Effect Of Substrate Morphology Research Articles

Effect of substrate morphology on characteristics of layer-by-layer self-assembly nanofiltration membrane for micropollutants removal

Layer-by-layer (LBL) hollow fiber nanofiltration (NF) membranes have emerged as a promising technology for the removal of micropollutants (MPs). Previous research has been largely focused on polyelectrolyte pairs and coating parameters. This paper studied the substrate morphology, a critical factor often being overlooked. Poly (allylamine hydrochloride) /poly (styrene sulfonic acid) sodium salt (PAH/PSS) coating was utilized to evaluate the impact of the substrate morphology. Two polyethersulfone substrates were selected: Substrate 1# with dense skins at both lumen/shell and Substrate 2# with skin at the lumen and an open shell surface. All LBL NF membranes showed molecular weight cut-off ranging from 180 to 223 Da and MgCl2 rejection around 94 %. For LBL membrane 1#, with coatings on both shell/lumen sides, the outer coating was defective due to scratches. For LBL membrane 2# with a coating at the lumen, significant PAH overcompensation was observed, because of the open inner and outer surfaces comparing to LBL membrane 1#. Higher rejection to positively charged MPs was resulted from Donnan effect, outperforming steric exclusion. The backwash stability of both membranes was excellent and independent of the substrate structure. This work provides a basis for substrate selection for fabricating LBL NF membranes.

Zinc Nanoparticles Electrodeposited on TiO2Nanotube Arrays Using Deep Eutectic Solvents for Implantable Electrochemical Sensors

This work reports on the electrodeposition of zinc on nanoporous metal oxide titania nanotube arrays (TiO2 NTAs) using a zinc-containing deep eutectic solvent (Zn2+–DES). The effects of substrate morphology and crystallinity, deposition temperature, zinc concentration, and deposition time on the morphology and electrochemical properties of the Zn/TiO2 NTAs were investigated. Two-dimensional zinc nanohexagons (NHexs) with a mean diameter of ∼300 nm and a thickness of 10–20 nm were decorated onto the TiO2 NTAs (with a pore diameter of ∼80 nm and a tube length of ∼5 μm) via electrodeposition at −1.6 V using Zn2+–DES. Cyclic voltammetry tests on the Zn2+–DES electrolyte revealed an electrochemical window of ∼3.5 V, and the diffusion coefficient of Zn2+ was found to be 4.29 × 10–10 cm2 s–1 at room temperature and 7.10 × 10–10 cm2 s–1 at 40 °C. Zinc nucleation on TiO2 NTA substrates followed an instantaneous model. Using a higher electrodeposition temperature increased the nucleation and growth rate of zinc NHexs, while annealing TiO2 NTAs was found to improve their uniformity and morphology. During the initial stage of deposition, hexagonal close-packed zinc NHexs were found to preferentially grow on tetragonal anatase TiO2 NTAs. The electrodeposition of zinc resulted in lowering the impedance and improving the overall electrochemical properties of TiO2 NTAs. The Zn/TiO2 NTAs developed in this study offer a promising electrocatalyst material system for implantable electrochemical sensors.

Effects of substrate morphology on permeability spectra of Ni80Fe20 films deposited on periodically rippled sapphire substrates

Effects of substrate morphology on permeability spectra of Ni80Fe20 films deposited on periodically rippled sapphire substrates

Effect of substrate morphology on stress-tested GaN-on-GaN vertical p-n diodes

Effect of substrate morphology on stress-tested GaN-on-GaN vertical p-n diodes

Effect of substrate morphology on the deposition behavior of α-Al2O3 films by room temperature granule spray in vacuum process

