Deficiently extremal Gorenstein algebras

The aim of this article is to study the homological properties of deficiently extremal Gorenstein algebras. We prove that if R/I is an odd deficiently extremal Gorenstein algebra with pure minimal free resolution, then the codimension of R/I must be odd. As an application, the structure of pure minimal free resolution of a nearly extremal Gorenstein algebra is obtained.     

Curing and thermal behaviour of DGEBA using mixture of biuret and 4,4′-diaminodiphenylsulfone

Curing behaviour of DGEBA was investigated in the presence of varying molar ratio of biuret and 4,4′-diaminodiphenylsulfone (DDS) by means of Differential scanning calorimetery. The multiple heating rate method (5, 10, 15 and 20 °C min⁻¹) was used to study the curing behaviour of epoxy resins. The peak exotherm temperature was found to be dependent on the heating rates, structure of biuret as well as on the ratios of biuret:DDS used. Ozawa method was used for calculating the activation energy of curing reaction. The thermal stability of the isothermally cured resins was evaluated by recording the thermogravimetric traces in nitrogen atmosphere. All the samples were stable up to 330 °C.     

On subgroups and factor groups of GL(n, q) acting on spreads with the same characteristic

Let π^l_∞ be an affine translation plane of order q^r with GF(q) in its kern. Suppose G is a subgroup of the translation complement of π^l_∞ which leaves invariant a set Δ of q + 1 slopes and acts transitively on l_∞?Δ. We study the situation when G≌SL(n, q) or PSL(n, q).We show that if G|Δ = identity, then π^l_∞ is a Hall plane, a Lorimer-Rahilly plane (LR-16) or a Johnson-Walker plane (JW-16). Moreover, if n?3, then G fixes Δ elementwise and π^l_∞ is LR-16 or JW-16.