Kinetics and mechanism of reactions between iron oxides and iron‐carbon melts

The reaction between iron oxides and iron‐carbon melts was studied in the temperature range 1523–1973 K. Pellets made from three different sources of iron oxides were added onto the melt surface, and the reaction time was measured through the constant volume pressure increase (CVPI) method. The effects of reaction temperature, oxide and melt surface areas, oxide type and weight on reaction time were evaluated. Analysis of partially reduced pellets through SEM was also performed. It has been determined that the reaction time increases as the pellet weight increases, and decreases as the temperature, the contact area between the oxide and the melt and the surface area of the melt increase. Examination of partially reduced pellets had shown that the reduction occurs topochemically. Based on the results, it is proposed that the overall reaction rate is determined by the consecutive reactions of dissociation of FeO and formation of CO.     

High-resolution ultrasonic spectroscopy for analysis of industrial emulsions and suspensions

This article describes the application of high-resolution ultrasonic spectroscopy (HR-US) for the analysis of industrial emulsions and suspensions. The benefits of HR-US are discussed, including the ability to perform a direct analysis of emulsions and suspensions, which would otherwise be impossible, require significantly more effort in the laboratory, or produce erroneous results. The HR-US 102 spectrometer is also introduced. Manufacture of this laboratory-scale instrument is now possible due to recent technological advances in HR-US. The article outlines the principles of the HR-US technique and illustrates the application of the HR-US 102 spectrometer for analysis of absorption of ligands on the surface of particles, thermal stability, and effects of thermal history on microstructure of emulsions, crystallization, and particle sizing in diluted and concentrated emulsions.     

Lost work and its reduction in refrigeration processes

The theory of lost work as applicable to compression refrigeration processes is outlined. Practical cases approximating mine refrigeration conditions are analysed. Possible methods of lost work reduction are examined and suggestions are made regarding improvement.     

Determination of Chromium Oxidation States in Part of the System CaO─3CaO · Cr2O3 in Air

The aim of the present work was to identify the structural characteristics of calcium chromium oxide formed at molar ratios CaO/Cr₂O₃≥ 3/1 and at elevated temperatures by the use of nondestructive techniques: instrumental neutron activation analysis (for determination of the total chromium content), electron paramagnetic resonance, magnetic susceptibility (for determination of chromium oxidation states), X-ray diffraction, and scanning electron microscopy. Our results suggest formation of the 3CaO · Cr₂O₅ compound, while at larger molar ratios only a small portion of Cr is incorporated into the crystalline CaO lattice as paramagnetic Cr³⁺.     

Analyzing the Semantics of Point Spaces through the Topological Weighted Centroid and Other Mathematical Quantities: The Hidden Geometry of the Global Economic Order

For many spatial processes, there is a natural need to find out the point of origin on the basis of the available scatter of observations; think, for instance, of finding out the home base of a criminal given the actual distribution of crime scenes, or the outbreak source of an epidemics. In this article, we build on the topological weighted centroid (TWC) methodology that has been applied in previous research to the reconstruction of space syntax problems, for example, of problems where all relevant entities are of spatial nature so that the relationships between them are inherently spatial and need to be properly reconstructed. In this article, we take this methodology to a new standard by tackling the new and challenging task of analyzing space semantics problems, where entities are characterized by properties of a nonspatial nature and must therefore be properly spatialized. We apply the space semantics version of the TWC methodology to a particularly hard problem: the reconstruction of global political and economic relationships on the basis of a small‐dimensional qualitative dataset. The combination of a small set of spatial and nonspatial sources of information allows us to elucidate some intriguing and counterintuitive properties of the inherent global economic order and, in particular, to highlight its long‐term structural features, which interestingly point toward the idea of longue durée developed by the distinguished French historian Fernand Braudel.     

Influence of biodiesel on engine combustion and emission characteristics

This paper discusses the influence of biodiesel on the engine combustion characteristics. The considered fuel is neat biodiesel from rapeseed oil. The considered engine is a bus diesel engine with injection M system. The engine characteristics are obtained by experiments and numerical simulation. The results obtained with biodiesel are compared to those obtained with mineral diesel under various operating regimes. In this way, the influences of biodiesel usage on the injection pressure, injection timing, ignition delay, in-cylinder gas pressure and temperature, heat release rate, exhaust gas temperatures, harmful emissions, specific fuel consumption, and on engine power are analyzed. Furthermore, the relationships among fuel properties, injection and combustion characteristics, harmful emissions, and other engine performance are determined. Special attention is given to possible explanations of higher NO_x emission in spite of lower in-cylinder gas temperature.     

Mineralogical and microstructural studies of mortars from the bath complex of the Roman villa rustica near Mošnje (Slovenia)

This study deals with the characterization of mortars collected from bath complex of the Roman villa rustica from an archeological site near Mošnje (Slovenia). The mortar layers of the mosaics, wall paintings and mortar floors were investigated. A special aggregate consisting of brick fragments was present in the mortars studied. The mineralogical and petrographic compositions of the mortars were determined by means of optical microscopy, X-ray powder diffraction and FTIR spectroscopy. Analysis of aggregate–binder interfaces using SEM-EDS revealed various types of reactivity rims. In order to assess the hydraulic characteristics of the mortars, the acid-soluble fractions were determined by ICP-OES. Furthermore, the results of Hg-porosimetry and gas sorption isotherms showed that mortars with a higher content of brick fragments particles exhibited a higher porosity and a greater BET surface area but a lower average pore diameter compared to mortars lacking this special aggregate.     

Determination of PNU 157706, a new dual inhibitor of 5alpha-reductase, in rat plasma by high-performance liquid chromatography with ultraviolet detection

The beta2-glycoprotein I (beta2GPI)-binding properties of five murine monoclonal antibodies immobilized as capture antibodies were studied using surface plasmon resonance detection. The monoclonal antibody with the fastest dissociation kinetics (6F3) was selected for the development of an immunoaffinity chromatography procedure, assuming that its behaviour would be similar in both systems since the covalent coupling chemistries involved amino groups in both cases. Under our experimental conditions of a fast one-step procedure, beta2GPI was purified to homogeneity from human plasma with a yield of about 50%. Beta2GPI was eluted under fairly mild conditions, either at low pH or at high pH. The immunoadsorbent was used five times without any apparent loss of binding capacity. The immunopurified protein showed similar binding to cardiolipin-coated polystyrene wells as beta2GPI purified by conventional methods. However, differences in the pattern of immunoreactivity in relation to the purification procedure were observed by surface plasmon resonance using the monoclonal antibody with the highest association kinetics (9G1) immobilized on the sensor surface.     

Effect of Continuous Cooling on Secondary Phase Precipitation in the Super Duplex Stainless Steel ZERON-100

The precipitation of secondary phases in super duplex stainless steels (SDSS) is a subject of great relevance owing to their dangerous effects on both mechanical and corrosion-resistance properties. This paper examines the effect of continuous cooling after solution annealing treatment on secondary phase precipitation in the ZERON-100 SDSS. It considers the influence of cooling rate on volume fraction, morphology and chemical composition. It has been found that the formation of sigma and chi phases can be avoided only at cooling rates higher than 0.7 °C/s. In addition, at the lowest cooling rate the sigma phase amount approaches the equilibrium value, but the chi phase amount remains significantly low.