The degradation of azo dyes has attracted many research efforts not only due to the resulting environmental problems but also because the azo compounds with various substituents may show different degradation mechanism. It has been computationally found here, for the first time, that the HO• initiated cleavages of C-N and N-N bonds of alizarin yellow R with carboxyl group are kinetically competitive. In view of the formation of HO• adducts, the C-N and N-N bond cleavages of the hydrazone tautomer of alizarin yellow R are also kinetically competitive, but the former is more thermodynamically favorable. This result is different from that previously reported for the hydrozone tautomers of Acid Orange 7 and Acid Orange 8 containing hydroxyl and azo groups in neighboring positions, which are favorable to follow C-N bond cleavage mechanism both kinetically and thermodynamically. The decarboxylation occurs via an attack of HO• to the benzene ring carbon connecting to the carboxyl group rather than a direct attack of HO• to the carboxyl carbon atom. The anion form has higher reactivity than the neutral form in all of the reactions investigated. In addition, a water molecule as a proton relay reagent could significantly reduce the energy barrier for the N-N bond cleavage of alizarin yellow R. Figure 2. Optimized structures (distances in Å) and relative energies in the solution for HO• attacking the C3 and C6 sites of AH to result in the cleavage of the C-N bond (energies in kcal/mol relative to the energy sum of AH and HO•) X. JIAO ET AL. wileyonlinelibrary.com/journal/poc a The energies are relative to the energy sum of AH (or A) and HO•. The AH_Ci_TS and AH_Ci_P (i = 1, 2, 17, 18 and 21, atom labeling shown in Chart 3) denote the HO• addition transition states and resulting adducts, respectively. The same is true for the A case. DFT STUDY ON DEGRADATION MECHANISM OF AZO COMPOUNDS

No abstract

Summary The trip setpoint parameters of a molten salt reactor have been analyzed by performing multiple linear regression (MLR) method. In the analysis, a reactivity‐initiated accident with inadvertent control rod withdrawal accident under low power condition was considered as the initiating event. A total of 285 cases located from 20 235 thermal‐hydraulic simulation runs have been divided into identification dataset (70%) and test dataset (30%) for MLR. MLR models show that the maximum fuel salt temperature and corresponding control rod extraction rate follow a quite convincing linear hypotheses relationship with trip setpoint parameters. Sensitivity analysis gives the sensitivity rankings of trip setpoint parameters. And the predictive values of three significantly influential trip setpoint parameters with different margin considerations have been acquired quantitatively.