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Thin Coatings (thin + coating)
Selected AbstractsResponsive Coatings: Stimuli-Responsive Thin Coatings Using Elastin-Like Polymers for Biomedical Applications (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Mater. Costa et al. successfully apply a simple protein adsorption technique combining chitosan substrates and recombinant elastin-like polymers (ELPs) on page 3210. This process allows for coating of polysaccharide substrates with such biomimetic macromolecules, resulting in interesting properties such as smart behavior and improved cell adhesion. The figure illustrates symbolically the reversible structural changes that occur to the ELP simply by changing temperature. [source] Stimuli-Responsive Thin Coatings Using Elastin-Like Polymers for Biomedical ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Rui R. Costa Abstract Smart thin coatings using a recombinant elastin-like polymer (ELP) containing the cell attachment sequence arginine,glycine,(aspartic acid) (RGD) are fabricated for the first time through simple deposition of the ELP dissolved in aqueous-based solutions. The biopolymer is produced and characterized using electrophoresis and mass spectroscopy. The temperature and pH responsiveness are assessed by aggregate size measurements and differential scanning calorimetry. The deposition of the studied ELP onto chitosan is followed in situ with a quartz-crystal microbalance with dissipation monitoring (QCM-D). Contact angle measurements are performed at room temperature and at 50,°C, showing reversible changes from a moderate hydrophobic behavior to an extremely wettable surface. AFM analysis performed at room temperature reveals a smooth surface and no organized structure. At 50,°C, the surface presents spherical nanometer-sized structures of collapsed biopolymer chains. Such results suggest that the ELP chains, when collapsed, aggregate into micelle-like structures at the surface of the substrate, increasing its water affinity. Cell adhesion tests on the developed coatings are conducted using a SaOS-2 cell line. Enhanced cell adhesion could be observed in the H-RGD6-coated surfaces, as compared with the original chitosan monolayer. An intermediate behavior is found in chitosan coated with the corresponding ELP without the RGD sequence. Therefore, the developed films have great potential as biomimetic coatings of biomaterials for different biomedical applications, including tissue engineering and controlled delivery of bioactive agents. Their thermo-responsive behavior can also be exploited for tunable cell adhesion and controlled protein adsorption. [source] An Analysis of the Effect of a Vent Hole on Excess Cement Expressed at the Crown,Abutment Margin for Cement-Retained Implant CrownsJOURNAL OF PROSTHODONTICS, Issue 1 2009Dipan Patel BDS Abstract Purpose: The labial margins of anterior implant-retained crowns are often positioned subgingivally for a superior esthetic appearance. One of the consequences of subgingival margins is the increased risk of leaving excess cement behind following cementation. This can lead to potential problems, including peri-implant inflammation, soft tissue swelling, soreness, bleeding or suppuration on probing, and bone loss. The purpose of this laboratory study was to investigate the effect of placement, location, and diameter of a vent hole on the amount of cement being expressed at the margin of an anterior implant abutment-retained crown. Materials and Methods: Three implant crown copings were fabricated to fit on the same custom abutment. Three vent diameters (0.75, 1.25, and 1.65 mm) and three locations on the palatal surface of the coping (cervico-palatally, mid-palatally, inciso-palatally) were chosen for vent hole placement. For each test, the coping was cemented onto the abutment under standardized conditions. A preweighed thin coating of cement was applied to the fit surface of the coping. The amount of cement expressed at the margin and vent hole was measured by weight and calculated as a proportion of the amount of cement placed in the coping before seating. The procedure was completed 15 times for each variable. The results were statistically analyzed using univariate ANOVA with post hoc Bonferroni-adjusted independent samples t -tests. Results: The presence of a vent hole influenced the proportion of cement expressed at the coping margin (p < 0.05). The location of a vent hole influenced the proportion of cement expressed at the coping margin (p < 0.05), with the exception of the mid-palatal and inciso-palatal positioning where there was no significant difference (p= 0.61) between groups. The diameter of the vent hole did not significantly influence the proportion of cement expressed at the coping margin (p= 0.096). Conclusions: When using anterior cement-retained implant crowns, the use of a 0.75-mm mid-palatal or inciso-palatal vent hole to minimize the amount of cement expressed at the margin during cementation should be considered. [source] Chemically Bonded Phosphate Ceramics: II, Warm-Temperature Process for Alumina CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2003Arun S. Wagh This is the second of three papers on a dissolution model that describes the formation of chemically bonded phosphate ceramics. In this paper, we discuss the kinetics of formation of aluminum phosphate ceramics between 100° and 150°C. Using basic thermodynamic formulations, we calculated the temperatures of maximum solubility of alumina and its hydrated phases and predicted the temperatures of formation of ceramics. Differential thermal and X-ray diffraction analyses on samples made in the laboratory confirm these temperatures. The resulting ceramics of alumina bonded with aluminum phosphate (berlinite) show a high compressive strength of 16 000 psi. We have concluded that rapid evaporation of excess water in the slurry generates porosity in the ceramics, and that better processing methods are needed. A consolidation model is presented that describes the microstructure of the ceramic. It predicts that a very small amount of alumina must be converted to form the bonding phase; hence, the product is mostly alumina with a thin coating of berlinite on the surface of alumina particles. [source] Fixation of heavy contaminants of a dirty bomb attack: Studies with uranium and metal simulantsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2007Thomas L. McGehee Abstract Asphalt emulsions were evaluated as a means to immobilize radiological contaminants deposited on urban surfaces after a dirty bomb attack. Contaminated surfaces would be sprayed with thin coatings of asphalt emulsion to encapsulate the radioactive particles until the site can be safely remediated. This research investigated applications of an asphalt emulsion (Topein C, Encapco Technologies, LLC, Napa, CA) to treat (zero-valent) iron, lead, and uranium powders on various building material surfaces. Initial studies found that some of the building materials (limestone, concrete, and metal) reacted with the emulsion producing gas bubbles, which formed 0.001 to 1 cm vesicles in the cured asphalt emulsion. These vesicles, however, did not expose the building material surface, and the reaction appeared to aid in the setting of the emulsion. Powdered lead did not react with the asphalt emulsion, but iron powder and uranium did. Iron powder and the emulsion formed vesicles up to 0.5 mm (but not exposing the building material surface), while the uranium (U3O8) had a moderate reaction when compared with to the lead and iron powders. Scanning electron micrographs showed that the lead powder formed nonreactive layers adjacent to the concrete surface while iron particles were evenly distributed in the asphalt matrix due to the reaction with the asphalt, indicating that the physical and chemical reactions between the iron metal particles, asphalt, and concrete affected particle distribution in the asphalt matrix. A vertical operation sediment tube was used to determine the flowing shear stress durability of the asphalt/metal/substrate complex. The asphalt treatment with iron had no loss at the shear range tested (0.1,2.5 Pa), while the asphalt stabilized powdered lead lost 8% asphalt and lead at 2.5 Pa mean shear stress applied for 5 h. The chemical reaction between asphalt emulsion and iron increased the resistance of the asphalt/metal/substrate complex to shear when compared with lead. Some hydrogen was formed in reactions with iron, but the amount formed was well below the lower flammability limit. Treatment of uranium indicated that the emulsion was effective at reducing leaching of the uranium 10 fold. These experiments indicate that asphalt emulsions may be a viable means for containing metallic or dense radiological contaminants on common building materials. © 2007 American Institute of Chemical Engineers Environ Prog 26:94,103, 2007 [source] Nanotechnology Applied on Hot Forging DiesADVANCED ENGINEERING MATERIALS, Issue 7 2008H.