Showing papers by "Tokyo Institute of Technology published in 1971"

Infrared Spectra of Poly(acetylene)

Abstract: The infrared spectra of poly(acetylene), poly(acetylene-d2), copoly(acety+acetylene-d2), and copoly(acetylene+acetylene-d1+acetylene-d2) prepared by the Ti(OC4H9)4–Al(C2H5)3 system over a wide temperature range (ca. −100 to 180°C) are reported. A tentative assignment of the observed spectra is made on the basis of model structures in which infinite planar chains of all trans, all trans–cisoid, and all cis–transoid configurations are assumed. The spectral data are best interpreted on the basis of an all cis-transoid (or an all trans-cisoid) structure for the polymers prepared at temperatures lower than −78°C, and an all trans structure for the polymers prepared at temperatures higher than 150°C.Simplified calculations of the C-H and C-D out-of-plane deformation frequencies are made for various model chains. It has been concluded from a comparison of the observed and calculated frequencies that the cis-opening of the triple bond occurs in a polymerization reaction with the Ti(OC4H9)4–Al(C2H5)3 catalyst system at low temperatures.

Reduction of Organic Compounds with NaBH4-Transition Metal Salt Systems. IV. Selective Hydrogenation of Olefines in Unsaturated Esters

Abstract: Hydrogenation of unsaturated esters was performed with NaBH4-transition metal salt systems. Nickel, cobaltous and cupric salts were effective metal salts for reduction of olefinic esters. Hydrogenation of the olefinic bonds proceeded quantitatively to afford the corresponding saturated esters when using one of the following pairs : NiCl2·6H2O (0.1 mole)-NaBH4 (2 moles), CoCl2·6H2O (0.25 moles)-NaBH4 (10 moles) and CuCl2.2H2O (0.3 moles)-NaBH4 (6 moles) per mole of I.

Experimental Studies of Structural Phase Transitions in CsPbCl3

Abstract: Some experimental investigations have been made in order to understand the nature of phase transitions in the perovskite-type crystal CsPbCl 3 . Measurements of the birefringence and conoscopic observations confirm three phase transitions occurring at 37°C, 42°C and 47°C, respectively. The crystal system in each phase and the superstructure below 37°C are determined from the results of these measurements and an X-ray work. A dielectric measurement shows that CsPbCl 3 is neither ferroelectric nor antiferroelectric in any of the phases. The transition entropies estimated from the result of a specific heat measurement are considerably smaller than that reported by Moller. The elastic compliance measured by the method of composite oscillator shows anomaly at each transition point. Temperature-dependent Raman spectra demonstrate the existence of “soft” modes which are overdamped near the transition temperatures. The nature of these phase transitions is discussed on the basis of the experimental results.

Orthogonal Transform Coding System for Television Signals

Abstract: We discuss orthogonal transformation as a method to compress frequency bandwidth for TV signals. We indicate that the slant orthogonal transformation derived from Hadamard matrix is most advantageous for compression of TV signal bandwidth. Results of simulation show that unweighted Sp-p/Nq rms of approximately 32 dB was obtained with 2.5 bits per sample on picture showing human face.

Intensity of Magnon Sidebands

Abstract: A general formula is derived for the integrated intensity of magnon sidebands in a two-sublattice antiferromagnet. The integrated intensity variation with temperature is calculated under the (random phase) decoupling approximation. Predicted values of the integrated intensity coincide with that obtained in the spin wave theory at low temperatures and that in the pair spectra theory at high temperature limit. The theory is applied to the rutile type antiferromagnets and numerical calculations are presented for magnon sidebands in MnF 2 .

Magnetic Properties of Single Crystals Cr2-δTe3

Abstract: The magnetic transitions of the Cr-Te system has not been explained by a suitable model. Therefore, the magnetic properties of the single crystals of Cr 2-δ Te 3 , prepared by the chemical transport method, were investigated. From the measurement of the magnetic susceptibility above room temperature S =3.0 8 /2 per Cr-ion is obtained, which is coincident with the spin only value of Cr 3+ ion and a ferromagnetic transition is found to be expected. While, from the extrapolated magnetization value to 0 K, the Bohr magneton numbers per Cr-ion are 2.0 2 and 1.9 6 µ B for Cr 1.96 Te 3 and Cr 1.98 Te 3 , respectively, and these values are in contradiction to those expected from the magnetic susceptibility. Qualitative considerations about these anomalous magnetic transition are given.

