Study reveals how oxygen is like kryptonite to titanium

UC Berkeley scientists have found the mechanism by which titanium, prized for its high strength-to-weight ratio and natural resistance to corrosion, becomes brittle with just a few extra atoms of oxygen.

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Shown is a cross section of grade 3 titanium (containing 0.3 percent oxygen) that has been put under stress and deformed. The defects in the crystal are evident. Oxygen impurities forced the defects to spread onto different planes of the material. (Image by Qian Yu)

The discovery, described in the Feb. 6 issue of the journal Science, has the potential to open the door to more practical, cost-effective uses of titanium in a broader range of applications. The popular silver-gray metal can already be found in high-end bicycles, laptops and human implants, among other products. But high-grade titanium with low levels of oxygen is hard to come by, and the expense of purifying the metal has prevented its wider use in applications for the construction, automotive and aerospace industries.

“If you could process titanium in a way that retained its optimal properties but at a cost comparable to aluminum, you would find uses in cars, trucks, aircraft and ships,” said study senior author Andrew Minor, an associate professor of materials science and engineering and faculty scientist at Lawrence Berkeley National Laboratory. “The high corrosion resistance and excellent specific properties of titanium are very attractive, and reducing the costs to the level of aluminum would make using the material a no-brainer.”

Minor led a research team from the department of materials science and engineering that focused on solving the long-standing mystery in metallurgy of how oxygen causes such a profound change in the characteristics of metals.

“Oxygen is like poison to titanium,” said Minor. “With more oxygen, the material gets harder and more susceptible to cracks, qualities that are not desirable for structural materials.”

A good structural material will have the right balance of ductility — the ability to bend in response to stress — and strength. Minor noted that glass is strong and hard, but not ductile, which is why that material is not used to build vehicles or bridges.

The light blue lines in this schematic illustrate a moving defect, or dislocation, in titanium. The interaction between the dislocation and an oxygen impurity (red atom) leads to the creation of additional dislocations, shown as dark blue lines. (Image by Liang Qi)

Minor added that while many metals have the potential to become brittle with oxygen, titanium is particularly sensitive to even tiny bits of the element. Grade 3 titanium is only 0.3 percent oxygen, yet it is one-third as tough as grade 1 titanium, which is 0.1 percent oxygen. Understanding how oxygen hardens titanium offers a target for research into control of the process, the study authors said.

The researchers subjected various grades of titanium samples to nanocompression tests and examined the resulting impact using advanced transmission electron microscopy techniques and quantum mechanical predictions of defect structures. They found that the interactions between oxygen and the crystalline defects, known as dislocations, that are characteristic of titanium were key to how the material hardened.

The researchers found that oxygen atoms acted like bumps in the road for the corkscrew-shaped dislocations found in titanium. “The mechanical shuffling that occurs as dislocations pop up and over those atomic bumps creates a domino effect of more dislocations,” said study co-author Daryl Chrzan, a professor of materials science and engineering who led the theoretical effort in the project. With increased oxygen, the titanium becomes more difficult to bend and therefore more susceptible to cracking, the researchers found.

A similar effect is seen by bending a paper clip until it breaks. The more the metal bends, the greater the number of dislocations. Dislocations interfere with the motion of other defects, making the paper clip more difficult to bend. Eventually, the number of dislocations is so high that the paper clip can no longer bend, and instead it breaks.

“Now that we know what it is about the oxygen found in inexpensive titanium that causes the material to harden, we can work on figuring out a way to process it to move oxygen atoms to a place where they don’t cause problems,” said study co-author Mark Asta, a professor of materials science and engineering.

Minor noted that this is already done in the semiconductor industry since oxygen and other impurities are also damaging to silicon-based microprocessors.

Other co-authors of the study included researchers from the Berkeley Lab, Japan’s Nuclear Science and Engineering Directorate and Rolls Royce.

The Office of Naval Research helped support this work. Experiments were performed at the National Center for Electron Microscopy in the Molecular Foundry at Berkeley Lab, which is supported by the U.S. Department of Energy.

