337 results match your criteria: "Taras Shevchenko University[Affiliation]"

Using the transmission electron microscopy (TEM)/high-resolution TEM (HRTEM) and selected area electron diffraction (SAED) methods, it was shown that the nanocolloids of ZnO contain hydrolyzed ZnO nanoparticles (NPs). Typically, the nanocrystalline ZnO/Zn(OH) core is covered by an amorphous shell of zinc hydroxides, preventing the encapsulated crystal core from dissolving. Similar studies were carried out with TiO nanocolloids.

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Light absorption by interacting atomic gas in quantum optical regime.

J Chem Phys

July 2021

Quantum and Laser Science (HIR Building) Department of Physics, University of Malaya, 50603 Kuala Lumpur, Malaysia.

Quantum optical theory of absorption properties of interacting atoms is developed. The concept of local absorptance is introduced as a derivative of the logarithm of intensity with respect to the distance in the vicinity of a given spatial point and a moment of time. The intensity is represented by the quantum and statistically averaged normal product of creation and annihilation operators of the electromagnetic field.

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A simple sensitive method for nonspecific recognition of armagnac, cognac, whiskey, and ethanol/water mixture was developed by using photoluminescence (PL) of carbon nanoparticles (NPs). The carbon NPs were synthesized from the mixture of urea and anhydrous citric acid, followed by few annealing processes to achieve the full effect by solvothermal carbonization. PL features of carbon NPs depend on the alcohol environments in which the NPs are dispersed.

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The third generation Buchwald precatalysts Pd(ABP)(Phos)(OMs) (also known as Phos Pd G3)) with XPhos and RuPhos were prepared in multigram scale by a modified procedure (ABP = fragment of C-deprotonated 2-aminobiphenyl, XPhos = 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl, RuPhos = 2-dicyclohexylphosphino-2',6'-diisopropoxybiphenyl, OMs = CHSO). The H- and P-NMR spectra of the title complexes and some impurities, measured by various 1D and 2D techniques, were analyzed in detail. The solvent-dependent isomerization of Pd(ABP)(XPhos)(OMs) was studied by NMR, and the X-ray structures of two isomers were determined.

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Objective: The aim: The article presents the theoretical substantiation of the value-motivational component of a healthy lifestyle, the diagnostic procedure, the results of quantitative and qualitative analysis of the real state of its formation in students of modern universities; the pedagogical tools of health-oriented, containing interactive and reflexively oriented forms and methods of educating a healthy lifestyle are presented; specific examples of their implementation are given.

Patients And Methods: Materials and methods: A set of general scientific methods (analysis, synthesis, comparison, systematization, generalization) and diagnostic standardized methods (M. Rokich's "Value orientations" method, R.

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A Cu-catalyzed, easily scalable one-pot synthesis of fused pyridines by the reaction of cyclic ketones with propargylamine is described. The protocol was optimized based on the results of more than 30 experiments. The highest product yields were achieved in -PrOH as a solvent in the presence of 5.

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The title compound, {[KNi(CHNO)]·4.8HO} , was obtained as a result of a template reaction between oxalohydrazide-hydroxamic acid, formaldehyde and nickel(II) nitrate followed by partial hydrolysis of the formed inter-mediate. The two independent [Ni(CHNO)] complex anions exhibit pseudo- symmetry and consist of an almost planar metal-containing fragment and a 1,3,5-oxadiazinane ring with a chair conformation disposed nearly perpendicularly with respect to the former.

