Corrosion behaviour of thixoformed and heat-treated ZA27 alloys in NaCl solution

The influence of corrosion on the microstructure of thixoformed and heat-treated ZA27 alloys was investigated. The microstructure of ZA27 alloy was affected by heat treatment. The process of electrochemical corrosion occurs in both ZA27 alloys through the area of η phase. According to the results of immersion test and electrochemical measurements, the corrosion rate of the thixoformed ZA27 alloy is at least 50% lower than that of the thixoformed and thermally processed alloy. This indicates the unfavourable influence of applied heat treatment (T4 regime) on the corrosion resistance of the thixoformed ZA27 alloy.     

Synthesis and characterization of Fe doped titanium dioxide nanopowders

Titanium dioxide nanopowders, doped with different amounts of Fe³⁺ ions (0.3-5 mass%), were synthesized by acid-catalyzed sol-gel method in a non-aqueous medium. The obtained powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and determination of izoelectric points as well as particle diameters. Careful investigation of porous structure was provided by application of nitrogen adsorption-desorption method. Structure analysis showed that the obtained nanopowders exhibited the anatase crystal structure, independent of the amount of iron dopants. The presence of Fe³⁺ ions in anatase decreases the value of isoelectric point of undoped TiO₂. Unlike crystal structure, porosity parameters are strongly affected by the amount of iron ions incorporated in TiO₂ lattice. The mesoporosity of TiO₂ can be successfully controlled by changing the amount of iron dopants.     

Commercial TiO2 loaded with NiO for improving photocatalytic hydrоgen prоduction in the presence оf simulated solar radiation

Five NiO/TiO₂ materials with a different mass ratiо оf NiO tо TiO₂ (3.3, 6.7, 16.3, 23.7, and 36.8%) were synthesized by wet impregnation process and characterized by DR UV-vis, scanning electrоn micrоscоpe, transmissiоn electrоn micrоscоpy, X-ray diffractiоn methоd, N₂ physisorption, and temperature-programmed reduction. The characterizatiоn confirmed the existence of nano-sized cubic NiO on the commercial TiО₂. The оbserved interactiоn between TiO₂ and NiО phases confirmed that the оbtained material dоes nоt constitute a physical mixture оf twо species. The photocatalytic hydrоgen generatiоn efficiency [mоnitored by gas chromatography–thermal conductivity detector (GC-TCD)] of these materials from methanol-water mixtures under simulated solar radiation and artificial UV radiation was investigated. For some synthesized NiO/TiO₂ materials, higher photocatalytic efficiency was found compared with the commercial TiO₂ Degussa P25 catalyst. Also, the obtained results showed that 0.125 g L⁻¹ of 6.7%NiO/TiO₂ and 5% (v/v) of methanol were the optimal operating parameters. Furthermоre, fоr the mоst efficient phоtоcatalytic system under the influence оf simulated solar radiation, a 1.8 times higher hydrоgen prоduction rate was achieved cоmpared tо that under the influence оf artificial UV radiatiоn.     

Effect of low‐trans margarine on physicochemical and sensory properties of puff pastry1

The influence of the low‐trans (<1% of total fatty acids) puff pastry margarine and the rest period between laminating on dough physical characteristics and puff pastry quality was investigated. Experiment was planed according to factorial plan 3² with independent variables: quantity of puff pastry margarine (35–55% based on flour, variation interval 10) and rest period (15–45 min, variation interval 15). The experiment involved two margarine samples (MLT1 and MLT2) of similar fat phase composition, but whose physical properties were, statistically speaking, significantly different. The results show that the pastry containing 35% of margarine MLT1 and allowing the rest period of 30 and 45 min has a lift of above 4.0, it is of minimal firmness and has a high specific volume (3.5 cm³ g^?1). Having used puff pastry margarine MLT2, the highest quality of dough and pastry was achieved in the sample containing 55% of margarine and with the maximum rest period of 45 min. The sample mentioned showed an excellent lift of 5.3 and had a specific volume of 4.0 cm³ g^?1, but it as well exhibited the maximal firmness of pastry. The application of puff pastry margarine MLT1 can result in a satisfactory quality of pastry, but it can also cause a reduction in the fat content by 7.5% and in the content of trans fatty acids by two times, while the energy value is reduced by 12% when compared with the pastry containing puff pastry margarine MLT2.     

Plasma assisted degradation of phenol solutions

Solutions of 2-chlorophenol, 4-chlorophenol and 2,6-dichlorophenol in bidistilled and water from the river Danube were treated in plasma reactor. In this reactor, based on coaxial dielectric barrier discharge at atmospheric pressure, plasma is formed over a thin layer of treated water. After one pass through the reactor, starting chlorophenols concentration of 20 mg/l was diminished up to 95%. Kinetics of the chlorophenols degradation was monitored by High Pressure Liquid Chromatography method (HPLC).     

Intergranular Nanostructure Effects on Strength and Toughness of Si3N4

Strength, toughness, microstructure, and atomic adsorption arrangement in silicon nitrides with MgO and RE₂O₃ additions (RE = La, Gd, Y, Lu) were examined. Mechanical properties were high for La, Gd, and equal La–Lu additions, but surprisingly were progressively lower for Y‐ and Lu‐doped samples. The lower strength and toughness were associated with fewer visible crack deflections and grain bridges. Detailed microstructural analysis of the Lu‐doped material revealed a complex intergranular nanostructure with variable Lu content and Si₃N₄ nanocrystals. Furthermore, the Lu‐rich areas showed an extra Lu‐adsorption site on the Si₃N₄ prismatic planes not previously observed in other studies. This inhomogeneous structure was attributed to grain growth impingement and higher viscosity of the Lu‐doped oxynitride glass that slows homogenization. The Y‐doped material with nearly identical glass viscosity demonstrates intermediate behavior. Finally, substituting half of the Lu₂O₃ with La₂O₃ resulted in a homogenous intergranular structure, attributed to a lower viscosity of the oxynitride glass phase, and high mechanical properties. Overall, care must be taken when adapting Si₃N₄ processing parameters for the smaller ionic radius rare earth dopants such as Lu and Y.     

Shelf-life of a dragee product based on sunflower kernel depending on packaging materials used

In this study, we investigated the quality and shelf‐life of a dragee product obtained by coating a confectionery sunflower kernel with sugar syrup. The product was packed in oriented polypropylene/oriented polypropylene, oriented polypropylene/metallised oriented polypropylene, polyester/polyethylene and kept at room temperature in daylight for 5 months. At the beginning of the experiment, the dragee product was in the category of excellent sensory quality (total score of sensory evaluation is between 18.0 and 20.0) in terms of its colour, smell, taste, mastication and structure. During the storage, these properties changed and the product lost its stability. Peroxide value in the dragee product increased from 0.5 to 9.0 mmol O/kg during the 5 months of storage. The free fatty acid content also increased from 1.3% in fresh dragee product to 2.5% after 5 months of storage. The packaging material metallised polyester/polyethylene, labelled metPET/PE, has the lowest oxygen permeability (8.0 mL m^?2/dan Δp 1 bar) and because of this it had the strongest influence in the prevention of hydrolytic and oxidative changes in the final product.