December 26, 2005/January 2, 2006

DNA patterns

DNA is a versatile molecule with many potential technological applications because it can organize itself into all manner of useful patterns.

Researchers from Duke University and the Korea Research Institute of Standards and Science have expanded on their DNA grids by giving them the ability to organize other molecules. The DNA grids are made from DNA tiles, or combinations of DNA strands that form rigid structures.

The grids can incorporate different types of molecules at specific points, including molecules that could be used to make electronic and optical components. The grids are more than 60 times smaller than a red blood cell and are part of an ongoing project to build computer chips using DNA to assemble components such as carbon nanotubes into logic circuits. The researchers made three types of patterned grids that spelled "D", "N" and "A".

Meanwhile, Ohio State University researchers are using rubber stamps that contain microscopic holes to stretch and organize DNA strands into ordered arrays such as grid patterns and crossed pairs of short strands. Key to the method is the ability to control the size of a DNA strand.

Ordered arrays of DNA could be used to make bigger and cheaper DNA chips. DNA chips are currently used for genetics research and medical diagnosis. DNA grids and ordered arrays could eventually be used to make smaller, faster and cheaper computer chips.

(Finite-Size, Fully Addressable DNA Tile Lattices Formed by Hierarchical Assembly Procedures, Angewandte Chemie International Edition, published online December 23, 2005; Generating Highly Ordered DNA Nano Strand Arrays, Proceedings of the National Academy Of Sciences, December 20, 2005)

Optical circuits simplified

Computer circuits that use light to transmit information would be much faster and would use less power than today's electronic circuitry. There are a host of challenges in making practical optical circuits, however, because light beams interact with each other only weakly.

Getting light beams to affect each other typically requires high-power light sources, long interaction times and special host materials. Researchers from Bar Ilan University and Tel Aviv University in Israel have overcome these problems with an optical circuit design for microscopic light channels, or waveguides, that contain highly reflective regions that force light beams to interfere with each other.

The researchers designed and simulated several types of typical chip components using optical circuits: binary logic gates, an amplitude modulator, and an analog adder/subtracter. These optical components are the building blocks of optical memory chips, switches and analog-digital converters.

Such optical circuits would be about the same size as existing electronic circuits but would transmit information thousands of times faster.

(Nano Photonic and Ultra Fast All-Optical Processing Modules, Optics Express, December 12, 2005)

Nanotech medicine

Nanotechnology has the potential to improve medicine in many areas. A pair of research developments move nanotechnology treatments for cancer and degenerative eye problems closer to reality.

Researchers from Harvard Medical School and the University of Connecticut have developed a cancer treatment that uses nanoparticles to encapsulate light-sensitive molecules. Nanoparticles are bits of matter not much bigger than molecules. When a nanoparticles is absorbed by a cell it releases the encapsulated molecules. Exposure to visible light makes the molecules toxic, killing the cells. The nanoparticles completely eradicated several types of cancer tumors in mice, according to the researchers.

Meanwhile, researchers from the University of Tokyo, Osaka Prefecture University and Santen Pharmaceutical Co., Ltd. in Japan have developed a macular degeneration treatment for the form of the eye disease that is caused by blood vessels growing under the retina.

The nanoscale treatment involves two types molecules -- one type is light-sensitive and the other aggregates into nanoscale clumps. The clumps accumulate on the menu blood vessels; when the clumps are exposed to light they destroy the blood vessels.

(Polymeric Nanoparticle Preparation That Eradicates Tumors; Nanotechnology-Based Photodynamic Therapy for Neovascular Disease Using a Supramolecular Nanocarrier Loaded with a Dendritic Photosensitizer, Nano Letters, December 14, 2005)

Robotic consciousness

Although we are still a long way from artificial minds, researchers from Meiji University in Japan have moved a step in that direction. They have built a pair of robots that harbor rudimentary consciousnesses.

The first robot, which is the size and shape of a small wastebasket, is able to distinguish between a reflection of itself in a mirror and another identical robot, and is able to imitate the other robot. The robot's neural network enables the self-other recognition and imitative behavior.

The second robot is a humanoid head and face that is capable of expressing human emotions. The robot was fed a stream of information from the Internet, and reacted to the information with facial emotions. These emotional reactions identified, for instance, that fresh fish as good and rotting fish as bad.

The work promises to help scientists understand human consciousness and is a step toward giving robots the tools they need to better interact with people.

(Conscious Robot That Distinguishes between Self and Others and Implements Imitation Behavior, 18th International Conference on Industrial and Engineering Applications of Artificial Intelligence and Expert Systems, Bari, Italy, June 22-24, 2005; Expression of Emotion in Robots Using a Flow of Artificial Consciousness, 6th IEEE International Symposium on Computational Intelligence in Robotics and Automation, Espoo, Finland, June 27-30, 2005)

Bits and pieces

An electronic camera reads all of the bits at once in a quantum computer, providing a simple way of reading out data in practical quantum computers; an artificial cell component produces the biological fuel ATP; a nanostructured electrode boosts dye-based solar cell performance to 8 percent, boosting prospects for cheap solar cells; a nanomechanical sensor distinguishes protein shapes; a two-dimensional DNA scaffold assembles several types of nanoscale components into arrays for making nanoscale devices; self-assembling micro-scale cubes trap cells.

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