| 1. |
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- 2019
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Journal article (peer-reviewed)
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| 2. |
- Abgrall, N., et al.
(author)
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The large enriched germanium experiment for neutrinoless double beta decay (LEGEND)
- 2017
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In: AIP Conference Proceedings. - : Author(s). - 1551-7616 .- 0094-243X. ; 1894
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Conference paper (peer-reviewed)abstract
- The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated, reveal that neu-trinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of ∼0.1 count /(FWHM·t·yr) in the region of the signal. The current generation 76Ge experiments GERDA and the Majorana Demonstrator, utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale 76Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 1028 years, using existing resources as appropriate to expedite physics results.
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| 3. |
- Litvinov, Dmitry, et al.
(author)
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Probing the gravitational redshift with an Earth-orbiting satellite
- 2018
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In: Physics Letters, Section A: General, Atomic and Solid State Physics. - : Elsevier BV. - 0375-9601. ; 382:33, s. 2192-2198
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Journal article (peer-reviewed)abstract
- We present an approach to testing the gravitational redshift effect using the RadioAstron satellite. The experiment is based on a modification of the Gravity Probe A scheme of nonrelativistic Doppler compensation and benefits from the highly eccentric orbit and ultra-stable atomic hydrogen maser frequency standard of the RadioAstron satellite. Using the presented techniques we expect to reach an accuracy of the gravitational redshift test of order 10−5, a magnitude better than that of Gravity Probe A. Data processing is ongoing, our preliminary results agree with the validity of the Einstein Equivalence Principle.
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| 4. |
- Gusev, A, et al.
(author)
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Atlas of prostate cancer heritability in European and African-American men pinpoints tissue-specific regulation
- 2016
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In: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7, s. 10979-
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Journal article (peer-reviewed)abstract
- Although genome-wide association studies have identified over 100 risk loci that explain ∼33% of familial risk for prostate cancer (PrCa), their functional effects on risk remain largely unknown. Here we use genotype data from 59,089 men of European and African American ancestries combined with cell-type-specific epigenetic data to build a genomic atlas of single-nucleotide polymorphism (SNP) heritability in PrCa. We find significant differences in heritability between variants in prostate-relevant epigenetic marks defined in normal versus tumour tissue as well as between tissue and cell lines. The majority of SNP heritability lies in regions marked by H3k27 acetylation in prostate adenoc7arcinoma cell line (LNCaP) or by DNaseI hypersensitive sites in cancer cell lines. We find a high degree of similarity between European and African American ancestries suggesting a similar genetic architecture from common variation underlying PrCa risk. Our findings showcase the power of integrating functional annotation with genetic data to understand the genetic basis of PrCa.
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| 5. |
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| 6. |
- Litvinov, D. A., et al.
(author)
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RadioAstron gravitational redshift experiment: Status update
- 2018
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In: 14th Marcel Grossman Meeting On Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories, Proceedings. - : WORLD SCIENTIFIC. - 9789813226593 ; , s. 3569-3575
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Conference paper (peer-reviewed)abstract
- A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of 4 × 10−4. We expect to reach 2.5 × 10−5 with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission.
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| 7. |
- Rodriguez, D., et al.
