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JAPAN NANONET BULLETIN
-- 7th Issue -- December 11, 2003
Nanotechnology Researchers Network Center of Japan
Ministry of Education, Culture, Sports, Science and Technology (MEXT)
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IN THIS ISSUE
Nanonet Interview:
Tomoji KAWAI, Director/Professor, The Nanoscience and Nanotechnology
Center, The Institute of Scientific and Industrial Research, Osaka
University
Young Researchers' Introduction:
Hitoshi MIYASAKA, Assistant Professor, Department of Chemistry,
Tokyo Metropolitan University and Researcher, Precursory Research for
Embryonic Science and Technology (PRESTO), Japan Science and
Technology Agency (JST)
What's in the next issue?
-- NANO CALENDAR --
For information on nanotechnology related symposiums and conferences
held in the world,
http://www.nanonet.go.jp/english/calendar/
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NANONET INTERVIEW
Creating biological function using nanotechnology
-- "programmed self-organization" technique --
Tomoji KAWAI
Director/Professor, The Nanoscience and Nanotechnology Center, The
Institute of Scientific and Industrial Research, Osaka University
It is now 50 years since Watson and Crick discovered the double helix
structure of the DNA molecule in 1953. During the past 50 years, many
scientists have taken up the challenge of obtaining a direct image of
the detailed nano-structures of DNA molecule without any significant
success. Prof. Kawai developed a method for soft-landing a DNA
molecule on a solid surface, and for the first time in the world, in
1998, he succeeded in acquiring a high resolution image of the double
helix structure of the DNA molecule using a scanning tunneling
microscope (STM). He says he could have succeeded in practically
observing the base sequences of a DNA molecule during that period. "In
order to get into the real world of DNA, it is essential to make an
observation on a nanoscopic scale." His scientific education
encouraged him to experiment, focusing on the intrinsic nature of
things, which in turn has been conducive to the development of a novel
concept.
Prof. Kawai remarks, "nanotechnology is a technology for managing
parts or materials of nanoscopic size. Its importance lies in the fact
that nanoscopic size forms the basis of everything. Good examples are
DNA and protein." Hence, he has thought about the possibility of
developing substances that have high functionality, by assembling
nanoscopic components. The human body is a good example of this kind
of assembly. The human body is regarded as the ultimate product of
nanotechnology, since its biological reactions are all controlled at
the atomic or molecular level, i.e., at the nano-level. This stream of
thought has given rise to a concept called "human-body building" which
aims at realizing various biological functions using artificial
materials. The concept of realizing this is called "programmed self-
organization."
What is the difference between a method that makes the human body
function by assembling nanoscopic parts and the human body's natural
production method? A clue to this resides in the "program." A living
body synthesizes proteins according to the genetic program coded by
genomic DNA which is considered to be a construction plan having a
temporal axis, and is created naturally, by itself, during the course
of interaction with proteins. "When this genetic program starts
working in the mother's uterus, a baby is born in about 10 months. No
technology can match this." Artificial products cannot be made by any
technology without human involvement, while natural products are made
up, literally, "naturally." This difference is largely due to "whether
they are programmed or not." This point of view has played a decisive
role in leading to a new research strategy.
Using this "program" as a keyword, Prof. Kawai initially undertook
research to realize the functions of the five senses in the human body.
A human being receives external signals via his/her eyes, ears, mouth,
nose, hands, and feet. A human being makes contact with the outside
world through these five senses, and thus communicates with society.
"Lack of these senses leaves us as living bodies with no social
connections. The five senses are, therefore, essential." The brain
promptly processes and evaluates the information received by the five
senses, letting hands and mouth respond. Prof. Kawai has undertaken
research to realize these five senses artificially by combining
nanoparts, and to develop a sensor that surpasses the five senses, and
a device equipped with a brain-like function.
For instance, an artificial eye was conceived. Prof. Kawai simulated
information handling processes carried out by a living body using the
concept of programmed self-organization. A light-sensitive material
(organic substance) layered on top, a material for storing the
information (ferroelectric inorganic substance) layered underneath it,
and finally a material for reading out the information (magnetic
substance) were arranged in combination. Its preparation was effected
by a laser molecular beam epitaxy method. In this method, the
molecules (atoms), sputtered from the target materials by a laser
ablation technique, were made multilayered in turn with nano-order
precision using programmed control. Taking the photosensitive retina
in the eye as an example, its thickness is in the order of nanometers.
Therefore, this cannot be achieved without using nanotechnology.
On the other hand, what cannot be sensed by the five senses has
emerged as an easier target to utilize in practical applications.
