Gd-Bi-M-Ce-O (M = Cu,Zr, Ni,Co, Mn) ceria-based solid solutions for low temperature CO oxidation

Ceria based solid solutions doped by Gd, Bi, and the third dopant were synthesized by the co-precipitation method with ultrasonic treatment, followed by calcination at the temperature of 500°С. Characterization of the synthesized nanosystems by XRD, TEM, TG, Raman spectroscopy, FTIR, XPS was carried out. It is shown that all obtained powders of solid solutions crystallized into a cubic structure of the fluorite type, with an average particle size of 5–15 nm. The samples had a mesoporous structure of the pore diameter of 2–5 nm. The catalytic activity of Gd-Bi-M-Ce-O (M = Cu, Zr, Ni, Co, Mn) solid solutions was carried out. The catalyst Gd_0.05Bi_0.15Mn_0.20Ce_0.60O₂ has the lowest oxidation temperature.     

Light stability in cyan and magenta tones using standard and highly chromatic toner particles

An increasing requisite regarding the reproduction quality of electrophotographic printing machines demands improvement of new electrophotographic toner formulation, especially used pigments. The subject of this paper is a comparison of prints realised by depositing high chroma (HC) and standard emulsion aggregation (EA) toner on gloss fine art paper. HC toner has a different composition of the cyan and magenta tones compared with the corresponding standard EA toner tones and therefore behaves differently under real conditions. The patches used for this experiment were cyan and magenta tone prints with tone values (TVs) of 0, 20, 60 and 100%. Ultraviolet (UV) degradation was measured over time intervals of 0, 6, 12, 24, 48, 96, 144 and 240 h for all patches. Results (laboratory values) were calculated using colorimetric difference. Values were plotted as a function of time in tonal degradation graphs. A model was created using non‐linear regression‐based modelling. The experiment demonstrates that magenta patches are more susceptible to degradation in comparison with cyan patches. With the increase in tonal value, it is noticeable that the colorimetric difference is higher. Colorimetric differences calculated using HC magenta toner and standard EA cyan toner (100% TV) were higher than ?E = 5, starting to appear after 6 h of exposure to UV radiance. After 12 h of exposure, colorimetric differences of standard magenta tones that were greater than ?E = 5 also started to appear. Cyan patches (100% TV) printed with HC toner were more stable than the other patches, and after 240 h of exposure had not crossed the boundary of ?E = 5.     

Production of stable amorphous form by means of spray drying

Spray drying is a very useful method for manufacturing of amorphous solid materials. This is mainly due to the possibility of fast solvent evaporation that leads to a rapid transformation of solution to a solid state. Besides evaporation kinetics, there are various process parameters that influence physical and chemical characteristics of such obtained material. The possibility of obtaining a stable amorphous structure of the active pharmaceutical ingredient in a spray dryer was examined. A solution of the hydrochloride crystalline structure of the active pharmaceutical ingredient in a mixture of water and acetonitrile was dried at different temperatures and flowrates of nitrogen used for atomization, as well as the flowrates of the solution. The influence of the process conditions on the properties of the product was analyzed. The final dried products were characterized and identified with a variety of analytical and physical methods. The results showed that a stable amorphous structure of the high purity active pharmaceutical ingredient is obtained, and that the optimal conditions of the process are defined. The amorphous structure is stable at temperatures below 200°C when it is transformed into a new crystal structure. Conditions of high relative air humidity lead to partial transformation.     

Special Important Aspects of the Thomson Effect

A comprehensive study of the mechanisms of heating and cooling originating from an electrical current in semiconductor devices is reported. The variation in temperature associated with the Peltier effect is not related to the presence of heat sources and sinks if the heat flux is correctly determined. The Thomson effect is commonly regarded as a heat source/sink proportional to the Thomson coefficient, which is added to the Joule heating. In the present work, we will show that this formulation of the Thomson effect is not sufficiently clear. When the heat flux is correctly defined, the Thomson heat source/sink is proportional to the Seebeck coefficient. In the conditions in which the Peltier effect takes place, the temperature gradient is created, and, consequently, the Thomson effect will occur naturally.     

Binary monkey algorithm for approximate packing non-congruent circles in a rectangular container

A Packing problem consists in the best arrangement of several objects inside a bounded area named as the container. This arrangement must fulfill with technological constraints, for example, objects should not be overlapping. Some packing models for circular objects are typically formulated as non-convex optimization problems; where the continuous variables are the coordinates of the objects, so they are limited to not finding optimal solutions. Due to the combinatorial nature in the arrangement of such objects, heuristic methods are being used extensively which combine methods of global search and methods of local exhaustive search of local minima or their approximations. In this paper, we will address the packing problem for non-congruent (different size) circles with the binary version of the monkey algorithm which incorporates a cooperation process and a greedy strategy. We use a rectangular grid for covering the container. Every node in the grid represent potential positions for a circle. In this sense, binary monkey algorithm for the knapsack problem, can be used to solve de 0–1 approximate packing problem for non-congruet circles. The binary monkey problem uses two additional processes of the original monkey algorithm, these two processes are a greedy process and a cooperation processes.

     

Nonclassical relaxation oscillations in neurodynamics

A modification of the well-known FitzHugh–Nagumo model from neuroscience has been proposed. This model is a singularly perturbed system of ordinary differential equations with a fast variable and a slow variable. The existence and stability of a nonclassical relaxation cycle in this system have been studied. The slow component of the cycle is asymptotically close to a discontinuous function, while the fast component is a δ-like function. A one-dimensional circle of unidirectionally coupled neurons has been considered. The existence of an arbitrarily large number of traveling waves for this chain has been shown. In order to illustrate the increase in the number of stable traveling waves, numerical methods were involved.     

The Effect of Titanium, Zirconium and Tin on the Growth of Diatom Synedra Acus and Morphology of Its Silica Valves

The effect of three Group IV metals (titanium, zirconium and tin) on the growth, morphology and chemical composition of the freshwater diatom Synedra acus subsp. radians (Kützing) Skabichevsky was studied and compared with germanium. The elements in their highest oxidation states were introduced into the culture medium in the form of hydroxides. Germanium was found to be toxic at ??5?mol. % of the total Ge-Si content in the culture medium. In the presence of other elements, a slight decrease in the cell division rate was observed independent of the element within 1?C15% content interval. The analysis of the obtained biomass and silica valves revealed the presence of all the added elements within the cells. However, only germanium was incorporated into the valves in considerable amounts. S. acus cultivation with the addition of 5% Group IV elements resulted in cells having the following aberrations in the structure of the silica valves: changes in valve shape, thickening of valves, alterations of the areolae rows, irregularity or absence of the areolae and a decrease in the mechanical strength of valves. Moreover, the effect of Group IV elements on silica formation was simulated in vitro using a synthetic polymer bearing polyamine and phosphate groups found in silaffines (proteins from diatom frustules). The studied elements were observed to provoke the formation of unstable silica particles in solution. We propose that the observed effects of germanium, titanium, zirconium and tin on diatom growth and structure are due to uncontrollable silica condensation.