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Article Synopsis
  • The study investigates the short-range order in liquid silicon (Si), germanium (Ge), and their binary alloys using x-ray diffraction and simulations, focusing on supercooled states.
  • The experiments employed advanced techniques like aerodynamic levitation and CO2 laser heating to achieve deeper supercooling than previous studies.
  • Findings reveal that the local atomic structure of these liquids resembles the-tin structure, showing consistent coordination numbers, but developing tetrahedral ordering suggests a transition from a high-density liquid phase to a lower-density phase akin to diamond structure.
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  • Endogenous cytokinins in medicinal mushrooms Hericium coralloides and Fomitopsis officinalis were identified using advanced chromatography techniques, revealing species-specific traits especially high levels of zeatin-type cytokinins and isopentenyladenine.
  • Purified cytokinin fractions from both mushroom species displayed cytotoxic effects on HepG2 tumor cells, promoting increased apoptosis and glucose uptake, with H. coralloides exhibiting more pronounced effects compared to F. officinalis.
  • The study suggests that the extraction methods of cytokinins are crucial for developing pharmacologically active drugs, highlighting the potential of these mushroom extracts as anticancer agents.
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Reaction of 2,2'-bipyridine (2,2'-bipy) or 1,10-phenantroline (phen) with [Mn(Piv)(EtOH)] led to the formation of binuclear complexes [Mn(Piv)L] (L = 2,2'-bipy (), phen (); Piv is the anion of pivalic acid). Oxidation of or by air oxygen resulted in the formation of tetranuclear Mn complexes [MnO(Piv)L] (L = 2,2'-bipy (), phen ()). The hexanuclear complex [Mn(OH)(Piv)(pym)] () was formed in the reaction of [Mn(Piv)(EtOH)] with pyrimidine (pym), while oxidation of produced the coordination polymer [MnO(Piv)(pym)] ().

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The Central Asian species of the winter moth genus Phthorarcha Meyrick, 1892 are revised and some specimens of the type series of Phthorarcha primigena Staudinger, 1895 are separated and described as Phthorarcha haberhaueri, sp. nov. These poorly known moths and their male and female genitalia are described and illustrated and discrimination of the genera Phthorarcha, Alsophiloides Inoue and Chimaphila Nakajima Wang is analysed.

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  • The reaction of copper nitrate with succinic acid and TMEDA in a basic solution creates a complex structure known as poly[[[(,,','-tetra-methyl-ethylenedi-amine-κ ,')copper(II)]-μ-succinato-κ : ] tetra-hydrate].
  • The succinate ligands connect to copper atoms in a monodentate manner, leading to a distorted square-planar geometry and forming one-dimensional polymeric chains.
  • Hydrogen bonds between the ligands and water molecules help organize these chains into parallel sheets, with Hirshfeld surface analysis used to study the intermolecular interactions within the structure.
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Thermochromic Meltable Materials with Reverse Spin Transition Controlled by Chemical Design.

Angew Chem Int Ed Engl

October 2020

Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, 46980 Paterna, Valencia, Spain.

We report a series of meltable Fe complexes, which, depending on the length of aliphatic chains, display abrupt forward low-spin to high-spin transition or unprecedented melting-triggered reverse high-spin to low-spin transition on temperature rise. The reverse spin transition is perfectly reproducible on thermal cycling and the obtained materials are easily processable in the form of thin film owing to their soft-matter nature. We found that the discovered approach represents a potentially generalizable new avenue to control both the location in temperature and the direction of the spin transition in meltable compounds.

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The key feature of photon echo-based spectroscopies is a selective elimination of the inhomogeneous broadening. Fast homogeneous dephasing typical for large macromolecules makes it difficult to resolve the congested spectra even if the inhomogeneous component is eliminated. We propose a novel two-dimensional spectroscopy in which a series of temporally separated probe pulses are combined with the strong narrowband control pulse.

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Crystal structure and Hirshfeld surface analysis of diethyl 5-(2-cyano-phen-oxy)isophthalate.

Acta Crystallogr E Crystallogr Commun

June 2020

Department of Chemistry, National Taras Shevchenko University, Volodymyrska Street 64, 01601 Kyiv, Ukraine.

The title compound, CHNO, obtained by ether bond formation between the reagents, crystallizes in the monoclinic space group 2/. The compound is non-planar, subtending a dihedral angle of 82.38 (4)° between the plane of hy-droxy isophthalate-based ester and that of the benzo-nitrile moiety.

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Crystal structure and Hirshfeld surface analysis of 1,3-diethynyladamantane.

Acta Crystallogr E Crystallogr Commun

June 2020

Inorganic Chemistry Department, National Taras Shevchenko University of Kyiv, Volodymyrska Str. 64/13, 01601 Kyiv, Ukraine.

