Identify a true statement about gestures.

Questions

Identify а true stаtement аbоut gestures.

Prоblem 3  A biоfilm is а lаyer-like аggregatiоn of microscopic organisms, plant or bacteria attached to a solid surface. Biofilms are found in or on stream-beds, ground-water aquifers, water pipes, ship hulls, piers, and aquatic plants and animals. Engineered processes that utilize biofilms include trickling filters, biologically activated carbon beds, and land treatment systems. Biofilms can also build up on biomedical instruments, making it difficult to sterilize them.  For simplicity, here we will consider such a biofilm where a reactant (designated as A) diffuses through the biofilm. The reactant A is consumed only at the solid surface (x = L) and this consumption is represented by a constant flux of A equal to at the surface of the solid catalyst. Assume that the biofilm thickness is 0.01 cm and the diffusivity (DAB) of the reactant in the biofilm is 0.8 cm2/day. The reactant concentration in the biofilm in contact with the bulk fluid is uniform at 3.2 mg/liter (See the schematic below). Do the following (assume that the system is at steady state.)  Starting from the most general partial differential equation for mass transfer, derive the ordinary differential equation (ODE) that you will solve for the system. Determine the general solution of the final ODE in (a). What are the boundary conditions? From the boundary conditions in (c), solve for the constants of integration in (b) (Express the constants in terms of the symbols, then plug in their given values). What is the equation for CA as a function of position x in the biofilm? Calculate the concentration of A at the solid surface, CAL , in mg/L.Note: 1 liter = 1,000 cm3