Substrate Inclination Research Articles

Spatial segregation of two common Gobius species (Teleostei: Gobiidae) in the northern Adriatic Sea

AbstractThe habitat characteristics and spatial segregation of the two common gobies Gobius fallax Sarato, 1889 and Gobius auratus Risso, 1810 were investigated by fish frequency and abundance estimates through visual counts in the northern Adriatic Sea. The latter species is represented by a recently described, unusual colour morph in the northern Adriatic Sea. Gobius fallax was observed at five of the nine locations examined and its abundance did not differ between two of three transect locations at Piran (Slovenia) and at the western coast of Cres (Kvarner region, Croatia). Gobius auratus was not found in the Gulf of Trieste but was present at several Kvarner locations, and co‐occurred with G. fallax at one location at Cres. Both inhabit rocky substrates but they show different preferences for substrate inclinations and bathymetric segregation. Gobius fallax was most frequent between 2 and 8 m depth and was most abundant on substrate inclining less than 30°. Its highest abundance over entire transects was 0.3 indiv.·m−2 but within certain transect sections this increased to 1.25 indiv.·m−2. Gobius auratus attained its highest abundance in depths below 8 m and at substrate inclinations between 30 and 90°. This species attained its highest values at the western coast of Cres, where it reached a maximum of 1.5 indiv.·m−2 over entire transects but even up to 3.0 indiv.·m−2 in certain transect sections. At Krk, the maximum abundance over entire transects was only 0.3 indiv.·m−2.

Effect of substrate inclination on the magnetic anisotropy of ultrathin Fe films grown on Al2O3(0001)

We have investigated the effect of substrate inclination on the in-plane magnetic anisotropy of ultrathin Fe films grown on Al2O3(0001). For Fe films grown on flat Al2O3 substrates, no preferred direction of magnetization exists in the film plane due to the three equivalent epitaxial orientations of Fe(110) that form. However, for Fe grown on an inclined Al2O3 substrate, a uniaxial anisotropy appears that is parallel to the step edges. The anisotropy increases in magnitude with decreasing Fe thickness and growth temperature, and as the surface morphology changes from being rough to being smooth. We attribute the uniaxial anisotropy to the effective demagnetization field caused by the surface corrugation.

Growth and properties of YBCO-coated conductors on biaxially textured MgO filmsprepared by inclined substrate deposition

YBa2Cu3O7−δ (YBCO) filmswere fabricated on SrRuO3 (SRO)-buffered MgO templates grown on Hastelloy C276 metallic substrates, on which theMgO layers had been deposited by inclined substrate deposition (ISD) using electron beamevaporation. YBCO and SRO films were deposited by pulsed laser deposition (PLD).ISD-MgO substrates fabricated with two different substrate inclination angles(α = 35° and 55°) were used to grow YBCO films. High transport critical current density,Jc = 1.4 × 106 A cm−2, has been measured at 77 K in self-field for YBCO film grown on ISD-MgO withα = 35°, whereas YBCO film grown on ISD-MgO withα = 55° had alower Jc = 0.5 × 106 A cm−2. X-ray pole figure patterns revealed a cube-on-cube orientationrelationship among YBCO, SRO, and ISD-MgO films, with thec-axis of the YBCO filmbeing tilted. X-ray ω and ϕ-scans revealed good in-plane and out-of-plane textures of YBCO film grown on ISD-MgOsubstrate. The YBCO film grown on ISD-MgO with substrate inclination angleα = 35° had a YBCO(005)ϕ-scan full widthat half maximum (FWHM) = 5.8° and a YBCO(007) ω-scan FWHM = 2.8°, whileYBCO film with α = 55° had YBCO(005) ϕ-scan FWHM = 5.4° andYBCO(007) ω-scan FWHM = 2.6°.

Delayed onset of return flow by substrate inclination in model horizontal longitudinal MOCVD processes

In this study an experimental flow visualization is carried out to investigate how the substrate inclination affects the buoyancy-induced return flow structure in mixed convection of gas in a horizontal rectangular duct. The return flow is driven by a heated circular disk embedded in the bottom plate of the duct, simulating that in a horizontal longitudinal MOCVD reactor. Specifically, the bottom plate of the duct is inclined so that the gas flow in the duct is accelerated, causing the buoyancy-to-inertia ratio to decrease in the main flow direction. In the experiment, the Reynolds and Rayleigh numbers of the flow at the duct inlet are respectively varied from 3.7 to 79.7 and from 9040 to 24,000 for the inclined angle of the bottom plate fixed at 0°, 0.34° and 0.97°. Particular attention is paid to delineating the spatial changes of the return flow structure with the plate inclination angle and to how the bottom plate tilting possibly suppresses and stabilizes the flow. The results show a substantial delay in the onset of the return flow and the effective suppression of the buoyancy-driven unstable vortex flow by the bottom plate inclination. Besides, the bottom plate inclination can effectively weaken the return flow at slightly higher Reynolds numbers. An empirical equation is provided to correlate the present data for the onset of the return flow in the duct with its bottom inclined at 0° and 0.97°.

