Volume 67, Issue 3

We focused on the determination of biologically active secondary metabolites in wild hops over the course of the vegetation period in four selected sites in Piešťany. Hop was collected in four collection periods in 2010. The objects of research were the leaves of male and female plants, and female cones. Analysis of the extracts from wild hop confirmed differences in total content of polyphenols, flavonoids between the localities and in the growing seasons over the vegetation period. The extracts from leaves from the first harvest in localities “gSládkovičova” and the river Vah showed higher levels of polyphenols (4.91–6.93 mg g−1 of dry mass), flavonoids (2.28–2.99 mg g−1 of dry mass) than the extracts from cones collected at the end of the vegetation period (polyphenols 3.63–5.33 mg g−1 of dry mass, flavonoids 1.86–2.16 mg g−1 of dry mass). The extracts from leaves from the first harvest from the “tennis court” site showed lower values of polyphenols and flavonoids. Our findings were that the leaves from the first harvest at the beginning of the growing season contained higher amounts of the secondary metabolites investigated than the cones at the end of the growing season. The content of α-bitter acids in wild hop cones ranged from 1.64 % to 2.91 %, in leaves from 0.11 % to 0.99%. Concentration of β-bitter acids in cones varied from 1.63 % to 1.93 % and in leaves from 0.02 % to 0.61 %.

The sorption of thioflavine T (TT) and malachite green (MG) cationic synthetic dyes on dried biomass of green microalga (Chlorella pyrenoidosa) immobilised in polyurethane foam under continuous column systems conditions using spectrophotometric methods of detection was investigated. Data characterising the sorption of TT and MG on microalgal biomass immobilised in polyurethane foam in a column system from single (C 0 = 25 μmol dm−3) or binary equimolar (C 0 = 25 μmol dm−3) dye solutions in the form of breakthrough curves were well described by the Thomas (R 2 = 0.994–0.912), Yoon-Nelson (R 2 = 0.994–0.911), and Clark (R 2 = 0.993–0.911) models. Useful parameters characterising the sorption column system were obtained from these mathematical models. The Thomas model, in particular, provided the Q max (maximal sorption capacity in μmol g−1) parameter for characterisation of biosorbent and also for evaluation of competitive effects in the TT and MG dyes sorption. For the purposes of biomass regeneration, a one-step desorption of the dyes studied from the microalgal biomass in batch and continuous column systems was performed. Efficiency of TT desorption from microalgal biomass increased in the order: deionised H2O (50.7 %), 99.5 vol. % 1,4-dioxane (67 %), 20 mmol dm−3 NiCl2 (83 %), 96 vol. % ethanol (85 %), 0.1 mol dm−3 HCl (89 %), 1 mol dm−3 acetic acid (89 %). In the case of MG, the desorption efficiency increased in the order: deionised H2O (13 %), 20 mmol dm−3 NiCl2 (50 %), 0.1 mol dm−3 HCl (91 %), 99.5 vol. % 1,4-dioxane (94 %), 1 mol dm−3 acetic acid (99 %), 96 vol. % ethanol (> 99 %). The presence of carboxyl, phosphoryl, amino, and hydroxyl groups, the important functional groups for sorption of cationic xenobiotics, was also confirmed on the algae biomass surface by potentiometric titration and ProtoFit modelling software. The data obtained showed that the dried immobilised algae biomass could be used as a sorbent for removing toxic xenobiotics from liquid wastewaters or contaminated waters and also presenting the possibilities of mathematical modelling of sorption processes in continuous column systems in order to obtain important parameters for use in practice.

Sludges produced in huge amounts by wastewater treatment plants (WWTP) display high fertility properties; however, the presence of heavy metals restricts their use for agricultural purposes. Sorption capacity of sludge is generally much higher and it can also be considered as a cheap sorbent of heavy metals. The paper describes cobalt sorption by dried activated sludge (DAS) obtained from the aerobic phase of a WWTP. DAS was characterized by FT-IR spectroscopy, cation exchange capacity (CEC), and atomic absorption spectrometry (AAS) analysis. Sorption capacity of DAS (Q eq) increased with the initial concentration (C 0) of Co2+ (CoCl2) within the range from 100 μmol g−1 to 4000 μmol g−1, reaching 15 μmol g−1 and 200 μmol g−1, respectively. The maximum uptake capacity (Q max) at pH 6.0 calculated from the Langmuir isotherm model was (256 ± 9) μmol g−1 for Co2+ ions. Obtained Q values were dependent on pH within the range from 3.0 to 7.0. Competitive effect of other bivalent cations such as Ni2+ in Co2+ sorption equilibrium was confirmed; which is in agreement with the hypothesis of the decisive role of ion-exchange mechanism in metal sorption. The obtained data are discussed from the point of view of potential utilization of sludges as sorbents, i.e. in non-agricultural application.

