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The structure and electromagnetic properties of a lithium ferrite, Li0.5Fe2.5O4, fabricated by an additive manufacturing process based on extrusion printing of ferrite samples with a binder substance followed by hightemperature sintering are studied. A preliminary ferrite-powder synthesis is carried out by the solid-phase method using iron oxide and lithium carbonate. The ferrite paste for printing is prepared using a binder based on ethyl cellulose and terpineol. The samples measuring 100 and 500 μm are fabricated by extrusion in a Voltera V-one 3D printer. The samples are sintered in a laboratory furnace at 1100°C. The microstructure and properties of the resulting ferrites depend on the printed layer thickness. The samples are characterized by a relative density of 72 and 76%, a specific saturation magnetization of 50 and 62 emu/g, a Curie temperature of 625 and 630°C, and a specific electric resistivity of 1.1·1010 and 1.6·109 Ω·cm for the 100 and 500 μm-thick samples, respectively. [ABSTRACT FROM AUTHOR]

We have studied the potential barriers for the penetration of atomic beryllium or boron inside the C60 fullerene by performing density functional theory (DFT) calculations with three variants for the exchange and correlation: B3LYP (hybrid functional), PW91, and PBE. Four principal trajectories to the inner part of C60 for the penetrating atom have been considered: through the center of six-member-carbon ring (hexagon), five-member-carbon ring (pentagon), and also through the center of the double C–C bond (D-bond) and the center of the single C–C bond (S-bond). Averaging over the three DFT variants yields the following barriers for beryllium penetrating inside a deformable fullerene: 3.2 eV (hexagon), 4.8 eV (S-bond), 5.3 eV (D-bond), 5.9 eV (pentagon). These barriers correspond to the slow and adiabatic penetration of Be, in contrast to the fast (non-adiabatic) penetration through the rigid cage of C60 resulting in 5.6 eV (hexagon), 16.3 eV (pentagon), 81.8 eV (S-bond), and 93.4 eV (D-bond). The potential barriers for the boron penetrating inside deformable/rigid C60 are 3.7/105.4 eV (D-bond), 4.0/86.8 eV (S-bond), 4.7/7.8 eV (hexagon), 6.8/14.0 eV (pentagon). [ABSTRACT FROM AUTHOR]

We study the nature of chemical bonding of the thorium atom with novel BN-based nanomaterials: fullerenes B 30 N 30 , B 12 N 8 , B 8 N 12 , and the BN analog of coronene—B 12 N 12 H 12 , used as a representative molecular fragment of the two dimensional hexagonal BN-sheet. Our ab initio calculations are performed within the dispersion-corrected density functional approach with a hybrid exchange-correlation potential. The smallest 20-atom BN-fullerenes B 12 N 8 , B 8 N 12 proposed by us are shown to be stable and should be observable experimentally. Thorium is found at the center of these structures pushing the outer shell of atoms farther away. The shape of the B 12 N 8 -cage in Th@B 12 N 8 is conserved, while the shape of the B 8 N 12 molecule in Th@B 8 N 12 is largely deformed. The initially planar structure of B 12 N 12 H 12 in the presence of thorium becomes corrugated, demonstrating pronounced off-plane displacements under the thorium atom. Other four-valent metals (Ti, Zr, and Hf) also cause off-plane displacements of B and N atoms albeit to a much smaller scale. In the 60-atom fullerene B 30 N 30 , which is the BN analog of C 60 , two conformations of Th@B 30 N 30 are found: one is with thorium facing the hexagon with one B–B and one N–N covalent bonds and a second, lying 0.79 eV higher, with thorium close to the center of pentagon with one B–B covalent bond. [ABSTRACT FROM AUTHOR]

Nonlinear phenomena similar to the Belousov–Zhabotinsky reaction (autocatalytic oscillations of the population of high-spin and low-spin multielectron states of a transition metal ion) in open systems with spin crossover near bistability are considered. The conditions for possible experimental observation of autocatalytic oscillations of the magnetization in magnetically ordered systems with spin crossover are analyzed. [ABSTRACT FROM AUTHOR]

Bioinert materials such as the zirconium dioxide and aluminum oxide are widely used in surgery and dentistry due to the absence of cytotoxicity of the materials in relation to the surrounding cells of the body. However, little attention has been paid to the study of metabolic processes occurring at the implant–cell interface. The metabolic activity of mouse 3T3 fibroblasts incubated on yttrium-stabilized zirconium ceramics cured with aluminum oxide (ATZ) and stabilized zirconium ceramics (Y-TZP) was analyzed based on the ratio of the free/bound forms of cofactors NAD(P)H and FAD obtained using two-photon microscopy. The results show that fibroblasts incubated on ceramics demonstrate a shift towards the free form of NAD(P)H, which is observed during the glycolysis process, which, according to our assumptions, is related to the porosity of the surface of ceramic structures. Consequently, despite the high viability and good proliferation of fibroblasts assessed using an MTT test and a scanning electron microscope, the cells are in a state of hypoxia during incubation on ceramic structures. The FLIM results obtained in this work can be used as additional information for scientists who are interested in manufacturing osteoimplants. [ABSTRACT FROM AUTHOR]

