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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maksimov, Dmitrii N., Tanner, Gregor
Заглавие : A hybrid approach for predicting the distribution of vibro-acoustic energy in complex built-up structures
Место публикации : J. Acoust. Soc. Am. - 2011. - Vol. 130, Is. 3. - С. 1337-1347. - ISSN 0001-4966, DOI 10.1121/1.3621321. - ISSN 1520-8524
Примечания : Cited Reference Count: 31. - European CommunityEuropean Commission [PIAP-GA-2008-230597]; EPSRCUK Research & Innovation (UKRI)Engineering & Physical Sciences Research Council (EPSRC) [EP/F069189/1] Funding Source: UKRI; Engineering and Physical Sciences Research CouncilUK Research & Innovation (UKRI)Engineering & Physical Sciences Research Council (EPSRC) [EP/F069189/1] Funding Source: researchfish, We thank David Chappell and Niels Sondergaard for stimulating discussions and reading the manuscript. Fruitful discussions with Brian Mace, Frank Vogel, and Cathleen Seidel are acknowledged. We have received financial support through the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant No. PIAP-GA-2008-230597.
Предметные рубрики: Acoustics
Audiology & Speech-Language Pathology
Аннотация: Finding the distribution of vibro-acoustic energy in complex built-up structures in the mid-to-high frequency regime is a difficult task. In particular, structures with large variation of local wavelengths and/or characteristic scales pose a challenge referred to as the mid-frequency problem. Standard numerical methods such as the finite element method (FEM) scale with the local wavelength and quickly become too large even for modern computer architectures. High frequency techniques, such as statistical energy analysis (SEA), often miss important information such as dominant resonance behavior due to stiff or small scale parts of the structure. Hybrid methods circumvent this problem by coupling FEM/BEM and SEA models in a given built-up structure. In the approach adopted here, the whole system is split into a number of subsystems that are treated by either FEM or SEA depending on the local wavelength. Subsystems with relative long wavelengths are modeled using FEM. Making a diffuse field assumption for the wave fields in the short wave length components, the coupling between subsystems can be reduced to a weighted random field correlation function. The approach presented results in an SEA-like set of linear equations that can be solved for the mean energies in the short wavelength subsystems. (C) 2011 Acoustical Society of America. [DOI: 10.1121/1.3621321]
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu H., Liao L., Molokeev M. S., Guo Q., Zhang Y., Mei L.
Заглавие : A novel single-phase white light emitting phosphor Ca9La(PO4)5(SiO4)F2:Dy3+: Synthesis, crystal structure and luminescence properties
Место публикации : RSC Adv.: Royal Society of Chemistry, 2016. - Vol. 6, Is. 29. - P.24577-24583. - ISSN 20462069 (ISSN), DOI 10.1039/c5ra23348h
Примечания : Cited References: 33. - We gratefully acknowledge the financial support by the National Natural Science Foundations of China (Grant no. 41172053), the Fundamental Research Funds for the Central Universities (Grant no. 2652013043), and Science and Technology Innovation Fund of the China University of Geosciences (Beijing).
Предметные рубрики: Energy-transfer
Diodes
LEDs
Emission
Ions
Excitation
Ce3+
Eu2+
Ln
Аннотация: A novel single-phase white light emitting phosphor Ca9La(PO4)5(SiO4)F2:Dy3+ was prepared through traditional high-temperature solid state technology. The crystal structures of Ca9La(PO4)5(SiO4)F2 with or without Dy3+ ions were refined by the Rietveld method. The diffuse reflection spectra, excitation spectra, emission spectra, and decay times were characterized to investigate the photoluminescence properties for application in white light-emitting diodes. The results showed that the Ca9La(PO4)5(SiO4)F2:Dy3+ phosphor could efficiently assimilate n-UV light and emit blue (∼485 nm) and yellow light (∼580 nm), originating from the f-f transitions of Dy3+. The critical Dy3+ quenching concentration (QC) was determined to be about 15 mol%, and the corresponding QC mechanism was verified to be the dipole-dipole interaction. Additionally, the emission colors of all samples were located close to the ideal white light region, and the optimal chromaticity coordinates and correlated color temperature (CCT) were determined to be (x = 0.338, y = 0.336) and 5262 K. All the above results indicate that the as-prepared Ca9La(PO4)5(SiO4)F2:Dy3+ phosphor could serve as a promising candidate for white-light n-UV-LEDs. © The Royal Society of Chemistry 2016.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fransson J., Sandalov I., Eriksson O.
