Active thionium species mediated functionalization at the 2α-position of indole derivatives

A combination of dimethyl sulfoxide (DMSO) and trifluoroacetic anhydride (TFAA) mediates functionalization at the 2α-position of indole derivatives. Carbon and heteroatom nucleophiles were directly introduced via a one-pot procedure in excellent yields.     

Class number parity for cyclotomic fields

We give a simple criterion for the parity of the class number of the cyclotomic field.

     

Synthesis and crosslinking reaction of poly(hydroxyurethane) bearing a secondary amine structure in the main chain

This article describes the polyaddition of bifunctional five‐membered cyclic carbonates and diethylenetriamine. The polyaddition proceeded via the selective addition of the primary amino group to the cyclic carbonates to give poly(hydroxyurethane)s bearing a secondary amine structure in the main chain. The resulting poly (hydroxyurethane) having a secondary amine structure was crosslinked by a reaction with a bifunctional dithiocarbonate to give a networked poly(hydroxyurethane–mercaptothiourethane). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5899–5905, 2005     

Effects of a magnetic field on triplet-triplet annihilation in a Pt-phthalocyanine single crystal at 4.2 K

Mutual annihilation of triplet excitons in Pt-phthalocyanine single crystal at 4.2 K has been studied under magnetic fields of up to 100 kG through the measurement of the phosphorescence decay by Q-switched ruby laser excitation. The maximum annihilation rate γ which is larger than that of zero magnetic field by 40–50% is obtained at magnetic fields of 30–40 kG. The annihilation rate γ is of the order of 10⁻¹² cm³/s.     

Photoluminescence of cis- and trans-polyacetylene

The emission intensity in cis-(CH)_χ increases a little and the emission peak shifts a little to shorter wavelength with increasing temperature, which can be interpreted by the distribution of several emission centers in energy. Photoluminescence is also observed in trans-(CH)_χ at around 1.03 μm for the first time.     

Hadroproduction of heavy quark flavors in QCD

Within the framework of perturbative QCD, we investigate the hadroproduction of charmed particles via two-gluon as well as quark-pair annihilation. The total production cross section is found to be sensitive to the choice of the scale parameter Q² and in general not free from non-perturbative effects. Charmed-particle production in the high-p_T region is also studied.     

Numerical study of localization in Anderson model for disordered systems

The localization properties in the Anderson model of two dimensional square lattices are investigated numerically. Pretty large lattices composed of 10⁴ (= 100 × 100) sites are dealt with, and the overall behaviors of the eigenvectors near the band center are directly examined. Fairly sharp transition and the exponentially decaying localized states are visualized.     

A self-consistent cluster theory of amorphous materials

A cluster method for the electronic structure of amorphous materials is presented with an application to amorphous diamond. Eight-atom cluster model gives a pseudogap in the density of states.