Instruct: Given a question, retrieve passages that answer the question.
Query: What material are stents made out of?
In medicine, a stent is a metal or plastic tube inserted into the lumen of an anatomic vessel or duct to keep the passageway open, and stenting is the placement of a stent. There is a wide variety of stents used for different purposes, from expandable coronary, vascular and biliary stents, to simple plastic stents used to allow the flow of urine between kidney and bladder. "Stent" is also used as a verb to describe the placement of such a device, particularly when a disease such as atherosclerosis has pathologically narrowed a structure such as an artery.
The material of choice for producing these screws is stainless steel typically 18-8 (303). At the tip of the screw most commonly a stainless steel ball is either pressed or glued into place to provide a single point contact for the surface being moved. Common usage has shown the glue method of attaching the ball to be troublesome in many applications as some commonly used glues (Super Glue) tend to outgas and degrade over time in this application.
316 stainless steel, also referred to as marine grade stainless steel, is a chromium, nickel, molybdenum alloy of steel that exhibits relatively good strength and corrosion resistance. Along with the titanium alloy Ti6Al4V, 316 stainless is a common choice of material for biomedical implants. Although Ti6Al4V provides greater strength per weight and corrosion resistance, 316 stainless components can be more economical to produce. However, immune system reaction to nickel is a potential complication of 316. 
Implants and equipment that are put under pressure (bone fixation screws, prostheses, body piercing jewelry) are made out of austenitic steel, often 316L and 316LVM compliant to ASTM F138.
316 surgical steel is used in the manufacture and handling of food and pharmaceutical products where it is often required in order to minimize metallic contamination. 
ASTM F138-compliant steel is also used in the manufacture of body piercing jewellery and body modification implants.
Zyex string offers more rebound efficiency, i.e. gut-like dynamic stiffness, than other synthetic strings, particularly when strung at low tensions. This gives it playability that is more similar to natural gut than, arguably, other synthetic materials. It also has low overall stiffness. The ProKennex IQ Element Z string, for instance, has the lowest stiffness of any synthetic string yet tested. The drawback of Zyex is that the outer wrapping materials in Zyex tennis string tend to be much less durable than the Zyex filaments inside the string and do not bond with them. This can lead to the outer wrapping wearing away, leaving the inner Zyex filaments.
Generally, it has been found that scaffolds that closely resemble the natural environments of the tissue being engineered are the most successful. As a result, much research has gone into investigating natural polymers that can be tailored, through processing methodology, toward specific design criteria. Chitosan is currently one of the most widely used polymers as it is very similar to naturally occurring glycosaminoglycan (GAGs) and it is degradable by human enzymes.
Group D
Stainless steels have a long history of application in contact with water due to their excellent corrosion resistance. Applications include a range of conditions from plumbing, potable and waste water treatment to desalination. Types 304 and 316 stainless steels are standard materials of construction in contact with water. However, with increasing chloride contents higher alloyed stainless steels such as Type 2205 and super austenitic and super duplex stainless steels are utilized.
Wire has many uses. It forms the raw material of many important manufacturers, such as the wire netting industry, engineered springs, wire-cloth making and wire rope spinning, in which it occupies a place analogous to a textile fiber. Wire-cloth of all degrees of strength and fineness of mesh is used for sifting and screening machinery, for draining paper pulp, for window screens, and for many other purposes. Vast quantities of aluminium, copper, nickel and steel wire are employed for telephone and data cables, and as conductors in electric power transmission, and heating. It is in no less demand for fencing, and much is consumed in the construction of suspension bridges, and cages, etc. In the manufacture of stringed musical instruments and scientific instruments, wire is again largely used. Carbon and stainless spring steel wire have significant applications in engineered springs for critical automotive or industrial manufactured parts/components. Pin and hairpin making; the needle and fish-hook industries; nail, peg, and rivet making; and carding machinery consume large amounts of wire as feedstock.
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The most known brand of wine screw caps is Stelvin, which is commonly used in the wine industry as generic trademark for any brand of screwcap. The caps have a long outside skirt, intended to resemble the traditional wine capsule ("foil"), and use plastic PVDC (Polyvinylidene chloride) as a neutral liner on the inside wadding.
There are four basic types of knitting needles (also called "knitting pins"). The first and most common type consists of two slender, straight sticks tapered to a point at one end, and with a knob at the other end to prevent stitches from slipping off. Such needles are usually 10-16 inches long but, due to the compressibility of knitted fabrics, may be used to knit pieces significantly wider. The most important property of needles is their diameter, which ranges from below 2 mm to 25 mm (roughly 1 inch). The diameter affects the size of stitches, which affects the gauge of the knitting and the elasticity of the fabric. Thus, a simple way to change gauge is to use different needles, which is the basis of uneven knitting. Although knitting needle diameter is often measured in millimeters, there are several different size systems, particularly those specific to the United States, the United Kingdom and Japan; a conversion table is given in the knitting needle article. Such knitting needles may be made out of any materials, but the most common materials are metals, wood, bamboo, and plastic. Different materials have different frictions and grip the yarn differently; slick needles such as metallic needles are useful for swift knitting, whereas rougher needles such as bamboo are less prone to dropping stitches. The knitting of new stitches occurs only at the tapered ends, and needles with lighted tips have been sold to allow knitters to knit in the dark.
Natural biodegradable polymers are formed in nature during growth cycles of all organisms. When searching for natural fibers to replace synthetic materials in athletic shoes, the major natural biodegradable polymer that offers the most potential are polysaccharides. Starch is a polysaccharide that is useful because it readily degrades into harmless products when placed in contact with soil microorganisms.