An approximation of the turbulent moments of the atmospheric convective layer is based on a variant of the local similarity theory using the concepts of the semiempirical theory of Prandtl turbulence. In the proposed variant of the local similarity theory, the second moment of vertical velocity and the "spectral" Prandtl mixing length are used as basic parameters. This approach allows us to extend Prandtl's theory to turbulent moments of vertical velocity and buoyancy and additionally offer more than ten new approximations. A comparison of the proposed approximation with other variants of the theory of local similarity is considered. It is shown that the selected basic parameters significantly improve the agreement between the local similarity approximations and experimental data. The approximations are consistent with observations in the turbulent convective layer of the atmosphere, the upper boundary of which nearly corresponds to the lower boundary of the temperature inversion. Analytical approximations of local similarity can find applications in the construction of high-order moment closures in the vortex of resolving numerical turbulence models, as well as in the construction of "mass-flux" parametrization. [ABSTRACT FROM AUTHOR]

A nonlinear integral equation arising from a parametric closure of the third spatial moment in the single-species model of logistic dynamics of U. Dieckmann and R. Law is analyzed. The case of piecewise constant kernels is studied, which is important for further computer modeling. Sufficient conditions are found that guarantee the existence of a nontrivial solution to the equilibrium equation. The use of constant kernels makes it possible to obtain more accurate results compared to earlier works, in particular, more accurate estimates for the L1 norm of the solution and for the closure parameter are obtained. [ABSTRACT FROM AUTHOR]

A variant of the local similarity theory is considered, assuming a priori specification of two basic dimensional parameters: the second moment of vertical velocity and the "spectral" Prandtl mixing length. Such selection of basic parameters lets us interpret the algebraic formulas of Prandtl's semiempirical turbulence theory for the coefficients of turbulent heat transfer and kinetic energy dissipation as relationships of the local similarity theory. A priori approximations of the basic parameters are based on known relationships and consider the upper boundary of the convective layer as a solid wall. Within the framework of local similarity theory, approximations for the turbulent moments of buoyancy and vertical velocity of arbitrary order are also proposed. The correspondence of these approximations to experimental data has been established in both air and water mediums, as well as in the results of numerical modeling. Such correspondence allows us to conclude that a wide class of vertical profiles of turbulent moments in a windless convective layer depends only on two basic parameters: the second moment of vertical velocity and the "spectral" Prandtl mixing length. The obtained result indicates the universal nature of the theory of local similarity and is a significant addition to the semiempirical Prandtl theory. [ABSTRACT FROM AUTHOR]

Our recent work on multiple locations of boron atoms in the exohedral and endohedral C60 fullerene, [1], carried out within the Hartree-Fock method with the second order Møller-Plesset perturbation theory MP2 (HF-MP2), prompted recently a comment from Xu and Hou, [2], who have performed several density functional theory (DFT) calculations using DFT functionals of different complexity. In three out of five cases considered in our work, DFT calculations give the same ground state confirmations whereas in two cases optimal configurations have turned out to be different. However, depending on the choice of the exchange-correlation functional, the geometry optimization within DFT can also result in different ground state confirmations. The energy balance between nearest confirmations in these molecular complexes is subtle, and various methods can give different ground state structures. We therefore argue that the presented DFT calculations are not benchmark, and their results should be compared with ours (HF-MP2) on equal ground. We also present additional HF geometry optimizations with the 6-31G* basis set, which confirm the ground state confirmations obtained at the HF/6-31G level. [ABSTRACT FROM AUTHOR]

Analytical expressions for spontaneous emission probability in the vicinity of nanowire for the emitter oriented in axial, radial and azimuthal direction in respect to the nanowire axis, has been obtained. Directionality of emission and probability of emission have been calculated for various positions of emitter. Enhancement of the spontaneous emission probability by one order of magnitude, and formation of the sharp directionality diagram has been demonstrated. [ABSTRACT FROM AUTHOR]

The action of tetraalkylammonium ions, from tetrametylammonium (TMA) to tetrapentylammonium (TPtA), on the recombinant and native acid-sensing ion channels (ASICs) was studied using the patch-clamp approach. The responses of ASIC1a, ASIC2a, and native heteromeric ASICs were inhibited by TPtA. The peak currents through ASIC3 were unaffected, whereas the steady-state currents were significantly potentiated. This effect was characterized by an EC50 value of 1.22 ± 0.12 mM and a maximal effect of 3.2 ± 0.5. The effects of TPtA were voltage-independent but significantly decreased under conditions of strong acidification, which caused saturation of ASIC responses. Molecular modeling predicted TPtA binding in the acidic pocket of closed ASICs. Bound TPtA can prevent acidic pocket collapse through a process involving ASIC activation and desensitization. Tetraethylammonium (TEA) inhibited ASIC1a and native ASICs. The effect was independent of the activating pH but decreased with depolarization, suggesting a pore-blocking mechanism. [ABSTRACT FROM AUTHOR]

