Lead

Rather, plum is derived from the Old English word plume. A really good print at a movie theater will be about 500:1^[1]. The plum, however, does not get its name from this root. A printed page is about 80:1. The Latin plumbum has given birth to a number of terms in the English language:. For reference, the page you're reading now (on a computer monitor) is actually about 50:1. The earliest pencils actually used lead, though 'pencil leads' have been made for the last couple of centuries from graphite, a naturally occurring form (allotrope) of carbon. To illustrate, some manufacturers will measure contrast with the front glass removed, which accounts for some of the wild claims regarding their advertised ratios.

For that reason many universities do not hand out lead-containing samples to women for instructional laboratory analyses. In reality, there are no standardised tests for contrast ratio, meaning each manufacturer can publish virtually any number that they like. Lead is considered to be particularly harmful for women's ability to reproduce. On the surface, this is a great thing. It has been suggested that what was known as "Devon colic" arose from the use of lead-lined presses to extract apple juice in the manufacture of cider. Contrast ratios for plasma displays are often advertised as high as 5000:1. Lead salts used in pottery glazes have on occasion caused poisoning, when acid drinks, such as fruit juices, have leached lead ions out of the glaze. The implication is that a higher contrast ratio means more picture detail.

Paint containing lead has been withdrawn from sale in industralised countries, though many older houses may still contain substantial lead in their old paint: it is generally recommended that old paint should not be stripped by sanding, as this generates inhalable dust. Contrast ratio indicates the difference between the brightest part of a picture and the darkest part of a picture, measured in discrete steps, at any given moment. The concern about lead's role in mental retardation in children has brought about widespread reduction in its use (lead exposure has been linked to schizophrenia). Plasma displays use the same phosphors as CRTs, accounting for the extremely accurate color reproduction. Main article: lead poisoning. In this way, the control system can produce colors across the entire visible spectrum. Although this has been banned in industrialized nations, there was a recent scandal involving lead-laced Mexican candy being eaten by children in California (http://www.ocregister.com/investigations/2004/lead/part1_printable.html). By varying the pulses of current flowing through the different cells, the control system can increase or decrease the intensity of each subpixel color to create hundreds of different combinations of red, green and blue.

At one point in time, some lead compounds, because of their sweetness, were used by candy makers. These colors blend together to create the overall color of the pixel. The historical use of lead acetate (also known as sugar of lead) by the Roman Empire as a sweetener for wine is considered by some to be the cause of the dementia which affected many of the Roman Emperors. One subpixel has a red light phosphor, one subpixel has a green light phosphor and one subpixel has a blue light phosphor. Long term exposure to lead or its salts (especially soluble salts or the strong oxidant PbO₂) can cause nephropathy, and colic-like abdominal pains. Every pixel is made up of three separate subpixel cells, each with different colored phosphors. Lead is a poisonous metal that can damage nervous connections (especially in young children) and cause blood and brain disorders. The phosphors in a plasma display give off colored light when they are excited.

The ranges of isotopic ratios for most natural materials are 14.0 - 30.0 for ²⁰⁶Pb/²⁰⁴Pb, 15.0 - 17.0 for ²⁰⁷Pb/²⁰⁴Pb, and 35.0 - 50.0 for ²⁰⁸Pb/²⁰⁴Pb, although numerous examples outside these ranges are reported in the literature. The current creates a rapid flow of charged particles, which stimulates the gas atoms to release ultraviolet photons. Each is reported relative to ²⁰⁴Pb, the only non-radiogenic stable isotope. When the intersecting electrodes are charged (with a voltage difference between them), an electric current flows through the gas in the cell. The corresponding half-lives of these decay schemes vary markedly: 4.47 × 10⁹, 7.04 × 10⁸ and 1.4 × 10¹⁰ years, respectively. To ionize the gas in a color panel, the plasma display's computer charges the electrodes that intersect at that cell thousands of times in a small fraction of a second, charging each cell in turn. ²⁰⁶Pb, ²⁰⁷Pb and ²⁰⁸Pb are all radiogenic, and are the end products of complex decay chains that begin at ²³⁸U, ²³⁵U and ²³²Th, respectively. A small amount of nitrogen is added to the neon to increase hysteresis.

