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141.
Svitlana V. Shishkina Irina S. Konovalova Svitlana S. Kovalenko Lyudmila L. Nikolaeva Natalya D. Bunyatyan Sergiy M. Kovalenko 《Acta Crystallographica. Section C, Structural Chemistry》2021,77(1):20-28
The dipharmacophore compound 3‐cyclopropyl‐5‐(3‐methyl‐[1,2,4]triazolo[4,3‐a]pyridin‐7‐yl)‐1,2,4‐oxadiazole, C12H11N5O, was studied on the assumption of its potential biological activity. Two polymorphic forms differ in both their molecular and crystal structures. The monoclinic polymorphic form was crystallized from more volatile solvents and contains a conformer with a higher relative energy. The basic molecule forms an abundance of interactions with relatively close energies. The orthorhombic polymorph was crystallized very slowly from isoamyl alcohol and contains a conformer with a much lower energy. The basic molecule forms two strong interactions and a large number of weak interactions. Stacking interactions of the `head‐to‐head' type in the monoclinic structure and of the `head‐to‐tail' type in the orthorhombic structure proved to be the strongest and form stacked columns in the two polymorphs. The main structural motif of the monoclinic structure is a double column where two stacked columns interact through weak C—H…N hydrogen bonds and dispersive interactions. In the orthorhombic structure, a single stacked column is the main structural motif. Periodic calculations confirmed that the orthorhombic structure obtained by slow evaporation has a lower lattice energy (0.97 kcal mol?1) compared to the monoclinic structure. 相似文献
142.
Irina O. Zhuravel Oleg V. Zaremba Oleksandr S. Detistov Svitlana S. Kovalenko Valentin P. Chernykh 《合成通讯》2013,43(21):3778-3784
New 5-hydroxymethyl-8-methyl-3-(3-aryl-[1,2,4]oxadiazol-5-yl)-2H-pyrano-[2,3-c]pyridin-2-ones and their esters were synthesized. The structure of obtained compounds was determined through a complete 1H NMR analysis. 相似文献
143.
V. N. Karpinskii N. G. Kondrat’ev A. L. Osipenkov V. G. Karavaev N. A. Filippov G. V. Trubnikov A. D. Kovalenko A. O. Sidorin A. V. Butenko V. I. Volkov B. V. Vasilishin A. E. Kirichenko S. V. Romanov 《Physics of Particles and Nuclei Letters》2010,7(7):517-521
One of the trends of Nuclotron development lies in modifying the power supply system and upgrading the energy evacuation system of structural magnets in order to provide reliable durable operation of the synchrotron at a dipole magnet field level of 2 T. This is necessary for Nuclotron operation as part of the injection chain of the heavy-ion NICA collider under design at JINR and for the current program of physical studies. The principles of construction and specific features of the existing system based on a separate power supply of structural dipole and quadrupole magnetic elements are considered. The main provisions of the upgrade of the power supply system, structural and schematic diagrams, control schemes, and energy evacuation switch schemes from superconducting elements are presented. 相似文献
144.
Marcel Aebli Bogdan M. Benin Kyle M. McCall Viktoriia Morad Debora Thöny Hansjörg Grützmacher Maksym V. Kovalenko 《Helvetica chimica acta》2020,103(7):e2000080
Inorganic lead halide perovskites have gained immense scientific interest for optoelectronic applications. In this work, we present a one-dimensional polymorph of cesium lead bromide (δ-CsPbBr3) synthesized through a simple anion-exchange reaction, wherein distorted edge-sharing PbBr6 octahedra form 1D chains isolated by Cs ions. δ-CsPbBr3 was characterized by Raman spectroscopy, X-ray diffraction, 207Pb and 133Cs solid-state NMR, and by optical emission and absorption spectroscopies. This non-perovskite material irreversibly transforms into the well-known three-dimensional perovskite phase (γ-CsPbBr3) upon heating to above 151 °C. The indirect bandgap was determined by absorption measurements and calculation to be 2.9 eV. δ-CsPbBr3 exhibits broadband yellow photoluminescence with a quantum yield of 3.2 %±0.2 % at room temperature and 95 %±5 % at 77 K, and this emission is attributed to the recombination of self-trapped excitons. This study emphasizes that the metastable δ-CsPbBr3 may be a persistent, concomitant phase in Cs−Pb-Br-containing materials systems, such as those used in solar cells and LEDs, and it showcases the characterization tools used for its detection. 相似文献
145.
