Kunio Hikichi

High-resolution solid-state 13C nuclear magnetic resonance study on poly(vinyl alcohol)/poly(vinylpyrrolidone) blends

Abstract The miscibility and domain structure of poly(vinyl alcohol)/poly(vinylpyrrolidone) (PVA/PVP) blends are investigated by high-resolution solid-state 13 C nuclear magnetic resonance methods. The observed 13 C spectra and the intermolecular cross-polarization of the blends suggest a hydrogen-bonding interaction between the two polymers. 1 H T 1 and T 1 ϱ results indicate that the blends are miscible at all compositions on a scale of 200–300 A. On a scale of 20–30 A, however, the miscibility of the blends depends significantly on the composition. When the PVA composition is more than 46 wt%, the blends are composed of two phases, an amorphous miscible phase of PVP plus PVA and a pure PVA phase. The crystallinity of the PVA phase decreases rapidly with decreasing PVA composition. When the PVA composition is less than 46 wt%, the blend is completely miscible. The composition of PVA phase in the blends was inferred from the results of 1 H T 1 ϱ .

Effects of blending on local chain dynamics and glass transition: Polystyrene/poly(vinyl methyl ether) blends as studied by high‐resolution solid‐state 13C nuclear magnetic resonance spectroscopy

To evaluate effects of blending on molecular motion of the individual polymer components in a compatible polymer blend, polystyrene/poly(vinyl methyl ether)(PS/PVME), the temperature dependence of 13C nuclear magnetic resonance linewidth for CH carbon resonance of PVME was studied under conditions of magic‐angle spinning and proton dipolar decoupling. The observed temperature dependence was satisfactorily explained by assuming the following effects of molecular motion: (1) averaging the dispersion of isotropic chemical shifts in the glassy state and (2) the interference between local anisotropic motion and high‐power proton decoupling. The activation parameters for motion of PVME of the blends were determined, and the compositional dependence is discussed. It is concluded that microscopically homogeneous mixing is achieved for PS/PVME blends.

Constitution of two coloring matters in the flower petals of Carthamus Tinctorius L.

Abstract Structures of the safflower red pigment carthamin and the yellow pigment safflor yellow A are shown to be expressed by 3 and 4 respectively, mainly on the basis of spectroscopic evidence.

Atomic force microscopic studies on the structure of bovine femoral cortical bone at the collagen fibril-mineral level.

The structure of cortical bone at the collagen-mineral level was investigated by means of atomic force microscopy. Surfaces of the specimens treated with collagenase and ethylenediaminetetraacetic acid (EDTA) were examined. Images of blob-like objects observed in intact specimen became clearly outlined after collagenase treatment; the sizes of the blob decreased, suggesting that each blob had been fragmented by the collagenase treatment. Following EDTA treatment of an intact specimen, an image of thread-like objects appeared; the thread was partly constructed by trains of blobs and the other parts of the threads had a periodic pattern along its longer axis. The period was almost equal to the collagen D-period of the Hodge–Petruska model, indicating that the threads are collagen fibrils and that the blobs are related to the mineral phase in bone. It was concluded that minerals were deposited on and along collagen fibrils. A decorated collagen fibril model for the spatial relationship between mineral and collagen fibril was proposed. According to our model, the mineral inside the collagen fibril is about one forth of the extrafibrillar mineral.

High-resolution solid state 13C n.m.r. study of the interpolymer interaction, morphology and chain dynamics of the poly(acrylic acid)/poly(ethylene oxide) complex

The interpolymer interaction, morphology and chain dynamics of the poly(acrylic acid)/poly(ethylene oxide) (PAA/PEO) complex are examined by using 13C CP/MAS n.m.r. methods. By analysing 13C CP/MAS spectra of the complex we conclude that there exist three hydrogen bonding forms for the carboxyl group of PAA, namely: (1) the complex form, interpolymer hydrogen bonding between PEO molecules; (2) the dimeric form, intrapolymer hydrogen bonding within PAA molecules; and (3) the free form, no particular form of hydrogen bonding. The morphology of the complex is investigated by the 1H spin-lattice relaxation time in the laboratory frame (T1), and that in the rotating frame (T1ρ). We found that the domain sizes of the three hydrogen bonding forms of PAA are less than a few tens of angstroms, and the PAA/PEO complex is miscible on a molecular level. Further, temperature dependence of 13C linewidth (T2) is examined to study effects of complexation on the molecular motion of the component polymers. The temperatures at which the maximum linewidths are observed for the main chain carbon of PEO and PAA in the PAA/PEO complex are 310 and 362 K, respectively. This indicates that the motional heterogeneity is present in spite of a single Tg for the PAA/PEO complex. Further, we discuss the structural difference between the poly(methacrylic acid)/PEO complex and the PAA/PEO complex.

