Probs in Med

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BMED%2210%Conservation%Principals%in%Biomedical%Engineering% Name:%_______________________________%
Spring%2013,%Quiz%4%%%%
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Instructor:%Botchwey%
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1.% To%generate%the%biodegradable%polymer,%poly%(lacticLcoLglycolic%acid)%(PLGA),%a%continuous%production% method% is% used% including% an% aluminum% isopropoxide% catalyst.% % Since% the% catalyst% is% potentially% toxic% to% human% cells,% it% needs% to% be% rinsed% from% the% polymer% solution.% After% processing,% the% polymer% stream% is% washed%into% a%single%wash%unit% with%the%solvent%methylene%chloride.%% Assume%the%unprocessed%polymer% solution%contains% 40.0%wt%%polymer,%10.0%wt%%catalyst,%and% 50.0%wt%%solvent.%Assume%also%that% 80%%of% the% catalyst% fed% to% the% unit% leaves% in% the% waste% solution% (which% contains% only% solvent% and% catalyst),% and% that% the% catalyst% concentration% in% the% waste% solution% is% the% same% as% the% catalyst% concentration% in% the% product%stream.%The%unit%is%operated%such%that%the%output%stream%has%65.0%wt%%polymer.% %

A. Draw%the%system%used%in%the%purification%of%PLGA.%
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B. Write% a%mass%conservation%equation%for%each%of%the%three%constituents%(solvent,%catalyst,%polymer)% in%the%system.%
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C. Determine%mass%flow%rates%and%weight%percent%of%the%three%constituents%in%each%stream.% %
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2.#Based#on#your#answer#in#question#1,#design#a#new#system#involving#2#wash#units#placed#in#sequence#to# further# reduce# the# mass# of# catalyst# in# the# recovered# polymer# stream.# The# system# should# operate# such# that#there#is#a#reduction#of#an#order#of#magnitude#(factor#of# 20)#in#the#wt%#of#catalyst# in#the#recovered# polymer#stream#after#processing#by#the#second#wash#unit.#Assume#the#product#stream#leaving#wash#unit# 2#has#90.0#wt%#polymer.##

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A. What#is#the#catalyst#weight#percent#in#the#final#outlet#polymer#product#stream?## #
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B. Does#the#design# the# achieve#the#order#of#magnitude#production#of#the#catalyst#weight#percent#in# the#polymer#stream?#
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3.# The# following# figure# labels# each# of# the# components# and# streams# in# a# process# to# separate# living# cells# from# dead# cells# by# centrifugation# in# water# (superscript# a# for# live# cells# and# d# for# dead# cells# and# w# for# water).##

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Assume#that# the#values#of#the#mass#fractions,#!! , !! , !! , !! ,!as#well#as#F,#are#known#and#all#the#units#are# in#mass.#
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A. Determine#the#number#of#net#unknowns#that#exist#in#this#system.# #
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B. Determine#the#number#of#independent#equations.#
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C. How#many#degrees#of#freedom#remain#that#can#be#specified#for#the#process# #
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4.# A# bioreactor# is# a# vessel# in# which# biological# reactions# are# carried# out# involving# enzymes,# microorganisms,#and#or#animal#and#plant#cells.#In#the#anaerobic#(in#the#absence#of#oxygen)#fermentation# of#grain,#the#yeast#Saccharomyces#cerevisae#digests#glucose#(C6H12O6)#from#plants#to#form#the#products# ethanol#(C2H5OH)#and#propenoic#(C2H3CO2H)#by#the#following#overall#reactions:# #

Reaction#1:#C6H12O6#Q>#2C2H5OH#+#2CO2#
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Reaction#2:#C6H12O6#Q>#2C2H3CO2H#+#2H2O#
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Use$the$extent$of$reaction$method# in#the#sections#below# to#determine#the#weight#%#(mass)#of#ethanol# and#propenoic#acid#in#the#product#at#the#end#of#the#process.#Assume#none#of#the#glucose#is#retained#by#the# microorganisms.#

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A. The# bioreactor#tank#is#initially#charged#with#4000#kg#of#a#12%#solution# of#glucose#in#water.#After# fermentation,# 120# kg# of# CO2# is# produced# and# 90# kg# of# unreacted# glucose# remain# in# the# product.# Draw#a#sketch#of#this#process.#

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