Doping-dependent superconducting physical quantities of K-doped BaFe[Formula: see text]As[Formula: see text] obtained through infrared spectroscopy.

We investigated four single crystals of K-doped BaFe[Formula: see text]As[Formula: see text] (Ba-122), Ba[Formula: see text]K[Formula: see text]Fe[Formula: see text]As[Formula: see text] with [Formula: see text] 0.29, 0.36, 0.40, and 0.51, using infrared spectroscopy. We explored a wide variety of doping levels, from under- to overdoped. We obtained the superfluid plasma frequencies ([Formula: see text]) and corresponding London penetration depths ([Formula: see text]) from the measured optical conductivity spectra. We also extracted the electron-boson spectral density (EBSD) functions using a two-parallel charge transport channel approach in the superconducting (SC) state. From the extracted EBSD functions, the maximum SC transition temperatures ([Formula: see text]) were determined using a generalized McMillan formula and the SC coherence lengths ([Formula: see text]) were calculated using the timescales encoded in the EBSD functions and reported Fermi velocities. We identified some similarities and differences in the doping-dependent SC quantities between the K-doped Ba-122 and the hole-doped cuprates. We expect that the various SC quantities obtained across the wide doping range will provide helpful information for establishing the microscopic pairing mechanism in Fe-pnictide superconductors.

Temperature-dependent optical properties of self-doped superconducting Fe-pnictide, Sr2VO3FeAs.

We performed an infrared spectroscopic study on a single crystal of Sr2VO3FeAs grown by a self-flux method. This layered material system consists of two alternative layers of [SrVO3]-1 and [SrFeAs]+1. Since the typical size of single crystalline Sr2VO3FeAs samples is 200 [Formula: see text] 200 [Formula: see text] 10 [Formula: see text]m3 an optical study on this material is challenging. We observed an additional interband transition around 1000 cm-1, which is absent in other doped Ba-122 Fe-pnictides. The origin of this additional transition is not clearly known yet. We also observed a hidden Fermi liquid behavior. Interestingly, we observed a Fano line-shaped phonon which appears near 555 cm-1 below 200 K and shows a strong blue-shift when the temperature is lowered. The amplitude, width, and asymmetric Fano parameter of this phonon show anomalies at 150 K, which are probably related to an electronic phase observed below 155 K recently by an NMR study (Ok et al 2017 Nat. Commun. 8 2167). Our finding may help to understand the electronic phase observed previously in the same material.

Physician liability for procedure related injury: Focused on central venous catheterization.

Central venous catheterization (CVC) is one of essential procedures in critical care medicine. CVC is relatively safe when performed by experienced physicians. Complications may occur due to various risk factors. Although the incidence of CVC-related complications is not high, a serious risk may ensue in cases of such complications. Procedure related complications could lead to civil and criminal lawsuits. This study reviewed the occurrence patterns and rulings of the courts related to CVC in South Korea and tried to find pitfalls that medical professionals should keep in mind before, during and after medical procedures. Various patterns of CVC-related lawsuits have been raised. During the procedure, physicians should perform their duty considering risk factors such as patients' underlying diseases and age. In addition, before the procedure, physicians must obtain written consent for CVC from patients or their legal guardians including explanation of rare complications that could be lethal. After the completion of CVC, surveillance of anticipated complications including chest radiographs should be conducted for the immediate management of any possible complications.

Hidden non-Fermi liquid behavior caused by magnetic phase transition in Ni-doped Ba-122 pnictides.

We studied two BaFe(2-x)N(I)xAs2 (Ni-doped Ba-122) single crystals at two different doping levels (underdoped and optimally doped) using an optical spectroscopic technique. The underdoped sample shows a magnetic phase transition around 80 K. We analyze the data with a Drude-Lorentz model with two Drude components (D1 and D2). It is known that the narrow D1 component originates from electron carriers in the electron-pockets and the broad D2 mode is from hole carriers in the hole-pockets. While the plasma frequencies of both Drude components and the static scattering rate of the broad D2 component show negligible temperature dependencies, the static scattering rate of the D1 mode shows strong temperature dependence for the both samples. We observed a hidden quasi-linear temperature dependence in the scattering rate of the D1 mode above and below the magnetic transition temperature while in the optimally doped sample the scattering rate shows a more quadratic temperature dependence. The hidden non-Fermi liquid behavior in the underdoped sample seems to be related to the magnetic phase of the material.