(author)
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MATS and LaSpec : High-precision experiments using ion traps and lasers at FAIR
- 2010
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In: The European physical journal. Special topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 183, s. 1-123
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Research review (peer-reviewed)abstract
- Nuclear ground state properties including mass, charge radii, spins and moments can be determined by applying atomic physics techniques such as Penning-trap based mass spectrometry and laser spectroscopy. The MATS and LaSpec setups at the low-energy beamline at FAIR will allow us to extend the knowledge of these properties further into the region far from stability. The mass and its inherent connection with the nuclear binding energy is a fundamental property of a nuclide, a unique ""fingerprint"". Thus, precise mass values are important for a variety of applications, ranging from nuclear-structure studies like the investigation of shell closures and the onset of deformation, tests of nuclear mass models and mass formulas, to tests of the weak interaction and of the Standard Model. The required relative accuracy ranges from 10(-5) to below 10(-8) for radionuclides, which most often have half-lives well below 1 s. Substantial progress in Penning trap mass spectrometry has made this method a prime choice for precision measurements on rare isotopes. The technique has the potential to provide high accuracy and sensitivity even for very short-lived nuclides. Furthermore, ion traps can be used for precision decay studies and offer advantages over existing methods. With MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly-charged ions) at FAIR we aim to apply several techniques to very short-lived radionuclides: High-accuracy mass measurements, in-trap conversion electron and alpha spectroscopy, and trap-assisted spectroscopy. The experimental setup of MATS is a unique combination of an electron beam ion trap for charge breeding, ion traps for beam preparation, and a high-precision Penning trap system for mass measurements and decay studies. For the mass measurements, MATS offers both a high accuracy and a high sensitivity. A relative mass uncertainty of 10(-9) can be reached by employing highly-charged ions and a non-destructive Fourier-Transform Ion-Cyclotron-Resonance (FT-ICR) detection technique on single stored ions. This accuracy limit is important for fundamental interaction tests, but also allows for the study of the fine structure of the nuclear mass surface with unprecedented accuracy, whenever required. The use of the FT-ICR technique provides true single ion sensitivity. This is essential to access isotopes that are produced with minimum rates which are very often the most interesting ones. Instead of pushing for highest accuracy, the high charge state of the ions can also be used to reduce the storage time of the ions, hence making measurements on even shorter-lived isotopes possible. Decay studies in ion traps will become possible with MATS. Novel spectroscopic tools for in-trap high-resolution conversion-electron and charged-particle spectroscopy from carrier-free sources will be developed, aiming e. g. at the measurements of quadrupole moments and E0 strengths. With the possibility of both high-accuracy mass measurements of the shortest-lived isotopes and decay studies, the high sensitivity and accuracy potential of MATS is ideally suited for the study of very exotic nuclides that will only be produced at the FAIR facility. Laser spectroscopy of radioactive isotopes and isomers is an efficient and model-independent approach for the determination of nuclear ground and isomeric state properties. Hyperfine structures and isotope shifts in electronic transitions exhibit readily accessible information on the nuclear spin, magnetic dipole and electric quadrupole moments as well as root-mean-square charge radii. The dependencies of the hyperfine splitting and isotope shift on the nuclear moments and mean square nuclear charge radii are well known and the theoretical framework for the extraction of nuclear parameters is well established. These extracted parameters provide fundamental information on the structure of nuclei at the limits of stability. Vital information on both bulk and valence nuclear properties are derived and an exceptional sensitivity to changes in nuclear deformation is achieved. Laser spectroscopy provides the only mechanism for such studies in exotic systems and uniquely facilitates these studies in a model-independent manner. The accuracy of laser-spectroscopic-determined nuclear properties is very high. Requirements concerning production rates are moderate; collinear spectroscopy has been performed with production rates as few as 100 ions per second and laser-desorption resonance ionization mass spectroscopy (combined with beta-delayed neutron detection) has been achieved with rates of only a few atoms per second. This Technical Design Report describes a new Penning trap mass spectrometry setup as well as a number of complementary experimental devices for laser spectroscopy, which will provide a complete system with respect to the physics and isotopes that can be studied. Since MATS and LaSpec require high-quality low-energy beams, the two collaborations have a common beamline to stop the radioactive beam of in-flight produced isotopes and prepare them in a suitable way for transfer to the MATS and LaSpec setups, respectively.
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| 8. |
- Fraerman, A. A., et al.
(author)
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Magnetic force microscopy of helical states in multilayer nanomagnets
- 2008
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103:7, s. 073916-
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Journal article (peer-reviewed)abstract
- We have used magnetic force microscopy (MFM) to investigate noncollinear helical states in multilayer nanomagnets, consisting of a stack of single domain ferromagnetic disks separated by insulating nonmagnetic spacers. The nanomagnets were fabricated from a [Co/Si]x3 multilayer thin film structure by electron beam lithography and ion beam etching. The structural parameters (Co layer and spacer thicknesses) were optimized to obtain a clear spiral signature in the MFM contrast, taking into account the magnetostatic interaction between the layers. MFM contrast corresponding to the helical states with different helicities was observed for the optimized structure with Co layer thicknesses of 16, 11, and 8 nm, and with 3 nm Si spacer thickness.
