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Showing papers in "Journal of the Physical Society of Japan in 1957"


Journal ArticleDOI
Ryogo Kubo1
TL;DR: In this paper, a general type of fluctuation-dissipation theorem is discussed to show that the physical quantities such as complex susceptibility of magnetic or electric polarization and complex conductivity for electric conduction are rigorously expressed in terms of timefluctuation of dynamical variables associated with such irreversible processes.
Abstract: A general type of fluctuation-dissipation theorem is discussed to show that the physical quantities such as complex susceptibility of magnetic or electric polarization and complex conductivity for electric conduction are rigorously expressed in terms of time-fluctuation of dynamical variables associated with such irreversible processes. This is a generalization of statistical mechanics which affords exact formulation as the basis of calculation of such irreversible quantities from atomistic theory. The general formalism of this statistical-mechanical theory is examined in detail. The response, relaxation, and correlation functions are defined in quantummechanical way and their relations are investigated. The formalism is illustrated by simple examples of magnetic and conduction problems. Certain sum rules are discussed for these examples. Finally it is pointed out that this theory may be looked as a generalization of the Einstein relation.

7,090 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the piezoelectric effect of bone and found that the maximum value of the PDE was 6×10 -9 c.s.u.
Abstract: The piezoelectric effect of bone has been observed similarly to the case of wood or ramie. The specimens were cut out from the femur of man and ox, and dried completely by heating. The piezoelectric constants were measured by three different experiments, that is, measurements of the static direct effect, the dynamic direct effect and the dynamic converse effect. The piezoelectric effect appears only when the shearing force is applied to the collagen fibres to make them slip past erch other. The magnitude of piezoelectric constant depends on the angle between the applied pressure and the axis of the bone. The maximum value of piezoelectric constant amounts to 6×10 -9 c.g.s. e.s.u., which is about one-tenth of a piezoelectric constant d 11 of quarts crystal. The specimens which were boiled in hot water and afterwards dried completely showed little change in the piezoelectric effect, the fact ascertaining that the effect is not of biological origin. The origin to piezoelectricity in bone may be ascribed to t...

1,272 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examined the possibility to give rigorous expressions for kinetic coefficients such as heat conductivity, diffusion constant, thermoelectric power and so on which relate the flow of a certain kind to the generalized forces of thermal nature.
Abstract: The possibility is examined to give rigorous expressions for kinetic coefficients such as heat conductivity, diffusion constant, thermoelectric power and so on which relate the flow of a certain kind to the generalized forces of thermal nature. We take here as the fundamental assumption Onsager's assumption that the average regression of spontaneous fluctuation of macroscopic variables follows the macroscopic physical laws. The kinetic coefficient G j l appearing in the phenomenological equation, \(\dot{\alpha}_{j}{=}\sum G_{jl}(\partial S/\partial\alpha_{l})\) is shown then to be expressed as \begin{aligned} G_{jl}{=}(k\beta)^{-1}{\int}_{0}^{\infty}d\tau{\int}_{0}^{\beta} d\lambda \end{aligned} where k is the Boltzmann constant and β=1/ k T . This is the same type of formula as we have for kinetic coefficients for mechanical disturbances (Kubo, J. Phys. Soc. 12 (1957) 570). The theory is illustrated for the example of electronic transport phenomena.

557 citations


Journal ArticleDOI
Hide Yoshioka1
TL;DR: The effect of inelastic scattering on electron diffraction by crystals is theoretically studied in this paper, where it is proved that the effect gives rise to an additional complex term to Fourier coefficient of the inner potential.
Abstract: The effect of inelastic scattering on electron diffraction by crystals is theoretically studied. It is proved that the effect of inelastic scattering gives rise to an additional complex term to Fourier coefficient of the inner potential. The imaginary part of the additional term explains qualitatively the observation that two components of a doubly refracted electron beam are subjected to different degrees of absorption (Honjo and Mihama, J. Phys. Soc. Japan 9 (1954) 184). The real part of the additional term gives a correction of about 6∼7 % to the calculated value of mean inner potential at accelerating voltages of 30∼40 kv. This explains the systematic difference between the mean inner potential experimentally obtained by electron diffraction and that calculated by the use of diamagnetic susceptibility (Miyake, Proc. Physico-Math. Soc. Japan 22 (1940) 666).