In this study, we investigated the influence of surface morphology of a hard substrate on the deposition behavior of α-Al2O3 films coated by a granule spray in vacuum (GSV) process at room temperature. Three types of α-Al2O3 films were prepared by chemical vapor deposition (CVD) on a WC-Co base material: (006) textured film with a uniform and small mold-type morphology, (110) and (012) textured films with large grains and a relatively flat morphology, and flat (006) textured film after polishing. These CVD α-Al2O3 films were further coated with nano-grained α-Al2O3 films by the GSV process. The deposition behavior, adhesion strength, and residual surface stress were found to be strongly influenced by the surface morphology of the hard substrate. For the (006) textured CVD α-Al2O3 film with steep crests and troughs on the surface, the GSV α-Al2O3 film was deposited uniformly, possibly because the powder can be directly anchored by the molding effect and subsequent hammering effect. Such different deposition characteristics also led to a variation in the surface residual stress.

The influence of substrate morphology on the thermal radiation properties of SiC coating

SiC coating was prepared on the graphite substrate and the effects of substrate morphology on the thermal radiation properties of SiC coating were investigated. As the surface roughness of the graphite substrate decreasing from 2.95 to 0.68 μm, the total emissivity of SiC coating increased 28.33% at 1000 °C and 36.21% at 1600 °C, respectively. At the same time, the spectral emissivity of SiC coating on the graphite substrate all presented the obvious characteristic thermal radiation of SiC. Those results meant that the thermal radiation properties of the coating were both dominated by the substrate and coating. A simple coating model had been established to explain the effect of the substrate morphology on the heat flow between the substrate and coating. The rough substrate morphology enhanced the energy dissipation at interface and weakened the thermal radiation properties of coating finally.

Molecular dynamics research on geometric effect of nanostructured diamond-like carbon substrates on potassium stearate adsorption

Molecular dynamics (MD) simulations were performed to investigate the geometric effect of nanostructured substrates on adsorptive behavior of potassium stearate monolayers. A typical protective coating, diamond-like carbon (DLC), was employed as adsorptive substrates. For the substrates with square grooves, complete penetration of molecules can only occur under large width and small depth. The occurrence of partial penetration would make monolayer atoms away from substrate surfaces and therefore induce weak substrate-molecules interactions. Compared with the square groove bottoms, monolayers are much more strongly adsorbed to the groove concave corners. For substrates with triangle and semi-circle grooves, complete penetrations are achieved in both cases and thus monolayer atoms can interact with the whole groove surface. The effect of substrate morphology on monolayer adsorption would be sufficiently weakened by the decrease of geometric size, and the surface adsorptivity of semi-circle grooves with large radius is similar to that of the smooth surface. The results indicate that the substrates with triangle grooves have better adsorptivity than other morphologies.

Understanding the Integrity of Coating for Taste-Masked Granules – Before and After Tablet Compression

Raman microscopy was used to visualize the integrity of a barrier membrane coating at the various stage of chewable tablets development. The effect of substrate morphology and particle characteristics was found to be important in maintaining the integrity of the coating throughout the process of chewable tablets manufacture. Furthermore, the observations from the Raman image analysis provide an understanding of the factors affecting drug release.

MDA-MB-231 and HeLa cells attachment to nanostructured zein surfaces

Detection and characterization of tumor cells are important for cancer diagnosis and therapy. Various surface attachment methods have been proposed for the capture and enumeration of cancer cells, including immunoaffinity and nanostructured surfaces. Zein, a corn protein, has shown good biocompatibility with human liver cells (HL-7702) and mice fibroblasts (NIH3T3). In previous work, it was found that tissue transglutaminase coated on zein substrates enhanced adhesion and spreading of NIH3T3 fibroblast cells. In the present study, cancer cell adhesion to nanostructured zein substrates was investigated. MDA-MB-231 and HeLa cells were used as cancer cell surrogates. MDA-MB-231 cell immobilization was enhanced on zein films, prepared with 80% ethanol, over glass surfaces. The application of tissue transglutaminase onto nanostructured zein substrates further increased cell spreading and adhesion. Cell immobilization increased linearly with the tissue transglutaminase content of the substrate. The effect of substrate morphology was also investigated by seeding cells on electrospun zein fibers. HeLa cell adhesion was also enhanced by zein substrates. This study provided preliminary supporting evidence for developing a zein platform for circulating tumor cells’ immobilization.

