Analyzing the Causes of Crack Formation in Porcelain and the Ways to Eliminate Them

The studies deal with the porcelain products produced by casting finely-dispersed slips into gypsum molds. The causes of the occurrence of cracks on the edges of products after bisque and glazed firing were established and the ways of their elimination were proposed.As a result of the comprehensive research into the basic ceramic mass of the assigned composition and products from it, a series of the technological factors that cause cracking were determined.Determining the fineness of grinding of production slips of various batches showed that the residue on sieve No. 0063 ranged from 0.7 to 3.5 %. The direct correlation between the occurrence of cracks in products and an elevated indicator of the residue that contributed to the stratification of a ceramic slip in the process of settling in gypsum molds was established. This led to the emergence of internal stresses in the structure of a potsherd. It was established that another factor that caused cracking of products was the existence in the composition of the ceramic mass of large quartz grains, which in the heating-cooling process are capable of modification transformations. In addition, the low temperature of bisque firing did not contribute to the completion of the process of dehydration of clay and mica minerals, which strengthened the internal stresses in a potsherd.The research revealed that to ensure qualitative indicators of ceramic products, it is necessary not only to control the residue on a sieve but also to take into consideration the distribution of the fractional composition of a ceramic slip, while the content of the quartz component of 30–63 µm should not exceed 12 % by weight. This contributes to the formation of a dense homogeneous potsherd with a high content of a mullite phase.As a result of the research, it was also proposed to change the temperature of bisque firing from 660 to 800 °C. It is at this temperature that the processes of dehydration of layered silicates are completed and the shrinkage processes are stabilized.The obtained results can be applied at the typical production of household products from low-temperature porcelai

The Study of Influence of Natural Antioxidants on Quality of Peanut and Linseed Oil Blends During Their Storage

Influence of various natural antioxidants (oil extracts of sage and black currant leaves, garlic and hips) on in-storage quality of oils has been studied. Dynamics of the acid and peroxide numbers of fat of the developed oil samples was studied. Influence of natural antioxidants on preservation of polyunsaturated oleic, linoleic, linolenic fatty acids in peanut and linseed oil blends was established.When developing blended oils with an optimal fatty acid composition, it is advisable to use linseed oil which is characterized by a high content of ω-3 fatty acids. Since polyunsaturated fatty acids have a high degree of oxidation and degradation, they are unstable. This causes certain difficulties both in production and storage of vegetable oils and solving the problem of improving the product quality.It was established that the use of natural antioxidants affects preservation of quality of peanut and linseed blends, namely, organoleptic properties, acid and peroxide numbers of fat. It was proved that introduction of the studied oil extracts in an amount of 5 % increases the oxidation resistance of peanut and linseed oil blends by 1.2‒1.7 times.It was shown that to evaluate the effect of plant extracts on quality of the developed blends, it is expedient to use the content of polyunsaturated fatty acids as the main criterion. It was established that natural antioxidants contribute to preservation of 69.0‒73.0 % of linoleic acid, 73.5‒78.9 % of oleic acid and up to 82 % of linolenic acid from the initial content in peanut and linseed oil blends. The ratio of polyunsaturated fatty acids ω-6:ω-3 inall samples remained at the level of ratio of these acids in fresh blends, namely 4:1.The use of plant extracts in the formulations of peanut and linseed oil blends significantly slows down the processes of hydrolysis and self-oxidation which ensures in-storage preservation of consumer properties of new oils with an optimized fatty acid composition

New 5-Hydroxycoumarin-Based Tyrosyl-DNA Phosphodiesterase I Inhibitors Sensitize Tumor Cell Line to Topotecan

Tyrosyl-DNA-phosphodiesterase 1 (TDP1) is an important enzyme in the DNA repair system. The ability of the enzyme to repair DNA damage induced by a topoisomerase 1 poison such as the anticancer drug topotecan makes TDP1 a promising target for complex antitumor therapy. In this work, a set of new 5-hydroxycoumarin derivatives containing monoterpene moieties was synthesized. It was shown that most of the conjugates synthesized demonstrated high inhibitory properties against TDP1 with an IC50 in low micromolar or nanomolar ranges. Geraniol derivative 33a was the most potent inhibitor with IC50 130 nM. Docking the ligands to TDP1 predicted a good fit with the catalytic pocket blocking access to it. The conjugates used in non-toxic concentration increased cytotoxicity of topotecan against HeLa cancer cell line but not against conditionally normal HEK 293A cells. Thus, a new structural series of TDP1 inhibitors, which are able to sensitize cancer cells to the topotecan cytotoxic effect has been discovered