Electrical Engineering 3BA3: Structure of Biological Materials Day Class Instructor: Dr. I. C. BRUCE Duration of Examination: 3 Hours McMaster University Final Examination December, 2004 This examination paper includes ten (10) pages and fourteen (14) questions. You are responsible for ensuring that your copy of the paper is complete. Bring any discrepancy to the attention of your invigilator. Special Instructions: Use of Casio fx-991 calculator only is allowed. Some equations that may assist you are provided on pages 5 10. Questions 1 8 are multiple-choice questions, each worth 5 pts. Only one answer, a, b, c or d, is correct for each question. Questions 9 14 are short answer and/or mathematical questions, each worth 10 pts. 1. The most important structural substance in vertebrates is: a. collagen, b. keratin, c. proteoglycan, or d. white matter. (5 pts) 2. Silicone has be used as an artificial biomaterial in the manufacture of: a. artificial intraocular lenses, b. artificial heart valves, c. seals for implantable electronic devices, or d. all of the above. (5 pts) 3. Muscle fiber contraction is produced by: a. flexing of the cell membrane, b. the relative movement of actin and myosin filaments within the fiber, c. shrinking of the cell nucleus, or d. none of the above. (5 pts) Continued on page 2
Page 2 of 10 4. Transdermal delivery is suitable for administration of: a. all drugs, b. small-molecule drugs, c. large-molecule drugs, or d. no drugs. (5 pts) 5. In a second-generation enzymatic biosensor, the transducer measures: a. the presence of a product of the chemical reaction catalyzed by the enzyme,, b. the change in the capacitance of the enzyme caused by the chemical reaction, c. the change in the composition of a chemical mediator, or d. any of the above. (5 pts) 6. Filtered backprojection is used in x-ray computed tomography in order to compensate for: a. the use of fan-beam geometry, b. the attenuation of emitted photons as they pass through tissue, c. errors due to Compton scattering, or d. the spatial blurring that occurs from simple backprojection. (5 pts) 7. In the Larmor equation for nuclear magnetic resonance given on page 10, ω o corresponds to the angular frequency at which a proton: a. precesses (wobbles) around the axis of an external magnetic field, b. spins around its own axis, c. flips in response to an RF burst, or d. dephases due to spin-spin interactions. (5 pts) 8. The abbreviation SPECT stands for: a. Sound Pressure Echo Cancellation Technique, b. Scintillating Positron Emission Computed Tomography, c. Single Photon Emission Computed Tomography, or d. Spinning Proton Equilibrium Crossing Time. (5 pts) Continued on page 3
Page 3 of 10 9. Describe the similarities and differences between the tissue engineering of: i. entire organs, and ii. bioartificial organs created using modified xenografts or allografts. (10 pts) 10. Describe the difference between T1-weighted, T2-weighted and proton density-weighted spin echo sequences for MRI image formation, and explain why these different weightings might be used for different medical imaging applications. (10 pts) 11. Describe the function of collimators in x-ray and nuclear medicine imaging. (10 pts) 12. A person with a mass of 70 kg starts out in a standing position and then squats down so that their center of mass (COM) drops by 0.4 meter over a period of 1 second. The vertical position of their COM over the period 0 to 1 second can be described by: () ( π ) dz t = 0.2 cos t 1, () where the vertical position d t is in units of meter and the time t is in units of second. z Calculate the vertical component of the ground reaction force, F ( ) result of this movement. gz t, that would be measured as a (10 pts) 13. Consider the measurement of blood flow velocity in the aorta using the catheter depicted in the figure below. Assume: i. steady, incompressible, inviscid flow in a horizontal direction; ii. a blood density of 1060 kg m 3 ; iii. the pressure measured at the stagnation point (n) is velocity is zero; and iv. the pressure measured at the point (l) is p l = 13332 N m 2 p n = 13417 N m and the blood flow 2 What is the blood flow velocity at point (l), V 1? (10 pts) Continued on page 4
Page 4 of 10 14. Consider an attempt to acquire an ultrasound image of the brain, illustrated in the figure below. Assume: i. an acoustic impedance match between the ultrasound transducer and the skin & soft tissue over the skull; ii. the acoustic impedance of the skin & soft tissue is 1.5 10 6 rayls; iii. the acoustic attenuation of the skin & soft tissue is negligible; iv. the acoustic impedance of skull bone is 7.8 10 6 rayls; v. the acoustic attenuation of skull bone is 26 db/cm; vi. the skull bone is 2-cm thick; and vii. the acoustic impedance of brain tissue is 1.5 10 6 rayls. If the ultrasound intensity produced by the transducer I o = 100 mw/cm 2, what is the ultrasound intensity, I, that is directly transmitted into the brain tissue? (10 pts) THE END Continued on page 5
Supplied Equations Page 5 of 10 Axial stress equations: Axial strain equations: Linear elasticity equation: Ideal rubbery elasticity: Ground reaction force equations: Kinetic energy: Gravitational potential energy: Continued on page 6
Page 6 of 10 Net joint power: Force versus velocity relationship for contracting muscle: Coefficient of restitution for two colliding objects: Energy dissipated in the collision of two objects: Specific gravity of a liquid: Fluid viscosity equation: Fluid drop surface tension balance equation: Bulk modulus (fluid compressibility) equation: Continued on page 7
Page 7 of 10 Speed of sound in a substance: Fluid flow acceleration equation: Fluid flow acceleration along a streamline: Fluid flow acceleration normal to a curving streamline: Hydrostatic equilibrium equation: Hydrostatic pressure difference equation: Conservation of mass for flow within a stream-tube: Continued on page 8
Page 8 of 10 Conservation of mass for flow within a stream-tube of constant volume: Conservation of momentum for flow along a stream-line: Bernoulli equation (conservation of momentum for steady flow along a streamline): Reynold s number criterion for laminar flow: Poiseuille flow velocity profile (laminar viscous flow in a circular tube): Poiseuille flow entry length equation: Inviscid pulse wave propagation in an elastic tube: Continued on page 9
Page 9 of 10 Womersley parameter: Mean kinetic energy of a particle: Fick s law of diffusion: Photon attenuation equation: Radionuclide decay equation: Physical half-life: Acoustic impedance: Pressure reflection coefficient: Continued on page 10
Page 10 of 10 Intensity reflection coefficient: Intensity transmission coefficient: Ultrasound attenuation equation: Doppler frequency equation: Doppler frequency shift: Larmor equation: Spin echo sequence NMR signal strength: END OF SUPPLIED EQUATIONS