An analysis of geochemical features of crystallization of emeralds as an approach to determine the deposit of them

Relevance. It is known that minerals differ in morphology, features of the internal structure of crystals, chemical composition, etc., depending on the conditions of their formation and existence. These geochemical features of the gems crystallization are an important criterion for determining their deposit. In this paper, the impurity composition of the samples of emeralds from the deposits of Brazil, China, Zambia, Russia, Afghanistan, Colombia, and Tanzania was investigated by X-ray fluorescent analysis. The study of the impurity composition of emeralds by a non-destructive method and the construction of analytical dependences can be used as an additional way for determining the deposit of emeralds. Purpose of the work is the study of chemical composition of emeralds by X-ray fluorescent analysis to establish the relationship between the content of the main impurity elements and the deposit. Results. The data on the impurity composition of emeralds obtained by X-ray fluorescent analysis show that the content of impurities of Na, K, Rb, Cs, Mg, Fe, V, Cr differs from one deposit to another. The content of impurities of alkali metals and magnesium is higher in the samples from the shale-type deposits compared to the samples from deposits of the Colombian type. Thus, at the first stage, the type of deposit can be assumed. Further, the dependences plotted in the coordinate planes {Cr, V}, {Cs, Cr}, {Fe, Cr} show separate areas, delimited by the impurity ratios, which are typical for the samples from deposits in China, Colombia, Zambia, Afghanistan, and Tanzania. Conclusion. X-ray fluorescent analysis, as a non-destructive method for studying emeralds, is considered to be a promising approach to identifying their deposit, but as an additional method.

ДОСЛІДЖЕННЯ ВАЛІДАЦІЙНИХ ХАРАКТЕРИСТИК МЕТОДИКИ КІЛЬКІСНОГО ВИЗНАЧЕННЯ ПАРАЦЕТАМОЛУ ТА ЙОГО ОСНОВНОЇ ДОМІШКИ В РЕКТАЛЬНИХ СУПОЗИТОРІЯХ

Еxploration of validation characteristicsof the method for the quantitative determination of paracetamol and its main impurity 4-aminophenol in rectal suppositories by spectrophotometry (UV) and high performance liquid chromatography (HPLC). Spectrophotometric measurements were carried out on a UV VIS Lambda 35 spectrophotometer (Perkin Elmer, USA) in cuvettes l = 1 cm. We used a Waters 2695 liquid chromatography with a Waters 2489 UV-detector, as well as a Nucleosil C18 chromatographic column with a size of 250 × 4.6 mm, filled with octadecylsilyl sorbent with a particle size of 10 microns. We used reagents: purified water, which was obtained from the Milli Q plant, manufactured by Millipore Corporation (Germany), sodium hydroxide Sigma-Aldrich, cat. № 06203, sodium 1-butanesulfonate Sigma-Aldrich, cat. № 19022-10G-F; ethanol 96%, methanol Sigma-Aldrich (purity 99.9%), formic acid Sigma-Aldrich, cat. № 33015. Validation characteristics were confirmed as specificity, correctness, precision. The total predicted uncertainty of the analytical method for quantitative determination and the limit of quantitative determination of the main impurity of paracetamol, at which the signal-to-noise ratio is fulfilled, is 10% of the initial concentration of the reference solution (0.5 μg / ml). Confirmed linearity for quantitative determination of paracetamol content in the range of 80 to 120% of the nominal value. Statistical processing of experimental data was carried out; the correlation coefficient of the linear dependence (r) between the entered and found values for the quantitative determination of paracetamol is > 0.990, which indicates the correctness of the method. Methods for the quantitative determination of paracetamol and its main impurity in suppositories have been developed and validated. The method for quantitative determination of paracetamol in suppositories is significantly simpler for routine control of a batch of drugs and is cost-effective compared to the HPLC method. The obtained experimental results indicate that according to the studied validation characteristics, the technique is correct and can be reproduced in other laboratories.

A green method for the preparation of phoxim based on high-boiling nitrite

Phoxim is a significant insecticide, and its current synthesis method has some shortcomings such as the high risk of explosion and the trans structure (main impurity) is hard to control. Our work solved the above disadvantages by introducing macromolecular alcohol (benzyl alcohol, etc.) as the starting material and optimizing the intermediate reaction conditions. Compared with the current synthesis route, the synthetic method has the following advantages: (1) intermediate benzyl nitrite has a high boiling point and strong safety; (2) intermediate α-cyanobenzaldehyde oxime sodium are almost (≥99%) cis structure, and no further refinement was required, which greatly reduced the amount of waste water produced; and (3) The high yield of phoxim was maintained at 72.9%.

Cross sections and production yields of 117mSn and other radionuclides generated in natural and enriched antimony with protons up to 145 MeV

Cross sections of a prospective medical radionuclide 117mSn along with 113Sn, 120m,122Sb, 111,114mIn and 118,119m,119g,121m,121g,123mTe generated in natural and enriched antimony targets by protons in a wide energy range up to 145 MeV were determined. A stacked-foil technique followed by gas chemical separation and γ-ray spectrometry were used. The obtained data were compared with experimental values reported in literature and with theoretical computations by ALICE, TALYS and Cascade-Evaporation-Fission codes. Production yields of 117mSn and the main impurity 113Sn were estimated for different irradiation modes.

