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Oxidation corrosion of steel is a universal problem in various industries and severely accelerated in nuclear reactors. First-principles calculations are performed to explore the dissolution and diffusion properties of interstitial oxygen in the body-centered-cubic iron grain boundaries Σ3〈110〉(111) and Σ5〈001〉(310). Solution energies indicate that interstitial oxygen atoms prefer to dissolve in body-centered-cubic iron, and energetically segregate to grain boundaries. Energy barriers show that oxygen atoms would segregate towards Σ3〈110〉(111) with a low energy barrier. However, they concentrate to the transition region of Σ5〈001〉(310) due to the high-energy barrier in the transition zone. When O atoms arrive at grain boundaries, they would stay there due to the larger solution energy and diffusion energy barrier in grain boundaries compared to that in the defect-free Fe bulk. These results indicate that O atoms would prefer to diffuse through the bulk, and oxidize grain boundaries. This study provides insight into oxidation phenomena in experiments and necessary parameters for future studies on the oxidation of steel under irradiation in nuclear reactors.

Intermetallic alloy ZrCo is a good material for storing tritium (T). However, ZrCo is prone to disproportionation reactions during the process of charging and discharging T. Alloying atoms are often added in ZrCo, occupying the Zr or Co site, in order to restrain disproportionation reactions. Meanwhile, T often decays into helium (He), and the purity of T seriously decreases once He escapes from ZrCo. Therefore, it is necessary to understand the influence of alloying atoms on the basic stability property of He. In this work, we perform systematical ab initio calculations to study the stability property of He in ZrCoH3 (ZrCo adsorbs the H isotope, forming ZrCoH3). The results suggest that the He atom will undergo displacements of 0.31 and 0.12 Å when it substitutes for Co and Zr, respectively. In contrast, the displacements are very large, at 0.67–1.09 Å, for He replacing H. Then, we introduce more than 20 alloying atoms in ZrCo to replace Co and Zr in order to examine the influence of alloying atoms on the stability of He at H sites. It is found that Ti, V, Cr, Mn, Fe, Zn, Nb, Mo, Tc, Ru, Ta, W, Re, and Os replacing Co can increase the substitution energy of H by the He closest to the alloying atom, whereas only Cr, Mn, Fe, Mo, Tc, Ru, Ta, W, Re, and Os replacing Co can increase the substitution energy of H by the He next closest to the alloying atom. The influence of the alloying atom substituting Zr site on the substitution energies is inconspicuous, and only Nb, Mo, Ru, Ta, and W increase the substitution energies of H by the He closest to the alloying atom. The increase in the substitution energy may suggest that these alloy atoms are conducive to fix the He atom in ZrCo and avoid the reduction in tritium purity.

In order to reduce the computational costs, this paper investigates the event-triggered control design for the uniform finite-time sampled-data set stabilization of switched delayed logical control networks (SDLCNs). Firstly, by the augmented algebraic form of SDLCNs, the uniform finite-time sampled-data controllability matrix is constructed, based on which, the uniform finite-time sampled-data reachable sets are defined. Secondly, using the reachable sets, a necessary and sufficient condition is proposed for the set stabilization of SDLCNs. Thirdly, the event-triggered control design is presented, and a sufficient condition is proposed to design the state feedback event-triggered control for the sampled-data set stabilization of SDLCNs. Finally, an example is given for the verification of main results.

This paper investigates the stability and uniform sampled-data stabilization of state-dependent delayed Boolean networks (SDDBNs) with state constraints. Firstly, the dynamics of SDDBNs with state constraints is converted into an algebraic form by using the semi-tensor product of matrices. Secondly, based on the algebraic form, a necessary and sufficient condition is presented for the stability of SDDBNs with state constraints. Thirdly, based on the trajectory constrained sampled-data con-trollability, a necessary and sufficient condition is presented for the state feedback sampled-data stabilization of state-dependent delayed Boolean control networks (SDDBCNs) with state constraints. Finally, an example is worked out to show the effectiveness of the obtained new results.

Neutron irradiation induces a large number of vacancies and self-interstitial atoms (SIAs) that interact with hydrogen atoms (H) and degrade the mechanical properties of tungsten (W) in a fusion environment. Vacancies increase free space and trap H atoms, however, the effects of SIAs on trapping H atoms are still unclear since SIAs decrease free space. We therefore perform systematical \emph{ab initio} calculations to study the interactions of SIAs and SIAs clusters with H atoms in W. Our results suggest that SIA $\langle111\rangle$ dumbbell makes interstitial H atoms easy to accumulate in W. With accumulation of H atoms near a SIA $\langle111\rangle$ dumbbell, the binding energy decreases firstly and then levels off at about 0.3 eV. For comparison, the interactions of SIAs and SIAs clusters with helium (He) atoms are considered. It is found that SIAs and SIAs clusters can also act as trapping centers for interstitial He atoms. The combinations of SIAs with H and He hinder the fast movement of SIAs in W to annihilate with vacancies, increasing the concentrations of SIAs and vacancies in grain. SIAs and vacancies provide more sites for trapping H and He atoms and thus increase irradiation damage in W. We therefore suggest reducing retention of H isotopes and He in W to suppress irradiation damage.