Заглавие : A perfect spin-filter quantum dot system
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2004. - Vol. 16, Is. 16. - P.L249-L254. - ISSN 0953-8984, DOI 10.1088/0953-8984/16/16/L03
Примечания : Cited References: 39
Предметные рубрики: NARROW ENERGY BANDS
ELECTRON CORRELATIONS
MAGNETIC-FIELD
MAGNETOTRANSPORT
CONDUCTANCE
RESISTANCE
BARRIER
FORMULA
VALVE
LIMIT
Ключевые слова (''Своб.индексиров.''): electric potential--electron tunneling--magnetic couplings--magnetic fields--magnetic filters--transport properties--electron correlations--magnetic contacts--source-drain voltage--spin projections--semiconductor quantum dots
Аннотация: The discovery of a novel effect in the transport through a QD spin-dependently coupled to magnetic contacts is reported. For a finite range of source-drain voltages the spin projections of the current cancel exactly, resulting in a completely suppressed output current. The spin down current behaves as one normally expects whereas the spin up current becomes negative. As the source-drain voltage is increased the spin up current eventually becomes positive. Thus, tuning the source-drain voltage such that the spin up current vanishes will result in a perfect spin filter.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gluck M., Kolovsky A. R., Korsch H. J.
Заглавие : A quantum cable car for Wannier-Stark ladders
Место публикации : Phys. Lett. A. - 2000. - Vol. 276, Is. 1-4. - P.167-174. - ISSN 0375-9601, DOI 10.1016/S0375-9601(00)00656-3
Примечания : Cited References: 13
Предметные рубрики: DYNAMIC LOCALIZATION
BLOCH PARTICLE
AC FIELDS
DC
STATES
STATISTICS
LIFETIME
Ключевые слова (''Своб.индексиров.''): wannier-stark ladder--induced transitions--induced transitions--wannier-stark ladder--article--energy--oscillation--quantum mechanics--time--transport kinetics
Аннотация: This Letter studies the dynamics of transitions between the levels of a Wannier-Stark ladder induced by a resonant periodic driving. The analysis of the problem is done in terms of resonance quasienergy states, which take into account the metastable character of the Wannier-Stark states. It is shown that the periodic driving creates from a localized Wannier-Stark state an extended Bloch-like state with a spatial length varying in time as similar to t(1/2). Such a state can find applications in the field of atomic optics because it generates a coherent pulsed atomic beam. (C) 2000 Elsevier Science B.V. All rights reserved.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Sorokin P. B., Kuzubov A. A.
Заглавие : Ab initio study of hydrogen chemical adsorption on platinum surface/carbon nanotube join system
Место публикации : Phys. Status Solidi B. - 2008. - Vol. 245, Is. 8. - P.1546-1551. - ISSN 0370-1972, DOI 10.1002/pssb.200844155
Примечания : Cited References: 31
Предметные рубрики: WALLED CARBON NANOTUBES
MOLECULAR-DYNAMICS
ROOM-TEMPERATURE
STORAGE
ENERGY
THERMODYNAMICS
GRAPHITE
DENSITY
POINTS
Аннотация: The process of hydrogen chemical adsorption on platinum cluster/single wall carbon nanotube (CNT) join surfaces is modelled at various temperatures and pressures. For that, the adsorption energy of hydrogen atoms on surfaces of both platinum (111) plate and CNT (5,5) or (8,8) types is calculated by density functional theory with the PBE approximation. At various temperatures the hydrogen atom hopping rate on both platinum and CNT surfaces is calculated by the transition state theory. Furthermore the hydrogen hopping rate from the platinum surface to the attached nanotube is obtained by calculation of the total energy profile. It is proved that hydrogen atoms can migrate easily at the platinum surface at all temperatures, but at the CNT surface they can migrate beginning at 400-500 K. By calculation of chemical potentials of hydrogen in gas or on CNT or platinum cluster surfaces the equilibrium density of adsorbed hydrogen was calculated at different temperatures and pressures. It is established that for all temperatures in the range 300-900 K and for all pressures less than 500 bar, the hydrogen is dissociated and chemically adsorbed on the platinum surface very effectively, but surface site occupation by hydrogen on attached CNT surface is rather small. But if CNT vacancies are present in the tube structure and the temperature is lower then 450 K, hydrogen atoms can be adsorbed effectively enough on these vacancies. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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6.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Fedorov A. S., Churilov G. N., Kuzubov A.A., Serjantova M.V.
Заглавие : Ab-initio investigation of hydrogen absorption by magnesium nanoparticles
Коллективы : "Carbon Nanomaterials in Clean-Energy Hydrogen Systems", national conference
Место публикации : Carbon Nanomaterials in Clean-Energy Hydrogen Systems: Proceedings of the NATO Advanced Research Workshop on Using Carbon Nanomaterials in Clean-Energy Hydrogen Systems Sudak, Crimea, Ukraine 22–28 September 2007/ red. Baranowski, B.; Zaginaichenko, S.; Schur, D.; Skorokhod, V.; Veziroglu, A.: Springer, 2008. - С. 603-610. - (SNATO Science for Peace and Security Series Subseries: NATO Science for Peace and Security Series C: Environmental Security). - ISBN 1874-6519, DOI 10.1007/978-1-4020-8898-8_75
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Sadreev A. F.
