Stability peninsula

Unstable isotopes that lie above the stability peninsula have too many neutrons. Hence they become stable by reducing the relative number of neutrons. This can be accomplished by emitting an electron (Le., COTverting a neutron to a proton through (19.1)). 

On the other hand, the unstable isotopes that lie below the stability peninsula would want to reduce the excess protons, by e.g., either (19.2) or (19.3). Process (19.2) is called electron capture and would not emit a particle, but usually emit y-radiation. Process (19.3) would emit a positron, which has the same character as an electron except for the positive electric charge (instead of negative) this is called P -radiation. 

The effects of a rather distinct deformed shell at = 152 were clearly seen as early as 1954 in the alpha-decay energies of isotopes of californium, einsteinium, and fermium. In fact, a number of authors have suggested that the entire transuranium region is stabilized by shell effects with an influence that increases markedly with atomic number. Thus the effects of shell substmcture lead to an increase in spontaneous fission half-Hves of up to about 15 orders of magnitude for the heavy transuranium elements, the heaviest of which would otherwise have half-Hves of the order of those for a compound nucleus (lO " s or less) and not of milliseconds or longer, as found experimentally. This gives hope for the synthesis and identification of several elements beyond the present heaviest (element 109) and suggest that the peninsula of nuclei with measurable half-Hves may extend up to the island of stabiHty at Z = 114 andA = 184. 

Human activities have resulted in exposure of Antarctic fishes to petroleum-derived PAHs (McDonald et al. 1992). Fish captured near Palmer station on the Antarctic peninsula had induced EROD activities and elevated concentrations of biliary PAH metabolites of phenanthrene and naphthalene when compared to conspecifics from reference sites (McDonald et al. 1995). Artificial reefs consisting of oil and coal flyash stabilized with cement and lime in Florida waters near Vero Beach contained elevated PAH levels ranging from as high as 1.2 mg fluoranthene/kg and 0.25 mg naphthalene/kg. But there is negligible leaching because seawater is not an effective medium for removing PAHs from reef bricks or the ash (Frease and Windsor 1991). 

We now know these predictions were wrong, in part. While we believe there are a group of superheavy nuclei whose half-lives are relatively long compared to lower Z elements, we do not believe they form an island of stability. Rather, we picture them as a continuation of the peninsula of known nuclei (Fig. 15.1 lb). We also believe that their half-lives are short compared to geologic time scales. Therefore, they do not exist in nature. The most stable of the superheavy nuclei, those with Z = 112, N 184, are predicted to decay by a-particle emission with half-lives of 20 days. 

In the following, the climates of countries in Northern and Eastern Africa, the Arabian Peninsula, the Middle East and Southern Asia are presented and analysed, and the most appropriate testing conditions for long-term stability studies are proposed. 

Eegunjobi, AS., 2013. Analysis of laminar flow, thermal stability, and entropy generation in porous channel. Thesis, Cape Peninsula University of Technology, South Africa. 

Other than the standard or the inverted blister test, the island blister test (Allen and Senturia 1989), the peninsula blister test (Dillard and Bao 1991), and the constrained blister test (Chang et al. 1989) have been proposed (Lacombe 2006). These tests are schematically shown in O Fig. 22.3. In the island blister test, a small inner island induces larger driving force for the propagation of the delamination front than that on the periphery (the crack initiation point for the standard blister test), which results in effective demationation at the interface between the film and the substrate. The peninsula blister test is a modification of the island blister test and improves the stability of the delamination. In the constrained blister test, a transparent rigid cover plate prevents the film from bursting while the observation of the delamination front is possible. For theoretical treatment of some of these tests, refer to the documents by Williams (1997). 

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