While known since 1954, PGA had found little use because of its sensitivity to hydrolysis when compared with other synthetic polymers. However, in 1962 this polymer was used to develop the first synthetic absorbable suture which was marketed under the tradename of Dexon by the Davis & Geck subsidiary of the American Cyanamid Corporation. After its coating with Polycaprolactone and Calcium Stearate is being sold under the brand name of Assucryl.
Most of the time, ‘artificial’ tissue is grown from the patient’s own cells. However, when the damage is so extreme that it is impossible to use the patient's own cells, artificial tissue cells are grown. The difficulty is in finding a scaffold that the cells can grow and organize on. The characteristics of the scaffold must be that it is biocompatible, cells can adhere to the scaffold, mechanically strong and biodegradable. One successful scaffold is a copolymer of lactic acid and glycolic acid.
Electrical wires are usually covered with insulating materials, such as plastic, rubber-like polymers, or varnish. Insulating and jacketing of wires and cables is nowadays done by passing them through an extruder. Formerly, materials used for insulation included treated cloth or paper and various oil-based products. Since the mid-1960s, plastic and polymers exhibiting properties similar to rubber have predominated.
Among the notable discoveries was COROT-7b, discovered in 2009 which became the first exoplanet shown to have a rock or metal-dominated composition.
The term "asbestos ware" refers to vessels containing 90% asbestos and 10% clay. Asbestos ware can resist heat up to 900–1000 °C. The clay made shaping of the vessel possible, but the high amount of asbestos does not classify it as pottery in a formal sense. It is believed that the asbestos ware was used in iron production such as spearheads, arrowheads and artefacts. The vessel is also drilled with many holes. The fact that the reduction of iron ore (FeO) with abundant carbon generates large amounts of carbon monoxide (CO) may suggest that the drilled holes were used to increase the influx of air (oxygen) required for proper glowing process. Iron ore is abundant in lakes e.g. in Finland.
Hosts
Sheet assembly of light aircraft is accomplished predominantly with rivets of alloys 2017-T4, 2117-T4, or 2024-T4. Self-tapping sheet metal screws are available in aluminum alloys, but cadmium-plated steel screws are employed more commonly to obtain higher shear strength and driveability. Alloy 2024-T4 with an anodic coating is standard for aluminum screws, bolts, and nuts made to military specifications. Alloy 6262-T9, however, is superior for nuts, because of its virtual immunity to stress-corrosion cracking.
The saline breast implantfilled with saline solution (biological-concentration salt water 0.90% w/v of NaCl, ca. 300 mOsm/L.)was first manufactured by the Laboratoires Arion company, in France, and was introduced for use as a prosthetic medical device in 1964. The contemporary models of saline breast implant are manufactured with thicker, room-temperature vulcanized (RTV) shells made of a silicone elastomer. The study "In vitro Deflation of Pre-filled Saline Breast Implants" (2006) reported that the rates of deflation (filler leakage) of the pre-filled saline breast implant made it a second-choice prosthesis for corrective breast surgery. Nonetheless, in the 1990s, the saline breast implant was the prosthesis usual for breast augmentation surgery, because of the U.S. FDA's restriction against the importation of silicone-filled breast implants.
Nearly all basketballs have an inflatable inner rubber bladder, generally wrapped in layers of fiber and then covered with a surface made either from leather (traditional), rubber, or a synthetic composite. As in most inflatable balls, there is a small opening that allows the pressure to be increased or decreased.
An example of a naturally dissolving stent is the 'Absorb' stent 'produced by Abbott that has several design components and features: base scaffold: a poly(L-lactide) polymer similar to that in dissolvable stitches is shaped into a tube made up of zigzag hoops linked together by bridges; drug-eluting layer': a mixture of poly-D, L-lactide (PDLLA) and everolimus; 'markers': a pair of radio-opaque platinum markers at the ends that allow the device to be visualized during angiography; 'delivery system': a balloon delivery system.
Just as thrombogenicity is important in determining suitability of other biomaterials, it is equally important with Nitinol as a stent material. Currently, when stents are implanted, the patient receives [[antiplatelet|antiaggregant]] therapy for a year or more in order to prevent the formation of a clot near the stent. By the time the drug therapy has ceased, ideally, a layer of [[endothelial cells]], which line the inside of blood vessels would coat the outside of the stent. The stent is effectively integrated into the surrounding tissue and no longer in direct contact with the blood. There have been many attempts made using surface treatments to create stents that are more biocompatible and less thrombogenic, in an attempt to reduce the need for extensive antiplatelet therapy. Surface layers that are higher in nickel concentration cause less clotting due to albumin’s affinity to nickel. This is opposite of the surface layer characteristics that increase corrosion resistance. In vitro tests use indicators of thrombosis, such as platelet, [[Tyrosine aminotransferase]], and β-TG levels. Surface treatments that have to some extent, lowered thrombogenicity in vitro are:
Ġbejna is shaped in a cheese hurdle made of dried reeds, although now plastic ones are also used. They are traditionally dried in small ventilated rooms, with windows protected by a special mesh mosquito net. It is said that in the past sea water, rather than rennet, was used as a curdling agent.
The cheese is available both from pasteurised and unpasteurised milk.
In 2012, a research group in Japan demonstrated that pyrolytic carbon can respond to laser light or sufficiently powerful natural sunlight by spinning or moving in the direction of the field gradient. The carbon's magnetic susceptibility weakens upon sufficient illumination, leading to an unbalanced magnetization of the material and movement when using a specific geometry.Because blood clots do not easily form on it, it is often advisable to line a blood-contacting prosthesis with this material in order to reduce the risk of thrombosis. For example, it finds use in artificial hearts and artificial heart valves. Blood vessel stents, by contrast, are often lined with a polymer that has heparin as a pendant group, relying on drug action to prevent clotting. This is at least partly because of pyrolytic carbon's brittleness and the large amount of permanent deformation, which a stent undergoes during expansion.