Lead has four stable, naturally occurring isotopes: ²⁰⁴Pb (1.4%), ²⁰⁶Pb (24.1%), ²⁰⁷Pb (22.1%), and ²⁰⁸Pb (52.4%). This type of panel has inherent memory and does not use phosphors. Main Article: Isotopes of lead. To erase a cell all voltage is removed from a pair of electrodes. The molten lead bullion is then refined by additional smelting with air being passed over the lead to form a slag layer containing any remaining impurities and producing 99.9% pure lead. The ionizing state can be maintained by applying a low-level voltage between all the horizontal and vertical electrodes - even after the ionizing voltage is removed. The lead is then cooled in stages which causes the lighter impurites (dross) to rise to the surface where they can be removed. In a monochrome plasma panel, control circuitry charges the electrodes that cross paths at a cell, causing the plasma to ionize and emit photons between the electrodes.

The concentrate is sintered before being smelted in to produce a 97% lead concentrate. The transparent display electrodes, which are surrounded by an insulating dielectric material and covered by a magnesium oxide protective layer, are mounted above the cell, along the front glass plate. The concentrate, which can range from 50% to 60% lead, is dried and then treated using pyrometallurgy. The address electrodes sit behind the cells, along the rear glass plate. The Froth flotation process separates the lead and other minerals from the waste rock (tailings) to form a concentrate. Long electrodes are also sandwiched between the glass plates, on both sides of the cells. The ore is then treated using extractive metallurgy. The xenon and neon gas in a plasma television is contained in hundreds of thousands of tiny cells positioned between two plates of glass.

In mining, the ore is extracted by drilling or blasting and then crushed and ground. Some 42" sets fell below $1,500 at major retailers like Best Buy and Costco during the 2005 Christmas season, and many of the retailers reported that plasma TVs were among the hottest selling items for that season. But more than half of the lead used currently comes from recycling. But as prices fall and technology advances, they have started to seriously compete against the CRT sets. Other common varieties are cerussite (PbCO₃) and anglesite (PbSO₄). With prices starting around US$2,000 and going all the way up past US$20,000 (as of 2004), these sets did not sell as quickly as older technologies like CRT. The main lead mineral is galena (PbS), which contains 86.6% lead. Also, most cheaper consumer displays appear to have an insufficient color depth - a moving dithering pattern may be easily noticible for a discerning viewer over flat areas or smooth gradients; expensive high-res panels are much better at managing the problem.

Currently lead is usually found in ore with zinc, silver and (most abundantly) copper, and is extracted together with these metals. The biggest drawbacks of plasma technology are the high cost, often lower resolution, and relatively short lifespan. Native lead does occur in nature, but it is rare. Because many plasma displays still have a lower resolution the image quality is often not quite up to the standards of good LCD displays or cathode ray tube sets, but it certainly meets most people's expectations. Recently, lead use is being further curtailed by the RoHS directive. Since each pixel is lit individually, the image is very bright and looks good from almost every angle. lead consumers' compliance with environmental regulations that significantly reduced or eliminated the use of lead in nonbattery products, including gasoline, paints, solders, and water systems. The main advantage of plasma display technology is that a very wide screen can be produced using extremely thin materials.

Much of this shift was a result of the U.S. Competing displays include the Cathode ray tube, OLED, AMLCD, DLP, SED-tv and field emission flat panel displays. By the mid-1980s, a significant shift in lead end-use patterns had taken place. So if you use it at an average of 2-1/2 hours a day, the PDP will last approximately 65 years. The English word "plumbing" also derives from this Latin root. Half life is the point where the picture has degraded to half of its original brightness, which is considered the end of the functional life of the display. Lead's symbol Pb is an abbreviation of its Latin name plumbum. The lifetime of the latest generation of PDPs is estimated at 60,000 hours to half life when displaying video.

Lead pipes that bear the insignia of Roman emperors are still in service and many Roman "pigs" (ingots) of lead figure in Derbyshire lead mining history and in the history of the industry in other English centres. Nominal measuments indicate 150 Watts for a 50" screen. Alchemists thought that lead was the oldest metal and associated it with the planet Saturn. Real life measurements of plasma power consumption find it to be much less than that normally quoted by manufacturers. Lead was mentioned in the Book of Exodus. Plasma displays use as much power per square meter as a CRT or an AMLCD television; in 2004 the cost has come down to US$1900 or less for the popular 42 inch (107 cm) diagonal size, making it very attractive for home-theatre use. In the early bronze age lead was used with antimony and arsenic. The display panel is only 6 cm (2 1/2 inches) thick, while the total thickness, including electronics, is less than 10 cm (4 inches).

