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A publication of the Foresight Institute
The "Nanotechnology for the Soldier System Conference," sponsored by the U.S. Army Soldier Systems Command (SSCOM), Army Research Office (ARO), Army Research Laboratory (ARL), and the National Science Foundation (NSF), and organized by Battelle Natick Operations, was held July 7-9, 1998, in Cambridge, MA. In opening the conference, Brig. Gen. Robert Floyd II, commanding general of the U.S. Army Soldier Systems Command, asked the researchers present to focus on how to improve the infantry soldier's warfighting capabilities, performance, and quality of life so that technology will give tomorrow's soldier overmatching superiority to any adversary. Specifically, he asked the attendees to develop a program to define nanotechnology research for the near-term (1-5 years), mid-term (6-19 years), and long term (20-25 years).
If the speakers took the General's mandate seriously, then none of them believe general purpose, programmable assemblers capable of self-replication will become feasible within the next 20-25 years. Except for a few comments from the audience, there was no mention of assemblers as a research goal, nor of the consequences for global security, and for the Army's mission, if mature molecular manufacturing systems become widespread within the next few decades. On the other hand, near- and mid-term applications of nanotechnology (mostly nanostructured materials and simple devices, with applications like lighter and stronger and smarter materials, better detection of chemical and biological agents, filtration and decontamination, etc.) were well-addressed by a number of excellent talks.
To mention only a few of these, Samuel Stupp of the Beckman Institute in Urbana, IL, described new materials made from supramolecular systems that self-assemble from block copolymers, in which different sections of the polymer have very different properties. The prototype is a mushroom-like supramolecular assembly in which the "cap" is hydrophobic and the "stem" is hydrophilic. Contrary to expectation, monlayers of these structures stack up so that the stem of one assembly is always on top of the cap of the assembly beneath it, rather than with the stems opposed and the caps opposed. Thus the film that forms has one hydrophobic and one hydrophilic side, making it applicable to, for example, anti-icing coatings. [For more, see "Recent Progress" in Update 29 and "Media Watch" in Update 33.]
William Goddard of the Beckman Institute at Cal Tech described modeling the properties of nanoscale materials through a three-step approach: using quantum mechanical first priniciples calculations to develop force fields, which are used for molecular dynamics to do atomistic simulations, which are in turn used to simulate the properties of mesoscale materials (several nm in scale). He illustrated the approach modeling the ability of specific molecules to diffuse into dendrimers 4-6 nm in diameter, to guide development of such dendrimers as specific sensors. He also discussed applications to modelling the properties of single wall nanotubes.
Donald Tomalia of the Michigan Molecular Institute gave an overview of using dendrimewr technology to construct nanoscale objects of various shapes and sizes, including those linked to immunoglobulin molecules for application in cheap, hand-held devices for detecting viruses.
Marc Kastner of MIT discussed single electron transistors, and how they are limited to very slow switching speeds when used in conventional computer architectures. His proposed solution is a novel architecture based on quantum dot cellular automata, in which devices are coupled by capacitance rather than by current flow. In considering how such devices could be fabricated, he briefly mentioned electron beam lithography and arranging iron atoms using STM into "quantum corrals" as possible approaches, but focused on using chemistry to make nanocrystals of cadmium and selenium, with a covering layer of organic molecules, made by allowing organic compounds containing Cd and Se to react. Such particles can be made from 1.7 to 15.0 nm in diameter, in precise increments of one atomic layer (about 0.2 nm).
|Foresight Update 34 - Table of Contents|
The Web sites in this column describe progress in, or offer resources for, several of the enabling technologies leading to molecular nanotechnology.
The American Chemical Society Web site has posted an illustrated article from the June 8, 1998, issue of Chemical & Engineering News that reports on a symposium, "Materials for the 21st Century & Beyond," held on April 29 at Hunter College of the City University of New York. The symposium gave a superb bird's eye view of progress in chemistry as an enabling technology for nanotechnology: from Nobel Laureate Jean-Marie Lehn's work with self-assembling supramolecular systems, including his latest work with a macrocyclic "wreath" in which four organic strands are held together by metal ion coordination bonds, to the smallest, recently discovered fullerene, a ball of just 36 carbon atoms. The conference sponsors also maintain a Web site that includes the speakers' abstracts at http://sonhouse.hunter.cuny.edu/conferences/symposium98.html.
One proposed path toward nanotechnology is the design of polymers that fold into useful structures. The working example that we have for this approach is the folding of natural proteins. The Federation of American Societies for Experimental Biology (FASEB) Web site http://www.faseb.org/ has a section on "Breakthroughs in Bioscience" that includes the illustrated essay "Unraveling the Mystery of Protein Folding," written for a general audience, which provides a quick layman's introduction to protein structure. The emphasis is on how mistakes in biological protein folding can lead to disease, but the sections that explain how some proteins need help from "chaperone" proteins to fold correctly, and how misfolded proteins are not amorphous blobs, but rather highly structured molecules, provide clues that it might be possible for nanotechnologists to manipulate polymer folding in multiple ways.
For additional information on protein folding, visit the Web site of the Serrano group at the EMBL lab in Heidelberg, Germany. Their recent success in designing a beta sheet peptide is reported in this issue's "Recent Progress" column. In addition to information about their work on designed alpha helical and beta turn structures, they provide a free online service that predicts the percent helical structure in solution of a peptide sequence submitted by the user.
DARPA's Ultra Electronics program "offers a platform for advanced microelectronics research in support of nanoelectronic technologies." The Web site for the program provides a wealth of brief technical reports on past accomplishments (http://web-ext2.darpa.mil/eto/ultra/Weeklies.htm) and current research programs (http://web-ext2.darpa.mil/eto/ultra/98Overview/index.html).
The company Web site of Scanning Technology offers for sale a personal scanning tunneling microscope for about $5000, "based on leading-edge technology in the simplification of Scanning Probe Microscopes." The site also includes an overview of the basic principles of the STM http://members.aol.com/ntinc/basics.html.
Computational chemistry forms the framework for computational nanotechnology. This site lists links for five Electronic Computational Chemistry Conferences (ECCC) that have been held since 1994, with the fifth one to be held this November. These Conferences are held over the Internet and there are no registration fees. Links to the archives of ECCC-2, -3, and -4, and to detailed information on participating in the upcoming ECCC-5:
The above links also provide information about where to get the various plugins needed to view the animations, virtual reality, and other "hyperactive molecule" features used in some of the conference papers.
The Edinburgh Engineering Virtual Library (EEVL) advertises itself as "The UK gateway to quality engineering information on the Internet." Included are searchable databases covering "Reviews of 3,400 quality engineering Web sites" and "Over 100 engineering e-journal Web sites."
Those who like to explore what is known looking for unexpected connections might want to play with a tool made available on the Web to help in making such connections. As explained on the ARROWSMITH Web site:
"ARROWSMITH is an interactive software package that extends the power of a MEDLINE search. It operates on the output of a conventional search in a way that helps the user see new relationships and form and assess novel scientific hypotheses. It is based on the premise that information developed in one area of research can be of value in another without anyone being aware of the fact.
ARROWSMITH is intended primarily for those who already conduct extensive searching in large biomedical bibliographic databases such as MEDLINE, BIOSIS, EMBASE, OR SCISEARCH, and who are interested in discovering novel cross-specialty connections. Whereas conventional searches find only information that is explicitly stated, ARROWSMITH can help users to perceive implicit relationships and connections that may never have been made explicit in published form." u
From Foresight Update 34, originally published 30 August 1998.