Biodiversity of zoobenthic hard-substrate sublittoral communities in the Eastern Mediterranean (North Aegean Sea)

The spatial dispersion of zoobenthos from sublittoral hard substrate communities in the northern part of the Aegean Sea has been studied during summer 1997 and 1998. Material was collected by SCUBA diving, by totally scraping off five replicate quadrates (400 cm 2 each) at three depth levels (15, 30, 40 m) from six sites located in Chalkidiki peninsula, plus one in Kavala Gulf. The examination of the 19,343 living specimens collected revealed the presence of 314 species. Though the multivariate analyses showed high similarity between stations, the structure of this sciaphilic algal community seems to have an increased spatial heterogeneity. Four distinct facies were recorded in accordance with the occurrence of different algal forms, the degree of hard substrate inclination and the water clarity. A short review on the biodiversity of sublittoral communities in the Mediterranean revealed the affinity between the western and the eastern basin and also among the photophilic and the sciaphilic algal communities.

Patterns of sponge distribution in Cagarras Archipelago, Rio de Janeiro, Brazil

The structure and distribution of the sponge community in five sites and four habitats in Cagarras Archipelago, Rio de Janeiro, Brazil, are described. The archipelago has three major islands (Cagarra, Palmas, and Comprida), and four islets. Qualitative samples were taken by SCUBA diving in the three islands and in two islets, and quantitative samples were taken in Palmas Island only. Cluster analysis using Jaccard's coefficient on qualitative data grouped the two islets (Cagarra Bank and Cagarra Islet), which are more exposed to wave action, and the three islands formed a group of relatively sheltered sites. Cluster analysis using Bray–Curtis coefficient on quantitative data from different habitats in Palmas Island allowed distinction of three groups of samples: overhangs, shallow horizontal surfaces (6 m depth), and vertical walls plus deeper horizontal surfaces (17 m depth). Sponge abundance was greater in overhangs (61·2 ind m−2), which were dominated by Protosuberites sp. and Clathrina conifera. Abundance was reduced in vertical walls (31·1 ind m−2) and deep horizontal surfaces (16·8 ind m−2). Pachychalina sp. dominated the deep horizontal surfaces and Clathrina conifera was dominant in overhangs. Values of Shannon's diversity in overhangs, vertical walls (both with H′=2·1 bits ind−1) and deep horizontal surfaces (H′=1·7 bits ind−1) were moderate and similar, whereas in shallow horizontal surfaces the sponges were both less diverse (H′=0·37) and less abundant (8·5 ind m−2). Shallow horizontal surfaces were dominated by Hymeniacidon heliophila. The reduced species richness of the sponge community in Cagarras Archipelago when compared with other sites in Brazil and elsewhere is probably due in part to the pollution from the city of Rio de Janeiro. Wave action appears to reduce the number of sponge species at a local scale, whereas substrate inclination affects more strongly the species composition and abundance than the diversity of sponges.

Transition from superparamagnetic to ferromagnetic state of ultrathin Fe films grown on inclined Al 2O 3(0001) substrates

The magnetic states of 10 ML Fe films grown on inclined Al 2O 3(0001) substrates were investigated in the transition region of superparamagnetic to ferromagnetic states. The ratio of the superparamagnetic and ferromagnetic components is dependent on both the growth temperature and the inclination of the substrate. The maximum ratio of the ferromagnetic to superparamagnetic was observed in ultrathin Fe films grown on flat substrates at a growth temperature of 473 K. The difference in crystallinity of Fe at each temperature explains the observed behavior. On the other hand, the ratio of ferromagnetic to superparamagnetic components for Fe films grown on inclined substrates behaves in a complex manner with the growth temperature and is also influenced by the uniaxial magnetic anisotropy, which is induced by the inclination of substrate.