Topographic Study on Ferroelectric NaNO2 Crystals. I. Structure of 180° Domain Walls

Abstract: 180° domain walls have been observed on X-ray diffraction topographs of sodium nitrite (NaNO 2 ) single crystals. Contrast of the walls depends on the kinds of the Bragg reflections used for the topographs. The reflection dependence of the contrast suggests that the contrast is produced neither by strain field around the domain walls nor misorientation of the lattice in the domain walls. A model of the crystal structure of the walls which is consistent with the observed contrast is presented. Thickness of the walls is estimated as the order of 1µm on X-ray topographs and 0.3∼1.0 µm on electron micrographs of replica films extracted from polar surfaces of the crystal.

0 + States in Mo Isotopes from (p,t) Reactions and Anomalies in the New Transitional Region

Abstract: We have used $^{92,94,96,98,100}\mathrm{Mo}(p,t)$ reactions to investigate the ${0}^{+}$ states in even Mo isotopes. The appearance of low-lying excited ${0}^{+}$ states in $^{98,100,102}\mathrm{Mo}$ with large two-neutron transfer strengths, together with the systematics of the lowest ${2}^{+}$ states, suggests the existence of a new transitional region. The large cross section for the excited ${0}^{+}$ state in the reaction $^{100}\mathrm{Mo}(p,t)^{98}\mathrm{Mo}$ may be able to explain the anomaly in the $l=0$ spectroscopic factors in $^{98}\mathrm{Mo}(d,p)$ and $^{100}\mathrm{Mo}(d,t)$ reactions.

13C–{1H} Nuclear Magnetic Resonance Spectroscopy of Poly(methyl methacrylate)

Abstract: The 13C–{1H} high-resolution nuclear magnetic resonance spectra were measured for poly(methyl methacrylate). The spectra clearly split corresponding to dyad, triad, tetrad, and pentad placements. The relative intensity of every peak for the spectrum of a polymer prepared with 9-fluorenyllithium in tetrahydrofuran/toluene (80/20) at −23°C was reasonably interpreted by the Bernoulli trial model.The nuclear Overhauser effect due to total proton decoupling did not affect the relative intensities among the peaks assigned to chemically equivalent carbons except for the difference in stereochemical configuration. This was confirmed by comparison between the relative intensities of the above-mentioned polymer and by comparison between those of 13C–{1H} and of 1H resonance of the polymer.The microtacticity determined by 13C–{1H} spectra of a polymer prepared with 9-fluorenyllithium in tetrahydrofuran/toluene (4/96) was fairly well interpreted by the stereoblend model, but by neither first-order nor second-order Markovian model.

Thermal Study of Blended Systems of Poly(methyl methacrylate) and Poly(vinyl acetate)

Abstract: Heats of solution of blended and non-blended systems of poly(methyl methacrylate) and poly (vinyl acetate) were measured at 28°C. From the difference between them the heat of blending was estimated according to Hess’s law. The absolute value for the blend prepared by freeze drying, which is thought to be molecularly mixed, was smaller than that for the blend, which shows partial phase separation. This unexpected result is explained by the differences of specific heat behaviour between the systems.

Thermodynamic Studies on the Glass Transition and the Glassy State of Polymers. I. Pressure Dependence of the Glass Transition Temperature and Its Relation to Other Thermodynamic Properties of Polystyrene

Abstract: The pressure dependence of the glass transition temperature, Tg, and the coefficients of thermal expansion, α, and the compressibility, β, of polystyrene were measured. For the same sample, DSC measurement was also carried out, to obtain specific heat, Cp. From the results, it was confirmed that the relation (∂Tg/∂P)≅TVΔα/ΔCp<Δβ/Δα was valid, in accordance with our theory based on a hole model for polymer liquids and glasses with an assumption of iso-configurational entropy at Tg. Changes of specific heats at Tg associated with intrasegmental interactions and inter-segmental ones were calculated separately by the use of the theory, and ΔCpintra=0.041 and ΔCpintra=0.036 cal/gK were obatined.

The Synthesis of Di-μ-thio-dithio-bis (dialkyldithiocarbamates) Dimolybdenum (V) and Their Effects on Boundary Lubrication

Abstract: Sulfurized molybdenum dialkyldithiocarbamates prepared from molybdenum trioxide, carbon disulfide, and dialkylamine were separated by chromatography into three components. A new compound, the analytical result of which showed (R2NCSS)2Mo2S4 (where R=ethyl, isopropyl, n-butyl, and isobutyl), was obtained by phosphorus pentasulfide treatment of a xylene solution of sulfurized molybdenum dialkyldithiocarbamate. The mechanism of the pyrolysis of these molybdenum complexes was investigated. EP properties of the complexes blended in Li-12 hydroxystearate grease were tested using a Timken and Shell 4-Ball Machine.Thermogravimetric analysis in a stream of nitrogen indicated that the complexes decomposed in two distinct stages. The first stage decomposition occured at a relatively low temperature because of dealkylation, and the second decomposition occured at a higher temperature. It was confirmed that molybdenum disulfide crystals were formed by the pyrolysis of the complexes in vacuo or in an atmosphere of nitrogen. The complexes blended in the grease showed excellent EP performance and antiwear properties in laboratory bench tests.

