Preparations for inhibiting crystal formation in wine

Потеря растворимости виннокислых солей калия и кальция является причиной выпадения кристаллического осадка в вине. Одним из способов стабилизации вин является внесение высокомолекулярных веществ в готовый к розливу продукт. Коллоидные вещества не препятствуют образованию ядер кристаллизации битартрата калия, но обладают ингибирующим действием по отношению к росту кристаллов. В то же время предлагаемые вещества имеют особенности, которые необходимо учитывать при выборе схемы обработки: метавинная кислота эффективна для всех типов вин, однако сохраняет свои свойства непродолжительное время; КМЦ наибольшее действие проявляет в белых винах, при этом может спровоцировать выпадение фенольных веществ в красных винах; маннопротеины не отличаются стабильным результатом. Гуммиарабик проявляет протекторные свойства не только в отношении фенольных веществ, но и эффективно блокирует рост кристаллов битартрата калия. Защитное действие гуммиарабика и полиаспартата калия недостаточно освещено в научной литературе, что обусловливает необходимость дальнейших исследований в экспериментальных и производственных условиях. Loss of solubility of tartaric salts of potassium and calcium is the cause of precipitation of crystal sediment in wine. One of the ways to stabilize wines is to introduce high-molecular substances into the product ready for bottling. Colloidal substances do not prevent the formation of crystallization center of potassium bitartrate, but possess an inhibitory effect on the growth of crystals. At the same time, the proposed substances offer properties that must be taken into account when choosing a treatment scheme: metatartaric acid is effective for all types of wines, but retains its properties for a short period of time; CMC demonstrates maximum effect in white wines, while it can provoke the sedimentation of phenolic substances in red wines; mannoproteins do not show steady result. Arabic gum shows protective properties not only in relation to phenolic substances, but also effectively blocks the growth of potassium bitartrate crystals. The protective effect of arabic gum and potassium polyaspartate is not sufficiently covered in the scientific literature, which necessitates further research in experimental and industrial conditions.

Crystallization of metals and alloys. Problem. Solutions

For a solution of the problem of crystallization of metals and alloys it is necessary to take for granted that the basic construction elements in forming crystals are nanocrystals of phases. Specific interphase surface energy of a crystallization center is directly proportional to its radius. Hydrogen exerts direct impact on process of crystallization of dendritic crystals of phases.

Chemical aspects of the process of concrete cracks elimination with the help of bacteria

The article describes the chemical processes of biogenesis of calcium carbonate for self-healing of concrete, taking into account four main factors: the concentration of calcium, the concentration of soluble inorganic carbon, the pH value, the presence of the crystallization center. A number of bacteria that can be found in soil, sand and natural minerals have the ability to release calcium carbonate, both in natural and laboratory conditions. In the laboratory, calcium lactate (CaC6H10O6) was used as a starting material for the formation of calcium carbonate. In addition, urea necessary for bacteria as a source of urease enzyme and yeast extract as a source of carbon and nitrogen were added. The resulting pH was brought to 9 to avoid possible chemical deposition of calcium carbonate. To improve the production technology of biological concrete, specially selected bacteria of the genus Bacillus with a combination of nutrients were used to create a reducing agent in concrete. With the help of such self-healing concrete by means of bacteria, cracks more than 100 µm wide can be compacted. With this approach, the bacteria in the alkaline medium convert CO2 into carbonate ions, which then interact with the Ca ions from the concrete matrix. This leads to the formation of calcium carbonate crystals. In addition, CO2 directly reacts with the calcium hydroxide matrix, which leads to the formation of calcite precipitate. The appearance of calcium carbonate crystals of large size with the participation of bacteria incorporated into the self-healing concrete provides an excellent ability to self-healing compared to traditional or developed environmentally unsafe self-healing cement materials. That is why this area of research is a promising alternative to environmentally hazardous methods of repair using cement.