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The study explores the impact of surface orientation and tilt on incident solar irradiation. It was conducted in M'Sila, an Algerian province, from February to June. A number of experiments were carried out using an experimental setup consisting of a heliometer and a slant changer, which allowed for the variation of the tilt angle. Nineteen tilt angles ranging from 0° to 90° were investigated for the four main directions: North, South, East, and West. The obtained outcomes were statistically analyzed. At east and south orientations, incident solar irradiance rose as a function of tilt angle, reaching a maximum at the optimal angle, and then gradually decreased. Generally, the incident solar irradiance decreased as the tilt angle increased in the case of west and north orientations. The tilt angle of the exposed surface as well as the sun's elevation in the sky affected the amount of intercepted energy significantly at each orientation (p<0.05). When the sun was low in the sky, the south orientation was most preferred for an inclination greater than or equal to 25°. The north-facing surfaces with steep slopes (β ≥ 55°) received the least amount of solar radiation. These results hold great importance, particularly in the building sector, as they can be utilized to achieve energy saving. [ABSTRACT FROM AUTHOR]

Understanding the interaction between hydrogen (H) and helium-vacancy (He-V) complexes in tungsten (W) is important for the development of plasma-facing materials in fusion reactors. H trapping by HexVy complexes in bulk W, as well as the H solution behavior and H trapping by HexV complexes near W(100), W(111), and W(110) surfaces, has been investigated by first-principles computer simulations using density function theory. The results show that the sequential H binding energies to HexV complexes in bulk W decrease with the increasing number of H and He. For the HexV2 complexes in bulk W, H prefers to trap at interstitial sites near the junction of the di-vacancy, where the H can minimize the isosurface of optimal charge density. The most stable interstitial sites for H below W surfaces are dependent on the surface orientation. Our calculations indicate that H atoms tend to prefer a depth of 0.3 nm below the W(100) and W(111) surfaces due to the surface reconstruction. The binding energy of H to a HeV complex near W surfaces has the most significant orientation dependence below the W(111) surface, followed by the W(100) and W(110) surfaces. Compared with the bulk value, the largest difference in the average binding energy of H to the stable HexV complexes at the three W surfaces is about 0.2 eV. Furthermore, the effect of surfaces on the H binding energy to HexV complexes can be ignored for depths greater than 0.65 nm. [ABSTRACT FROM AUTHOR]

Density function theory calculations have been performed to study the stability of small helium-vacancy (He-V) complexes near tungsten (W) surfaces of different orientations. The results show that the stability of vacancies and He-V complexes near W surfaces depends on surface orientation. However, as the depth below the surface increased beyond about 0.65–0.8 nm, the stability of He-V complexes is similar to the bulk. The formation energies of single vacancies and di-vacancies at depths less than 0.2 nm below the W(110) surface are higher than for W(100) or W(111) surfaces, but have lower energies at depths between 0.2 and 0.65 nm. The formation energies of He-V complexes below W surfaces are sensitive to the geometric orientation of the He and vacancy, especially below the W(111) surface. Within about 0.2 nm of the top layer of the three W surfaces, neither a vacancy nor a di-vacancy can trap He. Because of the lower formation energy of He-V complexes and higher He binding energy to vacancies below the W(110) surface, the He desorption from the W(110) surface is less likely to occur than from the W(100) and W(111) surfaces. Our results provide fundamental insight into the differences in surface morphology changes observed in single W crystals with different surface orientations under He plasma exposure. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of the friction plate hardness and surface orientation of a friction plate on the angle and coefficient of static friction of cereal kernels. The angle of static friction of kernels representing four major cereal species was measured on six friction plates with different hardness. The friction plates were placed in position where their surface orientation was perpendicular or parallel relative to their inclination tilt. The experimental material comprised the so-called flat seed units, where each unit consisted of three spaced kernels. The angle of static friction of every flat seed unit was measured with a dedicated device in three replications, and average values of that angle were calculated. The kernels' angle of static friction varied considerably from 13° to 33° within the analyzed range of changes in the surface characteristics of friction plates. The average angle of static friction was influenced mainly by the surface orientation of the friction plate that came into contact with cereal kernels. The angle of static friction was 17.5% to 56.5% higher when the friction plate had perpendicular rather than parallel surface orientation. The frictional properties of kernels were less influenced by plate hardness, and clear relationships were not observed in this respect. The kernels' coefficient of static friction remained fairly constant within the analyzed range of plate hardness values, and it was estimated at 0.4 on plates with a perpendicular surface orientation and at 0.3 on plates with a parallel surface orientation. [ABSTRACT FROM AUTHOR]

CeO 2 nanocubes with (100) surface orientation are successfully synthesized and found to facilitate the sinterability of CeO 2 material. The CeO 2 nanocubes show a much-improved sinterability relative to CeO 2 nanoparticles prepared by the conventional citric-nitrate method. The nanocubes can be successfully sintered at a relatively low temperature of 1200 °C without using any sintering aids. In contrast, a pellet using conventional CeO 2 nano-powder obtained from the conventional citric-nitrate method can be densified only after sintering at 1400 °C, which is 200 °C higher than that for the CeO 2 nanocube sintering, although the starting particle size of both CeO 2 samples is similar. Density functional theory indicates that the surface energy of the (100) plane is significantly higher than that of the (111) plane, which is the more typical surface presentation of conventional CeO 2 particles. This high surface energy allows fast growth of the CeO 2 nanocubes during sintering, contributing to their improved sinterability. [ABSTRACT FROM AUTHOR]

