Cell phone sensors detect radiation to thwart nuclear terrorism - Sent Using Google Toolbar

Cell phone sensors detect radiation to thwart nuclear terrorism

Cell phone sensors detect radiation to thwart nuclear terrorism

Ephraim Fischbach (on right), Jere Jenkins
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Researchers at Purdue University are working with the state of Indiana to develop a system that would use a network of cell phones to detect and track radiation to help prevent terrorist attacks with radiological "dirty bombs" and nuclear weapons.

Such a system could blanket the nation with millions of cell phones equipped with radiation sensors able to detect even light residues of radioactive material. Because cell phones already contain global positioning locators, the network of phones would serve as a tracking system, said physics professor Ephraim Fischbach. Fischbach is working with Jere Jenkins, director of Purdue's radiation laboratories within the School of Nuclear Engineering.

"It's the ubiquitous nature of cell phones and other portable electronic devices that give this system its power," Fischbach said. "It's meant to be small, cheap and eventually built into laptops, personal digital assistants and cell phones."

The system was developed by Andrew Longman, a consulting instrumentation scientist. Longman developed the software for the system and then worked with Purdue researchers to integrate the software with radiation detectors and cell phones. Cellular data air time was provided by AT&T.

The research has been funded by the Indiana Department of Transportation through the Joint Transportation Research Program and School of Civil Engineering at Purdue.

"The likely targets of a potential terrorist attack would be big cities with concentrated populations, and a system like this would make it very difficult for someone to go undetected with a radiological dirty bomb in such an area," said Longman, who also is Purdue alumnus. "The more people are walking around with cell phones and PDAs, the easier it would be to detect and catch the perpetrator. We are asking the public to push for this."

Tiny solid-state radiation sensors are commercially available. The detection system would require additional circuitry and would not add significant bulk to portable electronic products, Fischbach said.

The technology is unlike any other system, particularly because the software can work with a variety of sensor types, he said.

"Cell phones today also function as Internet computers that can report their locations and data to their towers in real time," Fischbach said. "So this system would use the same process to send an extra signal to a home station. The software can uncover information from this data and evaluate the levels of radiation."

The researchers tested the system in November, demonstrating that it is capable of detecting a weak radiation source 15 feet from the sensors.

"We set up a test source on campus, and people randomly walked around carrying these detectors," Jenkins said. "The test was extremely safe because we used a very weak, sealed radiation source, and we went through all of the necessary approval processes required for radiological safety. This was a source much weaker than you would see with a radiological dirty bomb."

Officials from the Indiana Department of Transportation participated in the test.

"The threat from a radiological dirty bomb is significant, especially in metropolitan areas that have dense populations," said Barry Partridge, director of INDOT's Division of Research and Development.

Long before the sensors would detect significant radiation, the system would send data to a receiving center.

"The sensors don't really perform the detection task individually," Fischbach said. "The collective action of the sensors, combined with the software analysis, detects the source. The system would transmit signals to a data center, and the data center would transmit information to authorities without alerting the person carrying the phone. Say a car is transporting radioactive material for a bomb, and that car is driving down Meridian Street in Indianapolis or Fifth Avenue in New York. As the car passes people, their cell phones individually would send signals to a command center, allowing authorities to track the source."

The signal grows weaker with increasing distance from the source, and the software is able to use the data from many cell phones to pinpoint the location of the radiation source.

"So the system would know that you were getting closer or farther from something hot," Jenkins said. "If I had handled radioactive material and you were sitting near me at a restaurant, this system would be sensitive enough to detect the residue. "

The Purdue Research Foundation owns patents associated with the technology licensed through the Office of Technology Commercialization.

In addition to detecting radiological dirty bombs designed to scatter hazardous radioactive materials over an area, the system also could be used to detect nuclear weapons, which create a nuclear chain reaction that causes a powerful explosion. The system also could be used to detect spills of radioactive materials.

"It's impossible to completely shield a weapon's radioactive material without making the device too heavy to transport," Jenkins said.

The system could be trained to ignore known radiation sources, such as hospitals, and radiation from certain common items, such as bananas, which contain a radioactive isotope of potassium.

"The radiological dirty bomb or a suitcase nuclear weapon is going to give off higher levels of radiation than those background sources," Fischbach said. "The system would be sensitive enough to detect these tiny levels of radiation, but it would be smart enough to discern which sources posed potential threats and which are harmless."

The team is working with Karen White, senior technology manager at the Purdue Research Foundation, to commercialize the system. For more information on licensing the cell phone sensor technology, contact White at (765) 494-2609, kfwhite@prf.org.

