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Showing papers by "Tokyo Institute of Technology published in 1980"



Journal ArticleDOI
TL;DR: In this article, the longitudinal elastic strain was measured for electric fields applied along the 〈100〉 direction in single crystals of lead magnesium niobate [Pb(Mg1/3Nb2/3)03], using a bonded strain gauge technique.
Abstract: Transverse and longitudinal elastic strain have been measured for electric fields applied along the 〈100〉 direction in single crystals of lead magnesium niobate [Pb(Mg1/3Nb2/3)03], using a bonded strain gauge technique. A quadratic electrostrictive relation holds between induced elastic strain and electric polarization for temperatures near the low‐frequency dielectric maximum. The electrostriction coefficients are almost temperature independent with values Q11=2.50×10−2 m4/C2 and Q12=−0.96×10−2 m4/C2. To check the direct measurements, the hydrostatic Q coefficient was determined independently by measuring the pressure dependence of the dielectric permittivity. The value Qh =0.60×10−2 m4/C2 obtained is in good agreement with that calculated from the direct measurements.

328 citations


Journal ArticleDOI
TL;DR: In this paper, the Pb3MgNb2O9-PbTiO3 family of relaxor ferroelectrics are proposed for use as active elements in adaptive optic systems and similar applications.
Abstract: Lead magnesium niobate and other relaxor ferroelectrics are promising transducer materials for use as active elements in adaptive optic systems and similar applications. These ceramics are dominantly in the paraelectric phase, and dimension control is obtained through the high intrinsic quadratic electrostrictive effect. Since stable ferroelectric domain structures do not occur, the problems of dimensional creep and non-reproducibility (aging and de-aging effects) of the conventional poled piezoelectric ceramic are largely eliminated. Suitably chosen compositions in the Pb3MgNb2O9-PbTiO3 family give electrostriction strains ten times larger than those of conventional BaTiO3-based ceramics. Low expansion coefficients are an added advantage for thermal stability.

283 citations


Journal ArticleDOI
TL;DR: In this article, the structural details of doped polyacetylene (a highly conducting organic polymer) were studied using optical absorption, Raman, and infrared spectra of polyacetylenes.
Abstract: In order to elucidate the structural details of doped polyacetylene (a highly conducting organic polymer), the optical absorption, Raman, and infrared spectra of not only trans‐(CH)x doped with iodine, AsF5, and SO3 but also β‐carotene doped with iodine and SO3 were studied. The infrared spectra of two kinds of isotopically substituted polyacetylenes (CD)x and (13CH)x doped with iodine were also observed. Analysis of the experimental results shows that upon doping each of the four vibrational branches (ν1–ν4) in the 1600–900 cm−1 region of a polyene chain splits into two groups, namely, the higher frequency group and the lower frequency one. The former group consists of the ’’gerade’’ vibrations of polyene parts which are not directly attacked by dopants but are perturbed along the chain, whereas the latter is made up of the ’’ungerade’’ vibrations of the positively charged polyene part with the doped site at its center. The Raman bands in the higher‐frequency group of ν1 (mainly the C=C stretching mode) ...

278 citations


Journal ArticleDOI
TL;DR: In this paper, the path independent integral, J, is presented as the rate of energy flux during crack extension, which is an extension of the J-integral proposed by Rice and includes the existence of a fracture process region and the effect of plastic deformations, body forces, thermal strains and inertial of material.

258 citations


Journal ArticleDOI
TL;DR: In this paper, the temperature dependence of the differential quantum efficiency ηd and threshold current density Jth of 1.6 µm In1-xGaxAsyP1y lasers is investigated.
Abstract: Measurements are presented of the temperature dependence of the differential quantum efficiency ηd and threshold current density Jth of 1.6 µm In1-xGaxAsyP1-y lasers. The observed sharp decrease in ηd near room temperature is interpreted as due to absorption associated with transitions of electrons from the split-off valence band into holes injected into and thermally generated within the heavy hole valence band. Preliminary calculations using conventional laser theory predict a temperature variation corresponding to T0145 K. This together with the influence of ηd, appears to be sufficient to explain most of the observed temperature variation of Jth.