Valentina Georgievna Ponomareva Elena Sergeevna Shutova Konstantin Aleksandrovich Kovalenko Vladimir Petrovich Fedin 《Molecules (Basel, Switzerland)》2022,27(23)
New (1−x)CsH2PO4–xUiO-66 electrolytes with high proton conductivity and thermal stability at 230–250 °C were developed. The phase composition and proton conductivity of nanocomposites (x = 0–0.15) were investigated in detail. As shown, the UiO-66 matrix is thermally and chemically suitable for creating composites based on CsH2PO4. The CsH2PO4 crystal structure remains, but the degree of salt crystallinity changes in nanocomposites. As a result of interface interaction, dispersion, and partial salt amorphization, the proton conductivity of the composite increases by two orders of magnitude in the low-temperature range (up to 200 °C), depending on the UiO-66 fraction, and goes through a maximum. At higher temperatures, up to 250 °C, the conductivity of nanocomposites is close to the superprotonic values of the original salt at low UiO-66 values; then, it decreases linearly within one order of magnitude and drops sharply at x > 0.07. The stability of CsH2PO4-UiO-66 composites with high proton conductivity was shown. This creates prospects for their use as proton membranes in electrochemical devices. 相似文献
146.
L. Ya. Zakharova F. G. Valeeva A. R. Ibragimova L. A. Kudryavtseva Yu. F. Zuev L. V. Avvakumova V. I. Kovalenko A. I. Konovalov 《Russian Chemical Bulletin》2007,56(1):62-69
The kinetics of alkaline hydrolysis of O-ethyl O-p-nitrophenyl chloromethylphosphonate in a sodium bis(2-ethylhexyl)sulfosuccinate—n-nonane—polyethylene glycol—water reverse micellar system was studied in a wide range of concentrations of the surfactant
and water. The sign of the catalytic effect of micelles is inverted in the presence of the polymer. A sharp change in the
apparent rate constant of hydrolysis of the phosphonate was found in a region of the temperature percolation threshold.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 60–67, January, 2007. 相似文献
147.
I. Štekl P. Čermák P. Beneš V. B. Brudanin K. N. Gusev V. G. Egorov A. A. Klimenko V. E. Kovalenko A. Kovalík N. I. Rukhadze A. V. Salamatin V. V. Timkin Ts. Vylov Ch. Briançon F. Šimkovic 《Czechoslovak Journal of Physics》2006,56(5):505-510
Present status of the experiment TGV II which is devoted to the measurement of double-beta decay of 106Cd is given. The low background spectrometer TGV II is installed in the Modane Underground Laboratory and has been running
from February 2005 with approx 10 grams of 106Cd enriched at 75%. After an analysis of 3736 hours of experimental data the new improved half-life limit for 2νEC/EC decay of 106Cd (0
g.s.
+
→ 0
g.s.
+
) is given as T
1
2/2ν
> 4.8 × 1019 years (90% CL). The search for 2νEC/EC decay of 106Cd to the excited states of 106Pd allows to determine the limits of the half-lives T
1
2/2ν
(0
g.s.
+
→ 2
1
+
) > 3.9 × 1019 years (90% CL) and T
1
2/2ν
(0
g.s.
+
→ 0
1
+
) > 5.8 × 1019 years (90% CL).
Presented by I. Štekl at the Workshop on calculation of double-beta-decay matrix elements (MEDEX’05), Corfu, Greece, September
26–29, 2005. 相似文献
148.
Laura Kovalenko Martin W. Schr der R. Amaranatha Reddy Siegmar Diele Gerhard Pelzl Wolfgang Weissflog 《Liquid crystals》2005,32(7):857-865
New five-ring bent-core mesogens derived from 4-cyanoresorcinol as the central core have been synthesized. The mesophases were assigned by polarizing microscopy, X-ray diffraction and electro-optical measurements. It was found that the mesophase behaviour clearly depends on the direction of the carboxyl linking groups between the aromatic rings. If the outer and inner ester linking groups of a wing are in the same direction then nematic phases and, for long chain members, SmC and SmCPA phases are observed. If the outer and inner linking groups are in opposing directions a dimorphism, SmA-SmAPA, is observed and the clearing temperatures are increased by about 55 K. It is remarkable that in the SmCPA phases of the first series, polar switching preferably takes place through a collective rotation of the molecules around their long axes which is accompanied by the inversion of the chirality of the smectic layers. 相似文献
149.
Films of polyvinylidene fluoride with tetrafluoroethylene several micron thick were prepared by vacuum electron-beam evaporation
in a static electric field. It is shown that a polymer deposited on a negative electrode possesses a structure similar to
that of uniaxially stretched and polarized films and has a high (up to 85%) content of the piezoactive β phase. The electromechanical coupling coefficient k
33 and the pyrosensitivity of these samples are substantially higher than those of layers deposited under the same conditions
in the absence of a field.
Zh. Tekh. Fiz. 68, 101–103 (December 1998) 相似文献
150.
V. V. Tarasov N. F. Kovalenko Dongxiang Zhang E. G. Sorokin 《Russian Journal of Applied Chemistry》2008,81(12):2122-2126
Coalescence of KHA-30 compressor oil microdroplets on a carbon fabric, aimed to remove them from air and water streams used for compressor cooling, was examined. 相似文献