Source: UC Berekely

Adults Sought for Study on Aging and Mobility

                                                               Walking stickman
The Biomechanics Laboratory in the kinesiology department is recruiting volunteers for a study about the effects of age and exercise on walking and muscle function. The researchers hope to learn about how changes in muscle function with age are related to the onset of disability.

The lab is looking for individuals who meet the following criteria: ages 55-70 with healthy body weight who participate in fewer than five 30-minute bouts of exercise per week (or less than a total of 150 minutes of planned exercise per week), no history of reconstructive surgery of the legs, no major health issues (heart disease, diabetes, neurological disease), able to walk for 30 minutes and no contraindications to MRI (metal implant, claustrophobia).

The study consists of two visits: a 1-hour visit to an MRI facility in Amherst and one 3-hour visit to the Biomechanics Lab on campus. During the lab visit researchers will collect data on how participants’ joints move as they walk over the ground and on a treadmill. The study will also collect data on the strength of the muscles in participants’ thighs. All procedures are non-invasive.

Source: UMass

Aromatic flavors of haze on Saturn's largest moon, Titan, recreated

In lab experiments NASA scientists matched the spectral signature of an unknown material the Cassini spacecraft detected in Titan's atmosphere at far-infrared wavelengths. The material contains aromatic hydrocarbons that include nitrogen, a subgroup called polycyclic aromatic nitrogen heterocycles. Credit: NASA/Goddard/JPL

NASA scientists have created a new recipe that captures key flavors of the brownish-orange atmosphere around Saturn's largest moon, Titan.

The recipe is used for lab experiments designed to simulate Titan's chemistry. With this approach, the team was able to classify a previously unidentified material discovered by NASA's Cassini spacecraft in the moon's smoggy haze.

"Now we can say that this material has a strong aromatic character, which helps us understand more about the complex mixture of molecules that makes up Titan's haze," said Melissa Trainer, a planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

The material had been detected earlier in data gathered by Cassini's Composite Infrared Spectrometer, an instrument that makes observations at wavelengths in the far infrared region, beyond red light. The spectral signature of the material suggested it was made up of a mixture of molecules.

To investigate that mixture, the researchers turned to the tried-and-true approach of combining gases in a chamber and letting them react. The idea is that if the experiment starts with the right gases and under the right conditions, the reactions in the lab should yield the same products found in Titan's smoggy atmosphere. The process is like being given a slice of cake and trying to figure out the recipe by tasting it. If you can make a cake that tastes like the original slice, then you chose the right ingredients.

The challenge is that the possibilities are almost limitless in this case. Titan's dirty orange color comes from a mixture of hydrocarbons (molecules that contain hydrogen and carbon) and nitrogen-carrying chemicals called nitriles. The family of hydrocarbons already has hundreds of thousands of members, identified from plants and fossil fuels on Earth, and more could exist.

The logical starting point was to begin with the two gases most plentiful in Titan's atmosphere: nitrogen and methane. But these experiments never produced a mixture with a spectral signature to match to the one seen by Cassini; neither have similar experiments conducted by other groups.

Promising results finally came when the researchers added a third gas, essentially tweaking the flavors in the recipe for the first time. The team began with benzene, which has been identified in Titan's atmosphere, followed by a series of closely related chemicals that are likely to be present there. All of these gases belong to the subfamily of hydrocarbons known as aromatics.

The outcome was best results were obtained when the scientists chose an aromatic that contained nitrogen. When team members analyzed those lab products, they detected spectral features that matched up well with the distinctive signature that had been extracted from the Titan data by Carrie Anderson, a Cassini participating scientist at Goddard and a co-author on this study.

"This is the closest anyone has come, to our knowledge, to recreating with lab experiments this particular feature seen in the Cassini data," said Joshua Sebree, the lead author of the study, available online in Icarus. Sebree is a former postdoctoral fellow at Goddard who is now an assistant professor at the University of Northern Iowa in Cedar Falls.

