Effect Of Substrate Type Research Articles

The Effect of Substrate Type on SiC Nanowire Orientation

beta-SiC nanowires were synthesized on different monocrystalline substrates: Si (001), Si (111), 3C-SiC (001), 4H-SiC (0001), 6H-SiC (0001). The SiC nanowire growth was carried out using a Chemical Vapor Deposition method, with silane and propane diluted in hydrogen (3%) as precursors. The deposition was performed at atmospheric pressure and at 1100 degrees C, after dewetting of the Ni catalyst, which had been previously evaporated onto the substrate, to induce 1D growth according to a VLS process. The crystal structure of the nanowires, as determined by X-ray diffraction and High Resolution Transmission Electron Microscopy, corresponds to 3C-SiC polytype growing along a (111) direction, irrespective of the substrate. The occurrence of (111) stacking faults was observed, partly reduced for samples grown on 3C-SiC substrate. The growth on (111) substrate allowed to achieve a good vertical alignment of the nanowires, as investigated by Scanning Electron Microscopy. High Angle Annular Dark Field imaging and Energy Dispersive X-Ray spectroscopy were performed to study the catalyst particle on top of the wires and showed the formation of a nickel-silicon alloy.

The Effects of Substrate Type on Diatom-Based Multivariate Water Quality Assessment in a Tropical River (Monjolinho), São Carlos, SP, Brazil

Diatoms are good indicators of water quality in lotic systems. Unlike in the temperate region, the effect of substrate on diatom-based water quality assessment in tropical streams is not fully understood. The purpose of this study was to assess the effect of substrate on diatom-based multivariate water quality assessment. Epilithic, epiphytic, epipsammic and epipelic diatom community and water quality sampling was done four times at 10 sites during the dry season (2008 and 2009). Artificial substrates (brick and glasses) were also placed at the sampling sites during this period and sampled after 1 month. Cluster analysis was performed to show the main differences and similarities in community composition amongst substrates sampled and amongst sampling sites. The IndVal method was used to identify indicator species characterising different substrates. Canonical correspondence analyses (CCAs) were performed to relate the structure of diatom communities from different substrates to predictor variables. A gradient of increasing metal and organic pollution, eutrophication and ionic strength was observed from the agricultural/forested area to the urban area. Diatom community structure closely reflected this gradient, with communities from polluted sites (8, 9 and 10) being different from other communities. Polluted sites were associated with such species as Nitzschia palea, Plantago lanceolata, Achnanthes exigua, Caloneis hyaline, Cyclotella meneghiniana, Gomphonema parvulum, Fallacia monoculata, Luticola goeppertiana, Pinnularia microstauron, Pinnularia subcapitata and Sellaphora pupula. Indicator species analysis showed that common diatom species were not restricted to a single substrate, though preference was generally high for natural (especially macrophytes) compared to artificial substrates. Six CCAs corresponding to six substrates performed to relate diatom community structure to simultaneous effects of predictor variables explained ∼50% of the diatom species variance in all cases and roughly separated highly polluted sites from the rest of the sites. This indicates that the results of diatom-based multivariate water quality assessment based on different substrates may be interchangeable. Only one substrate has to be collected at each site for water quality assessment surveys, thus avoiding unnecessary expensive and time-consuming oversampling. Given the limitations of artificial substrates, sampling of natural substrates is highly recommended.

Effect of Substrate Type on the Electrical and Optical Properties of Cold-sputtered Indium Tin Oxide Films as a function of Post-deposition Heat Treatment

AbstractIndium Tin Oxide (ITO) films were deposited by RF sputtering onto glass and quartz substrates with no external heating. An ITO target containing 10 wt% SnO2 was used for the deposition in a Kurt Lesker PVD75 system, in an atmosphere of 50% O2 + 50% Ar. Post-deposition heat treatments were done on these coatings at 150°C, 300°C and 450°C in an atmosphere of commercial air or argon. The effects of these heat treatments on the microstructure and the properties of the films were evaluated using atomic force microscopy, resistivity measurements, and UV-visible absorption spectroscopy. The heat treatments were observed to significantly affect the properties such as transmittance in the visible region, optical band gap and the electrical resistivity of the films. The main differences are caused by the differences in thermal expansion coefficient of the substrates as compared to the sputtered ITO films.

