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Abstrakt

An emerging ultrasonic technology aims to control high-pressure industrial processes that use liquids at pressures up to 800 MPa. To control these processes it is necessary to know precisely physicochemical properties of the processed liquid (e.g., Camelina sativa oil) in the high-pressure range. In recent years, Camelina sativa oil gained a significant interest in food and biofuel industries. Unfortunately, only a very few data characterizing the high-pressure behavior of Camelina sativa oil is available. The aim of this paper is to investigate high pressure physicochemical properties of liquids on the example of Camelina sativa oil, using efficient ultrasonic techniques, i.e., speed of sound measurements supported by parallel measurements of density. It is worth noting that conventional low-pressure methods of measuring physicochemical properties of liquids fail at high pressures. The time of flight (TOF) between the two selected ultrasonic impulses was evaluated with a cross-correlation method. TOF measurements enabled for determination of the speed of sound with very high precision (of the order of picoseconds). Ultrasonic velocity and density measurements were performed for pressures 0.1–660 MPa, and temperatures 3–30XC. Isotherms of acoustic impedance Za, surface tension #27; and thermal conductivity k were subsequently evaluated. These physicochemical parameters of Camelina sativa oil are mainly influenced by changes in the pressure p, i.e., they increase about two times when the pressure increases from atmospheric pressure (0.1 MPa) to 660 MPa at 30XC. The results obtained in this study are novel and can be applied in food, and chemical industries.
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This paper presents the results of experimental drum granulation of silica flour with the use of wetting liquids with different values of surface tension. Additionally, different liquid jet breakup and different residual moisture of the bed were applied in the tests. The process was conducted periodically in two stages: wetting and proper granulation, during which no liquid was supplied to the bed. The condition of the granulated material after the period of wetting (particle size distribution and moisture of separate fractions) and a change in the particle size distribution during the further conduct of the process (granulation kinetics) were determined.
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Measurements of dynamic surface tension were carried out in aqueous systems (water or 0.1 mM Triton X-100) comprising nanoparticles formed from chemically modified polyaldehyde dextran (PAD). The nanostructures, considered as potential drug carriers in aerosol therapy, were obtained from biocompatible polysaccharides by successive oxidation and reactive coiling in an aqueous solution. The dynamic surface tension of the samples was determined by the maximum bubble pressure (MBP) method and by the axisymmetric drop shape analysis (ADSA). Experiments with harmonic area perturbations were also carried out in order to determine surface dilatational viscoelasticity. PAD showed a remarkable surface activity. Ward-Tordai equation was used to determine the equilibrium surface tension and diffusion coefficient of PAD nanoparticles (D = 2.3×10-6 m2/s). In a mixture with Triton X-100, PAD particles showed co-adsorption and synergic effect in surface tension reduction at short times (below 10 s). Tested nanoparticles had impact on surface rheology in a mixed system with nonionic surfactant, suggesting their possible interactions with the lung surfactant system after inhalation. This preliminary investigation sets the methodological approach for further research related to the influence of inhaled PAD nanoparticles on the lung surfactant and mass transfer processes in the respiratory system.
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Abstrakt

The production process of prosthetic restorations runs in two stages. In the first stage, the prosthetic foundation is produced of metal alloys. In the second stage, a facing material is applied on the produced element. In both stages, the wettability is significantly important, as well as the free surface energy relating to it. The quality of the obtained cast depends on the surface phenomena occurring between the metal alloy and the material of which the casting mould is made. The performed examinations also point to a relation between the ceramics joint and the base, depending on the wetting angle. The aim of the presented paper was to examine influence of the composition of a Ti(C,N)-type coating on bases made of the Ni-Cr prosthetic alloy on the wettability and the surface free energy. The test material were disks made of the Ni-Cr alloy with the diameter of 8 mm. The disks were divided into five groups, which were covered with Ti(C,N) coatings, with different amounts of C and N in the layer. In order to determine the surface free energy (����), the wetting angle was measured. Two measure liquids were applied: distilled water and diiodomethane. The obtained results of the measurements of the water-wetting angles suggest that together with the increase of the ratio of nitrogen to carbon in the Ti(C,N) coating, the surface hydrophobicity increases as well. In all the samples, one can see a large difference between the energy values of the polar and the apolar components. The high values of the polar components and the low values of the apolar ones make it possible to conclude that these surfaces exhibit a greater affinity to the polar groups than to the apolar ones. On the basis of the analysis of the surface free energy, one can state that covering the alloy with Ti(C,N)-type coatings should not decrease the adhesion of the ceramics to the alloy, whereas TiC coatings should lead to the latter’s improvement. Due to their hydrophilicity, TiC coatings should decrease the adhesion of bacteria to the surface and hinder the formation of a bacterial biofilm.
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Abstrakt

Determination of the physico-chemical interactions between liquid and solid substances is a key technological factor in many industrial processes in metallurgy, electronics or the aviation industry, where technological processes are based on soldering/brazing technologies. Understanding of the bonding process, reactions between materials and their dynamics enables to make research on new materials and joining technologies, as well as to optimise and compare the existing ones. The paper focuses on a wetting force measurement method and its practical implementation in a laboratory stand – an integrated platform for automatic wetting force measurement at high temperatures. As an example of using the laboratory stand, an analysis of Ag addition to Cu-based brazes, including measurement of the wetting force and the wetting angle, is presented.
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