Syntheses of anthraquinone capped hairpin DNAs and electrochemical redox responses from their self-assembled monolayers on gold electrode

An anthraquinone (AQ) based DNA linker and hairpin-forming DNAs linked by the AQ linker with variable A-T base pairs were synthesized for the investigation of electron transfer through double helical DNA (DNA-ET) in self-assembled monolayers (SAMs). The spectroscopic analysis of absorption spectra indicated that the AQ of the hairpin DNA stacked with adjacent A-T base pair. Electrochemical redox response due to the AQ was observed from the hairpin DNA immobilized on gold electrode, thus the hairpin DNA is suitable for the investigation of DNA-ET in SAMs.     

Controlling 3(10)-helix and alpha-helix of short peptides in the solid state

L-Leu hexapeptide containing alpha-aminoisobutyric acid (Aib) forms a right-handed (P) 3(10)-helix, whereas that containing cyclic alpha,alpha-disubstituted amino acid Ac(5)c(dOM) assumes a right-handed (P) alpha-helix in the solid state.     

Solid-phase combinatorial syntheses of mesomorphic 4-alkoxyphenyl 4-alkoxybenzoylaminobenzoates

Eighteen two-ring and 100 three-ring benzenoid amides were synthesised using a solid-phase combinatorial method involving acylation or benzoylation and palladium(0)-catalysed carbonylation of a secondary amine, obtained by the reductive amination of 4-iodoaniline and a backbone amide linker. The purity of the products obtained was high enough for investigation of their thermal properties. All the three-ring derivatives were shown to be mesomorphic, but the two-ring derivatives were not. The mesomorphic behaviour and the transition temperatures of the three-ring derivatives were virtually identical to those of samples obtained by liquid-phase synthesis and purified by column chromatography and recrystallisation.     

Numerical analysis of oscillatory Couette flow of a rarefied gas on the basis of the linearized Boltzmann equation for a hard sphere molecular gas

The time-dependent motion of a rarefied gas between two parallel planes caused by an oscillatory motion of the plane is studied based on the linearized Boltzmann equation for a hard sphere molecular gas. With the aid of a deterministic numerical method, an accurate numerical analysis is carried out for a wide range of gas rarfaction and oscillatory frequency. The detailed data of the shear stress acting on the planes is provided in a complete form for a wide range of the parameters. The transition of the solution from low to high frequencies under various degrees of gas rarfaction is discussed.     

The uniqueness of the integrated density of states for the Schrödinger operators with magnetic fields

The integrated density of states (IDS) for the Schr?dinger operators is defined in two ways: by using the counting function of eigenvalues of the operator restricted to bounded regions with appropriate boundary conditions or by using the spectral projection of the whole space operator. A sufficient condition for the coincidence of the two definitions above is given. Moreover, a sufficient condition for the coincidence of the IDS for the Dirichlet boundary conditions and the IDS for the Neumann boundary conditions is given. The proof is based only on the fundamental items in functional analysis, such as the min-max principle, etc. Received August 26, 1999; in final form February 21, 2000 / Published online February 5, 2001     

Elucidation of mechanism for living radical polymerization of styrene with N,N-diethyldithiocarbamate derivatives as iniferters by the use of spin trapping technique

The photodissociation of several N,N-diethyldithiocarbamate derivatives (RDC), i.e., benzyl, 1-phenylethyl, 2-phenylethyl, n-butyl, sec-, and tert-butyl N,N-diethyldithiocarbamates, was investigated by the spin trapping technique to elucidate the polymerization mechanism of styrene (St) with RDC as iniferters. The scission of RDC occured at two different C? S bonds depending on the structure of the alkyl groups of RDC and the cleavage manner was dominated by both resonance and steric effects. It has been confirmed that RDC generating an N,N-diethyldithiocarbamyl radical acts as an effective iniferter and induces the living radical polymerization of St in homogeneous system. The polymerizations of St with tetraethylthiuram disulfide and p-xylylene bis(N,N-diethyldithiocarbamate) were also discussed on the basis of the results of the spin trapping for RDC as the model compounds of the poly(St) chain ends. © 1994 John Wiley & Sons, Inc.     

Preparation of O-1∼C-6 and O-7∼C-14 fragments of colletodiol

(5S,2E)-5-Tetrahydropyranyloxy-2-hexenoic acid and p-toluenesulfonylethyl (4R,5R,7R,2E)-7-hydroxy-4,5-dimethylmethylenedioxy-2-octenoate were prepared from ethyl acetoacetate and D-glucose, respectively.