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The article shows that the crisis phenomena taking place in the world have an impact on many socio-economic processes. The scale of these negative consequences affected not only the local markets of countries, but also made significant adjustments to the existing economic relations in supply chains and their structure on a global scale. The analysis of the current situation is based on reports and statistics from the European Union and the World Bank. An assessment of the sectors of the EU transport sector and the change in their share of participation in trade and economic relations of the EU member states during the COVID-19 pandemic was made. The main directions for overcoming the crisis were offered. [ABSTRACT FROM AUTHOR]

This study is about the influence of supply chain business strategy, logistics performance and information technology performance on the competitiveness of the medical device industry. The results obtained are that the supply chain business strategy has a direct effect on logistics performance, information technology performance on the supply chain competitiveness of the medical device industry during the COVID-19 period in Indonesia. Data was obtained by distributing questionnaires to 248 respondents as samples. Analysed the data using a structural equation modelling (SEM) analysis tool. The findings show that business strategy has a positive and significant effect on logistics performance, information technology performance on the competitiveness of medical devices in Indonesia. Based on these findings, to improve and maintain competitiveness are investment, availability, quality of hardware and software infrastructure in information technology, customer satisfaction, good relations with suppliers and reacting quickly and appropriately in all logistics and supply chain activities to excel in front of competitor. Originality is the competitiveness of the supply chain is determined based on the assessment of experts in the supply chain. Further research can be expanded to include indicators such as ROA (return on assets), ROI (return on investment) and market share. [ABSTRACT FROM AUTHOR]

A simple mathematical model of UN, U2N3, and UN2 crystals is used for reconstructing the pair potentials of interaction of the nearest neighbors and subsequent molecular dynamics simulation. The corresponding parameters of the U−N potential in U2N3 and UN2 crystals are obtained from the experimental values of the lattice constant and the bulk moduli of UN, U2N3, UN2 at room temperature. The linear expansion coefficients of U2N3 and UN2 crystals, as well as the U2N3 bulk modulus are estimated within the harmonic approximation. The dependences of the U2N3 and UN2 lattice constants on temperature are calculated by the molecular dynamics method. [ABSTRACT FROM AUTHOR]

Molecular dynamic simulation of helium diffusion within a ring dislocation inside a stoichiometric UO2 nanocrystal was carried out. Two different sets interaction potentials were used. One of the sets was characterized by a significantly stronger binding of helium to the crystal lattice. Temperature dependencies of the diffusion coefficient along the dislocation line were obtained. It was shown that the strengthening in the binding of helium led both to a decrease in the diffusion coefficient of the atom and to an increase in the temperatures at which the model dislocation was annealed. [ABSTRACT FROM AUTHOR]

Using a global optimization method, the parameters of a pair potential of the interaction of thorium and oxygen ions in ThO2 are fitted, which are compatible with the potential set MOX-07 previously proposed for UO2 and PuO2 crystals. The potential is expressed in the form U(R) = exp(X–Y•R) eV, and the optimal parameter values are X = 8.073687, Y = 3.349 Å−1. Using these parameter values, the potential reproduces the lattice constant of the ThO2 crystal in the entire temperature range up to melting, and quantitatively describes the high-temperature peak in the heat capacity that is associated with the superionic transition. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation of helium diffusion in solid CaF2, SrF2, and BaF2 was carried out using the empirical pair potentials reproducing the experimental strong binding of helium to cations in these crystals. The model diffusion coefficients and activation energies are determined. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation of small PuO2 nanocrystals consisting of 105−174 ions at the temperature T = 1700 K was carried out. The structures of the vertices and the surface created during thermal disordering and subsequent relaxation of these nanocrystals were studied. The vertices formed by two adjacent plutonium cations, as well as truncated vertices of the regular octahedron that consisted of 4 plutonium cations lying in the same plane (100), were most frequently encountered. Sharp vertices of the regular octahedron ending in one cation usually corresponded to metastable states of the crystal lattice or to crystallites with an increased specific energy. According to the results, sequences of the “magic numbers” were proposed to specify the sizes of plutonium dioxide nanocrystals characterized by the most stable surface. [ABSTRACT FROM AUTHOR]