Заглавие : Ab-initio investigation of thermoactivated directional transport of hydrogen molecules inside narrow carbon nanotubes
Место публикации : Phys. Status Solidi B. - 2009. - Vol. 246: 23rd Winterschool on Electronic Properties of Novel Materials (MAR 14, 2009, Kirchberg, GERMANY), Is. 11. - P.2598-2601. - ISSN 0370-1972, DOI 10.1002/pssb.200982285
Примечания : Cited References: 21. - A.S.Fedorov thanks the Institute of Computer Modeling (Krasnoyarsk, Russia) and the Joint Supercomputer Center (Moscow) for an assistence in quantum chemical calculations.
Предметные рубрики: DIFFUSION
ENERGY
Аннотация: Using the pseudopotential DFT and the empirical potential methods we calculate the potential acting to the hydrogen molecules in narrow single-wall carbon nanotubes (SWCNT) (6,0),(7,0) and (3,3). The potential forms a goffered potential surface and can be approximated as V(z, r, phi) approximate to V(0) sin(2 pi z/a) + V(r). We show that in these SWCNTs transport of molecules is given mainly by thermoactivated hoppings between minima of the periodic potential along the tube axis. Taking into account that hydrogen density distribution inside nanotube is stationary and assuming the temperature is changed linearly along the SWCNT length we show that the H(2) density is sufficiently variated, especially for the case of (6,0)SWCNT where the density on both SWCNT ends are different at similar to 30 times when the temperature is changed along the SWCNT from 300K to 1200K. Suppose that H2 molecules can penetrate in the both open SWCNT ends, the molecules would move in the direction of the temperature decreasing. This effect may be used potentially to build up a molecular pump driven by the temperature gradient along narrow nanotube. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanova N. B., Kazak N. V., Markov V. V., Ovchinnikov S. G., Rudenko V. V., Abd-Elmeguid M. M.
Заглавие : Analysis of the electrical and optical properties of VBO3 single crystals and Fe1-xVxBO3 solid solutions on the basis of a many-electron model of energy band structure
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 8. - P1462-1468. - ISSN 1063-7834, DOI 10.1134/1.1788779
Примечания : Cited References: 32. - One of the authors (M.M.A.) would like to thank the Deutsche Forschungsgemeinschaft (SFB608) for financial support. This study was supported by the Russian Foundation for Basic Research (project no. 03-02-16286), the program "Integration" (project no. B0017), and the program of the Division of Physical Sciences of the Russian Academy of Sciences "Strongly Correlated Electrons"
Предметные рубрики: MAGNETIC-PROPERTIES
CALCITE STRUCTURE
PHASE-TRANSITION
FERRIC BORATE
HIGH-PRESSURE
FEBO3
FE1-XCRXBO3
FERROMAGNET
MOSSBAUER
SPECTRA
Аннотация: A many-electron model of the energy band structure of VBO3 and of Fe1 - xVxBO3 solid solutions is proposed with strong electron correlations taken into account. Experimental optical absorption spectra and data on the resistivity are discussed in the framework of the suggested model. Variation in the magnetic and electronic properties of VBO3 and Fe1 - xVxBO3 under high pressure is predicted. For VBO3, a Mott-Hubbard (insulator-metal) transition is expected in the high-pressure phase. In Fe1 - xVxBO3 solid solutions, a nontrivial variation in the properties is predicted, leading to the appearance of a different magnetic state. (C) 2004 MAIK "Nauka / Interperiodica".
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov D.G., Kitaura K., Avramov P. V., Jensen J.H.
Заглавие : Analytic gradient for the adaptive frozen orbital bond detachment in the fragment molecular orbital method
Место публикации : Chem. Phys. Lett. - 2009. - Vol. 477, Is. 1-3. - P.169-175. - JUL 28. - ISSN 0009-2614, DOI 10.1016/j.cplett.2009.06.072
Примечания : Cited Reference Count: 49. - Гранты: We thank Professor M. Suenaga of Kyushu University for continuing his development of the modeling software FACIO and its FMO interface. D. G. F. and K. K. were supported by the a Grant-in- Aid for Scientific Research (JSPS, Japan) and the Next Generation SuperComputing Project, Nanoscience Program (MEXT, Japan). J.H.J. was supported by a Skou Fellowship from the Danish Research Agency (Forskningsradet for Natur og Univers).Финансирующая организация: JSPS, Japan; Next Generation SuperComputing Project; MEXT, Japan; Danish Research Agency
Предметные рубрики: DENSITY-FUNCTIONAL THEORY
GEOMETRY OPTIMIZATIONS
SEMICONDUCTOR NANOWIRES
SILICON NANOWIRES
METHOD FMO
ENERGY
SURFACES
RECONSTRUCTION
CHEMISTRY
PROTEINS
Ключевые слова (''Своб.индексиров.''): energy gradients--fragment molecular orbital methods--future applications--geometry optimization--numerical criteria--silicon nanowires--molecular modeling--molecular orbitals
Аннотация: We have developed and implemented the analytic energy gradient for the bond detachment scheme in the fragment molecular orbital method (FMO) suitable to describe solids, and applied it to the geometry optimization of a silicon nanowire at several levels of theory. In addition, we have examined in detail the effects of the particular choice of the fragmentation upon the accuracy and introduced a number of numerical criteria to characterize the errors. The established route is expected to provide guidance for future applications of FMO to surfaces, solids and nanosystems. (C) 2009 Elsevier B. V. All rights reserved.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Arauzo A., Bartolome J., Molokeev M. S., Dudnikov V. A., Solovyov L., Borus A., Ovchinnikov S. G.