210 citations


Journal ArticleDOI
TL;DR: Reflection electron microscopy in ultra high vacuum has been performed during the process of thermal cleaning which converts the dirty (111) silicon surface of the 1 × 1 structure to the clean surface of 7 × 7 structure, and during the transformations of the 7 ×7 structure to 5 × 1, √ 3 × √3 and 6 × 6 structures produced by deposition of gold up to a few monatomic layers as discussed by the authors.

199 citations



Journal ArticleDOI
TL;DR: In this article, various allylic esters of acetoacetic acid undergo rearrangement to give γ, δ-unsaturated methyl ketones in high yields with elimination of carbon dioxide under mild conditions in the presence of catalytic amounts of Pd(OAc) 2 and PPh 3.

187 citations


Journal ArticleDOI
TL;DR: In this paper, a new type of cathode sputtering apparatus with two targets facing each other was developed to prepare magnetic films at a high deposition rate without the extreme rise of the substrate temperature.
Abstract: A new type of cathode sputtering apparatus with two targets facing each other has been developed to prepare magnetic films at a high deposition rate without the extreme rise of the substrate temperature. When two disks of iron and nickel were used as targets, the maximum deposition rates obtained were approximately 4000 and 5000 A/min, respectively. The substrate temperature was not elevated above 200°C during sputtering. The high rate deposition of Mo permalloy films also was attempted by co-sputtering of two facing targets composed of disks of iron and nickel and chips of molybdenum. The Vicker's hardness of the obtained Mo permalloy films was about 900 and the typical values of permeability at 1 MHz magnetic field and coercive force at dc magnetic field of them were about 2500 and 0.16 Oe, respectively.

159 citations


Journal ArticleDOI
10 Oct 1980-Science
TL;DR: The hydrogen concentration in soil gas has been measured in the area around the Yamasaki Fault, one of the active faults in southwestern Japan, and a hypothesis on the production of hydrogen by fault movements is postulated.
Abstract: The hydrogen concentration in soil gas has been measured in the area around the Yamasaki Fault, one of the active faults in southwestern Japan. Degassing of a significant amount of hydrogen (up to more than 3 percent by volume) has been observed for sites along the fault zone. The hydrogen concentration in soil gas at sites away from the fault zone was about 0.5 part per million, almost the same as that found in the atmosphere. The spatial distribution of sites with high hydrogen concentrations is quite systematic. A hypothesis on the production of hydrogen by fault movements is postulated.

Journal ArticleDOI
TL;DR: In this paper, a modified model based on the thermally activated model proposed by Liang and Pope was used to derive the activation constants of a 3-subgroup element minority component in A3B alloys and showed that the lower phase stability of the Ll2 phase with respect o the DO22 phase is responsible for the anomalous strength behavior.
Abstract: The positive temperature dependence of strength was confirmed by means of compression tests in Ll2 ordered alloys which had been newly added to the group of those exhibiting a positive strength behavior in hot hardness tests in previous work. Those were Pt3In, Pt3Sn, Pd3Pb, Fe3Ga, Pt3Ti, Pt3Cr, Pd4Ti, and Zr3In. Moreover, Pt3Al, Pt3Ga and Pt4Sb were added to the group of anomalous compouds in this study. The activation constants were derived from a modified model based on the thermally activated model proposed by Liang and Pope. From the relationships among the derived activation constant, the apparent atomic radius ratio and the electron concentration for platinum-and nickel-based alloys, it was deduced that the Ll2 phase tends to be destabilized with respect o the DO22 phase before the DO19 phase becomes stable as the relative atomic radius of the B-subgroup element minority component in A3B alloys is increased. Itwas also shown that 4B-subgroup elements make the Ll2 phase of A3B alloys less table than 3B-subgroup elements as one of the components. It was confirmed that the lower phase stability of the Ll2 phase with respect o the DO22 phase is responsible for the anomalous strength behavior. This conclusion is consistent with the thermally activated cross slip model. From this result it was proposed that a systematic variation in phase stability can be achieved by the partial replacemextt ofone of the elements in an alloy in either direction, according to whether the atomic radius or electron concentration is to be increased or decreased. (Received December 27, 1979)

