Carbon inhibition

Radiolytic oxidation is important to the design and operation of reactors because it adversely affects key graphite properties and, by removing moderator material, may bring about the need for increased fuel enrichment. As mentioned earlier, an inhibitor (methane) is added to the coolant to reduce radiolytic oxidation to acceptable levels. However, access of the inhibitor to the inner portions of the moderator brick must be assured. Two approaches have been adopted in the AGRs to provide this access. Vertical methane access holes are provided in the fuel bricks and in the later stations, Heysham II and Tomess, a pressure drop from outside to inside the brick was established to cause an enhanced flow through the brick. The amount of inhibitor added must be restricted, however, because the carbon inhibition reaction product deposits on the fuel pin and restricts heat transfer to the coolant, thus reducing reactor efficiency. 

Murugesan S, Mousa S, O Connor LJ, Lincoln DW, Linhardt RJ (2007) Carbon inhibits vascular endothelial growth factor- and fibroblast growth factor-promoted angiogenesis. Febs Letters 581 1157-1160. 

Evaluation of the Copolymers The polymer solutions were evaluated for their deposit control and dispersant activities. The tests included calcium phosphate inhibition, calcium carbonate inhibition, iron oxide dispersion, and clay dispersion. The procedures for these tests have been previously reported (12). A commercially available polyacrylic acid was also tested for comparison. The results are shown in Tables II to V. 

Calcium Carbonate Inhibition The test procedure included mixing calcium chloride solution (with and without treatment) and calcium carbonate solution. 

Halogenation of sp3 or sp2 carbon inhibits abstraction and addition reactions by factors of 10 or more, whereas substitution by alkoxy groups or conjugation of two or more double bonds increases rates by factors of 10-100 (Hendry et al., 1974). Thus furans are both conjugated and oxygen substituted, leading to rapid oxidation. 

On the other hand, markedly different behavior was observed during reaction for H2S adsorption on Ni 140) and for S02 adsorption on Pt (81, 131). Erekson and Bartholomew (140) observed that during methanation of CO on polycrystalline Ni, the number of sulfur atoms required to deactivate one nickel atom decreased from 1.0 to 0.23 as the mol % of CO (H2 diluent h2s — 0-2 ppm) was increased from 2 to 20%. During those experiments H2S and COS appeared in the exit stream when the CO concentration was 5% or above. At 20 mol % CO only 1/4 of the reactant H2S (and apparently none of the COS) adsorbed on the catalyst, suggesting that adsorbed CO or carbon inhibits H2S adsorption. 

Logan s own psychiatrist, Fieve, coauthored an article (Polatin et al., 1971) describing three individuals (rare cases, in the authors opinion) who rejected maintenance lithium, two of whom did so specifically on the grounds that it interfered with their creativity as writers of bestsellers These patients report that lithium carbonate inhibits creativity so that the individual is unable to express himself, drive is diminished, and there is no incentive. ... 

Selective reduction of the y,8-double bond of the dienal shown in Scheme 25 was achieved by hydrogenation over palladium on carbon inhibited by quinoline and sulfur. Without inhibition, hydrogenation to the saturated aldehyde was observed. ... 

Selectivity is obtained with prereduction of the catalyst or by using modifiers. Selective reduction of the -y,5-double bond in 20 proceeds quantitatively over Pd-on-carbon inhibited by quinoline and sulfur in methanol containing triethylamine ... 

Li et reported a novel method of obtaining nickel oxide particles with controlled crystalline size and fibrous shape, highly dispersed on in situ produced carbon, inhibiting further growth of Ni particles. On the other hand, Ni/CFC (filamentous carbon) catalysts were shown to have sufficient efficiency in low-temperature methane decomposition. Thus, the use of CFG, whose textural properties can be modified by their activation with Hg or COg, opens up the possibility of its application as a support in heterogeneous catalysis. Methane decomposition over Ni-loaded activated carbon (AC) was also investigated. XRD results showed absence of NiO with only Ni metal crystallites formed in the catalyst even if calcined in Ar, which eliminates the inevitable reduction step with other supports. However, the formation of NisC during the process leads to deactivation of the catalysts. Filamentous carbon formation is... 

Close proximity of the transient bonds to the respective asymmetric carbons Inhibition of free rotation of the transient bonds Minimal non-contributing associative forms that do not bring the respective asymmetric centers to proximity... 

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