Highlights • CHF (Critical Heat Flux) decreases with the heated surface orientation. • Vapor behaviors prior to CHF can be characterized into three regions. • Bubbles generated from the vertical surface were drifted upward freely. • Bubbles generated from the heater facing downward were forced upward. • Bubbles generated from the horizontal facing downward were remained on the heated surface. Abstract A visualization study on boiling phenomena at various surface orientations was conducted to investigate the bubble behaviors and the critical heat flux (CHF) mechanism. The vapor behavior observed in this study indicates that the pool boiling can be categorized into three regions: upward facing (0° ≤ θ < 90°), vertical and near-downward facing (90° ≤ θ ≤ 165°), and downward facing (165° < θ ≤ 180°). In the upward-facing region, the vapor was generated and detached easily in the vertical direction of the heated surface. In the vertical and near-downward facing region, the vapor grew and drifted upward the surface in a wavy shape owing to the vapor flow. When the heater faced downward (165° < θ ≤ 180°), the vapor was trapped and blanketed the entire heated surface. According to the vapor behaviors at various inclination angles, the CHF decreased with the increase of the surface orientation from horizontal facing upward to downward. The vapor film thickness decreased as the surface orientation increased from 0° to 180°. The vapor velocity affected the distance between the two wavelength peaks of the vapor. Faster vapor flow yielded a shorter wavelength. Additionally, the CHF location was affected by the surface orientation owing to the vapor behavior. These results indicate that the surface orientation significantly affects the vapor behavior, CHF, CHF location, vapor velocity, wavelength, and maximum and minimum vapor thicknesses on a printed circuit board in a saturated water pool. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Patterned arrays of nanoholes and nanorings were prepared using colloidal lithography combined with steps of solution immersion and vapor deposition of organosilanes. Samples prepared with colloidal lithography exhibit millions of reproducible test structures with a periodic arrangement throughout areas of the surface according to the dimensions and spacing of the particle mask. Views of the size and morphology of nanopatterns obtained with atomic force microscopy (AFM) can provide information of progressive steps of chemical reactions as nanostructures are grown within spatially confined areas surrounded by a resist film. A surface mask of colloidal latex or silica spheres was used to protect discrete areas of a Si(111) substrate from the deposition of organosilanes. When the mask was removed, the uncovered areas of the surface revealed regularly-shaped, small sites of uncovered substrate available for further reaction steps to build hierarchical surface structures. Nanostructures of zinc phthalocyanines (ZnPcs) were constructed using amine-terminated nanopatterns as sites for binding. Spatial selectivity was achieved for directing the attachment of ZnPcs to the surface using resist films of 2-methoxy(polyethyleneoxy)propyl]trichlorosilane (PEO-silane) and also with octadecyltrimethoxysilane (OTMS). The molecule chosen as a linker was (3-aminopropyl)triethoxysilane (APTES) which presents an amine group at the interface. In general, phthalocyanine molecules tend to bind in a coplanar orientation by physisorption to the surface and can stack together through pi-pi interactions between adjacent macrocycles. However, the nature of the substituents will also influence whether the molecules assemble on surfaces in a side-on orientation or with the macrocycle oriented in a coplanar arrangement. Hydroxyl and isothiocyanate pendant groups were attached to the macrocycles of ZnPcs chosen for this study, to investigate conformational differences when attached to APTES nanopatterns. The size and morphology of nanostructures was visualized and sensitively measured with tapping-mode AFM. The elastic response of samples patterned with ZnPc was mapped with force modulation AFM. Changes in the height of nanostructures indicate whether the macrocycles are oriented upright or parallel to the surface plane, or if multilayers were formed. [ABSTRACT FROM AUTHOR]

Abstract The surface orientation of crystals has an influence on various material properties, like the oxidation. A method was developed to correlate the oxidation rate for individual single crystal grains with their surface orientation. The surface orientation of many grains of polycrystalline, recrystallized tungsten samples was determined using electron backscatter diffraction. Subsequently, the samples were oxidized in a thermobalance, measuring the time dependent weight increase. The grain dependent oxidation rates were determined by measuring the thickness of the oxide layer for many individual grains with confocal laser scanning microscopy and the scanning electron microscopy on focus ion beam prepared cross-sections. In the temperature range of 720 K to 870 K, tungsten grains with {100} surface orientation have the highest oxidation rate, which is two times higher than the lowest oxidation rate. The lowest oxidation rate belongs to the {111} surfaces orientation, while the {110} surfaces orientation has an intermediated rate. The derived oxidation rates are consistent with gravimetric measurements. They follow an Arrhenius behavior with an activation energy of 190 kJ/mol. Highlights • Method to measure and evaluate orientation of many single crystal grains • Determine the fraction of the oxide layer above and below the original surface level • The oxidation rate vary by a factor of two in temperature range 720 to 870 K [ABSTRACT FROM AUTHOR]

A metal–interlayer–semiconductor (MIS) structure that is realized by inserting an ultrathin interlayer between a contact metal and a semiconductor has been investigated recently as a low-resistance non-alloyed contact structure. However, a comprehensive and systematical investigation of Schottky barrier height (SBH) modulation through the insertion of an interlayer depending on the contact surface orientation has not been conducted despite its importance for its use in multi-gate transistors. Therefore, in this work, the SBH modulation of the MIS contact structure for different contact surface orientations is systematically investigated, and a comprehensive analysis platform of the MIS contact structure is suggested. Two factors, (1) alleviation of Fermi-level pinning due to metal-induced gap states and interface states and (2) formation of the interface dipole, contribute to the SBH modulation in the MIS contact structure. Their contributions depending on the contact surface orientation are evaluated through a comparison of the contact structures on (100)- and (110)-oriented germanium (Ge). These factors and how they should be considered for a certain contact surface in Ge-channel multi-gate transistors are investigated. The investigation and the proposed analysis platform will contribute to the design of high-performance non-alloyed contact schemes for next-generation multi-gate transistors. [ABSTRACT FROM AUTHOR]

Highlights • Pt3Al intermetallic alloy supports near-surface discrete breathers (DB). • Properies of DB depend on surface orientation and termination. • DB can localize energy about 1 eV. • DB can help to overcome potential barriers for structure transformations. Abstract It is known that defect-free crystals can support spatially localized, large amplitude vibrational modes with frequencies outside the linear phonon spectrum. Such excitations are called discrete breathers (DB) or intrinsic localized modes. So far, for 3D crystals DB were considered only in the bulk. In the present molecular dynamics study, for the first time, we demonstrate that DB can be excited at the low Miller indices surfaces of the Pt 3 Al intermetallic alloy. It is shown that properties of the DB depend essentially on the surface orientation and termination, as well as on DB polarization. The study of DB at crystal surfaces is important because they can localize energy of order of 1 eV, which can reduce the potential barrier for local structure transformation or a chemical reaction. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract Microstructure and mechanical properties of the as-annealed Ti-stabilized Fe-17Cr ferritic stainless steel were investigated by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and tensile tests. Experimental results show that the size of the ferrite grain in the Fe-17Cr stainless steel is about 40 µm after rolling and annealing. Orientation distribution function (ODF) by EBSD indicates that nearly homogeneous {111} annealing texture is produced in the annealed sheets. Pole figures (PF) by EBSD show that Kurdjumov–Sachs orientation relationship between the TiN particles and ferrite grains is established in the as-annealed microstructure. Tensile tests demonstrate that the yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of the as-annealed Ti-stabilized Fe-17Cr ferritic stainless steel are 319 MPa, 626 MPa, and 36.5%, respectively. In the SEM micrograph of the fracture, deep dimples can be observed and TiN particles can be found in the core of the dimples, which indicates that the samples undergo large deformation before fracture. [ABSTRACT FROM AUTHOR]