Thickness dependence of magnetic state of Fe thin films grown on Al2O3(0001) substrates with an inclined angle

We have investigated the magnetic state of Fe thin films grown on Al2O3(0001) inclined substrates at the Fe thickness range of 5–25 ML (monolayer) (1.0–5.0 nm). For 5 ML Fe films, the magnetic state is superparamagnetic state and the effect of inclination of substrate is negligible. The magnetic state of 10 ML Fe films is in the coexistence of superparamagnetic state and ferromagnetic state, and the effect of inclination of substrate appears but is still a little. In the ferromagnetic region, above Fe thickness of 15 ML, the magnetic easy axis is influenced by the inclination of substrate. Fe thin films grown on the flat substrate have no preferred direction of magnetization in the film plane because of the three equivalent variants of the epitaxial Fe(110) on Al2O3(0001). On the other hand, Fe thin films grown on the inclined substrate have a uniaxial magnetic anisotropy, in which the magnetic easy axis is parallel to the step edge. The strength of uniaxial magnetic anisotropy decreases with increasing Fe thickness. This uniaxial magnetic anisotropy might be derived from the effective demagnetization field due to the magnetic charge distribution at the corrugated surface caused by the steps.

INCLINED SUBSTRATE DEPOSITED CeO2 FILMS BY ELECTRON BEAM EVAPORATION ON RANDOMLY ORIENTED METALLIC SUBSTRATE

A study on CeO 2 film growth on randomly oriented metallic substrate using lnclined Substrate Deposition (ISD) technique was performed in order to develop a biaxially aligned buffer layer for YBa 2 Cu 3 O 7-δ (YBCO) coated conductors. The influence of deposition parameters, as the substrate inclination angle α with respect to the CeO 2 vapor direction, deposition temperature and film thickness, on structural and morphological properties of the film was investigated. At substrate temperature between 200°C and 700°C a biaxial texture was observed for α ranging from 15° to 75°. The minimum value of the ϕ-scan full width at half maximum (FWHM) on (002) poles of about 13.5° was obtained for film 2 μm thick deposited at 200°C and α=55°. Morphological analyses on cross-sectioned samples revealed a columnar structure, typical for this deposition technique, with spaced grains and a tile like surface.

Characterization of nitride thin films by electron backscatter diffraction.

Thin films incorporating GaN, InGaN and AlGaN are presently arousing considerable excitement because of their suitability for UV and visible light-emitting diodes and laser diodes. However, because of the lattice mismatch between presently used substrates and epitaxial nitride thin films, the films are of variable quality In this paper we describe our preliminary studies of nitride thin films using electron backscattered diffraction (EBSD). We show that the EBSD technique may be used to reveal the relative orientation of an epitaxial thin film with respect to its substrate (a 90 degrees rotation between a GaN epitaxial thin film and its sapphire substrate is observed) and to determine its tilt (a GaN thin film was found to be tiltedby 13 +/- 1 degrees towards [1010]GaN), where the tilt is due to the inclination of the sapphire substrate (cut off-axis by 10 degrees from (0001)sapphire towards (1010)sapphire). We compare EBSD patterns obtained from As-doped GaN films grown by plasma-assisted molecular beam epitaxy (PA-MBE) with low and high As4 flux, respectively. Higher As4 flux results in sharper, better defined patterns, this observation is consistent with the improved surface morphology observed in AFM studies. Finally, we show that more detail can be discerned in EBSD patterns from GaN thin films when samples are cooled.

Stick Insects Walking Along Inclined Surfaces

In the experiments stick insects walk on an inclined substrate such that the legs of one side of the body point uphill and the legs of the other side point downhill. In this situation the vertical axis of the body is rotated against the inclination of the substrate as if to compensate for the effect of substrate inclination. A very small effect has been found when the experiment was performed with animals standing on a tilted platform which shows that the effect depends on the behavioral context. When, however, animals first walked along the inclined surface and then, before measurement, stopped walking spontaneously, a rotation of the body has been observed similar to that in walking animals. In a second experiment it was tested whether the observed body rotation is caused by the change of direction of gravity vector or by the fact that on an inclined surface gravity necessarily has a component pulling the body sideways. Experiments with animals standing on horizontal ground and additional weights applied pulling the body to the side showed similar body rotations supporting the latter idea. In a simulation study it could be shown that the combined activity of proportional feedback controllers in the leg joints is sufficient to explain the observed behavior. This is however only possible if the gain factors of coxa-trochanter joint controller and of femur-tibia joint controller show a ratio in the order of 1 : 0.05 to 1 : 1.8. In order to describe the behavior of animals standing on a tilted platform, a ratio of 1 : 1.7 is necessary. In walking animals, this body rotation requires to change the trajectories of stance and swing movements. The latter have been studied in more detail. During swing, the femur-tibia joint is more extended in the uphill legs. Conversely, the coxa-trochanter joint appears to be more elevated in the downhill legs which compensates the smaller lift in the femur-tibia joint. The results are discussed in the context of different hypotheses.

