Herein, we report the first [4+1] cyclization-aromatization reaction of acylsilanes and ɑ, β-unsaturated ketones. The unprecedented visible-light-induced reaction proceeded through mild conditions ... Description

We employ polarization-resolved Raman spectroscopy to study the multiband stoichiometric $T_c=35$ K superconductor ${\mathrm{CaKFe}}_4{\mathrm{As}}_4$. We do not detect Pomeranchuk-like electronic nematic fluctuations which were universally observed in the $XY\left(B_{2g}\right)$ symmetry Raman response for most families of the Fe-based superconductors. In the superconducting state we observe, consistent with a nodeless order parameter, a full spectral weight suppression at low energies and the emergence of a composite pair-breaking coherence feature at energies between 12 and 20 meV. We analyze the superconductivity-induced phonon self-energy effects and give an estimation for the electron-phonon coupling constant ${\lambda }^{\mathrm{\Gamma }}=0.0015$ which is insufficient to provide attraction for high-$T_c$ pairing.

A novel fluorescence sensor of NR-β-CD@AuNPs was prepared for the trace detection of nitrite in quantities as low as 4.25 × 10⁻³ μg∙mL⁻¹ in an aqueous medium. The fluorescence was due to the host-guest inclusion complexes between neutral red (NR) molecules and gold nanoparticles (AuNPs), which were modified by per-6-mercapto-beta-cyclodextrins (SH-β-CDs) as both a reducing agent and a stabilizer under microwave radiation. The color of the NR-β-CD@AuNPs changed in the presence of nitrite ions. A sensor was applied to the determination of trace nitrites in environmental water samples with satisfactory results.

Significance: The family of iron selenide (FeSe) superconductors is of great interest because it harbors an unusual nonmagnetic nematic state, exhibits a peculiar orbital-selective Cooper pairing, and has a strong potential for high-temperature superconductivity. Here, for F e S e 1 − x S x nonmagnetic metal, we report discovery of a pseudogap in the spectra of electronic long-wavelength charge quadrupole excitation below the nematic phase transition with temperature dependence of the gap’s magnitude reminiscent of a nematic order parameter. We argue that the intense continuum of excitations in the high-temperature phase with tetragonal symmetry arises due to non-Fermi liquid dynamics governed by Pomeranchuk fluctuations and that these fluctuations are suppressed in the symmetry-broken orthorhombic low-temperature phase, enabling the recovery of Fermi liquid properties.