Quantum Phase transition under pressure in a heavily hydrogen-doped iron-based superconductor LaFeAsO

Hydrogen (H)-doped LaFeAsO is a prototypical iron-based superconductor. However, its phase diagram extends beyond the standard framework, where a superconducting (SC) phase follows an antiferromagnetic (AF) phase upon carrier doping; instead, the SC phase is sandwiched between two AF phases appearing in lightly and heavily H-doped regimes. We performed nuclear magnetic resonance (NMR) measurements under pressure, focusing on the second AF phase in the heavily H-doped regime. The second AF phase is strongly suppressed when a pressure of 3.0 GPa is applied, and apparently shifts to a highly H-doped regime, thereby a "bare" quantum critical point (QCP) emerges. A quantum critical regime emerges in a paramagnetic state near the QCP, however, the influence of the AF critical fluctuations to the SC phase is limited in the narrow doping regime near the QCP. The optimal SC condition ($T_c \sim$ 48 K) is unaffected by AF fluctuations

Laparoscopic and Endoscopic Cooperative Surgery for Gastric Submucosal Tumor Near Esophagogastric Junction With Sliding Hiatal Hernia

The usefulness of laparoscopic and endoscopic cooperative surgery (LECS) for gastric submucosal tumors in the cardiac region has been reported in recent years. However, LECS for submucosal tumors at the esophagogastric junction with hiatal sliding esophageal hernia has not been reported, and its validity as a treatment method is unknown. The patient was a 51-year-old man with a growing submucosal tumor in the cardiac region. Surgical resection was indicated because a definitive diagnosis of the tumor was not determined. The lesion was a luminal protrusion tumor, located on the posterior wall of the stomach 20 mm from the esophagogastric junction, and had a maximum diameter of 16.3 mm on endoscopic ultrasound examination. Because of the hiatal hernia, the lesion could not be detected from the gastric side by endoscopy. Local resection was considered to be feasible because the resection line did not extend into the esophageal mucosa and the resection site could be less than half the circumference of the lumen. The submucosal tumor was resected completely and safely by LECS. The tumor was diagnosed as a gastric smooth muscle tumor finally. Nine months after surgery, a follow-up endoscopy showed reflux esophagitis. LECS was a useful technique for submucosal tumors of the cardiac region with hiatal hernia, but fundoplication might be considered for preventing backflow of gastric acid

Elevation of Ammonia Contents in the Cerebral Hemisphere under the Blood-Brain Barrier Opening

Elevation of ammonia contents was observed 1 hr following infusion of 4% ammonium acetate only in the cerebral hemisphere where reversible opening of the blood-brain barrier was induced by intracarotid injection of 0.1% deoxycholic acid. This finding suggests that ammonia may contribute to hepatic encephalopathy, when the permeability of the blood-brain barrier is altered

Bile Acid and Ammonia-Induced Brain Edema in Rats

Infusion of bile acid such as chenodeoxycholic acid or deoxycholic acid through the carotid artery of rats produced reversible and unilateral opening of the blood-brain barrier without any tissue damage. Intravenous drip infusion of ammonium acetate during the opening resulted in severe edema of the brain. The results suggest the importance of bile acid and ammonia for the pathogenesis of brain edema frequently observed in acute hepatic failure

Pressure-induced quantum critical point in a heavily hydrogen-doped iron-based superconductor LaFeAsO

An iron-based superconductor LaFeAsO$_{1-x}$H$_x$ (0 $\leq x \leq$ 0.6) undergoes two antiferromagnetic (AF) phases upon H doping. We investigated the second AF phase ($x$=0.6) using NMR techniques under pressure. At pressures up to 2 GPa, the ground state is a spin-density-wave state with a large gap; however, the gap closes at 4.0 GPa, suggesting a pressure-induced quantum critical point. Interestingly, the gapped excitation coexists with gapless magnetic fluctuations at pressures between 2 and 4 GPa. This coexistence is attributable to the lift up of the $d_{xy}$ orbital to the Fermi level, a Lifshitz transition under pressure

The Intensity of Satellite Reflections in Electron Diffraction Patterns from Evaporated Alloy Films with CuAu II Type Superstructure

In order to elucidate the origin of satellite reflections flanking the direct spot in the electron diffraction pattern of a single crystal evaporated film with CuAu II type superlattice, the peak as well as integrated intensities have been measured as functions of the wavelength of electrons corresponding to the accelerating voltage from 75 to 280KV. It has been revealed that the intensity of the satellite in question relative to a fundamental reflection consists of two parts, a major part which depends on the wavelength in such a way as predicted by the theory of multiple reflection, and the other minor part which is independent of the wavelength. The existence of the latter part shows that the reflection is not a forbidden one and, therefore, a lattice modulation accompanies the regular anti-phase structure. Fourier potential due to this lattice modulation, V_s, is estimated to be in the order of one tenth the magnitude of V_ Some consideration concerning the nature of the modulation is given by comparing the results of electron and X-ray diffraction studies