Suchergebnisse

"Electrostatic painting is the fastest and most efficient technology through industrial paints due to its impact on the environment, and also for its very easy application on different surfaces. The first and most important stage of the electrostatic painting is to clean the surface to be painted by removing the dirt, lubricants, oils, metal oxides or welding residues. In order to increase the efficiency of carbon steel surface cleaning, the influence of alkali and surfactant concentrations, temperature and stirring was investigated. To produce a uniform surface required for the electrostatic painting, some degreased samples were subjected to pickling operation using aqueous HCl solution. Keywords: carbon-steel, degreasing, pickling, ultrasonication "

"The origin of resistance and its relation to the superconducting mechanism remain a profound, unsolved mystery. Currently, model parameters used to fit normal state properties are specific and vary arbitrarily from one doping. This short review illustrates the electrical resistivity of ceramic high temperature superconductors copper oxides. The article gives a summary of the prevailing arguments of researchers to relate the material to ceramic HTS compounds. Keywords: superconductivity, HTC ceramic compounds, resistivity. "

"The Co11Zr2 magnetic phase was obtained by a combination of melting, mechanical milling and high temperature annealing. The structure and magnetic properties of the obtained material were investigated. Even though the samples possessed low coercivity, it was shown that they possess uniaxial anisotropy. Keywords: hard magnetic materials, magnetic anisotropy, mechanical milling, high temperature annealing "

Novel indolizines and pyrrolo[1,2-c]pyrimidines bearing a 3-carbonylchromen-2-one moiety on the pyrrole rings were synthesized and spectroscopic properties of some of synthesized compounds were investigated. Synthetic procedures started from 4-substituted pyrimidines, 3-(2-bromoacetyl)-2H-chromen-2-one and electron-deficient alkynes via 3+2 dipolar cycloaddition of cycloimmonium-ylides, generated in situ from their corresponding quaternary salts, in the presence of an epoxide playing the role of acid scavenger and reaction solvent. The structures of novel compounds were confirmed by chemical analyses, IR and NMR spectroscopy. Spectroscopic properties of some of the synthesized compounds were investigated.

The article presents a classification methodology of regional development in Romania (41 counties and Bucharest) using a set of data registered in 2019 by the National Institute of Statistics. Several indicators cover information related to the population (the migration, permanent residence, and education), local investments, private turnover, and investments in water supply and sewerage systems, including waste management. After applying the statistical tests, the separation of the counties was done in three classes, the delimitation indicating a high percentage of 59.5% of regions that have low values of the selected indicators. These regions require major investments that will lead to rising living standards, and the emergence of new jobs, driving down the average age of the population. 21.4% of the regions present an average level of the analyzed indicators while only 19% registered the highest values of the parameters, indicating urban agglomerations and a high level of industrial development.