Highlights • Atmospheric chloride deposition in field concrete at coastal region is studied. • Two-zone profile of chloride deposition content versus offshore distance is found. • Chloride deposition content increases and then fluctuates as altitude increases. • Building barrier and concrete surface orientation also affect chloride deposition. • Large temperature variation and rainfall facilitate the chloride deposition. Abstract A field research is carried out at atmospheric marine zones for evaluating the chloride deposition behavior of concrete structures under multiple geographic and environmental factors. Geographic factors of offshore distance, elevation, concrete surface orientation and building barrier, and environmental factors of temperature variation and rainfall on chloride deposition of concrete surface layer are evaluated. Our investigation demonstrates that chloride deposition content is significantly affected by offshore distance, elevation, and building barrier. Effect of concrete surface orientation on chloride deposition depends on the presence of building barrier. Besides, the large temperature variation and rainfall facilitate the chloride deposition. [ABSTRACT FROM AUTHOR]

Highlights • Epibenthic communities are similar at standing and reefed platforms at 30 m deep. • Epibenthic community structure differs between depths of 5 and 30 m. • Motile fauna densities are greater at 5 m than at 30 m. • Reefing does not affect the food web structure of epibenthic communities. • Reefed platforms serve a similar ecological function as standing platforms. Abstract Fossil fuel extraction in the Gulf of Mexico currently involves the use of approximately 2000 active oil and gas production platforms. These artificial structures provide a number of ecological functions including habitat provision for epibenthic invertebrates and production of food and refuge for a variety of fish species. To mitigate the loss of habitat when active platforms are decommissioned, Rigs-to-Reefs programs maintain existing communities by removing the upper 26 m of platform structure and converting upper and lower portions into artificial reefs. We examined the epibenthic communities of two standing platforms at 5 m and 30 m depths and three reefed platforms at 30 m depths. A combination of stable isotope and community analysis was used to assess the structure and food web functioning of epibenthic communities among these site-types. Reefed platforms (30 m) supported communities with similar food web structure as 5 m and 30 m standing platform communities. However, community composition in standing platform and reefed platform sites at 30 m differed from those of standing platform sites at 5 m depths. Results indicate that, although loss of shallow water habitat associated with platform reefing may diminish some aspects of biodiversity, reefed platforms support similar fundamental ecological functions as standing platforms in the Gulf of Mexico. Thus, the current reefing practice of removal of the upper 26 m of the structure does not substantially influence the functionality of these systems, and the retained structure maintains beneficial habitat for epibenthic communities. [ABSTRACT FROM AUTHOR]

Highlights • Single phase (10 1 ¯ 1), (10 1 ¯ 2) and (20 2 ¯ 3) GaN grown on 4°-miscut 3C-SiC/Si. • Different Al x Ga 1−x N interlayers used to control GaN surface orientations. • Substrate miscut caused twins in (10 1 ¯ 1) GaN. • (10 1 ¯ 2) and (20 2 ¯ 3) GaN only grown along the miscut direction. Abstract Heteroepitaxial growth of GaN buffer layers on 3C-SiC/(001) Si substrates (4°-miscut towards [110]) by metalorganic vapour phase epitaxy has been investigated. High-temperature grown Al x Ga 1 - x N/AlN interlayers were employed to control GaN surface orientations. Semipolar GaN layers with (10 1 ¯ 1), (20 2 ¯ 3) and (10 1 ¯ 2) surface orientations were achieved, as confirmed by X-ray diffraction. Due to the substrate miscut, the growth of (10 1 ¯ 1) layers was twinned along [ 1 1 ¯ 0 ] 3 C - SiC / Si and [ 1 ¯ 10 ] 3 C - SiC / Si while the growth of (20 2 ¯ 3) and (10 1 ¯ 2) layers was only along [ 110 ] 3 C - SiC / Si . The (10 1 ¯ 1) layers have rough surface morphology while the (20 2 ¯ 3) and (10 1 ¯ 2) layers have mirror-like smooth surface. For all samples with various surface orientations, different photoluminescence peak emission energies were observed at ∼ 3.45 eV, 3.78 eV and 3.27 eV at 10 K. These emissions are attributed to the near-band edge of hexagonal GaN, basal-plane stacking faults and partial dislocations, respectively. The dominant luminescence intensity of stacking faults indicates their high density in the GaN layers. [ABSTRACT FROM AUTHOR]

The current paper presents a combined ab initio and experimental study of H 2 adsorption on carbon. Adsorption energetics of a H 2 molecule on pristine graphene were obtained for various molecule orientations, showing that the perpendicular-to-surface orientation is energetically more preferable ( E ads  = −0.076eV/H 2 ) than the parallel orientations ( E ads ≈−0.071eV/H 2 ). Subsequently, B, Co, Ni, Pd, Pt and Ru substituents of a C atom in graphene were considered, leading to the conclusion that Pt and Ru promote the H 2 adsorption by ≈−0.012eV/H 2 . Pt promotes adsorption in all its neighbouring hexagons, while Ru impact is localised to the position directly above the dopant. Pure, Pt and Ru-doped ordered mesoporous carbon samples were evaluated experimentally for their H 2 adsorption performance under a low-pressure regime (up to 1 bar) at cryogenic and room temperatures ( i.e., 77 and 298 K, respectively). These experimental measurements indicated that, while the specific area of the metal-decorated carbons is lower than that of the pristine carbon material, the presence of Pt and Ru nanoparticles leads to a slight improvement of the H 2 uptake performance at room temperature. [ABSTRACT FROM AUTHOR]

Highlights • Surface orientation, roughness and chemical composition alter recruitment over time. • Orientation (light) an early primary driver of community structure. • Roughness mitigates effects of surface orientation over time. • Addition of chemical cues may faciliatate ‘selection’ of ecosystem engineers. • Surface modifications enhance biodiversity, habitat function and service provision. Abstract Worldwide, coastlines are becoming increasingly hardened by infrastructure in response to population growth, need for space, and coastal protection. Coastal and marine infrastructure (CMI) supports fewer species and lower abundance and diversity than analogous natural rocky habitats, which can alter community composition and ecosystem functioning. Efforts to develop ecological engineering solutions that offset these negative consequences on biodiversity while retaining engineering function abound, but to date few studies have investigated the role of multiple factors simultaneously driving patterns of biotic colonisation. Here, the role of surface heterogeneity, chemical composition and surface orientation was evaluated over a 6-month period. An increase in habitat heterogeneity, the replacement of shale for ground oyster shell (cue) and downward orientation was predicted to increase species richness, diversity and abundance. Orientation and heterogeneity greatly affected species richness, abundance, and community composition, and the inclusion of ground oyster shell (cue) increased bivalve recruitment but had only a marginal effect on community structure. Community formation was facilitated by low light but inhibited by sedimentation. On upward-facing surfaces, sediment accumulation on high complexity surfaces expanded niche heterogeneity, and supported communities comprised of burrowing polychaetes and predatory species. Surface orientation and heterogeneity are key factors influencing larval recruitment, and in supporting diverse benthic assemblages on artificial structures. These factors should be considered during the design phase of new engineering projects if the negative consequences of artificial structures are to be minimised while ensuring engineering function is maintained. [ABSTRACT FROM AUTHOR]

