[en] Strong electronic stopping of high energy and high degree of ionization ions can lead to Coulomb explosion in which electron stripping causes repulsive interaction among positively charged atoms along ion tracks. Using molecular dynamics simulations and introducing an ionization pulse which lasts for different time periods, Coulomb explosion and structural evolution up to a time scale of 30 ps were modeled in SiC. The time periods of ionization pulses play an important role to determine radius of melting/amorphous regions after structural relaxation. For a long ionization, the amorphous/melting region can expand and become larger than the originally ionized region, while the opposite is observed for short ionization. (authors)

[en] Oxide dispersed strengthened (ODS) steel is an important candidate for Gen-IV reactors. Oxide embedded in Fe can help to trap irradiation defects and enhances the strength of steel. It was observed in this study that the size of oxide has a profound impact on the depinning mechanism. For smaller sizes, the oxide acts as a void; thus, letting the dislocation bypass without any shear. On the other hand, oxides larger than 2 nm generate new dislocation segments around themselves. The depinning is similar to that of Orowan mechanism and the strengthening effect is likely to be greater for larger oxides. It was found that higher shear deformation rates produce more fine-tuned stress-strain curve. Both molecular dynamics (MD) simulations and BKS (Bacon-Knocks-Scattergood) model display similar characteristics whereby establishing an inverse relation between the depinning stress and the obstacle distance. It was found that (110)_oxide II (111)_Fe (oriented oxide) also had similar characteristics as that of (100)_oxide II (111)_Fe but resulted in an increased depinning stress thereby providing greater resistance to dislocation bypass. Our simulation results concluded that critical depinning stress depends significantly on the size and orientation of the oxide

[en] Strong electronic stopping of high energy ions can lead to Coulomb explosion in which electron stripping causes repulsive interaction among positively charged atoms along ion tracks, if the ionization time is long enough. Using molecular dynamics simulations and introducing an ionization pulse which lasts for different time periods, Coulomb explosion and sputtering from the free surface were modeled in Si. The main issues include analyzing the number of sputtered atoms variation with ionization time, comparing the surface sputtering phenomenon caused by Coulomb explosion with different intensity and finding the Coulomb explosion strength which is not enough to cause sputtering. The results show that: At the beginning of the Coulomb explosion, sputtering phenomenon is obvious and the number of sputtering atoms on the surface keep growing, but latter the number of sputtering atoms fluctuated because of the attractiveness of atoms inside; Different ionization time different sputtering phenomenon, the longer the ionization time, the more violent the explosion, the more sputtering atoms; If the ionization time last only 6 fs, there will not be sputtering atoms by Coulomb explosion. (authors)

[en] Understanding oxygen interstitial cluster kinetics in U0₂ material under strain condition is important for radiation damage effect and improvement in nuclear fuel. By means of molecular dynamics, we simulate diffusion phenomena of interstitial cluster composed of two O atoms under 3% strain along <001> axial with different temperatures. The results show that, the diffusion of O interstitial cluster is mainly along the strain direction; higher the temperature, more collisions between O interstitials and lattice atoms and more distance O interstitial cluster diffusion in the same tame interval; using Einstein equation and Arrhenius equation, the diffusion energy is 0.9192 eV. (authors)

[en] By means of molecular dynamics, diffusion behaviors of oxygen dumbbell interstitial defect in UO₂ were simulated under the influences of tensile strain direction and tensile strength with different substrate temperatures. The diffusion of oxygen dumbbell interstitial defect is three-dimensional, and the ability of diffusion is relation to substrate temperature and tensile strength. Using simulation results, the diffusion coefficient of oxygen dumbbell interstitial defect was conformed. From the simulation, oxygen dumbbell interstitial defect is always arranged in <111> direction during diffusion process, higher temperature and larger tensile strain, more obvious the diffusion becomes, especially with increasing tensile strength along <111> axial, the direction of diffusion is mainly along <100> axial under strain or not. The results provide the basis for the study to radiation damage effects in UO₂. (authors)

