Van der Waals Gaps in Sm1+x Ba2−x Cu3O y and Their Effect on Superconductivity

We have used electron–positron annihilation to study superconducting cuprates Sm_1+x Ba_2–x Cu₃O _y . We have determined the average radii for oxygen ions in Sm_1+x Ba_2–x Cu₃O _y . Taking into account the ion coordinates and their radii, we have constructed a geometric model for the arrangement of copper and oxygen ions in CuO₂ layers in the [b, c] plane, responsible for the superconductivity. From these data, we have determined the length of the ionic/covalent bonds and the width of the interionic gaps. We have established the effect of the features of the atomic structure of Sm_1+x Ba_2–x Cu₃O _y on the superconducting transition temperature T _c and we have shown that T _c increases as X inceases.     

Representations ofD-forms

A criterion for module boundedness of a certain class of semihereditary rings — tensor algebras ofD-form — is given.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 44, No. 4, pp. 572–574, April, 1992.     

Representations of completely decomposable rings

A criterion is given for finiteness of the number of nonisomorphic nondecomposable representations for the completely decomposable orders over a complete local Dedekind ring which comprise an intersection of maximal orders.Translated from Matematicheskie Zametki, Vol. 3, No. 6, pp. 643–650, June, 1968.In conclusion the authors extend their utmost appreciation to all those participating in the seminar on representation theory at the Institute of Mathematics of the Academy of Sciences of the Ukrainian SSR for their continued interest and valuable suggestions toward the completion of this paper.     

Effect of Coulomb interaction of electrons on the intersubband emission lineshape in quantum wells

We have used perturbation theory for a many-particle system to analyze intersubband emission in quantum wells, taking into account Coulomb interaction of electrons. We obtained approximate analytical expressions for the shape factor for homogeneous broadening for intersubband transitions. We analyzed the effect of the excitation level and the temperature on the spectral lineshapes. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 642–647, September–October, 2007.