Reactive DC Magnetron Sputtering of Vanadium Oxide Thin Films

Vanadium oxides are a class of materials with outstanding physical and chemical properties. They find a wide field of technological applications such as optical and electrical switching devices, light detectors, temperature sensors, micro batteries, etc. There are several studies regarding the production of vanadium oxide films by radio-frequency (RF) magnetron sputtering, and with increasing interest on the thermochromic VO2 phase. However, literature with focus on vanadium oxide films deposited by direct current (DC) magnetron sputtering is very limited. In this work, we have successfully deposited vanadium oxide thin films by reactive DC magnetron sputtering under several processing conditions. The effect of substrate type, temperature, and O2/Ar flow ratio on phase formation has been studied. Structural analysis and phase determination have been carried out by X-ray diffractometry (XRD). Some single phase samples were also analysed with respect to surface morphology by means of scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thermochromic behaviour of single phase VO2(M) films has been evaluated by optical spectrophotometry.

EFFECT OF VARIABLES ON PERFORMANCE OF SURFACE WASHING AGENTS UNDER A NEWLY DEVELOPED TESTING PROTOCOL

ABSTRACT Surface washing agents (SWAs) can be used following an oil spill event to enhance the removal of stranded oil from shorelines and other surfaces. The U.S. Environmental Protection Agency (EPA) has developed a testing protocol to evaluate the effectiveness of SWAs in the laboratory. Using this protocol, the effects of substrate type, substrate hydration, and SWA-to-oil ratio (SOR) on the ability of SWAs to remove crude oil were evaluated. Experiments were conducted using Prudhoe Bay Crude (PBC) oil applied to three substrates under wet and dry conditions. Oil recovery efficiencies were similar for substrates made up of sand and the smaller of two gravels, while a decrease in efficiency was observed for the larger, more heterogeneous gravel. For the controls without SWA, after we compared dry and wet substrates, we decided dry substrates would be preferable for purposes of the protocol because variability was much lower and differences between treated and control samples were greater. To determine the effect of SOR, four SWAs were evaluated at three SORs and two dilutions for their efficiency in removing PBC from dry sand. Oil recovery efficiency as a function of SOR was lower at the low SOR ratios (1:1 <2:1 <10:1). Application of equivalent volumes of 50% and 100% SWA solutions to PBC revealed that efficiency increased with applied mass of SWA. However, when equal masses of SWA were applied at 10:1 SOR, similar efficiencies were achieved regardless of dilution. This suggests that, except at the highest application rate, total applied mass is a more critical variable than dilution for these SWAs. IFO180 Fuel Oil was also evaluated under these conditions. Preliminary data suggest lower SWA efficiencies were observed with this heavier weight oil.

Electrical and optical study of ITO films on glass and polymer substrates prepared by DC magnetron sputtering type negative metal ion beam deposition

Transparent, conducting indium tin oxide (ITO) films were deposited without intentional substrate heating on glass and polyethersulfone (PES) substrates by a magnetron sputter type negative metal ion source (MSNIS). The effect of substrate type on optical transmittance, electrical resistivity, surface morphology and roughness of the ITO film was analyzed. ITO/glass substrates show a higher optical transmittance (89%) and lower resistivity (4 × 10 −4 Ω cm) than ITO/PES (78%, 6 × 10 −4 Ω cm). X-ray diffraction (XRD) spectra indicate polycrystalline ITO films deposited on glass and amorphous ITO films on PES. Atomic force microscopy (AFM) images also indicate that ITO/glass has a lower surface roughness than ITO/PES. The values of figure of merit ( T 10/ R sh) for ITO/glass ( ϕ TC = 7.7 × 10 −3 Ω −1) are higher than ITO/PES ( ϕ TC = 1.3 × 10 −3 Ω −1), indicating that ITO/glass achieved the best performance in this study.