Recent research has demonstrated the high potential of grazing-emission X-ray fluorescence as a nanometrology tool for structures with complex 3D architecture. The technique now allows separate reconstruction of the spatial atomic distributions of different chemical elements both vertically and laterally, which opens up new and interesting applications in the nanofabrication industry. This study compares grazing-emission fluorescence with the well established grazing-incidence X-ray fluorescence method. The comparison uses a simple 1D thin-film structure. Reconstruction of the structure by both methods is performed and the statistical uncertainties of these reconstructions are compared by means of Monte Carlo Markov-chain simulations. For the forward model a semi-analytic approach is derived which allows simulation of the fluorescence intensity. This approach takes into account both grazing-incidence and grazing-emission cases. It also accounts for an even more complex physical phenomenon, the anomalous Kossel effect. Finally, using this semi-analytic approach, an experimental scheme combining grazing-incidence and grazingemission X-ray fluorescence is studied theoretically. [ABSTRACT FROM AUTHOR]

Lymphedema is a pathology caused by poor lymphatic flow which may lead to complete disability. Currently, precise, non-invasive techniques for quantifying lymphedema are lacking. In this paper, the results of an in vivo assessment of lymphedema via a developed small-animal model using the hindlimbs of rats and an optical coherence tomography (OCT) technique are presented. This model of lymphedema was based on a surgical lymph node resection and subsequent two-step X-ray exposure. The development of lymphedema was verified via the histological examination of tissue biopsies. The properties of the lymphedematous skin were analyzed in vivo and compared with healthy skin via OCT. The main differences observed were (1) a thickening of the stratum corneum layer, (2) a thinning of the viable epidermis layer, and (3) higher signal attenuation in the dermis layer of the lymphedematous skin. Based on the distribution of the OCT signal's intensity in the skin, a machine learning algorithm was developed which allowed for a classification of normal and lymphedematous tissue sites with an accuracy of 90%. The obtained results pave the way for in vivo control over the development of lymphedema. [ABSTRACT FROM AUTHOR]

The physics of high- T c superconducting cuprates is obscured by the effect of strong electronic correlations. One way to overcome this problem is to seek an exact solution at least within a small cluster and expand it to the whole crystal. Such an approach is at the heart of cluster perturbation theory (CPT). Here, we developed CPT for the dynamic spin and charge susceptibilities (spin-CPT and charge-CPT), with the correlation effects explicitly taken into account by the exact diagonalization. We applied spin-CPT and charge-CPT to the effective two-band Hubbard model for the cuprates obtained from the three-band Emery model and calculated one- and two-particle correlation functions, namely, a spectral function and spin and charge susceptibilities. The doping dependence of the spin susceptibility was studied within spin-CPT and CPT-RPA, that is, the CPT generalization of the random phase approximation (RPA). In the underdoped region, both our methods resulted in the signatures of the upper branch of the spin excitation dispersion with the lowest excitation energy at the (π , π) wave vector and no presence of low-energy incommensurate excitations. In the high doping region, both methods produced a low energy response at four incommensurate wave vectors in qualitative agreement with the results of the inelastic neutron scattering experiments on overdoped cuprates. [ABSTRACT FROM AUTHOR]

A new mechanism of the photoinduced enhancement of the excitonic order in strongly correlated electron systems with the spin crossover through the generation of a massive mode in the spectrum of collective excitations is demonstrated. [ABSTRACT FROM AUTHOR]

