Processing of Ca-P Ceramics, Surface Characteristics and Biological Performance

Bioceramic coatings on metallic implants provide a wear-resistant and biocompatible layer, that own ability to develop bone-like apatite in physiological environments to ensure bonding with hard tissues. These bioceramics primarily belong to Calcium Phosphates (CaPs), bioactive glasses, and glass-ceramics. Several techniques are used to deposit these coatings such as; electrophoretic deposition (EPD), plasma spray (PS), and Radio frequency magnetron sputtering (RFMS). Most of these techniques require a high-temperature operation or sintering treatment. This causes either thermal decomposition of bioceramic or results in delamination and cracking of the bioceramic coating due to differences in thermal expansion behavior of metals and bioceramics. RFMS is primarily carried out either at room temperature. However, annealing is performed or substrate is heated at various temperatures ∼400–1,200°C for 2 or 4 h under dry argon (very low temperature compared to other techniques) to ensure crystallization of bioceramics and improve coating adhesion. Chemical composition stability and excellent surface finish are the premium features of RFMS, due to less heat involvement. Moreover, RFMS has the unique ability to develop one-unit/ multilayered composite coatings and the flexibility of in-situ reactions to yield oxides and nitrides. Single or multiple targets can be employed with the insertion of Oxygen and Nitrogen to yield versatile coatings. Due to this attractive set of features RFMS has a strong potential in the field of bioceramic coatings. In recent years, several multifunctional bioceramic coatings have been deposited on metallic substrates using RFMS for biomedical applications. This review focuses on the recent efforts made in order to deposit multifunctional bioceramic RFMS coatings with surface characteristics necessary for biomedical applications and highlights future directions for the improved biological performance of RFMS bioceramic coatings.

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Medial Smooth Muscle Cell Proliferation in the Balloon Injured Rabbit Aorta: Effect of a Thiazole Compound with Platelet Inhibitory Activity

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661024 ◽

1984 ◽

Vol 51 (01) ◽

pp. 075-078 ◽

Cited By ~ 8

Author(s):

R G Schaub ◽

C A Simmons

Keyword(s):

Smooth Muscle ◽

Platelet Aggregation ◽

Balloon Catheter ◽

Rabbit Aorta ◽

Surface Characteristics ◽

Inhibitory Effect ◽

Lesion Size ◽

Blue Staining ◽

Morphologic Characteristics ◽

Time Period

SummaryTwenty-seven adult male New Zealand rabbits (3–4 kgs) were used in this study. Six rabbits received vehicle, 3 groups of 6 each received doses of 4,5-bis(p-methoxyphenyl)-2-(trifluoromethyl)- thiazole, (U-53,059), at 0.3 mg/kg, 3.0 mg/kg and 30.0 mg/kg/day respectively. Drug and vehicle doses were given orally each day starting 3 days before balloon injury and continuing for the entire 2 week time period. Three rabbits were used as nontreated sham controls. In the vehicle and U-53,059 treated groups aortae were denuded of endothelial cells by balloon catheter injury. Two weeks after injury platelet aggregation to collagen was measured and the aortae removed for analysis of surface characteristics by scanning electron microscopy and lesion size by morphometry. All doses of U-53,059 inhibited platelet aggregation. The 3.0 and 30.0 mg/kg groups had the greatest inhibitory effect. All balloon injured aortae had the same morphologic characteristics. All vessels had similar extent and intensity of Evan’s blue staining, similar areas of leukocyte/platelet adhesion, and a myointimal cell cover of transformed smooth muscle cells. The myointimal proliferative response was not inhibited at any of the drug doses studied.

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Photocatalytic activity of TiO2 synthesized by anodization and anodic spark deposition

MRS Advances ◽

10.1557/adv.2020.405 ◽

2020 ◽

Vol 5 (61) ◽

pp. 3141-3152

Author(s):

Alma C. Chávez-Mejía ◽

Génesis Villegas-Suárez ◽

Paloma I. Zaragoza-Sánchez ◽

Rafael Magaña-López ◽

Julio C. Morales-Mejía ◽

...

