Types Of Surface Modifications Research Articles

Mechanical and morphological study of polymer composite plates having different fiber surface treatments with particular response to high velocity projectile impact

This study investigates morphological and mechanical behaviors of polymer composite plates reinforced with surface modified glass fiber woven roving with special interest in high velocity impact response. Four types of surface modification were applied to the glass fiber surface, namely: virgin fabric (silane coupling agent removed), silane-treated (as received fabric), corona-treated virgin fabric and silane- plus corona-treated fabric. Hand layup technique was adopted to make composite plates with [0/90, ±452, 0/90] layup using unsaturated polyester resin as matrix. Mechanical testing methods, such as tensile and bending loading as well as low velocity Izod impact and high velocity impact tests in velocities of 88.5, 108.3 and 144 m/s were conducted. The results showed that, although in lower part of high velocity impact rates, i.e., 88.5 m/s, the panels with fiber fabric treatment of silane plus corona revealed significant increase in ballistic resistance, but in general, it was found that the order of optimum performance for E-glass fiber woven roving surface modification methods are: silane, silane plus corona treatment, virgin fabric and sole corona treatment, respectively. The results further revealed that at impact velocities of 108.3 and 144 m/s, the energy absorptions for the samples with silane treatment are 7.9 and 6.6% higher compared to the samples with silane plus corona discharge treatment (S + C) samples, respectively. Damage assessment revealed higher damage extension in the samples with fiber having silane plus corona discharge treatment. Morphological studies on surface roughness were conducted by SEM analysis. The results correlated well with mechanical and impact results in those samples with higher surface roughness showed better mechanical performance and that silane treatment was the dominant factor in performance.

Deuterium trapping and surface modification of polycrystalline tungsten exposed to a high-flux plasma at high fluences

Deuterium (D) retention and surface modifications of hot-rolled polycrystalline tungsten (W) exposed to a low-energy (~40 eV D−1), high-flux (2–5 × 1023 D m−2 s−1) D plasma at temperatures of ~380 K and ~1140 K to fluences up to 1.2 × 1028 D m−2 have been examined by using nuclear reaction analysis, thermal desorption spectroscopy, and scanning electron microscopy. The samples exposed at ~380 K exhibited various types of surface modifications: dome-shaped blister-like structures, stepped flat-topped protrusions, and various types of nanostructures. It was observed that a large fraction of the surface was covered with blisters and protrusions, but their average size and the number density showed almost no fluence dependence. The D depth distributions and total D inventories also barely changed with increasing fluence at ~380 K. A substantial amount of D was retained in the subsurface region, and thickness correlated with the depth where the cavities of blisters and protrusions were located. It is therefore suggested that defects appearing during creation of blisters and protrusions govern the D trapping in the investigated fluence range. In addition, a large number of small cracks was observed on the exposed surfaces, which can serve as fast D release channels towards the surface, resulting in a reduction of the effective D influx into the W bulk. On the samples exposed at ~1140 K no blisters and protrusions were found. However, wave-like and faceted terrace-like structures were formed instead. The concentrations of trapped D were very low (<10−5 at. fr.) after the exposure at ~1140 K.

Surface modification of Ti6Al4 V implants by heat, H2O2 and alkali treatments

In the present research we have applied three types of surface modifications on Ti6Al4 V alloy including heat treatment, H2O2 treatment and alkali treatment. Scanning electron microscope and thin-film X-ray diffractometry (TF-XRD) were used to analyse the surface structure and the formed phases on the surface modified specimens. In vitro bioactivity evaluations were carried out and the cytocompatibility assay was performed using the evaluation of viability and attachment of L-929 fibroblast cells. The results revealed more bioactivity of the alkali-treated Ti6Al4 V alloy compared to other surface modifications. Better cellular response was also observed on the alkali-treated specimens. According to the results of our study, alkali treatment enhanced the in vitro bioactivity and cytocompatibility of Ti6Al4 V alloy more effectively than H2O2 treatment and heat treatment.

