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W Piasecki

Publications and source records attributed to W Piasecki.

12 recordsLinked to original sources
PubMed2006

Systematic position of copepods of the genus Achtheres (Crustacea: Copepoda: Siphonostomatoida) parasitizing perch, Perca fluviatilis L., and zander, Sander lucioperca (L.).

Parasitic copepods of the genus Achtheres commonly infect perch, Perca fluviatilis, and zander, Sander lucioperca, in Europe. The aim of this study was to verify the specific identity of these copepods. The parasites were examined morphologically, biometrically and genetically. Statistical processing of the biometrical data was based on both empirical measurements and transformed data related to total length and genital trunk width. Principal component analysis was applied to both sets of data. DNA of both parasite 'forms' was amplified using two sets of primers (EU5.8S+EU18S and 18SF1+28SR) and the products were subjected to restriction fragment length polymorphism (RFLP). Morphological differences were found in the overall shape of the copepod bodies as well as in the details of the armament of some appendages. The morphometric study emphasized the importance of second maxillae and genital process as the variables most distinctly distinguishing the two 'forms'. The two 'forms' of Achtheres differed in the DNA sequence amplified by one set of primers. RFLP revealed even more extensive differences between these two copepods. We concluded that the copepods parasitizing perch should be referred to as Achtheres percarum von Nordmann, 1832, whereas a long-forgotten name, A. sandrae Gadd, 1901, should be applied to the copepods from zander.

Animal Structures↗
PubMed2002

Calorimetric effects accompanying ion adsorption at the charged metal oxide/electrolyte interfaces: effects of the correlations between the binding-to-surface energies of various surface complexes.

As has been shown in our earlier publications, a theoretical description of ion adsorption at the real, energetically heterogeneous oxide/electrolyte interfaces, involves necessary assumption about the correlations between the adsorption energies of the various surface complexes formed at this interface. So far, only two extreme models have been considered in such theoretical descriptions: one model assuming that high correlations exist, and the other assuming that practically no correlations exist. The purpose of this paper is to develop yet another description based on a model assuming that some partial correlations exist between the adsorption energies of the various surface complexes. The other purpose of this publication is to test these three models by analysing some experimental data reported so far in literature. Such data sets must include necessary information about the enthalpic effects accompanying ion adsorption. This is because enthalpic effects are known to be more sensitive to the mechanistic models underlying a theoretical description of adsorption systems. With such requirements in mind, we have selected three adsorption systems: Al2O3/NaCl, TiO2/NaCl and silica/NaCl, for our analysis. Our theoretical-numerical analysis of the behaviour of these adsorption systems suggests that either none or partial correlations exist between the adsorption energies of the various surface complexes. However, that analysis also shows, that the present accuracy of the experimental data does not allow us to draw more elaborate conclusions.

Journal Article↗
PubMed1998

A rectangular loop-gap resonator for EPR studies of aqueous samples.

A new rectangular geometry of the loop-gap resonator for the use with a flat cell has been developed. Maxwell's equations for the resonators with two, four, six, and eight gaps have been solved assuming the existence of only the magnetic z-component. The formulas obtained were numerically solved for the electric and magnetic field distributions over the cross-sections of the resonators. The presence of a nodal plane for the electric field in the center of the resonator allows the use of a flat cell instead of a capillary for EPR measurements. Using the field distributions obtained, the quality factor and EPR signal amplitude for various shapes and gap numbers for the resonators containing a flat cell filled with water were examined numerically. This allowed finding the geometry that yields the maximum EPR signal intensity. Several X-band resonators were built in order to verify the results obtained theoretically. The experiments confirmed the ability of a novel resonant structure to accommodate a flat cell filled with an aqueous sample. It has been found that the optimum aqueous sample volume for the X-band rectangular loop-gap resonator equals 16 mm3. For a saturable aqueous sample this gives a fourfold improvement in the S/N ratio over the circular 1 mm i.d. loop-gap resonator equipped with 0.6 mm i.d. capillary.