Now that the basic recipe has been demonstrated, future work will concentrate on tweaking the experimental conditions to perfect it.

"Titan's chemical makeup is veritable zoo of complex molecules," said Scott Edgington, Cassini Deputy Project Scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. "With the combination of laboratory experiments and Cassini data, we gain an understanding of just how complex and wondrous this Earth-like moon really is."

Source: NASA/Goddard Space Flight Center

Study may help slow the spread of flu

A false color image of an influenza virus particle, or “virion.” Credit: Centers for Disease Control/Cynthia Goldsmith

An important study conducted in part at the Department of Energy's SLAC National Accelerator Laboratory may lead to new, more effective vaccines and medicines by revealing detailed information about how a flu antibody binds to a wide variety of flu viruses.

The flu virus infects millions of people each year. While for most this results in an unproductive and uncomfortable week or two, the flu also contributes to many deaths in the average flu season. And while vaccines are effective in preventing the flu, they require almost yearly reformulation to keep up with the constantly changing virus.

At SSRL and APS, a team of researchers from The Scripps Research Institute, Fujita Health University and Osaka University studied both samples of flu virus components and an anti-flu antibody. The antibody, called F045-092, was already known to neutralize the flu by connecting to the region of the flu virus that binds to host cells, so it can no longer bind to its target and cause infection.

"There are patches of the virus that are more hypervariable than others," said Peter Lee, a postdoctoral research associate at The Scripps Research Institute and first author of the paper. "But the flu always binds to host cells within the same region, and so that binding site needs to be functionally conserved. That makes it a site of vulnerability."

The team used the X-ray beams at SLAC's Stanford Synchrotron Radiation Lightsource (SSRL) and Argonne National Laboratory's Advanced Photon Source (APS), both DOE Office of Science User Facilities, to view the structure of the antibody bound to one subtype of the flu virus called H3N2. They discovered that the antibody inserts a loop into the binding site of the virus, which would otherwise attach to a receptor in a host cell. Additional experimental data showed that F045-092 binds a wide variety of strains and subtypes, including all H3 avian and human viruses from 1963 to 2011 that were tested.

This understanding of the antibody's structural details and binding modes offers new insight for future structure-based drug discovery and novel avenues for designing future vaccines.
But the only way to achieve those goals is for many groups of scientists to work together, Lee said. "Our lab is very focused on the structure of the virus and antibodies, while there are lots of other labs focused on everything from small protein design to vaccine design," he said. "Hopefully we can use this structural information and join together as one big team to tackle the flu."

Source: SLAC National Accelerator Laboratory

The NASA model provides a 3-D look at L.A.-area quake

JPL scientists modeled the March 28, 2014 magnitude 5.1 quake near Los Angeles based on USGS seismic data. This model image shows how the quake may appear to airborne radar, such as NASA's UAVSAR, which will survey the area soon. Blue shades indicate the greatest surface displacement. Credit: NASA/JPL-Caltech/USGS/Google Earth

On March 28, residents of Greater Los Angeles experienced the largest earthquake to strike the region since 2008. The magnitude 5.1 quake was centered near La Habra in northwestern Orange County about 21 miles (33 kilometers) east-southeast of Los Angeles, and was widely felt throughout Southern California. There have been hundreds of aftershocks, including one of magnitude 4.1.

Scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif., have developed a model of the earthquake, based on the distribution of aftershocks and other seismic information from the U.S. Geological Survey.

A new image based on the model shows what the earthquake may look like through the eyes of an interferometric synthetic aperture radar, such as NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). JPL scientists plan to acquire UAVSAR data from the region of the March 28 quake, possibly as soon as this week, and process the data to validate and improve the results of their model.

The model image is online at: http://www.jpl.nasa.gov/spaceimages/details.php?id=pia18041
The earthquake is believed to be associated with the Puente Hills Thrust fault, a blind thrust fault (meaning it does not break the earth surface) that zigzags from Orange County northwest through downtown Los Angeles. The same fault was responsible for the magnitude 5.9 Whittier Narrows earthquake on Oct. 1, 1987, which caused eight fatalities, injured several hundred and left about $360 million in property damage.

