Tech & Science
Technology and Science news from Boulder, Colorado
CU scientists discover a new threat from air pollution
Aug 8th
tied to climate change and human health issues
An international research team led by the University of Colorado Boulder and the University of Helsinki has discovered a surprising new chemical compound in Earth’s atmosphere that reacts with sulfur dioxide to form sulfuric acid, which is known to have significant impacts on climate and health.
The new compound, a type of carbonyl oxide, is formed from the reaction of ozone with alkenes, which are a family of hydrocarbons with both natural and man-made sources, said Roy “Lee” Mauldin III, a research associate in CU-Boulder’s atmospheric and oceanic sciences department and lead study author. The study charts a previously unknown chemical pathway for the formation of sulfuric acid, which can result both in increased acid rain and cloud formation as well as negative respiratory effects on humans.
“We have discovered a new and important, atmospherically relevant oxidant,” said Mauldin. “Sulfuric acid plays an essential role in Earth’s atmosphere, from the ecological impacts of acid precipitation to the formation of new aerosol particles, which have significant climatic and health effects. Our findings demonstrate a newly observed connection between the biosphere and atmospheric chemistry.”
A paper on the subject is being published in the Aug. 9 issue of Nature.
Typically the formation of sulfuric acid in the atmosphere occurs via the reaction between the hydroxyl radical OH — which consists of a hydrogen atom and an oxygen atom with unpaired electrons that make it highly reactive — and sulfur dioxide, Mauldin said. The trigger for the reactions to produce sulfuric acid is sunlight, which acts as a “match” to ignite the chemical process, he said.
But Mauldin and his colleagues had suspicions that there were other processes at work when they began detecting sulfuric acid at night, particularly in forests in Finland — where much of the research took place — when the sun wasn’t present to catalyze the reaction. “There were a number of instances when we detected sulfuric acid and wondered where it was coming from,” he said.
In the laboratory, Mauldin and his colleagues combined ozone — which is ubiquitous in the atmosphere — with sulfur dioxide and various alkenes in a gas-analyzing instrument known as a mass spectrometer hooked up with a “flow tube” used to add gases. “Suddenly we saw huge amounts of sulfuric acid being formed,” he said.
Because the researchers wanted to be sure the hydroxyl radical OH was not reacting with the sulfur dioxide to make sulfuric acid, they added in an OH “scavenger” compound to remove any traces of it. Later, one of the research team members held up freshly broken tree branches to the flow tube, exposing hydrocarbons known as isoprene and alpha-pinene — types of alkenes commonly found in trees and which are responsible for the fresh pine tree scent.
“It was such a simple little test,” said Mauldin. “But the sulfuric acid levels went through the roof. It was something we knew that nobody had ever seen before.”
Mauldin said the new chemical pathway for sulfuric acid formation is of interest to climate change researchers because the vast majority of sulfur dioxide is produced by fossil fuel combustion at power plants. “With emissions of sulfur dioxide, the precursor of sulfuric acid, expected to rise globally in the future, this new pathway will affect the atmospheric sulfur cycle,” he said.
According to the U.S. Environmental Protection Agency, more than 90 percent of sulfur dioxide emissions are from fossil fuel combustion at power plants and other industrial facilities. Other sulfur sources include volcanoes and even ocean phytoplankton. It has long been known that when sulfur dioxide reacts with OH, it produces sulfuric acid that can form acid rain, shown to be harmful to terrestrial and aquatic life on Earth.
Airborne sulfuric acid particles — which form in a wide variety of sizes — play the main role in the formation of clouds, which can have a cooling effect on the atmosphere, he said. Smaller particles near the planet’s surface have been shown to cause respiratory problems in humans.
Mauldin said the newly discovered oxidant might help explain recent studies that have shown large parts of the southeastern United States might have cooled slightly over the past century. Particulates from sulfuric acid over the forests there may be forming more clouds than normal, cooling the region by reflecting sunlight back to space.
Most of the laboratory experiments for the study were conducted at the Leibniz-Institute for Tropospheric Research in Leipzig, Germany.
Co-authors on the study include Torsten Berndt and Frank Stratmann from the Leibniz-Institute for Tropospheric Research; Mikko Sipilä, Pauli Paasonen, Tuukka Petäjä, Theo Kurtén, Veli-Matti Kerminen and Markku Kulmula from the University of Helsinki in Finland; and Saewung Kim from the National Center for Atmospheric Research in Boulder. Mauldin also is affiliated with NCAR and the University of Helsinki.