Background: Among available breast biopsy techniques, ultrasound (US)‐guided biopsy is preferable because it is relatively inexpensive and provides live imaging feedback. The availability of magnetic resonance imaging (MRI)‐3D US image fusion would facilitate US‐guided biopsy even for US occult lesions to reduce the need for expensive and time‐consuming MRI‐guided biopsy. In this paper, we propose a novel Automated Cone‐based Breast Ultrasound Scanning and Biopsy System (ACBUS‐BS) to scan and biopsy breasts of women in prone position. It is based on a previously developed system, called ACBUS, that facilitates MRI‐3D US image fusion imaging of the breast employing a conical container filled with coupling medium. Purpose: The purpose of this study was to introduce the ABCUS‐BS system and demonstrate its feasibility for biopsy of US occult lesions. Method: The biopsy procedure with the ACBUS‐BS comprises four steps: target localization, positioning, preparation, and biopsy. The biopsy outcome can be impacted by 5 types of errors: due to lesion segmentation, MRI‐3D US registration, navigation, lesion tracking during repositioning, and US inaccuracy (due to sound speed difference between the sample and the one used for image reconstruction). For the quantification, we use a soft custom‐made polyvinyl alcohol phantom (PVA) containing eight lesions (three US‐occult and five US‐visible lesions of 10 mm in diameter) and a commercial breast mimicking phantom with a median stiffness of 7.6 and 28 kPa, respectively. Errors of all types were quantified using the custom‐made phantom. The error due to lesion tracking was also quantified with the commercial phantom. Finally, the technology was validated by biopsying the custom‐made phantom and comparing the size of the biopsied material to the original lesion size. The average size of the 10‐mm‐sized lesions in the biopsy specimen was 7.00 ± 0.92 mm (6.33 ± 1.16 mm for US occult lesions, and 7.40 ± 0.55 mm for US‐visible lesions). Results: For the PVA phantom, the errors due to registration, navigation, lesion tracking during repositioning, and US inaccuracy were 1.33, 0.30, 2.12, and 0.55 mm. The total error was 4.01 mm. For the commercial phantom, the error due to lesion tracking was estimated at 1.10 mm, and the total error was 4.11 mm. Given these results, the system is expected to successfully biopsy lesions larger than 8.22 mm in diameter. Patient studies will have to be carried out to confirm this in vivo. Conclusion: The ACBUS‐BS facilitates US‐guided biopsy of lesions detected in pre‐MRI and therefore might offer a low‐cost alternative to MRI‐guided biopsy. We demonstrated the feasibility of the approach by successfully taking biopsies of five US‐visible and three US‐occult lesions embedded in a soft breast‐shaped phantom. [ABSTRACT FROM AUTHOR]

A dynamical analog of the prime ideals for simple non-commutative rings is introduced. We prove a factorization theorem for the dynamical ideals. The result is used to classify the surface knots and links in the smooth four-dimensional manifolds. [ABSTRACT FROM AUTHOR]

Features of the formation of the magnetic structure and the exciton Bose–Einstein condensate phase of magnetic excitons in strongly correlated systems near the spin crossover have been considered with the effective Hamiltonian obtained from the two-band Hubbard–Kanamori model. The coexistence of antiferromagnetism and exciton condensate, as well as the appearance of the long-range excitonic antiferromagnetic order even in the absence of the interatomic exchange interaction, has been revealed. The role of the electron–phonon coupling has been considered. [ABSTRACT FROM AUTHOR]

It is proved that the rank of an elliptic curve is one less the arithmetic complexity of the corresponding non-commutative torus. As an illustration, we consider a family of elliptic curves with complex multiplication. [ABSTRACT FROM AUTHOR]

The effect of mechanical activation of the mixture of Fe2O3-Co3O4-ZnO reagents on thermal synthesis of cobalt-zinc ferrite (Co0.5Zn0.5Fe2O4) was studied using X-ray powder diffraction and thermal analyses. The initial oxide powders were mixed using a Retsch Emax high energy ball mill to homogenize the mixture and enhance the reactivity. Mechanical activation was performed in air for 30 and 60 min. Thermal synthesis was performed at 900 °C for 4 h. X-ray diffraction analysis revealed an increase in the intensity of reflections that belong to spinel phases at increased rotational speed of the grinding vials and grinding duration. The patterns of formation of the final ferrite phase depending on the modes of mechanical pre-activation were showed by thermal analysis. It was shown that mechanical pre-activation of a mixture of initial reagents in a high-energy ball mill facilitates the formation of the ferrite phase of the given composition. The Curie temperature was determined for Co0.5Zn0.5Fe2O4 ferrite (~ 178 °C) by thermal synthesis. Kindly check and confirm whether the corresponding author is correctly identified. Corresponding author identified correctl [ABSTRACT FROM AUTHOR]

The paper addresses the study of the effect of different milling modes on the reactivity of the initial α-Fe2O3 and Li2CO3 powders by thermogravimetry and differential scanning calorimetry to obtain lithium ferrite of Li0.5Fe2.5O4 chemical composition. The formation of the magnetic phase of ferrite was monitored by thermogravimetric analysis in a magnetic field. The powder mixture was mechanically activated in air at different processing time and vial rotation speed using a planetary mill. It was found that the reactivity of the initial reagents depends on milling energy intensity. A varied milling mode changes the pattern of the interaction between reagents, and therefore a temperature range, the number of stages and the rate of lithium ferrite formation. In these conditions, an increased vial rotation speed during milling makes a more significant contribution to the change in the powder reactivity as compared to longer milling time. [ABSTRACT FROM AUTHOR]

When the strength of light–matter interaction (the Rabi splitting) in mesocavities is comparable to the energy spacing between the cavity modes, an exciton mode is coupled simultaneously to a number of optical modes. It has recently been demonstrated that a nonmonotonic dependence of the population of polariton states in mesocavities on the pump intensity is possible. Here, it is shown that an additional quasistationary state may appear in the hysteresis region and the time spent by the system in this state depends on the pump intensity. [ABSTRACT FROM AUTHOR]