Experimental analysis of recruitment patterns of coral reef fishes in seagrass beds: Effects of substrate type, shape, and rigidity

Habitat choice of reef fish larvae at settlement is one of the mechanisms proposed to explain spatial patterns in the distribution of fishes and the corresponding spatial structure of communities. Field experiments using Pomacentridae were conducted at Iriomote Island, southern Japan, in order to determine if rare recruitment of coral reef fishes in seagrass beds is due to larval settlement preference. When three types of natural patch treatments (branching coral patch, seagrass patch, and control without patches) were established in cleared seagrass squares in the center of a seagrass bed, four pomacentrid species, Amblyglyphidodon curacao, Dischistodus prosopotaenia, Cheiloprion labiatus, and Dascyllus aruanus, recruited exclusively onto the coral patches, indicating that larvae distributed in the seagrass bed may have preferred a coral rather than seagrass substrate as a settlement habitat. The effects of differences in physical shape (grid structure for branching coral vs. vertical structure for seagrass leaves) and rigidity (rigid substrate for coral vs. flexible substrate for seagrass) between coral and seagrass substrates on such recruitment patterns were investigated using artificial coral and seagrass units. When artificial habitat units with predator exclusion cages were established in the cleared seagrass squares as above, high densities of A. curacao and D. prosopotaenia recruits were observed on the rigid rather than flexible habitat units (both unit types having similar shape), whereas differences in recruit numbers of the two species were unclear in differently shaped units. These results demonstrated that even though pomacentrid larvae are distributed in the seagrass bed, they do not settle on the seagrass substrate owing to their habitat choice being partially based on a preference for substrate rigidity. Moreover, non-recruitment of C. labiatus and D. aruanus on artificial habitat units suggested that the presence of living coral substrates rather than physical shape/rigidity of substrates are an important cue for habitat choice of these fishes.

Rock crab predation of juvenile sea scallops: the functional response and its implications for bottom culture

The functional response describes how consumption rate of individual predators changes as prey density changes, and can have important implications for the bottom culture of scallops. We examined (i) the functional response of rock crabs (Cancer irroratus) preying on juvenile sea scallops (Placopecten magellanicus); (ii) the effect of substrate type and scallop size on the functional response; and (iii) the underlying behavioural mechanisms of observed functional responses. Specifically, we quantified predation rate and behaviours, such as the proportion of time spent searching for prey, encounter rate between predators and prey and the outcomes of encounters, when individual rock crabs were offered a range of scallop density (2–50 or 11–111 scallops m−2) and two size classes of scallops (∼ ∼25 and ∼ ∼35 mm shell height) on two different substrate types (“glass-bottom” and “granule”). We found that crab predation rate on small juvenile scallops increased at a decelerating rate with prey density to a plateau at high prey density on both substrates, indicating a hyperbolic (type II) functional response. Crab predation rate on large juvenile scallops was independent of prey density (i.e., no functional response evident), suggesting that crabs were at their satiation level. Prey density did not influence any behaviour except encounter rate on small juvenile scallops, which increased as prey density increased. Substrate type influenced crab predation: maximum predation rate of crabs on small juvenile scallops and encounter rate with either size of juvenile scallops was lower on granule than on glass-bottom. Our results in the laboratory suggest that crabs could potentially be swamped if scallops are seeded at a high density in the field. However, many factors in the field may influence the functional response. For example, the presence of multiple prey types may lead to sigmoid functional responses, while the presence of many crab individuals may lead to aggregation of crabs in areas of high prey density.