Superparamagnetic iron oxide nanoparticles as a multimodal contrast agent for up to five imaging modalities

labeled nanometer sized colloids are injected sub-dermally or peri-tumourally, and then imaged using a gamma camera/SPECT (before surgery) and a gamma probe (during surgery). A blue dye injected prior to surgery may serve to visualize the SLN intra-operatively. When the SLN is found, it is removed by invasive surgery and cancer infiltration is examined using histology. The lack of precise anatomic information in the scintigraphic images and the non-specificity of the tracer, however, often limit the preoperative planning and the identification of the SLN. Multimodal approaches in the clinic, such as the next generation hybrid systems based on combined MR/PETsystems, are expected to address several of these issues. In the pre-clinical setting, an even faster growing segment for medical imaging‐multimodal systems including optical methods is concurrently emerging. Interestingly, there exist still no commercially available clinical contrast agent that can be used for even two modalities, and research has shown functionality for only a couple imaging modalities at a time. Our aim is to develop novel multimodality contrast agents and methodology for such systems to meet new needs for quantitative and high-resolution imaging. In this perspective, superparamagnetic iron oxide nanoparticles (SPIO-NPs) are emerging as a highly attractive approach. SPIO-NPs can be observed by MRI as signal voids in the MR image and SPIO-NPs have been approved as MRI contrast agents for more than a decade with applications including lymph node detection. We propose the use of SPIO-NPs as a multimodal contrast agent by attaching radionuclides and fluorophores to the surface of the nanoparticles, for, respectively, SPECT, PET, and optical imaging methods. Moreover, the particles also inherently functions as contrast media for a new imaging technique called magnetomotive ultrasound imaging. Thus, the very same particles can be used as a contrast agent for up to five modalities, depending on the type of surface modification. We expect the following improvements for the work-flow of cancer patients undergoing lymph node surgery: • One single injection of tracer, and thereby no timing issues experienced with the dye used today. This means less preparation time prior to surgery, and reduced risk of lymph edema due to excessive removal of colored lymph nodes. • Improved staging due to truly combined information in a PET/MR system including tracer migration analysis.

Water dispersible upconverting nanoparticles: effects of surface modification on their luminescence and colloidal stability.

We present a systematic study on the effect of surface ligands on the luminescence properties and colloidal stability of β-NaYF4:Yb(3+),Er(3+) upconversion nanoparticles (UCNPs), comparing nine different surface coatings to render these UCNPs water-dispersible and bioconjugatable. A prerequisite for this study was a large-scale synthetic method that yields ∼2 g per batch of monodisperse oleate-capped UCNPs providing identical core particles. These ∼23 nm sized UCNPs display an upconversion quantum yield of ∼0.35% when dispersed in cyclohexane and excited with a power density of 150 W cm(-2), underlining their high quality. A comparison of the colloidal stability and luminescence properties of these UCNPs, subsequently surface modified with ligand exchange or encapsulation protocols, revealed that the ratio of the green (545 nm) and red (658 nm) emission bands determined at a constant excitation power density clearly depends on the surface chemistry. Modifications relying on the deposition of additional (amphiphilic) layer coatings, where the initial oleate coating is retained, show reduced non-radiative quenching by water as compared to UCNPs that are rendered water-dispersible via ligand exchange. Moreover, we could demonstrate that the brightness of the upconversion luminescence of the UCNPs is strongly affected by the type of surface modification, i.e., ligand exchange or encapsulation, yet hardly by the chemical nature of the ligand.

Interphase evolution at two promising electrode materials for Li-ion batteries: LiFePO4 and LiNi1/2 Mn1/2O2.

The present review reports the characterization and control of interfacial processes occurring on olivine LiFePO(4) and layered LiNi(1/2) Mn(1/2)O(2), standing here as model compounds, during storage and electrochemical cycling. The formation and evolution of the interphase created by decomposition of the electrolyte is investigated by using spectroscopic tools such as magic-angle-spinning nuclear magnetic resonance ((7)Li,(19)F and (31)P) and electron energy loss spectroscopy, in parallel to X-ray photoelectron spectroscopy, to quantitatively describe the interphase and unravel its architecture. The influence of the pristine surface chemistry of the active material is carefully examined. The importance of the chemical history of the surface of the electrode material before any electrochemical cycling and the strong correlation between interface phenomena, the formation/evolution of an interphase, and the electrochemical behavior appear clearly from the use of these combined characterization probes. This approach allows identifying interface aging and failure mechanisms. Different types of surface modifications are then investigated, such as intrinsic modifications upon aging in air or methods based on the use of additives in the electrolyte or carbon coatings on the surface of the active materials. In each case, the species detected on the surface of the materials during storage and cycling are correlated with the electrochemical performance of the modified positive electrodes.