Lead has been used by humans for at least 7000 years, because it was (and continues to be) widespread and easy to extract, as well as easy to work with, being both highly malleable and ductile as well as easy to smelt. They have a very high "dark-room" contrast, creating the "perfect black" desirable for watching movies. Lead is the only metal in which there is zero Thomson effect. Plasma displays are bright (1000 lx or higher for the module), have a wide color gamut, and can be produced in fairly large sizes, up to 200 cm (80 inches) diagonally. Lead can be toughened by adding a small amount of antimony or other metals to it. Today the superior brightness and viewing angle, when compared to LCD, of color plasma panels have caused these displays to become one of the most popular form of HDTV. sulfuric acid). In 1997 Pioneer started selling the first Plasma TV to the public.

Because of this property, it is used to contain corrosive liquids (e.g. It was a hybrid based on the plasma display created at the University of Illinois at Urbana-Champaign and NHK STRL, achieving superior brightness. This true metal is highly resistant to corrosion. In 1992, Fujitsu introduced the world's first 21-inch full color display. Lead has a bright luster and is a dense, ductile, very soft, highly malleable, bluish-white metal that has poor electrical conductivity. Nonetheless, plasma's relatively large screen size and thin profile made the displays attractive for high-profile placement such as lobbies and stock exchanges. . There followed a long period of sales decline in the late 1970s as semiconductor memory made CRT displays incredibly cheap.

(But see the article on Bismuth, which has a half life so long it can be considered stable.). The original monochrome (usually orange or green) panels enjoyed a surge of popularity in the early 1970s because the displays were rugged and needed neither memory nor refresh circuitry. Lead has the highest atomic number of all stable elements. Gene Slottow in 1964 for the PLATO Computer System. Lead is used in building construction, lead-acid batteries, bullets and shot, and is part of solder, pewter, and fusible alloys. Bitzer and H. A soft, heavy, toxic and malleable poor metal, lead is bluish white when freshly cut but tarnishes to dull gray when exposed to air. The Plasma display panel was invented at the University of Illinois at Urbana-Champaign by Donald L.

plumbum) and atomic number 82. . Lead is a chemical element in the periodic table that has the symbol Pb (L. This gas mixture is inert and entirely harmless.
. The gas discharge contains no mercury (contrary to the backlights of an AMLCD); a mixture of noble gases (neon and xenon) is used instead. Los Alamos National Laboratory - Lead. A plasma display is an emissive flat panel display where light is created by phosphors excited by a plasma discharge between two flat panels of glass.

A Small Dose of Toxicology:Lead. 41-52, 1968. 1., p. In: Curator, 11, No.

Keisch, B: Discriminating Radioactivity Measurements of Lead: New Tool for Authentication. 413-415, 1968. In: Science, 160, p. Keisch, B: Dating Works of Art Trough their Natural Radioactivity: Improvements and Applications.

1238-1242, 1967. 3767, p. In: Science, 155, No. R.: Dating and Authenticating Works of Art by Measurement of Natural Alpha Emitters.

S., and Edwards, R. L., Levine, A. Keisch, B., Feller, R. Aplomb comes from the French à plomb, meaning plumb vertical, and therefore confident and cool.

Plumbism is the medical term for lead poisoning. sense of plum (derived from plumb) meaning 'completely'. Plumb crazy may derive from the fact that lead poisoning can cause insanity; or, according to the Oxford English Dictionary, from a U.S. Plumbing the depths derives from the use of the lead weight to draw the sounding line down to the bottom of the water body (or to the end of the line if the water's really deep!).

Plumb wall is so-said because a plumb bob is used to find the vertical. Plumb bob or plummet, a small, pointed body of metal the weight of which is used to draw a string vertical under tension, refers to the fact that they were originally made from lead. Plumbing, or system of piping, derives from the fact that pipes were once made of lead. see isotope geochemistry.

See Category:Lead minerals. Lead is used as electrodes in the process of electrolysis. Tetraethyl lead has been used in leaded fuels to reduce engine knocking; however, this is no longer common practice in the Western World due to health concerns. It changes the optical characteristics of the glass and reduces the transmission of radiation.

Lead glass is comprised of 12-28% lead. for lead cooled fast reactors. Molten lead is used as a coolant, eg. Lead is used as shielding from radiation.

[1]. Because of the dangers, European and North American manufacturers use more expensive alternatives such as zinc. Lead is used in some candles to treat the wick to ensure a longer, more even burn. Lead is used as projectiles for firearms and fishing sinkers because of its density, low cost verse alternative products and ease of use due to relatively low melting point.

Lead sticks were used as pencils but has been replaced by graphite for the last 450 years. Lead was used for plumbing in Ancient Rome and water mains and service pipes up until the early 1970's. Lead is used as a coloring element in ceramic glazes, notably in the colors red and yellow. Lead was used as a pigment in Lead paint for white as well as yellow and red colors.

Lead is a major constituent of the Lead-acid battery used extensively in car batteries.