ab initio Study of Strain-Induced Ferroelectricity in SrTiO3

Valley lines on total-energy surfaces for the zone-center distortions of free-standing and in-plane strained SrTiO3 are investigated with a newly developed first-principles structure optimization technique [Jpn. J. Appl. Phys. vol.43 (2004), p.6785]. The results of numerical calculations confirmed that the ferroelectricity is induced, and the Curie temperature is increased, by applying biaxial compressive or tensile strains. Along the distortion, strong nonlinear coupling between the soft- and hard-modes is demonstrated.Comment: 15 pages, 10 figures, submitted to Jpn. J. Appl. Phy

Ab initio Study of Valley Line on a Total-Energy Surface for Zone-Center Distortions of Ferroelectric Perovskite Oxides BaTiO3 and PbTiO3

An ab initio structure optimization technique is newly developed to determine the valley line on a total-energy surface for zone-center distortions of ferroelectric perovskite oxides and is applied to barium titanate BaTiO3 and lead titanate PbTiO3. The proposed technique is an improvement over King-Smith and Vanderbilt's scheme [Phys. Rev. B 49, p.5828 (1994)] of evaluating total energy as a function of the amplitude of atomic displacements. The results of numerical calculations show that total energy can be expressed as a fourth-order function of the amplitude of atomic displacements in BaTiO3 but not in PbTiO3.Comment: 4 pages, 5 figure

Algebra of Hyperbolic Band Theory under Magnetic Field

We explore algebras associated with the hyperbolic band theory under a magnetic field for the first time. We define the magnetic Fuchsian group associated with a higher genus Riemann surface. By imposing the magnetic bounday conditions for the hyperbolic Bloch states, we construct the hyperbolic magnetic Bloch states and investigate their energy spectrum. We give a connection between such magnetic Bloch states and automorphic forms. Our theory is a general extension of the conventional algebra associated with the band theory defined on a Euclidean lattice/space into that of the band theory on a general hyperbolic lattice/Riemann surface.Comment: 21 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:2104.1331

Role of left ventricular regional nonuniformity in hypertensive diastolic dysfunction

AbstractObjectives. This study investigated 1) the role of left ventricular diastolic nonuniformity in hypertensive left ventricular diastolic dysfunction, and 2) the effect of a calcium channel antagonist on diastolic nonuniformity in hypertensive and normotensive subjects.Background. Augmented left ventricular nonuniformity contributes to diastolic dysfunction in hypertrophic cardiomyopathy, Impaired left ventricular diastolic function with preserved systolic function has been recognized in hypertension. Therefore, abnormal ventricular regional nonuniformity might also be involved in hypertensive diastolic dysfunction in a milder form of hypertrophy.Methods. Thirteen patients with established hypertension underwent radionuclide ventriculography before and after nifedipine administration. Indexes of left ventricular function were derived by computer analysis of the time-activityy cure. After a compter subdivided the left ventricle into four regions, a timeactivity curve of each region was constructed to determine an index of left ventricular diastolic nonuniformity. This index was calculated as the sum of the absolute values of time difference between global and regional filling in the septal, the apical and the literal region. Tea normotensive subjects were studied for comparison, Echocardiography was performed in both group,Results. The two group were matched for age, gender, heart rate, echocardiographic dimensions and systolic function. In the hypertensive group, left ventricular diastolic filling index were impaired, with a negative correlation between peak filling rate and the diastolic nonuniformity index. Although the change in ejection fraction after nifedipine administration was similar in the two groups, the increase in filling rate was larger in the hypertensive patients. The diastolic nonuniformity index decreased after nifedipine in the hypertensive but not in the control group. This decrease correlated with improvad peak filling rate in the hypertensive group.Conclusions. In hypertensive with preserved systolic function, left ventricular diastoiic nonuniformity increases causing early diastolic dysfunction. Decreased diastolic nonuniformity after pharmacologic intervention contributes to lessened ventricular filling dysfunction, regardless of changes in conditions in hypertension. Thus, diastolic nonuniformity is an important determinant of left ventricular abnormality and be a target of pharmacologic intervention in hypertensive patients

Effect of Cationic Micellar Reaction Field on Reaction Kinetics of Meisenheimer σ-Complex Formation between 1,3,5-Trinitrobenzene and Hydroxide Ion

Kinetic studies were done by using stopped-flow method for the Meisenheimer σ-complex formation reaction between 1,3,5-trinitrobenzene (TNB) and hydroxide ion in cationic micellar solutions of dodecyl-trimethylammonium bromide (DTAB), myristyltrimethylammonium bromide (MyTAB) and cetyltrimethylammonium bromide (CTAB) dissolved in aqueous solution, for the purpose of elucidating the influence of the microscopic heterogeneity of reaction field. The reaction rate analysis based on a pseudo-phase ion exchange model led us to a conclusion that the partition of reactant molecules between the micelle and water phase, and ion exchange between hydroxide ion and bromide ion existing as counter ions of cationic micellar surface were important. On the activation process, the enthalpy-entropy compensation relationships worked over the wide range of surfactant concentration. The derived isokinetic temperature, T_ revealed that in CTAB the reaction might be of enthalpy-control, and that in MyTAB be of entropy-control

Reaction Kinetics of Meisenheimer σ-Complex Formation between 2,4,6-Trinitrophenyl Chloride and Hydroxide Ion in Cationic Micellar Solution

Kinetic study was carried out by using stopped-flow method for the Meisenheimer σ-complex formation reaction between 2,4,6-trinitrophenyl chloride (picryl chloride: Pic-Cl) and hydroxide in aqueous cationic micellar solutions of dodecyltrimethylammonium bromide (DTAB), myristyltrimethylammonium bromide (MyTAB) and cetyltrimethyl-ammonium bromide (CTAB) dissolved in aqueous solution, for the purpose of elucidating the influence of the microscopic heterogeneity of reaction field on activation parameters. The reaction rate analysis based on a pseudo-phase ion exchange model led us to a conclusion that on the activation process the enthalpy-entropy compensation relationships worked over the wide range of surfactant concentration, and that, for the reaction occurring at the micellar surface, a reactant molecule effective to the reaction had to move into some restricted direction

Effect of Acute Hyperoxia and Hypoxia on the Central Blood Volume in Patients with Chronic Pulmonary Diseases

To investigate whether the central blood volume (CBV) reflects the pulmonary vasculature, we measured CBV before and after the inhalation of 100 % or 13 %O2 for 15 min in patients with chronic pulmonary diseases. Using the Stewart-Hamilton technique, we measured CBV using a lung water computer, employing sodium as an indicator. Thirteen patients inhaled 100 % O2, while 8 patients breathed 13 % O2. Hyperoxia increased CBV significantly and the delta change in CBV(△CBV)correlated significantly with the change in total pulmonary resistance index(△TPPI;r=-0.65, p<0.02),the change in mixed venous oxygen tension(△PvO2; r = - 0.58, p < 0.05) and the change in the coefficient of oxygen delivery (△COD;r=0.71, p<0.02). Hypoxic breathing caused little or no change in CBV, but △CBV correlated well with△TPRI(r=-0.74, p<0.05)and△PvO2 (r=0.85,p<0.01)。 Our results suggest that△CBV provides a good index of the pulmonary vascular bed, on which efficient gas-exchange occurs