Basic HTML Version
25
F
MM
=
F
MMM
+
F
MMG
F
GG
=
F
GGM
+
F
GGG
F
MG
=
F
MGM
+
F
MGG
Moreover, for long chains the following applies:
F
GGM
= F
MGG
(end and beginning of a G-block)
F
MMG
= F
GMM
(end and beginning of a M-block)
Blocks
are exactly what the name implies, namely consecutive sequences of:
..GGGGGGGGG.. (G-blocks)
..MMMMMMM.. (M-blocks)
..MGMGMGMGMGM... (MG- or alternating blocks).
Because of their ability to selectively bind Ca
++
ions, G-blocks are particularly
valuable and important. The average length of G-block (N
G>1
) correlates well
to the strength of Ca-alginate gels, and is particularly important. It is defined
by:
ž
N
G
>
1
=
n
G
−
n
MGM
n
GGM
=
F
G
−
F
MGM
F
GGM
Single G’s (between two M’s) do not qualify for being called a G-block and are
therefore subtracted. All G-blocks are necessarily terminated by the sequence
GGM. Thus the G-block length is the number of G’s (single G’s excluded)
divided by the number of ends, the latter equalling the number of G-blocks.
The somewhat abstract concepts described above tend to become clear after
performing the following exercise: