Библиотека института физики им. Л.В. Киренского СО РАН

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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Khalyapin D. L., Maltsev V. K., Kim P. D., Turpanov I. A., Betenkova A. Ya.
Заглавие : The study of Co/Cu multilayers by NMR method
Коллективы : "Trends in Nanomechanics and Nanoengineering", workshop, Сибирский федеральный университет, Институт физики им. Л.В. Киренского Сибирского отделения РАН
Место публикации : Workshop "Trends in Nanomechanics and Nanoengineering" : book of abstracts/ предс. сем. K. S. Aleksandrov ; зам. предс. сем.: G. S. Patrin, S. G. Ovchinnikov ; чл. лок. ком.: N. N. Kosyrev, A. S. Fedorov [et al]. - 2009. - P.27
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Morozov E. V., Yushmanov, Pavel, V, Martyanov, Oleg N.
Заглавие : Temperature-Triggered Rearrangement of Asphaltene Aggregates as Revealed by Pulsed-Field Gradient NMR
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [15-19-00119]
Место публикации : Energy Fuels. - 2019. - Vol. 33, Is. 8. - P.6934-6945. - ISSN 0887-0624, DOI 10.1021/acs.energyfuels.9b00600. - ISSN 1520-5029(eISSN)
Примечания : Cited References: 119. - This research was performed using the equipment of Krasnoyarsk Regional Research Equipment Centre of Siberian Branch of Russian Academy of Sciences with the financial support of Russian Science Foundation (Project No. 15-19-00119).
Предметные рубрики: CRITICAL NANOAGGREGATE CONCENTRATION
ELECTRON-SPIN-RESONANCE
Аннотация: The tendency of asphaltenes for aggregation followed by precipitation and deposition plays a crucial role in the petroleum industry since these processes present severe problems during the production, recovery, and processing of crude oils and fossil hydrocarbon feedstocks. The dynamics of oil asphaltene aggregates dissolved in chloroform at different concentrations varied in a wide range that was investigated at temperatures from 0 to 55 °C using the Pulsed-Field Gradient NMR technique. The components attributed to nanoaggregates and macroaggregates were successfully resolved, which allowed us to measure their diffusion coefficients. The diffusion coefficients for all types of aggregates grow as the asphaltene concentration decreases, whereas the partial weight of the aggregates increases with the increase of asphaltene concentration. The difference in diffusion behavior of the aggregates of different types was registered when passing the critical concentration range 10–20 g/L. The nano- and macroaggregates behave independently when the asphaltene concentration is higher than 20 g/L (concentrated regime), while below 20 g/L (semidiluted regime) the components related to the different types of aggregates cannot be properly resolved. It was found that regardless of the asphaltene concentration, the diffusion coefficients for nano- and macroaggregates demonstrate similar temperature behavior giving the straight lines in the Arrhenius coordinates which change their slopes when passing the temperature range 20–30 °C. The phenomenon evidences the thermally induced cleavage of noncovalent bonds with subsequent rearrangement of asphaltene aggregates that is observed for all concentration regimes covering the existence of asphaltene aggregates of all types. The data obtained are well consistent with the modern concept of asphaltene aggregate structure and fairly agree with the data obtained earlier. We believe these results will contribute essentially to a better understanding of the fundamental behavior of asphaltenes and their aggregates, providing a deep insight into aggregate transformation triggered by the temperature.
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Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Smolyarov K. T., Matsulev A.N., Kondrasenko A. A.
Заглавие : Investigation of Re-Pt vinylidene complexCp(CO)2RePt(μ-C=CHPh)(PPh3)2 by solid-state NMR
Коллективы : Magnetic Resonance and its Applications, International School-Conference, Санкт-Петербургский государственный университет
Место публикации : Magnetic Resonance and its Applications: Proceedings 16th International School-Conference. - 2019. - С. 268-270 (Шифр 39228743)
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Smolyarov K. T., Volkov N. V., Matsulev A. N., Kondrasenko A. A.
