Тишакова Татьяна Станиславовна канд хим н., ассистент; Левашова Ольга Леонидовна канд фарм н., ассистент; Савельева Елена Валерьевна ассистент. В сборнике представлены тезисы
VANADINITE Maurelio Vicente Augusto, group 20. Scientific adviser is Svetlana Kozub
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VANADINITEMaurelio Vicente Augusto, group 20. Scientific adviser is Svetlana KozubVanadinite is an uncommon mineral, belonging to the apatite group of phosphates, with stunning bright-red and orange crystals that are perfectly formed. Vanadinite is especially found in association with the lead. It is considered to be common known (popular) and it has very high demand. It was originally discovered in Mexico by the Spanish mineralogist Andrés Manuel del Río in 1801. He called the mineral "brown lead". Vanadinite deposits have since been unearthed in South America, Europe, Africa, and in other parts of North America. Vanadium is also a micronutrient found naturally in Food rich in vanadium: radishes, eggs, buckwheat, mushrooms, shellfish and oats. Vanadinite is in the apatite group of phosphates, with the chemical formula Pb5(VO4)3Cl. It is composed (by weight) of 73.15% lead, 10.79% vanadium, 13.56% oxygen, and 2.50% chlorine. It has a molar mass of 1416.27 g/mole. Whereas most chemical series involve the substitution of metallic ions, this series substitutes its anion groups; phosphate (PO4), arsenate (AsO4) and vanadate (VO4). Common impurities of vanadinite include phosphorus, arsenic and calcium. Each structural unit of vanadinite contains a chlorine ion surrounded by six divalent lead ions at the corners of a regular octahedron, with one of the lead ions provided by an adjoining vanadinite molecule. Each vanadium atom is surrounded by four oxygen atoms at the corners of an irregular tetrahedron. Crystals of vanadinite conform to a hexagonal system of symmetry. Vanadinite is one of the main industrial surces of the element vanadium, which can be extracted by roasting and smelting. Vanadinite is also occasionally used as a source of lead. Approximately 85% of vanadium produced is used as ferrovanadium or as a steel additive, resulting in a significant increase in the strength of the steel. Or it canbe used as a catalyst in manufacturing sulfuric acid and for protecting steel against corrosion. It plays a role in cellular metabolism, the formation of bones and teeth, reproduction, and growth. For absorption using the same means of transport iron. Vanadium is used for treating diabetes, low blood sugar, high cholesterol, heart disease, tuberculosis, syphilis, a form of “tired blood” (anemia), and water retention (edema); for improving athletic performance in weight training; and for preventing cancer. There is some evidence that vanadium might act like insulin, or help to increase the effects of insulin. Unfortunately, vanadium's effects are not all positive. Vanadium works by blocking dozens of enzymes. Researchers have discovered several disturbing effects form vanadium, including damage to DNA, oxidation of lipids, which is considered a primary step in the development of cardiovascular disease, have been found to kill beta cells! Some researchers speculate that excess vanadium could also be involved in several diseases of the kidney and bone. Under normal conditions, the body contains 20 to 25 mg. of vanadium, and the average diet supplies about 2 mg. of vanadium per day. CALCITEAhmed Gabala, group 21. Scientific adviser is Tatyana TishakovaCalcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380–470°C. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, prisms, or various scalenohedra. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form. Its fracture is conchoidal, but difficult to obtain. It has a defining Mohs hardness of 3, a specific gravity of 2.71, and its luster is vitreous in crystallized varieties. Color is white or none, though shades of gray, red, orange, yellow, green, blue, violet, brown, or even black can occur when the mineral is charged with impurities. High-grade optical calcite was used in World War II for gun sights, specifically in bomb sights and anti-aircraft weaponry. Also, experiments have been conducted to use calcite for a cloak of invisibility. Microbiologically precipitated calcite has a wide range of applications, such as soil remediation, soil stabilization and concrete repair.The largest documented single crystals of calcite originated from Iceland, measured 7×7×2 m and 6×6×3 m and weighed about 250 tons. Calcite is a common constituent of sedimentary rocks, limestone in particular, much of which is formed from the shells of dead marine organisms. Approximately 10% of sedimentary rock is limestone. Calcite is the primary mineral in metamorphicmarble. It also occurs as a vein mineral in deposits from hot springs, and it occurs in caverns as stalactites and stalagmites. Calcite forms from a poorly ordered precursor (amorphous calcium carbonate, ACC). The crystallization process occurs in two stages; firstly, the ACC nanoparticles rapidly dehydrate and crystallize to form individual particles of vaterite; secondly, the vaterite transforms to calcite via a dissolution and reprecipitation mechanism with the reaction rate controlled by the surface area of calcite. The second stage of the reaction is approximately 10 times slower than the first. However, the crystallization of calcite has been observed to be dependent on the starting pH and presence of Mg in solution.
Mustapha El Hamdi, group 21. Scientific adviser is Tatyana TishakovaAragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO (the other form being the mineral calcite). It is formed by biological and physical processes, including precipitation from marine and freshwater environments. Aragonite's crystal lattice differs from that of calcite, resulting in a different crystal shape, an orthorhombic system with acicular crystals. Repeated twinning results in pseudo-hexagonal forms. Aragonite may be columnar or fibrous, occasionally in branchingstalactitic forms called flos-ferri ("flowers of iron") from their association with the ores at the Carinthian iron mines. The type location for aragonite is Molina de Aragón (Guadalajara, Spain), 25 km from Aragon for which it was named in 1797.An aragonite cave, the Ochtinská Aragonite Cave, is situated in Slovakia. In the USA, aragonite in the form of stalactites and "cave flowers" (anthodite) is known from Carlsbad Caverns and other caves. Massive deposits of oolitic aragonite sand are found on the seabed in the Bahamas. Aragonite forms naturally in almost all mollusk shells, and as the calcareous endoskeleton of warm- and cold-water corals (Scleractinia). Several serpulids have aragonitic tubes. Because the mineral deposition in mollusk shells is strongly biologically controlled, some crystal forms are distinctively different from those of inorganic aragonite. In some mollusks, the entire shell is aragonite; in others, aragonite forms only discrete parts of a bimineralic shell (aragonite plus calcite). Aragonite also forms in the ocean and in caves as inorganic precipitates called marine cements and speleothems, respectively. The nacreous layer of the aragonite fossil shells of some extinct ammonites forms an iridescent material called ammolite. Aragonite is metastable and is thus commonly replaced by calcite in fossils. Aragonite older than the Carboniferous is essentially unknown. Aragonite is thermodynamically unstable at standard temperature and pressure, and tends to alter to calcite on scales of 107 to 108 years. The mineral vaterite, also known as μ-CaCO3, is another phase of calcium carbonate that is metastable at ambient conditions typical of Earth's surface, and decomposes even more readily than aragonite. In aquaria, aragonite is considered essential for the replication of reef conditions in aquariums. It not only is the material that the sea life is evolved to use and live around, but also keeps the tank's pH close to its natural level.
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