COMPREHENSIVE ASSESSMENT THE QUALITY OF LIFE IN PATIENTS WITH ESOPHAGEAL ACHALASIA OF III-IV STAGES AFTER EZOPHAGOCARDIOFUNDOPLASTY IN THE DISTANT POSTOPERATIVE PERIOD

The choice of an optimum method of surgical treatment in case of esophageal achalasia of III-IV stage is still a pressing problem. Geller's operation, balloon dilatation and other minimally invasive methods do not allow to achieve the desired effect of smoothing dysphagia. On the other hand, a number of surgeons in case of III-IV stage consider esophageal resection to be more preferable. Due to the attempt to find an optimum method of conservation of the esophagus in case of esophageal achalasia a laparoscopic esophagocardiofundoplasty operation with partial Hill fundoplication was developed. The aim of the research is to assess the long term results of the operation in terms of the quality of life and effectiveness of treatment. The cases of 51 patients suffering from esophageal achalasia of III-IV stage during the period from 2002 to 2016 were included in the research and these cases received special methods developed by the author. The quality of life was assessed with the help of specific questionnaires GERD-HRQL, GIQLI, the dynamics of changes in the weight of the body and the Eckardt scale of indicating the effectiveness of treatment. The results of the research show decrease of indicators on the Eckardt scale from 9.2 ± 0.5 to 1.9 ± 0.2 points, the GERD questionnaire from 17.3 ± 0.8 to 5.9 ± 0.7 points and increase of indicators according to the GIQLI questionnaire from 92.3 ± 1.2 to 122.9 ± 1.5 points and increase in the weight of the body from 22.9 ± 0.6 to 24.7 ± 0.6 kg

Orbitally induced hierarchy of exchange interactions in zigzag antiferromagnetic state of honeycomb silver delafossite Ag3Co2SbO6

We report the revised crystal structure, static and dynamic magnetic properties of quasi-two dimensional honeycomb-lattice silver delafossite Ag3Co2SbO6. The magnetic susceptibility and specific heat data are consistent with the onset of antiferromagnetic long range order at low temperatures with N\'eel temperature TN ~ 21.2 K. In addition, the magnetization curves revealed a field-induced (spin-flop type) transition below TN in moderate magnetic fields. The GGA+U calculations show the importance of the orbital degrees of freedom, which maintain a hierarchy of exchange interaction in the system. The strongest antiferromagnetic exchange coupling was found in the shortest Co-Co pairs and is due to direct and superexchange interactions between the half-filled xz+yz orbitals pointing directly to each other. The other four out of six nearest neighbor exchanges within the cobalt hexagon are suppressed, since for these bonds active half-filled orbitals turned out to be parallel and do not overlap. The electron spin resonance (ESR) spectra reveal a Gaussian shape line attributed to Co2+ ion in octahedral coordination with average effective g-factor g=2.3+/-0.1 at room temperature and shows strong divergence of ESR parameters below 120 K, which imply an extended region of short-range correlations. Based on the results of magnetic and thermodynamic studies in applied fields, we propose the magnetic phase diagram for the new honeycomb-lattice delafossite

Preparation and characterization of metastable trigonal layered MSb2O6 phases (M = Co, Ni, Cu, Zn, and Mg) and considerations on FeSb2O6

MSb2O6 compounds (M = Mg, Co, Ni, Cu, Zn) are known in the tetragonal trirutile forms, slightly distorted monoclinically with M = Cu due to the Jahn-Teller effect. In this study, using a low-temperature exchange reaction between ilmenite-type NaSbO3 and molten MSO4-KCl (or MgCl2-KCl) mixtures, these five compositions were prepared for the first time as trigonal layered rosiaite (PbSb2O6)-type phases. Upon heating, they irreversibly transform to the known phases via amorphous intermediates, in contrast to previously studied isostructural MnSb2O6, where the stable phase is structurally related to the metastable phase. The same method was found to be applicable for preparing stable rosiaite-type CdSb2O6. The formula volumes of the new phases show an excellent correlation with the ionic radii (except for M = Cu, for which a Jahn-Teller distortion is suspected) and are 2-3% larger than those for the known forms although all coordination numbers are the same. The crystal structure of CoSb2O6 was refined via the Rietveld method: P31m, a = 5.1318(3) Å, and c = 4.5520(3) Å. Compounds with M = Co and Ni antiferromagnetically order at 11 and 15 K, respectively, whereas the copper compound does not show long-range magnetic order down to 1.5 K. A comparison between the magnetic behavior of the metastable and stable polymorphs was carried out. FeSb2O6 could not be prepared because of the 2Fe2+ + Sb5+ = 2Fe3+ + Sb3+ redox reaction. This electron transfer produces an additional 5s2 shell for Sb and results in a volume increase. A comparison of the formula volume for the stable mixture FeSbO4 + 0.5Sb2O4 with that extrapolated for FeSb2O6 predicted that the trirutile-type FeSb2O6 can be stabilized at high pressures. © 2017 The Royal Society of Chemistry.The work was supported by the Russian Foundation for Basic Research under the grant 14-03-01122. A. N. V. acknowledges the support in part from the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST (no. K2-2016-066) and by Act 211 of the Government of Russian Federation, contract no. 02.A03.21.0006

