Elements reactivity

Residence time and reactivity are strongly correlated through equation (7.2.9). This is true for seawater composition since Whitfield and Turner (1979) showed a rather good correlation between oceanic residence times and seawater-crustal rock partition coefficients which are taken as a measure of element reactivity in the ocean. Actually, a better estimate of reactivity is given by oceanic suspensions, so Li (1982) suggested to use pelagic clay-seawater concentration ratios as a proxy to partition coefficients. 

Although the oceanic distributions of rare earth elements somewhat resemble those of nutrients, their behaviors are clearly different in that they are not actively taken up by photoplankton but passively scavenged by particles. Elemental reactivity with suspended particles, which controls, together with sinking of particle aggregates, the mean oceanic residence times of not only REEs but also a number... 

The annular reactor core consists of fuel elements, graphite reflector elements, plenum elements, reactivity control material, and neutron startup sources. Each of these components is described below. 

Gimenez J, Montgiraud C, Pichon J-P, Arsac M, Ruel M, Bouton O, Mailet F. Custom human endogenous retrovirus dedicated microarray identifies self-induced HERV-W family elements reactivated in testicular cancer upon methylation control. Nucleic Acids Res. 2010 38 2229 6. 

Our ideas on main-group element reactivity are not taken out of the blue but are based on parallels with well-studied processes in organic and organoelement chemistry. Second, it no longer necessarily takes a prohibitive amount of resources to test a mechanistic proposal, at least in a preliminary way. Quantum chemical calculations, particularly based on density functional theory (DFT), very often provide an efficient and economical way of evaluating reaction mechanisms. Third, and perhaps most important, it s vastly better to be able to... 

If one limits the calculated array keff to 0.90, for criticality safety, then curves of safe spacing vs the isolated, element k ff approach 0 90 instead of unity at large separations. This is exprated since the interaction approaches zero. The safe spacing Is strongly dependent upon the element reactivity. Most power reactors r uire large numbers of elements for criticality hence, the keff of their Isolated elements is small and safe spacings may be much less ttum 12 in. 

Element Reactivity with N2" Nitride Standard heat of formation/ (kJ-(N-atom)-i, 25°C) Decomposition temperature/ C... 

An element is only activated strongly if it is activated by two or more elements which are synchronous to each other. Activations may be asymmetrical or symmetrical. Symmetrical activation means an element activates its neighboring element after one elementary time and the neighboring element reactivates the first element after another elementary time. 

Core configurations (fuel elements, reflector elements, reactivity control mechanisms) ... 

Element Reactivity with N2 Nitride Standard heat Decomposition of formatiion temperature (kJ/N-atom25°C) (°C) ... 

The reactor pressure vessel internals (core support structures, the core shroud in a BWR and other internals, but excluding fuel elements, reactivity... 

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