Заглавие : The comparative analysis of the solid-state 31P NMR spectra of Re-Pt vinylidene complexes
Коллективы : International Scientific Conference "Conference on Applied Physics, Information Technologies and Engineering"
Место публикации : J. Phys. Conf. Ser. - 2019. - Vol. 1399. - Ст.022028. - ISSN 1742-6588, DOI 10.1088/1742-6596/1399/2/022028. - ISSN 1742-6596 (eISSN)
Примечания : Cited References: 11
Предметные рубрики: Applied Physics
Аннотация: The two vinylidene complexes Cp(CO)2 RePt(μ-C=CHPh)(PPh3 )(CO) and Cp(CO)2 RePt(μ-C=CHPh)(PPh3 )2 and their precursors PPh3 and P(PPh3 )4 were studied by solid-state nuclear magnetic resonance. We analysed 31P cross-polarization spectra acquired in static conditions and with magic angle spinning. The chemical shift tensors of each sample were determined by fitting their spectra using SIMPSON simulations.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vorobyev S. A., Saikova S. V., Erenburg S. B., Trubina S. V., Ivanov Y. N., Maksimov N. G., Mikhlin Y. L.
Заглавие : A comparative study of the structure of copper and lead xanthates
Место публикации : J. Struct. Chem. - 2017. - Vol. 58, Is. 6. - P.1144-1151. - ISSN 00224766 (ISSN), DOI 10.1134/S0022476617060117
Примечания : Cited References: 38
Ключевые слова (''Своб.индексиров.''): copper xanthate--lead xanthate--dixanthogen--structure--xps--exafs--solid state nmr
Аннотация: XPS, PbL3 and CuK EXAFS, solid state NMR, and EPR techniques are used to study insoluble products formed in the interaction of aqueous solutions of lead(II) nitrate and copper (II) sulfate with potassium nbutylxanthate (KX). The XPS spectra of lead xanthates with the composition PbX2 are similar to those of KX, and interatomic distances of 0.279 nm suggest a nearly ionic character of Pb–S bonds. In copper xanthate precipitating together with dixanthogen (approximately 15 wt.%), the Cu(I)–S bond length is smaller (0.229 nm), and copper coordination number of 2.9 in a composite with dixanthogen increases to 3.3 after its removal by washing with acetone. The XPS spectra indicate the covalent character of the bond and non-equivalence of xanthate radicals. Solid state 1H and 13C NMR spectra as well as the actual absence of metal lines under the measurement conditions demonstrate strong disordering of the structure of xanthates, which is stronger for PbX2 and weakest in CuX after the removal of dixanthogen. EPR reveals sulfur-containing radicals and Cu2+ in CuX, however, their amounts are insignificant and decrease after the washing with acetone. The results of the work are significant for the understanding of the reactivity of xanthates, in particular, under the conditions of flotation of base metal ores.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Lundin A. A.
Заглавие : On the effect of an inhomogeneous magnetic field and many-body localization on the increase in the second moment of multiple-quantum NMR with time
Место публикации : JETP Letters. - 2017. - Vol. 105, Is. 8. - P.514-518. - ISSN 00213640 (ISSN), DOI 10.1134/S0021364017080148
Примечания : Cited References: 27
Аннотация: A change in the time dependence of the second moment of the distribution of intensities of coherences with various orders in the spectrum of multiple-quantum NMR in a solid at the inclusion of an inhomogeneous magnetic field in the effective interaction is studied. Both the secular dipole–dipole and nonspecular twoquantum interactions are considered as nucleus–nucleus interactions, which correspond to traditional experimental realizations. It is shown that, with an increase in the magnitude of the inhomogeneous field, an exponential increase in the second moment of multiple-quantum NMR with time changes to a power-law increase. The results obtained in this work indicate that this second moment, which determines the average number of dynamically correlated spins, can be used as a convenient characteristic for studying a transition to a many-body localized state. © 2017, Pleiades Publishing, Inc.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Morozov E. V., Novikov M., Bouznik V., Yurkov G.
