Finding the 14C age of a contemporaneous terrestrial sample was challenging for all instances where reservoir ages were calculated: Modern samples are affected by bomb carbon [46, 47], while not all ancient aquatic samples are clearly associated with terrestrial samples.
Anti-endotoxin antibody was added to the first sample to aid in the measurement of endotoxin, then the second sample is challenged with a maximum stimulatory dose of endotoxin (800pg/ml) to allow endotoxin quantitation and measure the state of neutrophil activation is assessed by the maximal chemiluminescent response.
However, if the reference data are complicated and do not cluster according to their annotation, classification of the outside sample is challenging if not impossible.
The quality of the provided specimens may have been suboptimal because instructing and motivating persons to provide a sputum sample is challenging.
Sandstone and carbonate core samples were challenged with a two-phase supercritical CO2 and brine mixture to investigate the effects of chemical processes on the physical properties of these rocks during injection of CO2.
Samples were challenged by exposure to both direct and gradual low temperature after culture in the laboratory at 20°C.
Translating this approach for laboratories that analyze clinical samples is challenged by quality issues with human tissue RNA.
Tissue samples were challenged with HIV-1BaL (250 ng/mL), spinocculated for 2 hours at 37°C, washed four times, transferred to six-well tissue culture plates, and cultured.
The selective study of 4q-located D4Z4 repeats in human samples is challenged by the presence of D4Z4-like sequences on almost all human acrocentric chromosomes (Lyle et al., 1995; Winokur et al., 1994).
The analysis and determination of N-nitrosamines (NAs) in water samples are challenging and demanding.
