Volume 66, Issue 2

G-quadruplexes are a family of DNA secondary structures resulting from the folding of a guanine-rich sequence. Targeting quadruplexes by small molecules is an approach that is currently being studied with the aim of exploring their biological roles and developing new anti-cancer agents. There is evidence that the formation of G4 structures by telomeric DNA can be used to inhibit the enzyme activity of telomerase, and thereby to activate the pathway to senescence in tumour cells. It was previously shown that the papaverine oxidation products 6a,12a-diazadibenzo-[a,g]fluorenylium derivative (ligand I) and 2,3,9,10-tetramethoxy-12-oxo-12H-indolo[2,1-a]isoquinolinium chloride (ligand II) bind to G-quadruplex representing the human telomeric sequence. These ligands possess the ability to inhibit telomerase and polymerase action at the micromolar level. Here we report a DNA binding study on these two ligands and a new derivative 2-(2-carboxy-4,5-dimethoxyphenyl0-6,7-dimethoxyisoquiloliniuminner salt (ligand III) in order to evaluate their binding selectivity to samples of nucleic acids (ssDNA, dsDNA, triplexes, and quadruplexes). Simultaneous investigations on several DNA-ligand complexes carried out using an equilibrium dialysis approach revealed pronounced binding selectivity of ligand I and ligand II to tetraplex DNA structures over the doublestranded DNA forms.

Ethanol production in a bioreactor with integrated membrane distillation (MD) module has been investigated. A hydrophobic capillary polypropylene membrane (Accurel PP V8/2 HF), with an external/internal diameter ratio, d out/d in = 8.6 mm/5.5 mm and pore size 0.2 μm, was used in these studies. The products (mainly ethanol and acetic acid) formed during the fermentation of sugar with Saccharomyces cerevisiae inhibited the process. These products were selectively removed from the fermentation broth by the MD process, which increased the efficiency of the conversion of sugar to alcohol from 0.45 g to 0.5 g EtOH per g of fermented sucrose. The bioreactor efficiency also increased by almost 30 %. Separation of alcohol by the MD generates a higher yield of ethanol in the permeate than in the broth. The enrichment coefficient amounted to 4-8, and depended on the ethanol concentration in the broth. The separated solutions did not wet the membrane in use for 2500 h of the MD experiments and the retention of inorganic solutes was close to 100 %.

Studies of membrane wettability in the membrane distillation process were performed with the application of hydrophobic capillary membranes made of polypropylene. Three kinds of Accurel PP membranes (Membrana GmbH, Germany) differing in the diameter of capillaries and pores as well as in the wall thickness were used. It was confirmed that membranes with lower wall thickness and larger pore size provide higher yields of the process. The studies demonstrated that the pores of used membranes located close to the external surface of capillaries are several times larger than those located inside the membrane wall. Based on air permeability measurements it was found that external surface of the membranes with such large pores was completely wetted by water after 50–80 h of membrane distillation. However, the pores located inside the wall with the diameter below 1 μm were not wetted and electrical conductivity of the obtained distillate was maintained at the level of 3–6 μS cm−1.

The motivation for this work was to define the reburning potential of sewage sludge (SS) gasification gas (syngas). A numerical simulation of the co-combustion process of syngas in a hard coal-fired boiler was made. All calculations were performed using the Chemkin program and a plug-flow reactor model was used. The calculations were modelled using the GRI-Mech 3.0 mechanism. The highest conversions for nitric oxide (NO) were obtained at temperatures of approximately 1000 K to 1200 K. The highest reduction efficiency was achieved when the molar flow-ratio of the syngas was 15 %. The combustion of hard coal with sewage sludge-derived syngas reduces NO emissions and the amount of coal needed to produce electricity and heat. Furthermore, advanced reburning, a more complex process, achieved an efficiency of up to 80 %. Calculations show that the syngas thus analysed can provide better results.

The intrinsically multi-factorial pathological trend of spinal cord injury is probably the most important reason behind the absence of efficient therapeutic strategies. Therefore, recent studies suggest the use of new tools combining the delivery of both cells and drugs. Systems which are able to perform multiple controlled delivery of different therapeutic agents have gained particularly strong interest. Hence, in order to avoid trial and error approaches, several studies were performed following the classic chemical engineering multiscale approach: tuning microchemistry to manipulate macro properties in order to satisfy specific medical needs as injectability, low stress on target tissues, ability to retain liquids, capability of carrying living cells, and possibility to control the delivery of drugs. In this framework we focused on injectable agarose-carbomer based hydrogels applying he results of our studies performed in the past two years: in vitro biocompatibility, physical chemical studies, drug delivery transport phenomena investigation, and in vivo biocompatibility in uninjured Brainbow mice.

