Determination of the association constant of sulfuric acid

The activities of HC1 and H₂SO₄ in aqueous solutions of HC1-H₂SO₄ and H₂SO₄-HC1O₄, respectively, were measured at 298 K by an electromotive force (emf) method. Using the activity data, the association constant,K*_{H 2SO 4} was calculated as a function of the effective ionic strength of the solution by a method similar to that proposed by Johnson and Pytkowicz. The association constant of H₂SO₄, which corresponds to the reciprocal value of the first ionization constant of H₂SO₄, decreased with an increase in the effective ionic strength and was correlated to the effective ionic strength,I _e (mol dm⁻³), as follows: logK*_{H 2SO 4} = 0.42 - 0.91I_e, 0 I_e1 The mean free activity coefficients of H₂SO₄ were calculated from the association constant of H₂SO₄ and were found to decrease with an increase in the effective ionic strength. Formerly Graduate Student, Department of Metallurgy, Kyoto University.     

Experimental rat model representing both acute and chronic heart failure related to autoimmune myocarditis

The most important clinical manifestation of myocarditis is congestive heart failure. The precise mechanisms of heart failure during myocarditis have not been elucidated because no animal model that would permit in vivo study of hemodynamics in severe active myocarditis has been available. We monitored hemodynamics and left ventricular function in a rat model of experimental autoimmune myocarditis to determine if this model could be useful for the study of in vivo hemodynamics in severe active myocarditis. Lewis rats were immunized with human cardiac myosin suspended in complete Freund's adjuvant. Baseline hemodynamics were measured using an ultraminiature catheter pressure transducer via the right internal carotid artery, 4 weeks after immunization in one group of rats (acute phase) and 3 months after immunization in another group (chronic phase). Untreated rats served as the control group. Hemodynamic measurements were also obtained after infusion of dobutamine in the acute-phase and chronic-phase groups. The heart weight-to-body weight ratios were significantly higher in both the acute-phase group and the chronic-phase group compared with normal control rats. The baseline left ventricular systolic pressure was significantly lower in the chronic phase group than in the control group. Peak dP/dt and peak -dP/dt were significantly lower in both the acute-phase group and the chronic-phase group compared with the control group. Dobutamine significantly increased left ventricular systolic pressure, peak dP/dt, and peak -dP/dt in the chronic-phase group but caused only minor changes in hemodynamic variables in the acute-phase group. In vivo measurements of hemodynamic variables indicated the presence of left ventricular dysfunction in rats with experimental autoimmune myocarditis. This animal model may be useful for the study of both acute heart failure related to acute myocarditis and chronic heart failure due to diffuse myocardial fibrosis.     

Formation of NbC and TaC by solid-state reaction

The formation of NbC and TaC by solid-state reaction of Nb₂O₅ and Ta₂O₅ with carbon, respectively, was studied at 1000 to 1285° C by X-ray diffraction. Factors affecting the formation of the carbides, such as the nature of the reaction vessel, the molar ratio of carbon/oxide, the form of reactant carbon, etc., were examined. By covering the graphite crucible and increasing the molar ratio of carbon to oxide, complete formation of NbC and TaC could be achieved in about 60 min at low temperatures (1170 and 1225° C, respectively). The beneficial effect of covering the crucible is ascribed to the retention of CO which facilitates the reaction at low temperatures. The formation kinetics of NbC and TaC obey a first-order equation, with activation energies of 90 and 93 kcal mol^–1, respectively. Possible mechanisms for the solid-state reactions are discussed.     

In-Plane Fourfold Symmetry of the Upper Critical Field Observed in La(Sr)214 Single Crystals

In order to establish the existence of in-plane anisotropy of the upper critical field H _c2 (), the out-of-plane resistivity _c measurements were performed on La(Sr)214 single crystals with rectangular and cylindrical shape under rotating magnetic field applied within the ab-plane. Although observed _c shows non-sinusoidal twofold symmetry, clear fourfold symmetry was obtained after subtracting twofold sinusoidal component in _c which is due to the unavoidable misalignment of the magnetic field with respect to ab-plane. H _c2 () is estimated from the extracted fourfold component of _c with the flux flow theory. Angular dependence of H _c2 () was well fitted by cos(4). Since the fourfold component of H _c2 () was largest at = n/2, which corresponds to the a-axis direction, the present results strongly suggest the type symmetry in La(Sr)214. In addition, the difference in fourfold component of H _c2 at = n/2 and n/2+/4 was found to increase with decreasing temperature.     

Two-dimensional measurement technique for birefringence vector distributions: data processing and experimental verification

A two-dimensional measurement method for a birefringence vector distribution differs from a point-measurement method not only in the two-dimensional system nonuniformity but also in the system reliability. The previously proposed intrinsic vector allowed for the elimination of the influence of the system nonuniformity, whereas the two-dimensional system reliability is ensured by both an online diagnosis technique and an image lock-in processing. It is revealed that the measured intrinsic vector is relevant not only with the birefringence vector distribution in a sample but also with the natural birefringence vector distributions that exist in the optic components. The complete solution from the measured intrinsic vector results in a bidirectional vector for the desired birefringence vector distribution. The correctness of the two-dimensional measurement principle is examined by means of a comparison of the measured data with that calculated from a finite-element analysis based on the photoelastic effect.     

