Expanded quantum vortex liquid regimes in the electron nematic superconductors FeSe1-xSx and FeSe1-xTex.

The quantum vortex liquid (QVL) is an intriguing state of type-II superconductors in which intense quantum fluctuations of the superconducting (SC) order parameter destroy the Abrikosov lattice even at very low temperatures. Such a state has only rarely been observed, however, and remains poorly understood. One of the key questions is the precise origin of such intense quantum fluctuations and the role of nearby non-SC phases or quantum critical points in amplifying these effects. Here we report a high-field magnetotransport study of FeSe1-xSx and FeSe1-xTex which show a broad QVL regime both within and beyond their respective electron nematic phases. A clear correlation is found between the extent of the QVL and the strength of the superconductivity. This comparative study enables us to identify the essential elements that promote the QVL regime in unconventional superconductors and to demonstrate that the QVL regime itself is most extended wherever superconductivity is weakest.

Magnetically Hidden State on the Ground Floor of the Magnetic Devil's Staircase.

We investigated the low-temperature and high-field thermodynamic and ultrasonic properties of SrCu_{2}(BO_{3})_{2}, which exhibits various plateaux in its magnetization curve above 27 T, called a magnetic Devil's staircase. The results of the present study confirm that magnetic crystallization, the first step of the staircase, occurs above 27 T as a first-order transition accompanied by a sharp singularity in heat capacity C_{p} and a kink in the elastic constant. In addition, we observe a thermodynamic anomaly at lower fields around 26 T, which has not been previously detected by any magnetic probes. At low temperatures, this magnetically hidden state has a large entropy and does not exhibit Schottky-type gapped behavior, which suggests the existence of low-energy collective excitations. Based on our observations and theoretical predictions, we propose that magnetic quadrupoles form a spin-nematic state around 26 T as a hidden state on the ground floor of the magnetic Devil's staircase.

Collaborative Research Activities of the Arase and Van Allen Probes.

This paper presents the highlights of joint observations of the inner magnetosphere by the Arase spacecraft, the Van Allen Probes spacecraft, and ground-based experiments integrated into spacecraft programs. The concurrent operation of the two missions in 2017-2019 facilitated the separation of the spatial and temporal structures of dynamic phenomena occurring in the inner magnetosphere. Because the orbital inclination angle of Arase is larger than that of Van Allen Probes, Arase collected observations at higher L -shells up to L ∼ 10 . After March 2017, similar variations in plasma and waves were detected by Van Allen Probes and Arase. We describe plasma wave observations at longitudinally separated locations in space and geomagnetically-conjugate locations in space and on the ground. The results of instrument intercalibrations between the two missions are also presented. Arase continued its normal operation after the scientific operation of Van Allen Probes completed in October 2019. The combined Van Allen Probes (2012-2019) and Arase (2017-present) observations will cover a full solar cycle. This will be the first comprehensive long-term observation of the inner magnetosphere and radiation belts.

Penetration of MeV electrons into the mesosphere accompanying pulsating aurorae.

Pulsating aurorae (PsA) are caused by the intermittent precipitations of magnetospheric electrons (energies of a few keV to a few tens of keV) through wave-particle interactions, thereby depositing most of their energy at altitudes ~ 100 km. However, the maximum energy of precipitated electrons and its impacts on the atmosphere are unknown. Herein, we report unique observations by the European Incoherent Scatter (EISCAT) radar showing electron precipitations ranging from a few hundred keV to a few MeV during a PsA associated with a weak geomagnetic storm. Simultaneously, the Arase spacecraft has observed intense whistler-mode chorus waves at the conjugate location along magnetic field lines. A computer simulation based on the EISCAT observations shows immediate catalytic ozone depletion at the mesospheric altitudes. Since PsA occurs frequently, often in daily basis, and extends its impact over large MLT areas, we anticipate that the PsA possesses a significant forcing to the mesospheric ozone chemistry in high latitudes through high energy electron precipitations. Therefore, the generation of PsA results in the depletion of mesospheric ozone through high-energy electron precipitations caused by whistler-mode chorus waves, which are similar to the well-known effect due to solar energetic protons triggered by solar flares.