The effect of ion polishing in sputter deposited W/Si multilayer mirrors with a d-spacing of 2.5 nm was studied. 0.1 to 0.5 nm of Si were etched with 100 eV Ar+ ions. This process resulted in a pronounced reduction in diffused scattering, measured at wavelengths about 0.1 nm. However, CuKa X-ray specular reflectivity and AFM showed only a marginal reduction of the roughness amplitude in the systems. Furthermore, the soft X-ray reflectivity at 0.84 and 2.4 nm did not show any changes after the ion polishing as compared to the nonpolished structures. Grazing incidence X-ray reflectivity (GIXR) analysis revealed that there was no pure W present in the deposited multilayers, with WSi2 being formed instead. As a result, it was concluded that the initial roughness in W/Si multilayers grown by magnetron sputtering is not the major factor in the reflectivity deviation from the calculated value for an ideal system. Nevertheless, the grazing incidence small-angle X-ray scattering (GISAXS) analysis revealed that ion polishing reduces the vertical propagation of roughness from layer to layer by a factor of two, as well as favorably affecting the lateral correlation length and Hurst parameter. These improvements explain the reduction of diffused X-ray scattering at 0.1 nm by more than an order of magnitude, which is relevant for applications like high resolution XRD analysis. [ABSTRACT FROM AUTHOR]

A detailed theoretical review of phase retrieval algorithms, including the generalized Gerchberg–Saxton algorithm and some of its modifications, is presented. The possibility of applying phase retrieval algorithms to study the magnetic domain structure by dichroic coherent diffractive imaging is investigated on numerical examples. An optimal strategy for analyzing experimental data, stable to their nonidealities, is developed. [ABSTRACT FROM AUTHOR]

In this paper, we analyze a system of nonlinear integral equations resulting from the three-parameter closure of the third spatial moments in the logistic dynamics model of U. Dieckmann and R. Law in the multi-species case. Specifically, the conditions under which the solution of this system is stable with respect to the closure parameters are investigated. To do this, the initial system of equations is represented as a single operator equation in a special Banach space, after which the generalized fixed point principle is applied. [ABSTRACT FROM AUTHOR]

In this paper, the measurement and modeling of optical properties in the terahertz (THz) range of adipose tissue and its components with temperature changes were performed. Spectral measurements were made in the frequency range 0.25–1 THz. The structural models of main triglycerides of fatty acids are constructed using the B3LYP/6-31G(d) method and the Gaussian03, Revision B.03 program. The optical density (OD) of adipose tissue samples decreases as temperature increases, which can be associated mostly with the dehydration of the sample. Some inclusion of THz wave scattering suppression into the OD decrease can also be expected due to refractive index matching provided by free fatty acids released from adipocytes at thermally induced cell lipolysis. It was shown that the difference between the THz absorption spectra of water and fat makes it possible to estimate the water content in adipose tissue. The proposed model was verified on the basis of molecular modeling and a comparison with experimental data for terahertz spectra of adipose tissue during its heating. Knowing the exact percentage of free and bound water in adipose tissue can help diagnose and monitor diseases, such as diabetes, obesity, and cancer. [ABSTRACT FROM AUTHOR]

A phosphate flame-retardant hardener (PFH) produced on the basis of industrial orthophosphoric acid and acetic anhydride was proposed for reducing the combustibility and revealing the natural texture of wood. Under fire conditions, phosphorus-containing compounds are able to decompose with formation of polyphosphoric acids providing a barrier coating on the combustion surface, as well as of substances inhibiting free-radical combustion, thereby reducing the rate of combustion and heat release. Wood surface treatment with the PFH was shown to reveal the natural texture of wood as a result of the reactions between the hydrolysis products of cellulose with the lignin components by the mechanism operating in the formation of triphenylmethane dyes. It was demonstrated that specifically the phenolic components of lignin participate in the formation of colored compounds, since cellulose with 90% lignin removed and cotton roving are not colored by the PFH. Softwoods are colored more strongly than hardwoods because of a higher lignin content. A complete scheme of reactions responsible for the appearance of colored structures in the wood texture in the presence of the PFH and atmospheric oxygen was proposed. A mechanism of thermal decomposition of cellulose during combustion in the presence of the PFH, resulting in predominant formation of a carbonaceous residue, was considered. From the quantitative data provided by the experiments on burning Whatman filter papers impregnated with the PFH, catalysis of the coke formation and enhancement of the coke yield were inferred. It was concluded that treatment with the PFH provides decorative appearance to wood and produces a protective effect thereon via reducing combustibility. A system of transparent decorative fire-resistant wood finishing was proposed, in which the PFH performs the function of a flame retardant and Porenbeize, and as well as of a hardener for epoxy varnish finish coating. [ABSTRACT FROM AUTHOR]