290 citations


Journal ArticleDOI
TL;DR: In this paper, a set of differential equations for the amplification and absorption of quanta in maser-type amplifiers is presented, and a complete expression for the probability of distribution of the quanta distribution is obtained for the average values and fractional fluctuation.
Abstract: Fluctuations in the amplification and absorption of waves by quantum processes are considered. Assuming for each quantum the probability (per unit time) a of producing another quantum, probability b of being absorbed, and assuming a probability c that a new quantum is introduced, a set of differential equations is obtained. By solving these equations, a complete expression for the probability of distribution of quanta is obtained, as well as expressions for the average values and fractional fluctuation. The expressions developed are applied in particular to maser-type amplifiers, and certain fluctuations in the amplification of electromagnetic waves are pointed out which are important when their quantum character becomes significant. This condition can occur in maser-type amplifiers, where thermal and extraneous noises may be very small. For such an amplifier, a is proportional to the number of excited molecules, whereas b consists of a term proportional to the number of molecules in the ground state plus...

254 citations


Journal ArticleDOI
Kunio Fujiwara1
TL;DR: In this article, it was shown that complete regularity in arrangement is not always necessary but only uniformity is essential for the interpretation of the diffraction patterns of the period of out-of-step of ordered alloys with anti-phase domains.
Abstract: The period of out-of-step of ordered alloys with anti-phase domain structure, measured in atomic distance, is generally not an integer, in spite of sharp splits of superlattice reflections. This fractional property of the period has theoretically been examined. The general treatment of this problem has shown that a regular and uniform arrangement of the different periods of anti-phase domains can explain the fractional value of the period, M . The results of numerical calculations in some models of arrangement have suggested, however, that complete regularity in arrangement is not always necessary but only uniformity is essential for the interpretation of the diffraction patterns.

176 citations


Journal ArticleDOI
TL;DR: In this paper, the magnetic properties of the synthesized solid solution x FeTiO 3 ·(1-x ) Fe 2 O 3 of ilmenite and hematite were investigated in detail for the whole range of 0≦ x ≦ 1.
Abstract: Magnetic properties of the synthesized solid solution x FeTiO 3 ·(1- x ) Fe 2 O 3 of ilmenite (FeTiO 3 ) and hematite (Fe 2 O 3 ) were investigated in detail for the whole range of 0≦ x ≦1. On the experimental side of the study, the most suitable method for preparing the specimen with the largest intensity of magnetization was found. Changes of the Curie point, the estimated intensity of magnetization at 0°K, the Curie constant and the asymptotic paramagnetic Curie point with the composition were presented. It was found that the magnetic properties of the solid solution, x FeTiO 3 ·(1- x )Fe 2 O 3 , could be divided into three parts, (i) x =1, (ii) \(1>x{\gtrsim}0.5\) and (iii) 0.5> x ≧0: Pure ilmenite (FeTiO 3 ) is antiferromagnetic below 55°K and the specimens for \(1>x{\gtrsim}0.5\) are very strongly ferromagnetic and for 0.5> x ≧0 they are again antiferromagnetics on which feeble parasitic ferromagnetism is superimposed. On the theoretical side of the study, these magnetic properties were discussed by...

155 citations


Journal ArticleDOI
TL;DR: In this article, the intensity of the diffuse background from an averaged structure was calculated in the similar way as in the case of binary alloys having short range order, assuming appropriate probability functions for the presence of atoms in different sites.
Abstract: Intensities of X-ray diffraction from α-AgI at various temperatures were measured in the absolute scale by using a G–M counter spectrometer with the crystal monochromated Cu Kα radiation. Measurements of the specific heat and the thermal expansion were also performed. A drastic temperature dependence of the intensities of Debye lines and the presence of a comparatively strong diffuse background were detected. The observed intensities of the Debye lines could be explained well by the disordered structure model (or the “averaged structure”) proposed by Strock (Z. Physik. Chem., B 31 (1936) 132.), assuming fairly large Debye factors for silver and iodine atoms. The intensity of the diffuse background from such an averaged structure was calculated in the similar way as in the case of binary alloys having short range order, assuming appropriate probability functions for the presence of atoms in different sites. It was confirmed that the intensity curves of the diffuse background measured at 250° and 400°C were...

