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A Wróblewska

Publications and source records attributed to A Wróblewska.

6 recordsLinked to original sources
PubMed2004

Origin of chemiluminescence accompanying the reaction of the 9-cyano-10-methylacridinium cation with hydrogen peroxide.

The 9-cyano-10-methylacridinium cation possesses an electrophilic center at the carbon atom in position (9) susceptible to the addition of anions. The addition of OOH(-) to this cation--in weakly acidic, neutral, or alkaline media--initiates processes leading to the formation of electronically excited 10-methyl-9-acridinone, which deactivates by light emission. The effect of changes in reactant concentrations and pH on emission decay with time, as well as other features of the accompanying chemiluminescence, were established. Calculations carried out at the semiempirical and density functional theory level demonstrated that initial addition of OOH(-) and subsequent processes lead either to the elimination of OCNH (in weakly acidic and neutral media) or OCN(-) (in alkaline media) and that their exothermicity is sufficiently high to generate electronically excited 10-methyl-9-acridinone. On the other hand, primary addition of OH(-) to C(9) in alkaline media initiates the conversion of the cation to the nonexcited 10-methyl-9-acridinone. This relatively rapid process influences to a substantial extent the intensity of the chemiluminescence. The prospects for the analytical application of 9-cyano-10-methylacridinium salts are briefly outlined.

Journal Article↗
PubMed2003

Spectral and acid-base features of 3,7-dihydroxy-2,8-diphenyl-4H,6H-pyrano[3,2-g]chromene-4,6-dione (diflavonol)--a potential probe for monitoring the properties of liquid phases.

Diflavonol is a molecule that can exist in neutral or anionic form and in several tautomeric forms in ground and excited states. Absorption and emission spectroscopy combined with theoretical calculations have shown that only one tautomer of neutral diflavonol exists in the ground state, but two exist in the excited state. In the latter case, one is the tautomer originating from the ground state tautomer, which exists in strongly protic solvents, the other is the phototautomer occurring in weakly protic or aprotic solvents as a result of the intramolecular transfer of one proton. The OH groups present in diflavonol and involved in weak intramolecular hydrogen bonds exhibit a proton-donating ability reflected by the experimental values of acidity constants or theoretical enthalpies and free energies of proton detachment. The electronically excited molecule is a relatively strong acid when it loses one proton. With increasing basicity of the medium, monoanionic and dianionic forms occur which exhibit spectral characteristics and an emission ability different from those of neutral diflavonol. These interesting features of diflavonol open up possibilities for the analytical use of the compound and its application as a spectral probe sensitive to the properties of liquid phases.

Journal Article↗
PubMed2002

Spatial genetic structure and clonal diversity of island populations of lady's slipper (Cypripedium calceolus) from the Biebrza National Park (northeast Poland).

Three populations of the rare and endangered plant species Cypripedium calceolus were included in a study of genetic diversity and spatial genetic structure in the Biebrza National Park, northeast Poland. Analysis of 11 allozyme loci indicate that the populations of this species contained high genetic variability (P = 45.5%, A= 1.73). On the other hand, the genetic differentiation (FST = 0.014, P < 0.05) among C. calceolus populations was very low when compared to other species with similar life history characteristics. The observed high rate of gene flow (Nm = 18) may suggest that the populations studied derived from each other in the recent past. Five polymorphic allozyme markers identified 109 multilocus genotypes in three populations and the majority of them (67%) were population-specific. One of the populations studied, characterized by particularly extensive vegetative reproduction, showed the lowest clonal diversity (G/N = 0.15) and heterozygosity (HO = 0.111) values and the highest FIS(0.380), when compared to other two populations (G/N = 0.26-0.27, HO= 0.166-178, FIS = 0.024-0.055). This may indicate that clonal reproduction has an important influence on the genetic structure of C. calceolus populations. The longevity of genets, the out-crossing breeding system and the presence of recruitment from seeds are factors maintaining genetic diversity in C. calceolus.

Biological Evolution↗
PubMed1995

Activity of exoglycosidases of the rat abdominal organs in untreated hemorrhagic shock.

Exoglycosidases catabolize glycoconjugates (proteoglycans, glycolipids and glycoproteins) at a rate depending on tissue and pathological changes. We determined exoglycosidase activity in successive sections of alimentary tract, spleen, liver and kidney of rats subjected to hemorrhagic shock. We found significant difference in exoglycosidase activity between alimentary tract segments in control animals and no significant changes in homologous tissues of the shocked rats comparing with control.

Animals↗