2.2 Mixtures, Solutions, Colloids, Sols, and Gels
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Multiple colloids, with more than two kinds of particles dispersed in a background material, also are evident, such as oil-water-air in porous rock.
When two metals are mixed homogeneously, the combination is called an
‘amalgamation’. Dental ‘amalgam’ is an amalgamation of mercury, a liquid at room
temperature, with silver, a solid at room temperature. The result is a liquid. Mercury
readily forms amalgams with copper, silver, gold and even with neutral ammonium
NH 4 , which acts like a metal in the amalgam.
If the structure of one substance in another exists at a ‘lower dimension’
(filaments or surfaces), then the material is a matrix. If the matrix consists of long
thin threads, the material is fibrous. If the fibers are, to some degree, aligned, the
matrix is ‘ordered’.
2.2.1 Mixtures in Biological Structures
Live systems on Earth use mixtures of carbon-based compounds in salty water to
generate the complexity and activity need for the tasks of sustaining life.
The material structure elements of biological systems must be able to keep
individual life forms localized within the organism, and be stable enough to maintain
the individual life form for a certain replacement lifetime. Additionally, repair
mechanisms and the ability to respond to a variety of environmental pressures are
distinct advantages.
The simplest of life-forms, viral particles, preserve and safeguard their structure
through intermolecular forces within their protein capsid. The much larger and
far more sophisticated cell structures became successful by the fact that important
water-based metabolic processes can be achieved through the highly sophisticated
and ordered mixtures of substances contained in porous cells.
Biologic cells maintain intracellular structural stability by using microtubules, a
polymer of two globular proteins, and by using microfilaments, a linear polymer of
the protein actin. Cellular cytoplasm shows both a sol and a gel behavior by how
the microfilaments make viscoelastic gel-sol transitions. Amoebae pseudopodia use
a sol-gel transformation and contractile microfilaments to ambulate. A cell nucleus,
having embedded macromolecular coils of DNA is a colloid.
In addition, plant cells maintain shape using cellulose, a long chain of sugar
molecules. Wood is produced as cellulose bound in a complex polymer of crosslinked phenols called lignin.
Extracellular auxiliary structures are sometimes created by multicellular life
forms to gain quasi-rigidity. These structures can then hold specialized cells in place
relative to other specialized cells, or relative to gravity. Among the components
in exoskeletons are secretions with proteins and calcium carbonate in the case of
mollusks, and chitin (an N-acetylglucosamine polymer) in the case of insects.
Collagen is an extracellular structural protein, often in the form of elongated
fibrils, affording some rigidity. Collagen consists of long chains of a triple helix
19
Multiple colloids, with more than two kinds of particles dispersed in a background material, also are evident, such as oil-water-air in porous rock.
When two metals are mixed homogeneously, the combination is called an
‘amalgamation’. Dental ‘amalgam’ is an amalgamation of mercury, a liquid at room
temperature, with silver, a solid at room temperature. The result is a liquid. Mercury
readily forms amalgams with copper, silver, gold and even with neutral ammonium
NH 4 , which acts like a metal in the amalgam.
If the structure of one substance in another exists at a ‘lower dimension’
(filaments or surfaces), then the material is a matrix. If the matrix consists of long
thin threads, the material is fibrous. If the fibers are, to some degree, aligned, the
matrix is ‘ordered’.
2.2.1 Mixtures in Biological Structures
Live systems on Earth use mixtures of carbon-based compounds in salty water to
generate the complexity and activity need for the tasks of sustaining life.
The material structure elements of biological systems must be able to keep
individual life forms localized within the organism, and be stable enough to maintain
the individual life form for a certain replacement lifetime. Additionally, repair
mechanisms and the ability to respond to a variety of environmental pressures are
distinct advantages.
The simplest of life-forms, viral particles, preserve and safeguard their structure
through intermolecular forces within their protein capsid. The much larger and
far more sophisticated cell structures became successful by the fact that important
water-based metabolic processes can be achieved through the highly sophisticated
and ordered mixtures of substances contained in porous cells.
Biologic cells maintain intracellular structural stability by using microtubules, a
polymer of two globular proteins, and by using microfilaments, a linear polymer of
the protein actin. Cellular cytoplasm shows both a sol and a gel behavior by how
the microfilaments make viscoelastic gel-sol transitions. Amoebae pseudopodia use
a sol-gel transformation and contractile microfilaments to ambulate. A cell nucleus,
having embedded macromolecular coils of DNA is a colloid.
In addition, plant cells maintain shape using cellulose, a long chain of sugar
molecules. Wood is produced as cellulose bound in a complex polymer of crosslinked phenols called lignin.
Extracellular auxiliary structures are sometimes created by multicellular life
forms to gain quasi-rigidity. These structures can then hold specialized cells in place
relative to other specialized cells, or relative to gravity. Among the components
in exoskeletons are secretions with proteins and calcium carbonate in the case of
mollusks, and chitin (an N-acetylglucosamine polymer) in the case of insects.
Collagen is an extracellular structural protein, often in the form of elongated
fibrils, affording some rigidity. Collagen consists of long chains of a triple helix