Chemists help astronauts make sure their drinking water is clean

Bob Lipert held up a syringe, attached a plastic cartridge and demonstrated how chemistry developed at Iowa State University is helping astronauts and cosmonauts make sure they have safe drinking water at the International Space Station.

Each cartridge contains a thin, one-centimeter disk that's loaded with chemistry, said Lipert, an associate scientist with Iowa State's Institute for Physical Research and Technology and an associate of the U.S. Department of Energy's Ames Laboratory. Run a 10-milliliter water sample through a disk and it will change color in the presence of iodine, which NASA uses to inhibit the growth of microorganisms in the drinking water stored at the space station. The disk will turn from white to yellow and, as it's exposed to higher concentrations of iodine, it will turn to orange and finally to a rust color.

A handheld device -- a diffuse reflectance spectrometer -- can read the disk's color changes and precisely measure the concentration of molecular iodine, or I2. The whole process is called colorimetric solid phase extraction.

Starting in late September, Lipert said astronauts at the space station will use new developments and procedures that convert all forms of iodine in the water samples to molecular iodine. That will give astronauts a more precise reading of total iodine in their drinking water. Lipert said they'll know in real time whether there's too much, too little or just enough iodine in the water.

Disks loaded with different chemistry can also measure and record concentrations of silver, which the Russian Federal Space Agency uses as a biocide in its water supply at the space station. As silver concentrations increase, disks turn from yellow to purple.

Before Iowa State chemists helped develop the new tests, the only way to test the space station's drinking water was to send samples back to earth.

"We figured out the chemistry and put it into a form that can be used in space," Lipert said. "We also took lab techniques and simplified them as much as possible. And we developed procedures that can be used in the absence of gravity."

The result is a quick, accurate test that doesn't use up much drinking water or much astronaut time.

"What's neat about what we came up with is that all the chemistry we need to do can be accomplished in about one minute per sample using a little, 1-centimeter cartridge," Lipert said.

It took some work to develop the test's chemistry and procedures. The NASA-sponsored project began more than a decade ago under the direction of Marc Porter, a former Iowa State professor of chemistry and chemical and biological engineering who is now a USTAR Professor at the University of Utah in Salt Lake City. Lipert has worked on the project since 2000.

Other Iowa State researchers who have worked on the project include Jim Fritz, Distinguished Professor Emeritus of Liberal Arts and Sciences; former post-doctoral researchers Matteo Arena and Neil Dias; and former graduate students April Hill, Daniel Gazda, John Nordling, Lisa Ponton and Cherry Shih. Lorraine Siperko, a research scientist at the University of Utah, has also worked on the project.

The university researchers have also collaborated with the Wyle Integrated Science and Engineering Group, a NASA subcontractor that helped develop and certify the water-testing hardware that has been deployed on the space station.

After a series of successful space tests in 2009 and '10, the researchers' water-testing equipment is now certified operational hardware and is part of the space station's environmental monitoring toolbox.

Lipert said the testing technology can also be a useful tool in many earthbound applications, including forensics tests for drugs, environmental tests for heavy metals and water quality tests for pesticides or herbicides.

"This is a very flexible platform," he said. "You just have to work out the chemistry for each substance you're analyzing."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Iowa State University.

Microwave ovens a key to energy production from wasted heat

 More than 60 percent of the energy produced by cars, machines, and industry around the world is lost as waste heat -- an age-old problem -- but researchers have found a new way to make "thermoelectric" materials for use in technology that could potentially save vast amounts of energy.

And it's based on a device found everywhere from kitchens to dorm rooms: a microwave oven.

Chemists at Oregon State University have discovered that simple microwave energy can be used to make a very promising group of compounds called "skutterudites," and lead to greatly improved methods of capturing wasted heat and turning it into useful electricity.

A tedious, complex and costly process to produce these materials that used to take three or four days can now be done in two minutes.

Most people are aware you're not supposed to put metal foil into a microwave, because it will spark. But powdered metals are different, and OSU scientists are tapping into that basic phenomenon to heat materials to 1,800 degrees in just a few minutes -- on purpose, and with hugely useful results.

These findings, published in Materials Research Bulletin, should speed research and ultimately provide a more commercially-useful, low-cost path to a future of thermoelectric energy.

"This is really quite fascinating," said Mas Subramanian, the Milton Harris Professor of Materials Science at OSU. "It's the first time we've ever used microwave technology to produce this class of materials."

