Rapid method for preparing a beta-glucan-specific sensitive fraction from Limulus (Tachypleus tridentatus) amebocyte lysate

By separating Limulus amebocyte lysate by cation-exchange chromatography with an SP-Toyopearl 650C column, a fraction insensitive to endotoxin, yet specifically sensitive to beta-glucan, was successfully obtained in the unadsorbed portion. This fraction showed beta-glucan dose-dependent clotting enzyme activity, although no sensitivity to endotoxin. This beta-glucan-dependent reaction showed no interference in the presence of endotoxin, with the fraction also showing sensitivity towards various kinds of beta-glucan, i.e. curdlan, pachyman, laminaran and lichenan. The sensitivity towards curdlan was approximately 10(-10) g/ml.     

Inclusion-water-cluster in a three-dimensional superlattice of gold nanoparticles

Three-dimensional particle crystals made of dicarboxylic thiolate (MSA)-stabilized gold nanoparticles were formed at an air/water interface. FTIR spectra of this supracrystal showed that three well-resolved peaks existed from 3400 to 3550 cm-1 just falling in a region of OH stretching vibrational mode. Precise analysis showed that all these peaks originated from the water cluster included in the interstice of a particle crystal.     

On the correlation of the glass transition temperature of a copolymer with its comonomer sequences

The glass transition temperature of a copolymer depends not only on chemical composition but also on its comonomer sequences. This experimental fact is explained by Barton's and Johnston's equations. Their equations, though complicated, become simple, if a suitable parameter is used to describe the comonomer sequences. It is shown that with these new expressions, their equations can be used to understand glass transition temperatures of two additional types of copolymers, compatible multiblock copolymers and homopolymers with various tacticities treated as steric copolymers.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthdayWe wish to thank the reviewer for his/her kind linguistic improvement of this article.     

Vinylpolymerisation mit Metall-Komplexen. 27. Mitt. Mechanistische Untersuchung der Vinylpolymerisation mit Polyvinylamin-Cu-(II)-Chelaten in Dimethylsulfoxid-Lösung

Ohne Zusammenfassung     

Positive heterotropic cooperativity for selective guest binding via electronic communications through a fused zinc porphyrin array

Upon binding with C60 and diamines, such as 4,4'-bipyridine (bpy) and N,N,N',N'-tetramethylhexane-1,6-diamine (TMHDA), cyclic host 1 possessing two electronically coupled binding sites displays negative homotropic cooperativity and positive heterotropic cooperativity, and their ternary mixtures preferentially form inclusion complexes with hetero-guest pairs 1 supersetC60*bpy and 1 supersetC60*TMHDA under appropriate conditions. Spectroscopic titration profiles in toluene at 20 degrees C demonstrated that the association constants (Kassoc) of C60 with monodiamine complexes 1 supersetbpy (2.8 x 105 M-1) and 1 supersetTMHDA (1.5 x 105 M-1) are 8.5 and 4.5 times greater than that of C60 with guest-free 1 (3.3 x 104 M-1), respectively. On the other hand, mono-C60 complex 1 supersetC60 was 6.1 times more accessible than guest-free 1 toward TMHDA. Absorption spectroscopy in the absence of 1 indicated no direct interaction between C60 and diamines.     

Polymerization of methyl methacrylate under ultrasonic irradiation. Part IV. Effect of ultrasonic irradiation on Grignard catalyst and stereoregularity of the polymers produced in dioxane–tetrahydrofuran mixed solvent

Two series of polymerization of methyl methacrylate with Grignard reagent in dioxane—tetrahydrofuran mixed solvent was carried out under ultrasonic irradiation. In series A, catalyst was added to the mixture of monomer and solvent, and in series B, catalyst was previously mixed with solvent. The effect of ultrasonic irradiation on Grignard catalyst and the microstructure in reacting sites were discussed on the basis of the stereoregularity of the polymers produced. The stereoregularity of the polymers in series A was higher than that in series B. The effect of ultrasonic irradiation on the stereoregularity was completely reversed in series A and B and it increased in the former and decreased in the latter. It was, therefore, assumed that ultrasonic irradiation affected the microstructure in the reacting sites in series A, while it increased the relative amount of R₂Mg which gave polymers with poor stereoregularity in series B.