Showing papers by "University of Tokyo published in 1979"

Photoelectrocatalytic reduction of carbon dioxide in aqueous suspensions of semiconductor powders

Abstract: WE report here the photoelectrocatalytic reduction of carbon dioxide to form organic compounds such as formic acid, formaldeyde, methyl alcohol and methane, in the presence of photosensitive semiconductor powders suspended in water as catalysts. Photocatalytic reaction kinetics were elucidated by reference to the theory of charge transfer at photoexcited semiconductors.

Path Integral Measure for Gauge Invariant Fermion Theories

Abstract: It is shown that the path-integral measure for gauge-invariant fermion theories is not invariant under the ${\ensuremath{\gamma}}_{5}$ transformation and the Jacobian gives rise to an extra phase factor corresponding to the Adler-Bell-Jackiw anomaly. The derivation of "anomalous" Ward-Takahashi identities by means of the variational derivative can thus be made consistent in the path-integral formalism.

New General Relativity

Abstract: A gravitational theory is formulated on the Weitzenb\"ock space-time, characterized by the vanishing curvature tensor (absolute parallelism) and by the torsion tensor formed of four parallel vector fields. This theory is called new general relativity, since Einstein in 1928 first gave its original form. New general relativity has three parameters ${c}_{1}$, ${c}_{2}$, and $\ensuremath{\lambda}$, besides the Einstein constant $\ensuremath{\kappa}$. In this paper we choose ${c}_{1}=0={c}_{2}$, leaving open $\ensuremath{\lambda}$. We prove, among other things, that (i) a static, spherically symmetric gravitational field is given by the Schwarzschild metric, that (ii) in the weak-field approximation an antisymmetric field of zero mass and zero spin exists, besides gravitons, and that (iii) new general relativity agrees with all the experiments so far carried out.

Zero-and low-field spin relaxation studied by positive muons

Abstract: Zero- and low-field spin-relaxation functions have been studied for the first time by using positive muons, and results are compared with the stochastic theory of low-field relaxation formulated by Kubo and Toyabe. The dipolar broadening of the zero-field relaxation has been studied in detail. In Zr${\mathrm{H}}_{2}$, the zero-field relaxation function of ${\ensuremath{\mu}}^{+}$ has been found to decay ${(5)}^{\mathrm{\textonehalf{}}}$ times faster than the high-field relaxation function, which is explained in terms of the contribution of the nonsecular part of the dipolar interaction. Advantages of the zero-field method over the conventional muon-spin rotation method in practical applications, especially for studies of the ${\ensuremath{\mu}}^{+}$ diffusion/trapping, are discussed.

Spatial Optical Parametric Coupling of Picosecond Light Pulses and Transverse Relaxation Effect in Resonant Media

Abstract: The dynamical properties of a third-order nonlinear optical process, in which two incident light pulses with wave vectors k 1 and k 2 generate a light wave with 2 k 2 - k 1 in resonant media, are discussed with particular attention to the effect of transverse relaxation time T 2 . It is shown that the correlation trace (output light energy vs incident pulse separation) for this process provides a general means of obtaining information on ultrashort T 2 for both the homogeneously and inhomogeneously broadened transitions, and for both t p (pulse width) T 2 . An experimental demonstration for t p > T 2 is given by using a dye molecule and a picosecond light source.

Energy band of photons and low-energy photon diffraction

Abstract: For a model system composed of identical dielectric spheres ordered in a three-dimensional lattice, the secular equation of the energy band of photons is derived and the diffraction of uv or visible light is formulated. The model simulates void lattices in irradiated metals or ordered lattices in polystyrene latexes, in which the large lattice constants and hence the low frequency of the diffracted electromagnetic waves give rise to a Bragg reflection orders of magnitude stronger than that involved in the x-ray diffraction. The present formulation is an extension of the theory of Mie and Debye. Also, it is an extension of the Korringa-Kohn-Rostoker formalism for energy-band calculations to Maxwell's equations or to the vector Helmholtz equation. Although the present paper is restricted to developing a formulation, some characteristic aspects anticipated in low-energy photon diffraction are discussed in relation to low-energy electron diffraction.

