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Alt 05-03-2008, 14:38   #1
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What is the current state of nanoscience And nanotechnology?

What is the current state of nanoscience and
nanotechnology?
Current knowledge in nanoscience comes from developments in
chemistry, physics, life sciences, medicine, and engineering. Nanotechnology is
under active development or already in practical use in several areas:
In materials science, nanoparticles allow for the making of
products with new mechanical properties, including surface friction, wear
resistance, and adhesion.
The smallest components of a computer chip are on a
nanoscale.
The smallest components of a computer chip are on a
nanoscale.
Credit: NanoPrism Technologies, Inc.In biology and medicine, nanomaterials are used to improve
drug design and targeting. Others are being developed for analytical and
instrumental applications.
Consumer products such as cosmetics, sunscreens, fibres,
textiles, dyes, and paints already contain nanoparticles.
In electronic engineering, nanotechnologies are used for
instance to design smaller, faster, and less consuming data storage devices.
Optical devices such as microscopes have also benefited from
nanotechnology.
Current knowledge of science at the nanoscale comes from
developments in disciplines such as chemistry, physics, life sciences, medicine
and engineering. There are several areas in which nanoscale structures are
under active development or already in practical use:
In materials science, nanoparticles allow for the making of
products with mechanical properties very different from those of conventional
materials and can also improve surfaces by adding new friction, wear or
adhesion properties.
In biology and medicine, a greater understanding of the
functioning of molecules and of the origin of diseases on the nanometre scale
has lead to improvements in drug design and targeting. Nanomaterials are also
being developed for analytical and instrumental applications, including tissue
engineering and imaging.
A wide variety of nanoscale materials and coatings are
already in use in consumer products such as cosmetics and sunscreens, fibres
and textiles, dyes, and paints.
The smallest components of a computer chip are on a
nanoscale.
The smallest components of a computer chip are on a
nanoscale.
Credit: NanoPrism Technologies, Inc.The constant drive towards miniaturization in electronic
engineering has led to devices that are well within the nanometre range. Data
storage devices based on nanostructures provide smaller, faster, and lower
consumption systems.
Optical devices have also benefited from this trend and new
types of microscopes have been invented, that can produce images of atomic and
molecular processes at surfaces. More...
3.3 Nanoscience
and Nanotechnology
3.3.1 Introduction Current knowledge
of science at the nanometre scale is derived from many disciplines, originating
with the atomic and molecular concepts in chemistry and physics, and then
incorporating molecular life sciences, medicine and engineering. The
observation and understanding of atomic and molecular behaviour from first
principles was followed by the increasing ability to control and selectively
modify properties of ever smaller pieces of matter in a functional way. Early
examples here are the discoveries in self assembly (Bain et al 1989) which
culminated in current synthetic and supra-molecular chemistry (Lehn 1988, Gomez
–Lopez et al 1996), the increasing knowledge about life’s replication processes
and the co-evolution of physical (Perutz et al 1960, Aue et al 1976, Wuthrich
1995) and chemical methodologies. These have resulted in the portfolio of
current molecular life sciences such as molecular motors and other functional
entities (Mavroidis et al 2004, Clark et al 2004), including biomolecular and
medical engineering and the emerging area of systems biology. On the other
hand, man made micro and nanoscale sensing devices originate from other domains
in microscopy and device engineering but relate to biomedical applications
(Ziegler 2004, Emerich and Thanos 2003).
The deviation of
surface and interface properties from the bulk properties of larger amounts of
materials led to the sometimes unexpected significance of surface effects,
including catalytic activity and wetting behaviour in material composed of
nanosized entities, such as nanoparticles, composites and colloids (Kamat 2002,
Schwerdtfeger 2003). Quantum mechanical principles manifest themselves in the
properties of surfaces of clusters of very small particles, especially those of
the order of 1000 atoms or molecules and less. Composite materials (Komarneni
1992, Schmidt 2000, Hadjipanayis 1999), with increasingly smaller
characteristic sizes of the domains or phases, allowed for the design of
materials with new and optimised physical and / or chemical properties. In
electronic engineering, the miniaturization of devices has progressed well into
the nanometre range with gate oxides in devices being routinely 25 nm thick.
The recently increased public awareness of nanoscience is closely related to
the availability of first real space images of atomic and molecular processes
at surfaces through the invention of Scanning Probe Microscopies (Binnig and
Rohrer 1985).