Highlights • Increasing surface orientation brought decreased boiling incipience superheat. • Boiling hysteresis was found to vary with surface orientation. • A temperature overshoot higher than that of onset of nucleate boiling was observed. • Thermal boundary layer and bubble stirring action mechanism were proposed. Abstract Herein, the effect of surface orientation on the onset of nucleate boiling from microporous coated surfaces was investigated experimentally. Based on different surface orientations—which varied from horizontal facing upwards to horizontal facing downwards—it is proven that the onset of nucleate boiling surface superheat decreased as the orientation angle increased for both microporous surface and plain surface. Additionally, during the incipience boiling period, a temperature overshoot was observed. This largest temperature overshoot was found decreased with increasing orientation angle. The thermal boundary layer and the stirring effect of bubble flow were attributed to these phenomena. It was also found that even at higher wall temperatures, the heat transfer coefficient at the largest temperature overshoot point was still higher than the onset of nucleate boiling point. Increasing orientation angles yielded higher heat transfer coefficients through increased thermal boundary layer temperature and promoted nucleate boiling. [ABSTRACT FROM AUTHOR]

Measurements have been made near normal incidence of the two-dimensional spatial coherence of the acoustic field scattered from the lakebed in Seneca Lake, New York. In the test region, the lakebed consists of a series of sediment layers created by a sequence of distinct depositional processes. The spatial coherence length of the scattered field is shown to be dependent on the structure of the underlying sediment sequences. Significant ping-to-ping variability in the spatial coherence surface was also observed for each sediment sequence. This variability is quantified by a two-dimensional spatial coherence metric that measures the coherence lengths and asymmetric coherence surface orientation. The ping-to-ping variation of the surface asymmetry appears to be linked to the spatial isotropy of the sediment scattering strength. The scattering strength of the deepest observed sequence in the sub-bottom is the most spatially isotropic and the ping-to-ping variability of the coherence lengths and surface orientations are random. The scattering strength of the shallower sequences is spatially anisotropic and the coherence lengths and surface orientations show intervals of non-random ping-to-ping behavior. [ABSTRACT FROM AUTHOR]

Charge carrier kinetics of hematite films prepared via atomic layer deposition and solution-derived methods were investigated using heterodyne transient grating technique in aqueous solution, depending on bias voltage, to reveal the effects of surface orientation differences on the charge carrier dynamics. We found that the electron/hole recombination in atomic layer deposited hematite was slower than that in solution-derived hematite, indicating the generated charge carriers in atomic layer deposited hematite can survive longer than that in solution-derived hematite, which is usually beneficial for water oxidation. On the other hand, the trapping dynamics of the long-lived holes to the surface state for water photo-oxidation in the solution-derived hematite was observed at faster time region than that in atomic layer deposited hematite, implying that the diffusion of the holes in atomic layer deposited hematite was slower than that in solution-derived hematite due to the different barrier height and width of the space charge layer which strongly depends on the surface orientations. It means that the low charge carrier mobility rather than the retardation of the charge recombination in the atomic layer deposited hematite is a dominant factor in its low photoelectrochemical performance. [ABSTRACT FROM AUTHOR]

In the scientific research, calculations of roughness parameters are carried out, with the aim of comparing measured values of roughness parameters with the calculated ones by normal random field equations. First of all, roughness measurement experiments for surfaces with irregular roughness are carried out to determine the roughness parameters and the ordinate distribution histograms using modern measuring equipment Taylor Hobson Talysurf Intra 50. Using the obtained experimental data, Pearson criterion calculations are made in order to check the compliance of surface ordinate distribution function to normal Gaussian distribution law. The obtained results showed that for all investigated samples the surface ordinate distribution function complies with normal Gaussian distribution law. The next step is the calculation of several 3D roughness parameters (from the standard ISO 25178-2). According to the obtained results it is concluded that the calculated values of surface roughness parameters Sa, Sp, Spc, Sdq, Sdr are quite close to the values obtained by measuring equipment Taylor Hobson. The acquired formulas may be applicable for determination of 3D roughness parameters. [ABSTRACT FROM AUTHOR]

It is demonstrated that the surface-relief orientation in the form of one-dimensional gratings with a period of 1.20 ± 0.02 μm formed under processing of hydrogenated-silicon films by femtosecond laser pulses (1.25 μm) with an energy density of 0.15 J/cm2 is determined by the direction of the polarization vector of the radiation and total laser exposure. Based on the results of the analysis of Raman spectra, the presence of a nanocrystalline phase of silicon with a volume fraction between 15 and 67% (depending on processing conditions) is detected. The observed processes of micro- and nanostructuring are caused by excitation of the surface plasmon-polaritons and nanocrystallization in the near-surface region in the field of high-power femtosecond laser pulses, respectively. In addition, formation of polymorph modifications of silicon Si-III and Si-XII under femtosecond laser processing with a number of pulses exceeding 500 is discovered. Anisotropy of the Raman signal for the above polymorph modifications is revealed. [ABSTRACT FROM AUTHOR]

We report results of a systematic study on the complex oscillatory current-driven dynamics of single-layer homoepitaxial islands on crystalline substrate surfaces and the dependence of this driven dynamical behavior on important physical parameters, including island size, substrate surface orientation, and direction of externally applied electric field. The analysis is based on a nonlinear model of driven island edge morphological evolution that accounts for curvature-driven edge diffusion, edge electromigration, and edge diffusional anisotropy. Using a linear theory of island edge morphological stability, we calculate a critical island size at which the island’s equilibrium edge shape becomes unstable, which sets a lower bound for the onset of time-periodic oscillatory dynamical response. Using direct dynamical simulations, we study the edge morphological dynamics of current-driven single-layer islands at larger-than-critical size, and determine the actual island size at which the migrating islands undergo a transition from steady to time-periodic asymptotic states through a subcritical Hopf bifurcation. At the highest symmetry of diffusional anisotropy examined, on {111} surfaces of face-centered cubic crystalline substrates, we find that more complex stable oscillatory states can be reached through period-doubling bifurcation at island sizes larger than those at the Hopf points. We characterize in detail the island morphology and dynamical response at the stable time-periodic asymptotic states, determine the range of stability of these oscillatory states terminated by island breakup, and explain the morphological features of the stable oscillating islands on the basis of linear stability theory. [ABSTRACT FROM AUTHOR]

