Superconductivity of barium with highest transition temperatures in metallic materials at ambient pressure.

Pressure-induced superconductivity often occurs following structural transition under hydrostatic pressure (PHP) but disappears after the pressure is released. In the alkali-earth metal barium, superconductivity appears after structural transformation from body-centered cubic structure to hexagonal-close-packed (hcp) structure at PHP = 5 GPa, and the superconducting transition temperature (Tc) reaches a maximum of 5 K at PHP = 18 GPa. Furthermore, by stabilizing the low-temperature phase at PHP ~ 30 GPa, Tc reached a higher level of 8 K. Herein, we demonstrate a significantly higher Tc superconductivity in Ba even at ambient pressure. This was made possible through severe plastic deformation of high-pressure torsion (HPT). In this HPT-processed Ba, we observed superconductivity at Tc = 3 K and Tc = 24 K in the quasi-stabilized hcp and orthorhombic structures, respectively. In particular, the latter Tc represents the highest value achieved at ambient pressure among single-element superconducting metals, including intermetallics. The phenomenon is attributed to a strained high-pressure phase, stabilized by residual strains generated from lattice defects such as dislocations and grain boundaries. Significantly, the observed Tc far exceeds predictions from DFT calculations under normal hydrostatic compressions. The study demonstrates the importance of utilizing high-pressure strained phases as quasi-stable superconducting states at ambient pressure.

Analysis of distribution, collection, and confirmation of capacity dependency of small extracellular vesicles toward a therapy for liver cirrhosis.

BACKGROUND: The progression of liver fibrosis leads to portal hypertension and liver dysfunction. However, no antifibrotic agents have been approved for cirrhosis to date, making them an unmet medical need. Small extracellular vesicles (sEVs) of mesenchymal stem cells (MSCs) are among these candidate agents. In this study, we investigated the effects of sEVs of MSCs, analyzed their distribution in the liver post-administration, whether their effect was dose-dependent, and whether it was possible to collect a large number of sEVs. METHODS: sEVs expressing tdTomato were generated, and their uptake into constituent liver cells was observed in vitro, as well as their sites of uptake and cells in the liver using a mouse model of liver cirrhosis. The efficiency of sEV collection using tangential flow filtration (TFF) and changes in the therapeutic effects of sEVs in a volume-dependent manner were examined. RESULTS: The sEVs of MSCs accumulated mostly in macrophages in damaged areas of the liver. In addition, the therapeutic effect of sEVs was not necessarily dose-dependent, and it reached a plateau when the dosage exceeded a certain level. Furthermore, although ultracentrifugation was commonly used to collect sEVs for research purposes, we verified that TFF could be used for efficient sEV collection and that their effectiveness is not reduced. CONCLUSION: In this study, we identified some unknown aspects regarding the dynamics, collection, and capacity dependence of sEVs. Our results provide important fundamentals for the development of therapies using sEVs and hold potential implications for the therapeutic applications of sEV-based therapies for liver cirrhosis.

Two rare pancreatic parenchymal hemorrhagic lesions associated with acute pancreatitis in acute liver failure: a case report and literature review.

Acute pancreatitis is an uncommon occurrence in acute liver failure. Furthermore, such cases are rarely complicated by parenchymal hemorrhages. Herein, we report the case of a 69-year-old male patient with multiple pancreatic parenchymal hemorrhages concomitant with acute liver failure. The patient underwent conservative treatment for acute liver failure caused by hepatitis B virus infection. Plain computed tomography on the 30th day revealed two high-density mass lesions in the pancreatic body and tail, which were suspected to be multiple pancreatic parenchymal hemorrhages. Despite restarting gabexate mesylate, the patient died of multiple organ failure on the 49th day. The clinical information of the present case and our literature review of 61 similar cases in 43 case reports identified via a systematic keyword search of the PubMed database, which described acute pancreatitis concomitant with acute hepatitis and acute liver failure, will aid physicians in the diagnosis and treatment of this rare condition.

Methotrexate-associated proliferative disorder in the lower esophagus extending to the gastroesophageal junction: A case report.