The paper deals with the analysis of a system of nonlinear integral equations resulting from the three-parameter closure of the third spatial moment in the Dieckmann–Law model in the case of an -species community in an -dimensional space. For the analysis of its solvability, this system is represented as an operator equation in a Banach space of a special form. Sufficient conditions for the existence of a nontrivial solution are stated using a generalized fixed point principle. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method for 3D model compression with fast GPU-accelerated decompression. This method applies on-the-fly decompression directly in the process of rasterization or ray tracing and allows us to fit three to eight times more geometry into the same volume of GPU memory. For rasterization, we implement two variants of decompression: via geometry and via mesh shaders. For ray tracing, we use hardware acceleration with the Vulkan VK_KHR_ray_tracing_pipeline extension and propose a BVH tree leaf caching technique, which speeds up rendering nearly twofold. The conclusions made in the process of performance evaluation of the proposed method can be useful to design hardware support for 3D model compression on future GPUs, because we ran into some hardware limitations of existing GPUs. [ABSTRACT FROM AUTHOR]

In this paper, the influence of surface modification on the characteristics and properties of AlN thin films on Si and glass-ceramics substrates is investigated. The surface modification was made at various parameters of argon cluster ions. By using XRD and Raman spectroscopy, it was shown that the obtained AlN films have a hexagonal structure with a characteristic direction of texturing along the c axis and slight deviations from it. A comparison of the AlN surface morphology obtained by atomic force microscopy before and after cluster processing was demonstrated. This demonstrated that the cluster ions with low energy per atom (E/N = 10 eV/atom) have a high efficiency of surface smoothing. A decrease in the intensity of the Raman peaks and an increase in their full-width after bombardment with cluster ions were found, which may be caused by a change in the physicochemical state of the surface. The optical properties, the quality of the boundaries, and the distribution map of the thickness of the functional layer of AlN were investigated by the methods of spectral and spatial resolution ellipsometry. By using the cross-sectional SEM, the direction of crystallite texturing was demonstrated. The influence of argon cluster ion bombardment on the stoichiometry of samples was analyzed by EDX spectroscopy. The results obtained demonstrate the efficiency of the cluster ion smoothing of polycrystalline thin films for microelectronics, particularly when creating surface acoustic wave resonators. [ABSTRACT FROM AUTHOR]

In order to increase the accuracy of the linearized augmented plane wave (LAPW) method, we present a new approach where the plane wave basis function is augmented by two different atomic radial components constructed at two different linearization energies corresponding to two different electron bands (or energy windows). We demonstrate that this case can be reduced to the standard treatment within the LAPW paradigm where the usual basis set is enriched by the basis functions of the tight binding type, which go to zero with zero derivative at the sphere boundary. We show that the task is closely related with the problem of extended core states which is currently solved by applying the LAPW method with local orbitals (LAPW+LO). In comparison with LAPW+LO, the number of supplemented basis functions in our approach is doubled, which opens up a new channel for the extension of the LAPW and LAPW+LO basis sets. The appearance of new supplemented basis functions absent in the LAPW+LO treatment is closely related with the existence of the ul-component in the canonical LAPW method.We discuss properties of additional tight binding basis functions and apply the extended basis set for computation of electron energy bands of lanthanum (face and body centered structures) and hexagonal close packed lattice of cadmium. We demonstrate that the new treatment gives lower total energies in comparison with both canonical LAPW and LAPW+LO, with the energy difference more pronounced for intermediate and poor LAPW basis sets. [ABSTRACT FROM AUTHOR]

The asymmetry of the detected profiles of water vapor absorption lines in a quartz tube at room temperature and pressures of 0.03–1.00 Torr was studied. The measurements were made by the method of diode laser spectroscopy with an external optical cavity. An off-axis alignment of the cavity was used for quality recording of narrow absorption line profiles. The measurements were made with different rates, 0.1–0.8 cm–1/ms, of tuning of the laser frequency with mirrors that have reflectivities of 99 and 99.98% and different directions of the laser frequency tuning. The asymmetry of the lines arises because of the time delay of the radiation inside the cavity. The results of modeling the measurements taking the filling of the cavity with laser light and its decay over time into account at the cavity output are in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

In this paper, we study a nonlinear integral equation that arises in a model of spatial logistic dynamics. The solvability of this equation is investigated by introducing special spaces of functions that are integrable up to a constant. Sufficient conditions for the biological characteristics and the parameters of the third spatial moment closure are established that guarantee the existence of the solution of the equation described above in some ball centered at zero. In addition, it is shown that this solution is unique in the considered ball and not zero. This means that, under appropriate conditions, the equilibrium state of the population of a certain species exists and does not coincide with the state of extinction. [ABSTRACT FROM AUTHOR]

We calculate electronic structure and spin susceptibility dependencies on doping within the framework of a cluster perturbation theory for strongly correlated electronic systems. The change in the susceptibility with increasing doping is qualitatively consistent with the experimental data on resonant inelastic X-ray scattering and inelastic neutron scattering, as well as with the results of the calculations within the quantum Monte Carlo method. [ABSTRACT FROM AUTHOR]

