[en] Highlights: • Flow instability experiment between two heated channels with supercritical water is carried out. • Two kinds of out of phase flow instability are found and instability boundaries under different working conditions are obtained. • Dynamics characteristics of flow instability are analyzed. - Abstract: Super critical water reactor (SCWR) is the generation IV nuclear reactor in the world. Under normal operation, water enters SCWR from cold leg with a temperature of 280 °C and then leaves the core with a temperature of 500 °C. Due to the sharp change of temperature, there is a huge density change in the core, which could result in potential flow instability and the safety of reactor would be threatened consequently. So it is necessary to carry out relevant investigation in this field. An experimental investigation which concerns with out of phase flow instability between two heated parallel channels with supercritical water has been carried out in this paper. Due to two INCONEL 625 pipes with a thickness of 6.5 mm are adopted, more experimental results are attained. To find out the influence of axial power shape on the onset of flow instability, each heated channel is divided into two sections and the heating power of each section can be controlled separately. Finally the instability boundaries are obtained under different inlet temperatures, axial power shapes, total inlet mass flow rates and system pressures. The dynamics characteristics of out of phase oscillation are also analyzed

[en] A hybrid composite of Li_1_._2Mn_0_._5_4Ni_0_._1_3Co_0_._1_3O_2 nanotubes (LMNCO NTs) wrapped with reduced graphene oxide (RGO) nanosheets (LMNCO@RGO) was prepared as cathode for lithium-ion batteries. The discharge capacity of the LMNCO@RGO composite is only reducing 3.5% after 100 cycles at 1 C. Such composite which simultaneously combines a high surface area of LMNCO NTs with shorten ionic diffusion pathway and high conductivity of 3D graphene hierarchical architectures as well as structural protection layers, displaying a good cycling stability.

[en] The comparison of the effects on tribological property modification of martensitic H 13 steel implanted by several ions of Si, Ti and N (including Si or Ti followed by N) is made. Friction force measurements during unlubricated pin-on-disc sliding tests, profilometry and SEM analysis of wear tracks are used to determine the wear behavior quantitatively and qualitatively. N⁺ implantation show little reduction in friction and wear rate. Si⁺ implantation and Si⁺ + N⁺ dual implantation noticeably improved in both friction and wear performance. Ti⁺ implantation and Ti⁺ + N⁺ dua implantation are found to excellently reduce friction coefficient and wear rate by a factor of 2 and nearly 2 orders of magnitude respectively. The composition and microstructure changes in implanted layers are studied by using AES and TEM techniques. The mechanisms of ion implantation by N⁺, Si⁺ and Ti⁺ induced tribological improvement, composition and microstructural changes are also discussed

[en] Based on the principle of biostatistics, the literatures of low-energy ion beam induced organism aberrance were analysed. Firstly, the processes of data analysis in the selected articles were analysed in the view of biostatistics, and the deficiencies were pointed out, such as too small treated colony, deficiency with repication design in the experiment, faulty in variance analysis and deficiency with offspring study and so on. The suggestion for future research in this field were also listed in the paper. (authors)

[en] Based on the nuclear strategies and technical plans, Japan, Europe, Canada, Russia, China and other countries are devoted to the R&D of the supercritical water cooled reactor (SCWR) technology and have achieved lots of progress. This paper summarizes the international activities of SCWR from the view of the system development, discusses the outline of the participation of China in GIF-SCWR and its future plan, and provides some constructive suggestions for further development of SCWR R&D in China. (authors)

[en] Up to now, the traditional turbulence model evaluation in supercritical water still has some uncertainties to some degree. The basic reason is the limit of model itself which makes the model depend on the calculation parameters. This paper focuses on the turbulence model evaluation based on the batch process techniques of CFD tools through comparing with the experimental data base. Some typical turbulence models were analyzed against the experiments. The performance of each model was evaluated based on the statistical method. The dependencies of the performance on operation conditions were discussed. (authors)