Заглавие : Anisotropic thermal expansion and electronic transitions in the Co3BO5 ludwigite
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2022. - Vol. 51, Is. 16. - С. 6345-6357. - ISSN 14779226 (ISSN), DOI 10.1039/d2dt00270a
Примечания : Cited References: 57. - We are grateful to the Russian Foundation for Basic Research (project no. 20-02-00559 and 21-52-12033) for supporting this paper. This work was performed within the framework of the budget project no. 0287-2021-0013 for the Institute of Chemistry and Chemical Technology SB RAS. We acknowledge the financial support from the Spanish Ministry of Economy, Industry and Competitiviness (MINECO), (Grant No. MAT2017-83468-R) and from the regional Government of Aragón (E12-20R RASMIA project)
Аннотация: The investigations of the crystal structure, magnetic and electronic properties of Co3BO5 at high temperatures were carried out using powder X-ray diffraction, magnetic susceptibility, electrical resistivity, and thermopower measurements. The orthorhombic symmetry (Sp.gr. Pbam) was observed at 300 K and no evidence of structural phase transitions was found up to 1000 K. The compound shows a strong anisotropy of the thermal expansion. A large negative thermal expansion along the a-axis is observed over a wide temperature range (T = 300–600 K) with αa = −35 M K−1 at T = 500 K with simultaneous expansion along the b- and c-axes with αb = 70 M K−1 and αc = 110 M K−1, respectively. The mechanisms of thermal expansion are explored by structural analysis. The activation energy of the conductivity decreases significantly above 700 K. Electronic transport was found to be a dominant conduction mechanism in the entire temperature range. The correlations between the thermal expansion, electrical resistivity, and effective magnetic moment were revealed and attributed to the evolution of the spin state of Co3+ ions towards the spin crossover and gradual charge-ordering transition.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kagan M. Y., Mitskan V. A., Korovushkin M. M.
Заглавие : Anomalous superconductivity and superfluidity in repulsive fermion systems
Место публикации : Phys. Usp.: Turpion, 2015. - Vol. 58, Is. 8. - P.733-761. - ISSN 10637869 (ISSN), DOI 10.3367/UFNe.0185.201508a.0785
Примечания : Cited References: 369. - We are grateful to M A Baranov, A V Chubukov, D V Efremov, M V Feigel'man, V V Kabanov, K I Kugel', M S Marienko, N M Plakida, N V Prokorev, A Ya Tzalenchuk, and V V Val'kov for the fruitful discussions and constant attention to our work. The work was supported by the Russian Foundation for Basic Research (project nos. 14-02-00058 and 14-02-31237). M Yu K thanks the Program of Basic Research of the National Research University Higher School of Economics for support. The work of MM K was supported by grant of the President of the Russian Federation (SP-1361.2015.1) and the Dinasty Foundation
Предметные рубрики: HEXAGONAL BORON-NITRIDE
SCANNING-TUNNELING-MICROSCOPY
2-DIMENSIONAL HUBBARD-MODEL
HIGH-TC SUPERCONDUCTIVITY
ELECTRON-ENERGY SPECTRUM
P-WAVE SUPERCONDUCTIVITY
DOUBLE-LAYER GRAPHENE
2D KONDO-LATTICE
GROUND-STATE
TRANSITION-TEMPERATURE
Ключевые слова (''Своб.индексиров.''): anomalous superconductivity--kohn-luttinger mechanism--superfluidity--repulsive fermi gas--hubbard and t-jmodel--shubin vonsovsky model--graphene monolayer--graphene bilayer
Аннотация: We discuss the mechanisms of unconventional superconductivity and superfluidity in 3D and 2D fermionic systems with purely repulsive interaction at low densities. We construct phase diagrams of these systems and find the areas of the superconducting state in free space, as well as on the lattice in the framework of the Fermi-gas model with hard-core repulsion, the Hubbard model, the Shubin-Vonsovsky model, and the t-J model. We demonstrate that the critical superconducting temperature can be greatly increased in the spin-polarized case or in a two-band situation already at low densities. The proposed theory is based on the Kohn-Luttinger mechanism or its generalizations and explains or predicts anomalous p-, d-, and f-wave pairing in various materials, such as high-temperature superconductors, the idealized monolayer and bilayer of doped graphene, heavy-fermion systems, layered organic superconductors, superfluid 3He, spin-polarized 3He mixtures in 4He, ultracold quantum gases in magnetic traps, and optical lattices.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sorokin P. B., Ovchinnikov S. G., Avramov P. V., Chernozatonskii L.A., Fedorov D.G.