Breast cancer is one of the most diagnosed types of cancer worldwide. Volumetric ultrasound breast imaging, combined with MRI can improve lesion detection rate, reduce examination time, and improve lesion diagnosis. However, to our knowledge, there are no 3D US breast imaging systems available that facilitate 3D US – MRI image fusion. In this paper, a novel Automated Cone-based Breast Ultrasound System (ACBUS) is introduced. The system facilitates volumetric ultrasound acquisition of the breast in a prone position without deforming it by the US transducer. Quality of ACBUS images for reconstructions at different voxel sizes (0.25 and 0.50 mm isotropic) was compared to quality of the Automated Breast Volumetric Scanner (ABVS) (Siemens Ultrasound, Issaquah, WA, USA) in terms of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and resolution using a custom made phantom. The ACBUS image data were registered to MRI image data utilizing surface matching and the registration accuracy was quantified using an internal marker. The technology was also evaluated in vivo. The phantom-based quantitative analysis demonstrated that ACBUS can deliver volumetric breast images with an image quality similar to the images delivered by a currently commercially available Siemens ABVS. We demonstrate on the phantom and in vivo that ACBUS enables adequate MRI-3D US fusion. To our conclusion, ACBUS might be a suitable candidate for a second-look breast US exam, patient follow-up, and US guided biopsy planning. [ABSTRACT FROM AUTHOR]

Surface modification of polycrystalline thin films of aluminum nitride using bombardment with an cluster ion beam has been investigated. The treatment has been performed using high-energy (105 eV/atom) and low-energy (10 eV/atom) argon cluster ions. High-efficiency smoothing of the nanostructured surface in a wide range of spatial frequencies ( = 0.02–128 μm–1) at ultrasmall etching depth (<100 nm) is demonstrated by atomic force microscopy with the application of the power spectral density function of roughness. [ABSTRACT FROM AUTHOR]

The need to reparametrize the OVATION Prime (2010) empirical auroral precipitation model using the Russian polar cap index (PC index) is considered. For this purpose, the integrated auroral power of particle precipitation obtained from the Polar satellite data for the period from December 1996 to June 1998 is compared with the PC index and the Newell's coupling function. The analysis revealed that the PC index at the time delays up to 5–20 minutes correlates with the magnitude of auroral power much better (the correlation coefficient ) than the Newell's coupling function (). Thus, for the purpose of nowcasting the zone of active particle precipitation, the PC index showed much higher scores, although the predicting abilities of the Newell's coupling function for the time delays of more than 20 minutes remain the best. [ABSTRACT FROM AUTHOR]

The need to reduce operating costs of commercial uranium hexafluoride production motivates the present study. With this in mind, a variant of coolant flow reduction in the tubing of the desublimation apparatus is proposed. Mathematical calculations showed that the coolant consumption can be reduced by a factor of 2. Field experiments performed at an operating production facility have confirmed the obtained results. A combined control system has been developed to maintain the coolant flow at the minimum level and to secure the conditions of desublimation for uranium hexafluoride. The developed control system will make it possible to reduce by factor of 2 the volume of coolant consumption without loss of product quality or production volume. [ABSTRACT FROM AUTHOR]

Within the multielectron model of magnetic insulator with two different spin terms at each cation and spin crossover under high pressure we have studied dynamics of a sudden excited non equilibrium spin state. We obtain the different relaxation of the magnetization, high spin/low spin occupation numbers, and the metal-oxygen bond length for different values of the external pressure. For each pressure-temperature values stationary state agrees to the mean field phase diagrams. We found the long living oscillations of magnetization for the high spin ground state at small pressure. Close to crossover pressure the smooth relaxation is accompanied with a set of sharp strongly non linear oscillations of magnetization and HS/LS occupation numbers that are accompanied by the Franck–Condon resonances. [ABSTRACT FROM AUTHOR]

We propose a method for calculating the electronic band structure of disordered systems with strong electron correlations. Various approaches to the description of electrical conductivity of disordered systems are considered. Calculations are based on determining the one-particle Green function of the system, which is averaged over different configurations of a cluster, on the Boltzmann formalism, and the Kubo linear response theory. As the basic model, we use the Hubbard model for an A1 –xBx binary alloy. [ABSTRACT FROM AUTHOR]

