High-pressure Raman study of nyerereite from Oldoinyo Lengai

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Crystal structures of K-cymrite and kokchetavite from single-crystal X-ray diffraction

Recent research on superconductivity of high-pressure hydrides generated many phase stability calculations with a lack of their experimental verification; a typical example is Pt–H system. The stability of eight PtH structures was predicted, while the experiments revealed the existence of only hexagonal close-packed (hcp) and trigonal PtH. Face-centered cubic (fcc) PtH was predicted to be nearly isoentalpic to the hcp PtH and stable near 100 GPa, but never observed experimentally. Here we report the first synthesis of the fcc PtH using laser-heated diamond anvil cell. It was found to occupy a high-temperature area of the phase diagram in a wide pressure range of 20–100 GPa, being metastable at room temperature. Our results look promising for uncovering weak approximations in current high-pressure hydrides stability ab initio calculations

Raman spectra of shortite Na₂Ca₂(CO₃)₃ compressed up to 8 GPa

<p>A rare mineral shortite, Na₂Ca₂(CO₃)₃, occurs among groundmass minerals in unaltered kimberlites, which suggests its participation in the evolution of kimberlite system. This work presents a high pressure Raman spectroscopic study of natural shortite (Udachnaya east kimberlites) compressed in KBr up to 8 GPa in a diamond anvil cell. At ambient pressure the spectrum contains two strong bands related to symmetric C-O stretching vibrations, four in-plane bending modes, and several low-frequency modes of lattice vibrations. Upon the pressure increase up to 8 GPa, almost all the bands exhibit positive shift with the rate of 1–4 cm⁻¹/GPa for the lattice modes and 3.6 and 3.9 cm⁻¹/GPa for the C-O stretching modes. The shifts of Raman modes are rather regular, which implies the absence of reconstructive phase transitions within the studied pressure range, similarly to the behavior of nyerereite, a related carbonate mineral. However, minor anomalies in the ν/<i>P</i> and FWHM/<i>P</i> dependences, observed at about 2 GPa, suggest some rearrangement and disordering of carbonate groups. The obtained data can be used for the estimation of residual pressure in shortite-bearing inclusions in deep-seated minerals.</p

Distribution, excretion and metabolic pathways of a single parenteral administration of kappa-opioid receptor agonist RU-1205

Introduction: The purpose was to study the pharmacokinetic properties of RU-1205 with the previously identified kappa-agonistic and analgesic effects after parenteral administration. Materials and methods: Pharmacokinetic parameters of RU-1205 after intravenous and subcutaneous administration at doses of 10 mg/kg and 50 mg/kg, respectively, were investigated, using the method of high-performance liquid chromatography with measurement of the compound according to a pre-established calibration curve. The indices of the area under the pharmacokinetic curve, clearance, half-life, residence time of the drug molecule in the body, total (apparent) volume of distribution, as well as the indicator of absolute bioavailability for subcutaneous administration were calculated. Tissue distribution and excretion of RU-1205 were also studied. Evaluation of metabolism of RU-1205 was conducted in silico, using the PALLAS 3.00 software, with the use of specific tests with CYP 450 substrates and by studying the ability of RU-1205 to form conjugates with endogenous acids. Results and discussion: It was found that after a single intravenous administration, the investigated substance was determined in the blood for 12 h; the half-life was 8.49 hours. The absolute bioavailability after subcutaneous administration is 57.35%. RU-1205 is eliminated within 3–4 days. The main route of excretion is extrarenal. The biotransformation of the substance probably proceeds mainly with the formation of oxidized forms of the initial molecule according to the reactions of the first phase of metabolic transformation, so the chance to observe phase 2 of the metabolism could be very low. Conclusion: The test substance undergoes a long process of elimination, has the highest tropism to the elimination organs and undergoes active biotransformation processes in the body of animals

Incommensurately modulated twin structure of nyerereite Na 1.64 K 0.36 Ca(CO 3 ) 2

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