Заглавие : NMR imaging of 3D printed biocompatible polymer scaffolds interacting with water
Место публикации : Rapid Prototyping J. - 2019. - Vol. 25, Is. 6. - P.1007-1016. - ISSN 13552546 (ISSN), DOI 10.1108/RPJ-10-2018-0271
Примечания : Cited References: 60. - This research was performed on the equipment of Krasnoyarsk Regional Research Equipment Center of Siberian Branch of Russian Academy of Sciences with the financial support of Russian Foundation for Basic Research (project No14-29-10178 ofi_m).
Аннотация: Purpose: Active employment of additive manufacturing for scaffolds preparation requires the development of advanced methods which can accurately characterize the morphologic structure and its changes during an interaction of the scaffolds with substrate and aqueous medium. This paper aims to use the method of nuclear magnetic resonance (NMR) imaging for preclinical characterization of 3D-printed scaffolds based on novel allyl chitosan biocompatible polymer matrices. Design/methodology/approach: Biocompatible polymer scaffolds were fabricated via stereolithography method. Using NMR imaging the output quality control of the scaffolds was performed. Scaffolds stability, polymer matrix homogeneity, kinetic of swelling processes, water migration pathways within the 3D-printed parts, effect of post-print UV curing on overall scaffolds performance were studied in details. Findings: NMR imaging visualization of water uptake and polymer swelling processes during the interaction of scaffolds with aqueous medium revealed the formation of the fronts within the polymer matrices those dynamics is governed by case I transport (Fickian diffusion) of the water into polymer network. No significant difference was observed in front propagation rates along the polymer layers and across the layers stack. After completing the swelling process, the polymer scaffolds retain their integrity and no internal defects were detected. Research limitations/implications: NMR imaging revealed that post-print UV curing aimed to improve the overall performance of 3D-printed scaffolds might not provide a better quality of the finish product, as this procedure apparently yield strongly inhomogeneous distribution of polymer crosslink density which results in subsequent inhomogeneity of water ingress and swelling processes, accompanied by stress-related cracks formation inside the scaffolds. Practical implications: This study introduces a method which can successfully complement the standard tests which now are widely used in either additive manufacturing or scaffolds engineering. Social implications: This work can help to improve the overall performance of the polymer scaffolds used in tissue engineering. Originality/value: The results of this study demonstrate feasibility of NMR imaging for preclinical characterization of 3D printed biocompatible polymer scaffolds. The results are believed to contribute to better understanding of the processes vital for improving the design of 3D-printed polymer scaffolds. © 2019, Emerald Publishing Limited.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lundin A. A., Zobov V. E.
Заглавие : Asymptotic similarity of time correlation functions and shape of the 13C and 29Si NMR spectra in diamond and silicon
Коллективы : Institute of Chemical Physics of the Russian Academy of Science [0082-2018-0005, TSITIS AAAA-A18-118020690203]
Место публикации : J. Exp. Theor. Phys. - 2018. - Vol. 127, Is. 2. - P.305-315. - ISSN 1063-7761, DOI 10.1134/S1063776118080216. - ISSN 1090-6509(eISSN)
Примечания : Cited References: 47. - We thank V.A. Atsarkin, V.V. Demidov, F.S. Dzheparov, and E. B. Feldman for the discussion of our results. This work was supported by a subsidy allocated by the Institute of Chemical Physics of the Russian Academy of Science for the State assignment, theme 0082-2018-0005, code TSITIS AAAA-A18-118020690203.
Предметные рубрики: SPIN SYSTEMS
LINE-SHAPES
RELAXATION
SOLIDS
PARAMAGNETS
RESONANCE
Аннотация: Based on the proposed theory, we have investigated the shape of the NMR absorption spectra for 13C and 29Si nuclei in diamond and silicon crystals attributable to the internuclear dipole–dipole interaction. In accordance with the available experimental data, we have considered both crystals with a 100% content of magnetoactive isotopes and crystals with a comparatively low dilution by nonmagnetic nuclei. The time correlation functions (the first of which is the Fourier transform of the NMR spectrum) arising in an infinite chain of coupled differential equations are shown to be mutually similar with a slight time delay. The proposed theory allows the spectrum to be calculated analytically. The results obtained agree satisfactorily with the experimental ones. It is noted that the mutual similarity of the time correlation functions is probably a corollary of the development of dynamical chaos in the system.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Lundin A. A.