Gold and other impurity elements in pyrite from the Berezovskoe deposit in the Middle Urals

Research subject. In this work, we investigated the crystals of pyrite, one of the key gold-bearing minerals, from the Berezovskoe (the Middle Urals) deposit using modern research approaches.Materials and methods. Samples for the analysis were collected from the ladder sulphide-quartz veins and related berezites in the Ilinskaya, Pervopavlovsk and Vtoropavlovsk dykes of the Berezovskoe deposit. The ores were studied using the methods of optical microscopy, X-ray microanalysis (PCMA), scanning electron microscopy (SEM) and LA-ICP-MS. The latter method was largely used to examine pyrite. Along with pyrite, the materials under study included faded ore, galena, and such rare occurring minerals as aikinite, cosalite, tetradymite and tsumoite. Results. According to the point and profile analysis, as well as grain mapping, the main impurity elements in the stu died samples are found to be Co, Ni and As. The distribution of these elements has shown a zonal character: the amounts of Co and Ni tend to increase and that of As tends to decrease towards the grain centre. In the pyrite samples, Cu, Zn and Pb occur either in the form of their sulphide micro-inclusions or as evenly distributed admixtures. The pyritic ore of later genera tions in the Pervopavlovsk dyke is established to contain gold in amounts of up to 22 g/t, with Au being zonally distributed. The goldbearing variety of pyrite is characterized by abnormally low contents of Co and Ni, as well as by an increased content of As (up to 8000 g/t). Conclusion. A common character of the distribution of main impurity elements in the pyritic ores in the studied dikes indicates similar conditions of their crystallization. The presence of late-generation pyrite with fine gold in the Pervopavlovsk dike evidences to a heterogeneous distribution of gold mineralization therein, likely due to the multistage character of the latter. This may also be an indicator of the concentration of ore columns, which fact requires further elucidation.

Synthesis of h-BN by the Combustion of B/KNO3/Octogen Mixture under Nitrogen Atmosphere

Hexagonal boron nitride (h-BN) powders were fabricated by the combustion synthesis with B/KNO3/HMX (octogen) mixtures as reactants. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were adopted to investigate the phase composition and the chemical composition of the products, respectively. The morphology and resistance to oxidation were studied by scanning electron microscopy (SEM) and thermogravimetry (TGA), respectively. The characterization results showed that the h-BN which was produced through this method has high purity and exhibits excellent resistance to oxidation. The purity of h-BN is improved with the increasing content of HMX in reactants with boron carbide (B4C) and boron oxide (B2O3) as main impurity, but conversely, the yields are obviously decreased. Taking the comprehensive consideration of the purity and the yields together, the optimal molar ratio of B/KNO3/HMX is 10 : 1 : 4. In addition, the experimental results indicated that the crystalline grain size grows with the increasing content of HMX. The method explored in this study does not need expensive processing facilities and equipment, which is a preferable approach for the laboratory to prepare h-BN of high purity.

Study of the physicochemical properties of exosome dispersions obtained by ultrafiltration

The article presents the results of studying the physicochemical properties of exosome preparations obtained by ultrafiltration, which indicate a high degree of the composition and properties dependence of the obtained product on the material of the filters used. Quantitative determination of proteins and nucleic acids in exosome samples using UPN-50 filters allows us to conclude that the content of the main impurity compounds in the preparation is significantly reduced compared to dispersions obtained using filters with pore sizes of 220 and 450 nm. Analysis of flow cytometry data made it possible to demonstrate that when using the UPN-50 filter, an increase in the contribution to the dispersion of all types of fractions of non-exosomal size was observed, the appearance of which can result from fraction destruction associated with pore size or filter material properties. drying of the dispersion was observed in the studied exosome samples. Fraction sizes ranged from 40 to 450 nm (an average of about 200 nm). Exosomes from the entire variety of membrane vesicles are fractions that have the most suitable characteristics that allow them to be used as a nanoscale drug delivery vehicle while ensuring the necessary quality control of the drug at the sample preparation stage.

Electrorefining of High Carbon Ferromanganese in Molten Salts to Produce Pure Ferromanganese

High carbon ferromanganese is used as a starting material to prepare pure ferromanganese by electrorefining in molten salts. High carbon ferromanganese was applied as the anode, molybdenum was the cathode and Ag/AgCl was the reference electrode. The anodic dissolution was investigated by linear polarization in molten NaCl-KCl system. Then potentiostatic electrolysis was carried out to produce pure ferromanganese from high carbon ferromanganese. The cathodic product was determined to be a mixture of manganese and iron by x-ray diffraction (XRD). The content of carbon in the product was analyzed by carbon and sulfur analyzer. The post-electrolysis anode was characterized by scanning electron microscope (SEM). The mechanism of the anode dissolution and the distribution of the main impurity of carbon and silicon after electrolysis were discussed.

Investigation on the Reduction of Ilmenite at Lower Temperatures

The solid state reduction of ilmenite was studied using thermogravimetric analysis by a combination of XRD, SEM& EDS methods. Results showed that MgTiO3 was the main impurity and influenced the reduction process of ilmenite. When the temperature was below 1000°C, reduction was controlled by the chemical reaction and the activation energy was 163 kJ/mol. Pretreatment of milling accelerated the solid reduction rate.