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| 9. |
- Fraerman, A. A., et al.
(author)
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Magnetic force microscopy to determine vorticity direction in elliptical Co nanoparticles
- 2004
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In: Physics of low-Dimensional structures. - 0204-3467. ; 1-2, s. 35-40
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Journal article (peer-reviewed)abstract
- We present a magnetic force microscopy investigation into the magnetic properties of arrays of Co nanoparticles fabricated by electron be am lithography. Vorticity directions are determined in zero applied magnetic fields. Experimental dependence of height on stable magnetic states of the particles is investigated. The statistics of the vorticity direction distribution is discussed.
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| 10. |
- Rudenko, Oleg, et al.
(author)
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Control of the Self-Assembly Processes in a Droplet of a Colloidal Solution by an Acoustic Field
- 2010
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In: Acoustical Physics. - : Pleiades Publishing. - 1063-7710 .- 1562-6865. ; 56:6, s. 935-941
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Journal article (peer-reviewed)abstract
- The formation of structured films consisting of ensembles of micro- or nanoparticles and possessing preset functional characteristics is studied both experimentally and theoretically. The films are obtained by drying out droplets of colloidal solutions on a solid substrate under the acoustic effect produced by a standing SAW field.
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| 11. |
- Voloshin, V. A., et al.
(author)
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Interplay of structure, magnetism and resistivity of La0.5Ca0.54MnO3+x
- 2000
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In: Physics Letters A. - 0375-9601 .- 1873-2429. ; 271:02-jan, s. 121-127
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Journal article (peer-reviewed)abstract
- The structure of La0,5Ca0,5MnO3 is well known for T> 250 K and T( 150 K. But in the intermediate region some structure characteristics are difficult to understand [1]. This Letter studies in this temperature region the interrelation between structure and the experimental data like magnetism and resistivity on the basis of a vibron-electron dynamic equilibrium hypothesis. It has been shown that behavior of paramagnetic-to-ferromagnetic transition can be explaned in the framework of this hypothesis.
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| 12. |
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| 13. |
- Gusev, A. N., et al.
(author)
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Synthesis and photophysical properties of Zn(II) Schiff base complexes possessing strong solvent-dependent solid-state fluorescence
- 2018
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In: Polyhedron. - : Elsevier Ltd. - 0277-5387 .- 1873-3719. ; 155, s. 202-208
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Journal article (peer-reviewed)abstract
- The present article reports on the syntheses, crystal structures and luminescence properties of three solvate forms of a zinc(II) complex containing 4-{(E)-[(2-fluorophenyl)imino]methyl}-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one (HL). The reaction of zinc(II)acetate with the HL ligand in ethanol and acetonitrile led to the formation of two solvate analogues [Zn(L)2]·Solv (Solv – ethanol (1) and acetonitrile (2)). The properties of the [Zn(L)2]·Solv complexes were investigated by UV–Vis absorption and fluorescence emission spectroscopy, and the density functional theory calculations. Bader's topological analysis was performed to investigate the electronic peculiarities of Zn(II) polyhedra and non-covalent interactions within crystal packing of studied solvates.
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| 14. |
- Carra, Serena, et al.
(author)
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The growing world of small heat shock proteins : from structure to functions
- 2017
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In: Cell Stress and Chaperones. - : Springer Science and Business Media LLC. - 1355-8145 .- 1466-1268. ; 22:4, s. 601-611
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Journal article (peer-reviewed)abstract
- Small heat shock proteins (sHSPs) are present in all kingdoms of life and play fundamental roles in cell biology. sHSPs are key components of the cellular protein quality control system, acting as the first line of defense against conditions that affect protein homeostasis and proteome stability, from bacteria to plants to humans. sHSPs have the ability to bind to a large subset of substrates and to maintain them in a state competent for refolding or clearance with the assistance of the HSP70 machinery. sHSPs participate in a number of biological processes, from the cell cycle, to cell differentiation, from adaptation to stressful conditions, to apoptosis, and, even, to the transformation of a cell into a malignant state. As a consequence, sHSP malfunction has been implicated in abnormal placental development and preterm deliveries, in the prognosis of several types of cancer, and in the development of neurological diseases. Moreover, mutations in the genes encoding several mammalian sHSPs result in neurological, muscular, or cardiac age-related diseases in humans. Loss of protein homeostasis due to protein aggregation is typical of many age-related neurodegenerative and neuromuscular diseases. In light of the role of sHSPs in the clearance of un/misfolded aggregation-prone substrates, pharmacological modulation of sHSP expression or function and rescue of defective sHSPs represent possible routes to alleviate or cure protein conformation diseases. Here, we report the latest news and views on sHSPs discussed by many of the world’s experts in the sHSP field during a dedicated workshop organized in Italy (Bertinoro, CEUB, October 12–15, 2016).