Заглавие : Effect of degradation processes caused by a small perturbation on the growth of the average cluster size of correlated spins in multiple quantum NMR spectroscopy of solids
Место публикации : Appl. Magn. Reson. - 2021. - Vol. 52. Is. 7. - P.879–892. - ISSN 09379347 (ISSN), DOI 10.1007/s00723-021-01342-1
Примечания : Cited References: 33. - The study is funded by the Ministry of Science and Higher Education of the Russian Federation in the framework of the State assignment, State registration number AAAA-A19-119012890064-7
Аннотация: Multiple quantum (MQ) NMR spectroscopy of solids allows one to observe the growth and decay of multispin correlations. As a rule, the average size of the cluster of correlated spins is extracted from the width of the MQ spectrum. In the present article, the size distribution of such clusters is explored. To obtain the above distribution, the solutions for the amplitudes of the decomposition over complete sets of orthogonal operators for the two different models were used. By means of these models, we have taken into account the dependence of cluster degradation (the degradation of a cluster means, e.g., destruction of correlations in cluster or loss of particles in it) through two positions. The first one defines by the cluster size while the second one depends on the MQ coherence order of the cluster. It is shown that in dependence of the relation the rates of these degradation processes, the width of the MQ spectrum carries different information. If the first process is faster that the second one, then the width of the MQ spectrum is still determined by the average cluster size. When the velocity ratio becomes inverse, the width of the MQ spectrum takes on a smaller value, which is a consequence of the faster degradation of the MQ spectrum components with large orders of coherence.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rakhmatullin A., Molokeev M. S., King G., Polovov I. B., Maksimtsev K. V., Chesneau E., Suard E., Bakirov R., Simko F., Bessada C., Allix M.
Заглавие : Polymorphs of Rb3ScF6: X-ray and Neutron Diffraction, Solid-State NMR, and Density Functional Theory Calculations Study
Место публикации : Inorg. Chem. - 2021. - Vol. 60, Is. 8. - P.6016-6026. - ISSN 00201669 (ISSN), DOI 10.1021/acs.inorgchem.1c00485
Примечания : Cited References: 43. - For DFT calculations, we thank the “Centre de Calcul Scientifique en region Centre” (Orléans, France). We acknowledge the Interface, Confinement, Materials and Nanostructures (Orléans, France) for access to their transmission electron microscope. Financial support from the IR-RMN-THC Fr3050 CNRS for conducting the research is gratefully acknowledged. This study was also financially supported by VEGA-2/0060/18 and ITMS project (code 313021T081, Research & Innovation Operational Programme funded by the ERDF). We thank also Dr. F. Vivet, Dr. F. Fayon, and Dr. D. Massiot for useful discussions
Аннотация: The crystal structures of three polymorphs of Rb3ScF6 have been determined through a combination of synchrotron, laboratory X-ray, and neutron powder diffraction, electron diffraction, and multinuclear high-field solid-state NMR studies. The room temperature (RT; α) and medium-temperature (β) structures are tetragonal, with space groups I41/a (Z = 80) and I4/m (Z = 10) and lattice parameters a = 20.2561(4) Å, c = 36.5160(0) Å and a = 14.4093(2) Å, c = 9.2015(1) Å at RT and 187 °C, respectively. The high-temperature (γ) structure is cubic space group Fm3̅m (Z = 4) with a = 9.1944(1) Å at 250 °C. The temperatures of the phase transitions were measured at 141 and 201 °C. The three α, β, and γ Rb3ScF6 phases are isostructural with the α, β, and δ forms of the potassium cryolite. Detailed structural characterizations were performed by density functional theory as well as NMR. In the case of the β polymorph, the dynamic rotations of the ScF6 octahedra of both Sc crystallographic sites have been detailed.
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