Snakes and bats respond to infrared rays and ultrasound. It may be
possible for a human being to acquire a superman-like ability if a
sensor that surpasses the five senses can be obtained. Apart from this,
Prof. Kawai believes that the most important field for applying this
technology is in the pursuit of health and safety of the elderly in an
aged society. At the same time, these sensors can be widely applied to
various products such as robots and cars. Prof. Kawai says, "My major
objectives are to realize the five senses of human beings or develop
super five-senses by combining nanoscopic parts elaborately, and to
create an intelligent system by combining such sensors with memory."
"Placing DNA or other molecules on a silicon plate would allow a
circuit to be spontaneously formed. If such a dream becomes a reality,
it would be a revolutionary event," says Prof. Kawai who is aiming to
develop a novel electronic device. He has already succeeded in
developing a method for the formation of a two-dimensional network by
making use of programmed self-organizational ability based on the base
sequences of DNA, and for the controlled arrangement of ultra-fine
particles of gold and magnetic material on a nanoscopic scale.
Additionally, he has also succeeded in the fusion of a semiconductor
device and DNA in forming a DNA network pattern selectively, on a
surface of silicon dioxide film-silicon hydride comprising hydrophilic
-hydrophobic surfaces respectively.
As one of the policy-planning representatives of nanotechnology in
Japan, Prof. Kawai focuses first and foremost on the industrial
applications of nanotechnology. It is his belief that nanotechnology
should be exploited to promote material development, which has already
seen many advances in Japan, since nanotechnology can be applied to
various fields, e.g., electronics, physics, chemistry, biology and the
like. It is capable of fusing different fields, and has an enormous
potential to produce new dream materials, substances, and systems. "In
short, nanotechnology is a highly sophisticated technology because it
is effective not only in strengthening current industries, but also in
creating new ones." For these objectives to be realized, "scientists
who have multidisciplinary vision and the ability to work out a
strategy, as well as thorough knowledge of their own research fields,
must grow more than ever," says Prof. Kawai.
Prof. Kawai has talked about interest in nanotechnology which is
advancing towards human-body building and has urged young scientists
to enter this field. "Although underdeveloped, there are many
interesting research subjects like nanodevices and nanomachines, which
are no longer only dreams. After all, the processes being carried out
in our body everyday come from combinations of structures like
nanodevices and nanomachines."
(Interviewer: Shin Chikushi)
For more information,
http://www.nanonet.go.jp/english/mailmag/2003/007a.html
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YOUNG RESEARCHERS' INTRODUCTION
Controls of structural ordering and magnetism for single-chain magnets
Hitoshi MIYASAKA, Assistant Professor, Department of Chemistry,
Tokyo Metropolitan University and Researcher, Precursory Research
for Embryonic Science and Technology (PRESTO), Japan Science and
Technology Agency (JST)
The origin of bulk magnets lies in the cooperative phenomena of
ordering spins in three dimensions. One-dimensional spin arrangement,
which is magnetically isolated in a three-dimensional sphere, does not
allow the formation of bulk magnets. However, a kind of metastable
magnet known as a single chain magnet (SCM) behaves similarly to
superparamagnets. To design this type of system, three essential
factors must be considered.
First, spin carriers must exhibit a strong uniaxial anisotropy to be
able to block or "freeze" their magnetization in one direction. The
material must also exhibit a spontaneous magnetization to be called a
magnet. Therefore, individual magnetic moments in the chain must not
cancel out in the "frozen" state. Finally, chains must be isolated
magnetically as much as possible to avoid three-dimensional ordering.
Here, the aim of our project is to construct such single chain magnets
based on metal complexes.
Recently, we reported on an SCM of a heterometallic one-dimensional
system of MnIII and NiII ions: [Mn(saltmen)]2[Ni(pao)2(py)2](ClO4)2
(saltmen^2- = N,N'-(1,1,2,2-tetramethylethylene) bis (
salicylideneiminate) and pao^- = pyridine-2-aldoxime). The compound
exhibited a slow relaxation of magnetization obeying the Debye model
with a single relaxation process.
For more information,
http://www.nanonet.go.jp/english/mailmag/2003/007b.html
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WHAT'S IN THE NEXT ISSUE?
Nanonet Interview:
Shunri ODA, Professor, Research Center for Quantum Effect
Electronics, Tokyo Institute of Technology
Young Researchers' Introduction:
Takao MORI, Senior Researcher, Advanced Materials Laboratory,
National Institute for Materials Science and Researcher, Precursory
Research for Embryonic Science and Technology (PRESTO), Japan Science
and Technology Agency (JST)
The next issue of JAPAN NANONET BULLETIN will be delivered on December
25, 2003.
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Nanotechnology Researchers Network Center of Japan distributes
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Nanotechnology Researchers Network Center of Japan
Ministry of Education, Culture, Sports, Science and Technology (MEXT)
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