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| 15. |
- Gusev, Alexey N., et al.
(author)
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Novel Zinc Complex with an Ethylenediamine Schiff Base for High-Luminance Blue Fluorescent OLED Applications
- 2019
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In: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 123:18, s. 11850-11859
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Journal article (peer-reviewed)abstract
- To explore the photophysical properties of coordination compounds with bright blue fluorescence, an azomethin-zinc complex was synthesized and characterized by various techniques (elemental analysis, thermogravimetry, and IR-mass-spectroscopy). The crystal structure was determined by X-ray diffraction analysis. Through thermal characterization, this complex was proved to have good thermal stability. Photoluminescence spectra were recorded, both in solution and in the solid state, and the complexes showed noteworthy photoluminescence with a maximum in the blue region. The results of time-dependent density functional theory calculations indicated that the origin of luminescence for the title complex is a combination of monomer and excimer emissions. The light emission performance of the zinc complex in organic light emitting diodes was investigated, and the results indicated superior electroluminescence properties as a blue fluorescent light source (max. brightness 17 000 cd/m(2), max. EQE = 5%).
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| 16. |
- Gusev, Alexey N., et al.
(author)
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Schiff Base Zinc(II) Complexes as Promising Emitters for Blue Organic Light-Emitting Diodes
- 2021
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In: ACS Applied Electronic Materials. - : American Chemical Society (ACS). - 2637-6113. ; 3:8, s. 3436-3444
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Journal article (peer-reviewed)abstract
- Organometallic blue fluorescent Zn(II) Schiff base complexes are synthesized and explored computationally in order to use them in organic electroluminescent heterostructures. Characterization of these pyrazolone-based azomethine-zinc complexes was accomplished by various physicochemical techniques to get insight into their applicability as an active layer in light-emitting diodes. All the complexes demonstrate high thermal stability and remarkable photoluminescence both in solution and in the solid state with maximum in the blue region. Quantum chemical calculations of the first exited electronic state and vertical singlet-singlet electronic transitions by means of time-dependent density functional theory calculations and results show that the origin of the luminescence for the target complexes refers to the intraligand charge transfer within the Schiff bases. The constructed light-emitting diodes demonstrate low input voltage (3.2-4.0 V), brightness at a level of 4300-11,600 Cd m(-2), and external quantum efficiency of up to 3.2%, which is a good value for purely fluorescent organic light-emitting diodes.
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| 17. |
- Pchelkin, Stepan S., et al.
(author)
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On Orbital Stabilization for Industrial Manipulators : Case Study in Evaluating Performances of Modified PD plus and Inverse Dynamics Controllers
- 2017
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In: IEEE Transactions on Control Systems Technology. - 1063-6536 .- 1558-0865. ; 25:1, s. 101-117
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Journal article (peer-reviewed)abstract
- Orbital stabilization is one of the available alternatives to the classical asymptotic stabilization, known as the reference tracking control, which is typically considered and implemented for controlling motions of industrial robot manipulators. Since asymptotic orbital stability means convergence of solutions of a closed-loop system to an orbit of a reference trajectory, instead of tracking it as a function of time, new feedback designs can potentially improve performance with respect to several key criteria for industrial manipulators such as absolute path accuracy for tool's motions and robustness to uncertainties in the model. The main outcomes of this paper are a new class of controllers that achieve asymptotic orbital stabilization of motions and a novel analytical method for analysis and redesign of system's dynamics using an excessive set of easy-to-compute transverse coordinates. The contributions have been validated in a series of experimental studies performed on a standard industrial robot ABB IRB 140 with the IRC5-system extended with an open control interface. The outcomes of the tests show that the proposed redesign allows achieving significantly reduced deviations of the actual trajectories from the desired ones at different ranges of speeds and for several different paths, often outperforming the state-of-the-art commercial implementations. A comprehensive discussion of one of such experiments is given.
