Hitoo Kakiyama

Characteristics of meso-carbon microbeads separated from pitch

Abstract Mesophase spherules separated by solvent fractionation from heat-treated coal-tar pitch and from heat-treated asphalt at 430°C are named “meso-carbon microbeads”. Characteristics of these mesophase microbeads were studied. The meso-carbon microbeads are classified into three types, type C, type M and type P, corresponding to the raw pitch materials. The chemical composition of type C and type M consists of high molecular weight aromatic hydrocarbons having short side chains of aliphatic hydrocarbons, and that of type P consists of small ring number aromatic hydrocarbons having long side chains of aliphatic hydrocarbons. The shapes of the meso-carbon microbeads are classified into lemon-like and spherical by their shape. The meso-carbon microbeads do not fuse or melt by heat-treatment. The graphitizability of heat-treated meso-carbon microbeads is not high. When the meso-carbon microbeads are heat-treated at 300–500°C in a medium of polynuclear aromatic hydrocarbons (anthracene, pyrene, chrysene and pitch) their behavior is similar to that of mesophase spherules in pitch. However, when the ratio of the meso-carbon microbeads to the polynuclear aromatic hydrocarbon was changed, the behavior of the microbeads was peculiar.

Vaporization of atoms and molecules during heating of cadmium, lead and zinc salts in a carbon tube atomizer

Abstract Vaporization characteristics of atoms and molecules produced during heating of aqueous solutions of Cd, Pb and Zn salts in the carbon tube atomizer are described. Sulfates, nitrates and fluorides are decomposed completely to free atoms without losses. When concentrated halide solutions are employed, gaseous metal chlorides, bromides and iodides are removed partly from the atomizer in the initial atomization phase, and the atomic absorption response is decreased. This loss can be suppressed effectively by adding nitric or sulfuric acid to the halide solutions.

Vaporization and thermal decomposition of transition metal salts in flameless atomic absorption spectrometry with a carbon tube atomizer

Abstract Vaporization and thermal decomposition of Cr, Mn, Fe, Co, Ni and Cu salts were investigated by measuring the absorption spectra observed when aqueous solutions of these salts were heated in the carbon tube atomizer. Gaseous metal halides are vaporized in the atomizer at temperatures above 300–500° C. SO 2 and NO are produced by thermal decomposition of metal sulfates and nitrates, respectively. The vaporization of metal halides is also confirmed by the spectra for solutions of metals in hydrochloric acid and for mixtures of metal nitrates and ammonium halides.

Chromatographic separation of metal ions on a macroreticular cation-exchange resin with hydrochloric acid N aqueous acetone solution

Abstract Forced-flow chromatography on a cation-exchange resin has been used to obtain rapid separations of metal ions, such as Cd(II), Zn(II), Fe(III), Pb(II), Cu(II), Co(II) and Mn(II). The macroreticular resin used provides rapid separations in hydrochloric acid-acetone media covering acid and acetone concentration ranges of 0.1–1.88 M and 70–96%, respectively. On-stream addition of a colour-forming reagent provides continuous detection and quantitation of the eluted metals.

Chemical effects in X-ray Kα and Kβ emission spectra of sulfur in organic compounds

Abstract A systematic investigation of the chemical effects in the sulfur X-ray K emission spectra of many organic compounds was carried out using a two-crystal X-ray spectrometer. The well-known rule that the sulfur Kα emission peak shifts to higher energies with increasing sulfur oxidation state was fully confirmed in the chemical shifts of the Kα1 and Kα4 satellite peaks. Some attempts were also made to reveal possible regularities regarding changes in the high resolution Kβ spectra with the chemical bonding of sulfur. The types of sulfur-oxygen bonds are characterized by the chemical shift of the main Kβ1 line and the intensity ratio Kβ′/Kβ1. The chemical bonding form of divalent sulfur can be estimated roughly from the positions of the Kβx and Kβ1 lines and the intensity ratio Kβx/Kβ1.

E.s.r. study of vanadyl complexes in various carbonaceous materials at high temperature

Abstract E.s.r. spectra of vanadyl complexes in various carbonaceous materials were measured in a range between room temperature and 435 °C. The e.s.r. spectrum of vanadyl complex doped in Taching reduced crude was a slow tumbling pattern at temperatures between 60 °C and 225 °C. By the rapid freezing technique, it became clear that the vanadyl complex in Taching residue was oriented to the magnetic field in its temperature range. Further, activation energies for rotations of vanadyl complexes in those carbonaceous materials were estimated from Arrhenius plots of the correlation times. Those carbonaceous materials were classified into two groups according to values of the activation energies. This classification was consistent with that based on mesophase textures of the cokes made from them.

Microscopic Study on the Molecular Arrangements in the Smectic A, B and C Modifications

Abstract The molecular arrangements in three smectic modifications, i.e., the smectic A, B and C states are discussed on the basis of optical observations of smectic spherulites, which were fixed in a very viscous polymer matrix. The observed microscopic patterns for the smectic A state support the conventional idea that the smectic A state has a molecular arrangement such that the long molecular axis lies perpendicular to the layers. In the smectic B state, similar patterns to the smectic A were observed, suggesting a similar molecular arrangement to the smectic A state. On the other hand, the smectic C state exhibits strikingly different patterns from those of the smectic A and B states. Twisted smectic layers are proposed for the molecular arrangement of the smectic C state in order to reasonably explain all the observed microscopic patterns.

Cation-exchange chromatography of bismuth(III), cadmium(II), indium(III) and zinc(II) ions with hydrochloric acid in aqueous acetone solution

Abstract Trace amounts of bismuth(III), indium(III), cadmium(II) and zinc(II) were separated from each other by stepwise elution chromatography and detected by continuous flow spectromery. A macroreticular cation-exchange resin was used to achieve rapid separation in hydrochloric acid-acetone covering the acid and acetone concentration ranges 0.1–0.64 M and 18–80%, respectively.

Studies on the Molecular Arrangement in Liquid Crystals by Polarization of Fluorescence

Molecular arrangements in liquid crystals have been studied by the method of fluorescence polarization. Fluorescence molecules with a highly optical anisotropy, dispersed homogeneously in a liquid crystalline material are used as a probe to detect the molecular alignment in the liquid crystal« The angular distribution of the polarized components of the fluorescence gives useful information on the extent as well as the types of molecular orientation. Examples of the application of this method are given for the determination of the molecular arrangement in liquid crystals at the phase transitions from the isotropic liquid state through mesomorphic state to the crystalline state. The results obtained for the nematic state of para-n-octyloxybenzoic acid suggest that the molecules can be regarded as adopting almost perfect parallel alignment over regions much larger than the molecular dimensions. The observed angular distribution patterns of the polarized components of fluorescence can be well explained by assuming a molecular arrangement of uniaxial prolate ellipsoid for the nematic state. Discussion is briefly given to the angular distribution patterns for the smectic and crystalline states.