Period attributions of specimens

Table I. Locations of Ancient Near Eastern Archaeological Sites and Period Attributions of Specimens Examined...

Specimens that are analyzed for QC purposes are called control materials. They are required to be stable, available in aliquots or vials, and amenable to being analyzed periodically over a long time. There should be little vial-to-vial variation so that differences between repeated measurements are attributed to the analytical method alone. The control material should preferably have the same matrix as the test specimens of interest (e.g., a protein matrix may be best when serum is the test material to be analyzed by the analytical method) Materials from human sources have generally been preferred, but because there is some risk of hepatitis infection, bovine materials offer a certain advantage in safety and are more readily available. The concentration of analyte should be in the normal and abnormal ranges, corresponding to concentrations that are critical in the medical interpretation of the test results. 

The simplest test used to study the deformation behaviour of asphalts was the static unconfined uniaxial compression test, termed the creep test, developed in the 1970s by Shell Bitumen (Hill 1973). The specimen was subjected to static axial compressive load over a long period (1 h). The test procedure was very simple and required low-cost equipment. In addition. Shell Bitumen developed a rut prediction procedure based on results of the creep test but soon realised that it underestimated rut depths measured in trial pavements (Hill et al. 1974). This was attributed to the effects of dynamic loading producing higher deformation in the wheel-tracking test (Van de Loo 1974). 

The specimens exposed from 00 15 to 08 15 corroded more than the others. The authors attributed the effect to condensation of dew, probably contaminated with industrial pollutants, on the surfaces in the early morning hours. It is interesting to note that the cumulative average corrosion rate of the three 8-hour periods was exactly the same as that obtained for the specimens exposed continuously. 

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