Photodegradation of endocrine disrupting butylparaben (BP) in aerated aqueous solutions was studied using 4,4′,4″,4‴-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulphonic acid) (TPPS4), as a sensitiser. Influence of various parameters, such as initial sensitiser and BP concentration, pH of the reaction solution and oxygen content in the reaction solution, on the photosensitised oxidation was examined. It was found that the dominant pathway of BP degradation occurred in the reaction with molecular singlet oxygen 1O2, i.e. via photosensitised oxidation mechanism of type II. Kinetic parameters of the BP reaction with 1O2 were estimated.

The topic of this study is the pre-treatment of substrates for anaerobic digestion. Two different substrates of algae Scenedesmus subspicatus (SAG 86.81), Chlorella kessleri (LARG/1) and foliage of Prunus serrulata were subjected to anaerobic digestion. A mixture of commercially available cellulolytic enzymes (Analytical science s.r.o., Modra, Slovakia) was used for anaerobic treatment of algae while the foliage of Prunus serrulata was pre-treated by lignolytic fungi. The highest production of methane per mass of volatile solids was reached with untreated Chlorella kessleri at (0.59 ± 0.04) L g−1. The addition of cellulolytic enzymes did not increase the production of methane from the algal substrate; however, a faster substrate degradation and thus also higher speed of methane production at the beginning of cultivation was achieved. After foliage pre-treatment by fungal isolate Pleurotus pulmonarius, isolated from natural habitats, the methane production increased five times. In this way we were able to speed up the processes of biological degradation of ligno-cellulose materials and thereby to increase the production of methane. Our results show the possibility of using algae as a suitable substrate for biogas production. On the other hand, also aerobic pre-treatment of foliage (Pleurotus pulmonarius) presents a successful way for speeding up the degradation of ligno-cellulose waste leading to increased methane yields.

Active packaging materials are the subject of research because their performance exceeds that of traditional packaging. From this class, antimicrobial materials extend the shelf-life of products and reduce the risk of contamination by pathogens. In this paper, new composite materials with antimicrobial properties are obtained by using polyvinyl alcohol and bacterial cellulose powder. Potassium (2E,4E)-hexa-2,4-dienoate was used as the antimicrobial agent. The films thus obtained were characterised using Fourier-transform infrared spectroscopy and scanning electron microscopy. Mass transfer phenomena concerning the release of potassium (2E,4E)-hexa-2,4-dienoate were investigated. The results indicated that the new biocomposite films could be used as antimicrobial packaging materials.

Antimicrobial packaging protects the product from the external environment and microbial contamination, conferring numerous advantages on human health. Interest in biopolymers as packaging materials has considerably increased recently. Bacterial cellulose is an interesting biomaterial produced as nanofibrils by Acetobacter xylinium and is a promising candidate due to its remarkable properties. New composite materials with antimicrobial properties were developed in this work, containing poly(vinyl alcohol) (PVA) as polymer matrix and ground bacterial cellulose (BC) as reinforcing fibres. Sorbic acid was used as an antimicrobial agent because it is a preservative recognised in the food industry. The materials obtained were studied using Fourier-transformed infrared spectroscopy (FTIR). The swelling rate of the composites was also measured. Release experiments of sorbic acid from the composite films into water were performed and the mass transfer phenomena were investigated using Fick’s law of diffusion. The antimicrobial effect was tested against Escherichia coli K12-MG1655. The results obtained indicated that the new biocomposite films could be promising antimicrobial food packaging materials.

The determination of the content of stable isotopes, 18O and 2H, respectively, in juice water facilitates the distinction between authentic juices and juices made from concentrates by redilution with tap water. At the same time, the detection of C4 cane or corn-derived sugar syrups in fruit juices which are produced from C3 fruit types is thus facilitated by the characteristic differences in 13C/12C, expressed as δ 13C (‰) values due to photosynthetic CO2 assimilation via the C3−, C4−, and crassulacean acid metabolism pathways. In this study, the quantitative determination of water added to an authentic juice, on the basis of δ 18O, and δ 2H values, respectively, was successfully performed. Also, the δ 18O, and δ 2H of juice water and δ 13C of the whole juice in 18 samples were also determined. The results obtained provided us with the possibility of distinguishing between authentic fruit juices and those obtained by redilution of concentrated fruit juices and the detection of C4 type added sugar.

The aim of this work was to evaluate the influence of ostazine dyes on the microbial population in environment. These dyes act as photosensitizers after irradiation by visible light. The photodynamic effect was induced in this way. The effect of irradiated water solutions of ostazine green, ostazine yellow, and ostazine blue on the Escherichia coli growth was tested. Furthermore, the effect of these dyes (at c = 3.5 μg mL−1) on bacterial growth was evaluated after their pretreatment by the Fenton reaction. Dramatic changes in dyes’ toxicity were observed after coloured solutions were pretreated by the Fenton reaction.