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71.
Dmitrii O. Kharchenko Olga M. Shchokotova Vasyl O. Kharchenko Viktor V. Kupriienko S.V. Kokhan Xiaoyong Wu 《辐射效应与固体损伤》2020,175(7-8):602-626
ABSTRACT We study microstructure transformation in Zr–Nb system under neutron irradiation and its mechanical properties change under mechanical loads in a form of shear deformation by using phase field methodology. The developed phase field approach takes into account defects dynamics based on reaction rate theory and elastic contribution to study mechanical properties change. A numerical modeling is provided in three stages: sample preparation, irradiation of the prepared sample and mechanical loading of the irradiated sample. A precipitation of β-Niobium particles of the size of several nanometers is discussed. Results of phase field modeling indicate that β-Niobium particles grow slowly during irradiation due to point defects rearrangement. Statistical analysis of dynamics of radiation-induced microstructure transformations is provided. Simulation results of shear deformation of pre-irradiated and post-irradiated alloys are discussed. Maps of local distribution of strain and stress and strain–stress curves are obtained. Results are verified with experimental data. 相似文献
72.
Superbase‐catalyzed domino 3H‐pyrroles synthesis from ketoximes and acetylene: DFT study vs experiment
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Elimination of vinyl alcohol from 5‐vinyloxypyrrolines in the presence of superbases (final step of domino 3H‐pyrroles synthesis from ketoximes and acetylene) is studied computationally at different levels of theory in DMSO solution (PCM). The sequences of transformations starting from nucleophilic addition of hydroxide ion to carbon‐carbon or carbon‐nitrogen double bonds are proposed as possible mechanisms. Unusual reactivity of 2,5‐dimethylphenyl substituted 5‐vinyloxypyrroline is explained within these mechanisms. 相似文献
73.
Dmitrii Semenok Alexey Kletskov Evgenij Dikusar Vladimir Potkin Oleg Lukin 《Tetrahedron letters》2018,59(4):372-374
A library of 4′-chloro- and 4′-fluorosulfonyl-substituted chalcones was prepared via the aldol-type condensation reactions of 4-acetylbenzene-1-sulfonyl halides with various aromatic aldehydes, either in absolute ethanol or glacial acetic acid, in the presence of dry HCl. This represents the first examples of chalcone sulfonyl halides in which the phenone ring bears one of these functional groups. The reactivity of the chalcone sulfonyl halides were strongly dependent on the styrene ring substituents; sulfonyl chlorides reacted with most nucleophiles (e.g. amines, alcohols), while sulfonyl fluorides reacted only with charged nucleophiles (e.g. phenolates). 相似文献
74.
Demkiv O Smutok O Paryzhak S Gayda G Sultanov Y Guschin D Shkil H Schuhmann W Gonchar M 《Talanta》2008,76(4):837-846
Novel formaldehyde-selective amperometric biosensors were developed based on NAD(+)- and glutathione-dependent formaldehyde dehydrogenase isolated from a gene-engineered strain of the methylotrophic yeast Hansenula polymorpha. Electron transfer between the immobilized enzyme and a platinized graphite electrode was established using a number of different low-molecular free-diffusing redox mediators or positively charged cathodic electrodeposition paints modified with Os-bis-N,N-(2,2'-bipyridil)-chloride ([Os(bpy)(2)Cl]) complexes. Among five tested Os-containing redox polymers of different chemical structure and properties, complexes of osmium-modified poly(4-vinylpyridine) with molecular mass of about 60 kDa containing diaminopropyl groups were selected. The positively charged cathodic paint exhibited the best electron-transfer characteristics. Moreover, the polymer layers simultaneously served as a matrix for keeping the negatively charged low-molecular cofactors, glutathione and NAD(+), in the bioactive layer. Additionally, covering the enzyme/polymer layer with a negatively charged Nafion membrane significantly decreased cofactors leakage and simultaneously enhanced the sensor' stability. The developed sensors revealed a high selectivity to formaldehyde (FA) and a low cross-sensitivity to other substances (such as, e.g. butyraldehyde, propionaldehyde, acetaldehyde, methylglyoxal). The maximum current value was 34.2+/-0.72 microA/mm(2) (3.05 mm diameter electrode) and the apparent Michaelis-Menten constant (K(M)(app)) derived from the FA calibration curves was 120+/-5mM with a linear detection range for FA up to 20mM. The best observed sensitivity for reagentless sensor was 1.8 nA microM(-1) (358 Am(-2)M(-1)). The developed sensors had a good operational and storage stability. The laboratory prototype of the sensor was applied for FA testing in some real samples of pharmaceutical (formidron), disinfectant (descoton forte) and industrial product (formalin). A good correlation was revealed between the concentration values measured using the developed FdDH-based sensor, an enzymatic method and standard chemical methods of FA determination. 相似文献
75.