Anisotropic Fully Gapped Superconductivity Possibly Mediated by Charge Fluctuations in a Nondimeric Organic Complex.

We investigate low-temperature electronic properties of the nondimeric organic superconductor ß^{''}-(ET)_{4}[(H_{3}O)Ga(C_{2}O_{4})_{3}]PhNO_{2}. By examining ultrasonic properties, charge disproportionation (CD) without magnetic field dependence is detected below T_{CD}∼8 K just above the superconducting critical temperature T_{c}∼6 K. From quantum oscillations in high fields, we find variation in the Fermi surface and mass enhancement induced by the CD. Heat capacity studies elucidate that the superconducting gap function is fully gapped in the Fermi surface, but anisotropic with fourfold symmetry. We point out that the pairing mechanism of the superconductivity is possibly dominated by charge fluctuations.

Oxygen torus and its coincidence with EMIC wave in the deep inner magnetosphere: Van Allen Probe B and Arase observations.

We investigate the longitudinal structure of the oxygen torus in the inner magnetosphere for a specific event found on 12 September 2017, using simultaneous observations from the Van Allen Probe B and Arase satellites. It is found that Probe B observed a clear enhancement in the average plasma mass (M) up to 3-4 amu at L = 3.3-3.6 and magnetic local time (MLT) = 9.0 h. In the afternoon sector at MLT ~ 16.0 h, both Probe B and Arase found no clear enhancements in M. This result suggests that the oxygen torus does not extend over all MLT but is skewed toward the dawn. Since a similar result has been reported for another event of the oxygen torus in a previous study, a crescent-shaped torus or a pinched torus centered around dawn may be a general feature of the O+ density enhancement in the inner magnetosphere. We newly find that an electromagnetic ion cyclotron (EMIC) wave in the H+ band appeared coincidently with the oxygen torus. From the lower cutoff frequency of the EMIC wave, the ion composition of the oxygen torus is estimated to be 80.6% H+, 3.4% He+, and 16.0% O+. According to the linearized dispersion relation for EMIC waves, both He+ and O+ ions inhibit EMIC wave growth and the stabilizing effect is stronger for He+ than O+. Therefore, when the H+ fraction or M is constant, the denser O+ ions are naturally accompanied by the more tenuous He+ ions, resulting in a weaker stabilizing effect (i.e., larger growth rate). From the Probe B observations, we find that the growth rate becomes larger in the oxygen torus than in the adjacent regions in the plasma trough and the plasmasphere.

[Lateral femoral circumflex artery for coronary artery bypass surgery in a patient receiving hemodialysis: report of a case].

A 59-year-old man receiving hemodialysis had a 2-vessel coronary disease. We performed double coronary artery bypass grafting with the left internal thoracic artery to the left anterior descending artery, and the composite graft of right internal thoracic artery and lateral femoral circumflex artery to the right coronary artery. Postoperative coronary angiogram showed that the LFCA bypass graft was widely patent and supplied sufficient blood to the anastomosed vessel. There was no stenosis at the anastomotic site. He had no postoperative complication. Long-term follow-up and more cases is necessary to establish the usefulness of LFCA as an arterial free graft for coronary revascularization in patients receiving hemodialysis.

Studies on the structure-function relationship of the HNK-1 associated glucuronyltransferase, GlcAT-P, by computer modeling and site-directed mutagenesis.