Molecular dynamic simulation of helium diffusion within a ring dislocation inside stoichiometric UO2 nanocrystal was carried out. During the computational experiments (2.7 ns) in the temperature range from 525 to 1000 K, the dislocation was stable and the helium atom was contained inside the dislocation core. The magnitudes of the diffusion coefficient varied from 4.1·10–6 to 6.6·10–5 cm²/s. The diffusion process could be characterized by the constant activation energy ED = (0.25 ± 0.05) eV. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation of the melting of UO2 nanocrystals of the optimal truncated octahedron shape in the size range from 4317 to 381174 ions was carried out. The dependence of the melting temperature of the nanocrystals on the size was obtained at the time of evolution of the model system up to 150 ns. This dependence was characterized by nonlinearity caused by a change in the melting mechanism corresponding to the transition from larger nanocrystals to smaller ones. The nanocrystals containing more than 20 000 ions undergo the phase transition as a result of the formation of the surface melt on a single (111) face, which caused the irreversible propagation of the melt into the bulk. Smaller crystallites could melt at temperatures below the crystallization temperature of the (111) face, provided that two adjacent faces melt simultaneously due to the thermal activation. The difference in melting temperatures of the largest and smallestmodel crystals was 320K, which corresponds to the experimental estimates. [ABSTRACT FROM AUTHOR]

The process of mass transfer in (U,Pu)O2 nanocrystals is studied using the molecular dynamics simulation. The dependence of the vacancy concentration on temperature was estimated by calculating the time of presence of the vacancies in the crystallite bulk. The effective formation energy of vacancies obtained from this dependence was (10 ± 2) eV. Within the limits of error, this energy coincides with the formation energy of the Schottky defect calculated by the lattice static method, and also with the effective energy characterizing the frequency of vacancy formation. [ABSTRACT FROM AUTHOR]

The work is devoted to the analysis of Russian-language texts using the random walk model. The frequencies and order of the vowel letters are compared to the migration of quasiparticles that is characterized by the diffusion coefficient and the deviation of the mean squared displacement of the quasiparticles from the Einstein relation. These parameters are determined for six subcorpora of texts, differing in functional styles. The dispersion of the parameters inside each of the subcorpora is described by the gamma distribution. The distributions for the differing subcorpora are shown to have statistically significant difference. It is found, particularly, that religious and poetic texts stand out in separate groups. On the basis of the obtained data, features of the internal structure of texts, defined by the functional style, are discussed. [ABSTRACT FROM AUTHOR]

Molecular dynamic simulation of krypton bulk diffusion in stoichiometric UO2 nanocrystals with free surface is carried out. The values of the diffusion coefficient in the temperature range from 1000 K to 3000 K are obtained. The magnitudes of the diffusion coefficient varied from 3.10-8 to 1.10-4 cm²/s. It is shown that the temperature dependence of the diffusion coefficient could be characterized by a constant activation energy ED = (1.00 - 0.03) eV. The predominant mechanism of diffusion consisted in the movement of the atom by the interstitial positions via the sites of the anion sublattice, accompanied by the displacement of oxygen ions to the interstitial positions. [ABSTRACT FROM AUTHOR]

This article presents the methodology for calculating the energy release field using the GEFEST-800 software and hardware complex; the aim is to optimize the energy release field. [ABSTRACT FROM AUTHOR]

A formal approach to text analysis is suggested that is based on the random walk model. The frequencies and reciprocal positions of the vowel letters are matched up by a process of quasi-particle migration. Statistically significant difference in the migration parameters for the texts of different functional styles is found. Thus, a possibility of classification of texts using the suggested method is demonstrated. Five groups of the texts are singled out that can be distinguished from one another by the parameters of the quasi-particle migration process. [ABSTRACT FROM AUTHOR]

The interaction of xenon clusters with the collision cascades in the PuO2 crystals is investigated using the molecular dynamics simulation and the approximation of the pair interaction potentials. The potentials of interaction of Xe atoms with the surrounding particles in the crystal lattice are suggested, that are valid in the range of high collision energies. The cascades created by the recoil 235U ions formed as the plutonium α-decay product are considered and the influence of such cascades on the structure of the xenon clusters is analyzed. It is shown, that the cascade-cluster interaction leads to release of the xenon atoms from the clusters and their subsequent re-solution in the crystal bulk. [ABSTRACT FROM AUTHOR]

