Exergetic analysis of atomization process of liquid

The exergy balance equation for liquid atomization is discussed and exergetic efficiency of atomization is defined. On the basis of data taken from the literature some calculations of this efficiency have been carried out for the most widespread cases of atomization, i.e., for pressure and pneumatic atomization. The efficiency is low and does not exceed 1%. Some recommendations about how to carry out the full analysis of all items of the exergetic balance have been made. The results of such an analysis would give some indication of possible improvements in atomizer design and operating parameters.     

Effect of γ-alumina crystallinity on the state of rhodium during high-temperature treatments in oxygen and hydrogen

Rhodium catalysts, supported on six γ-Al₂O₃ supports with different crystallinities, were exposed to sequential treatments in hydrogen at 500°C, in oxygen at 760°C, in hydrogen at 500°C and at 760°C, respectively. Samples were characterized by X-ray diffraction and hydrogen chemisorption at various stages in the sequential treatment. Based on the characterization results, it is concluded that the formation of crystalline Rh₂O₃ is a function of γ-Al₂O₃ crystallinity; formation of crystalline Rh₂O₃ increased with increasing crystallinity of γ-Al₂O₃ during treatment in oxygen at 760°C. The crystalline Rh₂O₃ formed during treatment in oxygen at 760°C was reduced to Rh metal by hydrogen at 500°C, but most of the Rh did not adsorb hydrogen at room temperature. Subsequent treatment in hydrogen at 760°C increased the hydrogen adsorption capacity by as much as a factor of three. X-ray line broadening measurements showed that oxygen treatment of reduced Rh/γ-Al₂O₃ at 760°C followed by hydrogen reduction at 500°C resulted in significant increases in Rh crystal size; further treatment in hydrogen at 760°C resulted in additional sintering of Rh.     

The effect of copper ions on interaction of UV radiation with methacrylic matrix – EPR study

The role of metal ions introduced to polymer matrix in the photochemical degradation of material is not fully understood. In this paper, we considered the effect of copper ions on the photochemical changes in Methafilcon A after UV-irradiation. The presence of methacrylic acid in the structure of Methafilcon A increases the loading capacity of these ions. In result, there is observed the production much more radicals after UV-irradiation than in pure matrix, without copper ions. When the time of UV-exposure increases, the EPR signal of trapped Cu(II) ions in the material decreases. This proves the transformation of Cu(II) to a diamagnetic state of stable Cu(I)-intermediates or copper oxides. Simultaneously, in the first 5-min of UV-irradiation there is observed a rapid increase in intensity of the radical signal, which disappears when the exposure time is extended. This mechanism of radical generating is quite different than for Methafilcon A matrix without copper ions.     

Phenol‐Based Antioxidants and the In Vitro Methods Used for Their Assessment

Abstract: In recent years, much interest has been observed in the field of phenol‐based antioxidants. As a result of this, many analytical methods have been developed for the purpose of the quantification of phenolic and polyphenolic antioxidant capacities in biological materials. Many of these methods have been altered for application toward the in vitro assessment of antioxidant activities in animal and human model systems as well as in vivo. Due to the varied applicability and usage, methods for the assessment of phenol antioxidant capacities have become so widespread that they are often misused. It is the intent of this work to review the chemistry behind the antioxidant activity of phenolics as well as summarize the many methods applicable for the measurement of in vitro phenolic antioxidant capacity.     

The study of the interactions between graphene and Ge(001)/Si(001)

The interaction between graphene and germanium surfaces was investigated using a combination of microscopic and macroscopic experimental techniques and complementary theoretical calculations.Density functional theory (DFT) calculations for different reconstructions of the Ge(001) surface showed that the interactions between graphene and the Ge(001) surface introduce additional peaks in the density of states,superimposed on the graphene valence and conduction energy bands.The growth of graphene induces nanofaceting of the Ge(001) surface,which exhibits well-organized hill and valley structures.The graphene regions covered by hills are of high quality and exhibit an almost linear dispersion relation,which indicates weak graphene-germanium interactions.On the other hand,the graphene component occupying valley regions is significantly perturbed by the interaction with germanium.It was also found that the stronger graphene-germanium interaction observed in the valley regions is connected with a lower local electrical conductivity.Annealing of graphene/Ge(001)/Si(001) was performed to obtain a more uniform surface.This process results in a surface characterized by negligible hill and valley structures;however,the graphene properties unexpectedly deteriorated with increasing uniformity of the Ge(001) surface.To sum up,it was shown that the mechanism responsible for the formation of local conductivity inhomogeneities in graphene covering the Ge(001) surface is related to the different strength of graphene-germanium interactions.The present results indicate that,in order to obtain high-quality graphene,the experimental efforts should focus on limiting the interactions between germanium and graphene,which can be achieved by adjusting the growth conditions.     

Enzymatic modification of protein preparation obtained from water-washed mechanically recovered poultry meat

Studies were conducted on a protein preparation obtained from washed mechanically recovered poultry meat (MRPM). The effect of addition of 3 g/kg microbial transglutaminase (MTG) to poultry meat protein was evaluated in terms of texture changes by dynamic mechanical analysis (DMA) and nuclear magnetic resonance (NMR) to determine water content in the preparation and its effect on protein. Samples with the addition of MTG were pre-incubated at 5–6 °C for 1.5, 3, 4.5, 6, 7.5, 9 and 24 h. The largest changes for both texture parameters and rheological properties were observed in the interval of approx. 4–7 h incubation. The protein preparation with the enzyme added had significantly higher values of the moduli of elasticity (G₁) and losses (G₂) in comparison to the control system. Samples with the addition of MTG also showed a higher water-binding capacity. From the NMR studies it was found that the greatest amount of water was bound by protein in the period of approx. 2.5–5 h incubation. After that time an increase was found in the amount of free water in the sample, which suggests that it was displaced from the system by stronger protein–protein bonds.     

Shape optimization in oppositely directed coupled diffusion within composite structures

Some textile dressings contain the microcapsulated therapeutic substance. The diffusion of the activating agent (the exudate) from the wound through the material initiates the chemical reaction within microcapsules and releases the therapeutic agent. The semi-permeable membrane within the dressing reduces the diffusion of therapeutic agent to surrounding, whereas the exudate diffuses normally. The oppositely directed coupled diffusion is analyzed within 2D cross-section of dressing. State variables are both activating agent concentration and therapeutic substance concentration. State equations, boundary and initial conditions are determined. The sensitivity of an arbitrary functional is analyzed by means of direct and adjoint approaches and implemented into the problem of shape optimization. The objective functionals and the optimality conditions are formulated. Numerical example of 2D shape optimization is presented.