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Modern technologies use NO(2) to promote low-temperature soot oxidation for diesel particulate filter regeneration. In this study, the online aerosol technique of high-temperature oxidation tandem differential mobility analysis is used to study kinetics of soot oxidation by NO(2). Soot particles are exposed to varying temperature and NO(2) mixing ratio inside the furnace resulting from thermal decomposition of NO(2) to NO. This causes soot oxidation rates to vary throughout the furnace. Variations in temperatures and NO(2) mixing ratio are thoroughly accounted for the first time. Soot oxidation rates are calculated as a function of frequency factor A(soot), activation energy E(soot), and concentration of NO(2) within the furnace at temperatures ranging from 500 to 950 degrees C. Results suggest A(soot) and E(soot) values for soot oxidation of 2.4 x 10(-14) (nm K(-0.5) s(-1) cm(3) molecule(-1)) and 47.1 kJ mol(-1), respectively, when reaction order to NO(2) is assumed as unity. The activation energy for soot oxidation with NO(2) is significantly lower than oxidation with air. However, parts per million levels of NO(2) cause soot oxidation at low temperatures suggesting NO(2) is a stronger oxidant than O(2).

As-received Gr.91 steel tube was normalized at either 940 or 1060 • C for 1 h, followed by Ar-assisted cooling to room temperature, then tempered at 760 • C for 2 h. Those samples were designated as 940NT or 1060NT samples. An infrared heating system was used to simulate HAZ microstructures in the weld, which included over-tempering (OT) and partial transformation (PT) zones. The results of short-term creep tests showed that normalizing at higher temperature improved the creep resistance of the Gr.91 steel. By contrast, welding thermal cycles would shorten the creep life of the Gr.91 steel. Among the tested samples in each group, the PT samples had the shortest life to rupture, especially the 940NT-PT sample. The microstructures of the PT samples comprised of fine lath martensite and ferrite subgrains with carbides decorating the grain and subgrain boundaries. Excessive dislocation recovery, rapid coalescence of refined martensite laths, and growth of ferrite subgrains were responsible for the poorer creep resistance of the PT samples relative to those of the other samples.

The calcium sulfate (CS) tablets exhibit excellent osteoinductive and osteoconductive characteristics, they can be used to repair bone defects. However, the degradation rate of CS tablets is very fast. The present study demonstrates, for the first time, that the degradation rate of CS tablets can be manipulated through the use of sintering technique. Firing the CS tablets to a temperature of 1100 • C increases their relative density to a value above 90%. The density can be further enhanced to above 95% through the addition of 1 wt% sintering additives. The sintered CS tablets with the addition of sintering additives exhibit a high strength and a low cytotoxicity. More importantly, the degradation rate is tunable through the choice of sintering additives.