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214
In this case we have used the formula for
α
= 1/50, 1/100, 1/300 and 1/1000:
It may be noted the W
n
function has a characteristic shape when plotted semi-
logarithmically. And, doesn’t it look a bit like a chromatogram? The fact it does
will be relevant in later chapters (SEC).
The figure above also shows that W
n
has a maximum value which increases
with increasing 1/
α
(decreasing
α
).
Which
α
gives the maximum amount of e.g. a 20-mer? The exact maximum of
W
n
s determined by deriving the equation:
So to obtain a maximum of 20-mer we should degrade to
α
= 2/21. The
corresponding (W
20
)
max
is found by using n = 20 and
α
= 2/21, yielding:
w
20
max
(
)
=
20 0.0952
(
)
2
(1
−
0.0952)
19
=
0.027 (2.7%)
Maximum W
n
when
dW
n
d
α
=
0
⇒
α
=
2
n
+
1