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Hydrogen (1 H) has three naturally occurring isotopes, sometimes denoted 1 H, 2 H, and 3 H. 1 H and 2 H are stable, while 3 H has a half-life of 12.32(2) years. [3] [nb 1] Heavier isotopes also exist, all of which are synthetic and have a half-life of less than one zeptosecond (10 −21 s).
Naturally occurring lithium (3 Li) is composed of two stable isotopes, lithium-6 (6 Li) and lithium-7 (7 Li), with the latter being far more abundant on Earth. Both of the natural isotopes have an unexpectedly low nuclear binding energy per nucleon (5 332.3312(3) keV for 6 Li and 5 606.4401(6) keV for 7 Li) when compared with the adjacent lighter and heavier elements, helium (7 073.9156(4) keV ...
The CD4 + /CD8 + ratio in the peripheral blood of healthy adults and mice is about 2:1, and an altered ratio can indicate diseases relating to immunodeficiency or autoimmunity. [ 2] An inverted CD4 + /CD8 + ratio (namely, less than 1/1) indicates an impaired immune system. [ 3][ 4][ 5] Conversely, an increased CD4 + /CD8 + ratio corresponds to ...
The standard designation for a UTS thread is a number indicating the nominal (major) diameter of the thread, followed by the pitch measured in threads per inch.For diameters smaller than 1 / 4 inch, the diameter is indicated by an integer number defined in the standard; for all other diameters, the inch figure is given.
In mathematics, a percentage (from Latin per centum 'by a hundred') is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign (%), [ 1] although the abbreviations pct., pct, and sometimes pc are also used. [ 2] A percentage is a dimensionless number (pure number), primarily used for expressing proportions ...
A simple fraction (also known as a common fraction or vulgar fraction, where vulgar is Latin for "common") is a rational number written as a / b or , where a and b are both integers. [ 9] As with other fractions, the denominator ( b) cannot be zero. Examples include 1 2 , − 8 5 , −8 5 , and 8 −5 .
The 4-8-4 type evolved in the United States soon after the Lima Locomotive Works introduced the concept of "Lima Super Power" in 1925, making heavy 2-8-2 and 2-8-4 locomotives. The prototype was built by American Locomotive Company (ALCO) for the Northern Pacific Railway (NP) in 1926, with a very large firebox with a 100-square-foot (9.3 m 2 ...
The Saab 9-3 (pronounced nine-three) is a compact executive car initially developed and manufactured by the Swedish automaker Saab . The first generation 9-3 (1998–2003) is based on the GM2900 platform, changing to the GM Epsilon platform with the introduction of the second-generation car (2003–2012).