Tensor Products and Preservation of Weighted Limits,for S-Posets

We prove that the functor of tensor multiplication by a right S-poset (S is a pomonoid) preserves all small weighted limits if and only if this S-poset is cyclic and projective. We also show that this functor preserves all finite pie-limits if and only if the S-poset is a filtered colimit of S-posets isomorphic to S _S .     

On Morita Equivalence of Partially Ordered Monoids

We show that there is one-to-one correspondence between certain algebraically and categorically defined subobjects, congruences and admissible preorders of S-posets. Using preservation properties of Pos-equivalence functors between Pos-categories we deduce that if S and T are Morita equivalent partially ordered monoids and F:Pos _S →Pos _T is a Pos-equivalence functor then an S-poset A _S and the T-poset F(A _S ) have isomorphic lattices of (regular, downwards closed) subobjects, congruences and admissible preorders. We also prove that if A _S has some flatness property then F(A _S ) has the same property.     

Wreath Product of Set-Valued Functors and Tensor Multiplication

Considering the wreath product functor $G wr H:{\cal A} wr^G{\cal B} \rightarrow \SET$ of functors $G: {\cal A}\rightarrow \SET$ and $H: {\cal B}\rightarrow \SET$ over small categories $ {\cal A}$ and $ {\cal B}$, we prove that if tensor multiplication by the functor $G\wrr H$ preserves $ {\cal D}$-limits, where ${\cal D}$ is a small category, then tensor multiplication by $G$ preserves ${\cal D}$-limits, and if tensor multiplication by the functor $G wr H$ preserves ${\cal D}$-limits of representables then tensor multiplications by $G$ and $H$ preserve $ {\cal D}$-limits of representables. We also study flatness and pullback flatness of the wreath product of set-valued functors.     

When Torsion Free Acts are Principally Weakly Flat

A necessary and sufficient condition for principal weak flatness of all right torsion free acts over a monoid is found. It is shown that the corresponding class of monoids is a proper subclass of left PP monoids.     

Strong Morita equivalence of semigroups with local units

In this paper we study Morita contexts for semigroups. We prove a Rees matrix cover connection between strongly Morita equivalent semigroups and investigate how the existence of a unitary Morita semigroup over a given semigroup is related to the existence of a ‘good’ Rees matrix cover of this semigroup.     

Morita invariants for semigroups with local units

In this paper we study Morita invariants for strongly Morita equivalent semigroups with local units of various kinds. Among others we prove that, under a certain condition of this kind, congruence lattices are preserved by strong Morita equivalence.     

On Descent Theory for Monoid Actions

We give some sufficient conditions for a monoid homomorphism to be an effective descent morphism.     

Thermomechanical and adhesive properties of radiation-modified polymer composites for thermosetting products

Gamma-irradiated blends of polyethylene (PE) with ethylene-propylene-diene copolymer (EPDM) and a thermotropic liquid-crystalline polymer (LCP) are investigated at absorbed radiation doses not exceeding 150 kGy (10 kGy=1 Mrad). The temperature dependences of elastic moduli, tension diagrams at a temperature above the melting point of the crystalline phase of PE, and long-term strain recovery curves for oriented test specimens are presented. The kinetics of thermal relaxation and shrinkage stresses in previously oriented composite specimens upon their heating and cooling is investigated. Data on the influence of LCP additions on the adhesive interaction of the compositions with steel are obtained. The peculiarities of thermomechanical and adhesion properties of these composites are discussed taking into account the morphologic and calorimetric data obtained. Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 3, pp. 379–394, May–June, 2000.