A novel field‐sequential blue‐phase‐mode AMLCD

Abstract— Through the realization of a blue‐phase‐mode (hereinafter, the operational mode of liquid crystal having a blue phase is referred to as a blue‐phase mode), a display using an improved field‐sequential method was confirmed to be capable of display at a frame rate of 180 fps (field frequency of 540 Hz) or higher. Under this condition, an image without annoyance caused by color breakup was obtained. Moreover, a novel field‐sequential AMLCD integrated with a scan driver by combining the liquid‐crystal‐display (LCD) technology using blue phase and oxide‐semiconductor technology has been developed.     

First-principles multi-electron calculations for L(2,3) ELNES/XANES of 3d transition metal monoxides

A computational method having quantitatively predictive performance of L(2,3) ELNES/XANES of 3d transition metal (TM) compounds without any empirical parameter is given. Calculations are made on three TM monoxides with rock salt structures, MnO, FeO and CoO using model clusters composed of a TM ion with six coordinating oxide ions. Multi-electron wavefunctions are expressed by a linear combination of Slater determinants made by fully relativistic molecular orbitals for TM-2p, 3d and O-2p. Relative intensity and positions of subpeaks are in excellent agreement to experimental spectra. Our analyses of multi-electron eigenstates found that these subpeaks originate not from different one electron configurations but entirely from the multiplet effects. The dependence of the branching ratio on the formal number of 3d electrons agrees with that of an empirical atomic multiplet theory reported in literature.     

Early chick limb cartilaginous elements possess polarizing activity and express hedgehog-related morphogenetic factors

Skeletal patterning and morphogenesis in the developing limb are thought to be regulated by instructive factors and cues from the zone of polarizing activity (ZPA), the apical ectodermal ridge (AER), and the dorsal ectoderm. However, the activities of the ZPA and AER dwindle early in embryogenesis and soon after ceases, when in fact the proximal skeletal elements are still rudimentary in structure and the more distal ones are yet to become recognizable. Thus, we asked whether the chondrocytes emerging within each mesenchymal condensation may themselves start expressing properties similar to those of ZPA and/or AER and, in so doing, may bring skeletal development to completion. Indeed, we found that the cartilaginous, but not precartilaginous, tissues in early chick limbs possess ZPA-like properties. They expressed an endogenous factor related to Sonic hedgehog (Shh), most likely Indian hedgehog (Ihh), and when fragments were grafted to the anterior margin of host stage 16-20 chick wing buds, they induced supernumerary skeletal elements (polarizing activity). The acquisition of polarizing activity by the cartilaginous structures followed clear proximo-to-distal and posterior-to-anterior routes. Thus, (1) stage 25 cartilaginous humerus had polarizing activity while stage 25 prospective radius did not, (2) posteriorly-located stage 29 ulna had stronger activity than anteriorly-located stage 29 radius, and (3) ulna's diaphysis had stronger activity at stage 29 than 31 while radius's diaphysis was stronger at stage 31 than 29. Prior to inducing extra digit formation, the cartilaginous grafts induced Hoxd-12 and Hoxd-13 gene expression in adjacent competent mesenchymal tissue. Strikingly, the cartilaginous grafts activity also expression of Shh and polarizing activity in adjacent mesenchyme, which ZPA grafts cannot do; thus, the cartilaginous structures displayed activities "upstream" of those of the ZPA. The results support our hypothesis that chondrocytes may themselves direct skeletal morphogenesis. In so doing and as a result of their inductive activities, the cells may also have an important role in the completion of limb patterning and morphogenesis.     

Petascale molecular dynamics simulation using the fast multipole method on K computer

In this paper, we report all-atom simulations of molecular crowding — a result from the full node simulation on the “K computer”, which is a 10-PFLOPS supercomputer in Japan. The capability of this machine enables us to perform simulation of crowded cellular environments, which are more realistic compared to conventional MD simulations where proteins are simulated in isolation. Living cells are “crowded” because macromolecules comprise ∼30% of their molecular weight. Recently, the effects of crowded cellular environments on protein stability have been revealed through in-cell NMR spectroscopy. To measure the performance of the “K computer”, we performed all-atom classical molecular dynamics simulations of two systems: target proteins in a solvent, and target proteins in an environment of molecular crowders that mimic the conditions of a living cell. Using the full system, we achieved 4.4 PFLOPS during a 520 million-atom simulation with cutoff of 28 Å. Furthermore, we discuss the performance and scaling of fast multipole methods for molecular dynamics simulations on the “K computer”, as well as comparisons with Ewald summation methods.     

Effect of processing conditions on flash generation

Reduction of flash during injection molding is of great concern for manufacturers of electrical parts. In a previous report, we proposed a theoretical model for flash generation. The present study investigates the effect of processing conditions on flash generation and then attempts to analyze the flash data in terms of the flash model. Specifically, we carry out flow analyses to predict the temperature and pressure of materials when the flash generates. With the thus‐computed parameters, and material properties such as melt viscosity and crystallization temperature, a flash parameter defined in the model is calculated. In the end, it is shown that the flash parameter is correlated with the length of flash generated under various processing conditions. POLYM. ENG. SCI. 45:238–247, 2005. © 2005 Society of Plastics Engineers