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October 21, 2005

Nanoscale technology: Quantum dots produce white light : light bulb replacement

Quantum dots that produce white light could be the light bulb’s successor But chemists at Vanderbilt University discovered a way to make quantum dots spontaneously produce broad-spectrum white light. The report of their discovery, which happened by accident, appears in the communication “White-light Emission from Magic-Sized Cadmium Selenide Nanocrystals” published online October 18 by the Journal of the American Chemical Society.

In the last few years, LEDs (short for light emitting diodes) have begun replacing incandescent and fluorescent lights in a number of niche applications. Although these solid-state lights have been used for decades in consumer electronics, recent technological advances have allowed them to spread into areas like architectural lighting, traffic lights, flashlights and reading lights. Although they are considerably more expensive than ordinary lights, they are capable of producing about twice as much light per watt as incandescent bulbs; they last up to 50,000 hours or 50 times as long as a 60-watt bulb; and, they are very tough and hard to break. Because they are made in a fashion similar to computer chips, the cost of LEDs has been dropping steadily. The Department of Energy has estimated that LED lighting could reduce U.S. energy consumption for lighting by 29 percent by 2025, saving the nation’s households about $125 million in the process.

the new Quantum dot lights are even more efficient than LEDs and produce better light quality and can make lights in different shapes. The light bulb is made out of metal and glass using primarily mechanical processes. Current LEDs are made using semiconductor manufacturing techniques developed in the last 50 years. But, if the quantum dot approach pans out, it could transform lighting production into a primarily chemical process. Such a fundamental change could open up a wide range of new possibilities, such as making almost any object into a light source by coating it with luminescent paint capable of producing light in a rainbow of different shades, including white.

October 20, 2005

Quantitative Cell Biology

This will help put us on the path to computational cell biology as an extension of computational chemistry. Computational chemistry is important to the development of molecular manufacturing.

Yale researchers have reported a method to count the absolute number of individual protein molecules inside a living cell, and to measure accurately where they are located, two basic hurdles for studying biology quantitatively.

"The method makes possible accurate measurements of proteins inside cells using microscopic methods usually used just to show where proteins are located," said senior author Thomas D. Pollard, M.D., Chair and Higgins Professor of Molecular, Cellular & Developmental Biology at Yale, of the work published in Science.

Postdoctoral fellow Jian-Qiu Wu attached a tag called yellow fluorescent protein to proteins of interest, allowing these proteins to be detected in live yeast cells with a light microscope. He used seven sample proteins to demonstrate that the brightness of the fluorescence is directly correlated with the amount of that protein in the cell.

With this reference, they could take a stack of pictures through any whole cell that makes a tagged protein, count up all the fluorescent signal, and calculate the number of molecules by comparing with their standardized sample proteins. The assay works whether the molecules are spread out or concentrated in particular parts of the cell, so they could also count the number of molecules in different locations throughout the cell.

October 19, 2005

Secret code to track color printer use: one partial control step for nanofactory


The pages coming out of your color printer may contain hidden
information that could be used to track you down if you ever cross the
U.S. government.
Last year, an article in PC World magazine pointed out that printouts from many color laser printers contained yellow dots scattered across
the page, viewable only with a special kind of flashlight. The article
quoted a senior researcher at Xerox Corp. as saying the dots contain
information useful to law-enforcement authorities, a secret digital
"license tag" for tracking down criminals.

Similar embedded control and tracking coding seems a likely and probably would be useful for even limited nano-factories. It would require hacking to circumvent and time to detect. It could slow up and deter some forms of abuse. It would be a constant battle to increase the barriers to abuse to those with sophisticated skills.