Preparation of Colloidal Transition Metals in Polymers by Reduction with Alcohols or Ethers

Abstract: Colloidal dispersions of rhodium, palladium, osmium, iridium, and platinum are prepared by refluxing the methanol-water solutions of rhodium(III) chloride, palladium(II) chloride, osmium(VIII) oxide, sodium chloroiridate, and chloroplatinic acid, respectively, in the presence of poly(vinyl alcohol) as a protective colloid. The preparations of colloidal dispersions of rhodium are successful in the presence of vinyl polymer with polar group such as poly(vinyl alcohol), polyvinylpyrrolidone, or poly(methyl vinyl ether). Polyethyleneimine, gelatin, polyethylene glycol), and dextran are ineffective as the protective colloid. Water-soluble primary alcohols such as methanol and ethanol, water-soluble secondary alcohols such as 2-propanol, and water-soluble diethers such as 1,4-dioxane are available as reductants for preparation of the colloidal dispersion of rhodium. The average diameters of metal particles in the colloidal dispersions of palladium, rhodium, platinum, iridium, and osmium in poly(vinyl a...

Deep Level Transient Spectroscopy of Bulk Traps and Interface States in Si MOS Diodes

Abstract: Deep-leve transient spectroscopy (DLTS) of bulk traps and interface states in Si MOS diodes are theoretically studied and energy levels, capture cross-sections and spatial and energy density distributions of majority-carrier traps are measured. In P+-implanted unannealed MOS diodes, four bulk traps are measured at Ec-0.18 eV, Ec-0.20 eV, Ec-0.31 eV and Ec-0.45 eV. Their spatial distributions are found to be the same among them within experimental error and thought to be corresponding to the distribution of implanted ions qualitatively. Bulk traps are distinguished from interface states experimentally. The capture cross-section of interface states in non-implanted MOS diodes are measured to be of the order of 10-16 cm2 in the energy range of Ec-0.15 eV to Ec-0.30 eV. The interface state density measured with DLTS is found to be in a reasonable agreement with those detetmined by other methods.

The Role of Antigen-Specific T Cell Factors in the Immune Response

Abstract: Publisher Summary This chapter presents a clear account of antigen-specific T cell regulatory factors. The initial concept of interaction of thymus (T)-derived cells and bone marrow (B)-derived cells has been considerably broadened to incorporate macrophage–T cell, T cell–T cell, and T cell–B cell interactions, which as a whole constitute the network of an immunoregulatory system. The interconnectedness of the immunocompetent cells is discussed. The network concept explains it by idiotype–anti-idiotype interactions among lymphocytes. On the other hand, there is abundant experimental data indicating that cell interactions are governed by genes in the major histocompatibility complex (MHC). Several facets of antigen-specific T cell factors found independently by different investigators are examined. There exist both overt similarities and differences between these T bell factors with respect to their immunochemical properties, genetic control, and roles in the immune response.

An Excess Enthalpy Flame Theory

Abstract: A simple idea is proposed to produce an excess enthalpy flame by inserting a porous solid of high thermal conductivity into the one-dimensional flame zone. Heat is recirculated internally through the solid from the downstream high temperature region to the upstream low temperature region and large excess enthalpy is produced at the head of the reaction zone. The potentiality of the proposed artificially modified flame is analyzed on the basis of the simplified one-dimensional flame theory. It is found that in this flame the mass flow rate is not the eigenvalue but becomes a mere parameter. The heat transfer coefficient between the solid and the reacting gas is another parameter. With these additional two parameters the controllability over the flame characteristics increases remarkably. The analysis reveals several attractive characteristics of the flame and that the proposed idea is promising to burn mixtures of low heat content in a simple combustion system.

Single-Site Functional-Integral Approach to Itinerant-Electron Ferromagnetism

Abstract: Itinerant-electron ferromagnetism at finite temperatures is discussed by using the functional-integral method with two fields within the static and saddle-point approximations combined with the single-site approximation; a single atom of a pure metal is regarded as an impurity embedded in the host which is treated by a kind of the alloy-analogy approximation. The amplitude of the local magnetic moment is shown to have a weak temperature dependence and to remain finite even in the paramagnetic state, where the spin susceptibility obeys an approximate Curie-Weiss law. Numerical calculations are made with the use of a simplified model for the density of states of bcc transition metals. Calculated results are discussed with reference to experimental data of iron.

The constituents of Schizandra chinensis Baill. I. Isolation and structure determination of five new lignans, gomisin A, B, C, F and G, and the absolute structure of schizandrin.