Thermoelectric power generation, researchers say, is a way to produce electricity from waste heat -- something as basic as the hot exhaust from an automobile, or the wasted heat given off by a whirring machine. It's been known of for decades but never really used other than in niche applications, because it's too inefficient, costly and sometimes the materials needed are toxic. NASA has used some expensive and high-tech thermoelectric generators to produce electricity in outer space.

The problem of wasted energy is huge. A car, for instance, wastes about two-thirds of the energy it produces. Factories, machines and power plants discard enormous amounts of energy.

But the potential is also huge. A hybrid automobile that has both gasoline and electric engines, for instance, would be ideal to take advantage of thermoelectric generation to increase its efficiency. Heat that is now being wasted in the exhaust or vented by the radiator could instead be used to help power the car. Factories could become much more energy efficient, electric utilities could recapture energy from heat that's now going up a smokestack. Minor applications might even include a wrist watch operated by body heat.

"To address this, we need materials that are low cost, non-toxic and stable, and highly efficient at converting low-grade waste heat into electricity," Subramanian said. "In material science, that's almost like being a glass and a metal at the same time. It just isn't easy. Because of these obstacles almost nothing has been done commercially in large scale thermoelectric power generation."

Skutterudites have some of the needed properties, researchers say, but historically have been slow and difficult to make. The new findings cut that production time from days to minutes, and should not only speed research on these compounds but ultimately provide a more affordable way to produce them on a mass commercial scale.

OSU researchers have created skutterudites with microwave technology with an indium cobalt antimonite compound, and believe others are possible. They are continuing research, and believe that ultimately a range of different compounds may be needed for different applications of thermoelectric generation.

Collaborators on this study included Krishnendu Biswas, a post-doctoral researcher, and Sean Muir, a doctoral candidate, both in the OSU Department of Chemistry. The work has been supported by both the National Science Foundation and U.S. Department of Energy.

"We were surprised this worked so well," Subramanian said. "Right now large-scale thermoelectric generation of electricity is just a good idea that we couldn't make work. In the future it could be huge."

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by Oregon State University.

Journal Reference:

Krishnendu Biswas, Sean Muir, M. A. Subramanian. Rapid Microwave Synthesis of Indium Filled Skutterudites: An energy efficient route to high performance thermoelectric materials. Materials Research Bulletin, 2011; DOI: 10.1016/j.materresbull.2011.08.058

Nanosensors made from DNA may light path to new cancer tests and drugs

Sensors made from custom DNA molecules could be used to personalize cancer treatments and monitor the quality of stem cells, according to an international team of researchers led by scientists at UC Santa Barbara and the University of Rome Tor Vergata.

The new nanosensors can quickly detect a broad class of proteins called transcription factors, which serve as the master control switches of life. The research is described in an article published in Journal of the American Chemical Society.

"The fate of our cells is controlled by thousands of different proteins, called transcription factors," said Alexis Vallée-Bélisle, a postdoctoral researcher in UCSB's Department of Chemistry and Biochemistry, who led the study. "The role of these proteins is to read the genome and translate it into instructions for the synthesis of the various molecules that compose and control the cell. Transcription factors act a little bit like the 'settings' of our cells, just like the settings on our phones or computers. What our sensors do is read those settings."

When scientists take stem cells and turn them into specialized cells, they do so by changing the levels of a few transcription factors, he explained. This process is called cell reprogramming. "Our sensors monitor transcription factor activities, and could be used to make sure that stem cells have been properly reprogrammed," said Vallée-Bélisle. "They could also be used to determine which transcription factors are activated or repressed in a patient's cancer cells, thus enabling physicians to use the right combination of drugs for each patient."

Andrew Bonham, a postdoctoral scholar at UCSB and co-first author of the study, explained that many labs have invented ways to read transcription factors; however, this team's approach is very quick and convenient. "In most labs, researchers spend hours extracting the proteins from cells before analyzing them," said Bonham. "With the new sensors, we just mash the cells up, put the sensors in, and measure the level of fluorescence of the sample."

This international research effort -- organized by senior authors Kevin Plaxco, professor in UCSB's Department of Chemistry and Biochemistry, and Francesco Ricci, professor at the University of Rome, Tor Vergata -- started when Ricci realized that all of the information necessary to detect transcription factor activities is already encrypted in the human genome, and could be used to build sensors. "Upon activation, these thousands of different transcription factors bind to their own specific target DNA sequence," said Ricci. "We use these sequences as a starting point to build our new nanosensors."

