Sharpness of the Berezinskii-Kosterlitz-Thouless Transition in Disordered NbN Films.

We present a comprehensive investigation of the Berezinskii-Kosterlitz-Thouless transition in ultrathin strongly disordered NbN films. Measurements of resistance, current-voltage characteristics, and kinetic inductance on the very same device reveal a consistent picture of a sharp unbinding transition of vortex-antivortex pairs that fit standard renormalization group theory without extra assumptions in terms of inhomogeneity. Our experiments demonstrate that the previously observed broadening of the transition is not an intrinsic feature of strongly disordered superconductors and provide a clean starting point for the study of dynamical effects at the Berezinskii-Kosterlitz-Thouless transition.

Quantized current steps due to the a.c. coherent quantum phase-slip effect.

The a.c. Josephson effect predicted in 1962 and observed experimentally in 1963 as quantized 'voltage steps' (the Shapiro steps) from photon-assisted tunnelling of Cooper pairs is among the most fundamental phenomena of quantum mechanics and is vital for metrological quantum voltage standards.

A wideband cryogenic microwave low-noise amplifier.

A broadband low-noise four-stage high-electron-mobility transistor amplifier was designed and characterized in a cryogen-free dilution refrigerator at the 3.8 K temperature stage. The obtained power dissipation of the amplifier is below 20 mW.

[Implant-prosthetic rehabilitation of a patient with an extensive maxillofacial defect].

The paper presents a clinical case demonstrating the necessity for scarce dental implants surgery in tissues affected by multiply surgical and radiological procedures. The patient underwent 13 interventions, 4 reconstructive procedures and 3 courses of radiotherapy resulting in extensive facial defect. An orthopedic construction was fixed in a defect on mechanically stable single-stage implants with screw-retained orthopedic platform and trans-zygomatic implants on the contralateral side.