The study was funded by the European Commission Sixth Framework program, the Academy of Finland, The Finnish Center of Excellence, the European Research Council, the Kone Foundation, the Väisälä Foundation, the Maj and Tor Nessling Foundation, the Otto Malm Foundation and the U.S. National Science Foundation.
CU research propels “Blade Runner” to Olympics
Jul 11th
Professors Rodger Kram and Alena Grabowski of the integrative physiology department have been involved in several studies analyzing the performance of amputee athletes, including Pistorius, who use blade-like, carbon fiber leg prostheses in track events. In 2007, Pistorius was barred from international competition by officials from the International Association of Athletics Federations, or IAAF, who ruled his Cheetah Flex-Foot leg prostheses conferred him an advantage over other runners.
Barred from competition, then exonerated
The decision was based in large part on a German study commissioned by the IAAF. However, data presented in April 2008 by a team that included Kram and Grabowski to the Court of Arbitration for Sport in Lausanne, Switzerland — an international group set up to settle disputes in sports — showed Pistorius gained no physiological advantage from the Cheetah prostheses over competitors. The team’s evidence and testimony played a key role in overturning the decision, allowing Pistorius to compete in able-bodied events.
“The methodology of the German study that involved measuring Oscar’s oxygen consumption while running was flawed,” said Kram, who has been measuring the oxygen consumption of runners since 1983. “When we had a chance to properly measure Oscar we found that while he is quite economical in oxygen consumption compared to your average Joe, his values are well within what would be expected for a high-caliber athlete.”
At the arbitration hearings in Switzerland, Kram also argued that if a prosthetic device provides a mechanical advantage, it would very likely provide an energetic or physiological advantage. “Since there is no energetic advantage, it infers that the prostheses do not provide a mechanical advantage either,” said Kram.
Another chance
Although Pistorius subsequently failed to make the 2008 Olympic team, he was selected by South Africa’s Olympic Committee last week to run in both the individual 400 meters and a leg of the 4×400 meter relay in the 2012 Olympic Games in London, which begin on July 27. “I was delighted that Oscar was selected,” said Kram. “I was sure he’d be named to the 4×400 meter relay, but being named to the 400-meter individual event was a surprise.”
Since 2008, the research team involving CU-Boulder has continued its studies. In a 2010 study led by Grabowski, researchers used force-measuring treadmills to analyze the biomechanics of unilateral amputees — those with one amputated leg — over a wide range of running speeds. The team found the force produced by the prosthetic, carbon fiber leg was 9 percent less than that of the unaffected leg. “Applying force to the ground is crucial in sprinting events,” said Grabowski.
“We inferred that running-specific prostheses impair force generation and likely limit top sprinting speed,” said Grabowski, who received her doctorate under Kram in 2008 and recently returned to CU-Boulder as a research faculty member after doing postdoctoral work at the Massachusetts Institute of Technology. Other authors on the 2010 paper included Kram, Craig McGowan of the University of Idaho, William McDermott of the Orthopedic Specialty Hospital in Murray, Utah, and Hugh Herr of MIT.
In a 2012 paper by the same group and led by McGowan, the leg stiffness of Paralympic sprinters with both unilateral and bilateral leg amputations was compared to non-amputee sprinters across a range of speeds. The team found leg stiffness remained constant or increased with speed in non-amputees but decreased in sprinting amputees.
“During running, the leg behaves much like a spring, and the stiffness of the leg greatly influences the overall mechanics of the runner,” said Grabowski. “The study indicates that the prosthetic device limits the ability of a sprinter to change their leg stiffness during running.” In the future, she said, researchers may be able to design a prosthetic device with “adaptive stiffness” that would more accurately emulate the mechanics of a biological ankle during sprinting.
Research fueled by veterans needs
Grabowski, whose work is funded by the Veterans Administration, is particularly interested in designing better prosthetic ankle devices for military veterans or those on active duty who have undergone amputations. In collaboration with the Denver Department of Veterans Affairs, Grabowski is beginning a research effort to further develop battery-powered ankle-foot prostheses for walking and running. Such prostheses have the potential to restore mobility to users similar to the mobility they had prior to amputation, she said.
The research team is interested in locating potential test subjects in the Denver-Boulder area with leg amputations to participate in lab studies. “CU-Boulder is actively pursuing research that aims to improve the lives of amputees, particularly veterans and current military personnel,” she said. Potential study candidates can contact Grabowski at Alena.Grabowski@colorado.edu.