Journal ArticleDOI
TL;DR: The macroscopic morphology of as-prepared polyacetylene depends on the concentration of the catalyst system, and the average fibril diameter of 200 A may depend on the polymerization conditions.

Journal ArticleDOI
TL;DR: In this paper, a copper electrode in a chloride medium with or without benzotriazole (BTA) was made over a wide frequency range (10 −2 −10 2 KHz).

Journal ArticleDOI
TL;DR: In this article, measurements were made of the dielectric constant along the ferroelectric axis e a, the spontaneous polarization P s and the heat capacity c p of Rb 2 ZnCl 4 crystals in the temperature range from -150^° C to 150°C.
Abstract: Measurements were made of the dielectric constant along the ferroelectric axis e a , the spontaneous polarization P s and the heat capacity c p of Rb 2 ZnCl 4 crystals in the temperature range from -150^° C to 150°C. The normal-incommensurate transition point determined as the peak position of c p lies at 30.1°C, which is about 6°C lower than the temperature for the maximum of e a . It was found that e a and P s show a characteristic thermal hysteresis over a wide temperature range including the incommensurate-commensurate trarasition point (-80^° C ). The thermal hysteresis occurs even when heating and cooling runs are cycled within the incommensurate phase. The observed thermal hysteresis is understood if we assume that defects such as impurities act as obtacles to diffusion of discommensurations and prevent the crystal from reaching thermal equilibrium.

Journal ArticleDOI
TL;DR: For a given model graph and pattern on it, the cause of state changes and the manner of their propagation are easily found out by the present approach, which is mainly based on the depth-first search algorithm developed by Tarjan.

Journal ArticleDOI
TL;DR: This enzyme may be related to the regulation of substance P in the brain, and to the development of neurones by forming the tetrapptide because the tetrapeptide has almost the same effect as substance P on the neurite extension of neuroblastoma.
Abstract: We determined changes in prolyl endopeptidase activity in developing rat brain. A new and highly sensitive fluorogenic substrate, 7-(succinyl-Gly-Pro)-4-methylcoumarinamide, was used for determination of the enzyme activity. The enzyme activity per brain increased until 2 weeks of age, and then decreased during maturation. The enzyme was purified about 7800-fold from the brain of the rat at 2 or 3 weeks of age. The enzyme has a pH optimum of 5.8 to 6.5, and an approximate molecular weight of 70,000. The enzyme activity was completely inhibited by low concentrations of diisopropylfluorophosphate and partially inhibited by high concentrations of phenylmethanesul-phonylfluoride, which are potent serine protease inhibitors. Moreover, thiolblocking agents and some heavy metals also have a strong effect on the activity. Bacitracin was found to be a potent inhibitor, with an IC50 value of 2.5 × 10−6m at 0.5 mm of the substrate. The enzyme was proved to hydrolyze the NH2-terminal tetrapeptide, Arg1-Pro2-Lys3-Pro4, from substance P to produce the heptapeptide, Gln5-Gln6-Phe7-Phe8-Gly9-Leu10-Met11-CONH2. The Km value of the hydrolysis of substance P was 1.0 mm. This enzyme may be related to the regulation of substance P in the brain, and to the development of neurones by forming the tetrapeptide because the tetrapeptide has almost the same effect as substance P on the neurite extension of neuroblastoma.