119 citations


Journal ArticleDOI
TL;DR: Growths of α-Fe 2 O 3 whiskers were studied by electron microscopy and diffraction using specimens cut off successively from a uniformly oxidized wire which was heated consecutively to avoid ill effect of contamination condensed during electron-microscopic observation as mentioned in this paper.
Abstract: Growths of α-Fe 2 O 3 whiskers formed on pure iron in oxygen at 400∼850°C were studied by electron microscopy and diffraction using specimens cut off successively from a uniformly oxidized wire which was heated consecutively to avoid ill effect of contamination condensed during electron-microscopic observation. Whisker grows at the tip by surface diffusion of molecules from base to tip. Axial growth at a fixed temperature is approximately given by: l = k t 0.3 , where k , a constant, depends on temperature and has a maximum at 700∼750°C. Initial diameter corresponds to that which gives the minimum strength necessary to keep whisker shape at the growth temperature. A whisker has an axis parallel to hex , becoming thereafter blade-shaped crystal parallel to (001). Further growth at the tip of a blade-shaped crystal occurs at those sites which are in a plane parallel to (001), and similar growth happens on a fracture surface of a mechanically truncated crystal, too.

107 citations


Journal ArticleDOI
TL;DR: In this article, a semi-empirical theory of conjugated double bond systems, including those with non closed-shell structures and heteroatoms, is developed, which is similar with that of Pariser and Parr and that of Pople and others.
Abstract: A general semi-empirical theory of conjugated double bond systems, including those with non closed-shell structures and heteroatoms, is developed The general formulation is similar with that of Pariser and Parr and that of Pople and others, but for non closed-shell structure our equations are somewhat different from those of Pople et al The necessary parameters for hydrocarbons, which have previously been determined arbitrarily as the case may be, are estimated, in the present paper, by using the experimental data of the ethane and ethylene molecules The theory is checked by some simple examples and found to be in satisfactory agreement with experiments

103 citations


Journal ArticleDOI
TL;DR: In this article, it was found that Ni 3 C is formed from metallic nickel with an epitaxial relation (00.1) Ni 3C //(111) Ni and [10.0] Ni 3c //[10\bar1] Ni (Ni 3 C: c.p.h. indices) at the nucleation stage.
Abstract: Thin nickel films formed by evaporation were carburized in CO gas stream at temperatures from 250°C to 500°C and were studied by electron diffraction. Only Ni 3 C was found to be formed. This has c.p.h. arrangement of nickel atoms with lattice constants a h =2.628 A and c h =4.306 A, but showed super-lattice reflections due to a hexagonal lattice of \(a{=}\sqrt{3}a_{h}\) and c =3 c h , which is considered to be caused by a regular arrangement of carbon atoms. The carbide was formed below 450°C in CO gas with slow rate and decomposed rapidly above 430°C in vacuum. The rate of the carbide formation was highest at about 350°C, although it depended very much on the texture of nickel films. Hydrogen atmosphere did not alter essentially the stability of the carbide. It was found that nickel carbide is formed from metallic nickel with an epitaxial relation (00.1) Ni 3 C //(111) Ni and [10.0] Ni 3 C //[10\bar1] Ni (Ni 3 C: c.p.h. indices) at the nucleation stage. A mechanism of the lattice transformation from met...

Journal ArticleDOI
TL;DR: Magnetic susceptibilities and electrical conductivities of (La, Sr)(Fe/Co)O x samples sintered in vacuo or in oxygen stream are measured in this article, showing that tetravalent magnetic ions have Curie contants smaller than those containing only trivalent ions.
Abstract: Magnetic susceptibilities and electrical conductivities of (La, Sr)(Fe/Co)O x samples sintered in vacuo or in oxygen stream are measured here. Samples containing tetravalent magnetic ions in general have Curie contants smaller than those containing only trivalent ions. This fact and the high conductivity in the former specimens strongly support the combined effect of the double exchange and the usual exchange mechanism in these compounds. The parallel alignment of spins of magnetic ions due to double exchange is partly or completely hindered by the presence of the strongly negative trivalent-trivalent interionic interactions.