The impact of mechanical milling of the mixture of Fe2O3–Li2CO3–ZnO reagents on thermal sintering of lithium–zinc ferrites of Li0.4Fe2.4Zn0.2O4 composition was studied using X-ray diffraction, dilatometric and kinetic analyses. The dilatometric analysis showed that mechanical pre-activation of the mixture of the initial reagents in a planetary mill reduces the initial shrinkage point and accelerates compaction of ferrite-pressed samples during sintering, which ultimately increases the density of the finished ferrite ceramics. The sintering of lithium–zinc ferrite from a non-milled mixture proceeds in two steps. At the first stage, the samples show linear expansion, and at ~ 720 °C, a sharp shrinkage occurs. The data obtained from milled samples indicate that shrinkage starts at lower temperatures and is in the range of 370–400 °C. This result allows simultaneous synthesis and sintering of lithium–zinc ferrite through one-stage heating of pressed samples to the sintering point. The resulting lithium–zinc ferrite ceramics exhibits high density, specific magnetization and Curie temperature. The kinetic analysis of ferrite compaction was performed, and kinetic parameters and the model to describe this process were found. [ABSTRACT FROM AUTHOR]

A theoretical model based on the relaxation equation for the density matrix has been proposed to describe the ultrafast time dynamics of magnetically ordered systems with spin crossover in an excited state under a sudden perturbation. Oscillations of the magnetization, the population of the high-spin state, and the generation of local vibrons at a transition of the system from the light-excited Franck-Condon low-spin state to the highspin ground state. [ABSTRACT FROM AUTHOR]

A method is developed for analyzing spontaneous-emission modification in cylindrically symmetric structures. A matrix method is developed for cylindrical structures. General expressions for the radiative-recombination rate are derived for an emitter placed at any point on the structure. Quantitative indicators for estimating radiative-recombination enhancement and suppression are determined; they can be considered as modal Purcell factors. An expression for the total Purcell factor is derived for an emission direction perpendicular to the symmetry axes of the medium; as well as an expression for the integral (total) Purcell factor for the emitter at the symmetry axis. [ABSTRACT FROM AUTHOR]

The process of extraction of the extracellular matrix (ECM) requires operational monitoring, since there is a risk of destruction of the main proteins of the cell matrix at non-optimal parameters of the process. Using multiphoton microscopy the structure of collagen, the integrity of the cell membrane and the content of elastin in the process of isolation of ECM from various tissues of the rat body (brain, dermis, and muscle) has been studied. It has been shown that multiphoton microscopy is an effective tool for monitoring the quality of ECM extraction. [ABSTRACT FROM AUTHOR]

We consider the change in the electronic structure of the two-band Hubbard model in the regime of strong electron correlations with spin crossover upon the passage through the crossover point depending on the crystal field growth. An abrupt semimetal–insulator–semimetal transition is detected during the passage through the spin crossover point in the absence of the spin–orbit interaction, which is accompanied by a jumpwise redistribution of the partial spectral weight between the poles of the Green function of Fermi quasiparticles. The role of the spin–orbit interaction and the change in the surface topology of surface of one-particle Green function zeros are considered. [ABSTRACT FROM AUTHOR]

Following the recent demonstration of grazing‐incidence X‐ray fluorescence (GIXRF)‐based characterization of the 3D atomic distribution of different elements and dimensional parameters of periodic nanoscale structures, this work presents a new computational scheme for the simulation of the angular‐dependent fluorescence intensities from such periodic 2D and 3D nanoscale structures. The computational scheme is based on the dynamical diffraction theory in many‐beam approximation, which allows a semi‐analytical solution to the Sherman equation to be derived in a linear‐algebraic form. The computational scheme has been used to analyze recently published GIXRF data measured on 2D Si3N4 lamellar gratings, as well as on periodically structured 3D Cr nanopillars. Both the dimensional and structural parameters of these nanostructures have been reconstructed by fitting numerical simulations to the experimental GIXRF data. Obtained results show good agreement with nominal parameters used in the manufacturing of the structures, as well as with reconstructed parameters based on the previously published finite‐element‐method simulations, in the case of the Si3N4 grating. [ABSTRACT FROM AUTHOR]

We analyze the influence of cooperative effects on the magnetic properties and spin crossover between the high-spin (HS) term S = 5/2 and low-spin (LS) term S = 1/2 in Mott–Hubbard dielectrics with 3d5 ions under high pressures. Two cooperation mechanisms (superexchange interaction and effective interaction via the elastic system) are considered. The sign of the exchange interaction changes because of the crossover from the antiferromagnetic in the HS state to the ferromagnetic in the LS state. In view of the large difference between the ionic radii of the HS and LS states, the systems with spin crossover acquire an additional strong coupling via the elastic system. Using the Hubbard operator representation and considering the electronic states of the two terms simultaneously, we obtain the effective Hamiltonian with allowance for the cooperative effects. The magnetic phase diagram and the spin crossover are investigated in the mean field approximation. It is shown that the inclusion of cooperative effects at low temperatures leads to a first-order phase transition between the antiferromagnetic HS state and the ferromagnetic LS state. At higher temperatures, more complicated sequences of phase transitions are possible upon an increase in pressure, including the HS paramagnet–HS antiferromagnet–LS paramagnet and HS antiferromagnet–LS paramagnet–LS ferromagnet transitions. [ABSTRACT FROM AUTHOR]