Заглавие : Atypical quantum confinement effect in silicon nanowires
Место публикации : J. Phys. Chem. A. - WASHINGTON: AMER CHEMICAL SOC, 2008. - Vol. 112, Is. 40. - С. 9955-9964. - OCT 9. - ISSN 1089-5639, DOI 10.1021/jp805069b
Примечания : Cited Reference Count: 25. - Гранты: This work was in part partially supported by a CREST (Core Research for Evolutional Science and Technology) grant in the Area of High Performance Computing for Multiscale and Multiphysics Phenomena from the Japan Science and Technology Agency (JST) as well as by Russian Fund of Basic Researches (grant 08-02-01096) (L.A.C.). P.V.A. acknowledges the encouragement of Dr. Keiji Morokuma, Research Leader at Fukui Institute for Fundamental Chemistry. The geometry of all presented structures was visualized by ChemCraft software.SUP25/SUP L.A.C. acknowledges I. V. Stankevich for help and fruitful discussions. P.B.S. is grateful to the Joint Supercomputer Center of the Russian Academy of Sciences for access to a cluster computer for quantum-chemical calculations.Финансирующая организация: Japan Science and Technology Agency (JST); Russian Fund of Basic Researches [08-02-01096]
Предметные рубрики: ELECTRONIC-STRUCTURE
OPTICAL-PROPERTIES
SI
DENSITY
WIRES
EXCHANGE
ATOMS
DOTS
Ключевые слова (''Своб.индексиров.''): electric wire--energy gap--gallium alloys--mathematical models--nanostructured materials--nanostructures--nanowires--quantum confinement--quantum electronics--semiconductor quantum dots--silicon--ami methods--band gaps--blue shifts--dinger equations--linear junctions--monotonic decreases--quantum confinement effects--quantum dots--semiempirical--silicon nanowires--system sizes--theoretical models--nanocrystalline silicon--nanowire--quantum dot--silicon--article--chemistry--electron--quantum theory--electrons--nanowires--quantum dots--quantum theory--silicon
Аннотация: The quantum confinement effect (QCE) of linear junctions of silicon icosahedral quantum dots (IQD) and pentagonal nanowires (PNW) was studied using DFT and semiempirical AM1 methods. The formation of complex IQD/PNW structures leads to the localization of the HOMO and LUMO on different parts of the system and to a pronounced blue shift of the band gap; the typical QCE with a monotonic decrease of the band gap upon the system size breaks down. A simple one-electron one-dimensional Schrodinger equation model is proposed for the description and explanation of the unconventional quantum confinement behavior of silicon IQD/PNW systems. On the basis of the theoretical models, the experimentally discovered deviations from the typical QCE for nanocrystalline silicon are explained.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rotter I., Sadreev A. F.
Заглавие : Avoided level crossings, diabolic points, and branch points in the complex plane in an open double quantum dot
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2005. - Vol. 71, Is. 3. - Ст.36227. - ISSN 1063-651X, DOI 10.1103/PhysRevE.71.036227
Примечания : Cited References: 49
Предметные рубрики: BERRY TOPOLOGICAL PHASE
EXCEPTIONAL POINTS
GEOMETRIC PHASES
NUCLEAR REACTIONS
RESONANCE STATES
UNIFIED THEORY
S-MATRIX
CONTINUUM
REPULSION
INTERFEROMETER
Ключевые слова (''Своб.индексиров.''): branch points in the complex plane (bpcp)--diabolic points (dp)--geometric phases--riemann sheets--eigenvalues and eigenfunctions--electron energy levels--functions--hamiltonians--quantum theory--resonance--topology--semiconductor quantum dots
Аннотация: We study the spectrum of an open double quantum dot as a function of different system parameters in order to receive information on the geometric phases of branch points in the complex plane (BPCP). We relate them to the geometrical phases of the diabolic points (DPs) of the corresponding closed system. The double dot consists of two single dots and a wire connecting them. The two dots and the wire are represented by only a single state each. The spectroscopic values follow from the eigenvalues and eigenfunctions of the Hamiltonian describing the double dot system. They are real when the system is closed, and complex when the system is opened by attaching leads to it. The discrete states as well as the narrow resonance states avoid crossing. The DPs are points within the avoided level crossing scenario of discrete states. At the BPCP, width bifurcation occurs. Here, different Riemann sheets evolve and the levels do not cross anymore. The BPCP are physically meaningful. The DPs are unfolded into two BPCP with different chirality when the system is opened. The geometric phase that arises by encircling the DP in the real plane, is different from the phase that appears by encircling the BPCP. This is found to be true even for a weakly opened system and the two BPCP into which the DP is unfolded.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Sorokin P. B., Fedorov A. S., Fedorov D. G., Maeda Y.
