Volume 70, Issue 11

An organic–inorganic hybrid optical sensor (PQ-SBA-15) was designed and prepared through functionalisation of the SBA-15 surface with 3-piperazinepropyltriethoxysilane followed by covalently attaching 8-hydroxyquinoline. Characterisation techniques, including FT-IR, thermal gravimetric, N 2 adsorption-desorption and X-ray powder diffraction analyses, showed that the organic moieties were successfully grafted onto the surface of SBA-15 without the SBA-15 structure collapsing. The evaluation of the sensing ability of PQ-SBA-15 using fluorescence spectroscopy revealed that the PQ-SBA-15 was a selective fluorescence enhancement-based optical sensor for Al 3+ in water in the presence of a wide range of metal cations including Na + , Mg 2+ , K + , Ca 2+ , Cr 3+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ and Pb 2+ with a limit of detection of 8.8 × 10 −7 M. In addition, good linearity was observed between the fluorescence intensity and the concentration of Al 3+ .

The novel derivative of quercetin 3′- O -(3-chloropivaloyl)quercetin (CPQ) inhibited α -glucosidase in a non-competitive manner with an efficacy exceeding that of the parent quercetin. In addition, it inhibited aldose reductase isolated from rat lenses with an IC 50 in the low micromolar range and attenuated sorbitol accumulation in isolated rat eye lenses with an activity comparable with that of quercetin. Moreover, it scavenged stable free-radicals of DPPH more efficiently than did quercetin. By inhibiting α -glucosidase and affecting both the polyol pathway and oxidative stress, CPQ represents a promising agent for the multi-targeted pharmacology of diabetic complications.

The production of a high-content galacto-oligosaccharides mixture (GOS) by immobilised β -galactosidase and yeasts in LentiKats® lens-shaped polyvinylalcohol (PVA) capsules was evaluated. Galacto-oligosaccharides were produced from lactose (300 g L -1 ) by immobilised fungal β -galactosidase and the yeast Kluyveromyces marxianus in polyvinylalcohol hydrogel in batch mode. The low-content GOS mixture produced by the immobilised enzyme consisted of 71.7 g L -1 with a final purity of 22.7 % after 30 h of transgalactosylation reaction at 30°C and pH 4.5. The low-content GOS mixtures were subsequently used in 20 repeated batch runs with immobilised yeasts for increasing the GOS content. Digestible sugars were fermented to ethanol and the resulting mixture consisted of 88 mass % of GOS after 26 h of fermentation. The PVA lenses exhibited high fermentative stability without any mechanical deformations.

Inulin and glycerol were used as substrates for efficient erythritol and citric acid production by newly engineered Yarrowia lipolytica strains. Hydrolysis of inulin by the Y. lipolytica Wratislavia K1 strain was established by expressing the Kluyveromyces marxianus INU1 gene. Erythritol was produced in two stages: inulin was used for biomass formation, followed by erythritol biosynthesis initiated by glycerol addition. The highest titer of erythritol obtained, 120.9 g L −1 with the yield of 0.6 g g −1 , was produced by the K1 INU 6 strain. Moreover, the K1 INU 6 strain in fed-batch culture produced a high amount of citric acid: 105.2 g L −1 after 235 h from 200 g L −1 of inulin. Maximum activity of inulinase during this culture was 14000 U g −1 of cell dry mass. The presented study proves the potential of new Y. lipolytica transformants for efficient erythritol and citric acid production from inexpensive raw materials such as inulin and glycerol.

Surfactant-stable keratinases with good properties are promising candidates for extensive applications in detergent industries. A novel fungal keratinase-producing strain, Gibberella intermedia CA3-1, is described in this study. The keratinase production medium was optimized and composed of 10 g L −1 of wool powder, 5 g L −1 of tryptone, 10 g L −1 of maltodextrin and 0.5 g L −1 of NaCl. Keratinase activity was increased up to 109 U mL −1 from 15 U mL −1 by culture optimization. The optimal reaction pH and temperature of the enzyme were 9.0 and 60°C, respectively. The keratinase activity could be improved by sodium dodecyl sulphate (SDS), and it remained stable in the presence of several surfactants and commercial detergents. G. intermedia keratinase was proved to completely remove blood stains from cotton cloth when combined with detergents. These findings indicate that this fungal keratinase is a promising catalyst for the application in detergent industry. To our knowledge, this is the first report on keratinase production by Gibberella genus.

Alumina-supported potassium (K/Al 2 O 3 ) catalysts using pseudo-boehmite as the precursor were prepared by the impregnation/calcination method, characterised by XRD, SEM, ICP, N 2 adsorption/desorption, CO 2 -TPD methods and TG analysis, and applied to the vapour-phase condensation of methyl propionate with trioxane to produce methyl methacrylate. The results showed the catalysts’ properties to be mainly affected by the calcined temperature ( T C ) and the crystal structure. The sample calcined at 1100°C exhibited the highest catalytic activity when mixed phases were formed and provided the appropriate specific surface area ( S BET ) and surface basic properties. The effects of T C , K-loading and reaction conditions on the catalytic performance were also investigated in a fixed-bed reactor. The yield of methyl methacrylate attained 29.2 % under the optimised conditions, and the deactivated catalyst could be completely regenerated by calcination.

