Over the last decades, optical spectroscopy methods that do not require complex sample preparation have been widely used to identify and control the composition of food products. In the present study, the possibility of using UV-VIS-NIR spectroscopy combined with multivariate analysis for grading wheat flour into groups differing in technological properties was analyzed. UV-VIS-NIR spectra contain information on the combination and intensity of absorption bands assigned to functional groups of the composition components and determining the technological properties of wheat flour. The database of UV-VIS-NIR spectra of wheat flour samples differing by technological properties was formed into three groups: the first group — wheat flour samples with good baking properties, the second group — with reduced baking properties, the third group — with low baking properties. The visible range of UV-VIS-NIR diffuse reflectance spectrum was used to calculate the color coordinates in the CIE colorimetric system L*a*b*. The greatest difference among the groups in the color coordinates of the samples was found for the coordinate b*, which is associated with the different content of coloring pigments. The spectra database was used to build a classification model for grading wheat flour into quality groups using a combination of principal component analysis and linear discriminant analysis (PCA-LDA) methods. The achieved results indicate that the classification model built on the training sample is able to distinguish wheat flour spectra by quality groups with an accuracy of 96.49%. The effective- ness of the model is verified using a test set of spectra of wheat flour samples. The present study confirms that the combina- tion of UV-VIS-NIR spectroscopy in conjunction with the PCA-LDA method has significant potential for determining a quality group of wheat flour based on technological properties.

The phase formation of neodymium tungstate Nd2WO6 from mechanically activated oxides was studied in a wide temperature range: 25–1600°C. Conditions for the formation of various polymorphic modifications were determined: low-temperature orthorhombic β-Nd2WO6 and δ-Nd2WO6 (P212121 (no. 19)); high-temperature monoclinic Nd2WO6 (C12/c1 (no. 15)). Optical absorption spectra were studied for polymorphic ceramics with a nominal composition of Nd2WO6. Differences in the spectra of δ-Nd2WO6 and monoclinic Nd2WO6 were detected. Both modifications (δ-Nd2WO6 and monoclinic Nd2WO6) showed proton conductivity with activation energies of 1.05 and 1.06 eV, respectively. For the Ca-containing solid solution with a monoclinic structure (Nd _1 - x Cax)2WO _6-δ (x = 0.01), whose overall conductivity increases compared to that of pure monoclinic Nd2WO6, hole conductivity predominates in air.

The results of identity composition of coloured technicl gypsum as a waste product of vanadium production at OAO "EVRAZ Vanadiy Tula" were presented. It was shown that gypsum is converted into anhydrite during heat treatment at 700 °C. It was proved that waste coloring is due to the presence of manganese hydroxide and vanadium oxide, their interaction during heat treatment forms manganese vanadate Mn 2 V 2 O 7 and changes the color tone of the product. As decorative building materials, it is recommended to use colored gypsum-containing waste and products of their heat treatment.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X22330017

Background. The Stolbovoe deposit is located in the northern part of the Eastern Sayan, in the Nizhneudinsky district of the Irkutsk region, within the N-47-IX map sheet. The surveying of the territory began in the sixties of the last century. The Stolbovoe deposit was discovered based on direct search signs (radioactivity). At the same time, the search was not aimed at revealing new deposits hidden under the Riphean cover; therefore, most of the territory remained unexplored.Aim. To map and classify the near-ore hydrothermal-metasomatic alterations manifested on the flanks of the Stolbovoe uranium deposit.Materials and methods. During the 2018–2020 period, within the framework of prospecting work, the employees of the All-Russian Scientific-Research Institute of Mineral Resources named after N.M. Fedorovsky (VIMS) carried out the mapping of ore alterations using an innovative method of Infrared (IR) spectroscopy. The diagnostics of mineralization was carried out using a portable TerraSpec 4 Hi-Res spectrometer. The instrument was used to measure diffuse reflectance spectra in the Ultraviolet-Visible-Short-Wave Infrared (UV-Vis-SWIR) ranges; the composition of various mineral phases was determined using the TSGVersion 7 database and software.Results. This study confirmed the efficiency of the method applied for the diagnostics of all varieties of clayey (kaolinite, montmorillonite) and fine micaceous (phengite, sericite, paragonite and their illite varieties) minerals, as well as carbonates (dolomite, ankerite, siderite) and chlorites in the rock in situ or in samples without preliminary sample preparation.Conclusions. The use of the described method for investigating cores and samples of the Stolbovoe uranium deposit (East Sayan region) made it possible to classify the epigenetic changes in rocks and to map hydrothermal-metasomatic halos, including those near-ore, formed by mineralization that could not be identified by conventional visual and optical methods.

Rare minerals represented by oxides, fluorides, F-carbonates and REE arsenates in association with monazite-Ce, monazite-Th, xenotime-Y and zonal REE fluorite were identified in the rare-metal ores of the Sn–W deposits of Lesser Khingan, Amur region. Rare lanthanide minerals are described, including fluocerite, bastnaesite, and gasparite-Ce, which was found for the first time in Russia in the Sn–W greisens, and chernovite-Y, the second find in the greisens of the Russian Far East. The influence of arsenic fluids at the late hydrothermal stage caused the replacement of xenotime-Y and monazite-Ce by diverse REE minerals with different lanthanide proportions. It is found that these minerals differ in chemical composition from the same minerals described in other deposits elsewhere. Due to the variable valence state of arsenic and the complete isomorphism between rare earths, arsenates can be used as indicators of redox conditions of their deposition.