Заглавие : Band-gap unification of partially Si-substituted single-wall carbon nanotubes
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2006. - Vol. 74, Is. 24. - Ст.245417. - ISSN 1098-0121, DOI 10.1103/PhysRevB.74.245417
Примечания : Cited References: 72
Предметные рубрики: SILICON-CARBIDE NANOTUBES
DENSITY-FUNCTIONAL THEORY
TOTAL-ENERGY CALCULATIONS
WAVE BASIS-SET
ELECTRONIC-STRUCTURE
AB-INITIO
NANORODS
EXCITATIONS
TRANSITION
NANOWIRES
Аннотация: The atomic and electronic structure of a set of pristine single wall SiC nanotubes as well as Si-substituted carbon nanotubes and a SiC sheet was studied by the local-density approximation (LDA) plane wave band structure calculations. Consecutive substitution of carbon atoms by Si leads to a gap opening in the energetic spectrum of the metallic (8,8) SWCNT with approximately quadratic dependence of the band gap upon the Si concentration. The same substitution for the semiconductor (10,0) single wall carbon nanotubes (SWCNT) results in a band gap minimum (0.27 eV) at similar to 25% of Si concentration. In the Si concentration region of 12-18 %, both types of nanotubes have less than 0.5 eV direct band gaps at the Gamma-Gamma point. The calculation of the chiral (8,2) SWSi0.15C0.85NT system gives a similar (0.6 eV) direct band gap. The regular distribution of Si atoms in the atomic lattice is by similar to 0.1 eV/atom energetically preferable in comparison with a random distribution. Time dependent density functional theory (DFT) calculations showed that the silicon substitution sufficiently increases (roughly by one order of magnitude) the total probability of optical transitions in the near infrared region, which is caused by the opening of the direct band gap in metallic SWCNTs, the unification of the nature and energy of the band gaps of all SWCNT species, the large values of Si3p parallel to r parallel to Si3s radial integrals and participation of Si3d states in chemical bonding in both valence and conductance bands.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Cazacu, Nicoleta, Chilom, Claudia G., Iftimie, Sorina, Balasoiu, Maria, Ladygina, Valentina P., Stolyar S. V., Orelovich, Oleg L., Kovalev, Yuriy S., Rogachev, Andrey V.
Заглавие : Biogenic ferrihydrite nanoparticles produced by Klebsiella oxytoca: Characterization, physicochemical properties and bovine serum albumin interactions
Место публикации : Nanomaterials. - 2022. - Vol. 12, Is. 2. - Ст.249. - ISSN 2079-4991(eISSN), DOI 10.3390/nano12020249
Примечания : Cited References: 59. - This research was funded by JINR Themes 02-1-1107-2011/2021, 04-5-1131-2017/2021 and 04-4-1133-2018/2023 and with the financial support of the RO-JINR Projects Nos. 366/11.05.2021 (items 7, 86, 97) and 365/11.05.2021 (items 8, 87 and 98). This work also benefited from the use of the SasView application, originally developed under NSF Award DMR-0520547. SasView also contains the code developed with funding from the EU Horizon 2020 program under the SINE2020 project Grant No 654000. The APC was funded by JINR Theme 02-1-1107-2011/2021, Project No. 366/11.05.2021, item 7. This study used the infrastructure of the Applied Genetics Resource Facility of MIPT (Suport Grant 075-15-2021-684)
Предметные рубрики: MAGNETIC-PROPERTIES
REDUCTION
MOSSBAUER
FERRITIN
DOCKING
BINDING
Аннотация: The synthesis of nanoparticles inside microorganisms is an economical alternative to chemical and physical methods of nanoparticle synthesis. In this study, ferrihydrite nanoparticles synthesized by Klebsiella oxytoca bacterium in special conditions were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), small-angle X-ray (SAXS), UV-Vis spectroscopy, fluorescence, fluorescence resonance energy transfer (FRET), and molecular docking. The morphology and the structure of the particles were characterized by means of SEM and SAXS. The elemental content was determined by means of the EDS method. The absorption properties of the ferrihydrite nanoparticles were investigated by UV-Vis spectroscopy. The binding mechanism of the biogenic ferrihydrite nanoparticles to Bovine Serum Albumin (BSA) protein, studied by fluorescence, showed a static and weak process, combined with FRET. Protein denaturation by temperature and urea in the presence of the ferrihydrite nanoparticles demonstrated their influence on the unfolding process. The AutoDock Vina and UCSF Chimera programs were used to predict the optimal binding site of the ferrihydrite to BSA and to find the location of the hydrophobic cavities in the sub-domain IIA of the BSA structure.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu Q., Dang P., Zhang G., Lian H., Li G., Molokeev M. S., Cheng Z., Lin J.
