Magnetic memory chips, which retain data after the power is turned
off, are becoming available and could eventually supplement or even replace
disk drives in computers. Several research teams are looking to take this
technology beyond simply storing data by using it in computer chips that
Researchers from the University of Notre Dame and the Technical University
of Munich in Germany have taken a step toward magnetic logic chips with
device that carries out the basic binary logic operations necessary for
computing. The device uses nanoscale magnets in a quantum dot cellular
automata architecture that was previously developed at Notre Dame. (See
dot logic advances, TRN, October 11, 2000)
The minuscule oblong magnets are arranged in sets of eight to form
majority gates, which are a type of binary logic gate that uses three
inputs and one output. Combinations of of this type of gate can produce
all of the necessary logic for today's computers.
Magnetic logic uses little power and retains data without power.
Magnetic logic could someday be used to make computers that turn on instantly
without having to boot up and computer chips that can be easily reconfigured.
(Majority Logic Gate for Magnetic Quantum-Dots Cellular Automata,
Science, January 13, 2006)
Seeing the light of Net access
High-speed Internet access and wireless home networks are widespread
technologies, and researchers are working to make them faster and cheaper.
Researchers from the Pennsylvania State University have designed
a network based on a pair of emerging technologies: broadband over powerlines
and optical wireless networks. Broadband over powerlines brings data communications,
including Internet access, over powerlines to every outlet and light fixture
in a home. Optical wireless networks transmit data using lightwaves.
The scheme uses white light-emitting diodes (LEDs) for lighting
and networking. Most research on optical wireless networks calls for infrared
light rather than white light. White light-emitting diodes are emerging
as a low-power, low-cost alternative to incandescent and fluorescent lighting.
The wireless networking techniques developed for infrared also apply to
white light, but the white light sources used for illumination provide
better wireless coverage than infrared systems.
With the right configurations, in-home powerlines and optical
wireless networks could transmit data at 1 gigabit per second. High-speed
Internet connections via cable and telephone lines typically range from
1.5 to 8 megabits per second, and today's radio-based wireless networks
range from 11 to 108 megabits per second.
The scheme could provide a simple, cost-effective way of bringing
high-speed networking to computers, televisions and telephones throughout
homes and offices.
(Broadband Access over Medium and Low Voltage Powerlines and Use
of White Light Emitting Diodes for Indoor Communications, IEEE Consumer
Communications & Networking Conference, Las Vegas, Nevada, January 8-10,
Carbon gets more hydrogen
Hydrogen is a clean-burning fuel, but using it as an environmentally
friendly energy source requires finding clean ways to produce it. One
of the most promising approaches is solar water-splitting, a scheme to
use sunlight to drive the chemical separation of hydrogen and oxygen from
The catalyst is the key to splitting water into oxygen and hydrogen.
Much recent research has focused on titanium dioxide catalysts, and last
year researchers found that nanotubes made of titanium dioxide are more
effective than bulk titanium dioxide. The catch is pure titanium dioxide
only works with ultraviolet light, which makes up only a small portion
of sunlight. (See Nanotubes
crank out hydrogen, TRN, February 9/16, 2005)
Researchers from the University of Texas at Austin have found
a way to add carbon to the titanium dioxide nanotubes in order to shift
their catalytic activity from ultraviolet to visible light. They also
found that the length of the nanotubes plays a key role; 3.3 microns is
The carbon-infused titanium dioxide nanotubes generated more hydrogen
from sunlight than pure titanium dioxide nanotubes.
(Novel Carbon-Doped TiO2 Nanotube Arrays with High Aspect Ratios
for Efficient Solar Water Splitting, Nano Letters, January 11,
Chemistry pumps artificial muscle
Much of the research into artificial muscle involves using electricity
or temperature to change the shape of polymer materials. A major aim of
this research is to use these materials to someday power machines like
Biological muscle, however, is chemically driven, and early attempts
to make chemically driven artificial muscle have yielded tiny, unstable
devices that could not scale up to larger sizes.
Researchers from the University of Sheffield in England, the Council
for the Central Laboratory of the Research Councils (CCLRC) in England,
and the European Synchrotron Radiation Facility (ESRF) in France have
these problems with a block copolymer material that combines two polymers
at the molecular scale.
The researchers' synthetic muscle increases in volume three times
in the presence of a high pH solution and contracts in the presence of
a low pH solution.
The material is a 90-nanogram weakling compared to biological
muscle; it is one million times less powerful than myosin and 10,000 times
weaker than striated muscle. It is also extremely slow, completing a cycle
of expansion and contraction in about 20 minutes.
However, it demonstrates that biological-like artificial muscle
is possible, and there are routes to making the chemically-driven device
much more powerful, according to the researchers. Such muscles could tap
chemical energy directly rather than having to convert it into electricity
or heat, which could eventually make artificial muscle more practical.
(Reciprocating Power Generation in a Chemically Driven Synthetic
Muscle, Nano Letters, January 11, 2006)
Bits and pieces
A bacterial protein controls
the speed of light down to an extremely slow one millimeter per second,
dead bacteria rotated
by laser beams make useful microfluidic pumps, a combination
of nanoscale "near field" light and ordinary "far field" light promises
high-speed interconnects for parallel processing supercomputers.