Amethod to analyze the kinetics of the charge accumulation in the tunnel oxide by the nand flash memory program and erase (P/E) cycling is proposed. Both electron trapping and detrapping processes are required to be considered owing to the oxide high electric field during P/E cycles. Consequently, the electron trapping in the deep trap state is concluded, whose trap energy (Etrap) is more than 3.5 eV. Furthermore, the as-grown trap state density (Ne), the trapping capture cross section (σ ), and the number of trapped positive charges can also be extracted to explain the tunneling current modulation and the VT shift by oxide-trapped charges under the P/E stress. The trapped electronsaremainly distributedin the centerof tunneloxide, and the distributed area extends as the P/E bias increases. In addition, the dependence of oxidation process is also shown. Both thermal dry and plasma oxidation have almost thesame value of σ (~4x10-17 cm²).However,30% reduction of Ne is shown in plasma oxidation (~1.25x1019 cm-3) when compared with thermal dry oxidation (~1.88 x 1019 cm-3). [ABSTRACT FROM AUTHOR]

Most research efforts focus on synthesis of new biocides. This study shows that orientating biocidal groups on top surface with the help of a low-surface-tension constituent also imparts enhanced antibacterial ability. A CO2-philic biocidal silicone with pyridinium pendants was synthesized by hydrosilylation reaction of (45% methylhydrosiloxane)–dimethylsiloxane random copolymer (P(MHS–DMS)) and 4-vinylpyridine and subsequent quaternization of pyridine groups with 6-perfluorooctyl-1-bromohexane. The fluorinated pyridinium silicone was impregnated into cotton yarns in supercritical CO2 to form a 50 nm thickness biocidal layer at 24 MPa and 50 °C. Pyridinium groups preferentially segregated to the top surface with the aid of low-surface-tension perfluorooctyl segments and provided higher biocidal efficacy against Staphylococcus aureus and Escherichia coli compared to their counterparts that were quaternized with 1-bromohexane at similar total pyridinium content of about 4.65 × 1016/cm2. The synthesis and coating results were characterized by FTIR, SEM, and XPS. The stabilities of fluorinated pyridinium silicone layer toward washing cycles, UV irradiation, and storage were good. The presented strategy uses environmentally benign CO2 as solvent and affords a general method to functionalize polymers for improved biocidal capability due to the surface orientation of pyridinium groups. [ABSTRACT FROM AUTHOR]

A fundamental problem in extracting scene structure is distinguishing different physical sources of image structure. Light reflected by an opaque surface covaries with local surface orientation, whereas light transported through the body of a translucent material does not. This suggests the possibility that the visual system may use the covariation of local surface orientation and intensity as a cue to the opacity of surfaces. We tested this hypothesis by manipulating the contrast of luminance gradients and the surface geometries to which they belonged and assessed how these manipulations affected the perception of surface opacity/translucency. We show that (i) identical luminance gradients can appear either translucent or opaque depending on the relationship between luminance and perceived 3D surface orientation, (ii) illusory percepts of translucency can be induced by embedding opaque surfaces in diffuse light fields that eliminate the covariation between surface orientation and intensity, and (iii) illusory percepts of opacity can be generated when transparent materials are embedded in a light field that generates images where surface orientation and intensity covary. Our results provide insight into how the visual system distinguishes opaque surfaces and light-permeable materials and why discrepancies arise between the perception and physics of opacity and translucency. These results suggest that the most significant information used to compute the perceived opacity and translucency of surfaces arise at a level of representation where 3D shape is made explicit. [ABSTRACT FROM AUTHOR]

The iron content in Ni-Cr- x Fe ( x = 0–9 at.%) alloys strongly affected the properties of oxide films after 978 h of immersion in the simulated PWR primary water environment at 310 °C. Increasing the iron content in the alloys increased the amount of iron-bearing polyhedral spinel oxide particles in the outer oxide layer and increased the local oxidation penetrations into the alloy matrix from the chromium-rich inner oxide layer. The effects of iron content in the alloys on the oxide film properties after 500 h of immersion were less significant than those after 978 h. Iron content increased, and chromium content decreased, in the outer oxide layer with increasing iron content in the alloys. Increasing the immersion time facilitated the formation of the local oxidation penetrations along the matrix/film interface and the nickel-bearing spinel oxides in the outer oxide layer. [ABSTRACT FROM AUTHOR]

Device-quality crystallographically oriented epitaxial (100)Ge and (110)Ge were grown on GaAs substrates using a large bandgap AlAs buffer. Electrical characteristics of p-type metal-oxide-semiconductor (pMOS) capacitors, fabricated from the aforementioned material stacks, are presented for the first time. High-resolution cross-sectional transmission electron microscopy analysis demonstrated atomically abrupt heterointerfaces between Al2O3/Ge as well as Ge/AlAs for both (100) and (110) orientations. Various process conditions were implemented during MOS capacitor fabrication to study their impact on the Al2O3/Ge interface. The fabricated pMOS devices demonstrated excellent electrical characteristics with efficient modulation of the Fermi level from midgap to the conduction band edge, corresponding to a minimum Dit value of 1.2 × 1011 cm-2·ev-1 on (100)Ge, indicative of a high-quality oxide/Ge heterointerface, and an effective electrical passivation of the Ge surface. Postdeposition annealing under O2 was found to be less effective at reducing oxide trap density (NOT) as compared to forming gas or O2 postmetallization anneals (PMA), indicating that metal-induced bandgap states at the gate metal/dielectricinterface have a notable impact on Ge pMOS NOT. On the other hand, a tradeoff must be made between NOT and the equivalent oxide thickness when performing PMA under O2 or forming gas ambient. [ABSTRACT FROM PUBLISHER]