The main aim of the present study was to find differences in the content of fatty acids and variations in elemental composition in beef samples of longissimus dorsi muscle related to cattle age and gender. A further goal was to describe interrelations among the selected variables (descriptors) characterising the samples. For this purpose, an extensive data table was compiled, which contains chemical descriptors specifying forty-six beef samples originating from four well-known Austrian grassland-based beef labels. The following descriptors were investigated: (a) concentrations of 33 fatty acids, (b) concentrations of 19 elements, (c) contents of dry-mass, protein, intramuscular fat, and ash, (d) total content of saturated fatty acids (SFA), mono-unsaturated fatty acids (MUFA), and poly-unsaturated fatty acids (PUFA), (e) total contents of omega-3 (n-3) and omega-6 (n-6) PUFA and their ratio. The correlation analysis provided a number of statistically significant correlations among the descriptors, which were concordant with the results of the principal component analysis and cluster analysis. Furthermore, the effect of age and gender of cattle (both acting as target factors) on the fatty acid content and elemental composition of beef was examined by analysis of variance (ANOVA) and appropriate non-parametric tests. Several important interrelations among the beef characteristics investigated were also discovered. Finally, the most relevant beef descriptors were utilised in linear discrimination analysis (LDA) for predicting the slaughter age of the cattle for beef authentication.

New wheat-rye bread fortified with cereal dietary fibre, β-glucan hydrogel, and sourdough starter culture was designed in this study. The impact of these additives on nutritional composition and antioxidant properties was investigated. Functional bread with extruded wheat bran (10.0 %), cereal β-glucan hydrogel (12.5 %), and lactobacilli starter culture was compared with traditional wheat-rye bread (control). The contents of basic nutrients (protein, fat, etc.), dietary fibre, biologically active compounds (polyphenols and flavonoids), qualitative and quantitative analysis of simple saccharides and phenolic acids (by HPLC) were analysed in both bread types. Antioxidant activity, measured by two spectrophotometric methods (2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid); ABTS and di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (2,2-diphenyl-1-picrylhydrasyl); DPPH, was also evaluated. The effect of the addition of the above ingredients, as compared with traditionally prepared bread, was examined in the postprandial study, in which glucose and insulin levels were determined. In comparison with the control bread, higher amounts of dietary fibre, flavonoid content, and antioxidant activity were attained in the designed bread. Consumption of the designed bread led to reduced glucose levels in healthy males (n = 10) 120 min after the ingestion of the functional bread compared with the control (p < 0.048). No statistically significant change in the insulin response in the volunteers was observed after consumption of the designed bread compared with the control.

This study compares two types of enzymes: maltogenic amylase (Novamyl 10000 BG) and lipase (Lipopan F BG, Lipopan Xtra BG), both separately and in combination, and seven hydrocolloids (guar gum, xanthan gum, carrageenan, β-glucan, carob gum, and carboxymethyl cellulose (CMC)) on the physical and sensory properties of a bakery product (white wheat bread). Their effect was observed on the baking characteristics of volume, specific volume, shape, mass, shelf-life (penetration and water activity test), and overall taste. The best results in shelf-life extension from the hydrocolloids were shown by β-glucan, a combination of xanthan gum + carrageenan and guar gum. From the enzymes, the best results were achieved with Lipopan Xtra BG and Novamyl 10000 BG + Lipopan F BG combination. The sensory properties (e.g. taste, colour, shape, aroma, elasticity, hardness) were evaluated by ten trained panellists, holding certification in sensory analysis. β-Glucan and Novamyl 10000 BG + Lipopan F BG combination increased the bread volume significantly and also were deemed to afford the most favourable taste.

Two tetra-coordinate Co(II) complexes, [CoCl2(bzfupy)2] and [CoCl2(p-tol)2] with N-donor ligands, are apparently mononuclear systems. The magnetic susceptibility at low temperature attains a maximum which is a fingerprint of the exchange interaction. The exchange coupling constant fitted to a model of 1D-magnetic chain yields J/hc = −0.50 cm−1 and −0.57 cm−1, respectively. The magnetic interaction is mediated by the π-π stacking in the first complex, and the short Cl…Cl contacts in the second.