Заглавие : Broad luminescence tuning in Mn2+-doped Rb2Zn3(P2O7)2 via doping level control based on multiple synergies
Место публикации : CrystEngComm. - 2022. - Vol. 24, Is. 31. - P.5622-5629. - ISSN 14668033 (ISSN), DOI 10.1039/d2ce00719c
Примечания : Cited References: 31. - We acknowledge the financial support from the National Natural Science Foundation of China (NSFC No. 51932009, 51720105015, 51929201, 52072349, and 52172166), Projects for the Science and Technology Development Plan of Jilin Province (20210402046GH), and the Natural Science Foundation of Zhejiang Province (LR22E020004)
Аннотация: Here we constructed a series of novel non-centrosymmetric structure phosphors [Rb2Zn3(P2O7)2:Mn2+] by a high-temperature solid-state reaction. The multiband emission can be designed by Mn2+ preferentially occupying three types of crystallographic sites in Rb2Zn3(P2O7)2:Mn2+. The emission color could be continuously tuned from yellow-green to orange-red via multiple synergies among crystallographic site engineering, energy transfer, and Mn-Mn dimmers alone through the dopant concentration. These color-tunable phosphors have good thermal stability (I150 °C/I25 °C = 91%). The as-prepared pc-WLED has a low corresponding color temperature (CCT = 4820 K) and a high color rendering index (Ra = 90.4) with CIE color coordinates of (0.351, 0.358). These results show that emission-tunable Rb2Zn3(P2O7)2:xMn2+ phosphors are potential candidates for application in n-UV-based pc-WLED devices. This study offers a new insight for wide-range tuning of PL properties by using crystallographic site engineering through changing the doping level in Mn-activated phosphors.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Deng, Chenkai, Hao, Shiqiang, Liu, Kunjie, Molokeev M. S., Wolverton, Christopher, Fan, Liubing, Zhou, Guojun, Chen, D.a., Zhao, Jing, Liu, Quanlin
Заглавие : Broadband light emitting zero-dimensional antimony and bismuth-based hybrid halides with diverse structures
Коллективы : Beijing Municipal Natural Science FoundationBeijing Natural Science Foundation [2182080]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [51972021, 51702329]; Fundamental Research Funds for the Central UniversitiesFundamental Research Funds for the Central Universities [FRF-IDRY-19-005]; RFBRRussian Foundation for Basic Research (RFBR) [19-52-80003]; Department of Energy, Office of Science Basic Energy SciencesUnited States Department of Energy (DOE) [DE-SC0014520]
Место публикации : J. Mater. Chem. C. - 2021. - Vol. 9, Is. 44. - P.15942-15948. - ISSN 2050-7526, DOI 10.1039/d1tc04198c. - ISSN 2050-7534(eISSN)
Примечания : Cited References: 52. - This work was supported by Beijing Municipal Natural Science Foundation (2182080) and the National Natural Science Foundation of China (51972021 and 51702329). The work was partly supported by the Fundamental Research Funds for the Central Universities (FRF-IDRY-19-005) and by the RFBR according to the research project No. 19-52-80003. S. H. and C. W. (DFT calculations) acknowledge support from the Department of Energy, Office of Science Basic Energy Sciences under Grant DE-SC0014520. Access to QUEST, the supercomputing resources facilities at Northwestern University, is also acknowledged
Предметные рубрики: CRYSTAL-STRUCTURE
LONE-PAIR
EMISSION
PEROVSKITES
TIN
LUMINESCENCE
Аннотация: Low-dimensional organic–inorganic metal halides have recently attracted extensive attention because of their various structures and distinguished photoelectric properties. Herein, we report a series of new zero-dimensional organic–inorganic hybrid metal halides: (TMEDA)3Bi2Cl12·H2O, (TMEDA)3Bi2Br12·H2O, (TMEDA)3Sb2Br12·H2O, and (TMEDA)5Sb6Cl28·2H2O [TMEDA = N,N,N′·trimethylethylenediamine]. (TMEDA)3M2X12·H2O (M = Bi or Sb, X = Cl or Br) crystallizes in the monoclinic space group P21/n, and (TMEDA)5Sb6Cl28·2H2O crystallizes in the orthorhombic space group Pnma. (TMEDA)3M2X12 possesses a zero-dimensional structure with the metal halide ions of [MBr6]3− isolated by the organic TMEDA2+ cations. Interestingly, the (TMEDA)5Sb6Cl28·2H2O structure consists of a combination of corner-connected octahedra [Sb4Cl18]6− and edge-shared [Sb2Cl10]4−, which is quite rare. The light emission of all these compounds was measured, and (TMEDA)3Sb2Br12·H2O exhibits the most intense luminescence. Upon 400 nm ultraviolet light excitation, (TMEDA)3Sb2Br12·H2O exhibited strong broadband yellow emission centered at 625 nm with a full-width at half-maximum of ∼150 nm originating from self-trapped excitons. This work suggests the possibility of new types of hybrid halides by introducing different metal centers and probing the structural evolution and photoluminescent properties, serving as a reference for the relationship between structure and luminescent performance and demonstrating their potential use as phosphors in light-emitting diodes.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Drokin N. A., Kiiko V. S., Pavlov A. V., Malkin A. I.