All members of a glucuronyltransferase (GlcAT) gene family cloned to date contain four conserved regions (modules I-IV), which are widely located in the catalytic domain. In order to understand the biological significance of these modules, we investigated the structure-function relationship of GlcAT-P by means of the combination of site-directed mutagenesis and computer aided three-dimensional modeling. The wild-type and mutant GlcAT-Ps were expressed in Escherichia coli as glutathione-S-transferase (GST)-fused soluble proteins. Most of the mutants in which a polar amino acid within the modules was replaced with alanine lost their transferase activity almost completely, while all of the mutants in which the replacement was outside these modules retained the original catalytic activity. A three-dimensional (3-D) model of GlcAT-P was constructed by computer simulation with the three-dimensional structure of adenylate kinase (1AKE) as a template. This model predicted that the large catalytic domain of GlcAT-P forms a globular shape with a Rossmann-fold motif consisting of five alpha-helix and beta-sheet repeats. The putative catalytic pocket consisting mainly of modules I-III is surrounded by a cluster of polar amino acids, which are essential for the transferase activity and also for the binding to the acceptor substrate (essential amino acids), asialo-orosomucoid. There is the second cluster of essential amino acids almost on the opposite surface of the molecule, in which an aspartic acid repeat (DDD) is located. The biological significance of the second cluster is currently not clear but it may be associated with the interaction of the enzyme with modulation molecules, manganese and membrane phospholipids.

Substituted 3-phenylsulfonylquinazoline-2,4-dione derivatives as novel nonpeptide inhibitors of human heart chymase.

A series of 3-phenylsulfonylquinazoline-2,4-dione derivatives have been synthesized and evaluated for their ability to inhibit human heart chymase. The structure-activity relationship studies on these compounds gave the following results. The phenyl moiety of quinazoline participates in a hydrophobic interaction where an optimum size is required. In this moiety, 7-chloroquinazoline is the best moiety for inhibiting chymase, chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted with hydrophobic electron-withdrawing groups at the 4-position potentiated the activity. Anthranil moiety also enhanced the activity. Pyridylmethyl and N-pyridylacetamide at the 1-position gave an IC50 in the order of 10(-8)M. Molecular modeling studies on the interaction of 7-chloro-3-(4-chlorophenylsulfonyl) quinazoline-2,4(1H, 3H)-dione (4) with the active site of human heart chymase suggested that the phenyl moiety of quinazoline interacts with the hydrophobic P1 pocket, the 3-phenylsulfonyl moiety resides in the S1'-S2' subsites, the moiety at the 1-position locates in the S2-S3 subsites and the 4-carbonyl and 3-sulfonyl group interact with the oxyanion hole and the His57 side-chain of chymase, respectively.

The role of water molecules in the deacylation of acylated structures of class A beta-lactamase.

Molecular dynamics simulation of the penicillin- and penem-acylated enzymes reveals that the conformational flexibility of the acyl moieties in the binding cleft and the conformational change of the acyl moieties are crucial for deacylation. The water molecule adjacent to the Glu 166 residue is not the nucleophile for deacylation, but construction of a model of the oxyanion tetrahedral intermediate suggested a plausible role of the water molecule as a proton donor for the oxyanion to facilitate the deacylation.

5,6-Cis-penems: broad-spectrum anti-methicillin-resistant Staphylococcus aureus beta-lactam antibiotics.

5,6-cis-Penem derivatives have been synthesized and evaluated as anti-MRSA antibiotics. The cis-penems 5 and 6 showed potent activities against not only MRSA but also a wide variety of bacteria including beta-lactamase-producing microorganisms. These compounds were designed to have high affinity to the penicillin-binding protein 2a of MRSA and to form stable acyl intermediates with beta-lactamases by blocking the deacylating water molecule.

Substituted 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives as novel nonpeptide inhibitors of human heart chymase.

A series of 3-(phenylsulfonyl)-1-phenylimidazolidine-2,4-dione derivatives have been synthesized and evaluated for their ability to selectively inhibit human heart chymase. The structure-activity relationship studies on these compounds gave the following results. The 1-phenyl moiety participates in a hydrophobic interaction where an optimum size is required. At this position, 3,4-dimethylphenyl is the best moiety for inhibiting chymase and showed high selectivity compared with chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted with hydrogen-bond acceptors such as nitrile and methoxycarbonyl enhances its activity. Molecular-modeling studies on the interaction of 3-[(4-chlorophenyl)sulfonyl]-1-(4-chlorophenyl)-imidazolidine-2,4-dione (29) with the active site of human heart chymase suggested that the 1-phenyl moiety interacts with the hydrophobic P1 pocket, the 3-phenylsulfonyl moiety resides in the S1'-S2' subsites, and the 4-carbonyl of the imidazolidine ring and sulfonyl group interact with the oxyanion hole and the His-45 side chain of chymase, respectively. The complex model is consistent with the structure-activity relationships.