Preparation of Mixed Ionic Electronic Conducting (MIEC) Membrane Supported on Al2O3 Substrate: Effects of Substrate Morphology

Two types of solvents [N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO)] were used in the preparation of alumina (Al2O3) dope suspensions whereby the dope was allowed to experience phase inversion in the coagulation bath. The green body of alumina discs were sintered at 1450°C and the morphologies of prepared alumina-NMP and aluminaDMSO were studied. To improve the catalytic activity of the oxygen transport membrane for oxygen separation purposes, surface modifications of the membranes were carried out using different mixed ionic electronic conducting (MIEC) oxides catalysts (LCF 91 and LSF 55). The oxide powders and viscous sol were synthesised using sol-gel method and calcined at 950°C to form pure perovskite structure of MIEC materials and studied using XRD while the specific surface area of the calcined powder was measured using BET (Brunauer-Emmett-Tellet) technique. The honey-like MIEC sols were used for surface modification and conducted via dip-coating method and the morphology of the surface-modified alumina membranes were analysed using SEM with EDS mapping. From the study, it was found that the amount of MIEC oxide deposited onto alumina-DMSO is higher than alumina-NMP.

Large-area growth of multi-layer hexagonal boron nitride on polished cobalt foils by plasma-assisted molecular beam epitaxy

Two-dimensional (2D) hexagonal boron nitride (h-BN), which has a similar honeycomb lattice structure to graphene, is promising as a dielectric material for a wide variety of potential applications based on 2D materials. Synthesis of high-quality, large-size and single-crystalline h-BN domains is of vital importance for fundamental research as well as practical applications. In this work, we report the growth of h-BN films on mechanically polished cobalt (Co) foils using plasma-assisted molecular beam epitaxy. Under appropriate growth conditions, the coverage of h-BN layers can be readily controlled by growth time. A large-area, multi-layer h-BN film with a thickness of 5~6 nm is confirmed by Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. In addition, the size of h-BN single domains is 20~100 μm. Dielectric property of as-grown h-BN film is evaluated by characterization of Co(foil)/h-BN/Co(contact) capacitor devices. Breakdown electric field is in the range of 3.0~3.3 MV/cm, which indicates that the epitaxial h-BN film has good insulating characteristics. In addition, the effect of substrate morphology on h-BN growth is discussed regarding different domain density, lateral size, and thickness of the h-BN films grown on unpolished and polished Co foils.

Effect of Substrate Morphology on the Odd–Even Effect in Hydrophobicity of Self-Assembled Monolayers

Surface roughness, often captured through root-mean-square roughness (Rrms), has been shown to impact the quality of self-assembled monolayers (SAMs) formed on coinage metals. Understanding the effect of roughness on hydrophobicity of SAMs, however, is complicated by the odd-even effect-a zigzag oscillation in contact angles with changes in molecular length. We recently showed that for surfaces with Rrms > 1 nm, the odd-even effect in hydrophobicity cannot be empirically observed. In this report, we compare wetting properties of SAMs on Ag and Au surfaces of different morphologies across the Rrms ∼ 1 nm limit. We prepared surfaces with comparable properties (grain sizes and Rrms) and assessed the wetting properties of resultant SAMs. Substrates with Rrms either below or above the odd-even limit were investigated. With smoother surfaces (lower Rrms), an inverted asymmetric odd-even zigzag oscillation in static contact angles (θs) was observed with change from Au to Ag. Asymmetry in odd-even oscillation in Au was attributed to a larger change in θs from odd to even number of carbons in the n-alkanethiol and vice versa for Ag. For rougher surfaces, no odd-even effect was observed; however, a gradual increase in the static contact angle was observed. Increase in the average grain sizes (>3 times larger) on rough surfaces did not lead to significant difference in the wetting properties, suggesting that surface roughness significantly dominated the nature of the SAMs. We therefore infer that the predicted roughness-dependent limit to the observation of the odd-even effect in wetting properties of n-alkanethiols cannot be overcome by creating surfaces with large grain sizes for surfaces with Rrms > 1 nm. We also observed that the differences between Au and Ag surfaces are dominated by differences in the even-numbered SAMs, but this difference vanishes with shorter molecular chain length (≤C3).

Adsorption of Alkylthiol Self-Assembled Monolayers on Gold and the Effect of Substrate Roughness: A Comparative Study Using Scanning Tunneling Microscopy, Cyclic Voltammetry, Second-Harmonic Generation, and Sum-Frequency Generation

Self-assembled monolayers (SAMs) of alkylthiols on gold have called considerable attention due to several applications in the modification and control of surface properties, such as wettability, tribology, and biocompatibility. Therefore, understanding the adsorption and molecular structure of these SAMs is crucial to optimize their quality for a given application. Although many studies in this area have been performed, the effects of substrate morphology on the quality of long chain alkylthiols on gold have not been satisfactorily clarified. This study focuses on the adsorption and conformation of SAMs of 1-hexadecanethiol (C16SH) as a function of adsorption time, substrate roughness, and morphology. The adsorption of C16SH on atomically flat Au surfaces was analyzed via cyclic voltammetry (CV), scanning tunneling microscopy (STM), and second-harmonic generation (SHG), while the molecular conformation and orientation were characterized via sum-frequency generation (SFG) vibrational spectroscopy. We show ...

Design and Characterization of Hybrid Morphology Nanoarrays as Plasmonic Raman Probes for Antimicrobial Detection

Advances in nanofabrication have allowed the production of new and more reproducible substrates for the Raman detection of trace antimicrobials in water. The superior substrate uniformity combined with the ability to control surface morphology represents a significant step forward in the design of substrates with improved enhancement factors and trace-detection capabilities. The work presented herein successfully combines electron-beam lithography (EBL) and reactive ion-etching (RIE) protocols for the construction, testing, and validation of plasmonic hybrid morphology nanoarrays for the detection of arsenic antimicrobials in water. The fabricated substrates consist of 2500 μm(2) Ag-coated silicon dioxide (SiO2)/Si pillar nanoarrays of alternating hexagonal and elliptical features. Control of simple fabrication parameters such as inter-particle spacing (gap) and its orientation relative to the laser polarization vector (parallel or orthogonal) result in over a tenfold improvement in the apparent Raman response under optimized conditions. At a 633 nm excitation frequency, the best substrate performance was observed on parallel-oriented features with a 200 nm gap, with over one order of magnitude increase in the apparent surface-enhanced Raman scattering (SERS) signal relative to standard silver-polydimethylsiloxane (Ag-PDMS) nanocomposites. Monitoring of the characteristic As-C stretching band at 594 cm(-1) allowed the detection of arsenic antimicrobials in water well within the parts per million range. Calculated surface-enhancement factors (SEF) for this substrate, employing 532, 785, and 633 nm excitation wavelengths, was within five, six, and seven orders of magnitude, respectively. The effect of substrate morphology and nanofabrication process on the Raman enhancement factor is presented.

Variation in mode II dominated interface fracture of stainless steel–epoxy bonds. Part 2: Multi-scale damage analysis

The fracture at stainless steel–epoxy interfaces is investigated using acoustic emission (AE), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The effects of substrate morphology and aging on the interface are traced. Narrow grooves at the grain boundaries of steel introduce submicron-scale mechanical interlocking and result in high toughness. Sharp ridges after nitric acid etching introduce secondary cracking but may initiate interface collapse. The tough fracture process induced negligible AE. Short-term aging of an interphase region causes diminished secondary cracking and the mechanical interlocking to malfunction.

