Mass Exchange at the Metal‐Mould Flux Interface

Mass exchange between liquid steel and the mould flux leads to the oxidation of some elements in the steel and the reduction of slag components. In the continuous casting process, where metal initially solidifies at the metal‐slag interface, reaction products generated there can be cached by the growing solidification front. The disruptions of the interface promote the entrapment of flux particles additionally. They can cause surface defects with quality damages of the cast products as a consequence. These investigations are focused on the contact area between liquid mould flux and metal. The samples were taken from the mould during the continuous casting process. The results show that layers up to approximately 300 nm from the slag/metal interface represent a specific reaction space. The transport of oxygen near the interface and the charge transfer is explained on the basis of the ionic character of the slag. Sodium in this layer on the slag side plays a special role in the oxygen transport besides of the iron ions. The mass transfer rate of oxygen crossing the interface is calculated from measured data and conclusions concerning the stability of the interfacial tension are made.     

STT and DTT Diagrams of Austenitic Cr–Mn–Ni As‐Cast Steels and Crucial Thermodynamic Aspects of γ → α′ Transformation

The mechanical behavior and microstructure evolution during deformation of novel austenitic Cr–Mn–Ni as‐cast steels with varied Ni content were investigated at various temperatures using static tensile tests, optical microscopy, and the magnetic scale for the detection of ferromagnetic phase fraction. To summarize all knowledge about the deformation‐induced processes, the STT and DTT diagrams were developed for Cr–Mn–Ni steels. The diagrams illustrate the different deformation mechanisms depending on temperature and tension load, and quantify the elongation of the deformation mechanisms. The deformation‐induced ε‐ and α' martensite formation and twinning – the TRIP and TWIP effects – occur in the Cr–Mn–Ni steels depending on the chemical composition and temperature. The differences of deformation‐induced processes depend on thermodynamics and are confirmed by thermodynamic calculations. The nucleation threshold of γ → α′ transformation was determined for the investigated Cr–Mn–Ni steels.     

Dietary vitamin E effect on color stability and sensory assessment of spoilage in three beef muscles

Effects of dietary vitamin E supplementation (1204 IU/head/day) for 122 days on color stability and microbial load on beef m. longissimus lumborum (LL), m. gluteus medius (GM) and m. psoas major (PM) were studied by subjective and objective evaluation. Color stability of these muscles followed the order LL > GM > PM (p < 0.05). Vitamin E-treated LL, GM and PM showed less metmyoglobin formation, higher a^* values and lower hue angle values than controls during storage at 4 °C (p < 0.05). Sensory evaluation demonstrated that panelists preferred the appearance of vitamin E-treated LL, GM and PM beef steaks. Vitamin E supplementation did not affect total microbial load on LL, PM and GM and did not influence panelists' olfactory assessment of microbial spoilage of beef. Endogenous -tocopherol concentration and lipid stability of microsomal fractions of LL, GM and PM were greater (p < 0.05) in vitamin E-treated muscles relative to controls. There was no muscle effect on the pro-oxidant activity of microsomes towards oxymyoglobin oxidation (p > 0.05). Oxymyoglobin stability was greater in the presence of microsomal fractions obtained from vitamin E-treated muscle than in those from controls. Dietary vitamin E supplementation delayed oxymyoglobin oxidation in LL, PM and GM muscle and increased the color shelf-life of these muscles without affecting total microbial load.     

Alizarin Red S as an electrochemical indicator for saccharide recognition

In addition to the well-established spectroscopic Alizarin Red S (ARS) assay for the determination of binding constants between arylboronic acids and different saccharides, we report the use of ARS as a reporter in an electrochemical set-up. The electrochemical properties of ARS, the binding to phenyl boronic acid (PBA) and the competition with fructose in phosphate buffer at pH 7.4 were investigated by cyclic voltammetry (CV). By choosing a negative scan direction (starting at +0.2 V), a quasi-reversible process was detected at E⁰′ = −0.59V with ΔE_p = 0.1V. An irreversible oxidation peak at +0.42 V could also be detected. These peaks are characterised both as a 2-proton-2-electron transfer and corresponds to the oxidation and reduction of the anthraquinone or the ortho-quinone moiety. After addition of phenylboronic acid a new oxidation peaks occurred at −0.42 V which correlates with the ARS–PBA interaction. The peak current increased with increasing phenylboronic acid concentration according to the release of BA and formation of the ARS–PBA ester. After addition of fructose the peak current decreases again, in proportion to the fructose concentration, enabling the use of ARS as an electrochemical reporter for fructose detection up to 50 mM. Also the interaction with other cis-diol containing compounds such as sorbitol, mannitol, glucose and mannose was investigated and a dependence based on already published binding constants to phenylboronic acid could be shown.     

Comparative Study on Selected Properties of Modified Polyurethane Foam with Fly Ash

The aim of the article is to compare two types of fly ash (from the fluidized and pulverized coal combustion process) as a filler for rigid polyurethane foam. Pulverized fly ash (PFA) is widely used in building materials, while fluidized fly ash (FFA) is not currently recycled, but landfilled. The produced rigid polyurethane foams were reinforced with 5 and 10% by weight addition of fly ash from two different types of boilers. The foaming process, physical properties, morphologies and thermal degradation were subject to comparative analysis. The research indicated that fly ash intensifies the reactions of foam synthesis, most commonly, polyurethane (PU) foam with an addition of 10% PFA. What is interesting is that both ashes can be used in PU foam technology as they do not cause deterioration of the physical parameters. As shown, the addition of filler affects the morphology and impairs the brittleness. Additionally, the use of fly ash from coal combustion in the technology of polyurethane materials complies with the guidelines of the circular economy stated in the European Union legislation. Partial replacement of petrochemical components with waste filler also reduces the total energy consumption in the production of PU composites.