The invention relates to methods for prevention of and recovery from a catalyst bed slumping in a gas-agitated multiphase hydrocarbon synthesis reactor, while the reactor is either under non-reactive conditions or under reaction promoting conditions when syngas is converted to products. This estimate of the filling factor is used to determine the margin available to load the refiner and the control action needed to avoid abnormal operation. The polymeric materials in accordance with the present invention can be modified with any desired functional group to tailor the polymer materials for a specific application. For oral administration, 20 mgkg of ALA is dissolved in 50 mL of a 5% glucose solution prior to the administration. The transition from the first stroke mode to the second stroke mode occurs independent of the operating condition of the engine throughout the entire operating range of the engine. The unitary system comprises a series of sequentially arranged topside, inside and bottom side regions having different properties needed to perform the functions of the absorbent article.