In this paper further characterizations of Hermitian, normal and EP operators on Hilbert spaces are established. Thus the recent results of O. M. Baksalary and G. Trenkler (Linear Multilin. Algebra, to appear) are extended to the infinite dimensional setting with proofs based on operator matrices.

A series of N- and N,N-dialkyl-S-alkylthiolcarbamates were synthesized by the rearrangement of N- and N,N-dialkyl-O-alkylthioncarbamates in the presence of diethyl sulfate. The synthesis of some compounds without catalyst was also performed. The compounds were identified by IR, 1H NMR and MS spectroscopic methods. The starting thioncabamates were obtained from the corresponding xanthogenacetates and amines and their structures were also confirmed by IR, 1H NMR and MS data. Some of the thiolcarbamates were characterized for the first time in the literature

We prove some results for the group inverse of elements in a unital ring. Thus, some results from (C. Deng, Electronic J. Linear Algebra 31 (2016)) are extended to more general settings.

The transformations of the cardiac glycosides lanatoside A, B and C can be performed enzymatically with digilanidase (P-glucosidase) and acetyl-esterase from plant, animal or microbialIn this paper the transformation with enzymes from plant sources (barleycorns, hemp-and flax-seed) as well as with a comercial preparation of biocellulase (Biocon GmbH Kolbemoor) was investigated, wich has not been used for this purpose yet. The enzyme preparations used were prepared by our procedure? From the investigation of the degree and products of enzymatic hydrolysis of la in aqueous suspension (37 O ; enzyme preparation: substrate = 8: 1 ; pH 6.8-7.0; 48 h) it was established that the selective biotransformation of la to acetyl-digitoxine (lb) and digitoxine (lc) occured with the enzyme preparation from flax-seed and the comercial biocellulase, respectivelly. The other two enzyme preparations investigated had significantly less activity (three to four times) and were not selective, i. e. a mixture of lb and lc was obtained (table 1).The kinetic investigation of the enzymatic hydrolysis and the change of the enzyme activity during the hydrolysis under optimum conditions showed that the maximum degrees of hydrolysis of la with the enzyme preparation from flax seed and with biocellulase (65 % and 68 %, respectivelly) were obtained after 48 h.