The process of release of PuO2 molecules and clusters from the surface of PuO2 crystals caused by the α-decay collision cascades is studied using the molecular dynamics simulation. The amount of material emitted this way is calculated depending on the depth of the cascade initialization with respect to the surface. The estimated rate of the release (0.85 atoms/decay for a spherical 239PuO2 particle of the radius of 1 μm) is in good agreement with experimental data (0.72 atoms/decay for the particles of the same size). [ABSTRACT FROM AUTHOR]

A model of uranium hexafluoride is suggested that is based on the empirical pair potentials of U-U, F-F, U-F used for both intra- and intermolecular interactions. The potentials for this model are obtained from the lattice parameters and the thermal expansion coefficient of UF6 crystal using the molecular dynamics simulation under the periodic boundary conditions with constant volume and temperature. Within the framework of the model, the thermal expansion and sublimation of crystalline UF6 are investigated. A set of potential parameters is identified that provides satisfactory simulation of both UF6 crystal and the dependence of the UF6 saturated vapor pressure on temperature. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation of the self-diffusion of thorium cations in ThO2 nanocrystals with a free surface is conducted. It is shown that a vacancy in the bulk of a crystal initiates a complex collective movement of cations, in which the interstitial positions surrounding the vacancy are involved. The diffusion coefficients of cations in the temperature range are calculated. The effective activation energy of diffusion is ED = (7.6 ± 0.7) eV. [ABSTRACT FROM AUTHOR]

Two alternative sets of interaction potentials of a xenon atom with the ionic environment in the plutonium dioxide crystal are compared with respect to the simulation of high-energy processes. It is shown that an increase in the hardness of the potentials at the interaction energies near and above 1000 eV significantly increases the fraction of energy transferred to xenon bubbles by collision cascades, also lowering the threshold energy of displacement of the xenon atom. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation of sintering of two octahedral uranium dioxide nanocrystals contacting in the vertex region is carried out. Two main stages of the sintering process are observed. At the beginning of the simulation, the neck between the crystallites is formed due to the mutual attraction of the adjacent (111) faces. Further increase in the neck thickness occurs due to transport of the material from the surface of the crystallites in a much slower diffusion process. The estimate of the activation energy of this process is in the range from 11 to 14 eV. [ABSTRACT FROM AUTHOR]

The elastic and thermal properties of TbH2 compound were studied using the density functional theory (DFT) for temperature ranges from 0 to 800 K within the local density approximation (LDA) pseudopotential. The elastic constants and mechanical properties such as bulk modulus B, Young's modulus E, shear modulus GH, Poisson's ratio σ, Debye temperature (ϴD), and sound velocities (vm) of TbH2 compound were investigated. Moreover, the first principles density functional perturbation theory (DFPT) as implemented in the quasi-harmonic approximation (QHA) was used for the calculation of the thermal properties like vibrational energy ΔF, entropy S, internal energy ΔE and constant-volume specific heat CV of the TbH2. The obtained B/G ratio is 2.51, which reveals the good ductility of the TbH2 compound. [ABSTRACT FROM AUTHOR]

We have employed the density functional theory (DFT) to study structural, electronic and vibrational properties of H-passivated Si/Ge core-shell nanowire. The dynamical stability of the NW is analyzed by formation energy and phonon dispersion curve. We have observed that there is a decrease in band gap in the core/shell as compared to its corresponding pure nanowires, which may be due to the strain induced at Ge-shell in presence of Si-core. The Si/Ge nanowire shows direct band gap of 1.47 eV. The stable structure with direct band gap nanowire could show potential applications in the field of the sensors, bipolar and FET transistor. [ABSTRACT FROM AUTHOR]

We have investigated two-dimensional (2D) monolayer structures composed of p-group binary elements. Here, we have focused on the dynamic stability and bandgap tuning of novel boron (B) doped carbon phosphide (CP) monolayer by implementing external perpendicular electric fields to the layer using ab initio method based on density functionals theory (DFT). First, we have optimized boron doped CP monolayer and analyzed direct band gap 0.65 eV at M-point. With increasing of the applied electric fields for ±0.5 V/Å to ±1.5 V/Å; the bandgap continuously decreases up to metallic nature. The low effective mass is showing the high carrier mobility. The changing to the atomic distance and corresponding charges could be responsible to the semiconductor to metal behavior. This study is relevant for the fabrication of novel electronic and photonic devices. [ABSTRACT FROM AUTHOR]

