This study examines the frequency and temperature dependence of conductivity, phase shift angle and capacity of the (FeCoZr)x (CaF2)(100−x) nanocomposites, with the metal phase content in the range ...of 45 at.% < x < 90 at.%, produced by pure argon ion-beam sputtering. It was found that for the metallic phase content lower than 67 at.% there are temperature dependencies of the dielectric type of conductivity, for which the derivative dσ/dT > 0. Activation energy of conductivity, determined from the Arrhenius plot, is about ΔE ≈ 0.061 eV. For a metallic phase content above 67 at.%, the metallic type of conductivity occurs, for which the derivative dσ/dT < 0. At the frequency of 100 Hz and at liquid nitrogen temperature (LNT) a dependence of conductivity on the content of the metallic phase was shown. In the area of low metallic phase content a rapid increase of conductivity occurs (over six orders of magnitude) and temperature dependence exhibits the dielectric type of conduction. For higher contents of the metallic phase the metallic type of conductivity occurs, which decreases with increasing temperature. Based on the analysis of conductivity depending on the content of the metallic phase, the percolation threshold was determined for the (FeCoZr)x (CaF2)(100−x) nanocomposite, the value of which is xc ≈ (65.8 ± 2) at.%. It was agreed that in nanocomposites below the percolation threshold there are resonance phenomena of currents and voltages similar to the resonance phenomena in RLC circuits containing conventional inductance coils and capacitors.
•Percolation threshold for (FeCoZr)x (CaF2)(100−x) produced by argon ion-beam sputtering.•Frequency and temperature dependence of conductivity, phase shift angle and capacity.•Activation energy of conductivity is about ΔE ≈ 0.061 eV.•Phenomena of current and voltage resonance similar to resonance phenomena of RLC circuits.
Heavy‐atom tunneling limits the lifetime and observability of bicyclo4.1.0hepta‐2,4,6‐triene, a key intermediate in the rearrangement of phenylcarbene. Bicyclo4.1.0hepta‐2,4,6‐triene had been ...proposed as the primary intermediate of the rearrangement of phenylcarbene, but despite many efforts evaded its characterization even in cryogenic matrices. By introducing fluorine substituents into the ortho‐positions of the phenyl ring of phenylcarbene, the highly strained cyclopropene 1,5‐difluorobicyclo4.1.0hepta‐2,4,6‐triene becomes stable enough to be characterized in argon matrices. However, even at 3 K this cyclopropene is only metastable and rearranges via heavy‐atom tunneling to the corresponding cycloheptatetraene. Calculations suggest that fluorination is necessary to slow down the tunneling rearrangement of the bicycloheptatriene. The parent bicycloheptatriene rapidly rearranges via heavy‐atom tunneling and therefore cannot be detected under matrix isolation conditions.
Mass-separated 187Ta114 in a high-spin isomeric state has been produced for the first time by multinucleon transfer reactions, employing an argon gas-stopping cell and laser ionization. Internal γ ...rays revealed a T1/2 = 7.3 ± 0.9 s isomer at 1778 ± 1 keV , which decays through a rotational band with perturbations associated with the approach to a prolate-oblate shape transition. Model calculations show less influence from triaxiality compared to heavier elements in the same mass region. The isomer-decay reduced E 2 hindrance factor fν = 27 ± 1 supports the interpretation that axial symmetry is approximately conserved.
The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-β (0νββ) decay of ^{76}Ge, whose discovery would have far-reaching implications in ...cosmology and particle physics. By operating bare germanium diodes, enriched in ^{76}Ge, in an active liquid argon shield, GERDA achieved an unprecedently low background index of 5.2×10^{-4} counts/(keV kg yr) in the signal region and met the design goal to collect an exposure of 100 kg yr in a background-free regime. When combined with the result of Phase I, no signal is observed after 127.2 kg yr of total exposure. A limit on the half-life of 0νββ decay in ^{76}Ge is set at T_{1/2}>1.8×10^{26} yr at 90% C.L., which coincides with the sensitivity assuming no signal.
ABSTRACT
Neuroinflammation plays a vital role in cerebral ischemic stroke (IS). In the acute phase of IS, microglia are activated toward the pro-inflammatory (M1) and anti-inflammatory (M2) ...phenotypes. Argon, an inert gas, can reduce neuroinflammation and alleviate ischemia/reperfusion (I/R) injury. However, whether argon regulates M1/M2 polarization to protect against I/R injury as well as the underlying mechanism has not been reported. In this study, we analyzed the activation and polarization of microglia after I/R injury with or without argon administration and explored the effects of argon on NLRP3 inflammasome-mediated inflammation in microglia in vitro and in vivo. The results showed that argon application inhibited the activation of M1 microglia/macrophage in the ischemic penumbra and the expression of proteins related to NLRP3 inflammasome and pyroptosis in microglia. Argon administration also inhibited the expression and processing of IL-1β, a primary pro-inflammatory cytokine. Thus, argon alleviates I/R injury by inhibiting pro-inflammatory reactions via suppressing microglial polarization toward M1 phenotype and inhibiting the NF-κB/NLRP3 inflammasome signaling pathway. More importantly, we showed that argon worked better than the specific NLRP3 inflammasome inhibitor MCC950 in suppressing neuroinflammation and protecting against cerebral I/R injury, suggesting the therapeutic potential of argon in neuroinflammation-related neurodegeneration diseases as a potent gas inhibitor of the NLRP3 inflammasome signaling pathway.
g Factor of Boronlike Argon Ar4013 Arapoglou, I; Egl, A; Höcker, M ...
Physical review letters,
06/2019, Letnik:
122, Številka:
25
Journal Article
Recenzirano
We have measured the ground-state g factor of boronlike argon Ar4013+ with a fractional uncertainty of 1.4×10−9 with a single ion in the newly developed Alphatrap double Penning-trap setup. The value ...of g=0.663 648 455 32(93) obtained here is in agreement with our theoretical prediction of 0.663 648 12(58). The latter is obtained accounting for quantum electrodynamics, electron correlation, and nuclear effects within the state-of-the-art theoretical methods. Our experimental result distinguishes between existing predictions that are in disagreement, and lays the foundations for an independent determination of the fine-structure constant.
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