Biomedical Engineering Reference
In-Depth Information
sintering at much higher temperature. From the view of material science,
it can be established that the properties of composite material depend not
only on its composition, but also its structure, and the special structure of
the composite material is the key that gives rise to such an excellent perfor-
mance. Excellent species as well as biomaterials have been gradually opti-
mized over millions of years of evolution from one generation to the next,
and gradually have been selected and cured via the biological interaction
among populations and individuals. Therefore, organisms are the most
experienced material designers and skillful experts of materials processing.
The synergy between biominerals and organisms enhances the evolu-
tion and the performance of the mineral itself unfolds through the new
organisms. The intervention of inorganic minerals strengthens some func-
tion of the organisms, which extends the biological diversity of evolution.
Concretely, the mechanical strength of some part of the organ is increasing
so that the organism can survive easily, or the “hard tissue” containing
biominerals can protect the nervous system from damage if the organisms
are under attack. For example, when calcium phosphate became the main
content of bones and teeth, the viability of the species having bones and
teeth was improved, and the functionality of the species was enriched.
The function can be manifested in different ways in later evolution of the
species, and therefore increased in an evolutionary way.
(
a
)
(
a
)
(
b
)
(
b
)
Cribrum
Inside
Areola
Foramen
Figure 13.1
Left: the form and microarchitecture of the silicifi ed valve from the
diatom genus
Coscinodiscus
. (a) Scanning electron micrograph of a silica shell
(Coscinodiscus
sp.). (b) Diagram of the three-dimensional architecture of the
valve. The honeycomb-like chambers are denoted as areolae. The roof on top of
each areola is called a cribrum, which contains a regular pattern of larger pores.
The siliceous Þne structure within each larger pore of a cribrum is denoted as
cribellum. Right: Scanning Electron Microscope (SEM) images of valves from
C.
granii
(a) and
C. asteromphalus
(b) and the interpretation of their patterns by the
phase separation model. (Reprinted with permission from [11])
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