Effect of substrate morphology on the nucleation and growth of ZnO nanorods prepared by spray pyrolysis

ZnO nanorods were prepared by a spray pyrolysis technique on both as-received and etched Indium Tin Oxide (ITO)/glass substrates. The morphologies of the ITO substrates, the ZnO nucleation mechanism and the development of ZnO nanorods on both types of ITO substrates were investigated by Atomic Force Microscopy and Scanning Electron Microscopy methods. It was found that the amount of nucleation sites on as-received ITO is significantly higher compared to that on the etched ITO. As a result, well-shaped, elongated, strongly c-axis-oriented ZnO nanorods were obtained on the etched ITO/glass substrates. In contrast, randomly oriented ZnO nanocrystals with different shapes and sizes, as well as low aspect ratios, were obtained on the as-received substrates. It was found that ZnO nucleation follows the grain-boundary nucleation mechanism.

Direct Measurements of Contact Force between Clathrate Hydrates and Water

A method for precise and reproducible initial contact force measurements is introduced utilizing an apparatus fabricated with a microbalance and z-axis stage to study the interaction behavior between cyclopentane (CP) hydrate and water in a temperature controlled hydrocarbon environment. CP hydrate probes are prepared using hydrate slurries composed of 5 wt % CP and Wilhelmy rods. The CP hydrate probe is slowly brought into contact with water to determine the initial contact force. The effect of substrate morphology on the initial contact force is reported through employing aluminum substrates prepared using physical vapor deposition (PVD) and milling. Accurate and facile measurements are performed by applying a high-resolution microbalance with 0.1 microN resolution to provide repeatable and consistent results of initial contact force between hydrate and water.

Effects of Substrate Morphology and Postelectrodeposition on Structure of Cu Foam and Their Application for Li-Ion Batteries

The effects of Cu substrate morphology and postelectrodeposition on the porosity and mechanical strength of Cu foam electrodeposits are examined. The porosity of the Cu foam is enhanced by changing the morphology of the Cu substrate from smooth to nodular because bubbles are split into small bubbles by the nodules. In addition, the adhesive properties of the Cu foam deposited on the nodular Cu foil are improved by the mechanical interlocking effects of the nodules. As a result of the postelectrodeposition treatment, the mechanical strength of the Cu foam is significantly enhanced primarily due to the covering of the post-Cu electrodeposit on the dendrite crystallites of the Cu foam. The Li capacity and cycle performances of a Sn anode are clearly improved when Sn is electrodeposited on the covered Cu foam on the nodular Cu foil compared with that on the uncovered Cu foam: at the 30th cycle for the Sn anode formed on the covered Cu foam on a nodular Cu foil and at the 30th cycle for the Sn electrode on the uncovered Cu foam on a smooth Cu foil.

Effects of Substrate Morphology on Cu Foam Prepared by Electrodeposition and their Application for Electrodes of Li-ion Battery

not Available.

Influence of the substrate geometrical parameters on microcrystalline silicon growth for thin-film solar cells

The effect of substrate morphology on the growth and electrical properties of single-junction microcrystalline silicon cells is investigated. A large variety of V-shaped and U-shaped substrates are characterized by scanning electron microscopy (SEM) and the growth of thin-film microcrystalline silicon (μc-Si:H) devices is observed by cross-sectional transmission electron microscopy (TEM). It is shown that enhanced electrical properties of solar cells are obtained when U-shaped substrates are used and the effect is universal, i.e. independent of the substrate or feature size. U-shaped substrates prevent the formation of two dimensional “cracks”, which are identified as zones of porous material, from propagating throughout the active part of the solar cell. A numerical growth simulation program reproduces satisfactorily these experimental observations. According to these simulations, shadowing effect due to surface morphology and low adatom surface diffusion length are responsible for the formation of cracks in μc-Si:H material.