The oxygen reduction reaction (ORR) at iridium single crystalline electrodes, Ir(111) and Ir(332), in 0.1 M HClO 4 and 0.5 M H 2 SO 4 solution, was studied using cyclic voltammetry and potential step chronoamperometry under a hanging-meniscus rotating disk electrode configuration. The results are compared to the ORR behaviors observed on platinum single crystal electrodes with the same surface orientation. We found that i) The kinetics for ORR on Ir(111) are significantly slower than those on Pt(111), the onset potential and half-wave potential for ORR are ca. 100 mV and 370 mV more negative than those on Pt(111), respectively; ii) in 0.1 M HClO 4 only H 2 O 2 is formed on Ir(111) at E > 0.55 V, and when E < 0.4 V the major product is H 2 O, in 0.5 M H 2 SO 4 a significant amount of H 2 O 2 is produced even the potential is as low as 0.15 V; iii) Ir(332) exhibits lower ORR activity than Ir(111), with a half-wave potential that is ca. 30 mV more negative, and the diffusion-limited ORR current is not reached from 0.8 V down to 0.05 V, indicating that at Ir(332), incomplete reduction of O 2 to H 2 O 2 occurs in a wide potential region; iv) significant decay of ORR current with potential scan rate and reaction time in the current transient measurements are observed on both Ir(111) and Ir(332), similar to those observed on Pt(111) and Pt(332) electrodes. The structure-activity relationship of Ir(hkl) toward ORR is discussed. [ABSTRACT FROM AUTHOR]

This paper presents a detailed theoretical analysis of the implications of nanoscale device structures on the average hole ballistic velocity calculated from quantum-mechanical strain-dependent 6\times 6~\text k \cdot \text p band-structure simulations. The simulations show that the crystallographic orientation of the uniaxial strain, channel, and surface affect the average ballistic velocity by modifying the energy–momentum (E − k) dispersion of the subbands (from which the ballistic velocity is calculated). Conversely, the analysis shows that semiconductor-body thickness and gate architecture influence the ballistic velocity by modifying the quantum confinement in the structure, which ultimately affects the relative hole occupation of k -states across different subbands. Key results of the work show that a 5-nm-body thickness yields a 6%–12% increase in the ballistic velocity compared to a 10-nm body. Likewise, a single-gate architecture gives up to an 11% increase over a double gate, but the improvement is dependent on the crystallographic surface orientation. Strained Ge shows a significantly enhanced ballistic velocity relative to strained Si for both {100}- and {110}-surface orientations with a predicted hole ballistic velocity exceeding 2 \times 10^7 cm/s at \textn_\texts^\textv+ = 5 \times 10^12 #/cm2. [ABSTRACT FROM PUBLISHER]

Electromagnetic emission (EME) generated by fracture of carbon fibre reinforced polymers (CFRP) is studied. The fracture is induced to cross-ply CFRP by mechanical loading in a three-point bending configuration. An EME acquisition set-up operating on the principle of capacitive coupling is used to measure the low frequency (kHz-MHz range) electric field whose generation is attributed to the charge redistribution accompanying the fracture processes. Multiple, differently oriented EME sensors, for the simultaneous EME measurement with different source-sensor orientations, were applied to account for the directionality of the EME sources and their generated electric fields. A method to deduce the crack orientation based on the emitted EME field's directionality is proposed. A comparison between the angles of the EME sources obtained by this method and the actual crack surface orientations as determined by computed tomography is made. [ABSTRACT FROM AUTHOR]

Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is applied to study orientation structures of polydimethylsilane (PDMS) films deposited on heteroatom-doped graphite substrates prepared by ion beam doping. The Si K -edge NEXAFS spectra of PDMS show opposite trends of polarization dependence for non irradiated and N 2 + -irradiated substrates, and show no polarization dependence for an Ar + -irradiated substrate. Based on a theoretical interpretation of the NEXAFS spectra via first-principles calculations, we clarify that PDMS films have lying, standing, and random orientations on the non irradiated, N 2 + -irradiated, and Ar + -irradiated substrates, respectively. Furthermore, photoemission electron microscopy indicates that the orientation of a PDMS film can be controlled with microstructures on the order of μm by separating irradiated and non irradiated areas on the graphite surface. These results suggest that surface modification of graphite using ion beam doping is useful for micro-orientation control of organic thin films. [ABSTRACT FROM AUTHOR]

In multiscale modeling of the morphological evolution of plasma facing materials in nuclear fusion reactors, the knowledge of the timescales of the involved physical processes is important. In the present study, a new method based on molecular dynamics simulations was developed to extract the lifetime of helium bubbles near tungsten surfaces. It was found that the lifetime of a helium bubble can be described by the Arrhenius equation. However, the lifetime of a helium bubble depends on the thickness of tungsten film above the helium bubble in the substrate and the bubble size. The influence of surface orientations on the lifetime of helium bubbles was also observed, and the performance of helium bubbles on the (1 1 1) surface is very different from on the (0 0 1) and (0 1 1) surfaces. The role of the helium bubble lifetime in other simulation techniques, such as in kinetic Monte Carlo methods and rate theory, is discussed. [ABSTRACT FROM AUTHOR]

A reorientation of cholesteric liquid crystal with a large helix pitch induced by the electrically controlled ionic modification of the surface anchoring has been studied. In initial state, the cholesteric helix is untwisted completely owing to the normal surface anchoring specified by the cations adsorbed at the substrates. As a result, the homeotropic director configuration is observed within the cell. Under the action of DC electric field, one of the substrates becomes free from the layer of surface active cations, therefore, setting the planar surface anchoring. The latter, in turn, leads to the formation of the hybrid chiral structure. The threshold value and dynamic parameters have been estimated for this process as well as the range of control voltages, which do not allow the electrohydrodynamic instabilities. The twisted hybrid director configuration observed in the experiment has been analysed by means of the simulation of polarisation change of light propagating through the cholesteric layer with asymmetric (planar and homeotropic) surface anchoring on the cell substrates. [ABSTRACT FROM AUTHOR]

Homoepitaxial growth film for (001), (110) and (111) Ni substrates is investigated by means of molecular dynamics (MD) simulation. Embedded atom method (EAM) is considered to represent the interaction potential between nickel atoms. The simulation is performed at 300K using an incident energy of 0.06eV. In this study, the deposition process is performed periodically and the period, , is relative to a perfect layer filling. The coverage rate of the actual expected level, , can be considered a determinant for thin-film growth of nickel. The level is the most filled level during the deposition on (001) substrate, while it is the less filled one in the case of (111) substrate. Moreover, the upper level is the one which is responsible for the surface roughness and the appearance time of an upper layer may also be a factor influencing the surface roughness. The deposition on (111) substrate induces the most rigorous surface with a rapid appearance time of the upper layers. The layers are almost completely filled for all substrates. The and lower layers are completely filled for (001) and (110) substrates while for (111) substrate the completely filled layers are and lower ones. [ABSTRACT FROM AUTHOR]