Seasonal Dynamics of a Subtidal North-Western Mediterranean Macroalgal Community in Relation to Depth and Substrate Inclination

In the present study we describe, throughout a single year, subtidal macroalgal assemblages present on a shallow platform and on a deep cliff, using species and functional groups as descriptors. The study site is located south of Leghorn in the north-western Mediterranean Sea. Univariate and multivariate analyses were performed to detect spatial and temporal variations. A total of 101 macroalgal species were found: 17 Chlorophyta, 13 Phaeophyta and 71 Rhodophyta. The shallow platform assemblage was more structured than that on the cliff, in fact the number of species was higher and a well developed stratified structure, consisting of turf, encrusting and erect vegetation layers was present. On the platform, functional groups showed qualitative and quantitative seasonal variations, while the cliff assemblage exhibited a dominance of crustose species throughout the year. The species richness found in the present study is lower than that observed in other Mediterranean macroalgal assemblages. This condition may be linked both to the spread of Womersleyella setacea turf, that may exclude other macroalgae by overgrow and pre-emption, and to the stress caused by sediment deposition and burial, that may damage macroalgal growth and recruitment. The multidimensional scaling analysis, performed both on the samples-species matrix and on the samples-functional groups matrix, showed a similar pattern, even if the use of species-level approach permitted a more accurate description of the assemblages.

Deep level study in epitaxial 4H-SiC grown on substrates inclined toward <1 100>

AbstractEpitaxial layers of 4H-SiC are grown on (0001) substrates inclined toward <1120> and <1100> directions. Defects in these films are characterized by deep level transient spectroscopy (DLTS) in order to clarify the dependence of concentrations and activation energies on substrate inclination. DLTS results show no such dependence on substrate inclination but show thickness dependence of the concentration.

Syntaxonomy and environmental gradients of the grasslands of the Stormberg / Drakensberg mountain region of the Eastern Cape, South Africa

A phytosociological classification of the grassland communities of the Stormberg / Drakensberg mountain chain and surrounding lowlands in the Eastern Cape is presented. The study area was firstly stratified on the basis of Acocks's (1988) Veld Types and then within Veld Types on local topography. An initial classification was derived by using two-way indicator species analysis (TWINSPAN) followed by table refinement according to the methods and techniques of the Braun-Blanquet school of phytosociology. Seven grassland associations and eleven sub-associations are formally described. Syntaxa are described using diagnostic floristic elements and characterised using habitat criteria. Annual rainfall and elevation related strongly to floristic gradients, and substrate and slope inclination accounted for local vegetation floristic and structural differences. Species richness was found to be highest in associations with high structural diversity and species turnover was strongest where environmental heterogeneity was high.

Transmission electron microscopy investigation of texture development in magnesium oxide buffer layers

Biaxially textured magnesium oxide (MgO) buffer layers were grown by inclined substrate deposition and examined before YBa/sub 2/Cu/sub 3/O/sub 7-x/ deposition to optimize their texture. Transmission electron microscopy of buffer layers in both cross-sectional and plan view was used to investigate film microstructure and texture development as a function of deposition thickness (0.05-3 /spl mu/m) and substrate inclination angle (0-55/spl deg/ from the substrate normal). It was determined that the combined effects of preferential growth of the {200} equilibrium crystal habit of MgO and shadowing by columnar grains led to the development of off-axis [200]-textured films.

Preventing snow accumulating upon inclined substrates using falling water film

This paper has concerned preventing snow accumulating upon inclined substrates using falling water film. A cluster of physical models for a gas–water–snow system was developed and solved with a control-volume finite-difference procedure. The effects of various parameters on heat transfer and water film temperature decrease were investigated. The results revealed that it is feasible to use falling water film to prevent snow accumulation upon inclined substrates as long as the suitable initial film flow rate and temperature are adopted. It was clarified that among the influential factors of water film temperature decrease, the snowfall intensity, initial water film thickness and the substrate inclination play an important role. The intensity of the film temperature decrease mainly depends on the snowfall intensity and the initial heat capacity of the water film flow, which is a function of temperature and mass flow rate. An intensive heat transfer occurs in a very thin layer near the free surface of the water film. The numerical results were correlated in terms of effective Nusselt number, and Reynolds, Prandtl and Gukhman numbers. The maximum deviation of the numerical data from the correlation is approximately 15.6%, which only causes an uncertainty less than 3% in the simple prediction.