Keyword(s):

Electron Microscopy ◽

Photocatalytic Activity ◽

Surface Characteristics ◽

Amorphous Solids ◽

X Ray Diffraction ◽

X Ray ◽

Catalytic Activities ◽

Anodic Spark Oxidation ◽

Porous Surfaces ◽

Scanning Electron

AbstractSeveral photocatalysts, based on titanium dioxide, were synthesized by spark anodization techniques and anodic spark oxidation. Photocatalytic activity was determined by methylene blue oxidation and the catalytic activities of the catalysts were evaluated after 70 hours of reaction. Scanning Electron Microscopy and X Ray Diffraction analysis were used to characterize the catalysts. The photocatalyst prepared with a solution of sulfuric acid and 100 V presented the best performance in terms of oxidation of the dye (62%). The electric potential during the synthesis (10 V, low potential; 100 V, high potential) affected the surface characteristics: under low potential, catalyst presented smooth and homogeneous surfaces with spots (high TiO2 concentration) of amorphous solids; under low potential, catalyst presented porous surfaces with crystalline solids homogeneously distributed.

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Soft Tissue Responses and Attachment to Porous Titanium with Different Surface Characteristics

Journal of Porous Media ◽

10.1615/jpormedia.v9.i2.30 ◽

2006 ◽

Vol 9 (2) ◽

pp. 127-134

Author(s):

Yao Wu ◽

Hu Li ◽

Tun Yuan ◽

Chunlin Deng ◽

Bangcheng Yang ◽

...

Keyword(s):

Soft Tissue ◽

Surface Characteristics ◽

Porous Titanium ◽

Tissue Responses

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Rubber–Road Contact: Comparison of Physics-Based Theory and Indoor Experiments

Tire Science and Technology ◽

10.2346/tire.16.440303 ◽

2016 ◽

Vol 44 (3) ◽

pp. 150-173 ◽

Cited By ~ 5

Author(s):

Mehran Motamedi ◽

Saied Taheri ◽

Corina Sandu

Keyword(s):

Rough Surface ◽

Practical Importance ◽

Surface Profile ◽

Surface Characteristics ◽

Mechanical Analysis ◽

Friction Model ◽

Rubber Friction ◽

Optical Profilometer ◽

Viscoelastic Modulus ◽

Longitudinal Slip

ABSTRACT For tire designers, rubber friction is a topic of pronounced practical importance. Thus, development of a rubber–road contact model is of great interest. In this research, to predict the effectiveness of the tread compound in a tire as it interacts with the pavement, the physics-based multiscale rubber-friction theories developed by B. Persson and M. Klüppel were studied. The strengths of each method were identified and incorporated into a consolidated model that is more comprehensive and proficient than any single, existing, physics-based approach. In the present work, the friction coefficient was estimated for a summer tire tread compound sliding on sandpaper. The inputs to the model were the fractal properties of the rough surface and the dynamic viscoelastic modulus of rubber. The sandpaper-surface profile was measured accurately using an optical profilometer. Two-dimensional parameterization was performed using one-dimensional profile measurements. The tire tread compound was characterized via dynamic mechanical analysis. To validate the friction model, a laboratory-based, rubber-friction test that could measure the friction between a rubber sample and any arbitrary rough surface was designed and built. The apparatus consisted of a turntable, which can have the surface characteristics of choice, and a rubber wheel in contact with the turntable. The wheel speed, as well as the turntable speed, could be controlled precisely to generate the arbitrary values of longitudinal slip at which the dynamic coefficient of friction was measured. The correlation between the simulation and the experimental results was investigated.

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Effect of Polymer, Road Surface, and Driving Conditions on Wear Surface Characteristics of Tire Treads

Tire Science and Technology ◽

10.2346/1.2167171 ◽

1973 ◽

Vol 1 (4) ◽

pp. 354-362 ◽

Cited By ~ 2

Author(s):

F. R. Martin ◽

P. H. Biddison

Keyword(s):

Wear Surface ◽

Surface Characteristics ◽

Road Surface ◽

The Other ◽

Mechanical Degradation ◽

Textured Surface ◽

Test Track ◽

Driving Conditions ◽

Styrene Butadiene ◽

Cylindrical Particles

Abstract Treads made with emulsion styrene-butadiene copolymer (SBR), solution SBR, polybutadiene (BR), and a 60/40 emulsion SBR/BR mixture were built as four-way tread sections on G78-15 belted bias tires, which were driven over both concrete and gravel-textured highways and on a small, circular, concrete test track. The tires were front mounted. When driven on concrete highway, all except the BR tread had either crumbled- or liquid-appearing surfaces, thought to have been formed by mechanical degradation or fatigue. When cornered on concrete, these materials formed small cylindrical particles or rolls. The BR tread had a smooth, granular-textured surface when driven on concrete highway and a ridge or sawtooth abrasion pattern when cornered on concrete. All the materials appeared rough and torn when run on gravel-textured highway. The differences in wear surface formed on BR tread and the other three are thought to be due primarily to the relatively high resilience of BR.

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