The structure and physicochemical properties of rat liver macrophage migration inhibitory factor.

We expressed rat macrophage migration inhibitory factor (rMIF) in E. coli using the cDNA isolated from a rat liver cDNA library. rMIF specifically bound glutathione (dissociation constant = 500 microM). We purified rMIF homogeneously on SDS-PAGE by S-hexylglutathione Sepharose affinity column chromatography and Sephadex G-100 column chromatography. The amino-acid sequence of rMIF was highly homologous to that of human MIF from a T-cell line; only a single amino-acid residue was substituted if conservative amino-acid substitutions were involved. The molecular weight of rMIF was calculated to be 12.4 kDa and 23.6 kDa by SDS-PAGE and analytical ultracentrifugation, respectively. Thus, it was concluded that the native rMIF formed a homodimeric structure. Proton nuclear magnetic resonance (1H-NMR) study revealed that rMIF was less thermostable (the denaturing temperature was from 50-60 degrees C) than human MIF (the denaturing temperature is about 80 degrees C (Nishihira et al. (1993) Biochem. Mol. Biol. Int. 31, 841-850). The secondary structure of rMIF evaluated by 1H-NMR experiments revealed that the contents of alpha-helix, beta-strand, and coil were 13.8%, 55.6%, and 30.6%, respectively.

High-resolution solid-state 13C nuclear magnetic resonance study of a polymer complex: poly(methacrylic acid)/poly(ethylene oxide)

Abstract The inter-polymer interaction, morphology and molecular motion of the poly(ethylene oxide)/ poly(methacrylic acid) (PEO/PMAA) complex were investigated by measuring various nuclear magnetic resonance parameters, such as 13 C chemical shift, 1 H T 1 , 1 H T 1 ρ , 1 H T 2 and 13 C T 2 . For the complex, we observed two peaks for the carboxyl carbon of PMAA. We assigned the higher-field resonance to the carboxyl group that forms hydrogen bonds to PEO (the complex form), and the lower-field one to the group that forms hydrogen bonds among PMAA (the dimeric form). It is shown that, for temperatures within 100 K below T g , the complex form easily breaks up and rearranges to the dimeric form. For the complex, the 13 C T 2 and 1 H T 2 reveal that PEO is mobile, whereas PMAA is rigid. This different mobility between PEO and PMAA may facilitate breakage of the hydrogen bonding between PEO and PMAA. Examination of 1 H spin diffusion in the complex reveals that the distance between PEO and PMAA in the complex is similar to that between PEO and PMAA in the dimeric form. These results show that the PMAA in the dimeric form does not aggregate to form a domain structure, and that the PEO/PMAA complex is miscible on a segmental scale. Furthermore, the thermal degradation of PMAA in the complex was examined. Dehydration occurs in the dimeric form to produce anhydride, and the reaction temperature is much lower than that of pure PMAA.

An automatic diffraction data collection system with an imaging plate

An automatic diffraction data collection system with an imaging plate has been developed for protein crystallography. The system works in a similar way to the conventional rotation camera method, but in full online mode. After exposure to the X-ray beam, the imaging plate (100 mm radius) rotates whilst a reading head scans across the plate to measure the stimulated luminescence in a record-player-like manner. During the next period of exposure, the image taken immediately before is processed in parallel. The system has been tested using both peptide and protein crystals and has been proven to work successfully.

Relaxation phenomena of poly-γ-benzyl-L-glutamate, poly-γ-methyl-L-glutamate, and copoly(γ-methyl-L-glutamate, γ-benzyl-L-glutamate)

Abstract Relaxation phenomena of poly-α-amino acids in the solid state have been investigated using poly-γ-benzyl-L-glutamate (PBLG), poly-γ-methyl-L-glutamate (PMLG), and copoly (γ-methyl-L-glutamate, γ-benzyl-L-glutamate) (PMBG) by means of dielectric, dynamic mechanical, NMR, dilatometric, and X-ray diffraction measurements at temperatures between −196 and 180°C. Each of the samples exhibits two relaxation regions, one at room temperature (β-relaxation) and the other in the range from −150 to −100°C (γ-relaxation). The γ-relaxation is attributed to motion of the side chains with small amplitude. The β-relaxation is due to large-scale motion of the side chain. It has been found that the β-relaxation is well described by the WLF-equation. The intensity of the X-ray diffraction peak at 2θ = 7° for PBLG increases with increasing temperature, which is similar to results obtained in small-angle X-ray scattering for polymer crystals consisting of two phases, amorphous and crystalline. A break point is observe...

Chemical constitution of safflor yellow B. A quinochalcone C-glycoside from the flower petals of Carthamus tinctorius L.

Abstract The chemical constitution of safflor yellow B, a quinochalcone glycoside from the flower petals of Carthamus tinctorius L , has been characterized as 1, mainly on the basis of spectral means.