In the Sn–W greisen deposits of the Karadub ore field, rare arsenates of REEs chernovite-(Y) and gasparite-(Ce), associated with topaz, fluorite, fluocerite, and bastnaesite, have been identified. They replace early xenotime-(Y) and monazite-(Ce). Chernovite-(Y) and gasparite-(Ce) from Sn–W greisens differ in their chemical composition from the same minerals previously described elsewhere. Chernovite-(Y) differs in the minimum content of Y with only 0.47 to 0.26 atoms in the formula (a.p.f.) and a relatively high content of light REEs of 0.111–0.254 (a.p.f.). Gasparite-(Ce) has a high Nd content of 0.28 (a.p.f.). REE arsenates were formed by substituting xenotime (Y), monazite (Ce), and REE-bearing fluorite under strongly oxidizing conditions.

The results of the procedure of the volumetric-spatial mapping of firing conditions by the UV–VIS–NIR spectrum of ceramic bricks from one batch by the multivariate analysis methods are presented. The principal component method identified the absorption bands of the spectrum, which are attributed to the color centers of iron-containing impurities. The discriminant ability of color coordinates a* > b* > L* is determined when grading products into groups of samples with similar color characteristics. The volumetric-spatial mapping of firing conditions by UV–VIS–NIR spectra of ceramic products makes it possible to select samples for testing at control points according to the volume of a batch of products.

New nonstoichiometric SmAl-dimetaborate crystals were synthesized using spontaneous nucleation from Sm2O3 - B2O3 - K2Mo3O10 flux melt. The room temperature and low-temperature single-crystal XRD investigations were carried out. Obtained solids crystallize in the non-centrosymmetric space group P (6) over bar2 m, with unit cells parameters a = b = 4.570(1) angstrom, c = 18.521(1) angstrom, V = 335.00(1) angstrom(3) (for Sm2Al3.84B8O21.27, T = 295 degrees K) and a = b = 4.563 (1) angstrom, c = 18.505(1) angstrom, V=333.91(1) angstrom(3) (for Sm2Al3.96B8O21.30, T = 90 degrees K), and z = 1. A comprehensive study of samarium double-cell polytype crystals was performed using scanning electron microscopy, luminescence spectroscopy and Raman measurements.

The results of a study of the use of non-destructive contact-free optical spectroscopy — registration of UV-VIS-NIR-range diffuse reflection spectra and photoluminescence spectra — for the identification of porcelain products are reported. Based on the color characteristics and a list of optically active centers of luminescence (OALC) porcelain products were graded according to the composition and state of the redox medium during firing. It is shown that the chromaticity of porcelain can be controlled by means of a combination of color and luminescence centers and their intensity ratio. A decrease in the intensity of the OALC Fe3+ band is mainly related to a change in the coordination of iron Fe3+O4 → Fe3+O6 in bone china.

The application of UV-VIS-NIR spectroscopy combined with multivariate analysis for the classification and identification of buckwheat groats was analyzed. Samples of buckwheat groats differing in harvest time, kernel size, roasting method, and storage time were divided into groups using a cluster analysis method. The principal components method revealed absorption bands in UV-VIS-NIR spectra corresponding to functional groups of the composition components and contributing most to differentiation of the samples into buckwheat quality categories. Discriminant analysis confirmed a hypothesis on dividing the buckwheat samples into groups and formulating a classification function to identify and sort buckwheat groats.

It is introduced to use a portable spectrometer along with a calibration model for rapid quality control of metakaolin in situ. Verification of the calibration model for predicting the values of two indicators: total acid solubility and mass loss during calcination, indirectly characterizing the pozzolanic activity of metakaolin.

Diffuse reflection UV-VIS-NIR spectroscopy was used to study changes in the color of facing bricks from the content of the additive of manganese tetraoxide (Mn3O4) into the ceramic mass. This investigation was shown that with an increase of the additive content, both the intensity of the absorption bands of colored bricks corresponding to hematite decreases, and the absorption intensity increases with a shift in the maximum of the wide absorption band from the visible to the near-infrared range of the spectrum. By changing the values of the color coordinates in the CIE L*a*b* and Mansell systems: lightness and color, and the values of the indicator-relative color ability, it is fixed that the color of a brick depends on the ratio of two pigments: yellowish-red of hematite and black, probably jacobsite in its composition.

