Surfaces textures

With biomolecule modified surfaces, there may also be important questions regarding the possible deleterious effects of sterilization procedures required before implantation. 

Because the variables affecting cardiovascular device responses are sufficiently numerous and complex, those properties of blood-contacting surfaces which would be desirable to minimize adverse reactions cannot, in most instances, be predicted with confidence. The choice of material is usually constrained by mechanical property considerations and by variable requirements for material durability and chemical stability. Cardiovascular device engineering must therefore be guided by previous experience in successful clinical applications. 

Colman, R.W., Hirsch, J., Marder, V.J. and Salzman, E.W. (eds)(1994) Hemostasis and Thrombosis Basic Principles and Clinical Practice, 3rd edn, J.B. Lippincott, Philadelphia. 

This book is highly recommended. This state-of-the-art text covers in detail essentially all important hematological aspects of cardiovascular device blood compatibility. In particular, Chapter 76, Interaction of blood with artificial surfaces, which considers many theoretical, experimental, and animal studies, and Chapter 77, Artificial devices in clinical practice, which describes clinical device thromboembolic complications, are of great practical value. 

Marker, L.A., Ratner, B.D. and Didisheim, P. (eds)(1993) Cardiovascular Biomaterials and Biocompatibility, Cardiovascular Pathology, 2(3) (suppl.), 1S-224S. 

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Polymers. Ion implantation of polymers has resulted in substantial increases of electrical conductivity (140), surface hardness (141), and surface texturing (142). A four to five order of magnitude increase in the conductivity of polymers after implantation with 2 MeV Ar ions at dose levels ranging from 10 -10 ions/cm has been observed (140). The hardness of polycarbonate was increased to that of steel (141) when using 1 MeV Ar at dose levels between 10 -10 ions/cm. Conductivity, oxidation, and chemical resistance were also improved. Improvements in the adhesion of metallizations to Kapton and Teflon after implantation with argon has been noted (142). 

Plastic Sheet. Poly(methyl methacrylate) plastic sheet is manufactured in a wide variety of types, including cleat and colored transparent, cleat and colored translucent, and colored semiopaque. Various surface textures ate also produced. Additionally, grades with improved weatherabiUty (added uv absorbers), mat resistance, crazing resistance, impact resistance, and flame resistance ate available. Selected physical properties of poly(methyl methacrylate) sheet ate Hsted in Table 12 (102). 

The fabric may also be given one or more of a number of other finishing treatments, either ia tandem with web formation and bonding or off-line as a separate operation, as a means of enhancing fabric performance or aesthetic properties. Performance properties iaclude functional characteristics such as moisture transport, absorbency, or repeUency flame retardancy electrical conductivity or static propensity abrasion resistance and frictional behavior. Aesthetic properties iaclude appearance, surface texture, and smell. 

Under mechanical and environmental stresses, composites are dimensionally stable. They maintain their shape and functionaHty, a critical requirement in such appHcations as dish antennas, constmction girders, and in appHance and business machines. Color and surface texture can often be molded into an FRP product for long lasting, low maintenance permanent surface appearance. Boats are a good example. The surface color is molded in and requires minimum maintenance, an advantage in saltwater environments. 

The dielectric breakdown strength in vitreous siUca depends on its impurity content, its surface texture, and the concentration of stmctural defects, such as cord and bubbles. Good quaUty glasses have room temperature breakdown strength in the range of 200—400 kV/cm. 

Transmission electron micrographs show hectorite and nontronite as elongated, lath-shaped units, whereas the other smectite clays appear more nearly equidimensional. A broken surface of smectite clays typically shows a "com flakes" or "oak leaf surface texture (54). High temperature minerals formed upon heating smectites vary considerably with the compositions of the clays. Spinels commonly appear at 800—1000°C, and dissolve at higher temperatures. Quartz, especially cristobalite, appears and mullite forms if the content of aluminum is adequate (38). 

Sepn. Purif., 3, 19 (1989)] takes holdup into account and applies to random as well as structured packings. It is somewhat cumbersome to use and requires three constants for each packing type and size. Such constants have been evaluated, however, For a number of commonly used packings. A more recent pressure drop and holdup model, suitable for extension to the flood point, has been pubhshed by Rocha et al. [Jnd. Eng. Chem. Research, 35, 1660 (1996)]. This model takes into account variations in surface texturing of the different brands of packing. 

BS 1134 1990 Part 2 - Assessment of. Surface Texture - Guidance and General Information. London BSI. 

Ultrafiltration utilizes membrane filters with small pore sizes ranging from O.OlS t to in order to collect small particles, to separate small particle sizes, or to obtain particle-free solutions for a variety of applications. Membrane filters are characterized by a smallness and uniformity of pore size difficult to achieve with cellulosic filters. They are further characterized by thinness, strength, flexibility, low absorption and adsorption, and a flat surface texture. These properties are useful for a variety of analytical procedures. In the analytical laboratory, ultrafiltration is especially useful for gravimetric analysis, optical microscopy, and X-ray fluorescence studies. 

ANSI-B 1.20.1 Pipe Threads, General Purpose ANSI-B46.1 Surface Texture ANSI-BI6.5 (1988) Pipe Flanges and Flanged Fittings ANSI-B3 1.3 (1990) Chemical Plant and Petroleum Piping... 

Fig. 2.14 Surface textures of rust on (a) mild steel and (b) Cor-Ten steel exposed in an industrial atmosphere for 2-5 years [(a) x 12M and (b) x 1 3201...

Available shapes Available sizes Available surface texture Manufacturing tolerances... 

Available shapes Availeble sizes Manufacturing tolerances Available surface texture... 

Control size, shape, and surface texture of molded article... 

Zhou, L., Kato, K., Vurens, G., and Talke, F. E., The Effect of Slider Surface Texture on Flyability and Lubricant Migration under Near Contact Conditions, Tribal. Int., Vol. 36, No. 4-6,... 

Philipossian, A. and Olsen, S., Effect of Pad Surface Texture and Slurry Abrasive Concentration on Tribological and Kinetic Attributes of ILD CMP," Materials Research Society Symposium Proceedings, Vol. 161,2003, F2.8. 

Fleeter, F., Oingerdlssen, N., and Hartmann, C., "The Eyaluation of Surface Texture Measurements on Organic Coatings", 13th International Conference in Organic Coatings Science and Technology. 

The metal surface is polycrystalline and has a rather complex profile. Because of different crystallite orientations at the surface, different crystaf faces are exposed, such as smooth fow-index faces and stepped high-index faces. Surface texture where a particufar kind of face is predominant can devefop in individual cases. Microcracks and various lattice defects (dislocations, etc.) will also emerge at the surface. 

Aluminium powder can (depending on the surface texture of the metal) react with water, forming hydrogen, which can provoke explosions due to the overpressures created if the interaction occurs in a closed container. The same thing happens, whatever the surface texture, if the reaction occurs with an aqueous sodium hydroxide solution. 

It is very difficult to handle since it combusts spontaneously in air. The fire is difficult to put out and requires special extinguishing agents. With liquid oxygen the reaction leads to a violent detonation. The surface texture of titanium seems to be an important element in the violence of the effects obtained. 

Finely powdered cobalt can detonate spontaneously in air. Its behaviour depends on its surface texture. Raney cobalt is much more dangerous than Raney nickel, which is more commonly used (see nickel). 

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