Interactions between bovine serum albumin and various clays including pure clay minerals and bentonite were studied with the aim to describe the interaction process. The adsorption of albumin on the clays is strongly affected by the behavior of clays in the aquatic environment (hydrolysis and release of cations). A sufficient amount of albumin was adsorbed on the acid-activated montmorillonite K10 (0.067 mg mg⁻¹) and on the illite–smectite (0.086 mg mg⁻¹). These clay minerals do not strongly affect the sorption solution parameters such as pH value and content of cations. Practically no adsorption was observed on the bentonite and vermiculite. Bentonite and vermiculite are subject to stronger interactions with water which cause the increase of pH value of the sorption solution and release of cations to the solution and thus they cause conformational changes of albumin, which was confirmed by circular dichroism measurements. Obtained results were confirmed by infrared spectroscopy and thermal analysis as well. Interaction of studied materials with bovine serum albumin causes the reduction of particle size in the case of all studied clays except vermiculite. Albumin probably attacks the clay structure during the adsorption, which causes the decrease of particle size. The presented work contributes to the knowledge about interaction of bovine serum albumin with clays in the field of influence of physico-chemical behaviour of clays in the solution on the interaction with albumin.

Porous carbons, originated from resorcinol-formaldehyde (RF) gels, show high application potential. However, the kinetics and mechanism of RF condensation are still not well described. In this work, different methods (dynamic light scattering–DLS, Fourier transform infrared spectroscopy–FTIR, low field ¹H nuclear magnetic resonance relaxometry–¹H-NMR, and differential scanning calorimetry–DSC) were used to follow the isothermal RF condensation of mixtures varying in catalyst content (Na₂CO₃) and reactant concentration. The applicability and results obtained by the methods used differ significantly. The changes in functional groups can be followed by FTIR only at very early stages of the reaction. DLS enables the estimate of the growth of particles in reaction solution, but only before the solution becomes more viscous. Following the relaxation of ¹H nuclei in water during RF condensation brings a different view on the system—this technique follows the properties of the present water that is gradually captured in polymeric gel. From this side, the process behaves similarly to the nucleation reaction, which is in contradiction to the n-order mechanism confirmed by other techniques. The widest range of applicability was found for DSC measurement of the freezing/melting behavior of the reaction mixture, which is possible to use without any limitations until full solidification. Furthermore, this approach enables us to follow the gradual formation and development of the gel through the intermediate undergoing glass transition.

Příspěvek se zabývá problematikou znečištění říčních (dnových) sedimentů v povodí řeky Odry, které se nachází na jednom z nejvíce antropogenně znečištěném území

Raw and torrefied faeces from four zoo animals (giraffe, deer, camel, reindeer) and a sample of zebra manure pellets were studied to assess their energy potential using combustion calorimetry and thermoanalytical (TG/DTA) methods. Marked differences (ca 12%) in the torrefaction yield of the faeces were found depending on the animal species. Using the standard deviation of torrefaction yield, the heterogeneity of the droppings within one animal species was estimated to be up to 4%. Torrefied faeces demonstrated an increase in higher heating values by about 30% compared to raw samples. The differences between the higher heating values of samples torrefied at 300 °C and 250 °C were found to be relatively insignificant, both leading to completely comparable values of the energy densification ratio. According to elemental composition, higher heating value and combustion characteristics, torrefied faeces proved to be quite comparable to these parameters of lignite.