Simulation of chemical modification of polymer surface

The mathematical model describing chemical interaction of a polymer film with a reagent gas is developed. This model allows for significant changes in the chemical composition, structure, and physicochemical properties of the polymer as a result of modification. For certain types of surface modification, such as fluorination, a number of limitations and assumptions may be drawn that make it possible to perform the analytical solution of equations which are used as a basis to calculate the depths and profiles of equal fluorination degrees for various amorphous–crystalline polymers. The results of calculations of fluorination degrees conducted within the framework of the model are in fairly good agreement with the experimental data. The effects of surface layer transformed via fluorination on certain important characteristics of films and articles manufactured from polyethylene of various brands are revealed. These effects include increase in the chemical resistance of pipes, decrease in their permeability for low-molecular-mass compounds, reduction in fuel penetration of fuel tanks, and improvement in the thermal compatibility of films.

Theoretical Study of the Energetic Stability and Geometry of Terminated and B-Doped Diamond (111) Surfaces.

The effect of B doping on the surface (111) reactivity has, in the present study, been investigated for various surface terminations, H, OH, Oon-top, and F. This type of surface modification has experimentally been proven to be extremely important for, for example, applications based on surface electrochemistry. Density functional theory (DFT) has here been used to study both the local and more global effects of substitutionally positioned B atoms in the upper part of the diamond (111) surface. For this purpose, adsorption energies for the various terminating species have been calculated, and the observed results have been carefully analyzed in order to gain a deeper knowledge about the atomic-level cause of the observed effects. As a result, the B dopant shows a clear, but local, effect for all terminating species investigated. In addition, it is only the radical O-terminating species that show a special and high reactivity on the diamond surface. The other terminating species show a much lower reactivity, which in addition are very similar.

Electrophoretic Deposition of Carbon Nanotubes over TiO2 Nanotubes: Evaluation of Surface Properties and Biocompatibility.

Titanium (Ti) is often used as an orthopedic and dental implant material due to its better mechanical properties, corrosion resistance, and excellent biocompatibility. Formation of TiO2 nanotubes (TiO2 NTs) on titanium is an interesting surface modification to achieve controlled drug delivery and to promote cell growth. Carbon nanotubes (CNTs) possess excellent chemical durability and mechanical strength. The use of CNTs in biomedical applications such as scaffolds has received considerable attention in recent years. The present study aims to modify the surface of titanium by anodizing to form TiO2 NTs and subsequently deposit CNTs over it by electrophoretic deposition (EPD). Characteristic, biocompatibility, and apatite forming ability of the surface modified samples were evaluated. The results of the study reveal that CNTs coating on TiO2 nanotubes help improve the biological activity and this type of surface modification is highly suitable for biomedical applications.

Enhanced modification of tungsten surface by nanostructure formation during high flux deuterium plasma exposure

The morphology changes induced by low energy deuterium ions on tungsten surfaces is studied for particle fluxes similar to those expected in the ITER divertor, as high as 1024m−2s−1. A new type of surface modifications by formation of nanostructures is observed to occur under those conditions. The nanostructures formation is critically dependent on the particle flux and ion energy, and affected by surface temperature and particle fluence. It correlates with the formation of nano-cavities at a depth of about 40nm below the surface. In addition, the positron annihilation Doppler broadening (PADB) measurements reveal a significant increase of defect concentration (mostly vacancy-type) after plasma exposure, and the evolution of defects is in line with the surface morphology changes with fluence and surface temperature. The possible mechanism of cyclic trap mutation and dislocation loop punching due to high flux D exposure is discussed.

Relationship between Laser Parameters - Microstructural Modification - Mechanical Properties of Laser Surface Melted Magnesium Alloy AZ91D

Laser surface melting is a high-energy surface treatment that allows modification of the microstructure and surface properties of Mg alloys. In the present work, a high-power diode laser has been used to study the microstructural and mechanical modifications that occur when laser surface treatments are applied to the surface of the AZ91D Mg alloy. Laser-beam power in a range of 375-600 W and laser scanning speeds of 45-60-90 mms-1 has been used to develop a range of laser surface melting treatments. By controlling the laser parameters, two types of surface modifications can be obtained. Complete laser surface melting takes place at high laser input energies whilst at low laser input energies, selective laser surface melting occurs with modification of only one phase in the microstructure of the alloy; the other phase remained unaffected. In terms of mechanical properties, the microstructural modifications introduced by the laser surface treatment implied a hardness homogenization along the melted region.

