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Beschreibung:
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A sign is an object, quality, event, or entity whose presence or occurrence indicates the probable presence or occurrence of something else. A natural sign bears a causal relation to its object—for instance, thunder is a sign of storm, or medical symptoms a sign of disease. A conventional sign signifies by agreement, as a full stop signifies the end of a sentence; similarly the words and expressions of a language, as well as bodily gestures, can be regarded as signs, expressing particular meanings. The physical objects most commonly referred to as signs (notices, road signs, etc., collectively known as signage) generally inform or instruct using written text, symbols, pictures or a combination of these. Signs are any kind of visual graphics created to display information to a particular audience. This is typically manifested in the form of wayfinding information in places such as streets or on the inside and outside buildings. Signs vary in form and size based on location and intent, from more expansive banners, billboards, and murals, to smaller street signs, street name signs, sandwich boards and lawn signs. Newer signs may also use digital or electronic displays. The main purpose of signs is to communicate, to convey information designed to assist the receiver with decision-making based on the information provided. Alternatively, promotional signage may be designed to persuade receivers of the merits of a given product or service. Signage is distinct from labeling, which conveys information about a particular product or service.
Tin is a soft, malleable, ductile and highly crystalline silvery-white metal. When a bar of tin is bent a crackling sound known as the "tin cry" can be heard from the twinning of the crystals. Tin melts at about 232 °C (450 °F) the lowest in group 14. The melting point is further lowered to 177.3 °C (351.1 °F) for 11 nm particles. Commercial grades of tin (99.8% tin content) resist transformation because of the inhibiting effect of small amounts of bismuth, antimony, lead, and silver present as impurities. Alloying elements such as copper, antimony, bismuth, cadmium, and silver increase the hardness of tin. Tin easily forms hard, brittle intermetallic phases that are typically undesirable. It does not mix into a solution with most metals and elements so tin does not have much solid solubility. Tin mixes well with bismuth, gallium, lead, thallium and zinc forming simple eutectic systems. Tin resists corrosion from water, but can be corroded by acids and alkalis. Tin can be highly polished and is used as a protective coat for other metals, a protective oxide (passivation) layer prevents further oxidation. Tin acts as a catalyst triggering a chemical reaction of a solution containing oxygen and helps to increase the speed of the chemical reaction that results. Therefore, tin signs are very stable in daily life.
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