Equilibrium nuclear synthesis

On his initiative, A. G. Doroshkevich and I. D. Novikov [56] constructed a global spectrum of the electromagnetic radiation in the Universe and showed that relic radiation in thermodynamic equilibrium can be found in the centimeter region. The discovery of relic radiation answered the question of what model to choose for the Universe. Ya.B. became an ardent proponent of the theory of a hot Universe (see the 1966 review [26 ]). He was one of the first in the world to understand what a powerful tool relic radiation represented for discovery of the Universe s past. His reviews of 1962-1966, which became the basis for excellent books written later with I. D. Novikov [57-59], contain practically all the ideas which have now become the methods for studying the large-scale structure of the Universe. These include the question of dipole and quadrupole anisotropy, and of angular fluctuations of relic radiation, the problem of nuclear synthesis reactions in the hot Universe, and the quark problem, first raised by Ya.B. together with L. B. Okun and S. B. Pikelner (1965) [11 ]. 

It has been demonstrated [62] that nuclear synthesis can be rationalized in terms of continued a-particle (4He) addition, starting from the elementary units He (n = 2,3,4, 5), to yield the four modular series of nuclides shown in Figure 4.2. By assumption this process happens under cosmic conditions where all stable nuclides consist of protons and neutrons in the ratio Z/N = 1. The even mass number series, A = 4n and A = 4n + 2, result from the equilibrium chain reactions ... 

Alpher s preference is clearly conditioned by cosmology rather than science, but in the event it led to the total elimination of the equilibrium model from subsequent enquiry. A complicating factor in the argument is the continuously changing evidence provided by astronomical observation, in both theories, the success is measured in terms of predicted nuclear abundances and invariably these predictions depend on the nature and characteristics of known types of star, assumed as the seat of nucleogenesis. As more powerful telescopes identify new types of heavenly body, new possibilities of nuclear synthesis open up and the model has to be reworked. This process continues for the a — /d — 7 model only. The equilibrium model was abandoned before the discovery of quasars and black holes, that obviously provide more attractive environments for nuclear synthesis. The only mechanism for the dispersal of freshly synthesized material is still assumed to be supernovae and this assumption could also stand reassessment. 

It is instructive to examine the model that was used to simulate nuclear synthesis in a state of statistical equilibrium which was subsequently frozen down. The probability of the system being in a given quantum state with N neutrons and Z protons with chemical potentials /i and A respectively is given by the grand canonical ensemble... 

Comparison with modern abundance data shows that an exponential function is not such a disastrously wrong predictor of abundances as to discount all equilibrium models, particularly if nuclear synthesis is driven by neither a great event nor continuous creation. A clear resemblance between abundances in the 4n, 4n - - 2 and 4n 1 series points to an equilibrium model. 

Now we are ready to test the hypothesis of nuclear synthesis by a-addition in an equilibrium process, which requires that the relative abundance of each nuclide within a common group must be directly related to its relative stability. The amazing reality is that, despite the imcertainty associated with the measurement of solar abundances, the correlation between nuclear stability and estimated abundance is totally convincing. The binding energy per nucleon and the reported abundance for the nuchdes in the A = 4m + 2 series, with Ne = 6, i.e. for the relevant isotopes of Ca to Kr, are shown in Figure 5.14 as a typical example. The correlation is unmistakable. There is no evidence of any discontinuity at Fe, as required by non-equilibrium models of nucleogenesis. 

The final conclusion is clear Uniform correlation between nuclear stability and abundance cannot result from nucleogenesis in a large number of unrelated processes under a variety of reaction conditions, as required by the big-bang mechanism. The suggested alternative of nuclear synthesis by an equilibrium process of systematic a-addition points at a completely different cosmological model and to the direction which this enquiry must follow, while remaining consistent with physical theory. 

In neutron-rich quasiequilibria ssZn is a very abundant jinal product with special meanings. It is actually synthesized as ssNi in settings with about 15% more neutrons than protons. Its pairing uuth 4 Ca reveals a consequential difference between nuclear thermal (statistical) equilibrium and quasiequilibrium (seeGlossary). Inthejbrmer, thejrnal ssZn will be too abundant jbr 4 Ca synthesis to be possible, whereas in the latter, 4 Ca becomes the more overabundant ofthe two. 

Ca) (iii) the nuclear statistical equilibrium peak at the position of Fe and (iv) the abundance peaks in the region past iron at the neutron closed shell positions (zirconium, barium, and lead), confirming the occurrence of processes of neutron-capture synthesis. The solar system abundance patterns associated specifically with the slow (s-process) and fast (r-process) processes of neutron capture synthesis are shown in Figure 2. 

Cation control of equilibrium and rate processes in initiation of protein synthesis. M. Grunberg-Manago, H. B. Hoa, P. Douzou and A. Wishnia, Adv. Inorg. Biochem., 1981,3,193-232 (78). Metal ion effects on nuclear protein phosphorylation. M. O. J. Olson, Adv. Inorg. Biochem., 1981, 3,167-191 (123). 

At a temperature of 100 million degrees and density of 10,000 g cm in the center of a star, there is an equilibrium involving three alpha particles and an excited state of the carbon-12 nucleus, with energy 7.653 MeV greater than the normal state of the nucleus. The excited -C nucleus can change to the normal state by emission of a photon. Various other known nuclear reactions can then lead to the synthesis of all of the heavier nucleides. 

The kinetic and equilibrium parameters of L-malate, succinate, citrate, and a-oxoglutarate uptake have been determined in mitochondria isolated from respiratory-competent cells grown under conditions of aerobic derepression, aerobic and anaerobic catabolite repression, and inhibition of mitochondrial protein synthesis, and also in mitochondria prepared from a respiratory-deficient cytoplasmic petite strain. The activity and kinetic characteristics of the systems were similar in all cases. It may be concluded that the protein components of these transport systems are coded entirely by nuclear DNA and are synthesized on the cytoplasmic ribosomes. 

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