We report the formation and evolution mechanisms of HSFLs (high-spatial-frequency laser-induced periodic surface structures) on the commercial pure titanium under 10-ps 532-nm-wavelength laser irradiation. At a lower peak laser fluence, HSFLs in the rough zone are first formed along the surface texture. Subsequently, HSFLs in the flat zone are formed with an orientation parallel to the laser polarization direction. The formation of HSFLs can be attributed to the parallel orientation of the initial periodic modulation of the electron plasma concentration to the laser polarization direction. In particular, the formation of HSFLs along the surface texture occurs because the absorbed laser energy density is along the surface texture. At a higher peak laser fluence, two types of HSFLs appear together with LSFLs. The first type involves HSFLs that initially cover the concave part of the LSFL (low-spatial-frequency laser-induced periodic surface structures) and penetrate inward as the number of spot overlaps increases. This formation mechanism can be attributed to cavitation instability. The second type involves HSFLs that are initially in the convex part of the LSFL, and they are transformed into oxidized nanodots as the number of spot overlaps increases. The oxidized nanodots increase the absorption of laser energy in titanium, which leads to the ablation and removal of the oxidized material. Therefore, the surface of the LSFL becomes smooth. [ABSTRACT FROM AUTHOR]

The present study aims to investigate the effect of the exposure angle (0°, 30°, 45°, 60° and near 90°) and the number of exposed faces (skyward and downward surfaces) on the immersion corrosion behavior of a dual phase and a mild steel in freely aerated stagnant 3.5% NaCl solution for a period of 10 days. In one case, two surfaces are exposed simultaneously, whereas in other case, one of the surfaces is exposed, while other is lacquered. Analysis shows that the corrosion rate of the skyward surface is considerably high when both the surfaces are exposed. The corrosion rate of the downward surface is higher than that of the skyward sample, when one of the surfaces is exposed. Moreover, the corrosion rate gradually decreases from zero to near-90° orientation for all the cases. Though the effect of tilt angle and exposed face does not depend on steel varieties, the dual-phase steel has higher corrosion resistance than the mild steel. Relative oxygen content, microcell formation, gravity effect and reaction nature with depth are the plausible reasons for the observed variation of corrosion behavior. [ABSTRACT FROM AUTHOR]

Single crystalline and textured In 2 O 3 thin films with (1 1 1) surface orientation, grown by plasma-assisted molecular beam epitaxy, were used as a model system to study the role of bulk and surface electron accumulation layer conductance for ozone sensing. Both conductance contributions, which add to the total film conductance, were systematically varied. The resulting ozone sensitivity was determined by total conductance measurements in synthetic air with defined ozone concentration using UV irradiation instead of heating to regenerate the In 2 O 3 surface. Depletion of the surface electron accumulation by an oxygen plasma treatment, confirmed by X-ray photoelectron spectroscopy, rendered the films ozone insensitive. The ozone response of films with an accumulation layer was increased by thickness reduction or by designing the bulk of the film semi-insulating using deep acceptor doping by Mg. Our results of using electron accumulation layers for gas sensing and bulk doping by deep acceptors to increase sensitivity can be generalized to other gas sensing materials. The use of single crystalline films allows selecting the most sensitive crystallographic surface orientation and may have further advantages over polycrystalline films, such as increased stability and sensing speed. [ABSTRACT FROM AUTHOR]

The low-index surfaces of TiC are studied using the first-principles method based on density functional theory. The surface energy of TiC is calculated with consideration of the surface orientation, termination and carbon chemical potential, as well as the influence of surface vacancy defects of various concentrations. It is found that the surface relaxation results in rumpling of the (001) and (110) surfaces and the contraction of the (111) surfaces. The relative stability of the low-index surfaces of TiC varies with the carbon chemical potential, surface defects and vacancy concentrations, which will have an effect on the nanoparticles morphology and catalytic performance in practical applications. The results will serve as a guidance for understanding and designing novel TiC nanocatalysts with special morphology. [ABSTRACT FROM AUTHOR]

The thermally activated escape of Eshelby dislocations in face-centered-crystal (FCC) nanowires of finite length with surface steps at the ends is investigated by combining atomistic and continuum models. The energy barriers for the dislocation escape from face-centered-cubic 〈110〉 nanowires are predicted from atomistic models as a function of nanowire radius, escape location, and surface step orientation. The dissociation of a dislocation into partials has a significant effect on the energy barrier. The dislocation prefers to escape from the end of nanowire with an extended node, where the dissociation width is greater than the equilibrium width in the bulk. The energy barrier is further lowered if the surface step aligns with the dislocation's slip plane. A continuum line tension model that accounts for partial dislocations is constructed and benchmarked against atomistic predictions for FCC nanowires. The continuum model is then used to make predictions on the stability of Eshelby dislocations over a wide range of nanowire radii. [ABSTRACT FROM AUTHOR]

The process of dissociation of a fluorine molecule on the (001) surface of germanium has been analyzed using density functional theory. Initial orientations of the F 2 molecule with respect to the substrate leading to its dissociative adsorption have been identified. Reaction paths at p(1 × 2) and c(2 × 4) reconstructed Ge(001) surfaces are different, but final configurations of the adsorbate/substrate system are found qualitatively the same. Adsorption energy of around 5 eV per molecule depends on the final arrangement of adatoms, being always higher for the p(1 × 2) substrate reconstruction. The energy barrier for dissociative adsorption of F 2 on Ge(001) is always less than 0.2 eV. The structural and electronic properties of distinct final adsorbate configurations have been examined, indicating that the surface density of states is metallic at Ge dimers with one adsorbed F atom and non-metallic at Ge dimers with two F adatoms. [ABSTRACT FROM AUTHOR]

Artificial reefs provide shelter and can be an important source of food for fish depending on the epibenthic community on the structure. The growth and diversity of this community is influenced by the substratum material and the surface orientation of the reef. Settlement plates of four materials (Perspex, sandstone, wood and steel) were deployed in three orientations (upwards, downwards and vertical) at a depth of 33 m on a designed artificial reef (DAR) off the coast of Sydney, Australia. After three months, the steel surfaces had lower invertebrate species richness, total abundance and diversity compared to other surfaces. Steel was not an ideal material for the initial recruitment and growth of epibenthic invertebrates. A longer duration would be required to develop a mature epibenthic community. Surface orientation had species-specific impacts. Surface material and orientation are important factors for developing epibenthic assemblages, and are thus likely to affect the broader artificial reef assemblage, including fish. [ABSTRACT FROM PUBLISHER]

By the local electroreflectance method the topographic analysis of Ge1-x Six monocrystal surface was performed. The influence of the surface orientation on defects density distribution was found. Topographic maps of the defectiveness distribution on the crystal surfaces with (111) and (110) orientations were constructed and visualized. [ABSTRACT FROM AUTHOR]