Nicolay Yu. Adonin Dmitrii E. Babushkin Vadim V. Bardin Vasiliy I. Mashukov 《Tetrahedron》2008,64(25):5920-5924
The effect of N-heterocyclic carbene (NHC) ligands on the catalytic activity of in situ generated palladium complexes in the model cross-coupling reaction of K[C6F5BF3] with 4-FC6H4I was studied. Based on the obtained results, a series of pentafluorobiphenyls C6F5C6H4X were prepared from K[C6F5BF3] and XC6H4I or 4-CF3C6H4Br in high yields under aerobic conditions. 相似文献
76.
Wanli Nie Wenqing Xu Maxim V. Borzov Dmitrii P. Krut’ko Judith A.K. Howard 《Journal of organometallic chemistry》2008,693(13):2355-2368
The novel bidentate ligand, C5H4CPh2CH2-(1-Me-C3H4N2) (3), has been prepared and characterized as its lithium salt LiC5H4CPh2CH2-(1-Me-C3H4N2) (3-Li). Cyclopentadiene HC5H4CPh2CH2-(1-Me-C3H4N2) (3-H) has been obtained from 6,6-diphenylfulvene and 1,2-dimethylimidazoline (1). In THF-d8 solution in the presence of 1, (1-methylimidazoline-2-yl)methyllithium (2) has been proved to undergo gradual conversion into a dilithium derivative of N1-methyl-N2-[(1E,2E)-1-methyl-2-(1-methylimidazolidine-2-idene)ethylidene]ethane-1,2-diamine (2a). In a solution, cyclopentadiene 3-H has been shown to undergo isomerization into 3-{N-[2-(N-methylamino)ethyl]amino}-1,1-diphenyl-1,2-dihydropentalene (4) and, further, into a mixture of 4 and two rotameric 3-[N-(2-aminoethyl)-N-methylamino]-1,1-diphenyl-1,2-dihydropentalenes (5a) and (5b). Treatment of the lithium salt 3-Li with Me3SiCl has lead to 3-{N-[2-(N-trimethylsilylamino)ethyl]amino}-1,1-diphenyl-1,2-dihydropentalene (6) as the dominant component in the reaction mixture. In the latter case the expected Me3Si-C5H4CPh2CH2-(1-Me-C3H4N2) (3-Si) was not observed. Stannylation of 3-Li with 1 equiv. of Me3SnCl has resulted in formation of a mixture of Me3Sn-C5H4CPh2CH2-(1-Me-C3H4N2) (3-Sn), (Me3Sn)2-C5H3CPh2CH2-(1-Me-C3H4N2) (3-Sn2), and cyclopentadiene 3-H in a ca. 2:1:1 molar ratio. Monocyclopentadienyl complexes {[η5:η1-κN-C5H4CPh2CH2-(1-Me-C3H4N2)]MCl3 (M = Ti (7), Zr (8)) have been prepared starting from the organotin and organolithium compounds 3-Sn and 3-Li, respectively. The dynamic behavior of complexes 7 and 8 has been investigated by means of variable-temperature NMR spectroscopy in solutions. The molecular structures of the dihydropentalene 4, binuclear complex {[η5:η1-κN-C5H4CPh2CH2-(1-Me-C3H4N2)]ZrCl2}2(μ-Cl)28, and a coordination dimer of the dilithium salt 2a have been established by X-ray diffraction analysis. In the crystal structure of the 2a-dimer, the shortest known Li-Li contact has been found. 相似文献
77.
