Phenolic compounds from winemaking waste and its antioxidant activity towards oxidation of rapeseed oil

The effects of extraction parameters on bioactive compound contents of winemaking waste extracts (WWE) and its effect on rapeseed oil oxidative stability were evaluated. Research showed that the total phenols and anthocyanin contents and antioxidant activity (AA) of WWE significantly depended on the extraction parameters. Increasing the temperature (60 °C) and time (5 h) of extraction and an addition of water to ethanol statistically improved the rate of active component extraction. HPLC analysis showed that procyanidin B_2, catechin, gallic acid, γ‐resorcylic acid and p‐coumaric acid were the major phenolic compounds of WWE. Important correlations between total phenolic compounds quantified by HPLC and both DPPH and (ferric reducing antioxidant power) (FRAP) values were found. WWE added to the oil at three different levels clearly slowed down the process of fatty acid oxidation, inhibiting hydroperoxide formation by about 86%, comparable with BHT, while it was more effective than that of α‐tocopherol. When using volatile compound formation as a marker of lipid oxidation, WWE at the level of 2000 ppm were the most effective inhibitors of the decomposition of hydroperoxides. The research showed that the WWE are a rich source of phenolic compounds with powerful antioxidant activities and are suitable for preventing rapeseed oil oxidation.     

Analog filter pair design on the basis of a gyrator–capacitor prototype circuit

The paper presents an algorithmic approach to a low‐sensitivity design strategy for analog filter pairs based on a gyrator–capacitor prototype circuit. The general structure of the prototype circuit is proposed. It assumed that the generic structure of the prototype circuit can evolve, with the use of additional gyrators, into a circuit with increased redundancy. It is shown that symbolic analysis of the prototype circuit, used to formulate a set of nonlinear algebraic equations, is necessary to achieve a sufficiently high algorithm operation speed. To find a solution to this specific system of nonlinear algebraic equations, different numerical methods are compared. The modified Hooke and Jeeves algorithm is found to be the most effective. The elaborated algorithms and programs are illustrated with the seventh‐order filter pair example. The obtained filter is better than the filter obtained using LC ladder structures with respect to chip area and power consumption, and these improvements are obtained without loss of sensitivity properties. Copyright © 2010 John Wiley & Sons, Ltd.     

Computational Modelling of Retrofitting a Coal Fired Boiler Type OP-230 for Predicting NO<Subscript>X</Subscript> Reduction

This study focuses on a CFD modelling of biomass-derived syngas co-firing with coal in an older mid-sized PC-fired boiler of type OP-230 with low-emission burners on the front wall. The simulations were performed to determine whether the boiler can be retrofitted for the fulfilment of the prospective environmental protection regulations relating to levels of NO_X emissions. The improvement of the air staging via the dual-fuel technique was based on the indirect co-firing technology. The impact of two arrangements of dedicated syngas nozzles (below and above the existing coal burners), two syngas compositions and two heat replacements (5% and 15%) on the course of thermal processes in a furnace was tested. The reductions in NO_X emissions were predicted relative to the baseline when only coal is combusted. The highest reduction of about 38% was achieved with the syngas nozzles below the existing coal burners and 15% heat replacement. This arrangement of nozzles offers the residence time sufficient to co-fire coal with waste derived syngas. A lower reduction in NO_X emissions was obtained with the nozzles above the burners as the enlargement of local fuel rich zone near syngas injection becomes significant for 15% heat replacement. Results provide for the decreasing impact of methane content along with the increase of syngas heat input. The avoided CO₂ emissions through the syngas indirect co-firing with coal in the boiler are linear function of heat replacements.     

Effect of temperature and PH value on the stability of bioactive compounds and antioxidative activity of juice from colour-fleshed potatoes

The colour-fleshed potatoes represent a good raw material for the extraction of juices with a high content of biologically active compounds and a high antioxidant activity. The blue-fleshed potatoes turned out to be a rich source of total polyphenols, as they had approximately 3.5 times higher content of identified anthocyanidins. Regardless of anthocyanin composition, all juices made of colour-fleshed potatoes were highly stable. Both, high temperature, exposure time to these temperatures, and medium pH had no significant effect on changes in total polyphenols content of potato juices. The juices examined, especially these made of blue-fleshed potatoes, demonstrated a higher ABTS+ stability during their heating than during pH changes. In addition, a higher antioxidant activity of juices was determined at neutral and alkaline than at acidic pH value of the medium.     

Effect of Low-Friction Composite Polymer Coatings Fabricated by Electrophoretic Deposition and Heat Treatment on the Ti-6Al-4V Titanium Alloy’s Tribological Properties

Metallurgical and Materials Transactions A - In this work, polytetrafluoroethylene/polyetheretherketone (PTFE/PEEK 708) coatings were fabricated by electrophoretic deposition (EPD) and heat...     

Content of anthocyanins and glycoalkaloids in blue‐fleshed potatoes and changes in the content of α‐solanine and α‐chaconine during manufacture of fried and dried products

In the last ten or so years, potatoes with purple or blue‐flesh and derivative products, for example chips, have appeared on the European markets. The interest in this raw material and these products is increasing among both producers and consumers searching for novel and attractive choices. The anthocyanin content of the analysed potato varieties differed; a higher content of these pigments was determined in Blaue Elise var. potatoes. In blue‐flesh varieties, the prevailing anthocyanins were acylated glycosides: petunidin and malvidin. The production process of French fries, chips and puree caused a decrease in the content of glycoalkaloids in semi‐products and finished products, compared to the raw material. The greatest losses of α‐chaconine and α‐solanine were observed after tuber peeling (ca. 70%) and after frying (ca. 90%). French fries contained 3%, chips 16% and puree 17% of the initial amount of total glycoalkaloids. The losses of α‐chaconine and α‐solanine in the analysed semi‐products and finished products were at the same level, regardless of the processing technology applied.