[en] The wet etching properties of a HfSiON high-k dielectric in HF-based solutions are investigated. HF-based solutions are the most promising wet chemistries for the removal of HfSiON, and etch selectivity of HF-based solutions can be improved by the addition of an acid and/or an alcohol to the HF solution. Due to densification during annealing, the etch rate of HfSiON annealed at 900 ⁰C for 30 s is significantly reduced compared with as-deposited HfSiON in HF-based solutions. After the HfSiON film has been completely removed by HF-based solutions, it is not possible to etch the interfacial layer and the etched surface does not have a hydrophobic nature, since N diffuses to the interface layer or Si substrate formation of Si-N bonds that dissolves very slowly in HF-based solutions. Existing Si-N bonds at the interface between the new high-k dielectric deposit and the Si substrate may degrade the carrier mobility due to Coulomb scattering. In addition, we show that N₂ plasma treatment before wet etching is not very effective in increasing the wet etch rate for a thin HfSiON film in our case. (semiconductor technology)

[en] A novel dry etching process of a poly-Si/TaN/HfSiON gate stack for advanced complementary metal-oxide-semiconductor (CMOS) devices is investigated. Our strategy to process a poly-Si/TaN/HfSiON gate stack is that each layer of gate stack is selectively etched with a vertical profile. First, a three-step plasma etching process is developed to get a vertical poly-Si profile and a reliable etch-stop on a TaN metal gate. Then different BCl₃-based plasmas are applied to etch the TaN metal gate and find that BCl₃/Cl₂/O₂/Ar plasma is a suitable choice to get a vertical TaN profile. Moreover, considering that Cl₂ almost has no selectivity to Si substrate, BCl₃/Ar plasma is applied to etch HfSiON dielectric to improve the selectivity to Si substrate after the TaN metal gate is vertically etched off by the optimized BCl₃/Cl₂/O₂/Ar plasma. Finally, we have succeeded in etching a poly-Si/TaN/HfSiON stack with a vertical profile and almost no Si loss utilizing these new etching technologies. (semiconductor technology)

[en] Wet-etch etchants and the TaN film method for dual-metal-gate integration are investigated. Both HF/HN O₃/H₂O and NH₄OH/H₂O₂ solutions can etch TaN effectively, but poor selectivity to the gate dielectric for the HF/HNO₃/H₂O solution due to HF being included in HF/HNO₃/H₂O, and the fact that TaN is difficult to etch in the NH₄OH/H₂O₂ solution at the first stage due to the thin TaO_xN_y layer on the TaN surface, mean that they are difficult to individually apply to dual-metal-gate integration. A two-step wet etching strategy using the HF/HNO₃/H₂O solution first and the NH₄OH/H₂O₂ solution later can fully remove thin TaN film with a photo-resist mask and has high selectivity to the HfSiON dielectric film underneath. High-k dielectric film surfaces are smooth after wet etching of the TaN metal gate and MOSCAPs show well-behaved C-V and J_g-V_g characteristics, which all prove that the wet etching of TaN has little impact on electrical performance and can be applied to dual-metal-gate integration technology for removing the first TaN metal gate in the PMOS region. (semiconductor technology)

[en] DR1709 is a predicted Mn²⁺ transporter in Deinococcus radiodurans(D. radiodurans). The mensuration method to evaluate protein viability with two-dimensional electrophoresis in D. radiodurans and the mutants was established in this study. The results showed that after DR1709 was disrupted, the expressions of DR1120 (acetokinase), DR1691 (heat shock protein), DR1485 (putative lipase), DR2095 (putative c-type cytochrome) and other three hypothetical proteins (DR0124, DR0047 and DR2474) were repressed. However the expression of DR1794 (putative nosX) was induced. Phenomena above suggested that the increased radiation-sensitivity of the mutant cells may be attributed to not only the protection of gene DR1709, but also the proteins' different expressions between the wild type and the mutant might also play important roles in protecting D. radiodurans from irradiation. Although DR2095 was a homologue of c-type cytochrome, it has no realistic functions. (authors)