Nuclear reactivity

Equations (63) and (64) resolve issue four. Nuclear reactivity indices have been defined and clearly display the drivers of the nuclear response to transfers of electrons into and out of the system. The rescaled frontier-orbital density /5F(r) drives that response through the screened force, Eq. (65), when Jf is changed directly, Eq. (63), and the local DOS g(r, fi) drives it when fi is changed, Eq. (64). 

Finally, just as we were able to define in Sect. 5 the nuclear softness, a local nuclear reactivity index in analogy with the electronic local softness, we can now introduce nonlocal nuclear reactivity indices in analogy to the electronic softness kernels [3], We define the nuclear softness kernels as follows... 

It was pointed out in [2,3] that nuclear-configuration changes define chemical reactions so that nuclear reactivities should be defined and set on equal footing with the corresponding electronic reactivities. Thus nuclear Fukui functions , Eq. (59), and nuclear softnesses a Eq. (60), were defined in [2], and explicit Kohn-Sham expressions were found for them, Eqs. (61H64), as reviewed in Sect. 5. These are electron-transfer reactivities and are valid only for extended systems, leaving open the question of nuclear electron-transfer reactivities for localized systems and nuclear isoelectronic reactivities for all systems. 

One approach has been to define nuclear softness functions, cja, and nuclear reactivity indices,... 

A third approach has been to identify a nuclear reactivity index, h f), which defines a local hardness ... 

An antibody to the car boxy-terminal (C-terminal) region of the WT gene (WTl) is useful in recognition of desmoplastic small round cell tumor. DSRCT shows strong nuclear staining with a C-terminal WTl antibody WT and RMS can also show nuclear reactivity for WTl.37,47,48 have observed occasional examples of... 

FIGURE 17.13 Myo-Dl displays nuclear reactivity in rhabdomyosarcoma but may be difficult to interpret because of background cytoplasmic staining (immunoperoxidase, x400). 

FIGURE 17.18 FLI-1 protein expression with nuclear reactivity is found in Ewing s sarcoma/primitive neuroectodermal tumor but can also be observed in other small round blue cell tumors, particularly lymphoblastic lymphoma (immunoperoxidase, x400). 

FIGURE 17.25 WT1 using an antibody to the C-terminus shows diffuse nuclear reactivity in desmoplastic small round cell tumor (immunoperoxidase, x400). 

FIGURE 17.39 Nuclear reactivity for p53 is present in anaplastic Wilms tumor and is associated with p53 mutation (immunoperoxidase, x400). 

Electron-donating groups have a dual effect rate enhancement owing to electronic factors, as expected for electrophilic aromatic substitution, and a rate deerease as a result of steric and transport restrictions. Even the size of the methyl group in toluene is sufficient to compensate for the increased electron density on the aromatie nucleus, as shown by competition kinetics (benzene/toluene 1 1.3 for TS-I/H2O2, 1 10 for trifluoroperacetic acid) [2,27]. The nuclear reactivity trend of alkylbenzenes was in the sequence toluene > /7-xylene > ethylbenzene > /7-methylethylbenzene, in accordance with increasing molecular size... 

The length of time that fuel can be used in a reactor before it must be discharged depends on the characteristics of the reactor, the initial composition of the fuel, the neutron flux to which it is exposed, and the way in which fuel is managed in the reactor, as described in more detail in Chap. 3. Factors that eventually require fuel to be discharged include deterioration of cladding as a result of fuel swelling, thermal stresses or corrosion, and loss of nuclear reactivity... 

Because the thorium atom density is higher in thorium metal than in any thorium compound, metal is the preferred form of thorium where the hipest nuclear reactivity or hipest density is wanted. One likely nuclear application is in a sodium-cooled fast reactor where thorium would capture a neutron and be converted to... 

Relationship with Nuclear Reactivity Descriptors in Isomorphic Ensemble.69... 

RELATIONSHIP WITH NUCLEAR REACTIVITY DESCRIPTORS IN ISOMORPHIC ENSEMBLE... 

In this section, we will show that isomorphic local hardness is linked to nuclear reactivity descriptors in the isomorphic ensemble. This relationship is given by ... 

When two or more identical subcrits are considered as an Meracting array, their nuclear reactivity may be expressed as an interaction potential Im,... 

A. E. SMITH, Nuclear Reactivity Evaluations of 216-Z-9 Enclosed Trench, ARH-2915, AtlanUc Richfield Hanford Company (Dec. 1973). 

Section 3 discusses the control of nuclear reactivity and the safety circuitry provided for shutting the reactor down> Section 6 the heat dissipation plant and Section 7 the system provided to confine fission products within the reactor building. This part of the document will therefore not dwell on these systems but rather with the events following various accidents and possible mechanisms leading to various accidents. 

Nuclear reactivity indices in the spin-resolved framework Applications... 

A final set of reactivity indices constitute the so-called nuclear reactivity indices. As can be seen from eqn (26), the Fukui function measures the electron density response due to the change of the number of electrons of the system. However, despite the fact that the electron density determines all ground state properties of an atomic or a molecular system, the response of the nuelei due to this perturbation remains unknown a reponse kernel is needed to translate electron density changes in external potential changes. Cohen et at. circumvented this problem by introducing a nuclear Fukui function, which they defined as the Hellmann-Feynman force F acting on the nuclei due to a perturbation in the number of electrons at a constant external potential ... 

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