽM to 1.8mM). Incubation in the absence of external calcium for 72h had no significant effect on endoplasmic reticulum (ER) Ca2+ contents but resulted in a significant decrease in cytosolic free calcium concentration in all 3 cell types. Cell proliferation rates were dependent on Orai1 and Orai3 expression levels in HEK293 and HeLa cells. Silencing Orai1 or Orai3 resulted in a 50% reduction in cell proliferation rate. Flow cytometry analysis showed that Orai3 induced a small but significant increase in cell number in G2/M phase. RO-3306, a cdk-1 inhibitor, induced a 90% arrest in G2/M reversible in less than 15min. Our data showed that progression through G2/M phase after release from RO-3306-induced cell cycle arrest was slower in both Orai1 and Orai3 knock-downs. Overexpressing Orai1, Orai3 and the dominant negative non-permeant mutants E106Q-Orai1 and E81Q-Orai3 induced a 50% increase in cell proliferation rate in HEK293 cells. Our data clearly demonstrated that Orai1 and Orai3 proteins are more important than calcium influx to control cell proliferation in some cell lines and that this process is probably independent of ICRAC and Iarc
3′:5′-cyclic guanosine monophosphate (cGMP) potentiates the inositol 1,4,5-trisphosphate-evoked Ca2+ release in guinea-pig hepatocytes
Effect of the α-agonist noradrenaline on total and 45Ca2+ movements in mitochondria of rat liver cells
Oscillations of cytosolic free calcium concentration in the presence of intracellular antibodies to phosphatidylinositol 4,5-bisphosphate in voltage-clamped guinea-pig hepatocytes
Band offsets at zincblende-wurtzite GaAs nanowire sidewall surfaces
The band structure and the Fermi level pinning at clean and well-ordered sidewall surfaces of zincblende (ZB)-wurtzite (WZ) GaAs nanowires are investigated by scanning tunneling spectroscopy and density functional theory calculations. The WZ-ZB phase transition in GaAs nanowires introduces p-i junctions at the sidewall surfaces. This is caused by the presence of numerous steps, which induce a Fermi level pinning at different energies on the non-polar WZ and ZB sidewall facets.This study was financially supported by the
EQUIPEX program Excelsior, the European Community’s
Seventh Framework Program (Grant No. PITN-GA-2012-
316751, “Nanoembrace” Project) and the Impuls- und
Vernetzungsfonds of the Helmholtz-Gemeinschaft Deutscher
Forschungszentren under Grant No. HIRG-0014. T. Xu
acknowledges the support from the National Natural Science
Foundation of China (Grant No. 61204014)
Bottom-up strategies for the assembling of magnetic systems using nanoclusters
International audienceIn the frame of the 20th Anniversary of the Journal of Nanoparticle Research (JNR), our aim is to start from the historical context twenty, years ago and to give some recent results and perspectives concerning nanomagnets prepared from clusters preformed in the gas phase using the Low Energy Cluster Beam Deposition (LECBD) technique. In this paper, we focus our attention on the typical case of Co clusters embedded in various matrices to study interface magnetic anisotropy and magnetic interactions as a function of volume concentrations, and on still current and perspectives through two examples of binary metallic 3d-5d TM (namely CoPt and FeAu) clusters assemblies to illustrate size-related and nanoalloy phenomena on magnetic properties in well-defined mass-selected clusters. The structural and magnetic properties of these cluster assemblies were investigated using various experimental techniques that include High Resolution Transmission Electron Microscopy (HRTEM), Superconducting Quantum Interference Device (SQUID) magnetometry, as well as synchrotron techniques such as Extended X-Ray Absorption Fine Structure (EXAFS) and X-Ray Magnetic Circular Dichroism (XMCD). Depending on the chemical nature of both NPs and matrix, we observe different magnetic responses compared to their bulk counterparts. In particular, we show how finite size effects (size reduction) enhance their magnetic moment and how specific relaxation in nanoalloys can impact their magnetic anisotropy
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