Magnetic Properties of A2Ni2TeO6 (A = K, Li): Zigzag Order in the Honeycomb Layers of Ni2+ Ions Induced by First and Third Nearest-Neighbor Spin Exchanges

The static and dynamic magnetic properties and the specific heat of K2Ni2TeO6 and Li2Ni2TeO6 were examined and it was found that they undergo a long-range ordering at TN = 22.8 and 24.4 K, respectively, but exhibit a strong short-range order. At high temperature, the magnetic susceptibilities of K2Ni2TeO6 and Li2Ni2TeO6 are described by a Curie–Weiss law, with Curie-Weiss temperatures Θ of approximately −13 and −20 K, respectively, leading to the effective magnetic moment of about 4.46 ± 0.01 µB per formula unit, as expected for Ni2+ (S = 1) ions. In the paramagnetic region, the ESR spectra of K2Ni2TeO6 and Li2Ni2TeO6 show a single Lorentzianshaped line characterized by the isotropic effective g-factor, g = 2.19 ± 0.01. The energy-mapping analysis shows that the honeycomb layers of A2Ni2TeO6 (A = K, Li) and Li3Ni2SbO6 adopt a zigzag order, in which zigzag ferromagnetic chains are antiferromagnetically coupled, because the third nearest-neighbor spin exchanges are strongly antiferromagnetic while the first nearest-neighbor spin exchanges are strongly ferromagnetic, and that adjacent zigzag-ordered honeycomb layers prefer to be ferromagnetically coupled. The short-range order of the zigzag-ordered honeycomb lattices of K2Ni2TeO6 and Li2Ni2TeO6 is equivalent to that of an antiferromagnetic uniform chain, and is related to the short-range order of the ferromagnetic chains along the direction perpendicular to the chains. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Russian Foundation for Basic Research, РФФИ; Ministry of Education, MOE: 2020R1A6A1A03048004; National Research Foundation of Korea, NRF; Russian Science Foundation, RSF: 22-42-08002; Government Council on Grants, Russian Federation: 075-15-2021-604Funding: This work was supported by the grant 14-03-01122 from the Russian Foundation for Basic Research (VBN), by the Russian Scientific Foundation through Grant No. 22-42-08002, and by the Mega-grant program of the Government of Russian Federation through the project 075-15-2021-604. The work at KHU was financially supported by the Basic Science Research Program through the National Research Foundation (NRF) of Korea, which was funded by the Ministry of Education (2020R1A6A1A03048004)

Synthesis and characterization of MnCrO4, a new mixed-valence antiferromagnet

A new orthorhombic phase, MnCrO4, isostructural with MCrO 4 (M = Mg, Co, Ni, Cu, Cd) was prepared by evaporation of an aqueous solution, (NH4)2Cr2O7 + 2 Mn(NO 3)2, followed by calcination at 400 C. It is characterized by redox titration, Rietveld analysis of the X-ray diffraction pattern, Cr K edge and Mn K edge XANES, ESR, magnetic susceptibility, specific heat and resistivity measurements. In contrast to the high-pressure MnCrO4 phase where both cations are octahedral, the new phase contains Cr in a tetrahedral environment suggesting the charge balance Mn2+Cr 6+O4. However, the positions of both X-ray absorption K edges, the bond lengths and the ESR data suggest the occurrence of some mixed-valence character in which the mean oxidation state of Mn is higher than 2 and that of Cr is lower than 6. Both the magnetic susceptibility and the specific heat data indicate an onset of a three-dimensional antiferromagnetic order at TN ≈ 42 K, which was confirmed also by calculating the spin exchange interactions on the basis of first principles density functional calculations. Dynamic magnetic studies (ESR) corroborate this scenario and indicate appreciable short-range correlations at temperatures far above T N. MnCrO4 is a semiconductor with activation energy of 0.27 eV; it loses oxygen on heating above 400 C to form first Cr 2O3 plus Mn3O4 and then Mn 1.5Cr1.5O4 spinel. © 2013 American Chemical Society

Static and dynamic magnetic response of fragmented haldane-like spin chains in layered Li3Cu2SbO6

The structure and the magnetic properties of layered Li3Cu2SbO6 are investigated by powder X-ray diffraction, static susceptibility, and electron spin resonance studies up to 330 GHz. The XRD data experimentally verify the space group C2=m with halved unit cell volume in contrast to previously reported C2=c. In addition, the data show significant Li=Cuintersite exchange. Static magnetic susceptibility and ESR measurements show two magnetic contributions, i.e., quasifree spins at low-temperature and a spin-gapped magnetic subsystem, with about half of the spins being associated to each subsystem. The data suggest ferromagnetic-antiferromagnetic alternating chains with JFM = -285 K and JAFM = 160 K with a significant amount of Li-defects in the chains. The results are discussed in the scenario of fragmented 1D S = 1 AFM chains with a rather high defect concentration of about 17% and associated S =1=2 edge states of the resulting finite Haldane chains. © 2016 The Physical Society of Japan