Effects of antioxidants on regeneration of protoplasts of the filamentous fungus Trichoderma reesei 6/16

The relative content of antioxidants in the mycelium of Trichoderma reesei 6/16 obtained by propagation of fungal protoplasts was shown to decrease (as compared to the initial culture taken for preparation of protoplasts) and restored only in the second generation of regenerated mycelium. In this respect, the effects of various antioxidants (β-carotene, ascorbic acid, α-tocopherol, and ionol) on the frequency of regeneration of T. reesei 6/16 protoplasts were studied. β-Carotene increased the viability of fungal protoplasts to the greatest extent. The effect of ascorbic acid depended on the presence of Fe ions. Ionol did not cause any measurable protective effect

СИНТЕЗ ФУНКЦИОНАЛЬНО ЗАМЕЩЕННЫХ ИЗОКСАЗОЛИЛ(ИЗОТИАЗОЛИЛ)ТРИАЗОЛОВ, ОКСАДИАЗОЛОВ И ТИАДИАЗОЛОВ - НОВЫХ БИОАКТИВНЫХ СУБСТАНЦИЙ

Functionally substituted isoxazolyl(isothiazolyl)triazoles, oxadiazoles and thiadiazoles were synthesized on the basis of reactive 5-arylisoxazoles and 4,5-dichloroisothiazoles by successive transformations at position 3 of the heterocycle. The resulting compounds have a high potential of biological activity.На основе реакционноспособных 5-арилизоксазолов и 4,5-дихлоризотиазолов путем последовательных превращений по положению 3 гетероцикла синтезированы функционально замещенные изоксазолил(изотиазолил)триазолы, оксадиазолы и тиадиазолы. Полученные соединения обладают высоким потенциалом биологической активности

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 Néel 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 interaction 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 broad absorption line attributed to Co2+ ion in octahedral coordination with average effective g-factor g=2.40±0.05 at room temperature and show strong divergence of ESR parameters below ~ 150 K, which implies 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

Zigzag antiferromagnetic quantum ground state in monoclinic honeycomb lattice antimonates A3Ni2SbO6 (A=Li, Na)

We present a comprehensive experimental and theoretical study of the electronic and magnetic properties of two quasi-two-dimensional (2D) honeycomb-lattice monoclinic compounds A3Ni2SbO6 (A=Li, Na). Magnetic susceptibility and specific heat data are consistent with the onset of antiferromagnetic (AFM) long range order at low temperatures with Néel temperatures ~ 14 and 16 K for Li3Ni2SbO6 and Na3Ni2SbO6, respectively. The effective magnetic moments of 4.3 Bohr magnetons/f.u. (Li3Ni2SbO6) and 4.4 Bohr magnetons/f.u. (Na3Ni2SbO6) indicate that Ni2+ is in a high-spin configuration (S=1). The temperature dependence of the inverse magnetic susceptibility follows the Curie-Weiss law in the high-temperature region and shows positive values of the Weiss temperature ~ 8 K (Li3Ni2SbO6) and ~12 K (Na3Ni2SbO6) pointing to the presence of non-negligible ferromagnetic interactions, although the system orders AFM at low temperatures. In addition, the magnetization curves reveal a field-induced (spin-flop type) transition below TN that can be related to the magnetocrystalline anisotropy in these systems. These observations are in agreement with density functional theory calculations, which show that both antiferromagnetic and ferromagnetic intralayer spin exchange couplings between Ni2+ ions are present in the honeycomb planes supporting a zigzag antiferromagnetic ground state. Based on our experimental measurements and theoretical calculations we propose magnetic phase diagrams for the two compounds

Methylammonium Polyiodides: Remarkable Phase Diversity of the Simplest and Low-Melting Alkylammonium Polyiodide System

Newly discovered methylammonium polyiodides (MAIx) are unique precursors for innovative solvent-free technologies in perovskite photovoltaics because MAIx are liquids at room temperature and demonstrate high chemical reactivity. We investigated the features of an MAI-I2 system and built up a first phase diagram in wide temperature and composition ranges using data from differential scanning calorimetry, single-crystal X-ray diffraction, and visual thermal analysis. The phase diagram has been found to differ drastically from that of any related systems owing to the unique propensity of methylammonium toward forming a diversity of polyiodides with complicated crystal structures, namely, MAI2, MAI2.67, MAI4, and MAI5.5, found in this system for the first time. The performed density functional theory calculations revealed the crucial role of entropy contributing to the formation of higher methylammonium polyiodides, in good agreement with experimental data. © 2019 American Chemical Society

Strongly canted antiferromagnetic ground state in Cu3 OH 2F4

An unique crystal structure of copper hydroxyl-fluorite, Cu3(OH)2F4, hosts the trimerized chains of both edge-sharing and corner-sharing CuO2F2 plaquettes. The results of the comprehensive study of this compound, including new synthetic route, measurements of specific heat, ac- and dc-susceptibility, pulsed field magnetization, electron spin resonance, muon spin rotation and relaxation and first principles calculations are presented. The data evidence magnetic phase transition at TC = 12.5 K into canted antiferromagnetic state which is due to antisymmetric Dzyaloshinskii-Moriya (DM) exchange interaction. No alteration of DM component stemming from the intrinsic features of the crystal lattice in Cu3(OH)2F4 results in unusually large spontaneous magnetization. At T < TC, the remanence MR constitutes significant portion of saturation magnetization MS which defines the canting angle φ = 4°. © 2018 Elsevier B.V