You are designing a medical device to collect

Carcinoembryonic Antigen (CEA, MW = 180,000 g

mol^-1), a tumor marker, from patients in order to create a personalized cancer vaccine. In this medical device, the cellular components of the blood are removed from the plasma. The plasma then flows into an extraction chamber. Within this chamber, the fluid flow divides into 48,000 10-cm long tubes with an inside diameter of 175 um. The surface of each tube is coated with a material that very rapidly adsorbs CEA. Plasma containing 6.1 ug m1^-1 of CEA flows into the chamber at 125 ml min^-1. Assume that the fluids are at body temperature (37°C). The viscosity and density of water at 37°C are 0.691 cP and 0.993 g/ cm^3, re-spectively. The diffusivity of CEA inside the extraction chamber is 6.1 × 10^-6 cm^2/s and the mass transfer coefficient for CEA inside the device is: k = 1.25 × 10^-5 cm s^-1.

Estimate the diffusivity of CEA within the extraction chamber?

What is the mass transfer coefficient (cms^-1) for CEA inside the device?

If you run the extraction for 1 hour and extract 31.7 mg of CEA, what must be the concentration of CEA in the device exit?

A new implantable drug delivery device is being developed in your lab. The device prototype is a very thin strip (0.1mm × 1mm × 15mm) of polymer coated on both sides with 22 milligrams of solid drug particles. To test the drug delivery profile, you "implant the device by suspending it in a homogenous model fluid that has following:

      Properties: viscosity = 0.0018 Pa.s, density = 1.32 g , temperature = 37°C. The diffusivity of the drug is estimated to be .

1. After 15 minutes, what do you expect the concentration of the drug to be at 1 mm from the device?

2. Determine how far the drug would penetrate into the fluid in 2.2 hours.

3. Clearly explain how you would determine the flux of drug at the surface of the device 10 minutes after implantation. Provide relevant assumptions, equations, and any other information that would be required for your solution.

Many biological tissues have layers with different extracellularmatrix components and different orientations of these components.As a result, diffusion coefficients vary from region to region(Even within a region, the diffusion coefficient depends upon thedirection of transport, a situation known as anisotropy). Considerthe steady-state, one-dimensional diffusion of a protein across atissue that consist of an acellular and a cellular phase. There areno chemical reactions. An example of such a tissue is an elasticartery that contains an elastic lamina of thickness L1 and a layerof smooth muscle cells of thickness L2 (actually, an arteryconsists of repeating layers of elastin and smooth muscle cells,but for the present discussion, consider a single layer of each).The protein diffusion coefficients of the two layers are Di1 andDi2, respectively. The concentration of the protein at the surface(x=0) is C1 = Φ1 * C0, and the concentration at x = L1 + L2 = L isC2 = Φ * CL. Determine the concentration as a function of positionx and the flux across the tissue. Show that the equation of fluxreduces to the equation of flux through a single layer when Di1 =Di2.

1. You are an ecologist interested in energetics of ecologicalsystems. You begin your current research program with a study ofprimary productivity of corn plants growing in a field in Iowaduring mid-summer. At noon on a sunny day, you enclose a singleleaf (still attached to the plant) in a transparent chamber. Thechamber is connected to a measurement device called an infrared gasanalyzer, which is capable of measuring minute changes in theconcentration of carbon dioxide (CO2) of the atmosphere within thechamber. The chamber is also maintained at a constant 30°C (same asthe outside air temperature) during your observations. You firstexpose the corn leaf to full sunlight and observe that CO2 is beingdepleted by the leaf from the chamber at a rate of 18 mg CO2 per100 cm2 leaf area per hour. You then cover the chamber withaluminum foil to exclude all light and observe that CO2 is beingreleased by the leaf into the chamber at a rate of 3 mg CO2 per 100cm2 leaf area per hour.

Questions

What is the rate of net primary productivity for this leafduring the measurement period (In mg CO2 per 100 cm2 leaf area perhour)? What is the rate of respiration for this leaf (same units asabove)? What is the rate of gross primary productivityfor this leaf (same units as above)? At this site, cornis planted at a density that results in 75% of the surface beingcovered by leaves. What is the total net primary productivity forone hectare of this corn field (in g C per hectare per year)?Assume that day length averages 12 hours per day over the course ofa 180 day growing season and that your measurement isrepresentative of the NPP for the entire growing season. Show yourcalculations.