Fundamental Investigations on the High-Temperature Corrosion of Spinel-Forming Alumina Castables by Steel Slags

This study investigated the effect of the CaO/SiO2 mass ratio of steel slag on the corrosion behavior of spinel-forming alumina-based castables with a content of MgO (3–7 wt.%). Equiweight mixtures of castables and slags were calculated by FactSage, observed by HMTA, fired at 1350 °C, and investigated by XRD. From these results, we conclude that the presence of SiO2-rich phases accelerates the growth of the liquid phase in a narrow temperature range for the tested samples, which accelerates the degradation of castables. The static corrosion test was conducted by means of the coating method at 1450 °C. The corrosion index (IC) in the regions of castables affected by slags was calculated. Phases and phase distributions were evaluated by SEM-EDS. From these results, we conclude that for the slag with the lowest mass ratio of CaO/SiO2 (1.1), the reaction zone occurs only below the slag-refractory interface, which indicates the aggressive character of this slag.

Sc3Ir4Si13+x and Sc4Ir7Ge6 – the perovskite-related crystal structures

The crystal structure of Sc3Ir4Si13+x (x = 0.22) [space group P m 3 ‾ n $Pm‾{3}n$ , a = 8.4651(1) Å] is found to be a new disordered variant of the primitive cubic Yb3Rh4Sn13 Remeika prototype. The silicide is stable in the narrow temperature range of 1283–1397 °C and reveals metallic properties. The crystal structure of Sc4Ir7Ge6 [U4Re7Si6 type, space group I m 3 ‾ m $Im‾{3}m$ , a = 8.1397(8) Å] is refined for the first time. The electronic band structure calculations reveal that the properties of this germanide can be explained based on the free electron gas model. Both compounds reveal close structural relationships to the simple perovskite structure.

Investigation of the Fluxing Additives Effect on the Foaming of Different Silicate Raw Materials

The main trends in the use of silicate raw materials for the production of heat-insulating materials are considered. It is shown that the introduction of modifying additives-fluxes is promising to reduce the energy intensity of the technology. The substances that play the role of fluxes in the silicate industry are selected. The most active fluxes were chosen - sodium tetraborate Na2B4O7 (borax) and sodium fluoride NaF. The mechanism of their melting effect on the silicate mass is investigated. It is shown that both borax and sodium fluoride are active fluxes, intensifying the melting of silicate raw materials of all types. The use of fluoride is hampered by a narrow temperature range, in which the formation of a stable porous structure is possible.

Foam-Resilient Distillation Processes—Influence of Pentosan and Thermal Energy Input on Foam Accumulation in Rye Mash Distillation

Foaming of mashes during distillation is a common problem encountered in spirit drink production. It has a negative impact on the purity of the final product. This research article presents the key aspects of foam accumulation in rye mashes during distillation. Foam accumulation was influenced by substrate characteristics and process parameters. The experiments showed that pentosan levels and thermal energy input were the crucial parameters for foam accumulation in rye mashes. Foam accumulation was significantly enhanced by higher pentosan levels, due to the higher viscosity imparted by pentosan. Hence, degradation of pentosans prior to distillation presents a way to reduce foam accumulation. In terms of thermal energy input, foam accumulation was significantly lower when the thermal energy input was reduced from 400 to 200 W/L. Substantial foaming only occurred in a narrow temperature range of 89.5 to 98.2 C. The results allowed for the first time to make recommendations to prevent problematic foam accumulation during distillation of rye mashes.

Physical Aging Behavior of a Glassy Polyether

The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state.

Фотоиндуцированный магнитооптический эффект Керра в сульфиде европия EuS

The photoinduced magnetization in europium sulfide EuS was studied by the magneto-optical Kerr effect. It is experimentally established that when a sample is exposed to light with a photon energy greater than the band gap, photoinduced magnetization arises, associated with the formation of magnetic polarons with a large magnetic moment of about 3000 μB. The polarons are excited in a narrow temperature range of 12-18 K and form a superparamagnetic ensemble with an average polaron lifetime of 13 µs. An experimental setup for measuring photoinduced magnetization with the optical pump-and-probe method is described.

