Technology Bulletin 757

WE ARE HERE!!!Sensor-based system improves environmental monitoring

Researchers at Georgia Institute of Technology have developed a system they predict will revolutionize the efficiency and effectiveness of environmental monitoring. Called E-SMART (Environmental Systems Management, Analysis, and Reporting neTwork), the system consists of data management hardware and software and integrated optic chemical sensors. It operates in real time and measures very small amounts of contaminants. In addition, the researchers claim the system will reduce health and safety risks and help ensure environmental compliance. "Right now, the only way technicians have for field analysis is to get out and take samples, bring them back to the lab, and perform wet chemistry tests," says Nile Hartman, a principal research engineer at the Georgia Tech Research Institute. "It's expensive--about $200 a sample, plus the technician time. We have developed a sensor that operates in situ and continuously monitors the site. So you have huge savings in time and cost." At the system's heart are smart sensors that detect a variety of chemical contaminants, including heavy metals, solvents, and petroleum oil and lubricants. The integrated optic interferometric sensors were patented last year by Hartman and the Georgia Tech Research Corp. E-mail [email protected].

WE ARE HERE!!!Tests ensure satellite electronics endure long-term radiation

Fewer failures in satellites used for everything from communications to surveillance may result from bipolar electronics reliability tests developed by Sandia National Laboratories. A Sandia team led by Dan Fleetwood, a physicist in the Radiation Technology and Assurance Department, and colleague Peter Winokur developed the tests to determine how well bipolar electronics--commonly used for analog signal processing in satellites--can survive long-term radiation exposure in space. The challenge was to come up with tests that would predict a 10-year response in a few weeks. "We do this by irradiating components in three ways," Fleetwood explains. "First, we zap them quickly with high doses of radiation at room temperature, taking only a few hours. We compare their response to a second group that receive the same dose of radiation delivered over a few weeks. And we also compare them to a group that receives a high dose of radiation at higher temperatures. By combining the information, we can come up with a simple screening procedure that satellite manufacturers can do themselves to determine the reliability of the parts they put into their systems." ASTM adopted the tests earlier this year as the official test standards for satellite electronic parts. As a result of the tests, one manufacturer reconfigured its system design to avoid potential failures in a critical bipolar voltage regulator. E-mail [email protected].

WE ARE HERE!!!Engineered bacteria inhibits powerplant corrosion

Corrosion costs the U.S. electric power industry between $5 and $10 billion dollars each year. In steam generating plants, for example, half the forced outages are caused by corrosion, increasing the cost of electricity more than 10%. But genetically engineered bacteria could soon change all that, say scientists at EPRI, the science and technology organization for the energy industry. When exposed to most process waters, metal surfaces at the power plant become colonized by microbes. Over time, these colonies merge to form a biofilm. Biofilms are usually damaging: sulfate-reducing bacteria can cause pitting corrosion of most alloys, and even of corrosion-resistant metals. But biofilms can be engineered to have a protective effect, says Barry Syrett, manager of corrosion and science technology at EPRI. Certain aerobic (oxygen-loving) bacteria can cause as much as a 35-fold decrease in the corrosion rate of mild steel, and significant decreases in aluminum and copper corrosion rates, Syrett notes. They do this by consuming the oxygen that would otherwise oxidize the metal. The researchers plan to take a sample of bacteria already thriving in the biofilm at a specific site, give them the genes to manufacture antimicrobials, and reintroduce them to the site. The first site will be a cooled water system on the University of California Irvine campus. E-mail [email protected].

WE ARE HERE!!!Silicon carbide trims power consumption 30%

Improved power electronics devices can save 30% in electric power use in the U.S. over the next 10 years. So reports T. Paul Chow, who directs the Engineering Research Center (ERC) in Power Electronics at Rensselaer Polytechnic Institute, one of five university partners supported by the National Science Foundation in the energy-conservation project. Chow has studied a variety of materials classified as wide band gap because of their electrical properties. He has concluded that silicon carbide has advantages over others that could improve the performance of high-voltage, power-switching devices by at least a factor of 10. Silicon carbide conducts heat better than silicon and requires less material to support the same voltage, according to Chow. It also leaks less at high temperatures, says the researcher. Perhaps of even greater importance, Chow feels, is that, unlike other wide band gap materials, it's possible to grow a thermal oxide on silicon carbide, a necessary step in the manufacture of power devices. For instance, using silicon carbide would let motors and other equipment perform efficiently at much higher temperatures (400C instead of 200C), requiring less cooling and wasting less energy. E-mail [email protected].