A density functional theory (DFT) based computation was conducted to study the electronic band structure, electron density of states (DOS) and partial DOS of ZnO/CdX core/shell nanowires (NWs), where X= S, Se, Te. The band structures calculations show a direct band gap of approximately 1.555 eV, 1.167 eV and 0.833 eV for ZnO/CdS, ZnO/CdSe and ZnO/CdTe, respectively at Γ-point, using generalized gradient approximation (GGA). The TDOS and PDOS calculations predict that a sharp peak is obtained at -9 eV below the Fermi level, in the valence band (VB) due to the possible hybridization between Zn-s, O-p and X-p orbitals. Also, it was observed that the contributions to the total DOS at the conduction band (CB) are mainly dominated by Zn-s and Cd-s orbitals, hinting at possible strong hybridization between them. Also, the low band gaps of ZnO/CdSe and ZnO/CdTe NWs predict the opacity of these NWs at room temperatures while the relatively high band gap of ZnO/CdS NW could suggest their use in fabrication of high operating voltage devices. Our conjecture hint at the applications of these NWs in devices where selective absorbance is a desired characteristic. [ABSTRACT FROM AUTHOR]

Atomistic understanding of the interaction between defects and active surface of the sensor is necessary for the developing devices detecting bio-and gas mixtures. We performed first principles computer simulations of the carbon dioxide (CO2) molecule adsorption on a ZnO surface in various configurations and location on the surface. It is shown that the tridentate configuration is the most energetically favorable, the binding energy of the molecule weakly depends on the surface coverage. The presence of intrinsic defects on the surface, such as an oxygen vacancy, leads to a small reduction of the binding energy. The observed data from the NEXAFS experiment and hypothetical formation of a new compound H2CO on the surface are discussed in the light of our calculations. [ABSTRACT FROM AUTHOR]

A technique is proposed for the recovery of pair potentials for the interaction of intrinsic ions in crystals. Using this approach, a unified set of empirical pair interaction potentials for simulation of uranium carbide crystals UnCm in the ionic approximation by the method of molecular dynamics is obtained. The potential parameters are determined from the experimental values of the lattice constant and the UC, U2C3, UC2 bulk compression moduli, as well as the linear expansion coefficient of UC crystal at room temperature. The temperature dependences of the lattice constants and the coefficients of linear expansion of the model uranium carbide nanocrystals are calculated using the suggested potentials. The dependence of the melting temperature of the model nanocrystals on composition is also discussed. [ABSTRACT FROM AUTHOR]

In this work, we have studied nanoclusters of thorium (Thn) (n=2-6), using first principles calculation by density functional theory. Out of these nanoclusters, the most stable isomer of Th is found to have square bipyramidal structure (Th6(b)). We have also calculated HOMO-LUMO gap (HLG) and chemical hardness of these nanoclusters, which indicates that these atomic clusters are soften. HLG of most stable nanoclusters of Th first increases from 0.29 eV (n=2) to 0.72 eV (n=4) and then decreases to 0.27 eV (n=6). Further, absorption spectra of these nanoclusters show absorption mainly in infrared (IR) and visible region (UV). [ABSTRACT FROM AUTHOR]

Thorium dioxide (ThO2) is most commonly used nuclear fuel with UO2 and PuO2 in thermal breeder nuclear reactor. ThO2 has fluorite type structure at normal pressure, but at higher pressure it shows transition from fluorite type structure to cotunnite type structure. We have considered cotunnite type ThO2 structure to study the electronic and optical properties using first principles method. This high pressured ThO2 structure shows direct band gap of 3.43 eV. Density of states shows major contribution of 2p orbital in valence band while conduction band is dominated by 5f orbital near the Fermi energy level. Static dielectric constant and refractive index are found to be 2.86 and 1.67. Absorption spectra show absorption in UV region with a sharp peak at 5.67 eV. [ABSTRACT FROM AUTHOR]

In the present work, we have presented core/shell geometry of GeSn NW, where Ge shell is built around very thin Sn cores. We have studied phonon dispersive curve and its binding energy for dynamical and thermodynamic stability of the NW. We have observed direct bad gap of 0.68 eV for the Sn/Ge NW. The valance band is contributed by Ge atom, while the conduction band is contributed by Sn atom near the Fermi level. The direct band gap in Sn/Ge NW indicates its potential application in Si-based light emitting diode as future light energy source. [ABSTRACT FROM AUTHOR]