The selective epitaxial growth of Si1-xGex and the related strain properties were studied. Epitaxial Si1-xGex films were deposited on (100) and (110) orientation wafers and on patterned Si wafers with recessed source and drain structures via ultrahigh vacuum chemical vapor deposition using different growing steps and Ge concentrations. The stepwise process was split into more than 6 growing steps that ranged in thicknesses from a few to 120 nm in order to cover the wide stages of epitaxial growth. The growth rates of SiGe on the plane and patterned wafers were examined and a dependence on the surface orientation was identified. As the germanium concentration increased, defects were generated with thinner Si1-xGex growth. The defect generation was the result of the strain evolution which was examined for channel regions with a Si1-xGex source/drain (S/D) structure. [ABSTRACT FROM AUTHOR]

The basic wall boiling model widely used in computation fluid dynamics codes gives no regard to influences of surface orientation upon boiling mechanism. This study aims at examining the effects of surface orientation on wall heat flux and bubble parameters in pool nucleate boiling and incorporating those into the wall boiling model. Boiling experiments on a flat plate heater submerged in a pool of saturated water were conducted under atmospheric pressure. Relevant bubble parameters as well as boiling heat transfer characteristics were simultaneously measured using a unique optical setup integrating shadowgraph, total reflection and infrared thermometry techniques. It was observed that as an upward-facing heater surface with a constant wall superheat of 7.5 °C inclines from horizontal towards vertical, the heat flux significantly increased; nucleation site density increased intensively at the upper part of the heater surface where thermal boundary layer might become thickened; isolated boiling bubbles tend to slide up due to buoyancy and coalesce with each other, thus forming one single large bubble. Such observations on the wall heat flux and bubble parameters according to surface orientation could not be predicted by the present basic wall boiling model only centered with isolated bubbles. A modified wall boiling model incorporating the effects of merging of isolated bubbles on an inclined surface was proposed. The model reasonably predicted the experimental data on various orientation angles. [ABSTRACT FROM AUTHOR]

The orientation dependence of the visible-light stimulated photochemical reduction of aqueous Ag+ on polycrystalline hematite Fe2O3 was determined by observing the relative amount of reduced Ag0 on crystals of known surface orientation over all possible orientations. The results show that surfaces oriented within 20° of the (1102) plane are the most active and surfaces close to the (0001) plane are the least active. A strong correlation is observed between the orientation-dependent activity and the orientation-dependent surface potential measured by scanning Kelvin probe force microscopy. Surfaces near the most active (1102) plane and the least active (0001) plane are, respectively, at the most positive and the least positive ends of the potential range among all grains. The trends in activity are concluded to arise from a combination of internal fields associated with surface charges and bulk transport effects. [ABSTRACT FROM AUTHOR]

The orientation dependence of the visible-light stimulated photochemical reduction of aqueous Ag+ on polycrystalline hematite Fe2O3 was determined by observing the relative amount of reduced Ag0 on crystals of known surface orientation over all possible orientations. The results show that surfaces oriented within 20° of the (1102) plane are the most active and surfaces close to the (0001) plane are the least active. A strong correlation is observed between the orientation-dependent activity and the orientation-dependent surface potential measured by scanning Kelvin probe force microscopy. Surfaces near the most active (1102) plane and the least active (0001) plane are, respectively, at the most positive and the least positive ends of the potential range among all grains. The trends in activity are concluded to arise from a combination of internal fields associated with surface charges and bulk transport effects. [ABSTRACT FROM AUTHOR]

Current plasmonic metasurfaces of nanocubes are limited to planar configurations, restricting the ability to create tailored local electromagnetic fields. Here, we report a new chemical strategy to achieve tunable metasurfaces with nonplanar nanocube orientations, creating novel lattice-dependent field localization patterns. We manipulate the interfacial behaviors of Ag nanocubes by controlling the ratio of hydrophilic/hydrophobic molecules added in a binary thiol mixture during the surface functionalization step. The nanocube orientation at an oil/water interface can consequently be continuously tuned from planar to tilted and standing configurations, leading to the organization of Ag nanocubes into three unique large-area metacrystals, including square close-packed, linear, and hexagonal lattices. In particular, the linear and hexagonal metacrystals are unusual open lattices comprising nonplanar nanocubes, creating unique local electromagnetic field distribution patterns. Large-area "hot hexagons" with significant delocalization of hot spots form in the hexagonal metacrystal. With a lowest packing density of 24%, the hexagonal metacrystal generates nearly 350-fold stronger surface-enhanced Raman scattering as compared to the other denser-packing metacrystals, demonstrating the importance of achieving control over the geometrical and spatial orientation of the nanocubes in the metacrystals. [ABSTRACT FROM AUTHOR]

Using molecular-dynamics simulation, we study the scratching of Ti and Mg crystals by a hard tip. Both the basal and a prismatic surface orientations are considered. We focus on the characterization of defects and plasticity in the crystal. Among the various types of dislocations generated the partials b = 1 3 〈 1 ¯ 1 0 0 〉 are most prominent. During scratch dislocation reactions constantly reorganize the dislocation network adherent to the scratch groove. Plastic activity is more pronounced for the prismatic surface, where dislocation loops – mainly consisting of b = 1 3 〈 2 ¯ 1 1 0 〉 and 1 3 〈 1 ¯ 1 0 0 〉 dislocations – are emitted into the substrate. Under the basal surface I 2 intrinsic stacking faults, corresponding to b = 1 3 〈 1 ¯ 1 0 0 〉 partials are formed parallel to the scratch groove bottom, while they are oriented perpendicular to the surface under the prismatic surface. We find that mainly the { 0 1 1 ¯ 0 } 〈 2 ¯ 1 1 0 〉 slip system is activated, and relate the form of the pile-up generated to this slip. The tangential hardness is systematically smaller than the normal hardness under scratching. The basal surface has smaller hardness than the prismatic surface. [ABSTRACT FROM AUTHOR]

We investigated the influence of the surface orientation of La0.8Sr0.2CoO3 (LSCO) on the catalytic activities for oxygen evolution and reduction reactions in alkaline solutions when using single crystals of LSCO. When LSCO single-crystal rods are sliced along the (001), (110), and (111) planes of a high-temperature cubic structure, we obtain crystal electrodes that can be denoted (001)C, (110)C, and (111)C, respectively. The catalytic activities for oxygen evolution occur in the order (110)C> (001)C≈(111)C. Although the currents for oxygen reduction on LSCO single crystals are hardly observed, their activities are enhanced when carbon is placed on the crystal surfaces. These results clearly show that the oxygen evolution activities of LSCO electrodes are dependent on their crystal planes, whereas their oxygen reduction activities rely on the interplay between carbon and LSCO. These findings may contribute toward the development of an effective electrocatalyst for rechargeable air electrodes. [ABSTRACT FROM AUTHOR]