Journal ArticleDOI
TL;DR: In this article, a digital control system to control a double inverted pendulum on a cart is presented, where the cart is placed on an inclined rail and is to be kept in position at a given reference point.
Abstract: A digital control system to control a double inverted pendulum on a cart is presented, where the cart is placed on an inclined rail and is to be kept in position at a given reference point. The controller design is based on linear servo control theory and can control the cart position of the inverted pendulum, eliminating the effect of the rail incline. Theoretical analyses of the pendulum and of the control system are given.

Journal ArticleDOI
TL;DR: In this article, terminal acetylenes were converted to acetylenecarboxylates in high yields under atmospheric pressure of carbon monoxide at room temperature using a catalytic amount of PdCl 2 and a stoichiometric amount of CuCl 2.

Journal ArticleDOI
TL;DR: In this article, the electrostrictive coefficients of Pb(Mg1/3Nb2/3)O3 ceramics have been precisely determined over a wide temperature range from -110°C to 100°C, using three different methods: strain gauge, piezoelectric resonance and interferometric techniques.
Abstract: The electrostrictive coefficients Q33 and Q13 of Pb(Mg1/3Nb2/3)O3 ceramics have been precisely determined over a wide temperature range from -110°C to 100°C, using three different methods: strain gauge, piezoelectric resonance and interferometric techniques. A quadratic relation between induced strain and electric polarization holds even in the ferroelectric phase, as well as in the paraelectric phase. The electrostrictive coefficients are nearly temperature-independent with values of Q33=2.3(±0.2)×10-2 m4C-2 and Q13=-0.64(±0.05)×10-2 m4C-2. The field-induced piezoelectric coefficients d33 and d31 were also measured at room temperature as a function of dc bias field. The values of d33/e3 and d31/e3 are proportional to the induced electric polarization. The electrostrictive coefficients calculated from the slopes are in good agreement with those obtained by the strain-gauge method.

Journal ArticleDOI
TL;DR: In this paper, the precice variational formulas without error terms were obtained for ω(x, y) the fundamental normalized Abelian differentials of the second kind (Theorems 4 and 6), from which one may deduce similar formulas for any Abelian differential and period matrices in the usual way.
Abstract: In the present paper, we shall study two basic types of degenerations of compact Riemann surfaces considered by Schiffer-Spencer [10] and Fay [3]. According to the simple formalism of the degeneration considered here, the precice variational formulas without error terms will be obtained for ω(x, y) the fundamental normalized Abelian differentials of the second kind (Theorems 4 and 6), from which one may deduce similar formulas for any Abelian differentials and period matrices in the usual way. It turns out, however, that all the variational formulas found in the book by Fay [3] disagree with ours and it seems to us that they are incorrect, which is, to some extent, seen from the examples in the last section of this paper. In our formulas the coefficients βjk of an expansion of ω(x, y) plays an important role. In this connection a variant of Golusin's inequality will be obtained for βjk's (Theorem 5) which can be viewed as the generalized Faber coefficients. Our method is completely elementary (c.f. Fay [3]) and yields some extension of the results in [3] and [6].

Journal ArticleDOI
TL;DR: In this article, the dispersion spectra of the following liquids were measured in the absence of solvent and the results were reported as the real and imaginary components of the complex refractive index (n, k).
Abstract: The infrared absorption spectra and corresponding dispersion spectra of the following liquids have been measured over the range 4200 to 250 cm−1: cyclo-C5H10, CH3•NO2, CH3•CN, CH2Br2, CH2Cl2, CBrCl3, CCl4, C6H6, C6H5•CH3, C6H5Cl, C6H5Br, C6H5I, and C6F6. The spectra were measured in the absence of solvent and the results are reported as the real and imaginary components of the complex refractive index (n, k). The experimental technique combines transmission measurements through thin films and attenuated total reflection measurements by a method which has been described previously. The complete spectral and dispersion curves are displayed graphically; the absorption maxima are tabulated as absorption indices (kmax) and as molar absorption coefficients (emax). The dispersion extrema (nmin, nmax) are also listed and the experimental uncertainties in these quantities are evaluated. Provision is made to supply the complete optical constant data on magnetic tape at encoded intervals of 0.5 cm−1.

Journal ArticleDOI
TL;DR: In this article, a formula is derived for determining the stress intensity factors from the path independent J-integral which has been formulated in the previous paper as the energy release rate by taking the effect of inertia into account.

Journal ArticleDOI
TL;DR: The pseudobinary equilibrium phase diagram Ni3Ge-Fe3Ge has been established by metallographic study to confirm the existence of a continuous solid solution of the L12 structure between Ni3 Ge and γ′Fe3 Ge as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, the Dieckmann condensation of this diester using potassium hydride afforded 2-ethoxycarbonylcyclo-9-heptadecenone, which was converted by hydrolysis and decarboxylation to cyclo 9-hexadecene (civetone) as a mixture of cis and trans isomers in 54% yield.

Journal ArticleDOI
TL;DR: In this paper, the GaInAsP/InP integrated twin-guide laser with first-order distributed Bragg reflectors (DBR-ITG) was fabricated and operated at room-temperature with a single longitudinal mode.
Abstract: GaInAsP/InP integrated twin-guide lasers with first-order distributed Bragg reflectors (DBR-ITG lasers) were fabricated and operated at room-temperature with a single longitudinal mode. By changing the corrugation period, the central wavelength could be varied in the wavelength range of 1.2~1.3 µm with a single longitudinal mode at temperatures between 150 and 300 K. At room-temperature, the threshold current density and the differential quantum efficiency were 10.4 kA/cm2 and 11.7%, respectively. The refractive index of the quaternary composition was measured and found to be in relatively good agreement with the estimated value. "GaInAsP/InP Integrated Twin-Guide Lasers with First-Order Distributed Bragg Reflectors at 1.3 µm Wavelength"

Journal ArticleDOI
TL;DR: In this article, a simple expression for the dynamic stress intensity factor of a pre-cracked Charpy specimen is derived by making use of an approximate solution for one-dimensional beam equations.

Journal ArticleDOI
TL;DR: It is suppose that post-propline cleaving enzyme activity in the brain is similar, if not identical, to that in the kidney.
Abstract: We have studied the distribution of post-propline cleaving enzyme activity in the various tissues in humans using 7-(succinyl-Gly-Pro)-4-methylcoumarinamide as substrate. The post-propline cleaving enzyme activity was high in muscle, testes, kidney and submandibular gland, but was low in the heart, mesenterium and aorta. In the brain, relatively high post-propline cleaving enzyme activity was observed in the cerebral cortex, but other brain regions showed a very low enzyme activity. On Sephadex G-100 column chromatography, enzyme activity in human kidney showed a major peak and a minor peak. The major peak coincided with the enzyme in human cerebral cortex, but was different from human serum enzyme. Diisopropylfluorophosphate, a serine protease inhibitor, strongly inhibited the enzyme activity of each active fraction. The enzyme in the cerebral cortex and kidney was inhibited by heavy metals and thiol blocking agents. However, inhibition of enzyme activity in the serum was not observed with such inhibitors. Therefore, we suppose that post-proline cleaving enzyme activity in the brain is similar, if not identical, to that in the kidney.

Journal ArticleDOI
TL;DR: In this article, a cyclized cyclization of methyl 3-oxo-8-phenoxy-6-octenoate using Pd(OAc)2-PPh3 as a catalyst to give 2-carbomethoxy-3-vinylcyclopentanone and 2-CARO-4-cycloheptenone was proposed.

Journal ArticleDOI
TL;DR: In this paper, a mechanism involving coordination of dpp via one phosphorus atom and ensuing chelation of dPP accompanied by dissociation of bpy is proposed for the ligand exchange reaction between NiMe2 (bpy) and Ph2P(CH2)3PPh2 (dpp).