The NASA model is based on a fault estimated to be 5.6 miles (9 kilometers) long, 3.1 miles (5 kilometers) deep and 1.9 miles (3 kilometers) wide. The modeled fault segment dips upward through the ground at a 60-degree angle. The model estimated that in this earthquake, one side of the fault moved at a slanted angle horizontally and vertically 3.9 inches (10 centimeters) relative to the other side. The model also estimated the maximum displacement of Earth's surface from the quake at approximately 0.4 inch (1 centimeter), which is at the threshold of what is detectable with UAVSAR. The region of greatest ground displacement is indicated by the darker blue area located in the right center of the image.

In Nov. 2008, NASA JPL scientists began conducting a series of UAVSAR flights over regions of Northern and Southern California that are actively deforming and are marked by frequent earthquakes. About every six months, the scientists precisely repeat the same flight paths to produce images of ground deformation called interferograms. From these data, 3-D maps are being created for regions of interest, including the San Andreas and other California faults, extending from the Gulf of California in Mexico to Santa Rosa in the northern San Francisco Bay.

UAVSAR, which flies on a NASA C-20A aircraft from NASA's Armstrong Flight Research Center in California, measures ground deformation over large areas to a precision of 0.04 to 0.2 inches (0.1 to 0.5 centimeters).

By comparing the repeat-pass radar observations, scientists hope to measure any crustal deformations that may occur between observations, allowing them to "see" the amount of strain building up on fault lines, and giving them a clearer picture of which faults are active and at what rates they're moving, both before earthquakes and after them. The UAVSAR fault mapping project is designed to substantially improve knowledge of regional earthquake hazards in California. The 3-D UAVSAR data will allow scientists to bring entire faults into focus, allowing them to understand faults not just at their surfaces, but also at depth. When integrated into computer models, the data should give scientists a much clearer picture of California's complex fault systems.

The scientists are estimating the total displacement occurring in each region. As additional observations are collected, they expect to be able to determine how strain is partitioned between individual faults.
The UAVSAR flights serve as a baseline for pre-earthquake activity. As earthquakes occur during the course of this project, the team is measuring the deformation at the time of the earthquakes to determine the distribution of slip on the faults, and then monitoring longer-term motions after the earthquakes to learn more about fault zone properties.

Airborne UAVSAR mapping can allow a rapid response after an earthquake to determine what fault was the source and which parts of the fault slipped during the earthquake. Information about the earthquake source can be used to estimate what areas were most affected by an earthquake's shaking to guide rescue efforts and damage assessment.

The model was developed as part of NASA's QuakeSim project. The JPL-developed QuakeSim is a comprehensive, state-of-the-art software tool for simulating and understanding earthquake fault processes and improving earthquake forecasting. Initiated in 2002, QuakeSim uses NASA remote sensing and other earthquake-related data to simulate and model the behavior of faults in 3-D both individually and as part of complex, interacting systems. This provides long-term histories of fault behavior that can be used for statistical evaluation. QuakeSim also is used to identify regions of increased earthquake probabilities, called hotspots.

NASA's Earthquake Data Enhanced Cyber-Infrastructure for Disaster Evaluation and Response (E-DECIDER) project, which provides tools for earthquake disaster management and response using remote sensing data and NASA earthquake modeling software, published the model results, along with automatically generated deformation models and aftershock forecasts on a La Habra earthquake event page: http://e-decider.org/content/la-habra-earthquake-march-2014

For more information about UAVSAR, visit: http://uavsar.jpl.nasa.gov/

Source: NASA/Jet Propulsion Laboratory

The Vancouver: Nearby Georgia basin may amplify ground shaking from next quake

Multiple scenarios for earthquakes within the Georgia Basin underneath Vancouver indicate that earthquakes would be amplified. Credit: Sheri Molnar and Kim Olsen

Tall buildings, bridges and other long-period structures in Greater Vancouver may experience greater shaking from large (M 6.8 +) earthquakes than previously thought due to the amplification of surface waves passing through the Georgia basin, according to two studies published by the Bulletin of the Seismological Society of America (BSSA). The basin will have the greatest impact on ground motion passing over it from earthquakes generated south and southwest of Vancouver.