Journal ArticleDOI
Misazo Yamamoto1
TL;DR: In this paper, a model of weak Gaussian networks is used to study the viscosity behavior of concentrated polymer solution. But the model is restricted to the case where the probability of breakage of a chain in the network is independent of elongation of the chain.
Abstract: Viscosity behaviors of concentrated polymer solution are treated by making use of the model of weak Gaussian network. If chain-breakage coefficient, i.e. the probability of breakage of a chain in the network is independent of elongation of the chain, such system shows the Newtonian flow. Proper choice of chain-breakage coefficient, for example, that of square well type, yields a typical rate dependence of viscosity; the larger the rate of shearing flow, λ, the smaller the value of viscosity coefficient, µ. The tensile viscosity, µ * , is also considered, which in general increases with the rate of stretching, λ * , for small values of the rate. The so-called Trouton's formula, µ * =3µ is satisfied only in the limit of zero values of rates λ and λ * .

Journal ArticleDOI
TL;DR: The lattice energies of the 20 binary compounds composed of Be ++ Mg ++, Ca ++, Sr ++, Ba ++, O -, S -, Se - and Te - have been computed by previously well-tested procedures as mentioned in this paper.
Abstract: The lattice energies of the 20 binary compounds composed of Be ++ Mg ++ , Ca ++ , Sr ++ , Ba ++ , O - , S - , Se - and Te - have been computed by previously well-tested procedures. Because of lack of sufficiently reliable compressibility data, the computations have been made with two different assumptions regarding the magnitude of the constant a in the exponent of the repulsion energy term. These two assumptions yield lattice energies which differ, in most cases, by about 20 kcal. In general, a single value of the “constant energy radius” suffices for each type of ion. For the beryllium compounds, however, it was necessary to use different radii for the Be ++ ion for each compound. In MgTe also, a slightly different Mg ++ radius from that deduced for the other magnesium compounds was required. These irregularities may be related to the fact that these crystals have “tetrahedral” structures, unlike the others, with significant but unknown amounts of covalent bonding. The characteristic constants deduced s...

Journal ArticleDOI
TL;DR: In this paper, the cluster variation method of approximation for the cooperative phenomena in the lattice system is generalized so as to be applicable to the cases where the range of the interaction is long compared to the distance of neighboring (lattice) points.
Abstract: The cluster variation method of approximation for the cooperative phenomena in the lattice system is generalized so as to be applicable to the cases where the range of the interaction is long compared to the distance of neighboring (lattice) points.

Journal ArticleDOI
TL;DR: In this paper, the microwave spectrum of normal methyl mercaptan has been studied in the frequency range from 14 to 29 kMc/sec and the potential barrier height hindering internal rotation has been determined as 444±10 cm -1 from the analysis of the lines corresponding to the transitions involving both over-all and internal rotations.
Abstract: The microwave spectrum of normal methyl mercaptan has been studied in the frequency range from 14 to 29 kMc/sec. The potential barrier height hindering internal rotation has been determined as 444±10 cm -1 from the analysis of the lines corresponding to the transitions involving both over-all and internal rotations. The fine structures of J =1←0, K =0←0 lines of the various isotopic species have also been analysed and discussed. The molecular structure of methyl mercaptan has been calculated to be d SH =1.336±0.01 A, d CS =1.819±0.005 A, d C H =1.091±0.01 A, \(\angle\)CSH=96°30'±1°, \(\angle\)HCH=109°45'±30' and the angle between CS bond and methyl axis, θ=2^°0'±30'.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the magnetic anisotropy induced by mechanical rolling of ferromagnetic alloys and found that the maximum value of uniaxial anisotropic was 2∼3×10 5 erg/cc.
Abstract: Investigation was made on the magnetic anisotropy induced by mechanical rolling of ferromagnetic alloys. Experiments were carried out on the single crystals of Ni 3 Fe through observation of magnetic domain patterns and torque measurements. Easy magnetizing direction was found to be normal to the roll direction for (110) [001] and (001) [100] rolling, while it changes to parallel to roll direction at about 30% reduction for (001) [110] rolling. The maximum value of uniaxial anisotropy was 2∼3×10 5 erg/cc. The results were satisfactorily explained by assuming the appearance of directional order by slip deformation. It was shown theoretically that the anisotropies thus induced are classified into long range order (fine slip) type and short range order (coarse slip) type. Relation to the superlattice formation was also discussed.