A 64-year-old woman was receiving oral methotrexate (MTX) for rheumatoid arthritis (RA) for 15 years. She underwent esophagogastroduodenoscopy because of discomfort in the chest. Endoscopic findings revealed an ulcer in the lower esophagus extending to the gastroesophageal junction (EGJ). The ulcer occupied half of the esophageal lumen and had a sharp and clear margin. Magnifying narrow-band imaging endoscopy revealed the deposition of white plaque, and there were few microvessels in the edge and bottom of the ulcer. Histologic examination of the biopsy specimens from the oral edge of the lesion revealed proliferation of atypical lymphoid cells (immunophenotype results: CD20 [+], CD3 [partially +], CD5 [-], and BCL-2 [-]]. The patient was diagnosed with methotrexate-associated lymphoproliferative disorder (MTX-LPD) and was advised to stop MTX intake. After 2 months of stopping MTX, the ulcer was found to be almost regressed and showed signs of healing. MTX-LPD in the lower esophagus extending to the EGJ is extremely rare. This case can help in expanding the understanding of esophageal MTX-LPD.

Balloon-occluded retrograde transvenous obliteration for gastric varices improves hepatic functional reserve in long-term follow-up.

BACKGROUND AND AIM: Balloon-occluded retrograde transvenous obliteration (BRTO) has been widely adopted for the management of gastric fundal varices (GVs). There are a few reports that BRTO leads to the improvement of mid-term and long-term hepatic functional reserve (HFR). We retrospectively investigated the long-term effect on HFR and prognosis among patients who had undergone BRTO for GVs. METHODS: This single-center, retrospective study included 57successful patients out of 60 patients who underwent BRTO for GVs from December 2005 to September 2018. We examined the indicators of HFR (e.g., encephalopathy and ascites statuses, serum total bilirubin and albumin levels, % prothrombin time, and Child-Pugh and albumin-bilirubin [ALBI] scores) during 3 years of follow-up after BRTO. We analyzed survival using the Kaplan-Meier method and identified the independent prognostic factors via multivariate analyses. RESULTS: GVs disappeared in all patients who were successfully treated by BRTO. At 3 years after BRTO, serum albumin levels were significantly elevated (from 3.3 to 4.0 g/dL, P = 0.008), while Child-Pugh and ALBI scores were significantly decreased (from 7.0 to 5.7, P = 0.043, and from -1.94 to -2.60, P = 0.006, respectively). The median survival time among all patients was 2207 days; the survival rates after BRTO were 87.0% at 1 year, 81.8% at 3 years, 67.3% at 5 years, and 44.1% at 10 years. Multivariate analyses revealed that ascites, hepatic encephalopathy, and malignant neoplasms were independently associated with poor prognosis. CONCLUSION: BRTO for GVs has a favorable effect on long-term HFR.

[A case of liver abscess caused by hypermucoviscous Klebsiella pneumoniae with septic pulmonary embolism].

A 69-year-old man consulted a local doctor because of a chief complaint of fever and anorexia. CT showed a giant liver mass of the right hepatic lobe and multiple pulmonary nodules. The patient was admitted to our hospital. We punctured the liver mass, obtaining pus, and as gram-negative bacilli were detected from both blood and pus cultures, a liver abscess with septic pulmonary embolism was diagnosed. Following a positive string test, we identified the pathogenic bacteria as hypermucoviscous Klebsiella pneumoniae, which is highly invasive to the tissues. The patient showed improvement following the administration of an antimicrobial agent (Meropenem) and multiple abscess drainage procedures.

Pushing TC to 27.5 K in a heavy atom radical ferromagnet.

In the solid state the iodo-substituted bisdiselenazolyl radical 1c orders as a ferromagnet with TC = 10.5 K. With the application of pressure TC rises rapidly, reaching a value of 27.5 K at 2.4 GPa. The accompanying structural and magnetic changes have been examined by high resolution powder X-ray diffraction and by DFT calculations of magnetic exchange interactions.

Large enhancement of superconducting transition temperature in single-element superconducting rhenium by shear strain.

Finding a physical approach for increasing the superconducting transition temperature (Tc) is a challenge in the field of material science. Shear strain effects on the superconductivity of rhenium were investigated using magnetic measurements, X-ray diffraction, transmission electron microscopy, and first-principles calculations. A large shear strain reduces the grain size and simultaneously expands the unit cells, resulting in an increase in Tc. Here we show that this shear strain approach is a new method for enhancing Tc and differs from that using hydrostatic strain. The enhancement of Tc is explained by an increase in net electron-electron coupling rather than a change in the density of states near the Fermi level. The shear strain effect in rhenium could be a successful example of manipulating Bardeen-Cooper-Schrieffer-type Cooper pairing, in which the unit cell volumes are indeed a key parameter.