Nanostructures and hydrophilicity influence osseointegration: a biomechanical study in the rabbit tibia

Implant surface properties have long been identified as an important factor to promote osseointegration. The importance of nanostructures and hydrophilicity has recently been discussed. The aim of this study was to investigate how nanostructures and wettability influence osseointegration and to identify whether the wettability, the nanostructure or both in combination play the key role in improved osseointegration. Twenty-six adult rabbits each received two Ti grade 4 discs in each tibia. Four different types of surface modifications with different wettability and nanostructures were prepared: hydrophobic without nanostructures (SLA), with nanostructures (SLAnano); hydrophilic with two different nanostructure densities (low density: pmodSLA, high density: SLActive). All four groups were intended to have similar chemistry and microroughness. The surfaces were evaluated with contact angle measurements, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and interferometry. After 4 and 8weeks healing time, pull-out tests were performed. SLA and SLAnano were hydrophobic, whereas SLActive and pmodSLA were super-hydrophilic. No nanostructures were present on the SLA surface, but the three other surface modifications clearly showed the presence of nanostructures, although more sparsely distributed on pmodSLA. The hydrophobic samples showed higher carbon contamination levels compared with the hydrophilic samples. After 4weeks healing time, SLActive implants showed the highest pull-out values, with significantly higher pull-out force than SLA and SLAnano. After 8weeks, the SLActive implants had the highest pull-out force, significantly higher than SLAnano and SLA. The strongest bone response was achieved with a combination of wettability and the presence of nanostructures (SLActive).

Wettability and photocatalysis of CF4 plasma etched titania films of honeycomb structure

Abstract We prepared titania films by aerosol deposition (AD), in which titania powder is supersonically accelerated for deposition onto a substrate. These AD titania films exhibited hydrophilicity and photocatalysis under UV exposure. However, after surface modification by CF 4 plasma-etching, the films showed higher hydrophilicity and lower photocatalytic effect. After sufficient modification, they exhibited superhydrophilicity, which was induced by the presence of fluorine. This type of surface modification is useful for promoting hydrophilicity under no UV light exposure.

Space weathered rims found on the surfaces of the Itokawa dust particles

AbstractOn the basis of observations using Cs‐corrected STEM, we identified three types of surface modification probably formed by space weathering on the surfaces of Itokawa particles. They are (1) redeposition rims (2–3 nm), (2) composite rims (30–60 nm), and (3) composite vesicular rims (60–80 nm). These rims are characterized by a combination of three zones. Zone I occupies the outermost part of the surface modification, which contains elements that are not included in the unchanged substrate minerals, suggesting that this zone is composed of sputter deposits and/or impact vapor deposits originating from the surrounding minerals. Redeposition rims are composed only of Zone I and directly attaches to the unchanged minerals (Zone III). Zone I of composite and composite vesicular rims often contains nanophase (Fe,Mg)S. The composite rims and the composite vesicular rims have a two‐layered structure: a combination of Zone I and Zone II, below which Zone III exists. Zone II is the partially amorphized zone. Zone II of ferromagnesian silicates contains abundant nanophase Fe. Radiation‐induced segregation and in situ reduction are the most plausible mechanisms to form nanophase Fe in Zone II. Their lattice fringes indicate that they contain metallic iron, which probably causes the reddening of the reflectance spectra of Itokawa. Zone II of the composite vesicular rims contains vesicles. The vesicles in Zone II were probably formed by segregation of solar wind He implanted in this zone. The textures strongly suggest that solar wind irradiation damage and implantation are the major causes of surface modification and space weathering on Itokawa.

Novel laser surface treatments on AZ91 magnesium alloy

Laser surface melting is a high-energy surface treatment that allows modification of the microstructure and surface properties of Mg alloys, among many others. In the present work, a high-power diode laser has been used to study the microstructural and mechanical modifications that occur when laser surface treatments are applied to the surface of the AZ91D Mg alloy. By controlling the laser parameters, two types of surface modifications can be obtained. Complete laser surface melting takes place at high input laser energies. At lower input laser energies, selective laser surface melting occurs with modification of only one phase in the microstructure of the alloy; the other phases remain unaffected. These treatments yield different microstructures, imbuing the treated surface with different properties.

Lighting the path: photopatternable substrates for biological applications

Photolithographic patterning methods provide a versatile way of functionalizing substrates for biological and biosensing applications. Here, we provide an overview of recent developments in photopatterning for biological applications. This review emphasizes photopatterned self-assembled monolayers (SAMs) since they have distinguished themselves as a facile means to functionalize a variety of substrates from oxides to noble metals, while also providing precise control over the surface chemistry. These patterning techniques have been divided into four categories depending on the type of surface modification; complete monomer removal, backbone cleavage, tail group degradation, and functional group modification. Additionally, insights are provided into the next generation of patterned substrates for biological applications.