Journal ArticleDOI
TL;DR: In this paper, the problem of the convergence of the absorption wavelengths of chain conjugated systems, polyenes, and merocyanines, is discussed, by using the method developed in the previous paper.
Abstract: The problem of the convergence of the absorption wave-lengths of chain conjugated systems, polyenes, and merocyanines, is discussed, by using the method developed in the previous paper. It is shown that the bond alternation as the cause of the convergence of the absorption wave-lengths, which has been presumed from the view of the resonance theory but cannot be deduced in terms of the ordinary molecular orbital theory, do actually occurs even for an infinite polyene chain, but the calculated limiting wavelength does not agree with the experiment quantitatively, possibly because of the coulomb attraction between the excited electron and the hole.

Journal ArticleDOI
TL;DR: In this article, exact solutions of the Navier-Stokes equations are obtained for the boundary layer growth on an infinite flat plate with uniform suction or injection (with velocity V normal to its plane) which is started at time t = 0, with velocity U along its plane.
Abstract: Exact solutions of the Navier-Stokes equations are obtained for the boundary layer growth on an infinite flat plate with uniform suction or injection (with velocity V normal to its plane) which is started at time t =0 (with velocity U along its plane), for the two cases: i) U =arbitrary, V =const and ii) U ∞ t α , V ∞ t -1/2 . i) gives simple relations between the cases of suction and injection and ii) gives similar velocity profiles. Rayleigh's problem ( U =const) is investigated in detail, and the resulting solutions show the same qualitative natures as the corresponding steady flow solutions for an semi-infinite flat plate so far obtained.

Journal ArticleDOI
TL;DR: In this paper, a series of papers on the internal motion and the structure of methyl amine have been published, including the analysis of the barrier height of internal rotation of CH 3 MH n type molecules.
Abstract: This is the final report of a series of papers from this laboratory on the internal motion and the structure of methyl amine. Most of the observed lines including J =1←0, K =0←0 lines were analyzed in the frequency range between 4 and 50 kMc/sec. The barrier height of internal rotation has been determined to be 691.1 cm -1 as well as the molecular structure, d CN =1.474 A, \(\angle\)HNC=112°10', \(\angle\)HNH=105°50', \(\angle\)HCH=109°30' and the angle between CN and methyl axis=3°30' on the assumption that d CH =1.093 A and d NH =1.014 A. These results were compared with the barrier height and the structure of other CH 3 MH n type molecules, methyl alcohol and methyl mercaptan. The inversion doubling of the observed lines was also analyzed satisfactorily. The quadrupole coupling constant of N 14 along the charge symmetry axis has been obtained as -3.6±0.3 Mc/sec, with the direction of the axis, 90°±8, from the methyl axis.

Journal ArticleDOI
TL;DR: In this article, a group-theoretical treatment of the spatial symmetry at certain special values of the wave vector K was applied to a study of electronic energy bands in metal borides MeB 6.
Abstract: The tight-binding approximation is applied to a study of electronic energy bands in metal borides MeB 6 . The 25×25 determinantal secular equation for the energy is reduced by a group-theoretical treatment of the spatial symmetry at certain special values of the wave vector K . The results are that if metal atoms have two valence electrons the valence bands are all filled and the conduction bands are all empty, and in the case of calcium boride CaB 6 the narrowest gap between valence-and conduction-bands is at edges of the first Brillouin zone, the simple cube in the reciprocal space and its width is about 1.5 eV, in good agreement with empirical results that there exist only borides of elements having two valence s electrons in this type of structure.

Journal ArticleDOI
TL;DR: Based on LCAO MO CI method, the wave functions of Li 2 in the ground state 1 Σ g + and three lower excited states 3 Σ u +, 1 ǫ u+, and 1 Π u are calculated non-empirically.
Abstract: Based on LCAO MO CI method, the wave functions of Li 2 in the ground state 1 Σ g + and three lower excited states 3 Σ u + , 1 Σ u + , and 1 Π u are calculated non-empirically. Calculation is performed at internuclear distances of 4.5, 5.0 and 5.5 a.u. by use of 1 s , 2 s , and 2 p atomic orbitals of Stater type. Further, for the ground state, various approximations are investigated. Among other results, it is to be noted that HL method gives a lower total energy than MO method, and that in CI wave function a configuration corresponding to π-bond appears with an unexpectedly large coefficient. By using these wave functions depth of adiabatic potentials, dissociation energy, and vertical excitation energies are calculated and compared with the observed values. Further, molecular quadrupole moment, gradient of the electric field at each nucleus, and oscillator strengths are calculated. It is found that, in general, CI improves appreciably the values of these quantities calculated by the single configuration....

