Effect of the specific activity of the tracer on rat luteinizing hormone radioimmunoassay

Rat luteinizing hormone /LH/ was labelled with¹²⁵I by the Chloramine T method.¹²⁵I-LH, used as tracer in radioimmunoassay, was separated from the labelling reaction mixture by gel filtration. By using the proper protein/radioiodine ratio in the labelling reaction mixture the specific activity of¹²⁵I-LH was adjusted to 2.5–20.5 MBq g^–1. The influence of the specific activity on the assay parameters as well as on the tracer stability was investigated.     

Oscillatory and stationary convective patterns in a reaction driven gravity current

Horizontally propagating chemical fronts are studied in a thin solution layer of the acid-catalyzed chlorite-tetrathionate reaction. Unusual cellular patterns develop when significant amount of autocatalyst is bound to polyelectrolyte with low mobility: both oscillatory and stationary patterns evolve as a result of the interaction between the reaction front and the superposed gravity current. The concentration of the polyelectrolyte regulating the velocity of front propagation serves as a bifurcation parameter for switching between the two basic patterns.