Chemical Processes During Energy‐Saving Preparation of Lightweight Ceramics

Lightweight glass‐ceramic material similar to foam glass was obtained at 700°C–800°C directly from alkali‐activated silica clay and zeolitized tuff without preliminary glass preparation. It was characterized by low bulk density of 100–250 kg/m³ and high pore size homogeneity. Chemical processes occurring in alkali‐activated silica clay and zeolitized tuff were studied using X‐ray diffraction, thermal gravimetry, IR‐spectroscopy, and scanning electron microscopy. Pore formation in both compositions is caused by dehydration of hydrated sodium polysilicates (Na₂O·mSiO₂·nH₂O), formed during alkali activation. Additional pore‐forming gas source in alkali‐activated zeolitized tuff is trona, Na₃(CO₃)(HCO₃)·2H₂O, formed during interaction between unbound NaOH and CO₂ and H₂O from air. Influence of mechanical activation of raw materials on chemical processes occurring in alkaline compositions was also studied.     

Sewage sludge digestion at increased micropollutant content

Research was conducted, which aim was to evaluate quantitative and qualitative PCB changes in sewage sludge during mesophilic digestion, and the influence of those compound concentration above acceptable level (1.9 mg kg⁻¹ of sludge dry matter), also nickel and cadmium ions, on mesophilic digestion process. Before and after the digestion, concentration of seven PCB congeners, Ni and Cd in particular chemical fractions of the sludge was analyzed.     

Electrochemical behaviour of cationic polyelectrolytes at a polarized liquid/liquid interface

The behaviours of several cationic polyelectrolytes (chitosan; polyquaternium-4; diethylaminoethyl dextran; polyquaternium-10, and aminoacrylmethacrylate copolymer, Eudragit^® E100) at a polarised liquid/liquid interface are analysed and compared in the present paper. Based on the analysis of the voltammetric results, it was possible to determine some of the relationships between polymer structure and the tendency to adsorb at the interface. It was also possible to determine the substitution degree of a polymer comprising a chitosan main chain modified with glycidyltrimethylammonium chloride, and the values obtained are in agreement with those calculated using other methodologies. Finally, we report a comparative study concerning the effect of cationic (chitosan) and anionic (dextran sulphate) polyelectrolytes on the compactness of a phospholipid film.     

Diffusion welding of aluminium alloy strengthened by Al2O3 particles through an Al/Cu multilayer foil

In the diffusion welding (DW) of difficult-to-deform materials (such as composites and intermetallics), the application of intermediate multilayer foils (MF), which have alternating layers of elements that form intermetallics, allows for production of a permanent joint under milder conditions. In this paper, the processes occurring in the joint zone (JZ) during DW of Al–5 wt.%Mg+27 wt.%Al₂O₃ composite material through the Al/Cu interlayer were studied. It was shown that, while heating of such a foil, phase transformations that are due to the reaction diffusion of elements, run in it. At MF heating under a continuously applied external load, the materials are plastically deformed. It is established that the intensity of foil plastic deformation at a specified load non-monotonically depends on temperature. It is shown that welding temperature is determined by the temperature at which MF can undergo superplastic flow under the impact of applied pressure. A mechanism of formation for a solid-phase joint of high-strength materials through interlayers based on the MF of intermetallic-forming elements is proposed.     

Melanocyte pigmentation stiffens murine cardiac tricuspid valve leaflet

Pigmentation of murine cardiac tricuspid valve leaflet is associated with melanocyte concentration, which affects its stiffness. Owing to its biological and viscoelastic nature, estimation of the in situ stiffness measurement becomes a challenging task. Therefore, quasi-static and nanodynamic mechanical analysis of the leaflets of the mouse tricuspid valve is performed in the current work. The mechanical properties along the leaflet vary with the degree of pigmentation. Pigmented regions of the valve leaflet that contain melanocytes displayed higher storage modulus (7–10 GPa) than non-pigmented areas (2.5–4 GPa). These results suggest that the presence of melanocytes affects the viscoelastic properties of the mouse atrioventricular valves and are important for their proper functioning in the organism.     

Stability of emulsions formulated with high concentrations of sodium caseinate and trehalose

Stability of emulsions formulated with 10 wt.% oil (concentrated fish oil, CFO, sunflower oil, SFO, or olive oil, OO), sodium caseinate concentrations varying from 0.5 to 5 wt.%, giving oil-to-protein ratios of 20–2, and 0, 20, 30 or 40 wt.% aqueous trehalose solution was studied by Turbiscan. Particle size distribution, microstructure, and small angle X-ray scattering (SAXS) patterns were also obtained. The main mechanism of destabilization in a given formulation strongly depended on oil-to-protein ratio. As evidenced by the BS-profile changes with time, emulsions formulated with 0.5 and 1 wt.% NaCas destabilized mainly by creaming while for the 2 wt.% NaCas concentration, both creaming and flocculation mechanisms, were involved. The main destabilization mechanism for the 3, 4 or 5 wt.% NaCas emulsions was flocculation. Stability of emulsions was also affected by the content of trehalose in the aqueous phase. Trehalose diminished the volume-weighted mean diameter (D_4,3) and greatly improved stability.     

Net-value of the relativistic crystal field effect

The relativistic crystal field theory in case of the rare earth ion doped materials is presented. In order to calculate the values of crystal field splittings the effectively relativistic crystal field operators are applied. The matrix elements of these operators are evaluated in the non-relativistic LS scheme, whereas the radial integrals include one electron Dirac–Fock wavefunctions. The numerical results of the relativistic crystal field effects are presented for Ce³⁺ or Yb³⁺ ions in LuPO₄, and they are compared with those obtained from the non-relativistic approach.