The colloform tin ores from the deposit Verkhnee at the Primorye have been studied with the aid of X- ray spectroscopic microanalysis and the scanning electron microscopy with the energy dispersive analyzer LINK-ISIS that allowed revealing the primary and the secondary zoning of a colloform cassiterite and to determine the phase composition of these formations. The primary zoning of the mineral forms at the early stage of the deposition of stannates from colloidal solutions and is characterized by the alternation of hydrostannates of various composition. The secondary zoning is superimposed zonality, and it forms at the process of the stannate crystallization. The metacolloidal varieties of concentric-zonal aggregates are produced by hydrostannates of Ca, Fe, Cu, In, of variable compositions, soluble in acids, in which the admixtures of As, Al, Si, Cd, Co, Sb, Zn, Ag are marked. Sn content according to the energy dispersive analysis is 42—54%. Infrared adsorption spectroscopy allowed finding out in hydrostannates the presence of the hydroxyl water at the area of the valence vibrations Sn-OH. In the colloform cassiterite a new phase Pb5 As2 O8 with various correlation of Pb and As in size 30—50 mk has been found.

Nipalarsite, Ni8Pd3As4, is a new platinum-group mineral discovered in the sulfide-bearing orthopyroxenite of the Monchetundra layered intrusion, Kola Peninsula, Russia (67 degrees 52'22 '' N, 32 degrees 47'60 '' E). Nipalarsite forms anhedral grains (5-80 mu m in size) in intergrowths with sperrylite, kotulskite, hollingworthite, isomertieite, menshikovite, palarstanide, nielsenite and monchetundtraite enclosed in pentlandite, anthophyllite, actinolite and chlorite. Nipalarsite is brittle, has a metallic lustre and a grey streak. In plane-polarised light, nipalarsite is light grey with a blue tinge. Reflectance values in air (in %) are: 46.06 at 470 nm, 48.74 at 546 nm, 50.64 at 589 nm and 54.12 at 650 nm. Values of VHN20 fall between 400.5 and 449.2 kg.mm(-2), with a mean value of 429.9 kg.mm(-2), corresponding to a Mohs hardness of similar to 4. The average result of 27 electron microprobe wavelength dispersive spectroscopy analyses of nipalarsite is (wt.%): Ni 44.011, Pd 28.74, Fe0.32, Cu 0.85, Pt 0.01, Au 0.05, As 25.42, Sb 0.05, Te 0.39, total 99.85. The empirical formula (normalised to 15 atoms per formula unit) is: (Ni8.10Fe0.06)(Sigma 8.16)(Pd2.94Cu0.18)(Sigma 3.12)(As3.68Te0.03)(Sigma 3.71) or, ideally, Ni8Pd3As4. Nipalarsite is cubic, space group Fm (3) over barm, with a = 11.4428(9) angstrom, V= 1498.3(4) angstrom(3) and Z= 8. The strongest lines in the powder X-ray diffraction pattern of synthetic Ni8Pd3As4 [d, angstrom (I) (hkl)1 are: 2.859(10)(004), 2.623(6)(313), 2.557(6)(024), 2.334(11)(224), 2.201(35)(115,333), 2.021(100)(044), 1.906(8)(006,244) and L429(7)(008). The crystal structure was solved and refined from the single-crystal X-ray diffraction data of synthetic Ni8Pd3As4. The relation between natural and synthetic nipalarsite is illustrated by an electron back-scattered diffraction study of natural nipalarsite. The density calculated on the basis of the empirical formula of nipalarsite is 9.60 g.cm(-3). The mineral name corresponds to the three main elements: Ni, Pd and As.

The colloform tin ores from the deposit Verkhnee at the Primorye have been studied with the aid of X- ray spectroscopic microanalysis and the scanning electron microscopy with the energy dispersive analyzer LINK-ISIS that allowed revealing the primary and the secondary zoning of a colloform cassiterite and to determine the phase composition of these formations. The primary zoning of the mineral forms at the early stage of the deposition of stannates from colloidal solutions and is characterized by the alternation of hydrostannates of various composition. The secondary zoning is superimposed zonality, and it forms at the process of the stannate crystallization. The metacolloidal varieties of concentric-zonal aggregates are produced by hydrostannates of Ca, Fe, Cu, In, of variable compositions, soluble in acids, in which the admixtures of As, Al, Si, Cd, Co, Sb, Zn, Ag are marked. Sn content according to the energy dispersive analysis is 42—54%. Infrared adsorption spectroscopy allowed finding out in hydrostannates the presence of the hydroxyl water at the area of the valence vibrations Sn-OH. In the colloform cassiterite a new phase Pb 5 As 2 O 8 with various correlation of Pb and As in size 30—50 mk has been found.

Ванадиевый травяно-зеленый дравит обнаружен в маломощных (до 10 см) кварцевых жилах, пересекающих черные кремнистые сланцы позднего протерозоя, обогащенные ураном и ванадием (до 50 ppm). Содержание V2O3 в – до 5.34% при низком содержании железа и повышенном магния. По всей вероятности, ванадий занимает в структуре минерала в основном Z-позицию. Получены спектры диффузного отражения в диапазоне 350–2500 нм и люминесценции при возбуждении УФ-излучением N-лазера. Появление ванадия в качестве хромофора и люминофора в метаморфических породах интерпретируется как индикатор древних океанических структур на континентах. В статье 11 рисунков, 2 таблицы, 21 литературная ссылка.