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Substantial oxygen enrichment is observed in the natural air hydrates formed in Arctic and Antarctic ice sheets. Inspired by this phenomenon, a novel air separation method, utilizing hydrate crystallization, is proposed in our work. The three-phase equilibrium pressure for the air + water system is greater than 15 MPa as the temperature is upon ice point, which makes the air separation impractical by hydrate formation under mild temperature conditions. So, some additives were selected to reduce the phase equilibrium pressure of air hydrates at a fixed temperature. In this work, hydrate dissociation conditions for the air + tetrahydrofuran (THF) + water system (x = 0.0300 and 0.0500), the air + cyclopentane (CP) + water system (x = 0.0300 and 0.0556), and the air + tetra-n-butyl ammonium bromide (TBAB) + water system (w = 0.20 and 0.30) were measured in the temperature ranges of (279.7 to 290.5) K, (284.0 to 296.2) K, and (283.4 to 288.0) K, respectively. The comparison result shows that, in the pressure r...

The present study attempts to clarify the relative cytotoxic levels of ions, colloidal nanoparticles, and metallic particles found in wear-corrosion products of SUS317L stainless steel. The wear-corrosion products were generated in pin-on-plate wear tests in a calcium-magnesium-free phosphate buffered saline solution (PBS(−)). Of all the particles and ions generated by wear-corrosion, colloidal nanoparticles induced maximum cytotoxicity. Metallic particles were much better tolerated than colloidal nanoparticles. Levels of iron and chromium ions released into the PBS(−) solution were too low to induce cytotoxic effects. Cytotoxic effects due to nickel were still smaller than those due to the colloidal nanoparticles. These nanoparticles consisted mainly of phosphate-containing amorphous iron hydroxide formed by precipitation, and possibly mechanochemical reaction during wear-corrosion.

Electronic assembly technology is in the transition from traditional tin-lead to lead-free. In comparison with Sn-Pb solders, high melting point and poor wettability of the lead-free solders lead to great challenge to present electronic assembly technologies. Inert nitrogen atmosphere can both widen the process window of reflow and improve the mechanical reliability of solder joints. The focus of this study is to investigate the effect of reflow atmosphere on the reflow process and solder joint reliability of lead-free solders (SAC305). Board level reflow in various kinds of atmospheres and microstructural characterization of the solder joint were carried out to demonstrate the influence of controllable atmosphere on the reflow quality of the lead-free solder joints. The SAC305 solder joint fabricated in 1000 ppm O 2 exhibited a good surface morphology and an interface with very small pores. Surface finish of the solder pad was found to have a great influence on the as-reflowed solder joints.

This paper is about the evaluation of the extremely low microbial counts from the field by expanding the most probable number (MPN) methodology when the data follow Poisson distribution in order to achieve more accurate estimation with limited number of data. Several data sets with extremely low microbial counts from pharmaceutical clean room and laboratory clean bench monitoring were found with good Poisson distribution fitness by chi2 test (P0.05), and the MPN calculations were conducted for these data by using the Halvorson and Ziegler equation. The MPN values are generally larger than the arithmetic average, indicating a higher sensitivity of the data assay. This approach is justified because Poisson distribution is the mathematical background of the MPN procedure, with the Halvorson and Ziegler equation as its foundation. It is considered that the MPN methodology has a potential application for quality control in the extremely low level microbial counting environment in the clean rooms levels ISO class 7 or above. Further studies on the precision of this method and development of a sampling plan based on careful mathematical analysis will help to refine the approach.