Writers:    Emil Venere, (765) 494-4709, venere@purdue.edu

Elizabeth K. Gardner, (765) 494-2081, ekgardner@purdue.edu

Sources:   Ephraim Fischbach, (765) 494-5506, ephraim@physics.purdue.edu

Jere Jenkins, (765) 496-3573, jere@purdue.edu

Andrew Longman, alongman@purdue.edu

Barry Partridge, director, INDOT Division of Research and Development, (765) 463-1521, ext. 251, bpartridge@indot.state.in.us

Andy Dietrick, INDOT Office of Communications, (317) 232-5503, adietrick@indot.in.gov

Purdue News Service: (765) 494-2096; purduenews@purdue.edu


Purdue physics professor Ephraim Fischbach, at right, and nuclear engineer Jere Jenkins review radiation-tracking data as part of research to develop a system that would use a network of cell phones to detect and track radiation. Such a system could help prevent terrorist attacks with radiological "dirty bombs" and nuclear weapons by blanketing the nation with millions of cell phones equipped with radiation sensors able to detect even light residues of radioactive material. Because cell phones already contain global positioning locators, the network of phones would serve as a tracking system. (Purdue News Service photo/David Umberger)

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Organic synthesis - Wikipedia, the free encyclopedia - Sent Using Google Toolbar

Organic synthesis - Wikipedia, the free encyclopedia

Organic synthesis

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Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has developed into one of the most important aspects of organic chemistry. There are two main areas of research fields within the general area of organic synthesis: total synthesis and methodology.



[edit] Total synthesis

Main article: Total synthesis

A total synthesis[1] is the complete chemical synthesis of complex organic molecules from simple, commercially available (petrochemical) or natural precursors. In a linear synthesis there is a series of steps which are performed one after another until the molecule is made- this is often adequate for a simple structure. The chemical compounds made in each step are usually referred to as synthetic intermediates. For more complex molecules, a convergent synthesis is often preferred. This is where several "pieces" (key intermediates) of the final product are synthesized separately, then coupled together, often near the end of the synthesis.

The "father" of modern organic synthesis is regarded as Robert Burns Woodward, who received the 1965 Nobel Prize for Chemistry for several brilliant examples of total synthesis such as his 1954 synthesis of strychnine[2]. Some modern examples include Wender's, Holton's, Nicolaou's and Danishefsky's synthesis of Taxol.

[edit] Methodology

Each step of a synthesis involves a chemical reaction, and reagents and conditions for each of these reactions need to be designed to give a good yield and a pure product, with as little work as possible[3]. A method may already exist in the literature for making one of the early synthetic intermediates, and this method will usually be used rather than "trying to reinvent the wheel". However most intermediates are compounds that have never been made before, and these will normally be made using general methods developed by methodology researchers. To be useful, these methods need to give high yields and to be reliable for a broad range of substrates. Methodology research usually involves three main stages- discovery, optimisation, and studies of scope and limitations. The discovery requires extensive knowledge of and experience with chemical reactivities of appropriate reagents. Optimisation is where one or two starting compounds are tested in the reaction under a wide variety of conditions of temperature, solvent, reaction time, etc., until the optimum conditions for product yield and purity are found. Then the researcher tries to extend the method to a broad range of different starting materials, to find the scope and limitations. Some larger research groups may then perform a total synthesis (see above) to showcase the new methodology and demonstrate its value in a real application.

[edit] Asymmetric synthesis

Main article: Chiral synthesis

Many complex natural products occur as one pure enantiomer. Traditionally, however, a total synthesis could only make a complex molecule as a racemic mixture, i.e., as an equal mixture of both possible enantiomer forms. The racemic mixture might then be separated via chiral resolution.

In the latter half of the twentieth century, chemists began to develop methods of asymmetric catalysis and kinetic resolution whereby reactions could be directed to produce only one enantiomer rather than a racemic mixture. Early examples include Sharpless epoxidation (K. Barry Sharpless) and asymmetric hydrogenation (William S. Knowles and Ryoji Noyori), and these workers went on to share the Nobel Prize in Chemistry in 2001 for their discoveries. Such reactions gave chemists a much wider choice of enantiomerically pure molecules to start from, where previously only natural starting materials could be used. Using techniques pioneered by Robert B. Woodward and new developments in synthetic methodology, chemists became more able to take simple molecules through to more complex molecules without unwanted racemisation, by understanding stereocontrol. This allowed the final target molecule to be synthesised as one pure enantiomer without any resolution being necessary. Such techniques are referred to as asymmetric synthesis.

[edit] Synthesis design

Elias James Corey brought a more formal approach to synthesis design, based on retrosynthetic analysis, for which he won the Nobel Prize for Chemistry in 1990. In this approach, the research is planned backwards from the product, using standard rules[4]. The steps are shown using retrosynthetic arrows (drawn as =>), which in effect means "is made from". Other workers in this area include one of the pioneers of computational chemistry, James B. Hendrickson, who developed a computer program for designing a synthesis based on sequences of generic "half-reactions". Computer-aided methods have recently been reviewed.[5]

[edit] See also

[edit] References

  1. ^ Nicolaou, K. C.; Sorensen, E. J. (1996). Classics in Total Synthesis. New York: VCH. 
  2. ^ Woodward, R. B.; Cava, M. P.; Ollis, W. D.; Hunger, A.; Daeniker, H. U.; Schenker, K. (1954). "The Total Synthesis of Strychnine" (PDF subscription required). Journal of the American Chemical Society 76 (18): 4749–4751. 
  3. ^ March, J.; Smith, D. (2001). Advanced Organic Chemistry, 5th ed. New York: Wiley. 
  4. ^ Corey, E. J.; Cheng, X-M. (1995). The Logic of Chemical Synthesis. New York: Wiley. 
  5. ^ Todd, Matthew H. (2005). "Computer-aided Organic Synthesis" (PDF subscription required). Chemical Society Reviews 34: 247–266. 

[edit] External links