Electron Spin Resonance Spectroscopy↗
PubMed1997

New model of charged molecule redistribution induced in spherical vesicles by direct current electric field.

A new electrophoresis model of charged components in a spherical phospholipid vesicle is proposed. In the new model the effective local tangential electric field is a result of the uniform external electric field modified by the electric field of redistributed charges. The modification is calculated on the basis of the Gouy-Chapman surface potential theory. Numerical calculations of steady-state distribution of charged molecules and the transmembrane potential are performed. The results show significant difference from the old, simplified model that neglects modification of the external electric field caused by redistributed charges.

Chemical Phenomena↗
PubMed1994

Infection seasonality of Tracheliastes maculatus Kollar, 1835 (Copepoda, Siphonostomatoida, Lernaeopodidae) in the warm-water canal of "Dolna Odra" power plant.

Freshwater bream Abramis brama inhabiting warm-water discharge canal of the "Dolna Odra" Power Plant (Poland) were surveyed within 1983-1986 for their copepod parasites Tracheliastes maculatus. A total of 812 bream was studied and 561 females and 7 males of the parasite were recovered. The overall prevalence (for the whole survey) was 23.3% and the overall abundance was 0.69. T. maculatus were prevalent and abundant in winter while in summer they were encountered sporadically. The seasonality of the parasite exhibited consistent pattern within the studied period and it showed no signs of rise beyond the natural balance limits.

Animals↗
PubMed1993

Cystic fibrosis--V. Does cystic fibrosis alter the values of dynamic parameters of erythrocyte membrane ghosts?

1. The dynamic properties of erythrocyte membranes in CF children have been investigated by means of fluorescence and ESR techniques. 2. It has been revealed that the apparent distance separating the membrane protein tryptophan and bound 1-anilino-8-naphthalenesulphonate (ANS) molecules is decreased in CF children which results in a significant increase of the maximum energy transfer efficiency. 3. The slight increase in the ratio hw/hs of maleimide bound to membrane protein-SH groups of erythrocytes in cystic fibrosis may ensue the lowered membrane protein immobilization in the plane of lipid bilayer, especially at the intrinsic, more slowly reacting thiol groups.

Anilino Naphthalenesulfonates↗
PubMed1992

The association between erythrocyte internal viscosity, protein non-enzymatic glycosylation and erythrocyte membrane dynamic properties in juvenile diabetes mellitus.

The association of intracellular viscosity of red blood cells and the dynamic properties of erythrocyte membranes in children suffering from diabetes has been investigated by means of ESR spectroscopy. It has been revealed that the slight decrease in the ratio hw/hs of maleimide bound to membrane protein-SH groups of erythrocytes in diabetes may ensue from the enhanced membrane protein immobilization in the plane of lipid bilayer. These alterations were accompanied by a corresponding increase in the relative rotational correlation time (tau c) of iodoacetamide spin label, thus suggesting that the conformational changes in membrane proteins may occur at both the intrinsic and more exposed thiol groups. The membranes of diabetic red blood cells were more glycosylated than those of relevant controls, and the extent of glycosylation was found to correlate significantly with h + 1/h0 and tau c (r = -0.652, P < 0.01 and r = 0.609, P < 0.01). Further, the conformational alterations in erythrocyte membranes from diabetic subjects were accompanied by a significant increase in the mobility parameter (h + 1/h0) of haemoglobin molecules in diabetic erythrocytes. The latter changes correlated well with the enhanced intracellular viscosity of diabetic red blood cells and the level of glycosylated haemoglobin. We conclude that the alterations in membrane lipid-protein interactions together with the increased glycosylation-derived internal viscosity may consequently imply altered viscoelastic properties of erythrocyte membranes and, underlying the impaired deformability of red blood cells in the diabetic state, contribute to the development of late diabetic sequelae.

Adolescent↗