A general approach is applied to study a new type of intrinsic spatially localized vibrational modes in a defect free nonlinear crystal lattice, i.e., discrete breathers (DBs). For that, dynamics of ...eight delocalized nonlinear vibrational modes (DNVMs) of two-dimensional triangular lattice is investigated in three-dimensional single crystal of hcp Ti. Molecular dynamics simulations are performed using two interatomic potentials (Ti_EAM and Ti_MEAM). The eight DNVMs modeled with Ti_EAM potential are found to be unstable and dissipate their vibrational energy very rapidly. The usage of Ti_MEAM interatomic potential allows to excite stable two-dimensional (planar) DBs. These localized vibrational modes can be called DBs, since the frequency of atomic oscillations is above the upper edge of the phonon spectrum of Ti, and the atomic oscillations are localized in one spatial direction and delocalized in the other two directions. The lifetimes of the two-dimensional DBs are in the range of 5–14 ps, while the maximal lifetime of DBs excited on the basis of DNVM 7 is circa 28 ps. These DBs can accumulate vibrational energy, which is in the range of 0.1–0.5 eV per atom. The stable two-dimensional DBs are characterized by a hard type of nonlinearity. A comparison with analogous two-dimensional DBs in fcc metals are undertaken. The obtained results make a significant contribution to the study of DBs in metals and will be important for understanding the influence of intrinsic localized vibrational modes on the physical properties of materials.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Superconducting quantum systems (artificial atoms) have been recently successfully used to demonstrate on-chip effects of quantum optics with single atoms in the microwave range. In particular, a ...well-known effect of four wave mixing could reveal a series of features beyond classical physics, when a non-linear medium is scaled down to a single quantum scatterer. Here we demonstrate the phenomenon of quantum wave mixing (QWM) on a single superconducting artificial atom. In the QWM, the spectrum of elastically scattered radiation is a direct map of the interacting superposed and coherent photonic states. Moreover, the artificial atom visualises photon-state statistics, distinguishing coherent, one- and two-photon superposed states with the finite (quantised) number of peaks in the quantum regime. Our results may give a new insight into nonlinear quantum effects in microwave optics with artificial atoms.
In this work, a series of PEGylated manganese-zinc ferrite mixed (PEG-Mn
1-x
Zn
x
Fe
2
O
4
) nanoparticles with varying concentrations of zinc ions (x = 0.0, 0.25, 0.4, 0.5, 0.75, 1.0) were ...synthesized using a solvothermal approach to investigate their physicochemical and magnetic hyperthermia properties through a range of analytical techniques, including TEM, XRF, XRD, FTIR, VSM, and magnetic hyperthermia. The PEG-Mn
1-x
Zn
x
Fe
2
O
4
nanoparticles exhibited a nearly spherical shape and diameters less than 30 nm. The particle size decreased from 27 to 11.6 nm with an increasing amount of zinc (x = 0.0–0.5). The saturation magnetization (M
S
) value decreased with the rising Zn content, ranging from 77.8 to 30.7 emu/g. The addition of zinc led to a reduction in the specific absorption rate (SAR) of the material. This decrease in the SAR parameter was associated with a decline in the intrinsic loss power (ILP) value, varying from 0.264 nH m
2
/kg for MnFe
2
O
4
to 0.037 nH m
2
/kg for ZnFe
2
O
4
. Consequently, these PEG-Mn
1-x
Zn
x
Fe
2
O
4
nanoparticles exhibit potential as candidates for magnetic fluid hyperthermia applications.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The heaviest elements to have been chemically characterized are seaborgium (element 106), bohrium (element 107) and hassium (element 108). All three behave according to their respective positions in ...groups 6, 7 and 8 of the periodic table, which arranges elements according to their outermost electrons and hence their chemical properties. However, the chemical characterization results are not trivial: relativistic effects on the electronic structure of the heaviest elements can strongly influence chemical properties. The next heavy element targeted for chemical characterization is element 112; its closed-shell electronic structure with a filled outer s orbital suggests that it may be particularly susceptible to strong deviations from the chemical property trends expected within group 12. Indeed, first experiments concluded that element 112 does not behave like its lighter homologue mercury. However, the production and identification methods used cast doubt on the validity of this result. Here we report a more reliable chemical characterization of element 112, involving the production of two atoms of 283112 through the alpha decay of the short-lived 287114 (which itself forms in the nuclear fusion reaction of 48Ca with 242Pu) and the adsorption of the two atoms on a gold surface. By directly comparing the adsorption characteristics of 283112 to that of mercury and the noble gas radon, we find that element 112 is very volatile and, unlike radon, reveals a metallic interaction with the gold surface. These adsorption characteristics establish element 112 as a typical element of group 12, and its successful production unambiguously establishes the approach to the island of stability of superheavy elements through 48Ca-induced nuclear fusion reactions with actinides.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Delocalized nonlinear vibrational modes (DNVMs) are relatively new dynamical objects that can be used for testing interatomic potentials and for classification and finding new types of ...discrete breathers. In this work, for the first time, multi-component DNVMs in a single crystal of fcc nickel are studied using molecular dynamics method. Previously discovered two one-component DNVMs are used to construct and investigate properties of all possible two- and three-component superpositions. A quasi-periodic energy exchange between components in multi-component DNVMs is described. If the amplitudes of the one-component DNVMs in a superposition differ by less than four times, then an equivalent energy exchange between them is observed. Otherwise, an unequal energy exchange takes place, i.e. when the high-amplitude component gives up only a part of its energy leading to a slight increase in the amplitude of another component. The DNVMs consisting of two- and three-components have a lifetime of more than 10 ps as long as the initial atomic amplitudes do not exceed 0.08 Å. An increase in the initial amplitude leads to a substantial decrease in the lifetime due to the rapidly developing modulational instability. Some superpositions of modes with the same initial amplitudes of the components can transform into a one-component DNVM, while others remain multi-component ones. The results obtained in this work demonstrate the existence of multi-component DNVMs, being a superposition of two or three components, which significantly expands our understanding of their dynamics in an fcc lattice.
