The correlations between structures and mechanical characteristics of α-AlB12-, AlB12C2-, B4C-based lightweight ceramics and composites synthesized or sintered by hot pressing (at 30 MPa) and ...SiC-based ceramics obtained by reactive sintering are compared. The effect of C, TiC and SiC additions on the properties of the resultant composites and the particularities of the ceramics destruction under shock loading are discussed. Ballistic tests performed on 10 mm thick plates fabricated from the developed ceramics (2.63 g/cm3 density; 78 wt% B4C and 22 wt% SiC composition according to X-ray diffraction analysis; B3.64CSi0.01 and SiC1.07 stoichiometry according to SEM microprobe X-ray analysis), showed that the material could withstand a 10 m distance shot using a bullet with initial kinetic energy of 3.7 kJ.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Developed are projects of State Standards of Ukraine referring to determination of bromide, iodide, and nitrate ions in waters of different types. The method of determination of bromide,ions is based ...on registration of reflection spectra of products of bromination of phenol red, iodide ions—on the oxidation of the latter to iodine, its gas extraction to the solution of luminol and registration of chemiluminescence in the flow of carrier gas, nitrate ions—on chemiluminescence after reduction of nitrates to nitrites and gas extraction of nitrogen dioxide to the solution of luminol. The methods make it possible to determine bromide ions within the interval 0.02–0.5, iodide ions—0.006–0.5, nitrate ions—0.05–10 mg/dm
3
. A special attention is given to the study of interfering impact of water components and methods to remove it.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Photometric technique has been developed for determination of bromide ions in waters; the technique is based on oxidation in an aqueous solution of bromide to bromine by chloramine T, concentration ...of bromine–derivative fuchsine basic on membrane filters and measurement of lightness of obtained colored concentrates in a thin layer by means of reflection colorimetry. The detection limit of bromide–ions constitutes 10 μg/dm
3
, the linearity of the calibration curve ranges from 10 to 1000 μg/dm
3
. The excess of chloramines T does not interfere with determination, which simplifies and reduces the analysis. The proposed technique is more sensitive, fast and simple in execution than existing standard techniques. It makes it possible to control the content of bromide–ions in waters both at the level and lower than MAC and may be used in field conditions at the site of sampling
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The properties of heteropoly acids and of their complexes with cationic surfactants at the trace level have been studied by ESR spectroscopy, UV-VIS spectrophotometry, NMR and FTIR spectroscopy, by ...the method of chemiluminescence analysis applied in aqueous solutions and on the cellulose surface. For elucidation of the mechanism of chemiluminescence reactions of heteropoly acids with luminol kinetic methods, diffuse reflectance spectroscopy and liquid chromatography have been applied. For the first time one-electron reduction of heteropoly acids by luminol was confirmed by registration of diffuse reflectance spectra of reduced heteropoly acids on cellulose surface. It has been suggested that the mechanism of heteropoly acids immobilization on cellulose includes combination of Coulomb and hydrophobic interactions. A scheme of heteropoly acids immobilization on the surface was proposed based on ion exchange processes on cellulose or diethylaminoethyl cellulose surface. It has been shown that ionic associates heteropoly acid – cationic surfactant react with an alkaline solution of luminol with light emission similarly to heteropoly acids themselves. For the first time, heterogeneous chemiluminescence, namely, the chemiluminescence of heteropoly acids immobilized on cellulose, with luminol, has been used for examining the composition of ionic associates heteropoly acid - cationic surfactant. By using Bjerrum’s method it has been found that in strongly acidic media (at pH 1.0) vanadomolybdophosphoric acid forms with cationic surfactant, namely, with dodecylpyridinium bromide, not tetra-substituted but triply substituted ionic associate. This result can be explained by the fact that the fourth proton in H4PVMo11O40 is weakly dissociated; it is more strongly bound to heteropoly anion and is localized on the oxygen atom of the Mo–O–Mo angular bond. Ionic associates of heteropoly acids were used as analytical forms for highly sensitive chemiluminescence determination of P, As, Si, Ge in waters of different types. Detection limits for P, As, Si, Ge are 0.02–0.07 µg/L. Due to the high sensitivity of the method, phosphorus was successfully determined in surface water and ultrapure water, arsenic – in river and mineral water, silicon – in ultrapure water and vapor condensate of electric power stations, germanium – in water of electronic industry.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The monitoring of potable artesian waters of the city of Kyiv for bromide, bromate, iodide, and iodate ions as well as of drinking bottled water for bromides and bromates has been carried out. ...Bromate, iodide and iodate ions were monitored by the established methods and bromide ions—by the developed method. The stability of the chemical composition of artesian waters of the same horizon is noted. On the other hand, the concentration of bromides and iodides varied 3–4 times in pump-rooms feeding on a mixture of waters from aquifers. For waters containing high concentrations of bromides and iodides, ozonation is counter indicated due to hazard of the formation of carcinogenic bromates and iodates. A conclusion was made that it is more expedient to use carbon dioxide treatment for canning and disinfection of such waters.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The photometric method of determining trace amounts of bromates in drinking water has been developed. The method has been based on measuring diffusion reflection of tinted concentrated of the ionic ...associate of basic fuchsine with anionic surfactant; detection limit—0.5 μg/dm
3
. The analysis is not hampered by components usually interfering in determination of bromates by other methods such as chloride, chlorate, iodate, chloramines, etc. The proposed method makes it possible to control the content of bromates in water at the level and below the maximum accessible concentration.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Studies on cenopopulations of bilberry (Vaccinium myrtillus L.) were performed in 1989, 1999, and 2009 in lichen-moss pine forests exposed to emissions from the Severonickel Copper-Nickel Smelter ...Complex (Monchegorsk, the Kola Peninsula). It has been shown that, despite a five- to eightfold decrease in the amount of emissions due to production downscaling, digression processes in V. myrtillus cenopopulations are still ongoing in the impact zone. In the buffer zone, however, positive shifts in the structural organization of cenopopulations are observed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The paper examines how mechanical activation influences the in-situ phase formation of aluminosilicates in the BN-Al
2
O
3
-SiO
2
-Si
3
N
4
system. The major factor that influences the activation of ...the charge is the duration of high-energy machining. Results from infrared spectroscopy and data on the particle size and specific surface of the charge show that short-term (10–20 min) attritor grinding is sufficient to obtain a mixture and composite of high quality.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The structure and physicomechanical properties of composite materials based on boron nitride within which new phases (mullite and sialon) form during hot compaction are studied. It is established ...that the microstructure of composites is specified by their texture formation caused by the crystal morphology of boron nitride particles and it is almost independent of composite phase composition. It is shown that the main factor that affects strength is porosity. The dependence of strength on porosity is exponential in character. The strength of boron nitride-mullite and boron nitride-sialon composites is 110-140 MPa and at 20-1200 degree C it is almost unchanged.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The paper examines how mechanical activation influences the in-situ phase formation of aluminosilicates in the BN-Al sub(2)O sub(3)-SiO sub(2)-Si sub(3)N sub(4) system. The major factor that ...influences the activation of the charge is the duration of high-energy machining. Results from infrared spectroscopy and data on the particle size and specific surface of the charge show that short-term (10-20 min) attritor grinding is sufficient to obtain a mixture and composite of high quality.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