"For very stiff soils, current building codes don't include amplification of ground motion," said lead author Sheri Molnar, a researcher at the University of British Columbia. "While the building codes say there should not be any increase or decrease in ground motion, our results show that there could be an average amplification of up to a factor of three or four in Greater Vancouver."

The research provides the first detailed studies of 3D earthquake ground motion for a sedimentary basin in Canada. Since no large crustal earthquakes have occurred in the area since the installation of a local seismic network, these studies offer refined predictions of ground motion from large crustal earthquakes likely to occur.

Southwestern British Columbia is situated above the seismically active Cascadia subduction zone. A complex tectonic region, earthquakes occur in three zones: the thrust fault interface between the Juan de Fuca plate, which is sliding beneath the North America plate; within the over-riding North America plate; and within the subducting Juan de Fuca plate.

Molnar and her colleagues investigate the effect the three dimensional (3D) deep basin beneath Greater Vancouver has on the earthquake-generated waves that pass through it. The Georgia basin is one in a series of basins spanning form California to southern Alaska along the Pacific margin of the North America and is relatively wide and shallow. The basin is filled with sedimentary layers of silts, sands and glacial deposits.

While previous research suggested how approximately 100 meters of material near the surface would affect ground shaking, no studies had looked at the effect of the 3D basin structure on long period seismic waves.

To fill in that gap in knowledge, Molnar and colleagues performed numerical modeling of wave propagation, using various scenarios for both shallow quakes (5 km in depth) within the North America plate and deep quakes (40 -- 55 km in depth) within the Juan de Fuca subducting plate, the latter being the most common type of earthquake. The authors did not focus on earthquakes generated by a megathrust rupture of the Cascadia subduction zone, a scenario studied previously by co-author Kim Olsen of San Diego State University.

For these two studies, the authors modeled 10 scenario earthquakes for the subducting plate and 8 shallow crustal earthquakes within the North America plate, assuming rupture sites based on known seismicity. The computational analyses suggest the basin distorts the seismic radiation pattern -- how the energy moves through the basin -- and produces a larger area of higher ground motions. Steep basin edges excite the seismic waves, amplifying the ground motion.

The largest surface waves generated across Greater Vancouver are associated with earthquakes located approximately 80 km or more, south-southwest of the city, suggest the authors.

"The results were an eye opener," said Molnar. "Because of the 3D basin structure, there's greater hazard since it will amplify ground shaking. Now we have a grasp of how much the basin increases ground shaking for the most likely future large earthquakes."

In Greater Vancouver, there are more than 700 12-story and taller commercial and residential buildings, and large structures -- high-rise buildings, bridges and pipelines -- that are more affected by long period seismic waves, or long wavelength shaking. "That's where these results have impact," said Molnar.

Source: Seismological Society of America

Summary: Tall buildings, bridges and other long-period structures in Greater Vancouver may experience greater shaking from large earthquakes than previously thought due to the amplification of surface waves passing through the Georgia basin, according to two new studies. The basin will have the greatest impact on ground motion passing over it from earthquakes generated south and southwest of Vancouver.

Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion.

This artist’s impression depicts the magma chamber of a supervolcano with partially molten magma at the top. The pressure from the buoyancy is sufficient to initiate cracks in the Earth’s crust in which the magma can penetrate. Credit: ESRF/Nigel Hawtin

Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion. These rare events represent the biggest natural catastrophes on Earth except for the impact of giant meteorites. Using synchrotron X-rays, the scientists established that supervolcano eruptions may occur spontaneously, driven only by magma pressure without the need for an external trigger. The results are published in Nature Geosciences.