Effects of Substrate Type on Plant Growth and Nitrate Leaching in Cut Flower Production of Oriental Lily

Four types of media [coir, 1 coir: 1 peat (by volume), peat, and sandy loam soil] were evaluated for their effects on plant growth and nitrate (NO –3) leaching in the production of oriental lilies (Lilium L.) `Starfighter' and `Casa Blanca'. Twenty-five bulbs were planted in perforated plastic crates and placed on the ground in temperature-controlled greenhouses. The potential for NO –3 leaching was determined by placing an ion-exchange resin (IER) bag under each crate at the beginning of the study. After plant harvest (14 to 16 weeks), resin bags were collected and analyzed for NO –3 content. Plant tissues were dried, ground, and analyzed for N content. Results indicated that the use of coir and peat did not significantly influence plant growth (shoot dry weight) relative to the use of sandy loam soil; however, substrate type influenced the amount of NO –3 leached through the media and N accumulation in the shoots for `Starfighter', but not `Casa Blanca'.

Effect of oxygen concentration in the sputtering gas and effect of substrate type on the electrical resistance of Bi:2201 nanoscale thin films

Bi:2201 nanoscale thin films were deposited onto SiTiO 3 and MgO substrates by using DC magnetron sputtering. The structural characterization was carried by X-ray diffraction. The film deposited onto SiTiO 3 substrate has better crystal quality than onto MgO substrate. The effect of different oxygen pressure ( f O 2 ) in the sputtering gas and the nature of the substrate on the electrical resistivity of thin films is presented. The electrical resistivity increases when the f O 2 content in the sputtering gas decreases. For the same value of f O 2 , the electrical resistivity is higher for films on MgO substrate than for films on SiTiO 3 substrate. For both substrates, in the lower temperature range, the underdoped films show a ln (1/ T) behavior of ρ( T).

Effect of substrate type on nanostructured titania sol–gel coatings for sensors applications

Titania coatings were obtained by the sol–gel method, starting from stable and transparent titania sol. Thin titania coatings were deposited onto different substrates: quartz glass, single crystal quartz (1 0 1), single crystal Si(1 0 0) and alumina. Effect of substrate type and heat treatment conditions on important characteristics determining the sensing properties were studied. Nanostructured titania coatings with grain size up to 50 nm and thickness less than 1 μm were obtained on all substrates, but their phase composition depends on substrate type. The slightly orientation of titania coatings as well as the interactions between titania coating and alumina and silicon single crystal were observed.

Effects of substrate type on growth and mortality of blue mussels ( Mytilus edulis ) exposed to the predator Carcinus maenas

Structure and complexity of the substrate are important habitat characteristics for benthic epifauna. The specific growth and mortality rates and inducible defence characters on medium-sized blue mussels (Mytilusedulis L.) exposed to shore crabs (Carcinusmaenas L.) were examined on three different substrate types in combined field and laboratory experiments. The experiments showed that complexity of the substrate increased blue mussel survival significantly, through a decrease in predation pressure. However, increased intraspecific competition for food on the complex substrate resulted in significantly lower growth rates of the mussels. Inducible defence characters were also influenced by substrate type. Blue mussels were more affected by predators on the structurally simple substrate, where they developed thicker shells and a larger posterior adductor muscle.

Random Copolymer Adsorption at the Polymer Melt/Substrate Interface: Effect of Substrate Type

