Strain tensor measurements are important for understanding elastic and plastic deformation, but full bulk strain tensor measurement techniques are still lacking, in particular for dynamic loading. Here, such a methodology is reported, combining imaging-based strain field mapping and simultaneous X-ray diffraction for four typical loading modes: one-dimensional strain/stress compression/tension. Strain field mapping resolves two in-plane principal strains, and X-ray diffraction analysis yields volumetric strain, and thus the out-of-plane principal strain. This methodology is validated against direct molecular dynamics simulations on nanocrystalline tantalum. This methodology can be implemented with simultaneous X-ray diffraction and digital image correlation in synchrotron radiation or free-electron laser experiments.

A method for reconstructing the three-dimensional grain structure from data collected with a recently introduced laboratory-based X-ray diffraction contrast tomography system is presented. Diffraction contrast patterns are recorded in Laue-focusing geometry. The diffraction geometry exposes shape information within recorded diffraction spots. In order to yield the three-dimensional crystallographic microstructure, diffraction spots are extracted and fed into a reconstruction scheme. The scheme successively traverses and refines solution space until a reasonable reconstruction is reached. This unique reconstruction approach produces results efficiently and fast for well suited samples.

Silicon nanowire-based sensors find many applications in micro- and nano-electromechanical systems, thanks to their unique characteristics of flexibility and strength that emerge at the nanoscale. This work is the first study of this class of micro- and nano-fabricated silicon-based structures adopting the scanning X-ray diffraction microscopy technique for mapping the in-plane crystalline strain (∊044) and tilt of a device which includes pillars with suspended nanowires on a substrate. It is shown how the micro- and nanostructures of this new type of nanowire system are influenced by critical steps of the fabrication process, such as electron-beam lithography and deep reactive ion etching. X-ray analysis performed on the 044 reflection shows a very low level of lattice strain (<0.00025 Δd/d) but a significant degree of lattice tilt (up to 0.214°). This work imparts new insights into the crystal structure of micro- and nanomaterial-based sensors, and their relationship with critical steps of the fabrication process.

The residual strain distribution has been measured as a function of depth in both top coat and bond coat in as-received and heat-treated air plasma sprayed thermal barrier coating samples. High-energy synchrotron X-ray beams were used in transmission to produce full Debye–Scherrer rings whose non-circular aspect ratio gave the in-plane and out-of-plane strains far more efficiently than the sin2ψ method. The residual strain in the bond coat is found to be tensile and the strain in the β phase of the as-received sample was measured. The residual strains observed in the top coat were generally compressive (increasing towards the interface), with two kinds of nonlinear trend. These was a `jump' feature near the interface, and in some cases there was another `jump' feature near the surface. It is shown how these trend differences can be correlated to cracks in the coating.

Two methods for reconstructing intragranular strain fields are developed for scanning three-dimensional X-ray diffraction (3DXRD). The methods are compared with a third approach where voxels are reconstructed independently of their neighbours [Hayashi, Setoyama & Seno (2017). Mater. Sci. Forum, 905, 157–164]. The 3D strain field of a tin grain, located within a sample of approximately 70 grains, is analysed and compared across reconstruction methods. Implicit assumptions of sub-problem independence, made in the independent voxel reconstruction method, are demonstrated to introduce bias and reduce reconstruction accuracy. It is verified that the two proposed methods remedy these problems by taking the spatial properties of the inverse problem into account. Improvements in reconstruction quality achieved by the two proposed methods are further supported by reconstructions using synthetic diffraction data.

New fitting analyses of two-dimensional diffraction-spot shapes are demonstrated to evaluate strain, strain distribution and domain size in a crystalline ultra-thin film. The evaluations are displayed as residual and population maps as a function of strain or domain size.

The distribution of plastic relaxation defects is studied using a nondestructive sub-micrometre X-ray diffraction scanning technique.

The sin2ψ and cosα methods are compared via diffracting-grain identification from electron backscatter diffraction maps. Artificial textures created by the X-ray diffraction measurements are plotted and X-ray elastic constants of the diffracting-grain sets are computed.

A detailed theoretical and experimental comparison of dark-field electron holography (DFEH) and high-resolution X-ray diffraction (HRXRD) is performed. Both techniques are being applied to measure elastic strain in an array of transistors and the role of the geometric phase is emphasized.

Describing his project of counting bears, bobcats and other predatory mammals along the Appalachian Trail, National Zoological Park wildlife ecologist William McShea looks to American literature for a comparison.

The post Appalachian Trail survey aims hidden cameras at large predators appeared first on Smithsonian Insider.

The Smithsonian Tropical Research Institute in Panama was recently given a collection of more than 25,000 different pollen grains and spores, each mounted on a microscope slide and labeled according to the plant that produced it. “The collection is worldwide in coverage with an emphasis on plants of the Americas,” explains collection donor Alan Graham, professor emeritus at Kent State University and curator at the Missouri Botanical Garden.

