Search

The problem of using octanometers for the rapid control of the octane number of compounds in the production of commercial gasoline is considered, and the factors forming it are indicated. Error spectra of a multidimensional absorption spectral analytic signal of commercial gasolines and compounds of their individual fractions (components) were studied in measurements in the mid-IR region. The effect of a change of the proportion of the main constituents (aromatic hydrocarbons, benzene catalysate, isomerizate, methyl tert-butyl ether, and isopentane) in the compound on the spectra of commercial gasolines was evaluated. Multidimensional measurements of light absorption by gasolines in a wide spectral region and difference spectra were used. It was shown that spectral noise does not form limitations in spectroscopic measurements, while uncontrollable variations in the process conditions can form significant deviations in the absorption spectra, leading to problems in using calibration characteristics based on commercial gasoline samples. [ABSTRACT FROM AUTHOR]

To assess a possibility of the measurement of the relative concentration of main gasoline components under varied conditions, we studied the absorption of electromagnetic radiation by these components in the mid-IR region. The results for the absorbance of gasoline with varying concentrations of components, obtained using Fourier-transform IR spectroscopy are presented. The use of multidimensional difference spectra of gasoline is the most effective and informative way to perform measurements. The high sensitivity of the difference spectra to changes in the composition and concentrations of the main gasoline components is demonstrated. [ABSTRACT FROM AUTHOR]

Spurrite from Negra Mine, Queretaro, Mexico is characterized by a complex chemical composition. Its empirical formula derived based on electron microprobe, wet chemical analyses and gas chromatography of annealing products is H0.18Ca5.01Na0.05[(SiO4)1.91(SO4)0.08)][(CO3)0.71(BO3)0.28]O11. The mineral was studied by single-crystal X-ray diffraction (SCXRD) as well as infrared (IR), Raman and nuclear magnetic resonance (NMR) spectroscopy. According to spectroscopic data, boron has three-fold coordination and sulfur occurs in the mineral in the sulfate form. A significant portion of carbonate groups is substituted by BO33– anions. Charge compensation is achieved due to the substitution of a part of SiO44– anions by SO42– groups, as well as to the admixture of sodium. SCXRD shows that sodium occurs in its own site with a low occupancy. The studied sample is isotypic with the synthetic NaCa5(SiO4)2(BO3) compound. The IR spectrum shows possible partial protonation of the SiO4 tetrahedra whereas bands of H2O molecules and isolated OH– anions are not observed. Thermal behavior of B,S,Na-bearing spurrite from Negra Mine has been studied using powder high-temperature X-ray diffraction (HTXRD) together with boron poor and S-free spurrite from Fuka Area (Japan). The studied samples are stable up to ~ 1200 °C and ~ 1100 °C, respectively, whereas synthetic B,S-free spurrite decomposes at about 900 °C. The thermal expansion is significantly anisotropic and is observed mainly in the direction perpendicular to the ac plane which is coplanar with the layers of calcium polyhedra and anionic pseudo-layers formed by (C,B)O3 triangles and (Si,S)O4 tetrahedra. Isomorphism and a similarity of the thermal, baric and compositional (C-B substitution) deformations of spurrite-like structures are discussed. [ABSTRACT FROM AUTHOR]

Sergeysmirnovite, MgZn2(PO4)2 · 4H2O, is a new mineral from the oxidation zone of the Kester mineral deposit, Sakha-Yakutia, Russia. This mineral forms tabular colorless crystals growing on quartz and fluorapatite aggregates in association with pseudomalachite, libethenite, native copper, a Na-analogue of batagayite, arsenolite, tobermorite, epifanovite, and batagayite. The mineral is orthorhombic, with the space group Pnma. The unit cell parameters refined from powder X-ray diffraction data are the following: a = 10.5957(6) Å, b = 18.365(1) Å, c = 5.0320(4) Å, V = 979.16 (8) Å3. The eight most intense powder X-ray diffraction lines are the following (I-d[Å]-hkl): 100-5.28-200; 33-4.576-040; 24-3.999-230; 24-3.877-031; 22-3.387-221; 44-3.015-250; 57-2.854-311; 34-2.647-400. Sergeysmirnovite belongs to the hopeite group and is dimorphous with reaphookhillite. The mineral is named in honor of famous Soviet geologist, Academician Sergei Sergeevich Smirnov (1895–1947), a renowned specialist in the mineralogy of ore deposits. [ABSTRACT FROM AUTHOR]

The possibility of the application of high-uranium self-irradiation-damaged metamict zircon for U-Pb geochronological studies (ID-TIMS) after preliminary high-temperature annealing and acid treatment was demonstrated using zircon from the Li–F granites of the Turga massif (Eastern Transbaikalia). Optimal conditions of high-temperature annealing and acid treatment of zircon with high self-irradiation α-dose can be selected to remove completely a metamict phase and preserve sufficient quantities of the mineral for U-Pb (ID-TIMS) studies. [ABSTRACT FROM AUTHOR]

Microporous silicate tiettaite from the Khibiny alkaline massif (Kola Peninsula, Russia) has been studied using X-ray diffraction analysis, electron probe microanalysis, and Raman spectroscopy of single crystals and powders. Its chemical formula is refined to be K4Na12Fe3+Si16O41(OH)4⋅ 2H2O. The Raman spectrum of tiettaite contains lines at 3650, 3450, 1097, 1066, 980, 920, 681, 635, 569, 499, 458, 404, 272, 144 cm–1. The orthorhombic unit-cell parameters are a = 28.866(7) Å, b = 10.707(3) Å, c = 17.425(7) Å, V = 5385(3) Å3, Z = 4, sp. gr. Cmcm. The tiettaite crystal structure has been solved for the first time from single crystal and refined by the Rietveld method to the final Rwp = 2.47% and RBragg = 1.38%. The structure based on a new-type microporous heteropolyhedral framework formed by one-dimensional modules [Si28Na16Fe4K4O110]76– elongated along the c axis. Each module consists of complex ribbons with compositions of [Si14O39]22– and [Fe2K2Na6O32]50– compose a framework via shared vertices of half-occupied silicon–oxygen tetrahedra Si5 and Si6. Tiettaite structure contains a three-dimensional system of crossed channels with effective channel widths of 2.61 × 7.50, 2.46 × 2.92, and 3.60 × 3.90 Å2, running along the [100], [010], and [001] directions, respectively. The presence of a system of broad channels allows one to consider tiettaite as promising ion exchanger. Regarding the information complexity parameters, tiettaite can be assigned to minerals with very complex structure. [ABSTRACT FROM AUTHOR]