Using low-energy forward recoil spectrometry (LE-FRES) and dynamic secondary ion mass spectrometry (DSIMS), we measure the interfacial excess, z*, and the volume fraction profiles of a bromine functionalized polymer chains at the polymer/inorganic substrate interface. Specifically, we investigate a blend of polystyrene (PS) homopolymer and a deuterium-labeled poly-d-(styrene-ran-4-bromostyrene) (dPBrxS) random copolymer, where the mole fraction of 4-bromostyrene units in the chain is x = 0.06. Our aim is to measure the strength of interaction of bromine functionalized segments of dPBr0.06S with silicon oxide, SiOx, and hydrogen-terminated silicon, SiH, surfaces. The results from both LE-FRES and DSIMS show that dPBr0.06S segregates at both polymer/SiOx and polymer/SiH interfaces, demonstrating that that the bromine groups do interact favorably with both surface types. We also use the self-consistent mean-field model (SCMF) to calculate the dPBr0.06S concentration profile and z* at the polymer/substrate interface and to determine the value of the interaction energy between 4-bromostyrene segments and the substrate. The comparison of experimental and SCMF results provides the interaction energy between the brominated polystyrene repeat unit and both substrate types, namely = −0.18kT and = −0.22kT. These results show that the interaction of the brominated segment with SiH surface is ca. 20% stronger than that with the SiOx surface.

Transparent semiconducting ZnO:Al thin films prepared by spray pyrolysis

Aluminum doped zinc oxide (ZnO:Al) films which can be used as transparent electrodes or heating layers have been deposited by the low cost spray pyrolysis technique. Undoped and Al-doped ZnO films deposited using various preparation conditions and on different substrates (soda lime glass, quartz glass and crystalline quartz, respectively) have been studied. The effect of substrate type, temperature, deposition time and doping concentration on ZnO:Al thin layers have been investigated by analysing the optical and structural properties of the films. A substrate temperature of 770 K allows the preparation of nanosized ZnO:Al crystals with preferred [002] orientation. Films with optical transmission T>85% and a adjustable resistivity ρ between 2 and 100 Ω cm have been obtained. The resistivity value of the films can be adjusted by tuning suitable processing parameters. The feasibility of the spray pyrolysis technique for the preparation of thin semiconducting ZnO:Al films on conventional soda lime glass substrates is demonstrated.

Surface Morphology and Wetting Behavior of Poly(α-methylstyrene) Thin Films Prepared by Vacuum Deposition

Poly(α-methylstyrene) of various molecular weights was vacuum-deposited on different substrates including glass, gold, and silicon. The effects of substrate type, as well as the molecular weight of the polymer, on the morphology and wettability of the deposited films were investigated. The advancing and receding contact angles of water on the surfaces were measured by the method of Wilhelmy plate. Besides, the film surfaces were characterized with scanning electron microscopy and electron spectroscopy for chemical analysis.. The results show that the growth of the polymer on gold tends to be of the Stranski−Krastanov mode, in which the growth leads to a smoother geometry. On the other hand, the growth on glass and silicon shows the island mode and results in a rougher surface. The differences in diffusion coefficients and viscosities of the polymers of various molecular weights cause distinct island population and surface structure. The contact angles of water on heterogeneous films were examined, and the influence of fractional coverage was interpreted using a theoretical model.

Effects of substrate type on the characteristics of GaN epitaxial films grown by molecular beam epitaxy

Films of GaN have been grown simultaneously on three different substrates, sapphire, silicon carbide and GaN, by molecular beam epitaxy. The structural and optical properties of the films have been studied using x-ray diffraction techniques and low-temperature photoluminescence spectroscopy respectively. There is a clear correlation between the structural and optical properties of the film and the nature of substrate. The lattice parameter of the film is shown to depend on the type of substrate. The incorporation of shallow donors is also strongly influenced. The effect of lattice parameter, mismatch and differential thermal expansion on film properties is discussed.

Biodesulfurization of Turkish lignites: 2. Microbial desulfurization of Mengen lignite by the mesophilic microorganism Rhodococcus rhodochrous

The effects of substrate type in the growth medium, mixing time of lignite into the growth medium and the biodesulfurization time on sulfur removal were studied. Biodesulfurization experiments were carried out with Mengen lignite under optimum growth conditions of Rhodococcus rhodochrous. The highest reduction of organic sulfur forms was 27.1% when sodium acetate was the substrate. Sulfate sulfur could be totally reduced when lignite was added to the culture medium 24 h after incubation. Compared with sodium acetate, glycerol yielded higher sulfate sulfur reduction rates when lignite was added at the time of incubation. The highest organic sulfur removal rates were found when sodium acetate was the substrate.

