Revealing the Complex Nature of Bonding in the Binary High-Pressure Compound FeO_{2}.

Extreme pressures and temperatures are known to drastically affect the chemistry of iron oxides, resulting in numerous compounds forming homologous series nFeOmFe_{2}O_{3} and the appearance of FeO_{2}. Here, based on the results of in situ single-crystal x-ray diffraction, Mössbauer spectroscopy, x-ray absorption spectroscopy, and density-functional theory+dynamical mean-field theory calculations, we demonstrate that iron in high-pressure cubic FeO_{2} and isostructural FeO_{2}H_{0.5} is ferric (Fe^{3+}), and oxygen has a formal valence less than 2. Reduction of oxygen valence from 2, common for oxides, down to 1.5 can be explained by a formation of a localized hole at oxygen sites.

Nanodomain structure of single crystalline nickel oxide.

In this work we present a comprehensive study of the domain structure of a nickel oxide single crystal grown by floating zone melting and suggest a correlation between point defects and the observed domain structure. The properties and structure of domains dictate the dynamics of resistive switching, water splitting and gas sensing, to name but a few. Investigating the correlation between point defects and domain structure can provide a deeper understanding of their formation and structure, which potentially allows one to tailor domain structure and the dynamics of the aforementioned applications. A range of inhomogeneities are observed by diffraction and microscopy techniques. X-ray and low-energy electron diffraction reveal domains on the submicron- and nanometer-scales, respectively. In turn, these domains are visualised by atomic force and scanning tunneling microscopy (STM), respectively. A comprehensive transmission electron microscopy (TEM) study reveals inhomogeneities ranging from domains of varying size, misorientation of domains, variation of the lattice constant and bending of lattice planes. X-ray photoelectron spectroscopy and electron energy-loss spectroscopy indicate the crystal is Ni deficient. Density functional theory calculations-considering the spatial and electronic disturbance induced by the favourable nickel vacancy-reveal a nanoscale distortion comparable to STM and TEM observations. The different inhomogeneities are understood in terms of the structural relaxation induced by ordering of nickel vacancies, which is predicted to be favourable.

[Diagnostic and Prognostic Markers of Chronic Heart Failure in Patients with Occupational Chronic Obstructive Pulmonary Disease].

Aim      Heart failure (HF) and chronic obstructive pulmonary disease (COPD) are a common comorbidity. Professional chronic obstructive pulmonary disease (PCOPD) is a specific phenotype, which suggests peculiarities in the development of HF. Difficulties of HF diagnosis in such patients determine the relevance of searching for additional markers. The aim of the study was identifying HF markers in patients with PCOPD.Material and methods  This single-site, cohort, prospective, observational study included 345 patients. The main group consisted of PCOPD patients; the comparison group consisted of patients with COPD induced by tobacco smoking; and the control group included conventionally healthy individuals. The groups were matched by the index of coincidence; pairs were matched at 1:1 by the "nearest neighbor index"; covariates for matching included COPD duration, sex, and age. Each group included 115 patients. The major professional adverse factors were silica-containing dust and organic solvents. COPD was diagnosed according to GOLD criteria; HF was diagnosed in accordance with Russian clinical guidelines. The markers were determined by multifactorial logistic regression. Likelihood of events with allowance for the time to the event was analyzed by the Kaplan-Meier method.Results HF in PCOPD patients was characterized by biventricular damage, preserved left ventricular ejection fraction, and frequent hospitalizations for decompensation (17.5 % vs. 9.5 % for COPD in smokers). HF markers in patients with PCOPD included the length of work of more than 20 years, pulmonary artery systolic pressure (PASP) higher than 35 mm Hg according to data of Doppler echocardiography, diffusing capacity of lungs for carbon monoxide (DLCO) less than 50 %, increased serum concentrations of CC-chemokine ligand 18 (CCL18), S-100­beta protein, and N-terminal pro-brain natriuretic peptide (NT-pro-BNP). Diagnostic sensitivity of the multifactorial model was 84 % and specificity was 81 %. Two models were proposed for purposes of screening, which included the following parameters: length of work, exposure to aromatic hydrocarbons, decreased distance in 6-min walk test by more than 60 m per year and length of work, exposure to inorganic dust, and decreased forced expiratory volume during the first second by more than 55 ml per year.Conclusion      The markers for development of HF in PCOPD patients are length of work >20 years, PASP >35 mm Hg, DLCO <50 %, and increased serum concentrations of CCL18, S-100­beta protein, and NT-pro-BNP.

Fe-N system at high pressure reveals a compound featuring polymeric nitrogen chains.

Poly-nitrogen compounds have been considered as potential high energy density materials for a long time due to the large number of energetic N-N or N=N bonds. In most cases high nitrogen content and stability at ambient conditions are mutually exclusive, thereby making the synthesis of such materials challenging. One way to stabilize such compounds is the application of high pressure. Here, through a direct reaction between Fe and N2 in a laser-heated diamond anvil cell, we synthesize three ironnitrogen compounds Fe3N2, FeN2 and FeN4. Their crystal structures are revealed by single-crystal synchrotron X-ray diffraction. Fe3N2, synthesized at 50 GPa, is isostructural to chromium carbide Cr3C2. FeN2 has a marcasite structure type and features covalently bonded dinitrogen units in its crystal structure. FeN4, synthesized at 106 GPa, features polymeric nitrogen chains of [N42-]n units. Based on results of structural studies and theoretical analysis, [N42-]n units in this compound reveal catena-poly[tetraz-1-ene-1,4-diyl] anions.

[The spectrum of human chromosomal aberrations detected by routine and differential (GTG) staining]. / Spektr khromosomnykh aberratsii cheloveka pri rutinnom i differentsial'nom (GTG) okrashivaniiakh.

As a result of sample cytogenetic studies of 23 persons living on the territory of Yamal-Nentsy Autonomous District and chronically exposed to the small doses of radiation the data on the frequency and spectrum of chromosome aberrations, detected by the routine and differential (GTG) staining were obtained. Comparative efficiency of these methods was determined. The absence of significant differences for the spectrum and frequencies of chromosome aberrations revealed by both methods was shown.