Effects of phosphorus content on generation and growth of cracks in nickel–phosphorus platings owing to thermal cycling

We observed crack generation and structural changes in electroless nickel–phosphorus (Ni–P) plating layers formed on copper-metalized silicon nitride substrates both during thermal cycling from ? 40 to 250 °C and during storage (not cycling) at 250 °C in order to investigate the effect of the phosphorus contents on crack generation and growth in the Ni–P platings. The used platings contained phosphorus at three different contents: 2.1 wt% [Ni–P(low)], 6.5 wt% [Ni–P(med)], and 10.9 wt% [Ni–P(high)]. The generation time and the amount of cracks were strongly dependent on their phosphorus contents. More cracks appeared after thermal cycling than after storage at 250 °C. In Ni–P(low), cracks were generated after 200 thermal cycles, whereas no cracks were observed even after 250 h of storage at 250 °C. In Ni–P(med) and Ni–P(high), both during thermal cycling and storage at 250 °C, cracks formed during or after crystallization of the amorphous layers. These results suggest that the primary factors affecting the generation of cracks in electroless Ni–P platings are crystallization of the Ni–P platings and repeated changes in thermal stress.     

Cooperative Control by System Voltage Control Equipments in Consideration of Reducing Capacity of STATCOM

In recent years, the number of renewable energy sources (RESs) such as photovoltaic generation systems and wind power generation systems connected to the grid has been increasing as a way of reducing negative effects on the environment. The outputs of these RESs vary rapidly because of the influence of the weather and the conditions of the location. Therefore, there are concerns that the point voltages in a distribution system may vary drastically and that the voltages may deviate from the appropriate voltage range as a result of the influence of the RES connected to the distribution system or to the diversification of loads. Furthermore, there are concerns about adverse effects on electric power quality, such as voltage imbalances and harmonics. In this paper, we propose a cooperative voltage control method for a distribution system using system voltage control equipment in order to reduce the capacity of the static synchronous compensator. Numerical calculations were performed in order to verify the validity of the proposed method.     

Characterization of the Oxide Scale Formed on T12 Water Wall Tube After Long-term Service in Supercritical Power Plant

Oxidation of Metals - Oxide scale control is one of the critical maintenance issues in fossil fuel power plant. Hence, the water treatment of the feed water has been changed from all-volatile...     

Homogeneous Strain Introduction Using Reciprocation Technique in High-Pressure Sliding

Metallurgical and Materials Transactions A - This study examines strain distribution occurring in the high-pressure sliding (HPS) processing for rods of pure Al and an AZ61 alloy. The strain...     

Photoacoustic Spectroscopy of Some Energetic Materials

To find an effective laser source to ignite energetic materials, the absorption spectra of some energetic materials are obtained by means of a photoacoustic spectroscopy (PAS). In this experiment, PAS covers the wavelength region of 400 nm-1600 nm in which no other conventional method can take absorption spectra for powdered energetic materials. Photoacoustic spectra of 18 energetic materials are reported. In general, energetic materials tested showed peaks in 600 nm–800 nm and 1400 nm–1600 nm ranges. It is found that the energy required to initiate explosives in the case of ruby laser initiation were correlated with their photoacoustic signal intensities.     

Genetic Study of Four Candidate Holliday Junction Processing Proteins in the Thermophilic Crenarchaeon Sulfolobus acidocaldarius

Homologous recombination (HR) is thought to be important for the repair of stalled replication forks in hyperthermophilic archaea. Previous biochemical studies identified two branch migration helicases (Hjm and PINA) and two Holliday junction (HJ) resolvases (Hjc and Hje) as HJ-processing proteins; however, due to the lack of genetic evidence, it is still unclear whether these proteins are actually involved in HR in vivo and how their functional relation is associated with the process. To address the above questions, we constructed hjc-, hje-, hjm-, and pina single-knockout strains and double-knockout strains of the thermophilic crenarchaeon Sulfolobus acidocaldarius and characterized the mutant phenotypes. Notably, we succeeded in isolating the hjm- and/or pina-deleted strains, suggesting that the functions of Hjm and PINA are not essential for cellular growth in this archaeon, as they were previously thought to be essential. Growth retardation in Δpina was observed at low temperatures (cold sensitivity). When deletion of the HJ resolvase genes was combined, Δpina Δhjc and Δpina Δhje exhibited severe cold sensitivity. Δhjm exhibited severe sensitivity to interstrand crosslinkers, suggesting that Hjm is involved in repairing stalled replication forks, as previously demonstrated in euryarchaea. Our findings suggest that the function of PINA and HJ resolvases is functionally related at lower temperatures to support robust cellular growth, and Hjm is important for the repair of stalled replication forks in vivo.