The metallic state in neutral radical conductors: dimensionality, pressure and multiple orbital effects.

Pressure-induced changes in the solid-state structures and transport properties of three oxobenzene-bridged bisdithiazolyl radicals 2 (R = H, F, Ph) over the range 0-15 GPa are described. All three materials experience compression of their π-stacked architecture, be it (i) 1D ABABAB π-stack (R = Ph), (ii) quasi-1D slipped π-stack (R = H), or (iii) 2D brick-wall π-stack (R = F). While R = H undergoes two structural phase transitions, neither of R = F, Ph display any phase change. All three radicals order as spin-canted antiferromagnets, but spin-canted ordering is lost at pressures <1.5 GPa. At room temperature, their electrical conductivity increases rapidly with pressure, and the thermal activation energy for conduction Eact is eliminated at pressures ranging from ∼3 GPa for R = F to ∼12 GPa for R = Ph, heralding formation of a highly correlated (or bad) metallic state. For R = F, H the pressure-induced Mott insulator to metal conversion has been tracked by measurements of optical conductivity at ambient temperature and electrical resistivity at low temperature. For R = F compression to 6.2 GPa leads to a quasiquadratic temperature dependence of the resistivity over the range 5-300 K, consistent with formation of a 2D Fermi liquid state. DFT band structure calculations suggest that the ease of metallization of these radicals can be ascribed to their multiorbital character. Mixing and overlap of SOMO- and LUMO-based bands affords an increased kinetic energy stabilization of the metallic state relative to a single SOMO-based band system.

A ferromagnetically coupled Fe42 cyanide-bridged nanocage.

Self-assembly of artificial nanoscale units into superstructures is a prevalent topic in science. In biomimicry, scientists attempt to develop artificial self-assembled nanoarchitectures. However, despite extensive efforts, the preparation of nanoarchitectures with superior physical properties remains a challenge. For example, one of the major topics in the field of molecular magnetism is the development of high-spin (HS) molecules. Here, we report a cyanide-bridged magnetic nanocage composed of 18 HS iron(III) ions and 24 low-spin iron(II) ions. The magnetic iron(III) centres are ferromagnetically coupled, yielding the highest ground-state spin number (S = 45) of any molecule reported to date.

Molecular motor-driven abrupt anisotropic shape change in a single crystal of a Ni complex.

Many molecular machines with controllable molecular-scale motors have been developed. However, transmitting molecular movement to the macroscopic scale remains a formidable challenge. Here we report a single crystal of a Ni complex whose shape changes abruptly and reversibly in response to thermal changes at around room temperature. Variable-temperature single-crystal X-ray diffraction studies show that the crystalline shape change is induced by an unusual 90° rotation of uniaxially aligned oxalate molecules. The oxalate dianions behave as molecular-scale rotors, with their movement propagated through the entire crystalline material via intermolecular hydrogen bonding. Consequently, the subnanometre-scale changes in the oxalate molecules are instantly amplified to a micrometre-scale contraction or expansion of the crystal, accompanied by a thermal hysteresis loop. The shape change in the crystal was clearly detected under an optical microscope. The large directional deformation and prompt response suggest a role for this material in microscale or nanoscale thermal actuators.

Pressure-induced enhancement of magnetic-ordering temperature in an organic radical to 70 K: a magnetostructural correlation.

The structure of the canted antiferromagnet ß-p-NCC(6)F(4)CNSSN (1) was determined from synchrotron powder-diffraction studies in the pressure range 0-21.6 kbar. Radical 1 crystallizes in the orthorhombic space group Fdd2, but undergoes an asymmetric contraction of the unit-cell size with increasing pressure. At the molecular level, this contraction of the unit cell is simultaneously accommodated by: 1) an increase in twist angle between aryl and heterocyclic rings; and 2) a shortening of the intermolecular S···N contacts, which propagate the magnetic-exchange pathway. DFT calculations based on the structures in this pressure range revealed an increase in the magnetic-exchange interaction (J) with increasing pressure, and an excellent correlation was observed between J and the magnetic-ordering temperature, which increased from 36 K at ambient pressure up to 70 K at 16 kbar.

From magnets to metals: the response of tetragonal bisdiselenazolyl radicals to pressure.

