Engineering, 20.05.2021 20:20 mem81
Consider a drug-eluting balloon catheter deployed into a blood vessel. The balloon is inflated to perfectly adhere to the vessel walls. Drug is released from the outer surface of the balloon and diffuses radially through the endothelial tissue only in the r-direction. Let the outside radius of the balloon be r = R_0, where the drug has a constant concentration c_0. The drug diffuses into the tissue as far as r = R, where the concentration of the drug becomes zero.
Assume cylindrical geometry, steady state conditions and no chemical reaction involving the drug. The drug diffusion coefficient in tissue is D.
(a) Find an expression for the profile c(r) inside the tissue (i. e. from R_0 to R).
(b) Determine the diffusive flux at the outer surface of the balloon.
Answers: 1
Engineering, 03.07.2019 14:10
Amass of 1.5 kg of air at 120 kpa and 24°c is contained in a gas-tight, frictionless piston-cylinder device. the air is now compressed to a final pressure of 720 kpa. during the process, heat is transferred from the air such that the temperature inside the cylinder remains constant. calculate the boundary work input during this process.
Answers: 2
Engineering, 04.07.2019 18:10
Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.
Answers: 1
Engineering, 04.07.2019 18:10
Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?
Answers: 1
Engineering, 04.07.2019 18:10
Afour cylinder four-stroke in-line engine has a stroke of 160mm, connecting rod length of 150mm, a reciprocating mass of 3kg and its firing order is 1-3-4-2. the spacing between cylinders is 100mm. i. show that the engine is in balance with regard to the primary inertia forces and primary 3. a and secondary inertia couples. li determine the out of balance secondary inertia force ii. propose ways of balancing this out of balance force and discuss the challenges that will arise
Answers: 3
Consider a drug-eluting balloon catheter deployed into a blood vessel. The balloon is inflated to pe...
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