Ilya Kolesnikov Daria Mamonova Dmitrii Pankin Gulia Bikbaeva Anastasia Khokhlova Anna Pilip Anastasia Egorova Vladislav Zigel Alina Manshina 《Photochemistry and photobiology》2023,99(3):929-935
Modern progress in photopharmocology calls for new generation of compounds joining bioactivity, photoswitchable properties and high selectivity of response to light wavelength. Introduced here, phosphonate–fullerene hybrids are the first representatives of such compounds. Phosphonate–fullerene hybrids were synthesized on a base of fullerene C60 and organophosphates with the function of photoswitchable cholinesterase activity—phosphorylated thiazolotriazole and aminomalonate compounds and studied with FTIR, UV–VIS spectroscopy and IPC-micro neurotoxin amperometric analysis. As a result of spectroscopic and bioactivity characterization, it was not only demonstrated butyrylcholinesterase (BuChE) inhibition increase in phosphonate–fullerene hybrids compared with pure phosphonates but also pronounced response of inhibition degree to laser irradiation of hybrids. It was found opposite behavior of hybrids as a result of laser irradiation—BuChE inhibition drop-off for thiazolotriazole–fullerene and pronounced growth for aminomalonate–fullerene. The other remarkable peculiarity of presented phosphonate–fullerene hybrids is high selectivity of inhibition change degree to laser wavelength (266 or 325 nm). 相似文献
78.
Nikonova OA Jansson K Kessler VG Sundberg M Baranov AI Shevelkov AV Drobot DV Seisenbaeva GA 《Inorganic chemistry》2008,47(4):1295-1300
Anodic oxidation of rhenium in ethanol in the presence of LiCl as a conductive additive results with high yield in formation of a new oxoethoxide cluster, Re(4)O(4)(OEt)(12). The structure of the planar centrosymmetric metal-oxygen core of this molecule is composed of four edge-sharing Re(V)O(6) octahedra. Eight electrons are available for the formation of metal-metal bonds indicated by five relatively short Re-Re distances within the Re 4-rhombus, a "planar butterfly" type cluster. The theoretical calculations are indicating relatively low contribution of metal-metal bonding in the stability of the core. The stability of the +V-oxidation state, unusual for rhenium alkoxides can be at least partially attributed to the size effects in the packing of ligands. The X-ray powder study indicates that treatment of Re(4)O(4)(OEt)(12). in ambient atmosphere rapidly transforms it into a mixed-valence derivative Re(4)O(6)(OEt)(10) with a structure related to the earlier investigated cluster Re(4)O(6)(O(i)Pr)(10). Thermal decomposition of the latter rhenium oxoethoxide results in reduction to rhenium metal at as low temperatures as 380 degrees C, producing aggregates of metal nanoparticles with the average size of 3 nm. 相似文献
79.
Clair S Variola F Kondratenko M Jedrzejowski P Nanci A Rosei F Perepichka DF 《The Journal of chemical physics》2008,128(14):144705
Surface modification of titanium and its alloys is of great importance for their practical application as biomedical implants. We have studied and compared assembly of dodecylphosphoric acid on commercial polished and on nanostructured titanium disks. The latter were produced by chemical etching that created nanoscale pits of typical size of about 20 nm. Enhanced hydrophobicity and high molecular density were obtained after functionalization of the nanotextured substrate. Aging tests showed a lifetime of the organic films of about one month in phosphate buffer. The samples were characterized by means of infrared spectroscopy, contact angle measurements, ellipsometry, and atomic force and scanning tunneling microscopies. 相似文献
80.