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Yttria stabilized tetragonal zirconia polycrystal (Y-TZP) owes its high toughness to transformation toughening, a mechanism that requires the development of a process zone. It is important to measure if and to what extent the size of components can be reduced. In this study, tests were carried out using focused ion beam or picosecond milled pre-notched, 3 mol percent Y 2 O 3 (3Y-) TZP micro-cantilever (10–250 μm) beams. The tests show clearly that the maximum fracture resistance is size dependent and the plateau toughness was not reached in any of the small-scale samples. A correlation between transformability of the tetragonal phase and the measured fracture resistance became visible only for the largest micro cantilever but did not reach the values measured in macroscopic samples. Based on these results, it is not advantageous to use very tough zirconia materials in components with dimensions smaller than ∼0.25 mm, as the high toughness is not fully realized. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the performance characteristics of commercially available US foundry consumables for use in three-dimensional sand printers. The silica sands selected were 57 grain fineness number (GFN) and 70 GFN. These sands were a high-purity round grain silica and had low trace contaminates, to reduce any possible influence from contaminates. The furan resin system was selected since it is the most widely utilized resin system for 3D printed sand in the USA. The furan resin system was from a domestic US foundry supplier. The printed samples were traditional tensile specimen and rectangle samples for the determination of density. The samples were examined for the following properties: tensile strength, loss on ignition, density, scratch hardness, and permeability. The results of this investigation confirmed that the tested domestic resin system and silica sands matched the original equipment manufacturer performance properties. [ABSTRACT FROM AUTHOR]

Narcolepsy is a disabling neurological sleep disorder characterized by excessive daytime sleepiness and abnormal REM sleep manifestations. Recently, the role of cytokines and growth hormone in the regulation of sleep and narcolepsy has been considered, and data suggest that proinflammatory cytokines may be involved in sleep and narcoleptic symptoms. Serum and clinical data were obtained from the Stanford Center for Narcolepsy Research for 39 Narcoleptics (22 Females, 17 Males, age 39 ± 14.9) and 40 controls (13 Females, 27 Males, age 46 ± 17.9). Plasma levels of TNF-α, IL-6, and human growth hormone (hGH) were measured by ELISA. TNF-α and IL-6 were significantly increased in narcoleptic subjects compared to controls (p=.001). Interestingly, hGH was significantly increased in narcoleptic subjects (p<.0001). There was also a significant difference in the epworth sleepiness scale (ESS) (17.7 ± 4.6 vs. 5.5 ± 3.2, p<.0001). These data indicate that narcoleptics, relative to controls, had higher serum levels of TNF-α, IL-6, and hGH. These data suggest that the dysregulation of sleep observed in narcoleptics correlates with the immune and endocrine dysregulation seen in these subjects, and the observed changes may in fact contribute to the higher likelihood of disturbed sleep and/or increased incidence of infection. Additional work is required to fully characterize connections between cytokines and narcoleptic symptomatology. [Copyright &y& Elsevier]

Eutectic NiAl-(Cr,Mo) composites are promising high temperature materials due to their high melting point, excellent oxidation behavior and low density. To enhance the strength, hardness and fracture toughness, high cooling rates are beneficial to obtain a fine cellular-lamellar microstructure. This can be provided by the additive process of selective electron beam melting. The very high temperature gradient achieved in this process leads to the formation of the finest microstructure that has ever been reported for NiAl-(Cr,Mo) in-situ composites. A very high hardness and fracture toughening mechanisms were observed. This represents a feasibility study towards additive manufacturing of eutectic NiAl-(Cr,Mo) in-situ composites by selective electron beam melting. [ABSTRACT FROM AUTHOR]