ABSTRACTΤhe extreme weather conditions in Middle East Area led to the construction of tightly sealed, air conditioned buildings, characterized by indoor air quality deterioration. This study presents the results of chemical characterization of outdoor and indoor PM 2.5 and PM 10 in Doha city, over a two-month period including normal days and dust events, aiming at identifying the factors affecting the indoor air of an office building. The WHO guideline values were exceeded in 100% of the outdoor measurements. 49% of the days of the sampling campaign were characterized as non-dusty (PM 10 < 200 µg m ). The contribution of both dust and anthropogenic emissions sources is depicted in particles' mass and chemical composition. The elevated -especially outdoor-levels of carbonate carbon indicate the presence of crustal matter originating from the surrounding crustal material. OC/EC values reveal possible combined contribution from secondary organic aerosol, trafficrelated sources and re-suspended dust. The influence of anthropogenic emissions is implied by the predominance of nitrate and sulfate ions, which constitute a substantial percentage of the particle mass. The crustal origin of particles is also depicted in metals. However, the higher enrichment factor values which may imply anthropogenic activities of both the outdoor and indoor environment were determined sequentially for Cd, Pb, As, Cu and Zn, suggesting the role of infiltration. Concluding, the indoor to outdoor relationship is significantly influenced by particles infiltration and penetration into the building mainly through the ventilation system and to a lesser extent, through windows or cracks in the building envelope. Although the low indoor to outdoor ratio underlies the predominance of outdoor levels compared to the indoor ones, there is positive correlation between indoor and outdoor PM, during the days that the building was open to the public and employees.

The effects of lamination and changes in the laminae thickness on the fatigue-crack propagation of 6090/SiC/25p-6013 laminates tested in the crack-arrestor orientation were investigated. The fatiguecrack propagation behavior of the individual monolithic and discontinuously reinforced aluminum alloy (DRA) layers was compared to that of the laminates. The fatigue behavior of the laminates was different than that of the individual laminae and was affected by changes in the layer thickness. In-situ monitoring of fatigue-crack growth and postmortem analyses were used to determine the likely source(s) of the layer-thickness effect and differences between the laminated metal composites (LMCs) and its constituents.

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The effects of changes in loading rate and test temperature on the fracture toughness of a Zr-based bulk metallic glass (BMG) were investigated under both displacement-rate-controlled and loading-rate-controlled conditions in three-point bending. The tests were conducted at displacement rates ranging from 0.01 to 10 mm/min, loading rates ranging from 31.5 to 5700 lb/min, and test temperatures from room temperature (298 K) to 623 K. Significant effects of test temperature on the toughness were obtained, while testing under displacement rate control vs loading rate control also produced differences in the toughness and fracture morphology. A preliminary fracture mechanism map is provided to illustrate the effects of changes in temperature and strain rate on the toughness normalized with room-temperature values.