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The objective of the study was to study the perceptions of student teachers and educators of an educational cluster as a tool for improving the professional competence of future educators, and to identify the cluster-related tools to be used to improve the professional competence of future educators. The project evaluation checklist for experts, a questionnaire for participants in the experiment, a semi-structured interview questionnaire to conduct with focus group respondents were used for collecting data. Data were processed using content analysis technique and SPSS Statistics v24 package. The study is quantitative, based on subjective evaluations of study participants and representatives of educational clusters, and does not aim at evaluating students' achievements. Two simulation models of the educational cluster ("Cluster Educational Initiative" and "Cluster of Educational Opportunities for Educators 2.0") and four educational activities for educators (discussion "Agglomeration of Subjects, Educational Institutions: Realities and Prospects"; online conference "Ukraine-Brussels -- Sharing Experience in Education"; an educational tour to Finland for teachers, parents and managers in the field of education; the exchange of four teachers from two schools) was a key result of this study. It has been found that the creation of clusters for improving the professional competence of future educators and their professional advancement is now part of national education policy in Ukraine and in the world. The tools of this form of organization of educational activity are competence-oriented and aimed at deepening professional experience, development of competences of realization of life-long education, creation of own public image.

The deformation mechanism of body-centered cubic (bcc) nanocrystalline tantalum with grain sizes of 10–30 nm is investigated by nanoindentation, scanning electron microscopy and high-resolution transmission electron microscopy. In a deviation from molecular dynamics simulations and existing experimental observations on other bcc nanocrystalline metals, the plastic deformation of nanocrystalline Ta during nanoindentation is controlled by deformation twinning. The observation of multiple twin intersections suggests that the physical mechanism of deformation twinning in bcc nanocrystalline materials is different from that in face-centered cubic (fcc) nanocrystalline metals.

Review is presented on an optical technique for fabricating in a single step three dimensional (3D) nanostructures with diverse structural layouts. These structures illustrate its capabilities and possible areas of use in technologies.

Inertial confinement fusion (ICF) power, in either pure fusion or fission-fusion hybrid reactors, is a possible solution for future world's energy demands. Formation of uniform layers of a condensed hydrogen fuel in ICF targets has been a long standing materials physics challenge. Here, we review the progress in this field. After a brief discussion of the major ICF target designs and the basic properties of condensed hydrogens, we review both liquid and solid layering methods, physical mechanisms causing layer nonuniformity, growth of hydrogen single crystals, attempts to prepare amorphous and nanostructured hydrogens, and mechanical deformation behavior. Emphasis is given to current challenges defining future research areas in the field of condensed hydrogens for fusion energy applications. [ABSTRACT FROM AUTHOR]

Current baseline designs of ignitable inertial confinement fusion targets require smooth layers of solid hydrogen held at a few degrees below the melting temperature on the inner surface of thin-walled spherical capsules. The initially smooth solid/vapor interface of a presumably single crystalline (hexagonal closed packed) hydrogen layer grown from melt develops undesirable roughness on cooling. We attribute such roughness to plastic deformation relieving thermal-contraction-induced elastic stresses. In particular, we identify two major contributors to roughness: surface bands of the basal slip systems and thermal grooves formed on deformation-produced low-angle grain boundaries. These findings have important implications for designing strategies aimed at controlling uniformity of the hydrogen fuel layer in fusion targets. [ABSTRACT FROM AUTHOR]

The electronic structure of ultralow density nanoporous chromia monoliths (aerogels) is studied by soft x-ray absorption near-edge structure (XANES) spectroscopy. These aerogels are prepared by the epoxide sol-gel method. High-resolution O K edge and Cr L2,3 edge XANES spectra of aerogels (before and after thermal annealing at 550 °C) are compared with spectra of microcrystalline α-Cr2O3 and orthorhombic CrO3 powders, α-Cr2O3 (0001) and (1102) single crystals, and an unrelaxed amorphous phase of full-density Cr2O3. Spectra are interpreted based on the results of crystal-field multiplet calculations (for Cr L2,3 edge) and ab initio spin-polarized density functional theory calculations with and without a Hubbard-type on-site Coulomb repulsion (for O K edge). Results show that the electronic structure of as-prepared aerogels, with a large fraction of undercoordinated surface atoms, is significantly different from that of bulk α-Cr2O3, CrO3, or amorphous Cr2O3. Thermal treatment transforms the as-prepared amorphous aerogel into α-Cr2O3 nanopowder. [ABSTRACT FROM AUTHOR]