Correlation analysis and, in particular, artificial neural networks (ANN) were used to predict the anti-mycobacterial activity of substituted 3-phenyl-2H-1,3-benzoxazine-2,4(3H)-diones (PBODs) by quantitative structure — activity relationship (QSAR) calculations. Initially, sixty-four derivatives were synthesised and biologically tested; ten further derivatives were proposed for future synthesis on the basis of the prediction results. The biological activity was originally expressed by minimum inhibitory concentration (MIC) against Mycobacterium tuberculosis; however, its transformed pMIC form was found to be more informative. Theoretical molecular descriptors of several types were selected to establish a primary drug model of the species which was expected to exhibit a substantial anti-mycobacterial effect. Lipophilicity and solubility indices, several basic molecular properties, quantum chemistry quantities as well as 1H and 13C NMR chemical shifts, were employed as the descriptors, enabling a very successful prediction of the pMIC values. The utilisation of in silico variables and simulated NMR data is highly advantageous in the first phase of the drug design, as they permit prediction of the compounds with a high expected activity, minimising the risk of synthesising less active species. The MIC values predicted at less than 4 μmol L−1 for six of the ten compounds suggested for further synthesis are better than the best value for the original set of compounds.

The aim of this study was to investigate bubble/drop formation at a single submerged orifice in stagnant Newtonian fluids and to gain qualitative understanding of the formation mechanism. The effects of various governing parameters were studied. Formation behavior of bubbles and drops in Newtonian aqueous solutions were investigated experimentally under different operating conditions with various orifices. The results show that the volume of the detached dispersed phase (bubble or drop) increases with the viscosity of the continuous phase (or dispersion medium), surface tension, orifice diameter, and dispersed phase flow rate. A PIV system was employed to measure the velocity flow field quantitatively during the bubble/drop formation, giving interesting information useful for the elucidation of the fundamental formation process at the orifice. It was revealed that the orifice shape strongly influences the size of the bubble formed. Furthermore, based on a simple mass balance, a general correlation successfully predicting both bubble and drop sizes has been proposed.

Cadmium concentration stabilization in a single input-single output continuous bioreactor via sulfide concentration, as the controlled and measured output state variable, was assumed. For the above process, a novel kinetic model of the sulfate-reducing process for cadmium removal was proposed and experimentally confirmed. This model has been extended to continuous operation, which is employed as a virtual plant to enable the implementation of the proposed controller. The considered nonlinear control law contains a sigmoid feedback of the given control error in order to regulate the sulfide concentration at the maximum value indirectly leading to cadmium concentrations meeting the environmental regulations. A theoretical frame of the closed-loop stability of the bioreactor is provided under the assumption that bounded trajectories occur in the bioreactor. Finally, numerical experiments proved satisfactory performance of the proposed methodology in comparison with the standard sliding-mode and linear PI controllers.

A novel cationic gemini surfactant has been readily synthesised in 70 % total yield. The functional gemini surfactant can act both as an emulsifier and an atom transfer radical polymerisation (ATRP) initiator in mini-emulsion polymerisation of methyl methacrylate (MMA), in which no other emulsifier was required. 1-(Dimethylamino)dodecane (N,N-dimethyldodecylamine, DMDA) was found to be a good ligand in the activator generated by electron transfer (AGET) ATRP reaction. Kinetic studies indicated that the polymerisation featured controlled/living radical polymerisation.

Natural Bulgarian diatomite modified by oxidation with sulfuric acid and H2O2 or by coating with manganese oxide was characterized considering its chemical composition, surface area, pore volume, and structure. Modified diatomites displayed larger surface area and pore volumes in comparison with untreated natural diatomite, which favored their sorption behavior. Sorption properties of diatomites towards Fe3+, Pb2+, Cu2+, Cd2+, Mn2+, Ni2+, Co2+, Cr3+, Pd2+, Ca2+, and Mg2+ were investigated and their sorption capacities were determined. Sorption properties of manganese oxide-modified diatomite were superior to those of diatomite modified by oxidation. Owing to its high sorption capacity towards Co2+, Ni2+, Pb2+, Cr3+, Fe2+, Cu2+, and Cd2+, the manganese oxide-modified diatomite is a promising low-cost sorbent for selective removal of milligram amounts of these toxic metal ions from contaminated water.

The polyaniline-PbO composites of various mass fractions were prepared by in situ polymerisation. The prepared samples were characterised by FTIR, and the dominant peaks confirmed the formation of polyaniline-PbO composites. The SEM study shows a granular agglomerated morphology, and increases with an increase in the lead oxide mass % in polyaniline. Direct current (DC) conductivity (σ DC) was studied as a function of temperature (T). From these studies, it was found that conductivity increased at higher temperatures due to the polarons hopping from one localised state to another. DSC studies reveal, the decrease in peak temperature from 273°C (pure PANI) to 169.2°C, 193.5°C, 218.4°C, 235.2°C, and 224.2°C, respectively for the various mass fractions (10 %, 30 %, 20 %, 40 %, and 50 %) of polyaniline-PbO composites.