Abstract: Five new dibenzocyclooctadiene lignans, named gomisin A (2), B (3), C (4), F (5) and G (6), were isolated from the petroleum ether extract of fruits of Schizandra chinensis BAILL. (Schizandraceae) and their absolute structures were elucidated by chemical and spectral techniques. The absolute structure of schizandrin (1), the plane structure of which had already been elucidated by Kochetkov et al., was also elucidated on the basis of spectroscopic results.

Some problems on the histopathological diagnosis of non-Hodgkin's malignant lymphoma -- a proposal of a new type.

Abstract: A new classification for non-Hodgkin's malignant lymphoma is proposed as the one suited for the Lymphomas in Japan, which is to provide a new subtype "pleomorphic" for those more or less rapid-growing lymphomas of peripheral T-cell nature, along with another subtype lymphoblastic, after Nathwani et al. for those of central T-cell nature. The proposal is based on the result of the investigation by the Study Group for Histopathological Diagnosis on Malignant Lymphoma that (1) the presence of a significant number of T-cell lymphomas with peculiar "pleomorphism" is responsible for the very low reproducibility rate of histopathological diagnosis on the diffuse, mixed L&H type of Rappaport classification, and (2) the relative incidence of lymphoms as peripheral T-cell nature including the so-called adult T-cell leukemia is much higher in Japan than in the Western countries.

Predatory behavior among wild chimpanzees of the mahale mountains

Abstract: Eighteen predatory and two cannibalistic episodes have been observed among wild chimpanzees of the Mahale Mountains. The prey consists mainly of juveniles of medium-sized mammals, six species of which were recorded as prey fauna for the first time in this study. Predatory behavior of Mahale chimpanzees seems more opportunistic and primitive than has ever been observed in the Gombe National Park in terms of capture technique, size of prey, co-operation in hunting, sexual difference in capture frequency, degree of consumption and extent of meat sharing. Cannibalism is an inter-unit-group phenomenon and may be an extension of infanticide, which may function in changing “mother” into “female.”

On Fermat varieties

Abstract: (0.1) x? + x? + + x?+ί = 0 . Throughout this paper, we denote it by Xrm, or by X r m(p), when we need to specify the characteristic p of the base field k; we always assume that m ^ 0 (mod p). The purpose of this paper is to clarify the "inductive structure" of Fermat varieties of a common degree and of various dimensions, and apply it to the questions concerning the unirationality and algebraic cycles of a Fermat variety. The main results are stated as follows: THEOREM I. For any positive integers r and s, XZf is obtained from the product Xrm x X 8 m by 1) blowing up a subvariety isomorphic to X~ x X'*, 2) taking the quotient of the blown up variety with respect to an action of the cyclic group of order m, and 3) blowing down from the quotient two subvarieties isomorphic to P x X'ΰ and Xlr x P\

Formation and Catalytic Functionality of Synthetic Polymer-Noble Metal Colloid

Abstract: Colloidal dispersions of noble metals in synthetic polymers are prepared by reduction with alcohol. Reflux of a solution of rhodium(III) chloride and poly(vinyl alcohol) (PVA) in a methanol-water mixed solvent under argon or air for 4 hr gives a homogeneous solution of colloidal dispersion of rhodium (Rh-PVA-MeOH/H2O). The particle size of metallic rhodium is distributed n a narrow range of 30-70 A, and the average diameter is 40 A. The formation of colloidal rhodium proceeds through three steps: coordination of poly(vinyl alcohol) to rhodium(III) ion, reduction with methanol to form small particles (8 A in diameter), and growth of the small particle to large particle (40 A in diameter). Polyvinylpyrrolidone (PVP) and poly(methyl vinyl ether) (PMVE) can be used in place of poly(vinyl alcohol) and result in colloidal dispersions, respectively, similar to Rh-PVA-MeOH/H2O. Colloidal dispersions in nonaqueous solvent can be prepared by using ethanol instead of methanol-water (Rh-PVP-EtOH) and by usin...

Properties of recirculating turbulent two phase flow in gas bubble columns

Abstract: The equation of motion for the two phase flow within a bubble column, operated within the recirculation flow regime, has been solved, and the profile of liquid flow has been determined. Nicklin's relation for the bubble flow regime has been extended to the recirculation flow regime. Data analysis shows that the mean slip velocity between bubble and liquid is approximately constant and that the kinematic turbulent viscosity increases rapidly with increasing diameter of the column. These observations lead to the conclusion that scale-up has but little influence upon the mean gas holdup.