The crystal structure of the first-synthesized compound EuErCuS3 was determined from X-ray powder diffraction data: orthorhombic crystal system, space group Pnma, structural type Eu2CuS3: ...a = 10.1005(2) Å, b = 3.91255(4)Å, c = 12.8480(2) Å; V = 507.737(14) Å3, Z = 4, and ρx = 6.266 g/cm3. The temperatures and enthalpies of reversible polymorphic transitions and incongruent melting of the compound were determined by DSC: Tα↔β = 1524 K, ΔНα↔β = 2.3 ± 0.2 kJ∙mol−1; Tβ↔γ = 1575 K, ΔНβ↔γ = 0.7 ± 0.1 kJ∙mol−1; Tγ↔δ = 1602 K; ΔНγ↔δ = 1.3 ± 0.1 kJ∙mol−1 and Tcr = 1735 ± 10 K, ΔНcr = −3.5 ± 0.3 kJ∙mol−1. IR spectra were recorded in the range from 50 to 400 cm−1. The compound was found to be IR-transparent in the range 4000–400 cm−1. The compound was characterized by Raman spectroscopy. The observed spectra featured both Raman lines and luminescence. Ab initio calculations of the EuErCuS3 crystal structure and phonon spectrum were performed, the frequencies and types of fundamental modes were determined, and the involvement of constituent ions in the IR and Raman modes was assessed from an analysis of the ab initio displacement vectors. The vibrational spectra were interpreted. EuErCuS3 manifests a ferrimagnetic transition at 4.8 K. Its microhardness is 2850 MPa. The obtained data can serve as the basis for predicting the properties of EuLnCuS3 compounds. Valence states for Eu (2+) and Er (3+) are proved both by the XRD and optical methods. Optical band gap was found to be 1.934 eV from diffuse reflectance spectrum.
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•The EuLnCuS3 compound exhibit ferrimagnetic properties at low temperature.•The polymorphic transitions for EuLnCuS3 are identified at high temperature.•EuErCuS3 is a wide-gap semiconductor.•Valence purity of Eu2+ is proved via both XRD and optical techniques•The ab initio calculation of the Raman and infrared spectra of EuErCuS3, made for Pnma symmetry, agrees well with experiment.
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•The transfer of ADBAC+ and PHMG+ across the water/NPOE boundary is suitable for cyclic voltammetry.•HILIC with NH2-column is suitable for simultaneous determination of ADBAC and ...PHMG.•CV at ITIES and HILIC are suitable for routine analysis, but need improvement.
This article describes the simultaneous determination of cationic surfactants benzalkonium chloride (ADBAC) and polyhexamethylene guanidine hydrochloride (PHMG) in stock solutions and commercial disinfectants using a novel voltammetric ion-selective electrode with a gel-like polymer composite membrane. The ADBAC and PHMG sensing methodology is based on a simple polyelectrolyte ion transfer reaction across the water/polyvinyl chloride-2-nitrophenyloctyl ether (PVC-NPOE) gel interface and was first investigated using cyclic voltammetry. Our novel electrode gave a current response proportional to ADBAC and PHMG ions ranging from 10 to 70 mg·L−1 and 25 to 120 mg·L−1, respectively, and the calculated detection limits were 1.24 mg·L−1 for ADBAC and 1.77 mg·L−1 for PHMG. As a comparative method for the determination and separation of ADBAC and PHMG, hydrophilic interaction chromatography (HILIC DAD) was used in combination with diode-array detection. LOD, LOQ, and RSD for recovery were determined for both methods, and a study of the analytical performance for both methods showed that the electrochemical method was more sensitive but had a larger error and a narrower range of linearity. The applicability of both methods to the routine analysis of disinfectants is discussed.
A description of a COVID-19 patient with the development of exudative pericarditis complicated by cardiac tamponade is provid. A peculiarity of this case is the presence of an underlying disease in ...the patient (chronic lymphocytic leukemia), which was in remission for 1.5 years after chemotherapy. Another feature of the patient was the relatively small area of lung damage and the hemorrhagic nature of the pericardial effusion, which persisted for a long time. The insignificant activity of inflammatory markers was noteworthy. Possible mechanisms of development and features of the course of exudative pericarditis in the described patient, issues of diagnosis and treatment of this category of patients are discusse.
A kind of autoimmune encephalitis with positive autoantibodies toward the B1 subunit of the gamma-aminobutyric acid-type B receptor is known as anti-GABABR encephalitis. It is an autoimmune brain ...disorder with typical manifestations of a limbic encephalitis. It can coexist with positive anti-thyroid autoantibodies. We described a 57-year-old woman who was diagnosed with a bipolar affective disorder. The patient had high titers of anti-thyroid peroxidase antibodies, and she also was positive for anti-GABABR antibodies. There is a question, if this case is a kind of comorbidity of anti-thyroid and anti-brain autoimmunity or is it a single nosological entity – a kind of Hashimoto’s encephalopathy?
For the first time, silicate‐substituted hydroxyapatites have been prepared from mixtures containing different amounts of silicon (0.2–2 mol per mol of apatite unit cell) by dry mechanochemical ...synthesis at room temperature in a planetary ball mill. The XRD, FTIR, TEM, and NMR spectroscopic data show that the product of the mechanochemical synthesis is a single‐phase nanocrystalline apatite containing different amounts of carbonate and silicate ions and adsorbed water. In the annealed samples, three silicon concentration subranges can be distinguished, each of which is characterized by specific evolution of the lattice parameters. The formation mechanism of the silicate‐substituted hydroxyapatite obtainable by this method is discussed. The studies indicate that the silicon substitution limit in the silicate‐substituted lattice achievable by the dry mechanochemical synthesis followed by heat treatment is 1.2 mol per mol of apatite unit cell.
Silicate‐substituted hydroxyapatite powders containing different amounts of silicon have been synthesized by the mechanochemical method. Several apatite crystal structures that differ by the position of the hydroxy groups have been identified.
In memory of David Abramovich Kirzhnits Andreev, Aleksandr F; Bolotovskiĭ, Boris M; Ginzburg, Vitalii L ...
Physics Uspekhi,
01/1999, Letnik:
42, Številka:
1
Journal Article
The crystal structures of the complex sulfides SrLnCuS3 (Ln = Sm, Gd, Er and Lu) have been determined and refined using powder X‐ray diffraction. The crystals are found to be orthorhombic, with the ...structure type changing consecutively in the order BaLaCuS3 → Eu2CuS3 → KZrCuS3 as the Ln3+ ionic radius decreases in the order La/Pr → Sm/Gd → Er/Lu. Variations of the structure parameters along the series of compounds studied are analyzed, and an effect caused by crystallochemical contraction on the stabilization of the respective structure types is demonstrated.
In the crystal structures of the complex sulfides SrLnCuS3, as the ionic radius (Ln3+) decreases, the structure type changes consecutively in the order BaLaCuS3 (La, Pr) → Eu2CuS3 (Sm, Gd) → KZrCuS3 (Er, Lu).
A process of plasma electrodes and optical transmission "window" formation in electrooptical switch (Pockels cell) of high-power laser radiation pulses is studied experimentally and analyzed ...numerically. A 2-D computer model of a gas discharge, forming the electrodes and allowing for the charged particles transport and reactions kinetics in self-consistent electric field is developed. A time dependence of the optical transmission in various points of the cross section of the cell operating in the two-pulse mode is computed. In the cell center, the calculated dependence is consistent with the optical transmission oscilloscope trace.
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