The bromo-substituted bisdiselenazolyl radical 4b (R(1) = Et, R(2) = Br) is isostructural with the corresponding chloro-derivative 4a (R(1) = Et, R(2) = Cl), both belonging to the tetragonal space group P(4)2(1)m and consisting of slipped π-stack arrays of undimerized radicals. Variable temperature, ambient pressure conductivity measurements indicate a similar room temperature conductivity near 10(-4) S cm(-1) for the two compounds, but 4b displays a slightly higher thermal activation energy E(act) (0.23 eV) than 4a (0.19 eV). Like 4a, radical 4b behaves as a bulk ferromagnet with an ordering temperature of T(C) = 17.5 K. The coercive field H(c) (at 2 K) of 1600 Oe for 4b is, however, significantly greater than that observed for 4a (1370 Oe). High pressure (0-15 GPa) structural studies on both compounds have shown that compression reduces the degree of slippage of the π-stacks, which gives rise to changes in the magnetic and conductive properties of the radicals. Relatively mild loadings (<2 GPa) cause an increase in T(C) for both compounds, that of 4b reaching a maximum value of 24 K; further compression to 5 GPa leads to a decrease in T(C) and loss of magnetization. Variable temperature and pressure conductivity measurements indicate a decrease in E(act) with increasing pressure, with eventual conversion of both compounds from a Mott insulating state to one displaying weakly metallic behavior in the region of 7 GPa (for 4a) and 9 GPa (for 4b).

Chemical and physical characterizations of spinel ferrite nanoparticles containing Nd and B elements.

We first succeeded in synthesizing ferrite nanoparticles containing Nd and B elements by a chemical route using a polyol process. The lattice constants of the ferrite nanoparticles were equivalent to 8.39Å of the lattice constant for Fe(3)O(4) with the spinel structure in a bulk state independently of the size in diameter and composition (Fe:Nd:B). The size in diameter was actually dominated by the amount of ligands (oleic acid and oleylamine) coating the nanoparticles and easily tuned by changing refluxing-time under reaction. The spinel-structured ferrite nanoparticles containing Nd and B elements showed large coercivity as compared to Fe(3)O(4) nanoparticles with the spinel structure, which were prepared by the same chemical method. By doping Nd and B elements into the spinel structure of ferrite, magnetic anisotropy increased in comparison with Fe(3)O(4) nanoparticles. According to the analysis of magnetization curve using the modified Langevin function, the ferrite nanoparticles displayed the coexistence of superparamagnetic and antiferromagnetic phases. The ferrite nanoparticles containing Nd and B elements exhibited magnetic core/shell structure on the basis of various magnetic properties. The interface effect between the superparamagnetic core and antiferromagnetic shell might enhance the effective magnetic anisotropy of the ferrite nanoparticles containing Nd and B elements.

Heavy atom ferromagnets under pressure: structural changes and the magnetic response.

Application of physical pressure to a ferromagnetic bisdiselenazolyl radical leads to a decrease in pi-stack slippage. Initially, this leads to an increase in the ferromagnetic ordering temperature T(C), which reaches a maximum of 21 K near 1 GPa. At higher pressures, as the pi-stacks become more nearly superimposed, the value of T(C) diminishes.

Response of superconductivity and crystal structure of LiFeAs to hydrostatic pressure.

On the application of hydrostatic pressures of up to 1.3 GPa, the superconducting transition temperatures (T(c)) of samples of LiFeAs are lowered approximately monotonically at approximately -2 K GPa(-1). Measurements of the X-ray powder diffraction pattern at hydrostatic pressures of up to 17 GPa applied by a He gas pressure medium in a diamond anvil cell reveal a bulk modulus for LiFeAs of 57.3(6) GPa which is much smaller than that of other layered arsenide and oxyarsenide superconductors. LiFeAs also exhibits much more isotropic compression than other layered iron arsenide superconductors. The higher and more isotropic compressibility is presumably a consequence of the small size of the lithium ion. At ambient pressure the FeAs(4) tetrahedra are the most compressed in the basal plane of those in any of the superconducting iron arsenides. On increasing the pressure the Fe-Fe distance contracts more rapidly than the Fe-As distance so that the FeAs(4) tetrahedra become even more distorted from the ideal tetrahedral shape. The decrease in T(c) with applied pressure is therefore consistent with the observations that in the iron arsenides and related materials investigated thus far, T(c) is maximized for a particular electron count when the FeAs(4) tetrahedra are close to regular.

