Interaction of Carcinogenic Chromium(VI) Oxide,CrO3, with Main Nonenzymatic Cellular Reductants at Physiological Conditions. Electronic Spectra and Magnetic Studies

The interaction of CrO₃ with ascorbic acid, glutathione and cysteine at physiological conditions (pH=7.4, t=37°C) was investigated using spectral (diffuse reflectance spectra) and magnetic methods. The obtained powders appeared to be Cr(III) complexes of the [Cr(A, B)(H₂O)_x]^n- type, where A, B are organic ligands (A-ascorbic acid, B-glutathione or cysteine). The spectral resolution of the bands enhanced with a digital filter method revealed the lowering symmetry effect in the chromium(III) coordination sphere. The comparison of the results obtained for K₂CrO₄ with these studied in the present paper was made.     

Physicochemical properties and thermal behavior of nitrocellulose granules with eutectic mixtures of stabilizers

Journal of Thermal Analysis and Calorimetry - Examinations of two-component mixtures, namely: triphenylamine?+?centralite I (TPA?+?CI) and...     

Influence of barium oxide on glass-forming ability and glass stability of the tellurite–phosphate oxide glasses

Journal of Thermal Analysis and Calorimetry - The effect of BaO content on the glass-forming ability, glass stability and structure of tellurite–phosphate oxide glasses in the...     

Existence and stability of oscillating solutions for a class of delay differential equations

In this paper we study a Hopf bifurcation for a general class of simple delay differential equations with a term that can describe a treatment. Conditions guaranteeing appearance of the Hopf bifurcation as well as stability of arising periodic orbits are proved. Applications of proved theorems to a general version of the logistic equation are presented.     

On families of invariant lines of a Brouwer homeomorphism

ABSTRACT

We present properties of equivalence classes of the codivergency relation defined for a Brouwer homeomorphism for which there exists a family of invariant pairwise disjoint lines covering the plane. In particular, using the codivergency relation we describe the sets of regular and irregular points for such Brouwer homeomorphisms. Moreover, we show that under this assumption the interior of each equivalence class of this relation is invariant and simply connected.     

Copper removal by carbon nanomaterials bearing cyclam-functionalized silica

The synthesis of metal (Fe, Co, Ni)-encapsulated carbon nanomaterials coated with cyclam-bonded silica has been described. The organic layer was identified by Fourier transform infrared spectroscopy and elemental analysis. The functionalized magnetic nanomaterials were employed to extract the divalent cations: copper, calcium, cobalt, manganese and nickel from aqueous solutions. Their adsorption capacities were studied by the batch procedure. The concentration of cations extracted was determined by inductively coupled plasma mass spectrometry. Influence of different parameters viz. pH, amount of the compound studied, contact time, on the cation extraction was investigated. Under optimum conditions copper extraction was significantly more efficient when compared with other coexisting ions.      

Selectivity in normal-phase liquid chromatography with binary mobile phase

A simple theoretical approach to normal-phase liquid chromatography with binary mobile phase is presented. In the model used the driving force for the retention is competitive adsorption of solutes and both solvents. A new expression for the separation factor is proposed and discussed. An influence of different parameters on the selectivity is shown. The theoretical concepts are illustrated by the selected experimental data.     

Influence of solution pH on stability of aluminum oxide suspension in presence of polyacrylic acid

The effect of solution pH and molecular weight of polyacrylic acid (PAA) on its adsorption as well as on stabilization-floculation properties of the colloidal Al₂O₃ and electrolyte solution systems was studied. The measurements showed that at pH = 6, the presence of the polymer of molecular weight 2?000 and 240?000 does not change stability of Al₂O₃ suspension. However at pH =3 and 9 the effect of polyacrylic acid is significant. At pH = 3 it creates destabilization of the suspension while at pH = 9 PAA it improves significantly the stability of Al₂O₃. It was shown that the increase in solution pH affects conformation of adsorbed macromolecules which causes the decrease in PAA adsorbed amount and thickness of polymer adsorption layer. By comparing the values of diffusion layer and surface charges, main effects responsible for the decrease in surface charge and ζ potential of the solid in the presence of the polymer as well as suspension stability were determined.     

Application of DLLME to Isolation and Concentration of Non-Steroidal Anti-Inflammatory Drugs in Environmental Water Samples

Dispersive liquid–liquid microextraction (DLLME) coupled with liquid chromatography-tandem mass spectrometry detection was applied for determination of selected anti-inflammatory pharmaceuticals: ibuprofen, ketoprofen, naproxen and diclofenac. Development of DLLME procedure included optimisation of several important parameters such as kind and volume of extracting and dispersive solvents as well as sample pH. Under optimised conditions a two-step extraction with sonication was used. Chloroform was applied as the extracting and acetone as dispersing solvent. Calibration curves ranges were 1–500 μg L^?1 for naproxen and ibuprofen and 0.25–500 μg L^?1 for ketoprofen and diclofenac with correlation coefficients at least 0.997. Limits of quantitation were from 0.5 to 10 ng L^?1. The developed analytical method was employed for determination of ibubrofen, ketoprofen, naproxen and diclofenac in river and tap water samples. The results showed that DLLME is a simple, rapid and sensitive analytical technique for the pre-concentration of trace amounts of pharmaceuticals in environmental water samples.