Greeks alpha

Alpha decay is denoted by the symbol a (Greek alpha), and the radionuclide essentially just emits an atom of helium with no electrons 2 He see Chapter 2 for isotope symbolism. 

According to quantum mechanics, an electron has two spin states, represented by the arrows T (up) and l(down) or the Greek letters a (alpha) and P (beta) We can think of an electron as being able to spin counterclockwise at a certain rate... 

Unlike his boss, Rutherford was a skilled experimentalist. His apparatuses were usually jury-rigged and crude, but they got the job done. His work with the particles and rays spontaneously emitted by radioactive elements led him to conclude that their emissions came in two forms. With admirable simplicity, Rutherford named them for the first two letters in the Greek alphabet, alpha and beta. After Cambridge, Rutherford accepted physics professorships at universities in Canada and Manchester, England, J.J. Thomsons hometown. He continued to work with radioactive... 

Astatine - the atomic number is 85 and the chemical symbol is At. The name derives from the Greek astatos for unstable since it is an unstable element. It was first thought to have been discovered in nature in 1931 and was named alabamine. When it was determined that there are no stable nuclides of this element in nature, that claim was discarded. It was later shown that astatine had been synthesized by the physicists Dale R. Corson, K. R. Mackenzie and Emilio Segre at the University of California lab in Berkeley, California in 1940 who bombarded bismuth with alpha particles, in the reaction Bi ( He, 2n ) "At. Independently, a claim about finding some x-ray lines of astatine was the basis for claiming discovery of an element helvetium, which was made in Bern, Switzerland. However, the very short half-life precluded any chemical separation and identification. The longest half-life associated with this unstable element is 8.1 hour °At. 

There is no systematic nomenclature developed for molecular sieve materials. The discoverer of a synthehc species based on a characteristic X-ray powder diffraction pattern and chemical composihon typicaUy assigns trivial symbols. The early syn-thehc materials discovered by Milton, Breck and coworkers at Uruon Carbide used the modem Lahn alphabet, for example, zeoHtes A, B, X, Y, L. The use of the Greek alphabet was inihated by Mobil and Union Carbide with the zeoHtes alpha, beta, omega. Many of the synthetic zeoHtes which have the structural topology of mineral zeoHte species were assigned the name of the mineral, for example, syn-thehc mordenite, chabazite, erionite and offretite.The molecular sieve Hterature is replete with acronyms ZSM-5, -11, ZK-4 (Mobil), EU-1, FU-1, NU-1 (ICI), LZ-210, AlPO, SAPO, MeAPO, etc. (Union Carbide, UOP) and ECR-1 (Exxon). The one pubHcaHon on nomenclature by lUPAC in 1979 is Hmited to the then-known zeoHte-type materials [3]. 

The many different monodisperse polymers of amino acids, which are essential components of plants and animals, are called proteins. This word is derived from the Greek porteios meaning of chief importance. The 20 different alpha-amino acids are joined together by peptide linkages (Table 10.1). 

In 1940 D. R. Corson, K. R. Mackenzie, and E. Segre at the University of California bombarded bismuth with alpha particles (26, 27). Preliminary tracer studies indicated that they had obtained element 85, which appeared to possess metallic properties. The pressure of war work prevented a continuation of these studies at the time. After the war, the investigators resumed their work, and in 1947 proposed the name astatine, symbol At, for their element. The name comes from the Greek word for unstable, since this element is the only halogen without stable isotopes (28). The longest lived isotope is At210 with a half-life of 8.3 hours and a very high activity. 

The minns sign in Eq. (4.2) arises dne to the fact that in order for there to be heat flow in the +y direction, the temperatnre gradient in that direction must be negative—that is, lower temperature in the direction of heat flow. If the temperature gradient is expressed in units of K/m, and the heat flux is in J/m - s, then the thermal conductivity has units of J/K m s, or W/m K. A related quantity is the thermal diffusivity, which is often represented by the lowercase Greek letter alpha, a. Thermal diffusivity is defined as k/pCp, where k is the thermal conductivity, p is the density, and Cp is the heat capacity at constant pressure per unit mass. We will see in a moment why the term diffusivity is used to describe this parameter. We will generally confine our descriptions in this chapter to thermal conductivity. 

Interferon alpha A (human leukocyte protein moiety reduced) [CAS alpha is Greek letter] Interferon alpha-2a [SY] alpha-2a interferon [SY]... 

The three most common forms of radiation coming from a radioactive substance are called by the first three letters of the Greek alphabet, OC, (5, J-—alpha, beta, and gamma. In a magnetic field, alpha rays bend one way, beta rays bend the other way, and gamma rays do not bend at all. Note that the alpha rays bend less than do the beta rays. This happens because the alpha particles have more inertia (because they have more mass) than the beta particles. JThe source of all three radiations is a radioactive material placed at the bottom of a hole drilled in a lead block. 

Scientists have known since 1896 that many nuclides are radioactive—that is, they spontaneously emit radiation. Early studies of radioactive nuclei, or radionuclides, by the New Zealand physicist Ernest Rutherford in 1897 showed that there are three common types of radiation with markedly different properties alpha (a), beta (f3), and gamma (y) radiation, named after the first three letters of the Greek alphabet. 

Figure 9.1 A drawing of a constellation Taurus from Johann Bayer s Uranometria (Augsburg 1603). Bayer used Greek letters to designate the brightness of stars. The bright star in the Bull s eye became alpha Tauri, just like the brightest star in the constellation Centaur became our familiar alpha Centauri.

Because helium forms no compounds and is almost absent in the Earth s atmosphere, it was unknown for a long time. The first clue leading to its discovery was an unidentified yellow emission line in the solar chromospheric spectrum observed by French astronomer Pierre Janssen during an eclipse of the Sun in 1868. Lockyer named the unknown element helium for the Greek sun god, helios. Subsequendy it was discovered to be rather abundant in radioactive rocks, where it is trapped after emission from uranium series alpha decays. Ramsay and Soddy showed that the alpha rays were helium atoms whose electrons had been stripped away. In his biography of Lord Rutherford, A. S. Eve wrote ... 

The Greek letter alpha a is used to represent this small residual risk of a false positive. Alpha obviously depends upon what confidence interval is inspected. In the case of the standard 95 per cent Cl, the remaining risk is 100 — 95 = 5 per cent. However, if we were particularly anxious to avoid the risk of a false positive, we might calculate a 98 per cent Cl and only declare a positive finding if that wider interval excluded zero. In that case alpha would be only 2 per cent. 

Superscripts and subscripts may be used with the Greek letters that represent alpha, beta, and gamma particles. Eor example, an alpha particle can be represented by the Greek letter alpha (a) or the symbol " He. In either case, the subscript can be used or omitted. With the Greek letter, the superscript is also... 

You may have noticed that there is a lot more to Figure 9-4. In addition to labeling the alpha carbon atom and pendant R gronp, you can see that there is something called the amide plane and we have used Greek letters, 0 and 0 (pronounced fie and sie to rhyme with pie), to indicate that there are bond rotations around the C°-N and C -C bonds. What about the amide or peptide bond CO-NH To understand what s going on, we need to talk about the nature of die amide bond in a little more depth. 

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