The plastic deformation of nanoporous Au under compressive stress was studied by depth-sensing nanoindentation combined with scanning electron microscope characterization. The nanoporous Au investigated in the current study exhibits a relative density of 42%, and a spongelike morphology of interconnecting ligaments on a length scale of ∼100 nm. The material is polycrystalline with a grain size on the order of 10–60 nm. Microstructural characterization of residual indentation impressions reveals a localized densification via ductile (plastic) deformation under compressive stress and demonstrates the ductile behavior of Au ligaments. A mean hardness of 145(±11) MPa and a Young’s modulus of 11.1(±0.9) GPa was obtained from the analysis of the load-displacement curves. The hardness of investigated np-Au is ∼10 times higher than the hardness predicted by scaling laws of open-cell foams thus potentially opening a door to a class of high yield strength—low-density materials. [ABSTRACT FROM AUTHOR]

Spectra of positively charged secondary ions from thermally grown SiO[sub 2] films were recorded in a time-of-flight secondary ion mass spectrometry scheme. Ablation of cluster ions was induced by the impact of slow (4 keV/u) Au[sup 69+] projectiles. The intensities of Si[sub x]O[sub y]H[sub z][sup +], (x=1-22, y=1-44, z=0-7) clusters are found to depend sensitively on the oxygen to silicon ratio and also on the hydrogen content. We find that oxygen rich clusters, y=2x+1, and, in one case, y=2x+2, can be stabilized by the incorporation of two additional hydrogen atoms in the cluster. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the optical damage mechanisms in hafnia and silica thin films using pairs of subnanosecond laser pulses with variable time delay. Experimental procedures; Measurements and discussion; Conclusions.

The dissociative adsorption of C1–C4 alkanes on Ir(110)–(1×2) was investigated using supersonic molecular beam techniques. Three regimes of reactivity were observed. At incident kinetic energies less than 100 kJ/mol the dissociative adsorption probability for propane and butane increased to about 0.6 with both decreasing surface temperature and decreasing translational energy of the incident molecule suggesting that activation occurred via trapping of the alkane on the surface. At kinetic energies below 110 kJ/mol for butane, 90 kJ/mol for propane, 60 kJ/mol for ethane, 40 kJ/mol for methane, and at elevated surface temperatures the reaction probabilities for alkanes were independent of surface temperature and translational energy, but increased significantly with the molecular weight or carbon chain length of the incident alkane. This behavior indicates an unactivated reaction channel for each species except methane. At kinetic energies above 110 kJ/mol for butane, 90 kJ/mol for propane, 60 kJ/mol for ethane, and 40 kJ/mol for methane the initial dissociative sticking probability increased with increasing translational energy and was independent of surface temperature, indicating direct translational activation of the incident alkane. The translational energy required to activate the incident alkane via this channel increased with carbon number or molecular weight, indicative of energy transfer processes that dissipate energy in the reactive collision. The dissipative transfer of translational energy out of the reactive channel via a hard cube collision with the surface accounts qualitatively for the increase in the apparent activation barrier with increasing molecular weight in this activated channel. [ABSTRACT FROM AUTHOR]

The interaction of a collisionless beam of thermal C60 nanoclusters with a silicon dioxide surface has been investigated with modulated molecular beam-mass spectroscopic techniques. Analysis of the amplitude and phase lag of the desorbed C60 shows the interaction mechanism to involve the elementary steps of sticking, desorption, and long-range surface diffusion. Surface diffusion coefficients determined in this measurement indicate that surface C60 nanoclusters approach two-dimensional gas-like behavior. The sticking probability of C60 clusters on SiO2 is determined to be unity. The best fit desorption rate constant kd for C60 from SiO2 is 5×1010 exp(-23 kcal/mol/RT) in agreement with previous temperature programmed desorption experiments. The efficiencies of electron impact ionization of C60 to C60+ and C60++ is measured for electron energies from 10 to 105 eV for neutrals at 875 K. [ABSTRACT FROM AUTHOR]

Discusses the space charge effects and self-acceleration of intense surface photoemission. Production of copious electron emission during ultraviolet laser irradiation; Acceleration of electrons by the time-dependent fields; Role of the steady-state fields in returning most of the emitted electrons to the surface.