Structure-activity relationships of penem antibiotics: crystallographic structures and implications for their antimicrobial activities.

Twelve closely related crystal structures of the penem derivatives revealed a characteristic short contact of the oxygen atom in the C2 side-chains with the S1 atom. The side-chain conformations of the crystal structures showed a good correlation with the antimicrobial activity. In particular, the penems which show high antimicrobial activity have similar torsion angles for S1-C2-C1'-C2', suggesting that the disposition of the C2' atom would be important for binding to penicillin-interacting enzymes. Two conformations of the C6 hydroxyethyl group were observed in the crystal structures. Of those two, the conformation with a larger torsion angle (delta = 179.2 degrees) is deduced to be the enzyme-bound conformation in the Michaelis complex.

Adsorption and Recovery of Ionic Surfactants by beta-Cyclodextrin Polymer

The adsorption and recovery of ionic surfactants, such as dodecylbenzenesulfonic acid (DBS) and benzalkonium chloride (BKC), from an aqueous solution were studied using the beta-cyclodextrin polymer (beta-CDP). BKC always demonstrated a higher adsorption efficiency than DBS in batch tests, isotherms, and column tests. The adsorption characteristics of the surfactants seemed to be caused by inclusion into beta-CD, and they were easily determined using the Langmuir adsorption isotherm. Furthermore, the surfactants adsorbed by beta-CDP were easily released by shaking it with a mixture of water and methanol. Recovery efficiency was dependent on the mixture ratio of the solvent, and regenerated beta-CDP was reusable as an adsorbent.

Modeling study on a hydrolytic mechanism of class A beta-lactamases.

Comparison of the hydrogen-bond networks at the active site in the crystallographic structures reported for class A beta-lactamases revealed an importance of a switch of the hydrogen-bond network for the catalytic process. Taking account of the conformational mobility of the Lys73 residue, we have constructed putative complex models for beta-lactam antibiotics and the enzymes in the multistep hydrolysis which consists of a Michaelis complex, an acyl-enzyme, and a tetrahedral oxyanion for deacylation. In the acylation, the C3 carboxylate of penicillin derivatives would participate in activation of the Ser130 hydroxyl group and then the oxyanion of the Ser130 residue would deprotonate the ammonium group of the Lys73 residue which will act as a general base for activation of the Ser70 residue. In the deacylation, the deacylating water molecule would be accommodated during a conformational change of the acyl moiety without a structural change of the active-site residues and the unprotonated N4 atom of the penicillins would act as a general base to activate the water molecule. This catalytic process provided a new account for the stability of the acyl-enzyme complexes. This substrate-assisted mechanism would also be extended to a hydrolytic mechanism of class C enzymes.

[The interactive effect of initial position and threat to freedom on psychological reactance].

An experiment was conducted to examine which was crucial for the reactance effect on attitude change: discrepancy, initial position or prerequisite conditions for reactance arousal. Initial receiver attitudes were one of the five levels: moderate or extreme agreement (the least discrepancy), slight agreement, neutral, slight disagreement, and moderate or extreme disagreement (the most discrepancy), and threat to attitudinal freedom was manipulated. Prerequisite conditions for reactance arousal were also measured. Threat manipulation significantly reduced opinion change only among receivers at neutral or moderate/extreme disagreement position. In addition, examination of prerequisites showed that compliance in high threat condition was significantly less for receivers who had been uncertain about their own initial position and had perceived the issue important (freedom-of-choice group) and those who had perceived the attacked position as both possible and important (freedom-of-position group). Theoretical and practical significance of prerequisites for reactance arousal is discussed.