Magnetoresistance and microstructure of magnetite nanocrystals dispersed in indium-tin oxide thin films.

Epitaxial indium-tin oxide (ITO) thin films were fabricated on a yttria-stabilized zirconia (YSZ) substrate by pulsed-laser deposition using magnetite (Fe(3)O(4)) nanoparticle dispersed ITO powders as a target. Magnetoresistance of the film at a field of 1 T was 39% at 45 K, and it stayed at 3% above 225 K. The film demonstrated cooling hysteresis in the temperature dependence of direct-current magnetization. Transmission electron microscopy revealed that phase-separated Fe(3)O(4) nanocrystals with widths of approximately 40-150 nm and heights of approximately 10-25 nm precipitated and grew epitaxially on the substrate in the film. Both the Fe(3)O(4)(111) and ITO(001) planes were parallel to the YSZ(001) plane. The Fe(3)O(4)(11-2) and -(1-10) planes were parallel to the ITO(100) and -(010) planes, respectively, and the planes connected smoothly at the grain boundary. The contour map of the electron density for the Fe(3)O(4)(111) plane by the first-principles electronic structure computation was similar to that for the ITO(001) plane. The [111]-oriented Fe(3)O(4) nanocrystals played the role of spin aligner for charge carriers of the epitaxial ITO film.

Pressure response of three-dimensional cyanide-bridged bimetallic magnets.

Effects of pressure on the structures and magnetic properties of three types of 3-D cyanide-bridged bimetallic coordination polymer magnets, MnIICrIII ferrimagnet [Mn(en)]3[Cr(CN)6]2.4H2O (1; en = ethylenediamine), NiIICrIII ferromagnet [Ni(dipn)]3[Cr(CN)6]2.3H2O (2; dipn = N,N-di(3-aminopropyl)amine), and NiIIFeIII ferromagnet [Ni(dipn)]2[Ni(dipn)(H2O)][Fe(CN)6]2.11H2O (3), were systematically examined under hydrostatic pressure up to 19.8 GPa using a piston-cylinder-type pressure cell and a diamond anvil cell. The ferrimagnet 1 showed the reversible crystalline-to-amorphous-like phase change, and the magnetic phase transition temperature (TC) was reversibly changed from 69 K at 0 GPa to 126 K at 4.7 GPa. At higher pressure, the net magnetization was suppressed with increasing pressure, and the magnetic state at 19.8 GPa was assumed to be paramagnetic. The initial ferrimagnetic phase of 1 was not recovered after releasing the pressure from 19.8 GPa. The magnetic phase of 2 was reversibly converted between ferromagnetic and paramagnetic-like phase in the range 0

Interpenetrated three-dimensional MnIIMIII ferrimagnets, [Mn(4dmap)4]3[M(CN)6]2.10 H2O (M=Cr, Mn): structures, magnetic properties, and pressure-responsive magnetic modulation.

Two novel cyanide-bridged ferrimagnets, [Mn(4dmap)(4)](3)[M(CN)(6)](2)- 10 H(2)O (4dmap=4-dimethylaminopyridine, M=Cr (1) and Mn (2)), have been prepared from the reaction of MnCl(2)4 H(2)O, a monodentate coligand (4dmap), with K(3)[M(CN)(6)]. X-ray crystallographic results show that these are isomorphous, and form a unique twofold interpenetrated three-dimensional framework with a triconnected 6.10(2) net. The framework contains two types of one-dimensional channel: hexagonal channels based on a cyanide-bridged Mn(6)M(6) hexagon, and triangle channels segmented by CN-Mn-NC linkages, which are filled with lattice water molecules. The dimethylamino groups of the 4dmap coligands are located around a pore and form the basic inner space. Variable-temperature X-ray powder diffraction and thermogravimetric analysis results show that the frameworks of both compounds are susceptible to dehydration through the loss of strongly hydrogen-bonded lattice water molecules. Magnetic measurements on both compounds show a ferrimagnetic ordering occurs at low temperature, T(C)=17 K for 1 and 6 K for 2. Application of hydrostatic pressure showed a positive effect on the magnetic ordering. Both values of T(C) increased linearly, to 25 K for 1 and 15 K for 2 at 1.0 GPa. The magnetic properties of both compounds were reversibly modulated by the external stress.