[en] Objective: To create a further understanding of the angiographic features of the carotid artery pseudoaneurysm (CAPA) and to explore the clinical diagnostic value of angiography. Methods: Sixteen cases of CAPA with clinical and angiographic data were analyzed retrospectively. The angiographic appearances in all of the patients were observed dynamically and precisely with a double blind method by two experienced radiologists together and formed a consensus interpretation. Results: Angiography provided a definite diagnosis for all cases. The parent arteries included the common carotid artery (1 case), common carotid artery bifurcation (9 cases), internal carotid artery (5 cases) and external carotid artery (1 case). The angiographic features of the CAPA were: All cases showed the contrast media retension in the aneurysms; turbulent flow within aneurysm in 9 cases; the 'jetting sign' at the leak of the parent artery in 7 cases; increase angulation of the bifurcation of internal and external carotid arteries in 12 cases. Conclusions: Angiography is the most valuable examination method in diagnosis of CAPA, and it can not only provide definite diagnosis, but also play an important role in selection of therapeutic plan. (authors)

[en] The development of nuclear technology is closely and inseparably related to the improvements of materials irradiation performance. The irradiation damage of nuclear materials is an important issue of characteristics and difficulties. Because of the excellent features, SiC becomes one of the candidate materials for the cladding material and structure material in fast neutron reactor and fusion reactor. As one of the polytypes, 4H-SiC has prospective important applications in a strong irradiation environment. In this work, molecular dynamics (MD) simulation was performed to study the irradiation-induced cascade damage in single-crystalline 4H-SiC to get the microscopic evolution during the irradiation, in the aim of getting access to the detail that we cannot get from experiments. The software LAMMPS was used to simulate the damage formation process and the recovery process. The results showed that the initial project direction, the temperature and PKA energy exerted significant effects on the number and morphology of defects. (authors)

[en] In order to detect dynamic deflection rapidly and continuously, a dynamic model under traffic load of asphalt pavement finite element was built, dynamic deflection with different traffic speeds and different point were studied; the dynamic deflection with different thickness of pavement layers and different dynamic modulus were also studied. Results show that the dynamic deflection is different with different traffic, the higher the speed the smaller the deflection, and the maximum deflection lags the peak traffic loads; road pavement thickness increased significantly reduced dynamic deflection, the order of thickness impact dynamic deflection was the surface layer, the base and subbase; the layers modulus increases the dynamic deflection reduced. Findings contribute to developing continuous and rapid dynamic deflection testing equipment based on dynamic deflection characteristics of the road surface. (paper)

[en] Oxide-dispersed-strengthened (ODS) steel has excellent mechanical, thermodynamic and radiation resistant properties, which makes it an important candidate material for high-temperature reactors applications. Radiation stability of oxide is very important to study at the atomic level. In present case molecular dynamics (MD) simulation is used to study stabilities of Y₂O₃ particles in ODS steel as a function of particle sizes. The size dependence is obvious for particle sizes larger than 2.8 nm. Furthermore, the stabilities depend on charges of Y and O atoms. (paper)

[en] Silicon as a high capacity alloying anode material in lithium-ion batteries (LIBs) has recently been reported to have a promising specific capacity suitable for sodium-ion batteries (SIBs). However, the low gravimetric capacity and large volume expansion in traditional electrodes arising from the slurry-coating process has restrained the development. Here, we report the fabrication of a self-supported composite composed of silicon nanocrystals in a 3D hierarchical carbon network as an anode for reversible sodium storage by a three-step process involving electrostatically assisted hetero-assembly, vacuum filtration, and thermal treatment. The silicon nanocrystals decorated with a carbon coating are dispersed in interconnected carbon nanotubes with close contact. The structure provides abundant interfacial active sites for capacitive Na storage. Furthermore, the conductive 3D network of carbon nanotubes and carbon coating provide the high-speed pathways for charge transport and buffer to accommodate the volume change during Na⁺ insertion/extraction in silicon nanocrystals. As a binder-free anode in SIBs, the self-supported electrode delivers outstanding electrochemical performance such as stable cyclability with a capacity of 80% at a current density of 0.2 A g⁻¹ after 1000 cycles and high-rate capability with a capacity of 105 mAh g⁻¹ at a current density of 2 A g⁻¹. The self-supported Si-based electrode has great potential in high-performance SIBs.