-C. The life time of the forging dies still remains a concern and plays an important role on the costs of this process. Latest developments achieved with nanotechnology have proven that thin coatings applied on the surface of the hot forging dies bring technical and economical gains. PVD (Physical Vapor Deposition) deposition processes have confirmed their potential to substantially improve the wear resistance of the hot forging dies. [source] Conformal Nano-Sized Inorganic Coatings on Mesoporous TiO2 Films for Low-Temperature Dye-Sensitized Solar Cell FabricationADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Larissa Grinis Abstract Here, a new method based on sol,gel electrophoretic deposition to produce uniform high-quality inorganic conformal coatings on mesoporous nano-particulate films is presented. This novel sol preparation method allows for very fine control of the coating properties, thus inducing new adjustable functionalities to these electrodes. It is shown that the deposition of an amorphous TiO2 and/or MgO shell onto photoanodes used in dye-sensitized solar cells (DSSCs) improves their light-to-electric-power conversion efficiency without the need for sintering. It is proposed that the amorphous TiO2 coating improves the electronic inter-particle connection and passivates the surface states. The insulating MgO coating further reduces the electron transfer from the conduction band into the electrolyte while the electron injection from the excited dye state remains unperturbed for thin coatings. Using a low-temperature method for DSSC production on plastic substrates, a maximum efficiency of 6.2% applying pressure together with an optimized TiO2 coating is achieved. For systems that cannot be pressed a conversion efficiency of 5.1% is achieved using a double shell TiO2/MgO coating. [source] Stimuli-Responsive Thin Coatings Using Elastin-Like Polymers for Biomedical ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Rui R. Costa Abstract Smart thin coatings using a recombinant elastin-like polymer (ELP) containing the cell attachment sequence arginine,glycine,(aspartic acid) (RGD) are fabricated for the first time through simple deposition of the ELP dissolved in aqueous-based solutions. The biopolymer is produced and characterized using electrophoresis and mass spectroscopy. The temperature and pH responsiveness are assessed by aggregate size measurements and differential scanning calorimetry. The deposition of the studied ELP onto chitosan is followed in situ with a quartz-crystal microbalance with dissipation monitoring (QCM-D). Contact angle measurements are performed at room temperature and at 50,°C, showing reversible changes from a moderate hydrophobic behavior to an extremely wettable surface. AFM analysis performed at room temperature reveals a smooth surface and no organized structure. At 50,°C, the surface presents spherical nanometer-sized structures of collapsed biopolymer chains. Such results suggest that the ELP chains, when collapsed, aggregate into micelle-like structures at the surface of the substrate, increasing its water affinity. Cell adhesion tests on the developed coatings are conducted using a SaOS-2 cell line. Enhanced cell adhesion could be observed in the H-RGD6-coated surfaces, as compared with the original chitosan monolayer. An intermediate behavior is found in chitosan coated with the corresponding ELP without the RGD sequence. Therefore, the developed films have great potential as biomimetic coatings of biomaterials for different biomedical applications, including tissue engineering and controlled delivery of bioactive agents. Their thermo-responsive behavior can also be exploited for tunable cell adhesion and controlled protein adsorption. [source] Bio-hybrid nanocomposite coatings from sonicated chitosan and nanoclayJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Jari Vartiainen Abstract Nanocomposite films and coatings with improved properties were produced from ultrasonic dispersed chitosan and hydrophilic bentonite nanoclay. Bio-hybrid coatings were applied onto argon,plasma-activated LDPE coated paper. The intercalation of chitosan in the silicate layers was confirmed by the decrease of diffraction angles as the chitosan/nanoclay ratio increased. Nanocomposite films and multilayer coatings had improved barrier properties against oxygen, water vapor, grease, and UV-light transmission. Oxygen transmission was significantly reduced under all humidity conditions. In dry conditions, over 99% reduction and at 80% relative humidity almost 75% reduction in oxygen transmission rates was obtained. Hydrophilic chitosan was lacking the capability of preventing water vapor transmission, thus total barrier effect of nanoclay containing films was not more than 15% as compared with pure chitosan. Because to very thin coatings (,1 ,m), nanoclay containing chitosan did not have antimicrobial activity against test strains. All coating raw materials were "generally recognized as safe" (GRAS) and the calculated total migration was in all cases ,6 mg/dm2, thus the coatings met the requirements set by the packaging legislation. Processing of the developed bio-hybrid nanocomposite coated materials was safe as the amounts of released particles under rubbing conditions were comparable with the particle concentrations in a normal office environment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] | ||||||||||