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  • Author or Editor: T. Yamada x
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Abstract  

The thermally induced structural transformation of a hydrogen-bonded crystal formed from an amphoteric molecule of 6-[2-methoxy-4-(pyridylazo)phenoxy]hexanoic acid MeO was studied using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction measurement (XRD). Crystal form of the hydrogen-bonded crystal was measured by single crystal four circle diffractometer (Mo-Kα radiation). As a result, the crystal of MeO was stabilized by many C–H⋅⋅⋅O hydrogen bonds, and the C–H⋅⋅⋅O hydrogen bonds were broken by thermal energy reversibly. After transformation the supramolecular architecture was composed of supramolecular polymer including free-rotation pentamethylene main chains.

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Summary The mixing state of amphiphilic di-block copolymers consisted of poly(ethylene oxide) and poly(methacrylate) having azobenzene moieties in the side chains p(EO)114pMA(Az)24 and poly(ethylene oxide) p(EO)114 was investigated from the viewpoints of isothermal crystallization and nano-scale ordered structure. The chemical potential, which required establishing the constant crystal growth rate, decreased with the p(EO) content up to 60%. The hexagonal packed cylinder structure was observed for the blends with the p(EO) content up to 60% and the lattice spacing of (100) and (110) planes increased with the p(EO) content up to 60%. The blends of amphiphilic p(EO)114pMA(Az)24 and p(EO)114 were miscible without in the p(EO) content below 60%.

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Summary {\rtf1\ansi\ansicpg1250\deff0\deflang1038\deflangfe1038\deftab708{\fonttbl{\f0\froman\fprq2\fcharset238{\*\fname Times New Roman;}Times New Roman CE;}} \viewkind4\uc1\pard\f0\fs20 New explanations are given for two types of irregular thermogravimetric (TG) data. A TG relationship between mass and temperature is derived on the basis of migration behavior of bubbles generated in bulk of sample system, and superposed on that derived on the basis of kinetics of the 4\super th\nosupersub order event, which is superposed on the experimental TG data obtained from three reference papers. This suggests that these TG data are reflecting migration of bubbles. A dependence of TG behavior on heating rate, which is contrary to usual that, is shown and is explained in terms of event-rate determination by boiling. \par }

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Summary Thermally induced structural transformation of fibrous hydrogen-bonded molecular assemblage formed from an amphoteric pyridinecarboxylic acid of 6-[2-propyl- 4-(4-pyridylazo)phenoxy]hexanoic acid (C5PR) was studied using differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermogravimetry (TG). The organized fibrous morphology formed in an aqueous solution was stable at temperatures below 150°C. The ordered crystalline solid phase (K1) of the original fibrous material altered to a disordered crystalline solid phase (K2) at 150°C and subsequently to an isotropic phase (I) at 172°C. In the isotropic state, the C5PR molecule was slowly decomposed by decarboxylation. Once the molecular assemblage was subjected to the mesophase by heating, another ordered crystalline solid phase (K3) appeared reversibly at 17°C. The heat budget analyses by DSC indicated that a conformational entropy change such as the side-chain propyl group and the main-chain pentamethylene unit in the hydrogen-bonded molecular assemblage took place between the two ordered crystalline solid phases K1 and K3.

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Abstract  

Phase transition process of PEOm-b-PMA(Az)n was investigated by the simultaneous DSC-XRD measurement using the synchrotron radiation facility. Four endothermic DSC peaks were observed during heating process. These DSC peaks were assigned to the melting of PEO, the transition from SmX, which is a mixture of super-cooled SmC and crystal, to SmC, from SmC to SmA, and from SmA to isotropic liquid state as determined by XRD profiles. In SmC phase, the liner expansion coefficient calculated from the spacing variation of the smectic layer distance was larger than that of the other phases. This result reflected the fact azobenzene moieties in the long-side chains of PMA(Az)n forming the smectic layers and then they were tilted and stood up during the heating process.

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Abstract  

The effects of nitrogen (N2) pressure on amphiphilic di-block copolymer, PEO114-b-PMA(Az)40, were investigated by scanning transitiometry. The isotropic transition temperature increased with the increase of pressure above 20 MPa. The hydrostatic pressure effects evaluated with the Clapeyron equation were smaller than the value obtained by mercury as a pressurizing medium because the amount of absorbed gas decreases the volume change at the isotropic transition.

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Abstract  

Thermal stability of para (p--) and ortho (o-) isomers was investigated by CRTG and reaction kinetic analysis. The temperature started the mass decrease of o-isomer was about 20C lower than that of p-isomer by CRTG. The activation energies of thermal decomposition of o- and p-isomers were 136.9 and 153.4 kJ mol–1, respectively. The effect of steric hindrance on heat of formation was calculated by AM1 method using Win MOPAC3.0 for the model compound of p- and o-isomers. The lower stability of o-isomer was the results of the steric hindrance between the ethylene unit of aromatic ring and three alkyl chains.

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Abstract  

A technique to determine concentrations of 32P, 33P and 7Be in dissolved and particulate forms, in the upper ocean was developed. By using a large volume in situ filtration and concentration system (LV-FiCS), several tons of seawater at different depths were filtered concurrently through two kinds of filters. The dissolved radionuclides were concentrated onto adsorbents in the LV-FiCS. The radionuclides obtained were further purified by precipitation and ion-exchange chromatography, and quantified by gamma-spectrometry and ultra-low level liquid scintillation counter measurements. The technique was used with good results in a coastal area of Ibaraki, Japan.

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Abstract  

The effects of high pressure carbon dioxide (CO2) on the isotropic transition of three different amphiphilic di-block copolymers, PEOm-b-PMA(Az)n, namely PEO114-b-PMA(Az)40, PEO272-b-PMA(Az)46 and PEO454-b-PMA(Az)47, and on PMA(Az)30 homopolymer have been investigated by scanning transitiometry. Under CO2 pressure, the isotropic transition temperature decreased with the increase of pressure up to around 30 MPa due to CO2 sorption and increased above 40 MPa. Transition entropy of the isotropic transition indicated that the depression of the isotropic transition temperature was caused by the adsorption of CO2 into the azobenzene moieties and that the increase above 40 MPa was caused by the desorption of CO2 into the azobenzene moieties. Comparison between PEOm-b-PMA(Az)n copolymers and PMA(Az) homopolymer clarified PEO domain acted CO2 pathway to approach the equilibrium state rapidly.

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Abstract  

Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/2, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of99Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/3, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material.

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