Observations of surface modifications induced by the multiple pulse irradiation using a soft picosecond x-ray laser beam

To study the interactions between picosecond soft x-ray laser (SXRL) beams and material surfaces, gold (Au), copper (Cu), and silicon (Si) surfaces were irradiated with SXRL pulses having a wavelength of 13.9 nm and a duration of ∼7 ps. Following irradiation, the surfaces of the substrates were observed using a scanning electron microscope and an atomic force microscope. With single pulse irradiation, ripple-like structures were formed on the Au and Cu surfaces. These structures were different from previously investigated conical structures formed on an Al surface. In addition, it was confirmed that the development of modified structures, i.e., growth of hillocks on the Au and Cu surfaces, was observed after multiple SXRL pulse exposures. However, on the Si surface, deep holes that seemed to be melted structures induced by the accumulation of multiple pulses of irradiations were found. Therefore, it was concluded that SXRL beam irradiation of various material surfaces causes different types of surface modifications, and the changes in the surface behaviors are attributed to the differences in the elemental properties, such as the attenuation length of x-ray photons.

Glassy Carbon Electrodes Film‐Modified with Acidic Functionalities. A Review

AbstractThis review addresses recent advances in the field of glassy carbon electrodes film‐modified by acidic functionalities. Attention was posed at the architecture of the functionalizing surface film and at practical applications of the relevant sensors. To facilitate the reading, some summarizing tables were included, each one regarding a certain type of surface modification. A final section is aimed at detailing some remarks emerging from the analysis of the reviewed matter. This allowed highlighting the potentialities of the examined sensors, and evidencing some criticisms about how some of their performances were presented in the relevant papers.

Transport of two metal oxide nanoparticles in saturated granular porous media: Role of water chemistry and particle coating

The growing use of nanosized titanium dioxide (nTiO2) and zinc oxide (nZnO) in a large number of commercial products raises concerns regarding their release and subsequent mobility in natural aquatic environments. Laboratory-scale sand-packed column experiments were conducted with bare and polymer-coated nTiO2 and nZnO to improve our understanding of the mobility of these nanoparticles in natural or engineered water saturated granular systems. The nanoparticles are characterized over a range of environmentally relevant water chemistries using multiple complimentary techniques: dynamic light scattering, nanoparticle tracking analysis, transmission electron microscopy, and scanning electron microscopy. Overall, bare (uncoated) nanoparticles exhibit high retention within the water saturated granular matrix at solution ionic strengths (IS) as low as 0.1 mM NaNO3 for bare nTiO2 and 0.01 mM NaNO3 for bare nZnO. Bare nTiO2 and nZnO also display dynamic (time-dependent) deposition behaviors under selected conditions. In contrast, the polymer-coated nanoparticles are much less likely to aggregate and exhibit significant transport potential at IS as high as 100 mM NaNO3 or 3 mM CaCl2. These findings illustrate the importance of considering the extent and type of surface modification when evaluating metal oxide contamination potential in granular aquatic environments.

The adhesion of oral bacteria to modified titanium surfaces: role of plasma proteins and electrostatic forces

Modifications of titanium (Ti) implant surfaces have a significant effect on early biofilm formation and the outcome of implant procedures. The aim of this study was to examine the role of plasma proteins and electrostatic forces in the adhesion mechanism of oral bacteria to modified Ti surfaces. Ti discs with three different types of surface modifications, machined, acid-etched, and acid-etched and blasted, were examined for adhesion of oral bacteria: Streptococcus mutans, Porphyromonas gingivalis, and Fusobacterium nucleatum. Following pretreatment of the Ti with ion rich solutions or coating by human serum albumin or fibronectin, bacterial adhesion was examined by scanning electron microscopy and assessed quantitatively by DNA analysis. Ti coating by proteins as well as bacterial adhesion and their interrelationships were further investigated through confocal scanning laser microscopy. Acid-etched and blasted Ti surfaces exhibited significantly higher amounts of bacteria adhesion than the other two surfaces. Calcium was found to serve as a bridging agent in the adhesion process of S. mutans and F. nucleatum to Ti surfaces. Although albumin coating of the Ti reduced the adhesion of S. mutans to all surfaces, it had no influence on the adhesion of P. gingivalis or F. nucleatum. Coating the Ti with fibronectin enhanced P. gingivalis and F. nucleatum adhesion. Bacterial adhesion to Ti surfaces is roughness-dependent, and the adhesion mechanism is influenced by ions and proteins of the initial coating derived from the blood.