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  • University team claims single electron transistor breakthrough

    By Steve Bush -- Electronics Weekly, 3/7/2007

    By Steve Bush -- Electronics Weekly, 3/7/2007

    Researchers at the University of Manchester, England, have made a breakthrough in single electron transistor design that they claim will make ultra low power semiconductors a real possibility.

    In an area of semiconductor research dominated by major chip companies in the United States and Japan, the researchers have made a single electron transistor from graphene, which operates at room temperature.

    “This is ideal for modern electronics. It is only nanometers across and it uses as little power as you can imagine,” Dr. Kostya Novoselov told Electronics Weekly. “Only graphene will work at room temperature.”

    Graphene is a single layer of graphite: A one atom thick mesh of carbon atoms resembling chicken wire.

    Carbon atoms inherently make four bonds, but in this hexagonal matrix they can only make three. “The bonds out of the plane are just hanging in the air,” said Novoselov. “They give graphene electrical conductivity.”

    This intrinsic conductivity held back a graphene transistor made by the same team three years ago. “The electrons are moving very fast and are unfortunately hard to top. The transistor was leaky as we could not close the channel completely.” The single electron design can be shut off completely.

    It consists of a 50-nm diameter circular island of graphine -- a quantum dot -- connected to source and drain by two 10-nm (50 atom) wide causeways. A back gate controls the flow of electrons across the causeways to and from the island.

    “We make it easier or harder for electrons to join or leave with the gate,” said Novoselov. “We can put one to 50 electrons on, and we can really count them. Every single state is absolutely stable and we can always put them on one at a time at room temperature.”

    The potential speed of the device is phenomenal. “Silicon transistors have a mobility of around 1,000cm2/Vs. Graphene is around 20,000.”

    Electronics Weekly is the London-based sister publication of Electronic News, part of the EDN Network.

  • Humans show big differences in DNA among themselves! Scientists have shown that our genetic code varies between individuals far more than was previously thought.

    A UK-led team made a detailed analysis of the DNA found in 270 people and identified vast stretches in their codes to be duplicated or even missing.

    A great many of these variations are in areas of the genome that would not damage our health, Matthew Hurles and colleagues told the journal Nature.

    But others are - and can be shown to play a role in a number of disorders.

    To date, the investigation of the human genome has tended to focus on very small changes in DNA that can have deleterious effects - at the scale of just one or a few bases, or "letters", in the biochemical code that programs cellular activity.

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  • Socialized Lizards!They may be cold-blooded, but some lizards have warm personalities and like to socialise, a new study shows.

    A behavioural study reveals that lizards have different social skills: some are naturally inclined to join large groups while others eschew company altogether. The discovery of reptilian personality types could help ecologists better understand and model animal population dynamics, say the researchers involved.

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  • New substance from water! If you think we know all there is to know about water, think again. Scientists claim they have created a totally new alloy of hydrogen and oxygen molecules by splitting water.

    It takes high-energy X-rays and an extremely high pressure, but the end result is a solid mixture of H2 and 02 that has never been identified before, they say. The discovery could change our understanding of the complex chemistry of water.

    The new alloy is "a highly energetic material", says Wendy Mao at Los Alamos National Laboratory, US, who led the research. "It may help us find a way of storing energy."

    Mao’s team subjected water to a pressure 170,000 times greater than atmospheric pressure at sea level. Then they bombarded it with X-rays, causing the water molecules to split and reform into a previously unknown crystalline solid made of H2 molecules and 02 molecules.

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