Research in Kram’s Locomotion Laboratory on the CU-Boulder campus goes far beyond athletics. Collaborating faculty and students are targeting the energetic costs of walking, including uphill and downhill walking in older adults; the energetics of passive cycling to treat and prevent obesity and heart disease; and studies on animal locomotion, including kangaroos, tortoises and elephants.
For more information on the CU-Boulder Locomotion Laboratory visit http://www.colorado.edu/intphys/research/locomotion.html. For more information on CU’s integrative physiology department visithttp://www.colorado.edu/intphys/.
CU team helps find the “God” particle
Jul 5th
Multinational team searching for answers about dark matter, dark energy, gravity and the fundamental laws of physics.
An international team including University of Colorado Boulder researchers has found the first direct evidence for a new particle that likely is the long sought-after Higgs boson, believed to endow the universe with mass.
Comprised of thousands of scientists, students and support staff working at the European Organization for Nuclear Research, or CERN, the team has been conducting experiments at a facility known as the Large Hadron Collider, a $10 billion, 17-mile underground loop below the Swiss-French border in Geneva that is the world’s most powerful atom smasher. Scientists have been using the LHC to attempt to recreate conditions immediately following the Big Bang by smashing protons together, searching for answers about dark matter, dark energy, gravity and the fundamental laws of physics.
Higgs boson particle thought to give other particles their mass
A huge target of the LHC effort has involved looking for evidence of the elusive Higgs boson, a theoretical elementary particle that has been predicted by physicists. Thought to give other elementary particles their mass, the Higgs boson is the only particle predicted by the Standard Model of particle physics — a scientific theory of how the universe works at the simplest level — that has not been directly detected.
The CERN team is reporting evidence today of an anomalous “bump” in a particular search region of the energy spectrum targeted by the scientists that has a mass of about 125 billion electronic volts, or 125 GeV, said CU-Boulder physics Professor John Cumalat. The research team designed their searches around the theoretical expectations for the decay of the Standard Model Higgs boson particle, he said.
“What we have found is incontrovertible evidence for a new particle at around 125 GeV,” Cumalat said. “To prove it is the Standard Model Higgs particle we will need to carefully measure the new particle’s properties, but with more data these properties can be determined.”
The CU-Boulder high-energy physics team, which includes 15 faculty and students, is involved with the Compact Muon Solenoid, or CMS, one of two massive particle detectors in the LHC and which weighs more than 12,500 tons. The CU team helped design and build the CMS forward pixel detectors — the “eyes” of the device — that help researchers measure the direction and momentum of subatomic particles following collisions, providing clues to their origin and structure.
CU-Boulder Professor William Ford said there were strong hints of the existence of the Higgs boson particle during the CMS particle collisions in 2011. “Now, with the new data looking so similar, it’s hard not to be a believer,” he said. The CERN team hopes to accumulate about four times as much data as they have now on the Higgs boson search project by the end of the year, according to Ford.
“God particle” would being mass and order to the universe
While the Higgs boson was nicknamed “The God Particle” by physicist and Nobel laureate Leon Lederman because its existence would bring mass and order to the universe — a nickname that has been seized on by the media — it is a term physicists do not particularly care for because of its connotations, said Cumalat.
The existence of the Higgs boson theory is crucial to helping to explain the underpinnings of the universe by confirming the Standard Model of physics that explains why fundamental particles — the building blocks of the universe — have mass. Mass is a trait that combines with gravity to give an object weight. Without Higgs boson, there could be no galaxies, stars, planets or people, say researchers.
“It is a very exciting time to be in particle physics and to be involved in an experiment unlocking the meaning of mass,” said CU-Boulder doctoral student Brian Drell.
In addition to Cumalat, Ford and Drell, there are 12 other CU-Boulder people involved in the project: faculty members Uriel Nauenberg, Jim Smith, and Steve Wagner; postdoctoral researchers Alessandro Gaz, Eduardo Luiggi, Keith Ulmer, and Shilei Zang; graduate students Bernadette Heyburn, Andrew Johnson and Troy Mulholland; and technical staff members Eric Erdos and Douglas Johnson.
Sixteen years in the making, the $3.8 billion LHC project involves an estimated 10,000 people and staff from 60 countries, including more than 1,700 scientists, engineers, students and technicians from 94 American universities and laboratories supported by the U.S. Department of Energy’s Office of Science and the National Science Foundation. The United States is providing about $530 million, primarily for the LHC detectors.