The team was led by Wim Malfait and Carmen Sanchez-Valle of ETH Zurich (Switzerland) and comprised scientists from the Paul Scherrer Institute in Villigen (Switzerland), Okayama University (Japan), the Laboratory of Geology of CNRS, Université Lyon 1 and ENS Lyon (France) and the European Synchrotron (ESRF) in Grenoble (France).

A well-known supervolcano eruption occurred 600,000 years ago in Wyoming in the United States, creating a huge crater called a caldera, in the centre of what today is Yellowstone National Park. When the volcano exploded, it ejected more than 1000 km3 of ash and lava into the atmosphere, 100 times more than Mt Pinatubo in the Philippines did in 1992. Big volcanic eruptions have a major impact on the global climate. The Mt Pinatubo eruption decreased the global temperature by 0.4 degrees Celsius for a few months. The predictions for a super volcano are a fall in temperatures by 10 degrees Celsius for 10 years.

According to a 2005 report by the Geological Society of London, "Even science fiction cannot produce a credible mechanism for averting a super-eruption. We can, however, work to better understand the mechanisms involved in super-eruptions, with the goal of being able to predict them ahead of time and provide a warning for society. Preparedness is the key to mitigation of the disastrous effects of a super-eruption."

The mechanisms that trigger supervolcano eruptions have remained elusive to date. The main reason is that the processes inside a supervolcano are different from those in conventional volcanoes like Mt. Pinatubo which are better understood. A supervolcano possesses a much larger magma chamber and it is always located in an area where the heat flow from the interior of Earth to the surface is very high. As a consequence, the magma chamber is very large and hot but also plastic: its shape changes as a function of the pressure when it gradually fills with hot magma. This plasticity allows the pressure to dissipate more efficiently than in a normal volcano whose magma chamber is more rigid. Supervolcanoes therefore do not erupt very often.

So what changes in the lead up to an eruption? Wim Malfait explains: "The driving force is an additional pressure which is caused by the different densities of solid rock and liquid magma. It is comparable to a football filled with air under water, which is forced upwards by the denser water around it." Whether this additional pressure alone could eventually become sufficiently high to crack Earth's crust, leading to a violent eruption, or whether an external energy source like an Earthquake is required has only now been answered.

Whilst it is virtually impossible to drill a hole into the magma chamber of a supervolcano given the depth at which these chambers are buried, one can simulate these extreme conditions in the laboratory. "The synchrotron X-rays at the ESRF can then be used to probe the state -- liquid or solid -- and the change in density when magma crystallises into rock" says Mohamed Mezouar, scientist at the ESRF and member of the team. Jean-Philippe Perrillat from the Laboratory of Geology of CNRS, Université Lyon 1 and ENS Lyon adds: "Temperatures of up to 1700 degrees and pressures of up to 36,000 atmospheres can be reached inside the so-called Paris-Edinburgh press, where speck-sized rock samples are placed between the tips of two tungsten carbide anvils and then heated with a resistive furnace. This special set-up was used to accurately determine the density of the liquid magma over a wide range of pressures and temperatures."

Magma often includes water, which as vapour adds additional pressure. The scientists also determined magma densities as a function of water content.

The results of their measurements showed that the pressure resulting from the differences in density between solid and liquid magma rock is sufficient in itself to crack more than ten kilometres of Earth's crust above the magma chamber. Carmen Sanchez-Valle concludes: "Our research has shown that the pressure is actually large enough for Earth's crust to break. The magma penetrating into the cracks will eventually reach Earth's surface, even in the absence of water or carbon dioxide bubbles in the magma. As it rises to the surface, the magma will expand violently, which is the well known origin of a volcanic explosion."


Source: CNRS

Summary: Scientists have reproduced the conditions inside the magma chamber of a supervolcano to understand what it takes to trigger its explosion. These rare events represent the biggest natural catastrophes on Earth except for the impact of giant meteorites. Using synchrotron X-rays, the scientists established that supervolcano eruptions may occur spontaneously, driven only by magma pressure without the need for an external trigger.