Полиморфизм ScBO-=SUB=-3-=/SUB=- при твердофазном синтезе из аморфных прекурсоров

Detailed X-ray studies of changes in the structure of ScBO3 in the process of successive isothermal annealing of the initial amorphous precursor were carried out. It was shown that, during successive annealing of an amorphous precursor, the crystalline phase is first formed at an annealing temperature of 710 ° C, the positions of the reflections of which do not coincide with the position of the reflections of the known calcite structure. This phase exists in a very narrow temperature range (~ 30 ° C) and with an increase in the annealing temperature to 750 ° C, it completely transforms into the known rhombohedral phase of calcite. Using the ENDEAVOUR software complex, the cell parameters, the positions of the atoms in the cell, and the space group of the symmetry of the new phase were determined. It turned out that the new phase corresponds to the hexagonal structure of vaterite (S.G. P63 / mmc), known for other rare-earth orthoborates (REM).

Enhanced thermoelectric properties of n-type Ti-doped PbTe

Thermoelectric (TE) generators, converting waste heat to electricity regain their attractiveness for reduction of fossil fuels’ reliance, and consequently minimizing adverse environmental effects. Such generators are based on an electrical series connection of TE couples, which consist n- and p- type semiconducting legs divided by metallic bridges. While for intermediate temperatures of up to 500°C, n-type PbTe was extensively studied and employed in commercial TE power generation applications, its maximal efficiency, as was reflected by the TE figure of merit, ZT, was in most of the cases maximized at a narrow temperature range for any given donor dopant concentration. The most commonly applied donor dopants are iodine and bismuth. Yet, some interesting characteristics were recently proposed upon using Ti as a donor dopant. Up to date an impressive maximal ZT of ∼1.2 was obtained at 500°C, upon doping of PbTe by 0.1 at.% Ti, while no lower concentrations were ever investigated. In the current research a lower, 0.05 at.% Ti doping level was applied, leading to the highest ever reported ZT values, for any given Ti doped PbTe, up to 350°C. Since the chemical compatibility of Ti with PbTe, as a metallic bridge in such couples, is well established, mainly due to its low diffusion rates, the potential of generating a stable Ti-doped functionally graded n-type PbTe material, with enhanced TE performance, is currently being proposed.

Oxygen, temperature and the deep-marine stenothermal cradle of Ediacaran evolution

Ediacaran fossils document the early evolution of complex megascopic life, contemporaneous with geochemical evidence for widespread marine anoxia. These data suggest early animals experienced frequent hypoxia. Research has thus focused on the concentration of molecular oxygen (O 2 ) required by early animals, while also considering the impacts of climate. One model, the Cold Cradle hypothesis, proposed the Ediacaran biota originated in cold, shallow-water environments owing to increased O 2 solubility. First, we demonstrate using principles of gas exchange that temperature does have a critical role in governing the bioavailability of O 2 —but in cooler water the supply of O 2 is actually lower. Second, the fossil record suggests the Ediacara biota initially occur approximately 571 Ma in deep-water facies, before appearing in shelf environments approximately 555 Ma. We propose an ecophysiological underpinning for this pattern. By combining oceanographic data with new respirometry experiments we show that in the shallow mixed layer where seasonal temperatures fluctuate widely, thermal and partial pressure ( p O 2 ) effects are highly synergistic. The result is that temperature change away from species-specific optima impairs tolerance to low p O 2 . We hypothesize that deep and particularly stenothermal (narrow temperature range) environments in the Ediacaran ocean were a physiological refuge from the synergistic effects of temperature and low p O 2 .

Imparting Photo-responsive Function to Thermo-responsive Iridescent Emulsions

In our previous paper, we reported that thermo-responsive emulsions can be prepared based on a long-chain amidoamine derivative (C18AA) and tetraoctylammonium bromide (TOAB), and that the C18AA + TOAB emulsions developed a characteristic interference color in a narrow temperature range. However, the coloration of the original C18AA + TOAB at room temperature exhibited poor brightness. In the present study, we show that the addition of NaOH is effective in both lowering the coloration temperature and improving the brightness of C18AA + TOAB emulsion considerably. Furthermore, we demonstrate that photo-response function can be imparted to C18AA + TOAB iridescent emulsions by introducing a photochromic naphthopyran derivative (Pyran) that reversibly changes from white to yellow upon UV irradiation. The C18AA + TOAB emulsions containing Pyran shows a dual stimuli-responsive iridescent property, and the emulsion color is controllable and reversible through both UV irradiation and temperature.