The microstructure of YBa/sub 2/Cu/sub 3/O/sub 7-δ/ films and yttria stabilised zirconia buffer layers deposited on inclined Hastelloy substrates

YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films have been grown on polycrystalline metallic substrates using intermediate yttria stabilised zirconia (YSZ) buffer layers. The buffer layers were grown by pulsed laser deposition using the inclined substrate deposition technique, whereby the substrate is tilted so that the ablated species arrive under an oblique incidence angle. One of the consequences of the inclined geometry is the alignment of the buffer layer crystal grains within the plane of the film which enables the subsequent deposition of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films With J/sub c/s of up to 10/sup 5/ A/cm/sup 2/. We present results showing that the optimum substrate inclination angle for the YSZ buffer layer deposition is around 55/spl deg/, and that the in-plane alignment improves linearly with film thickness. We also show transmission electron micrographs which demonstrate that grain sizes get larger and appear to be better aligned towards the buffer layer surface. We use these results to propose a mechanism by which texture occurs during inclined substrate deposition. The mechanism is based on three requirements inferred from our microstructural data: columnar growth, tilting of grains towards the incoming ablated species, and a preferred growth orientation normal to the substrate surface.

Bimonthly Characterization And Behavior Of The Sessile Community Associated With The Rocky Littoral Of Bocachica, Tierra Bomba Island, Colombian Caribbean

A total of ten fixed transects were sampled at two-month intervals during one year at the rocky littoral of Bocachica, Tierra Bomba Island, Colombian Caribbean. The census technique used was the transect-chain method. The zonation pattern observed was similar to that of other Caribbean locations. The characteristic species of the mesolittoral were the vermetid Dendropoma corrodens and the sponge Tedania ignis. The characteristic species of the infralittoral were the corallinacea alga Peyssonnelia sp.and one undetermined species (morphotype 1). The other 54 species were less abundant and occasional. A disturbance factor was found consistent with the advance and withdrawal of the sand plane on thesublittoral, which clearly affected the width of the littoral zones. This perturbation had no correlation with rain or the current regime, but it had a weak one with substrate inclination. The relative fluctuation in the width of the zones was highest in the supralittoral and lowest in the mesolittoral. The spatial classification and ordination analyses of the transects showed a spatial pattern dependent on the differential grade of exposure to the wind and waves. This was particularly notorious in one of the steepest and most exposed transects. The temporal classification and ordination of the transects showed an ordered pattern of change clearly correlated with the sampling month. The monthly samplings corresponding to the rainy season (May to November) and the monthly samplings corresponding to the dry season (January to May) revealed two distinct groups. The last sampling month (May) was placed apart from the initial sampling month (May of the previous year), which suggests a cycle longer than one year.

Inclined Substrate Deposition by Evaporation of Magnesium Oxide for Coated Conductors

AbstractBiaxially textured MgO buffer layers were deposited on metal substrates using “inclined substrate deposition” (ISD). The influence of the substrate inclination angle, deposition rate, and film thickness on the texture is shown. Scanning electron microscopy reveals columnar growth. We developed a growth model to explain the texturing. To test this model we have carried out 3D Monte-Carlo simulations. We find that the preferred orientation arises from mutual shadowing of the columns and directional surface diffusion due to their initial momentum.YBa2Cu3O7 (YBCO) films deposited on the ISD buffer layers are highly textured. The ab-planes of the YBCO are tilted with respect to the surface by typically 25° towards the direction of MgO vapor incidence. Therefore, the critical current density jc is anisotropic with up to 8 × 105MA/cm2 in one direction and 4 × 105MA/cm2 in the other. For tape coating the MgO deposition direction can be chosen so that the high jc is along the tape.

Inclined Substrate Deposition by Evaporation of Magnesium Oxide for Coated Conductors

AbstractBiaxially textured MgO buffer layers were deposited on metal substrates using “inclined substrate deposition” (ISD). The influence of the substrate inclination angle, deposition rate, and film thickness on the texture is shown. Scanning electron microscopy reveals columnar growth. We developed a growth model to explain the texturing. To test this model we have carried out 3D Monte-Carlo simulations. We find that the preferred orientation arises from mutual shadowing of the columns and directional surface diffusion due to their initial momentum.YBa2Cu3O7 (YBCO) films deposited on the ISD buffer layers are highly textured. The ab-planes of the YBCO are tilted with respect to the surface by typically 25° towards the direction of MgO vapor incidence. Therefore, the critical current density jc is anisotropic with up to 8 × 105 MA/cm2 in one direction and 4 × 105 MA/cm2 in the other. For tape coating the MgO deposition direction can be chosen so that the high jc is along the tape.