Effect of molecular weight distribution on the liquid-liquid phase separation behavior of polydispersed polyethylene solutions at high temperatures

The phase behaviors of the hexane + polydispersed polyethylene (PE) systems were measured to clarify the effect of the molecular weight distribution (MWD) of PE on liquid-liquid (LL) phase boundaries. The weight fraction for the PE portion of a maximum LL phase separation pressure in the LL phase boundary decreased as the polydispersity of PE increased. Moreover, depression of the phase separation pressure from the maximum phase separation pressure on the higher PE weight fraction side was more drastic as the polydispersity of the PE increased. The LL phase boundaries were correlated using the Sanchez-Lacombe equation of state (S-L EOS). For the correlations, the polydispersed PEs were regarded as mixtures of 16 types of monodispersed PEs with different molecular weights, and the characteristic parameters of the S-L EOS, P*, ρ* and T*, were assigned the same values for all monodispersed PEs even though the molecular weights differed. However, the interaction parameters of the hexane-PE pairs depended on the molecular weight of the PE and the temperature. The correlated results capably reproduced the effect of the MWD of the PE on the LL phase boundaries for the hexane + polydispersed PE systems.     

Molecular functions of PsbP and PsbQ proteins in the photosystem II supercomplex

The PsbP and PsbQ proteins are extrinsic subunits of the photosystem II (PSII) supercomplex, which are found in green plants including higher plants and green algae. These proteins are thought to have evolved from their cyanobacterial homologs; cyanoP and cyanoQ respectively. It has been suggested that the functions of PsbP and PsbQ have largely changed from those of cyanoP and cyanoQ. In addition, multiple isoforms and homologs of PsbP and PsbQ were found in green plants, indicating that the acquisition of PsbP and PsbQ in PSII is not a direct path but a result of intensive functional divergence during evolution from cyanobacterial endosymbiont to chloroplast. In this review, we highlight newly introduced topics related to the functions and structures of both PsbP and PsbQ proteins. The present data suggest that PsbP together with PsbQ have specific and important roles in coordinating the activity of the donor and acceptor sides of PSII and stabilizing the active form of the PSII-light-harvesting complex II (LHCII) supercomplex.     

Micropattern of GeO2/GeC lines prepared by UV irradiation and heat treatment of polygermane copolymers of methylphenylgermylene/phenylgermyne units

Upon ultraviolet irradiation of polygermane copolymers of methylphenylgermylene/phenylgermyne units (PhMeGe)_n(PhGe)_m in air, the germanium–germanium bond in the copolymer film changed into a digermoxane chain. Laser flash photolysis of the copolymer film showed the intermediacy of polygermyl radicals generated by Ge–Ge bond homolysis. The XPS showed the formation of germanium carbide (GeC) and germanium dioxide (GeO₂) upon heating the unirradiated and irradiated copolymer (PhMeGe)_n(PhGe)_m films, respectively. A relatively high-resolution micro- pattern of GeC/GeO₂ was obtained by combining the photochemical and thermal properties of the copolymers of methylphenylgermylene/phenylgermyne units. © 1997 John Wiley & Sons, Ltd.     

Synthesis of Isomeric Tb3+-Phthalocyanine Double-Decker Complexes Depending on the Difference in the Direction of Coordination Plane and Their Magnetic Properties

A C_4h symmetrically substituted phthalocyanine, 1,8,15,22-tertrakis(2,4-dimethylpent-3-oxy)phthalocyanine (H₂TdMPPc), was used to synthesize Tb³⁺-phthalocyanine double-decker complexes ([Tb(TdMPPc)₂]s). Because H₂TdMPPc has C_4h symmetry, S,S, R,R, and meso isomers of [Tb(TdMPPc)₂] were obtained depending on the difference in the direction of the coordination plane of two C_4h-type phthalocyanines with respect to a central Tb³⁺ ion. We investigated the physical properties of these [Tb(TdMPPc)₂] isomers, including their single-ion magnetic properties, and found that the spin-reversal energy barrier (U_eff) of the meso isomer was apparently higher than that of the enantiomers. Detailed crystal structural analyses indicated that the meso isomer has a more symmetrical structure than do the enantiomers, thereby suggesting that the higher U_eff of the meso isomer originated from the more highly symmetrical structure.