Invariance of selfinjective algebras of quasitilted type under stable equivalences

We prove that the class of finite dimensional selfinjective algebras over a field which admit Galois coverings by the repetitive algebras of the quasitilted algebras, with Galois groups generated by compositions of the Nakayama automorphisms with strictly positive automorphisms, is invariant under stable and derived equivalences. Dedicated to Claus Michael Ringel on the occasion of his sixtieth birthday     

On the relaxation of trapped electrons in glassy hydrocarbons irradiated at 4 K

In contrast to previous reports e^?_t in 3MHx produced at 4 K shows trap relaxation when warmed to 77 K. The relaxation in 3 MHx and 3MP occurs without loss of e^?_t, and results in an increase in ?_max as well as a shift of λ_max.     

Synthesis and characterization of poly[4-(4-hydroxyphenoxy) benzoic acid]

Poly[4-(4-hydroxyphenoxy) benzoic acid] was prepared by the bulk polycondensation of 4-(4-acetoxyphenoxy) benzoic acid. Polycondensation was conducted at 350°C for 3 h under a reduced pressure of 0.1 mmHg and gave a polymer with X?n of 255. The polymer was characterized by elemental analysis, IR spectroscopy, differential scanning calorimetry, and wide-angle X-ray measurement. The crystal/nematic and nematic/isotropic phase transition temperatures of polymer, which depend on the molecular weight, were observed at about 300°C and 410°C, respectively. The polymers with low molecular weights showed nematic textures above 300°C. This nematic/isotropic phase transition temperature is lower than that of poly (4-hydroxybenzoic acid). This thermal behavior of polymer comes from ether units, which increase the flexibility (the rotation or torsion of skeletal bonds) of the polymer chain. © 1994 John Wiley & Sons, Inc.     

A new route to 1-phenylnaphthalenes by cycloaddition: a simple and selective synthesis of some naphthalene lignan lactones

2-(2-Dithianyl)benzhydrols ($\text{2}$ a-c) undergo facile cycloaddition reaction with maleic anhydride under thermal conditions to give 1-phenyl-naphthalenes ($\text{7}$ a-c) in one step. The naphthalenes ($\text{7}$ a-c) have been converted into the naphthalene lignan lactones, ($\text{9}$ a-c) and ($\text{10}$ a-c).     

Site-specific alkylation of tetra-alkylpyrroles

Intramolecular cyclisation of the trifluoromethanesulphonate esters of the β-(4-hydroxy-n-butyl)-pyrroles (5a) and (5b) in each case yields a mixture of the α- and β-alkylated products whereas exclusive β-alkylation is observed for the β-(5-hydroxy-n-pentyl)-pyrrole (5c).