The key breakthrough underlying this new technology came from studies of the natural biosensors inside cells. "All creatures, from bacteria to humans, monitor their environments using 'biomolecular switches' -- shape-changing molecules made from RNA or proteins," said Plaxco. "For example, in our sinuses, there are millions of receptor proteins that detect different odor molecules by switching from an 'off state' to an 'on state.' The beauty of these switches is that they are small enough to operate inside a cell, and specific enough to work in the very complex environments found there."

Inspired by the efficiency of these natural nanosensors, the research group teamed with Norbert Reich, also a professor in UCSB's Department of Chemistry and Biochemistry, to build synthetic switching nanosensors using DNA, rather than proteins or RNA.

Specifically, the team re-engineered three naturally occurring DNA sequences, each recognizing a different transcription factor, into molecular switches that become fluorescent when they bind to their intended targets. Using these nanometer-scale sensors, the researchers could determine transcription factor activity directly in cellular extracts by simply measuring their fluorescence level.

The researchers believe that this strategy will ultimately allow biologists to monitor the activation of thousands of transcription factors, leading to a better understanding of the mechanisms underlying cell division and development. "Alternatively, since these nanosensors work directly in biological samples, we also believe that they could be used to screen and test new drugs that could, for example, inhibit transcription-factor binding activity responsible for the growth of tumor cells," said Plaxco.

This work was funded by the National Institute of Health, the Fond Québécois de la Recherche sur la Nature et les Technologies, the Italian Ministry of University and Research (MIUR) project "Futuro in Ricerca," and the Tri-County Blood Bank Santa Barbara Foundation.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of California - Santa Barbara, via EurekAlert!, a service of AAAS.

Journal Reference:

Alexis Valle´e-Be´lisle, Andrew J. Bonham, Norbert O. Reich, Francesco Ricci, Kevin W. Plaxco. Transcription Factor Beacons for the Quantitative Detection of DNA Binding Activity. Journal of the American Chemical Society, 2011; 133 (35): 13836 DOI: 10.1021/ja204775k

New material shows promise for trapping pollutants

 Water softening techniques are very effective for removing minerals such as calcium and magnesium, which occur as positively-charged ions in "hard" water. But many heavy metals and other inorganic pollutants form negatively-charged ions in water, and existing water treatment processes to remove them are inefficient and expensive.

Chemists at the University of California, Santa Cruz, have now developed a new type of material that can soak up negatively-charged pollutants from water. The new material, which they call SLUG-26, could be used to treat polluted water through an ion exchange process similar to water softening. In a water softener, sodium ions weakly attached to a negatively-charged resin are exchanged for the hard-water minerals, which are held more tightly by the resin. SLUG-26 provides a positively-charged substrate that can exchange a nontoxic negative ion for the negatively-charged pollutants.

"Our goal for the past 12 years has been to make materials that can trap pollutants, and we finally got what we wanted. The data show that the exchange process works," said Scott Oliver, associate professor of chemistry at UC Santa Cruz.

The chemical name for SLUG-26 is copper hydroxide ethanedisulfonate. It has a layered structure of positively-charged two-dimensional sheets with a high capacity for holding onto negative ions. Oliver and UCSC graduate student Honghan Fei described the compound in a paper that will be published in the journal Angewandte Chemie and is currently available online.

The researchers are currently focusing on the use of SLUG-26 to trap the radioactive metal technetium, which is a major concern for long-term disposal of radioactive waste. Technetium is produced in nuclear reactors and has a long half-life of 212,000 years. It forms the negative ion pertechnetate in water and can leach out of solid waste, making groundwater contamination a serious concern.

"It's a problem because of its environmental mobility, so they need new ways to trap it," Oliver said.

In their initial studies, the researchers used manganese, which forms the negative ion permanganate, as a non-radioactive analog for technetium and pertechnetate. The next step will be to work with technetium and see if SLUG-26 performs as effectively as it did in the initial studies.

"Whether or not it can be used in the real world is still to be seen, but so far it looks very promising," Oliver said.

This research was supported by the National Science Foundation.

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by University of California - Santa Cruz. The original article was written by Tim Stephens.

Journal Reference:

Honghan Fei, Scott R. J. Oliver. Copper Hydroxide Ethanedisulfonate: A Cationic Inorganic Layered Material for High-Capacity Anion Exchange. Angewandte Chemie, 2011; DOI: 10.1002/ange.201104200