Electrochromatographic enantioseparation using chiral ligand exchange monolithic sol-gel column

This paper describes the development of a monolithic sol-gel column modified with l-hydroxyproline as a ligand exchange chiral stationary phase. It has been demonstrated that the monolithic chiral stationary phase can be used for the enantioseparation of dansyl amino acids, free amino acids, hydroxy acids, and dipeptides by capillary electrochromatography and micro-liquid chromatography. The recommended mobile phase was acetonitrile/0.50 mM Cu(Ac)₂-50 mM NH₄Ac (7:3) adjusted to pH 6.5. The characteristics of the monolithic column using hydroxyproline as chiral selector in CEC have been discussed.     

RPA equation embedded into infinite-dimensional Fock space F ∞

To clear up both algebraic and geometric structures for integrable systems derived from self-consistent field theory, in particular, geometric aspect of the random-phase-approximation (RPA) equation is exhibited on the basis of the viewpoint of symmetry of the evolution equation. The RPA equation for an infinite-dimensional Grassmannian is constructed.     

Methods of analysis for chemicals that promote/disrupt cellular signaling.

Methods of analysis were presented for chemicals that promote or disrupt cellular signaling pathways. The developed analytical methods are based not only on receptor binding, but also on the following known molecular-level processes involved in signal transduction along signaling pathways, reconstituted in vitro or taken in part in living cells. The methods were discussed in relation to receptor binding assay and/or bioassay. Examples include: (1) Insulin signaling pathways; (1-i) Chemical selectivity of agonists for insulin signaling pathways based on agonist-induced phosphorylation of a target peptide; (1-ii) An SPR-based screening method for agonist selectivity for insulin signaling pathways based on the binding of phosphotyrosine to its specific binding protein; (1-iii) A fluorescent indicator for tyrosine phosphorylation-based insulin signaling pathways; (2) An optical method for evaluating ion selectivity for calcium signaling pathways in the cell; (3) Assay and screening of chemicals that disrupt cellular signaling pathways, potential endocrine disruptors in particular; (4) Protein conformational changes, and (5) A screening method for antigen-specific IgE using mast cells, based on intracellular calcium signaling.     

Deviations from the ΔI = 12 rule and nonlocal effect on the weak current-current interaction

Sum rules for deviations from the $\text{ΔI =}\text{1}\text{2}$ rule are discussed both for S- and P-wave hyperon decay amplitudes. The observed deviations for the P-wave decay amplitudes suggest that a nonlocal effect on the weak current-current interaction is not negligible.     

Structure elucidation and synthesis of a new anticoccidial substance isolated from streptomycesauranticolor

The structure elucidation and synthesis of WS 5995, produced by $\text{Streptomyces}$$\text{auranticolor}$, were described.     

Stereocontrol during the free‐radical polymerization of methacrylamides in the presence of Lewis acids

The effects of Lewis acids, that is, rare earth metal trifluoromethanesulfonates, on the free‐radical polymerization of N‐methylmethacrylamide (MMAM), N‐isopropylmethacrylamide (IPMAM), N‐tert‐butylmethacrylamide (tBMAM), N‐phenylmethacrylamide (PMAM), and methacrylamide were examined under various conditions. A catalytic amount of Yb(OSO₂CF₃)₃ significantly affected the stereochemistry during the radical polymerization. Polymerization solvents strongly influenced the effect of the Lewis acids. Methanol was the best solvent for increasing the isotactic specificity during the polymerization of MMAM and IPMAM, whereas tetrahydrofuran was more effective for the tBMAM and PMAM polymerizations. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1027–1033, 2003     

Preparation and chiral recognition ability of cellulose 3,5-dimethylphenylcarbamate immobilized on silica gel through radical polymerization

Polysaccharide-immobilized chiral stationary phases (CSPs) were prepared by the polymerization of cellulose 3,5-dimethylphenylcarbamate, having a polymerizable vinyl group, such as 4-vinylphenylcarbamate or 2-methacryloyloxyethylcarbamate, at the 6-position, with a vinyl monomer, such as styrene, isoprene, t-butyl acrylate, or t-butyl methacrylate, on silica gel under various conditions. Their chiral recognition abilities were then evaluated with high-performance liquid chromatography. The immobilized cellulose 3,5-dimethylphenylcarbamate remained on the silica gel even if washed with tetrahydrofuran, which could dissolve the cellulose derivative. The chiral recognition abilities of the immobilized CSPs were similar to those of the coated CSPs when the vinyl monomer content was low. The chiral recognition abilities of the obtained immobilized CSPs slightly depended on the vinyl monomers. The immobilization of the cellulose derivatives was more efficiently attained on the silica gel modified with a vinyl compound. The cellulose derivatives, randomly having a vinyl group at the 2-, 3-, or 6-position of the glucose unit, were prepared by a one-pot reaction. The immobilization efficiency of these derivatives was slightly lower than that of the derivative with the vinyl group at the 6-position. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3703–3712, 2003     

Silica gel-promoted synthesis of 3,4,5-triaryltetrahydro-1,4-thiazine derivatives from β,β′-dichloro sulfides and aromatic amines

A novel and efficient synthesis of 3,4,5-triaryltetrahydro-1,4-thiazine derivatives by treatment of β,β′-dichloro sulfides, 2:1 adducts of alkenes and sulfur dichloride, with aromatic amines in the presence of silica gel is described. The silica gel can be easily recovered and reused in up to four consecutive reactions without any significant decrease in product yield.