Journal ArticleDOI
TL;DR: In this article, the dipole interaction term has been obtained approximately from the difference of the energy of ferroelectric and antiferroelectric (stripes type) dipole configurations.
Abstract: The energy of the 180°-type domain wall of BaTiO 3 crystal is obtained as 1.4 erg/cm 2 considering the dipole interaction and other interatomic energy of Born type. The dipole interaction term has been obtained approximately from the difference of the energy of ferroelectric and antiferroelectric (stripes type) dipole configurations. The wall is found to be quite thin, that is, the change of polarization at the boundary is abrupt, in contrast with the ferromagnetic walls. The structure of the 180° domains and their reversing process are also discussed.

Journal ArticleDOI
TL;DR: In this paper, the problem of diffraction of plane electromagnetic waves by an infinitely thin, perfectly conducting infinitely long ribbon and by an infinite long slit in a plane conducting screen, where the plane of incidence is perpendicular to the edge of the ribbon or slit but arbitrary angle of incidence and polarization, was solved by the method of expansion in the hypergeometric polynomial.
Abstract: Rigorous solutions are presented of the problem of diffraction of plane electromagnetic waves by an infinitely thin, perfectly conducting infinitely long ribbon and by an infinitely long slit in a plane conducting screen, where the plane of incidence is perpendicular to the edge of the ribbon or slit but arbitrary angle of incidence and polarization. The unique solution satisfying the edge condition is obtained from the electric and magnetic type Hertz vectors, each of which has one scalar component, by the method of expansion in the hypergeometric polynomial. The expressions of the scattering coefficient, transmission coefficient, electric current on the ribbon, electric field in the slit, electric field at the distant place are obtained as a function of k a =2π a /λ.

Journal ArticleDOI
TL;DR: In this paper, large single crystals of Fe 7 Se 8 and Fe 3 Se 4 were prepared, and their magnetic properties below the Curie point were investigated by a torque magneto meter.
Abstract: Large single crystals of Fe 7 Se 8 and Fe 3 Se 4 were prepared, and their magnetic properties below the Curie point were investigated by a torque magneto meter. The results obtained on Fe 7 Se 8 at room temperature show similar characterics to that of natural pyrhotite (Fe 7 S 8 ), i.e. the crystals can be magnetized only in the c -plane. As the temperature is lowered, however, the c -axis becomes the direction of easy magnetization. This change in direction seems to occur gradually. In the case of Fe 3 Se 4 , such a change in direction of easy magnetization does not take place. The obtained saturation magnetizations for Fe 7 Se 8 and Fe 3 Se 4 are respectively 68 and 80 gauss at the liquid air temperature.

Journal ArticleDOI
TL;DR: In this paper, a solution of the Stokes equations of motion of a viscous fluid is given in a form suitable for dealing with the flows past an ellipsoid, and the solution is expressed in infinite triple integrals.
Abstract: A solution of the Stokes equations of motion of a viscous fluid is given in a form suitable for dealing with the flows past an ellipsoid. When the ellipsoid has rotational symmetry, the solution is expressed in infinite triple integrals. By utilizing these results, two kinds of steady flows of a viscous fluid past a spheroid are studied when the direction of the main stream is parallel to the axis of symmetry of the spheroid. The first is the flow past a spheroid between two parallel plane walls and the second is the flow past a spheroid in a cylindrical pipe with its axis of revolution along the axis of the pipe. In particular, the drag and the moment acting on the spheroid as well as the pressure drop in the pipe are discussed in detail. It is worth noticing that the moment of force acting on a spheroid moving uniformly between two parallel walls changes its sign when the rate of roundness of the spheroid exceeds a certain definite value.

