Biomedical Engineering Reference
In-Depth Information
Further Reading
Kabel, M.A., Bos, G., Zeevalking, J., Voragen, A.G.J., Schols, H.A., 2006. Effect of pretreatment severity on xylan solubility
and enzymatic breakdown of the remaining cellulose from wheat straw. Bioresource Technology, 98, 2034 e 2042.
Liu, S., 2010. Woody biomass: Niche position as a source of sustainable renewable chemicals and energy and
kinetics of hot-water extraction/hydrolysis. J. Biotech. Adv. 28, 563 e 582.
Montan ´ , D., Salvad ´ , J., Farriol, X., Jollez, P., Chornet, E., 1994. Phenomenological kinetics of wood delignification:
application of a time-dependent rate constant and a generalized severity parameter to pulping and correlation of
pulp properties. Wood Science and Technology, 28, 387 e 402.
Overend, R., Chornet, E., 1986. Fractionation of lignocellulosics by steam-aqueous pretreatment. The Philosophical
Transactions of the Royal Society London, 321, 523 e 536.
Vroom, K.E., 1957. The “H” factor: a means of expressing cooking times and temperatures as a single variable. Pulp
Paper Mag. Can. 58(3), 228 e 231.
PROBLEMS
4.1. Our winery has discovered that all of last year's crop now being stored for aging
contained 200 ppm of a chemical that gives it garlic flavor. However, we find that the
concentration of this chemical is 50 ppm 1 year after it was put in storage. Taste tests in
which this chemical was added to good wine shows that it can be detected only if its
concentration is greater than 10 ppm. How long will we have to age this wine before we
can sell it?
4.2. Our winery chemist has just found that the reaction by which the garlic-flavored
compound of the previous problem disappears is by a reaction that produces a tasteless
dimer of the chemical.
(a) With this mechanism, how long must we age our wine before we can sell it?
(b) Since we do not entirely trust his judgment (why would a competent chemist work
for a winery?), we decide to test his results by analyzing the wine after the second
year of aging. What percentages should we find if the reaction is first or second
order?
4.3. The carton of milk in your refrigerator contains 20 cells per glass of a strain of
Escherichia coli which makes people sick. This strain doubles every 2 days, and your
immune system can destroy up to 1000 cells per glass without noticeable effects.
(a) When should the carton of milk be poured down the drain?
(b) At room temperature, this strain doubles every 8 h. For how long is the milk
drinkable if left on the counter?
4.4. Your neighbor just sneezed on your desk, and the drop contains 200 virus particles.
Half of the virus particles are destroyed every 10 min by air oxidation. Can the person
who sits at your desk next hour catch his cold?
4.5. Yogurt is produced by adding a small amount of finished yogurt to fresh milk in
a process whose kinetics can be described approximately as
A ! 2A; r ¼ kC A
It is found that with a certain culture, the concentration of product in fresh milk doubles
in 8 h. If the process is started by adding 5% of finished yogurt to milk, how long is
required to prepare a batch of yogurt?
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