Control screening, second-level

Careful attention to such detail is necessary as a second line of defence against the effects of reactive hazards. The level of protection considered necessary may range from the essential and absolute minimum of effective eye protection, via the safety screen, fume cupboard or enclosed reactor, up to the ultimate of a remotely controlled and blast-resistant isolation cell (usually for high-pressure operations). In the absence of facilities appropriate to the assessed level of hazard, operations must be deferred until such facilities are available. 

Current applications of MS/MS for amino acids are predominantly for screening purposes, especially in newborns, and follow-up confirmatory tests are necessary. Transient tyrosinemia, for example, is quite common in the newborn, and follow-up is perhaps advisable only if clinically indicated, or if tyrosine levels remain elevated 2-3 weeks after birth. In most cases, the amino acid elevations are marked (>5x normal mean) and follow-up tests are ordered promptly, otherwise a repeat screen is ordered. Follow-up testing is not necessary if the second screen is normal. Sulfocysteine levels in affected patients are more than an order of magnitude higher than in normal controls. A summary of the amino acids for which validation of the MS/MS method has been carried out, and the disorders associated with their elevation, is provided in Table E.2. 

Four categories of durability wear tests are typically done for UHMWPE destined for a TKR application (1) pin-on-disk material screening tests, (2) force-control knee simulator tests, (3) displacement-control simulator tests, and (4) special damage mode simulation tests. The other (first three) categories will be described at varying levels of detail in this chapter. The second and third test methods will be preceded by describing some general considerations of the biomechanics of the knee, coordinate systems, and the physical variables involved. This will set the scene for a... 

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