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| 18. |
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| 19. |
- Gusev, V.A., et al.
(author)
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Intensification of the impact of high-intensity focused ultrasound (HIFU) with special spatiotemporal modulation
- 2013
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In: Acoustical Physics. - : Springer. - 1063-7710 .- 1562-6865. ; 59:1, s. 45-50
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Journal article (peer-reviewed)abstract
- The principle of forming a special form of powerful acoustic signals is proposed, which makes it possible to ensure precise spatiotemporal beam focusing. The introduction of a transverse-coordinate-dependent local wave frequency is suggested, due to which the equality of the formation lengths of a discontinuity for all rays is achieved. This thereby ensures an increase in nonlinear absorption; as a result, the temperature and radiation action of focused ultrasound on the medium increase.
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| 20. |
- Gusev, V. A., et al.
(author)
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Nonlinear sound in a gas-saturated sediment layer
- 2015
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In: Acoustical Physics. - : Maik Nauka/Interperiodica. - 1063-7710 .- 1562-6865. ; 61:2, s. 152-164
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Journal article (peer-reviewed)abstract
- Wave propagation in a near-bottom layer containing gas bubbles is analyzed. Evolution equations are derived for intense acoustic waves and wave beams in a medium with an inhomogeneous bubble distribution. The field of an intense beam along the axis of the focusing sound channel is calculated. The coefficients of reflection and passage of sound from a homogeneous medium into a bubble layer and back again are calculated. It is shown that the near-bottom layer can effectively trap rays incident on it and ensure a waveguide propagation character. The presence of bubbles increases both the interval of angles at which the wave penetrates the layer and the interval of angles at which rays undergo total internal reflection and do not depart the layer. The acoustic field in the layer from a point source is calculated.
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| 21. |
- Gusev, V.A., et al.
(author)
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The Field of Radiative Forces and the Acoustic Streaming in a Liquid Layer on a Solid Half-Space
- 2010
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In: Acoustical Physics. - : Pleiades Publishing. - 1063-7710 .- 1562-6865. ; 56:6, s. 861-870
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Journal article (peer-reviewed)abstract
- The acoustic field and the field of radiative forces that are formed in a liquid layer on a solid substrate are calculated for the case of wave propagation along the interface. The calculations take into account the effects produced by surface tension, viscous stresses at the boundary, and attenuation in the liquid volume on the field characteristics. The dispersion equations and the velocities of wave propagation are determined. The radiative forces acting on a liquid volume element in a standing wave are calculated. The structure of streaming is studied. The effect of streaming on small size particles is considered, and the possibilities of ordered structure formation from them are discussed.
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| 22. |
- Rudenko, Oleg, et al.
(author)
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Self-similar solutions of a Burgers-type equation with quadratically cubic nonlinearity
- 2016
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In: Doklady. Mathematics. - : Maik Nauka/Interperiodica. - 1064-5624 .- 1531-8362. ; 93:1, s. 94-98
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Journal article (peer-reviewed)abstract
- Self-similar solutions are found for a quadratically cubic second-order partial differential equation governing the behavior of nonlinear waves in various distributed systems, for example, in some metamaterials. They are compared with self-similar solutions of the Burgers equation. One of them describing a single unipolar pulse is shown to satisfy both equations. The other self-similar solutions of the quadratically cubic equation behave differently from the solutions of the Burgers equation. They are constructed by matching the positive and negative branches of the solution, so that the function itself and its first derivative are continuous. One of these solutions corresponds to an asymmetric solitary N-wave of the sonic shock type. Self-similar solutions of a quadratically cubic equation describing the propagation of cylindrically symmetric waves are also found.
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