Gallium chalcogenides are promising building blocks for novel van der Waals heterostructures. We report on the low-temperature micro-photoluminescence (PL) of GaTe and GaSe films with thicknesses ...ranging from 200 nm to a single unit cell. In both materials, PL shows a dramatic decrease by 104-105 when film thickness is reduced from 200 to 10 nm. Based on evidence from continuous-wave (cw) and time-resolved PL, we propose a model explaining the PL decrease as a result of non-radiative carrier escape via surface states. Our results emphasize the need for special passivation of two-dimensional films for optoelectronic applications.
Microwires and microstripes obtained by extraction from melt PrDyFeCoB were investigated. The angular dependence of the magnetic moment of microwires shows a qualitative shape changing in a strong ...magnetic field close to the magnetization saturation field of 4–5 kOe. Appearance of an additional maximum of the magnetic moment on the angular dependence in strong field is explained using the multi-domain Stoner–Wohlfahrt (SW) model. Dividing the hysteresis loop of the microwires into two components shows that the coercive force of the α-FeCo phase (500–700 Oe) defines the hysteresis loop width in the weak field, while the coercive force of the phase 2-14-1 (10 kOe) corresponds to the side segments of the loop. Striped domains and their evolution during magnetization of the microstripes were revealed using Kerr magnetooptical microscopy.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
For various materials, rapid generation of results is always critical. Particle-size analysis of processing products using a laser-based particle-size analyzer is a valid alternative to the ...traditional sizing test. The article presents the results of studies conducted using Microsizer 201C equipment by the example of layered aluminosilicates and metal powders for additive manufacturing. The size analysis for these products is generally complicated by their ability to stick and agglomerate. Ultrasonic mixing does not harm the material analyzed and promotes uniform distribution of the sample during analysis. The results of granulometric analysis of kaolin ores obtained after different heat treatment are presented. The results of air-electric classification of metal powders obtained after vibration disintegration of metal chips are presented. The variety of raw materials shows a wide range of applications of this method in industry.
Mitral regurgitation (MR) is the second most common valvular heart disease in terms of prevalence and frequency of indications for cardiac surgery. Severe MR is characterized by a significant ...decrease in exercise tolerance and high mortality. The most common cause of organic MR is degenerative diseases. A detailed and systematic assessment of mitral valve and MR mechanisms is critical for the management of these patients, planning the type and timing of surgical intervention. Echocardiography plays a leading role among modern imaging methods in such patients. Examination of a patient with MR should include determining the pathogenesis of regurgitation, its severity and hemodynamic consequences. The aim of the review was to analyze the potential for using conventional and novel echocardiographic parameters to select the management strategy for patients with degenerative mitral regurgitation.
Discrete breathers (DBs) have been described among pure metals with face-centered cubic (FCC) and body-centered cubic (BCC) lattice, but for hexagonal close-packed (HCP) metals, their properties are ...little studied. In this paper, the properties of standing and moving DBs in beryllium HCP metal are analyzed by the molecular dynamics method using the many-body interatomic potential. It is shown that the DB is localized in a close-packed atomic row in the basal plane, while oscillations with a large amplitude along the close-packed row are made by two or three atoms, moving in antiphase with the nearest neighbors. Dependences of the DB frequency on the amplitude, as well as the velocity of the DB on its amplitude and on parameter δ, which determines the phase difference of the oscillations of neighboring atoms, are obtained. The maximum velocity of the DB movement in beryllium reaches 4.35 km/s, which is 33.7% of the velocity of longitudinal sound waves. The obtained results supplement our concepts about the mechanisms of localization and energy transport in HCP metals.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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