On the inverse Sturm-Liouville problem for spatially symmetric operators,II

Using a third order Picard-Fuchs equation we show that a certain two parameter family of planar vectorfields for parameter values in a certain cone has a unique limit cycle, which is born from a Hopf bifurcation and dies in a saddle connection. This removes a superfluous hypothesis in Theorem 3.2, Chapter 13 of S. N. Chow and J. K. Hale (“Methods of Bifurcation Theory,” Springer-Verlag, New York, 1982).     

Supramolecular hydrogels and organogels based on novel l-valine and l-isoleucine amphiphiles

New low-molecular-weight gelators based on l-valine and l-isoleucine gelators, which have a positively charged terminal group, can gel not only pure water and aqueous solutions containing inorganic acids and salts but also some organic solvents and oils.     

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.     

Electrophoresis of mutant proteins in inherited diseases

The electrophoretic approaches for detection of mutant proteins in inherited diseases are briefly reviewed and discussed. Mutation of a protein, known to be associated with a specific inherited disease, is detected by immunoblotting, immunoprecipitation or enzyme staining, combined with various electrophoretic techniques. Some instrumental and technological devices for two-dimensional electrophoresis have been reported for the screening of mutant proteins in diseases of currently unknown etiology.     

Stepwise Synthesis of Fullerene Cyclopentadienide R(5)C(60)(-) and Indenide R(3)C(60)(-). An Approach to Fully Unsymmetrically Substituted Derivatives

Fullerene cyclopentadienide (PhCH(2))(2)Ph(3)C(60)(-) and indenide (PhCH(2))(2)PhC(60)(-), each bearing two different organic groups, were efficiently synthesized through regioselective reactions of 1,4-(PhCH(2))(2)C(60) with an organocopper reagent (PhMgBr/CuBr.SMe(2)) or a Grignard reagent (PhMgBr) followed by deprotonation with KO(t)()Bu.     

Preparation of substituted benzoyltrimethylsilanes by the palladium-catalyzed silylation of substituted benzoyl chlorides with hexamethyldisilane

A direct preparative route to benzoyltrimethylsilane has been found by the reaction of benzoyl chloride with hexamethyldisilane in the presence of a specified palladium(II) complex as catalyst.     

Comparative pharmacokinetics of 67Ga among the different routes of injection

The pharmacokinetic study of 67Ga-citrate (67Ga) following intravenous (i.v.), subcutaneous (s.c.) and intraperitoneal (i.p.) injection was performed in anesthetized rats using the repeated blood sampling method by cannulation technique into the external jugular vein. The disappearance of 67Ga from the blood following i.v. and s.c. injection was best fit a three-exponential equation. There was no significant difference between the areas under the curves following i.v. and s.c. injection of 67Ga. In the case of i.p. injection, the disappearance of 67Ga from the blood was described by a two-exponential equation. However, the maximum blood radioactivity was very low, and the disappearance rate of 67Ga from the blood was extremely slow compared to the other routes of injection. The conclusion from these results was that s.c. injection was as suitable as i.v. injection, but i.p. injection was not appropriate for the distribution study of 67Ga such as scintigraphy or autoradiography. However, i.p. route may be available for a special experiment which needs the long-time retention of 67Ga in the blood.     

Synthetic approach toward antibiotic tunicamycins — VI total synthesis of tunicamycins

Tunicamycins and their eight analogs have been synthesized by condensation of a N-acetyl-D-glucosamine derivative and an anomeric chloride of tunicaminyl uracil, followed by deprotections and N-acylation.     

Selective flow-injection determination of methanol in the presence of ethanol based on a multi-enzyme system with chemiluminescence detection

A highly selective flow-injection system was developed for the determination of methanol. The system consisted of three immobilized enzymes with luminol chemiluminescence detection. First, methanol was oxidized in the presence of alcohol oxidase to yield formaldehyde and hydrogen peroxide. The hydrogen peroxide produced was then destroyed by catalase. The formaldehyde formed in the first stage was further oxidized by NAD⁺-formaldehyde dehydrogenase. The NADH formed was oxidized by 1-methoxy-5-methylphenazinium methylsulphate (1-MPMS), and finally the reduced 1-MPMS was spontaneously oxidized and hydrogen peroxide was produced. The concentration of the hydrogen peroxide produced, which was proportional to the initial concentration of methanol, was determined by luminol chemiluminescence. The determination range was from 0.1 to 100 mg l⁻¹ and the response time was less than 2 min per sample with a relative standard deviation of less than 3%. The system showed good selectivity for methanol; the response was ca. 50 times higher than for ethanol.