Nuclear skin

A4/ f), four times the helion radius. The thickness of the nuclear skin corresponds to the nubbled surface of the outer hemispheres of an outer layer of spherons. In a large nucleus the region within the outer layer would be lined with another layer of spherons, in contact with the outer layer, and within this layer there might be a central spheron or layer of spherons. 

Another question we might pose to ourselves is whether the neutron and proton distributions in nuclei are the same Modern models for the nuclear potential predict the nuclear skin region to be neutron-rich. The neutron potential is predicted to extend out to larger radii than the proton potential. Extreme examples of this behavior are the halo nuclei. A halo nucleus is a very n-rich (or p-rich) nucleus (generally with low A) where the outermost nucleons are very weakly bound. The density distribution of these weakly bound outermost nucleons extends beyond the radius expected from the R °c A1 /3 rule. Examples of these nuclei are nBe, nLi, and 19C. The most well-studied case of halo nuclei is 1 Li. Here the two outermost nucleons are so weakly bound (a few hundred keV each) as to make the size of 11 Li equal to the size of a 208Pb nucleus (see Fig. 2.12). 

When (r — c)/a > 1, p(r) 0 and V)y(r) -> —Z/r, and the simple Coulomb potential may be used for r > lOR. Care is required in selecting an integration grid which is sufficiently dense over the nuclear skin region where the charge density is changing rapidly. An analytic Fourier-Bessel expansion which may be used in finite-difference calculations is presented in [75]. However, the complexity of (109) makes the calculation of the potential matrix required in (99)... 

Fig. 16. Nuclear skin thickness in stable barium isotopes (Ref. 60a). (Courtesy E.B. Shera.)...

The case of thin-skin regime appears in various industrial sectors such as aerospace (with aluminium parts) and also nuclear in tubes (with ferromagnetic parts or mild steel components). The detection of deeper defects depends of course on the choice of the frequency and the dimension of the probe. Modelling can evaluate different solutions for a type of testing in order to help to choose the best NDT system. 

Vitamin D is not strictly a vitamin since it can be synthesized in the skin, and under most conditions that is its major source. Only when sunlight is inadequate is a dietary source required. The main function of vitamin D is in the regulation of calcium absorption and homeostasis most of its actions are mediated by way of nuclear receptors that regulate gene expression. Deficiency—leading to rickets in children and osteomalacia in adults—continues to be a problem in northern latitudes, where sunlight exposure is poor. 

Immunological abnormalities were reported in 23 adults in Woburn, Massachusetts, who were exposed to contaminated well water and who were family members of children with leukemia (Byers et al. 1988). These immunological abnormalities, tested for 5 years after well closure, included persistent lymphocytosis, increased numbers of T-lymphocytes, and depressed helper suppressor T-cell ratio. Auto-antibodies, particularly anti-nuclear antibodies, were detected in 11 of 23 adults tested. This study is limited by the possible bias in identifying risk factors for immunological abnormalities in a small, nonpopulation-based group identified by leukemia types. Other limitations of this study are described in Section 2.2.2.8. A study of 356 residents of Tucson, Arizona, who were exposed to trichloroethylene (6-500 ppb) and other chemicals in well water drawn from the Santa Cmz aquifer found increased frequencies of 10 systemic lupus erythematosus symptoms, 5 (arthritis, Raynaud s phenomenon, malar rash, skin lesions related to sun exposure, seizure or convulsions) of which were statistically significant (Kilbum and Warshaw 1992). 

Matousek J. Means for decontamination of supertoxic lethal chemicals on human skin. Symposium on Nuclear, Biological and Chemical Threats in the 21st Century, NBC-2000, Helsinki-Espoo 2000. Symposium Proceedings, Research Report No 75, University of Jyvaskyla 2000, pp. 216-221. 

Mass spectrometry (MS), nuclear magnetic resonance (NMR) spectrography, electron skin resonance (ESR) spectrography, ultraviolet, infrared and visible... 

Green function method, that can be considered as a generalization of the BHF approach. The results are compared with those from various many-body approaches, such as variational and relativistic mean field approaches. In view of the large spread in the theoretical predictions we also examine possible constraints on the nuclear SE that may be obtained from information from finite nuclei (such the neutron skin). 

Two forms of gold provide medical treatments. The radioactive isotope Au-198, with a short half-life of 2.7 days, is used to treat cancer and is produced by subjecting pure gold to neutrons within a nuclear reactor. A gold salt, a solution called sodium thiosulfate (AuNa O Cl ), is injected as an internal treatment for rheumatoid arthritis. However, since gold and some of its compounds are toxic when ingested, this treatment may cause complications such as skin rashes and kidney failure. It is a less popular treatment, particularly with the development of newer and more effective medications. 

Phosphorus-32, the most important radioisotope of phosphorus, has a half-life of 14 days. It provides beta radiation (high-speed electrons) and is made by inserting phosphorus into nuclear reactor piles. P-32 is used as a tag to trace biochemical reactions in patients. It is also used to treat leukemia and skin and thyroid diseases. 

Beryllium is an important metal alloy used in the nuclear power industry. Its presence in coal and oil results in more than 1250 tons being released into the environment annually from fuel combustion at power plants. Exposure is primarily from inhalation, but skin contact can result in dermatitis. Cigarette smokers also inhale a little beryllium. Initially, beryllium distributes to the liver, but ultimately is absorbed by bone. 

Retinoids are a family of naturally occurring and synthetic analogues of vitamin A. The skin of subjects deficient in vitamin A becomes hyperplastic and keratotic (phrynoderma, or toad skin). While natural vitamin A is occasionally employed therapeutically, synthetic retinoids are more effective and represent a major advance in dermatological pharmacotherapy. Retinoids have myriad effects on cellular differentiation and proliferation it is likely that nuclear retinoic acid receptors mediate these effects by activating gene expression in a manner analogous to receptors for steroid hormones and thyroid hormones. Despite a common mechanism of action, however, retinoids vary widely in their physiological effects. 

Gelatin is derived from the fibrous protein collagen, which is the principal constituent of animal skin, bone, and connective tissue. Fish skin waste could be used as a potential source to isolate collagen and gelatin. Zhu et al. (2010) evaluated the effect of collagen peptides on markers of metabolic nuclear receptors. 

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