Заглавие : BT-30 Ceramic Electrophysical Properties
Место публикации : Refract. Ind. Ceram. - 2020. - Vol. 61, Is. 3. - P.341-348. - ISSN 1083-4877 (ISSN), DOI 10.1007/s11148-020-00484-2. - ISSN 1573-9139 (eISSN)
Примечания : Cited References: 12
Аннотация: A total complex resistance (impedance) method is used to study the electrophysical characteristics of (BeO + TiO2)-ceramics modified with TiO2 micro- and nanoparticles in an amount of 30 wt.% (BT-30). Dispersion of the actual ε′ and imaginary ε′′ components of the dielectric permittivity component and specific conductivity in the frequency range from 100 Hz to 100 MHz from room temperature to the boiling point of liquid nitrogen are determined. High values of ε′ and ε′′ in the low-frequency range are typical for structurally inhomogeneous materials due to the accumulation of electric charges at the surface and within microcrystals. Two dielectric relaxation processes associated with electrical conductivity within the body and at the surface of ceramics are detected for the first time. An increase in conductivity with an increase in the microwave field frequency above 1 MHz is explained by the appearance of a current relaxation component. The activation energy of the static resistance of ceramic specimens is determined as a function of the reciprocal temperature that depends little on the weight content of TiO2 nanoparticles and varies in the range of 0.024 – 0.10 eV This also confirms the existence of two independent conduction processes, weakly dependent on the nanoparticle content in the ceramic composition. With placement of ceramic in a high-frequency electric field, spatial charges are formed, the field of which contributes to creation of additional polarization and dielectric losses.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Kovaleva E. A., Avramov P. V., Kholtobina A. S., Mikhaleva N. S., Kuklin A. V.
Заглавие : Buckminsterfullerene's movability on the Fe(001) surface
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 410. - P.41-46. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2016.03.023
Примечания : Cited References: 32. - This work was supported by the Russian Scientific Fund (Project no. 14-13-00139) and the Foundation for Assistance to Small Innovative Enterprises (FASIE) (Project no. 0011742). The authors would like to thank Institute of Computational Modeling of SB RAS, Krasnoyarsk; Joint Supercomputer Center of RAS, Moscow; Center of Equipment for Joint Use of Siberian Federal University, Krasnoyarsk; ICC of Novosibirsk State University and Siberian Supercomputer Center (SSCC) of SB RAS, Novosibirsk for providing the access to their supercomputers.
Предметные рубрики: Initio molecular-dynamics
Total-energy calculations
Augmented-wave
Ключевые слова (''Своб.индексиров.''): buckminsterfullerene--c60--fe(001)--spintronics--adsorption--relocation--dft
Аннотация: Organic-based spintronics is one of the most fast-developing fields in nanoelectronics. Buckminsterfullerene-based composites are widely investigated due to its unique properties and there is a number of studies concerned with its interfaces with various types of substrates. Ferromagnetic surfaces are of a particular interest for potential spintronics applications. Based on the data reported in literature, we suppose that there are more than one stable structure in C60/Fe(001) composite system. Here we investigate different possible adsorption sites of C60 molecule and reveal the possibility of their coexistence and its influence on the composite properties. © 2016 Elsevier B.V.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Guan, Ming, Zheng, Hong, Huang, Zhaohui, Ma, Bin, Molokeev M. S., Huang, Saifang, Mei, Lefu
Заглавие : Ca/Sr ratio dependent structure and up-conversion luminescence of (Ca1-xSrx)In2O4 : Yb3+/Ho3+ phosphors
Место публикации : RSC Adv.: Royal Society of Chemistry, 2015. - Vol. 5, Is. 73. - P.59403-59407. - ISSN 2046-2069, DOI 10.1039/c5ra08467a
Примечания : Cited References:25. - This present work was supported by the National Natural Science Foundations of China (Grant no. 51202226), the Fundamental Research Funds for the Central Universities (Grant no. 2652014125, 2652013128, 2652013043), and the Research Fund for the Doctoral Program of Higher Education of China (Grant no. 20130022110006).
Предметные рубрики: CO-DOPED CAIN2O4
ENERGY-TRANSFER
PHOTOLUMINESCENCE
EMISSION
SRIN2O4
Аннотация: Up-conversion (UC) phosphors of (Ca1-xSrx)In2O4 : Yb3+/Ho3+ (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) were prepared. Based on the crystal structure evolution of these series solid solution samples, which were characterized by Rietveld refinement, the variation of UC luminescent properties was discussed in detail. Sr and Ca occupied one position and Yb/Ho dissolved in the In ion site in the (Ca1-xSrx)In2O4 lattice. With increasing Sr substituting Ca atoms, the cell parameters and cell volumes of these samples increased linearly, and distortions of (Ca/Sr)O-8 polyhedron were formed. The distortions on crystal structures showed a negative relation with UC luminescent intensities in these series phosphors.
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