The Effect of Substrate Type and 2,2′-Bipyridine on the Sorption of Copper(II) on Silica and Alumina

AbstractWe have studied the co-adsorption of Cu(II) and an organic ligand, 2,2′-bipyridine (bipy), on amorphous silica (am-SiO2) and γ-Al2O3 (γ-alumina). This study focuses on two fundamental questions: (1) how bipy affects the macroscopic uptake behavior and molecular-scale characteristics of Cu(II) sorption complexes formed on each oxide; and (2) how and why the uptake behavior and the characteristics of Cu(II) sorption complexes differ for the two oxides. Solution uptake experiments and X-ray Absorption Fine Structure (XAFS) spectroscopy were used to answer these questions.In the absence of bipy and at a surface loading of approximately 0.05 μM/m2, Cu(II) adsorbs predominantly as a dimeric complex on am-SiO2 surfaces but as a monomeric complex on γ-Al2O3. At low Cu(II) to solid ratio, bipy shifts the pH of Cu(II) sorption on am-SiO2 to lower values, but it shifts the pH of Cu(II) sorption on γ-Al2O3 to higher values. Uptake experiments and XAFS measurements on the wet sorption samples indicate that sorption of aqueous Cu(bipy)2 on γ-Al2O3 displaces one bipy from the aqueous Cu(bipy)2 complex, while sorption on am-SiO2 does not disrupt the complex. More detailed XAFS analysis suggests an innersphere Cu(bipy)1 complex on γ-Al2O3 and a stronger Cu-surface oxygen interaction when Cu(bipy)2 adsorbs on γ-Al2O3 than am-SiO2.

The Effects of Substrate Type, Surface Water Depth, and Flow Rate on Manganese Retention in Mesocosm Wetlands

AbstractA wetland mesocosm experiment was conducted to determine the effects on Mn retention of substrate type, surface water depth, and flow rate. The main objective of this experiment was to determine if sustained Mn retention could be accomplished under the specific experimental treatments, to recommend design parameters for the construction of field wetland systems for Mn treatment. Crushed limestone was clearly superior to spent mushroom substrate (SMS) with respect to Mn retention. The presence of a layer of free surface water detracted from Mn treatment, while lower flow rates enhanced Mn treatment. Sustained Mn retention was achieved using crushed limestone as the substrate coupled with an absence of surface free water, when inlet water had a pH of 7.0 and no appreciable Fe. Substrate metal extractions indicated that most of the Mn was retained as oxide‐bound Mn (72%), with most (88%) of the Mn retained at the surface of the wetland. Limestone “wetlands” are therefore recommended in the treatment of Mn in neutral‐pH mine water containing no Fe.

Hole trap level generation in silicon during rapid thermal annealing: Influence of substrate type and process conditions

Hole trap level generation in boron-doped silicon by rapid thermal annealing between 900 and 1100 °C has been studied using deep level transient spectroscopy, with emphasis on the effects of substrate type and process parameters. A dominant hole trap level at Ev+0.30 eV and two accompanying hole trap levels at Ev+0.22 eV and Ev+0.40 eV in lower concentrations have been systematically detected in Czochralski, float zone, and epitaxial substrates, in a less than 5-μm-thick surface layer. The defect state concentrations were observed to increase monotonically with both the annealing temperature and the cooling rate. Higher concentrations of hole trap levels were measured in the Czochralski and epitaxial substrates than in the float zone substrate. Finally, both a silicidation and an oxidation reaction during the high-temperature plateau totally inhibited the formation of defect states. We suggest that the defect centers responsible for the observed hole trap levels could be formed during the high-temperature plateau with the participation of dissolved as-grown impurities and metal contaminants diffused from the wafer surface.