Journal ArticleDOI
TL;DR: In this paper, the exact number of activated nuclei in samples was determined by measuring the beta-rays from the samples with a 4π-proportional counter and applying the method of extrapolation.
Abstract: The nuclear reactions of Al, Fe, Cu, Zn, Mo and Ag produced by the neutrons from the T 3 ( d , n ) He 4 reaction have been investigated by means of the activation technique. The absolute numbers of activated nuclei in samples were determined by measuring the beta-rays from the samples with a 4π-proportional counter and applying the “ method of extrapolation.” By utilizing the variations of neutron energies in the laboratory system, an excitation curve of Mo 92 ( n , 2 n )Mo 91 reaction was obtained. For the cases of Al, Cl, Zn and Ag, only the gradients of excitation curves were also found. The experimental cross sections were determined as follows: 87.2 mb±8% for Al 27 ( n , p )Mg 27 , 120 mb±12% for Al 27 ( n , α)Na 24 , 144 mb±13% for Fe 56 ( n , p )Mn 56 , 556 mb±5% for Cu 63 ( u , 2 n )Cu 62 , 119 mb±12% for Zn 64 ( n , 2 n )Zn 63 , 60.2 mb±12% for Zn 66 ( n , p )Cu 66 , 132 mb±16% for Mo 92 ( n , 2 n )Mo 91 , 458 mb±11% for Ag 107 ( n , 2 n )Ag 106 , and 604 mb±11% for Ag 109 ( n , 2 n )Ag 108 . Com...

Journal ArticleDOI
TL;DR: In this paper, the authors measured the line width and spin-lattice relaxation time of hexamethyldisilane at different temperature ranges from liquid air to room temperature and found that even at liquid air temperature, each CH 3 group reorientates about its threefold symmetry axis so rapidly as to narrow the dipolar width due to three proton interactions within itself (activation energy 2.6 kcal/mole).
Abstract: Proton magnetic resonance of solid hexamethyldisilane was studied. Line width and spin-lattice relaxation time were measured in temperature range from liquid air to room temperature. By analysing these quantities following results were obtained: Even at liquid air temperature, each CH 3 group reorientates about its three-fold symmetry axis so rapidly as to narrow the dipolar width due to three proton interactions within itself (activation energy 2.6 kcal/mole). Then at about -120°C, reorientation of CH 3 -groups about the axis joining two silicon atoms becomes rapid enough to narrow the width further (activation energy 5.7 kcal/mole). Spin-lattice relaxation time varies qualitatively in accordance with the above considered reorientational motions. At -51.3°C, this crystal changes its structure and at the same time rapid reorientational motion of the molecular axis is excited, resulting discontinuous decrease in the line width and discontinuous increase in the spin-lattice relaxation time. Above the transi...

Journal ArticleDOI
TL;DR: In this article, the structures of the ordered copper-palladium alloys in the composition range from 15.5 to 28.5 atomic per cent Pd were investigated by X-ray diffraction, using both single crystals and power specimens.
Abstract: The structures of the ordered copper-palladium alloys in the composition range from 15.5 to 28.5 atomic per cent Pd were investigated by X-ray diffraction, using both single crystals and power specimens. The alloys with the composition of 20.8 to 25.8 atomic per cent Pd have an anti-phase domain structure in a fully ordered state cooled slowly from 450°C to room temperature in four months. This structure is formed from the elementary face-centered tetragonal lattice, in which the atoms arrange themselves as in the ordered alloy Cu 3 Au but step-shifts occur at a definite period along the tetragonal axis. On the other hand, the alloys of 27.3 and 28.5 atomic per cent Pd were confirmed to possess a more complicated anti-phase domain structure characterized by the two kinds of out-of-step, which was already elucidated by the electron diffraction study in Part I. Variation of both the lattice parameters and the periods of anti-phase domain with composition were also studied.

Journal ArticleDOI
TL;DR: In this paper, a condenser microphone was used as a transducer with a ratio discriminator to measure the intensity of static pressure fluctuation as well as the correlation between pressure and velocity fluctuation.
Abstract: With a view to observing pressure fluctuations in turbulent flow of fluid, a new apparatus was constructed by using a condenser microphone as a transducer with a ratio-discriminator. The frequency response of the apparatus was calibrated by means of Karman vortices produced by a circular cylinder. The Helmholtz resonance and the loss in the pressure duct were compensated electrically by a band-rejection filter and a high-frequency booster. By these devices, the overall frequency response of the pressure-measuring apparatus was made flat between 50 and 1500 cycles per second. Using the apparatus in combination with a single rotary type hot-wire anemometer, it proved succesful in determining the intensity of static pressure fluctuation as well as the correlation between pressure and velocity fluctuation. Consequently all the terms in the energy equation became measurable, and the energy equation for the fluctuating quantities was ascertained experimentally for the first time in the wake of a circular cylind...