The title compound, CH, exhibits exceptionally weak inter-molecular C-H⋯π hydrogen bonding of the ethynyl groups, with the corresponding H⋯π separations [2.91 (2) and 3.12 (2) Å] exceeding normal vdW distances.

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In the structure of the title salt, (CHN)[VOF], second-order Jahn-Teller distortion of the coordination octa-hedra around V ions is reflected by coexistence of short V-O bonds [1.5767 (12) Å] and -positioned long V-F bonds [2.0981 (9) Å], with four equatorial V-F distances being inter-mediate in magnitude [1.

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Molecular crystals exhibiting polar symmetry are important paradigms for developing new electrooptical materials. Though accessing bulk polarity still presents a significant challenge, in some cases it may be rationalized as being associated with the specific molecular shapes and symmetries and subtle features of supramolecular interactions. In the crystal structure of 3,5,7-trinitro-1-azaadamantane, CHNO, the polar symmetry of the molecular arrangement is a result of complementary prerequisites, namely the C symmetry of the molecules is suited to the generation of polar stacks and the inherent asymmetry of the principal supramolecular bonding, as is provided by NO(lone pair).

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The asymmetric unit of the title compound, CHNO·CHNOS, contains one cation and one anion. The 6-methyl-2,2,4-trioxo-2,4-1,2,3-oxa-thia-zin-3-ide anion adopts an envelope conformation with the S atom as the flap. In the crystal, the anions and cations are held together by N-H⋯O, N-H⋯N, O-H⋯O and C-H⋯O hydrogen bonds, thus forming a three-dimensional structure.

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Experimental and Computational Studies of the Structure of CdSe Magic-Size Clusters.

J Phys Chem A

April 2020

Center for Interdisciplinary Research, Tohoku University, Aramaki-Aza Aoba 6-3, Sendai 980-8578, Japan.

Experimental and computational studies of resonant Raman spectra of truly monosized (CdSe) and (CdSe) nanoclusters have been performed. First-principles calculations of vibrations are performed to account for the peculiarity of the spectrum and resonant Raman selection rules. The calculation method is based on the analysis of the spatial distribution of the electron density in the ground and excited states and the corresponding displacement of atoms after the electronic transition.

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A special electronic tongue system based on photoelectric measurements on Si-Si/SiN sensitive structures is reported. The sensing approach is based on measuring of minority carrier lifetime in silicon-based substrates using microwave-detected photoconductance decay. This inexpensive and environmentally friendly combinatorial electronic sensing platform is able to create characteristic electronic fingerprints of liquids, detect, and recognize them.

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An open-source drug discovery platform enables ultra-large virtual screens.

Nature

April 2020

Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Harvard University, Boston, MA, USA.

On average, an approved drug currently costs US$2-3 billion and takes more than 10 years to develop. In part, this is due to expensive and time-consuming wet-laboratory experiments, poor initial hit compounds and the high attrition rates in the (pre-)clinical phases. Structure-based virtual screening has the potential to mitigate these problems.

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The title compound represents the thallium(I) salt of a substituted 1,2,5-oxa-diazole, [Tl(CHNO)] , with amino- and hydroxamate groups in the 4- and 3- positions of the oxa-diazole ring, respectively. In the crystal, the deprotonated hydroxamate group represents an inter-mediate between the keto/enol tautomers and forms a five-membered chelate ring with the thallium(I) cation. The coordination sphere of the cation is augmented to a distorted disphenoid by two monodentately binding O atoms from two adjacent anions, leading to the formation of zigzag chains extending parallel to the axis.

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Virtual discovery of melatonin receptor ligands to modulate circadian rhythms.

Nature

March 2020

Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo (SUNY), The State University of New York, Buffalo, NY, USA.

The neuromodulator melatonin synchronizes circadian rhythms and related physiological functions through the actions of two G-protein-coupled receptors: MT and MT. Circadian release of melatonin at night from the pineal gland activates melatonin receptors in the suprachiasmatic nucleus of the hypothalamus, synchronizing the physiology and behaviour of animals to the light-dark cycle. The two receptors are established drug targets for aligning circadian phase to this cycle in disorders of sleep and depression.

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