Cloning and sequence of the gene encoding a cefotaxime-hydrolyzing class A beta-lactamase isolated from Escherichia coli.

Escherichia coli TUH12191, which is resistant to piperacillin, cefazolin, cefotiam, ceftizoxime, cefuzonam, and aztreonam but is susceptible to cefoxitin, latamoxef, flomoxef, and imipenem, was isolated from the urine of a patient treated with beta-lactam antibiotics. The beta-lactamase (Toho-1) purified from the bacteria had a pI of 7.8, had a molecular weight of about 29,000, and hydrolyzed beta-lactam antibiotics such as penicillin G, ampicillin, oxacillin, carbenicillin, piperacillin, cephalothin, cefoxitin, cefotaxime, ceftazidime, and aztreonam. Toho-1 was markedly inhibited by beta-lactamase inhibitors such as clavulanic acid and tazobactam. Resistance to beta-lactams, streptomycin, spectinomycin, sulfamethoxazole, and trimethoprim was transferred by conjugational transfer from E. coli TUH12191 to E. coli ML4903, and the transferred plasmid was about 58 kbp, belonging to incompatibility group M. The cefotaxime resistance gene for Toho-1 was subcloned from the 58-kbp plasmid by transformation of E. coli MV1184. The sequence of the gene for Toho-1 was determined, and the open reading frame of the gene consisted of 873 or 876 bases (initial sequence, ATGATG). The nucleotide sequence of the gene (DDBJ accession number D37830) was found to be about 73% homologous to the sequence of the gene encoding a class A beta-lactamase produced by Klebsiella oxytoca E23004. According to the amino acid sequence deduced from the DNA sequence, the precursor consisted of 290 or 291 amino acid residues, which contained amino acid motifs common to class A beta-lactamases (70SXXK, 130SDN, and 234KTG). Toho-1 was about 83% homologous to the beta-lactamase mediated by the chromosome of K. oxytoca D488 and the beta-lactamase mediated by the plasmid of E. coli MEN-1. Therefore, the newly isolated beta-lactamase Toho-1 produced by E. coli TUH12191 is similar to beta-lactamases produced by K. oxytoca D488, K. oxytoca E23004, and E. coli MEN-1 rather than to mutants of TEM or SHV enzymes. Toho-1 has shown the highest degree of similarity to K. oxytoca class A beta-lactamase. Detailed comparison of Toho-1 with other beta-lactamases implied that replacement of Asn-276 by Arg with the concomitant substitution of Thr for Arg-244 is an important mutation in the extension of the substrate specificity.

On the conformation of Phe78 of a chromoprotein antibiotic, neocarzinostatin.

A structure of neocarzinostatin, an antitumor chromoprotein antibiotic, has been built using X-ray crystallographic data and NMR data, particularly NOE data observed between the apoprotein and the chromophore. Chemical shift changes of protons of the chromophore upon binding to the apoprotein indicated that the aromatic plane of Phe52 has the conformation almost perpendicular to the C-2-C-3 triple bond of the core of the chromophore while Phe78 takes multiple conformations in solution although one of the stable conformations has been assigned for Phe78 in a crystal structure.

The specific inhibition of crystal growth of monohydrogen potassium L-tartrate by d-catechin.

Crystal growth of monohydrogen potassium L-tartrate in an ethanolic aqueous solution was specifically inhibited by d-catechin, but not by either its epimeric isomer at C3, l-epicatechin or by gallic acid and caffeic acid. 3D-Structure similarity search of d-catechin with two molecules of the tartrate and docking study of d-catechin with the crystal model of the tartrate suggested that d-catechin mimics a structure consisting of the two tartrate molecules in the inhibition. Differences in the conformation of the catechol moieties of d-catechin and l-epicatechin may explain the distinct inhibitory effects of the epimeric isomers.