With the
continuous development of nanotechnology, the possibility for the bottom-up
production of nanoscale materials may result in some kind of self assembly of
structures similar to the self assembly of phospholipid bilayers that resembles
cellular membranes.
On the basis of
current knowledge however, the spontaneous formation of artificial living
systems through self assembly and related processes, suggested by some
prominent commentators, is considered highly improbable. The combination of
self replication with self perpetuation in an engineered nanosystem is
extremely difficult to realize on the basis of current scientific knowledge.
3.3.2 Examples of
Engineered Nanostructures and Materials and Their Applications
There are several
areas of science and technology in which nanoscale structures are under active
development or already in practical use.
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Meric Ofline   Alıntı ile Cevapla
Alt 05-03-2008, 14:39   #2
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In materials
science, nanocomposites with nanoscale dispersed phases and nanocrystalline
materials in which the very fine grain size affords quite different mechanical
properties to conventional microstructures are already in use. In surface
science and surface engineering, nanotopographies offer substantially different
properties related to adhesion, tribology, optics and electronic behaviour.
Supramolecular chemistry and catalysis have led to novel surface and size
dependent chemistry, such as enantioselective catalysis at surfaces. In
biological sciences, fundamental understanding of molecular motors and
molecular functional entities on the nanometre scale has been responsible for
advances in drug design and targeting. Nanoscale functionalised entities and
devices are in development for analytical and instrumental applications in
biology and medicine, including tissue engineering and imaging.
The application
areas in which these advances in nanoscience are making their biggest impact
include electronic, electro-optic and optical devices. The transition from
semiconductor (conventional and organic) technology to nanoscale devices has
anticipated improved properties and resolution, e.g. fluorescence labelling,
scanning probe microscopy and confocal microscopy. Data storage devices based
on nanostructures provide smaller, faster, and lower consumption systems.
In medicine,
greater understanding of the origin of diseases on the nanometre scale is being
derived, and drug delivery through functionalised nanostructures may result in
improved pharmacokinetic and targeting properties.
A wide variety of
functional nanoscale materials and functional nanoscale surfaces are in use in
consumer products, including cosmetics and sunscreens, fibres and textiles,
dyes, fillers, paints, emulsions and colloids.
Source & ©: SCENIHR
The appropriateness of existing methodologies to assess the potential
risks associated with engineered and adventitious products of nanotechnologies
(2006),
3.3 Nanoscience and Nanotechnology, p. 11 3.3.4 Nanoscale
materials properties
Material
properties depend on structure and composition, and can typically be engineered
or modified by changing the relative influence of interfacial or interphase
properties and the macroscopic bulk properties through the characteristic size
or dimension of components and domains. This approach had already emerged
centuries ago with steel alloys and has been so powerful that many engineering
materials today are composites with micro to nanoscale domain sizes. Depending
on the physical or chemical character of each domain, there is a complex
interrelation between the structure and the composition of the material, which
may relate to the bulk and surface properties of each ingredient and newly
emerging properties localized at the interface. selective chemical reactivity
is quite common with nanocomposites, which gives the potential for
disintegration of the material into one or the other component. Complex
processes govern this behaviour, which clearly relates to nanoparticle release
into the environment.
3.3.5 Conclusions. The exploitation
of the properties associated with the nanoscale is based on a small number of
discrete differences between features of the nanoscale and those of more
conventional sizes, namely the markedly increased surface area of nanoparticles
compared to larger particles of the same volume or mass, and also quantum
effects. Questions naturally arise as to whether these features pose any
inherent threats to humans and the environment. Bearing in mind that naturally
occurring processes, such as volcanoes and fires, in the environment have been
generating nanoparticles and other nanostructures for a very long time, it
would appear that there is no intrinsic risk associated with the nanoscale per
se for the population as a whole. As noted above, there is also no reason to
believe that processes of self assembly, which are scientifically very
important for the generation of nanoscale structures, could lead to
uncontrolled self perpetuation. The real issues facing the assessment of risks
associated with the nanoscale are largely concerned with the increased exposure
levels, of both humans and environmental species, now that engineered
nanostructures are being manufactured and generated in larger and larger
amounts, in the new materials that are being so generated, and the potentially
new routes by which exposure may occur with the current and anticipated
applications.
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Meric Ofline   Alıntı ile Cevapla
Alt 08-03-2008, 13:19   #3
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