The catalytic activity of the poly‐L‐lysine‐copper(II) complex on the oxidation of 3.4‐dihydroxyphenylalanine

Abstract: The poly-L-lysine- (PLL) and poly-DL-lysine-copper(II) complexes were used as the catalysts for the oxidation of 3.4-dihydroxyphenylalanine. The catalytic activity of poly-L-lysine-copper(II) complex (PLL-Cu(II)) was found to be larger than that of bis(ethylenediamine)-copper(II) at both pH 6.9 and 10.5. The catalytic activity was discussed on the basis of some kinetic data. The oxidation was presumed to proceed through the formation of a reaction intermediate between the catalyst and the substrate. It was also revealed that the oxidation was catalyzed asymmetrically when the PLL-Cu(II) was used as the catalyst at pH over 10.5. The asymmetric oxidation was presumed to be ascribed to the helical structure of PLL-Cu(II) in the aqueous solution of pH 10.5. Die Kupfer(II)-komplexe von Poly-L-lysin (PLL) und Poly-DL-lysin wurden als Katalysatoren fur die Oxydation von 3.4-Dihydroxy-phenylalanin verwendet. Es wurde gefunden, das die katalytische Wirksamkeit des Poly-L-lysin-kupfer(II)-komplexes (PLL-Cu(II)) sowohl bei pH 6,9 als auch bei pH 10,5 groser ist als die des Kupfer(II)-diathylendiamin-Komplexes. Auf Grund kinetischer Daten wird angenommen, das die Oxydation uber die Bildung eines Zwischenproduktes aus dem Katalysator und dem Substrat verlauft. Auserdem wurde gefunden, das die Oxydation asymmetrisch katalysiert wird, wenn PLL-Cu(II) bei einem pH-Wert uber 10,5 verwendet wird. Es wird angenommen, das die asymmetrische Oxydation der Helixstruktur des PLL-Cu(II) in der wasrigen Losung von pH 10,5 zuzuschreiben ist.

Formation and properties of poly‐L(DL)‐lysine‐copper(II) complexes

Abstract: Water-soluble poly-L-lysine- and poly-DL-lysine-copper(II) complexes were prepared in aqueous alkaline solutions. The complex-formations of poly-L-lysine and poly-DL-lysine with cupric ions in aqueous solutions were studied with pH titration and electronic spectroscopy and measurements of optical rotatory dispersion, circular dichroism and solution viscosity. From the results it was revealed that the poly-L-lysine forms two kinds of complexes, being formed on the degree of neutralization α 0.5, respectively. The former complex consists of a cupric ion coordinated with four amino nitrogen atoms of the side chains. Some extents of helical conformation of poly-L-lysine are held after the complex formation with cupric ions at a pH over 10. The results on the poly-L-lysine-copper(II) complexes were compared with those on the poly-DL-lysine-copper(II) complexes. Es wurden wasserlosliche Kupfer(II)-komplexe von Poly-L-lysin und Poly-DL-lysin in wasrigen, alkalischen Losungen hergestellt. Die Komplexbildung von Poly-L-lysin und Poly-DL-lysin mit Kupfer(II)-ionen in wasriger Losung wurde durch pH-Titration, durch Elektronenspektroskopie, durch Messungen der optischen Rotationsdispersion, des Circulardichroismus und der Losungsviskositat untersucht. Aus den Versuchsergebnissen geht hervor, das das Poly-L-lysin zwei Arten von Komplexen bildet, die eine bei einem Neutralisationsgrad α 0,5. Beim erstgenannten Komplex sind einem Kupfer(II)-ion vier Aminostickstoffatome der Seitenketten koordiniert. Ein gewisser Anteil der Helixkonformation des Poly-L-lysins bleibt auch nach Komplexbildung mit Kupfer(II)-ionen bei einem pH uber 10 erhalten. Die Eigenschaften der Komplexe des Poly-L-lysins und des Poly-DL-lysins werden verglichen.