Indium selenide: An insight into electronic band structure and surface excitations

We have investigated the electronic response of single crystals of indium selenide by means of angle-resolved photoemission spectroscopy, electron energy loss spectroscopy and density functional theory. The loss spectrum of indium selenide shows the direct free exciton at similar to 1.3 eV and several other peaks, which do not exhibit dispersion with the momentum. The joint analysis of the experimental band structure and the density of states indicates that spectral features in the loss function are strictly related to single-particle transitions. These excitations cannot be considered as fully coherent plasmons and they are damped even in the optical limit, i.e. for small momenta. The comparison of the calculated symmetry-projected density of states with electron energy loss spectra enables the assignment of the spectral features to transitions between specific electronic states. Furthermore, the effects of ambient gases on the band structure and on the loss function have been probed

IGRA test for TB in COVID-19: role of corticosteroids

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The Synthesis of [{n-Bu2Sn(S2N2)}2] and its use in the preparation of Organometallic Iridium Sulfur Nitrogen Complexes

The addition of [n-Bu2SnCl2] to a solution of [S4N3][Cl] in liquid ammonia gave after extraction of the dry reaction mixture the new tin disulfur dinitrido compound [{n-Bu2Sn(S2N2)}(2)] (1). Reaction of [{n-Bu2Sn(S2N2)}(2)] (1) with the pentamethylcyclopentadienyl (Cp*) iridium derivatives [{IrCl(mu-Cl)(eta(5)-C5Me5)}(2)] or [(eta(5)-C5Me5)IrCl2(PPh3)] gave different products, which were dependent on the reactant ratios. A 1:1 reaction between 1 and [{IrCl(mu-Cl)(eta(5)-C5Me5)}(2)] gave only [(eta(5)-C5Me5)Ir(S2N2)] (2) in moderate yield; the same product in higher yield was obtained from a 2:1 reaction between 1 and [(eta(5)-C5Me5)IrCl2(PPh3)]. Reaction of 1 and [(eta(5)-C5Me5)(2)IrCl2(PPh3)] (1:1 molar ratio) in the presence of NH4[PF6] gave the unusual bimetallic species [(eta(5)-C5Me5)IrCl(PPh3)(S2N2)Ir(eta(5)-C5Me5)][PF6] (3). The X-ray crystal structures of 1, 2, and 3 are reported.PostprintPeer reviewe

Ventilatory associated barotrauma in COVID-19 patients: A multicenter observational case control study (COVI-MIX-study)

Background: The risk of barotrauma associated with different types of ventilatory support is unclear in COVID-19 patients. The primary aim of this study was to evaluate the effect of the different respiratory support strategies on barotrauma occurrence; we also sought to determine the frequency of barotrauma and the clinical characteristics of the patients who experienced this complication. Methods: This multicentre retrospective case-control study from 1 March 2020 to 28 February 2021 included COVID-19 patients who experienced barotrauma during hospital stay. They were matched with controls in a 1:1 ratio for the same admission period in the same ward of treatment. Univariable and multivariable logistic regression (OR) were performed to explore which factors were associated with barotrauma and in-hospital death. Results: We included 200 cases and 200 controls. Invasive mechanical ventilation was used in 39.3% of patients in the barotrauma group, and in 20.1% of controls (p<0.001). Receiving non-invasive ventilation (C-PAP/PSV) instead of conventional oxygen therapy (COT) increased the risk of barotrauma (OR 5.04, 95% CI 2.30 - 11.08, p<0.001), similarly for invasive mechanical ventilation (OR 6.24, 95% CI 2.86-13.60, p<0.001). High Flow Nasal Oxygen (HFNO), compared with COT, did not significantly increase the risk of barotrauma. Barotrauma frequency occurred in 1.00% [95% CI 0.88-1.16] of patients; these were older (p=0.022) and more frequently immunosuppressed (p=0.013). Barotrauma was shown to be an independent risk for death (OR 5.32, 95% CI 2.82-10.03, p<0.001). Conclusions: C-PAP/PSV compared with COT or HFNO increased the risk of barotrauma; otherwise HFNO did not. Barotrauma was recorded in 1.00% of patients, affecting mainly patients with more severe COVID-19 disease. Barotrauma was independently associated with mortality. Trial registration: this case-control study was prospectively registered in clinicaltrial.gov as NCT04897152 (on 21 May 2021)

Transition-metal Isocyanide Bonding - A Photoelectron Spectroscopic Study of Iron Tetracarbonyl Isocyanide Complexes

The He I and X-ray photoelectron spectra of the iron tetracarbonyl complexes of methyl, tert-butyl, trimethylsilyl, and phenyl isocyanide have been obtained. The bonding properties of these isocyanides are compared with those of carbon monoxide by using the core-binding energy data to interpret the valence ionization energies. The data show that all the isocyanides have comparable a-donor ability and that, in the Fe(C0I4CNR complexes, they are significantly weaker u donors than carbon monoxide. The stronger u-donor character of the coordinated CO ligands is presumably due to the u-a synergism of the Fe-CO bonding. The net interaction of an isocyanide ligand with the iron d orbitals leaves the energy of the d orbitals destabilized relative to Fe(C0)5. The data indicate that the relative energies of interaction of the d orbitals with the filled ligand a orbitals and the empty ligand a* orbitals are different in Fe-CO and Fe-CNR bonds, with the interactions of the filled ligand a orbitals being relatively more important in Fe-CNR bonds than in Fe-CO bonds. The net electron withdrawal by a coordinated isocyanide ligand, although significant, is much lower than that by a coordinated carbonyl ligand. It is clear that the interactions of transition metals with isocyanides (and probably also with other ligands with similar electronic structures) cannot be adequately described without considering the combined a-donor, a-acceptor, and a-donor characters of the ligands

Scanning tunneling microscopy and spectroscopy of Mo clusters grown on TiO2(110).

International audienceMolybdenum was deposited in two steps (3 eq. ML and 1 eq. ML) on the light blue rutile TiO2(110) (1 · 1) surface at room temperature, each Mo deposition cycle being followed by an annealing up to 950–1000 K. This procedure was found to lead to formation of separated clusters having a size in very wide range (1–20 nm). Scanning tunneling microscopy showed a dependence of the cluster morphology as a function of the size. The scanning tunneling spectra of Mo clusters was studied as a function of cluster dimensions and discussed in comparison with photoelectron spectroscopy results previously obtained for homogeneous Mo films. The dI/dV curves do not display the valence band structure of deposited material, which could be explained by the Schottky barrier formation