This study focuses on the use of slow pyrolysis with controlled temperature increase for the thermal decomposition of pre-dried wastewater sludge. A combination of two significantly different methods was applied to investigate the pyrolysis process. The first of the experimental approaches was based on laboratory apparatus with a vertical batch retort equipped with external electrical heating. Samples of the liquid and gaseous products of the pyrolysis were taken at defined intervals throughout the pyrolysis process and were subsequently analysed. The second method involved the application of thermal analysis to the identical sludge, completed by online analysis of the pyrolysis products generated. This second method included thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). The results obtained by both methods demonstrate that waste water sludge can be effectively converted into pyrolysis gas and oil with good combustion properties.

Synthesis of new efficient compounds is becoming urgent due to the resistance of organisms to drugs. Salen derivatives have interesting therapeutic and industrial applications. A coumarin based derivative of salen, 7-hydroxy-8-((E)-((2-((E)-((7-hydroxy-5-methyl-2-oxo-3,8a-dihydro-2 H -chromen-8-yl)methylene)amino)-4-methylphenyl)imino)methyl)-5-methyl-2 H -chromen-2-one (L), and its copper complex, CuL, have been synthesized and characterized. Antibacterial and antioxidant activity of these compounds have been evaluated and electronic, optical and molecular properties have been calculated using density functional theory (DFT) with B3LYP. The results were correlated with the biological activity and reactivity of the compounds. Experimental and theoretical calculations indicate that the studied copper complex has the potential to function as a drug. © 2016 Institute of Chemistry, Slovak Academy of Sciences

Open cell 3D titanium carbide/silicon carbide (TiC/SiC) composite was oxidised to titanium oxide/silicon carbide (TiO 2 /SiC) following different temperature profiles in a thermal gravimetric analysis (TGA) instrument in continuous air-flow and static air (oven) environments. The TiC oxidation to anatase, starting at temperatures over 450°C, was confirmed by Raman spectroscopy and X-Ray diffraction (XRD). By increasing the temperature, the mass fraction of anatase diminished, while the mass fraction of rutile increased. SiC oxidation started at 650°C when a mixture of TiO 2 /SiO 2 /SiC could be observed by Raman, XRD and HRTEM.

Toxicity of zinc oxide nanoparticle (ZnO-NPs) powder and water soluble salt of Zn (ZnCl 2 ) to the annelid Enchytraeus crypticus was tested in agarose gel. Influence of the spiking method on the resulting size of nanoparticles and on E. crypticus mortality was studied. Two methods of ZnO-NPs powder (mean particle size diameter of 10 nm) introduction into the exposure media were used. In the first method, the nano-powder was initially cryogenically ground with dry agar followed by an addition of water. The second procedure began with re-suspension of nanoparticles in demineralized water containing a dispersant (sodium pyrophosphate decahydrate). The obtained colloid was subsequently mixed with hot agar gel. Relative mortality in worms observed after 96 h of their exposure to the ZnO-NPs concentrations (all in mg of ZnO-NPs per kg of agar) of 50, 100, 200, 500 and 1000 in the cryogenically ground medium ranged between 28.9 % and 34.4 % and it did not exhibit any concentration dependence. When the second method of exposure media preparation was applied, the relative mortality ranged from 0 % to 66.6 % in the same concentration region depending on the concentration. Scanning electron microscopy (SEM) revealed the presence of large agglomerates (1–10 µm in diameter) in the media prepared by cryogenic grinding with the highest concentration of ZnO-NPs. Neither the cryogenically ground media with lower ZnO-NPs concentrations nor any media prepared from colloidal solutions contained agglomerates exceeding 100 nm, detectable by SEM. Hydrodynamic diameters of particles in the colloids used in the second method of agar preparation were measured using dynamic light scattering (DLS) and ranged between 164 nm and 240 nm. The observed toxicity was thus clearly dependent on the size of ZnO-NPs agglomerates and the technique of exposure media preparation. Experimentally detected LC 50 value for dissolved Zn 2+ was 37.2 mg kg −1 in agar. The same concentration of Zn induced an approximately 30 % mortality of E. crypticus when administered in form of cryogenically ground ZnO-NPs with agar. No observable effects were found at this ZnO-NPs concentration when the exposure medium was prepared from the colloid solution.

A series of novel Schiff base derivatives containing 4(3 H )-quinazolinone moiety were synthesised and their antibacterial activities against tobacco and tomato bacterial wilts evaluated in vitro. Out of the synthesised compounds, 5g , 5j , 5n , 5m and 5p exhibited excellent antibacterial activities against tobacco bacterial wilt, with half maximal effective concentrations (EC 50 ): 160.34, 158.03, 125.94, 148.09 and 133.67 (all in μg mL −1 ), respectively, which were better than the EC 50 of thiodiazole–copper (216.70 μg mL −1 ). Compounds 5j , 5n and 5o also showed good antibacterial activities against tomato bacterial wilt, with EC 50 of 95.20, 90.03 and 83.21 (all in μg mL −1 ) respectively, which were better than the EC 50 of thiodiazole–copper (99.80 μg mL −1 ). These compounds may prove to be useful as potential antibacterial agents.

The aza-Pudovik reaction of N -benzyl aromatic and aliphatic aldimines with dimethyl H -phosphonate was found to be accelerated significantly when carried out in an external magnetic field. Its conversion rates were analyzed and compared with those obtained during the aza-Pudovik reaction carried out under standard conditions. Magnetic acceleration was found to have a similar degree as in that observed in the Kabachnik–Fields reaction. However, the formation of the starting imines was found not to be susceptible to constant magnetic field – no acceleration was observed.