Polymerization of α-amino acid N-carboxy anhydride. IX. Copolymerization of α-amino acid N-carboxy anhydride in heterogeneous system

Copolymerization of NCA's was undertaken in a heterogeneous system in acetonitrile, which is not a solvent of the polypeptides. The reactivity ratio was calculated by using the Lewis-Mayo equation. Further, the conversion rate in the copolymerization and the configuration of the copolymer produced were compared with those of the copolymerization in the homogeneous system in nitrobenzene, in which the copolypeptides are swollen. The rate of copolymerization in acetonitrile was between the rates of polymerization of the individual monomers. It has been reported that the configuration of the copolymer obtained in dimethylformamide, in which the copolypeptides are swollen, is of the block type. On the other hand, many polypeptides obtained in acetonitrile, which is not a solvent of the copolypeptides, had a random configuration near to an alternating configuration.     

Inhibitory effects of tetragalloylglucose on the complex II of mitochondrial respiratory chain of Ascaris muscle

The effects of tetragalloylglucose (1,2,3,6-tetra-O-galloyl-beta-D-glucose) on purified complex II (succinate-ubiquinone oxidoreductase) of the mitochondrial electron transport system of Ascaris muscle were studied. Both succinate-ubiquinone-1 (Q1) oxidoreductase, and succinate dehydrogenase measured with 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) in the presence of phenazine methosulfate (PMS) were inhibited by tetragalloylglucose. The inhibitions of both reductase activities of complex II were of competitive type, and the inhibitor constant (Ki) for Ascaris complex II (148 nM) was lower than that for rat liver complex II (1.5 microM). Thus, Ascaris complex II is much more sensitive to this inhibitor than the mammalian counterpart.     

Development of a novel potentiometric titration method for determination of polypropylene degradation

In this study, a novel potentiometric titration of hydroperoxide in degraded polypropylene (PP) is proposed. This titration is quite sensitive compared with the conventional ones such as UV and manual titrations, and its detection limit was about 2 meq/kg. The sensitivity was equal to that of molecular weight measurement by GPC for the degraded PP and, in addition, the volatilization behavior of the hydroperoxide could be detected. This titration was found to be very effective for the determination of PP degradation.     

Purification of Food Color Red No. 106 (acid red) using pH-zone-refining counter-current chromatography

pH-Zone-refining counter-current chromatography was successfully applied to the separation of the main components of Food Color Red No. 106 (R-106, acid red, Color Index No. 45100). A 300-mg quantity of sample was separated using the following two-phase solvent system: n-butanol-water, 40 mM sulfuric acid in organic stationary phase and 30 mM ammonia in aqueous mobile phase. The obtained fractions were analyzed by high-performance liquid chromatography and fast atom bombardment mass spectrometry. The separation yielded 261.9 mg of main component of acid red with purity of 99.9%.     

Electrical Conduction Mechanisms of MxPS3, M1−xM'xPS3 and their Intercalation Compounds

Abstract

In the M_xPS₃ and M_1?xM'_xPS₃ systems, the P₂S₆ cluster contributes to the poor electrical conductivity for the compounds in which the energy level of the metal 3d orbital is deeper than those of the P, S 3p orbitals. For the compounds in which metal 3d orbital is closed to P and S 3p orbitals and has mixed valency, the induced mixed valency of P₂S₆, cluster and/or hopping mechanism contribute to the electrical conductivity. In the organic electron donor intercalation into M_xPS₃ and M_1?xM'_xPS₃ compounds, the new intercalation reaction is discovered, in which formation of tris-complexes of metal ions with guest molecules occurs in the host interlayer.     

Total synthesis of ecteinascidin 743

The total synthesis of ecteinascidin 743 (1), an extremely potent antitumor agent, has been accomplished. The synthesis features Ugi's 4CC reaction, intramolecular Heck reaction, phenol-aldehyde cyclization, and acid-induced intramolecular sulfide formation.     

Conservative quantum computing

The Wigner-Araki-Yanase theorem shows that conservation laws limit the accuracy of measurement. Here, we generalize the argument to show that conservation laws limit the accuracy of quantum logic operations. A rigorous lower bound is obtained of the error probability of any physical realization of the controlled-NOT gate under the constraint that the computational basis is represented by a component of spin, and that physical implementations obey the angular momentum conservation law. The lower bound is shown to be inversely proportional to the number of ancilla qubits or the strength of the external control field.