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Class I insulation requires that the metal body and other exposed metal parts of the device be connected to earth via a grounding wire that is earthed at the main service panel—but only needs basic insulation on the conductors.
Piezoelectric balance presented by Pierre Curie to Lord Kelvin, Hunterian Museum, Glasgow. Piezoelectricity (/ ˌ p iː z oʊ-, ˌ p iː t s oʊ-, p aɪ ˌ iː z oʊ-/, US: / p i ˌ eɪ z oʊ-, p i ˌ eɪ t s oʊ-/) [1] is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in ...
1960 onwards: The hip replacement operation (in which a stainless steel stem and 22mm head fit into a polymer socket and both parts are fixed into position by PMMA cement) pioneered by John Charnley (1911–1982). 1960s: First use of sodium cromoglycate for asthma prophylaxis associated with Roger Altounyan (1922–1987). [96]
Since the early 2010s, CRTs have been superseded by flat-panel display technologies such as LCD, plasma display, and OLED displays which are cheaper to manufacture and run, as well as significantly lighter and thinner. Flat-panel displays can also be made in very large sizes whereas 40–45 inches (100–110 cm) was about the largest size of a CRT.
The Space Shuttle Solid Rocket Booster (SRB) was the first solid-propellant rocket to be used for primary propulsion on a vehicle used for human spaceflight. [1] A pair of them provided 85% of the Space Shuttle's thrust at liftoff and for the first two minutes of ascent.
The limiting value of the albedo for high-Z materials is reached when the thickness is 5–10 g/cm 2, or 0.5–1.0 free paths. Thus, a hohlraum made of uranium much thicker than a free path of uranium would be needlessly heavy and costly. At the same time, the angular anisotropy increases as the atomic number of the scatterer material is reduced.
For example, some sands only need to withstand 650 °C (1,202 °F) if casting aluminum alloys, whereas steel needs a sand that will withstand 1,500 °C (2,730 °F). Sand with too low refractoriness will melt and fuse to the casting. [13] Chemical inertness — The sand must not react with the metal being cast.