WE ARE HERE!!!Sprayer deposits polymer coatings, quickly prototypes parts

Utron Inc. has developed a pulsed sprayer that lays down 100% solid polymer coatings. In addition, the system can be integrated with a CAD system to rapidly prototype polymer components. According to Utron, the pulsed process: deposits functionally gradient polymer layers, finely controls the thickness of each layer, reduces heating and remelting of inner polymers layers, improves adhesion for the quasi-melted viscous powders, and more precisely controls the chemical environment. Since the system operates electrically, it is cleaner and safer than using combustible gases. "Polymer spraying is an attractive option at industries facing environmental regulations, because it is a 100% solid process with zero volatile organic compounds released to the atmosphere," notes F. Douglas Witherspoon, Utron executive vice president. Utron has experimentally demonstrated deposition of 10-mil-thick polyethylene coatings on mild steel under a Small Business Innovation Research contract. A separate contract from the Air Force will investigate functionally graded thermoplastic tubes for solid-rocket motors and liquid-rocket ducting. E-mail [email protected].

WE ARE HERE!!!Resin produces fast, functional prototypes, snap-fits

A sterolithography resin for prototyping snap-fit and functional components claims to have properties similar to polyethylene and polypropylene molding resins. The DuPont Somos 8120 series resin, created for solid-state laser equipment, features fast photo speeds and a broad process latitude. "Somos 8120 offers speed, build tolerance, and part flexibility, while extending laser life by using less power," notes Michelle Wyatt, marketing engineer at DuPont Somos. The resin also offers users the opportunity to create prototypes that resist humidity and water, Wyatt adds. In some cases, the resin can eliminate the need for an RTV mold and cast urethane prototypes. The transparent amber liquid, when exposed to UV light, produces white, translucent parts with properties that approach engineering plastics."Customers can now have parts prototyped where sterolithography would not have previously met their needs," says Wyatt. FAX (302) 328-5693.

WE ARE HERE!!!Optical detector could 'revolutionize' astronomy

Physicists at Stanford University have developed an optical detector so sensitive that it can clock the arrival of a single particle of light and measure its energy with exceptional precision. When applied to light coming from celestial objects, the device's ability to directly measure the location, arrival time, and energy of individual photons could have a revolutionary impact on optical astronomy, say its inventors, Physics Professor Blas Caberea and his research team. Not only can the detector measure all of an individual photon's important attributes, but it can do so throughout the infrared, optical, and ultraviolet portions of the spectrum. The basic sensor, called a superconducting transition edge sensor (TEC), was invented with DOE support as part of a physics experiment patented by Stanford in 1997. It consists of squares of tungsten film that are 20 microns on a side. When the sheets are cooled down to a temperature of 80 thousandths of a degree above absolute zero, the tungsten becomes superconducting. Tungsten's transition between ordinary metal and superconductor is exceptionally sharp, so extremely small changes in the material's temperature give rise to large changes in its electrical properties. E-mail [email protected].

WE ARE HERE!!!Liquid polybutadiene rubber 'pours' into numerous applications

A"breakthrough" technology in liquid polybutadiene rubber, currently available in Europe, has poured its way into North America. The material, known as Krasol(TM), is produced by Czech Republic-based Kaucuk, division of the Unipetrol Group. The material is said to offer these user benefits: can be heated and poured for ease of handling and use, unlike traditional polybutadiene rubber, and has the ability to be mixed with ground rubber, such as tire scrap, for recyclability and cost savings. Applications for the material include: use as a coagent in the cure of rubber by peroxides (wire and cable production), to produce rigid foams, as an electric insulation material, and as noise reduction panels for railroad crossings and other transportation facilities. "Because of their versatility and ease of use, the potential applications for the material are almost limitless," says J. George Drobny, president of Drobny Polymer Associates (Merrimack, NH), the U.S. sales representative for Kaucuk. E-mail [email protected].