The post Research collection of pollen grains given to Smithsonian Tropical Research Institute appeared first on Smithsonian Insider.

Determining the locations of future highways and roads in countries with tropical rainforests will be the greatest single factor in influencing future forest loss, fragmentation and degradation. In broad terms, roads can be thought of as the enemies of rainforests. By spreading people out across the forest, roads inherently promote rapid and widespread deforestation.

The post Roads kill rainforests. Stop them now, say Smithsonian biologists appeared first on Smithsonian Insider.

Recently, scientists at the Smithsonian Tropical Research Institute in Panama discovered that the brain region responsible for learning and memory is larger in the social queens than in the solitary queens of this species. Their study is the first comparison of the brain sizes of social and non-social individuals of the same species.

The post For sweat bees, being social builds a more developed brain appeared first on Smithsonian Insider.

When it comes to brains, is bigger better? Can the tiny brain of a newly hatched spiderling handle problems as adeptly as the brain of a larger adult spider?

The post Tiny, new brains prove just as adept as large, mature brains among tropical orb-web spiders appeared first on Smithsonian Insider.

The Smithsonian’s National Zoo celebrated the completion of Phase I of Elephant Trails, an innovative and expanded home for Asian elephants, on Sept. 2. Phase […]

The post Elephant Trails exhibition opens at National Zoological Park appeared first on Smithsonian Insider.

Water is a critical molecule for human life, and, because it is abundant in space, it also plays an important role in the life of […]

The post Astronomers appraise the amount of water in the Orion Nebula appeared first on Smithsonian Insider.

“Our results support the idea that environmental conditions on tropical non-breeding areas can influence the departure time for spring migration,” said Colin Studds, a postdoctoral fellow at the Smithsonian Conservation Biology Institute's Migratory Bird Center and lead author of the study.

The post Smithsonian scientists find declining rainfall is a major influence for migrating birds appeared first on Smithsonian Insider.

An international team of astronomers has revealed details of a “super-exotic” exoplanet that would make the planet Pandora in the movie Avatar pale in comparison.

The post Astronomers unveil portrait of newly discovered “super-exotic super-Earth” appeared first on Smithsonian Insider.

Five billion years from now, our Milky Way galaxy will collide with the Andromeda galaxy. This will mark a moment of both destruction and creation. The galaxies will lose their separate identities as they merge into one. At the same time, cosmic clouds of gas and dust will smash together, triggering the birth of new stars.

The post The Spitzer Photo Atlas of Galactic “Train Wrecks” appeared first on Smithsonian Insider.

History and geology, not current ecology, are likely what has made tropical forests so variable from site to site.

The post What makes rainforests unique? History, not ecology. appeared first on Smithsonian Insider.

New research on tiny spiders has revealed that their brains are so large that they fill their body cavities and overflow into their legs, say a team of scientists at the Smithsonian Tropical Research Institute in Panama.

The post Brains of tiny spiders fill their body cavities and legs, Smithsonian researchers discover appeared first on Smithsonian Insider.

A newly described species of toothed whale that lived some 3-4 million years ago during the Pliocene, is causing scientists to reconsider what is known about its living cold-water relatives: narwhals and belugas.

The post New fossil whale species raises mystery regarding why narwhals and belugas live only in cold water appeared first on Smithsonian Insider.

A baby boom is underway at the Smithsonian’s National Zoo. Two Guam rail (Gallirallus owstoni) chicks hatched March 3 and 4; they join six others in the Zoo’s collection—three of which live at the Smithsonian Conservation Biology Institute in Front Royal, Va.

The post Extremely rare Guam rails hatch at the Smithsonian’s National Zoo appeared first on Smithsonian Insider.

The snakes are not only eating the area’s birds, but also the birds’ eggs straight from the nest.

The post Invasive pythons in Florida now stealing bird eggs straight from the nest appeared first on Smithsonian Insider.

Their research revealed that the types of waterbirds that inhabit urban estuaries are influenced not only by urban development, but also by a far more natural process―rain.

The post Scientists find that rain may not always be a welcome thing to waterbirds appeared first on Smithsonian Insider.

A new study has unveiled how the tiny hummingbird adapts to flying in heavy rain.

The post Video shows how hummingbirds adjust flight in heavy rain appeared first on Smithsonian Insider.

When it comes to brain size, Homo sapiens generally get the most credit. But to find the baby mammals with the proportionally largest brains on […]

The post Weddell seals have big-brained pups appeared first on Smithsonian Insider.

Hungry rodents that wake up early are much more likely to be eaten than rodents getting plenty of food and shut-eye, according to new results […]

The post Rain forest rodents risk their lives to eat appeared first on Smithsonian Insider.

Chip a tooth and expose a nerve and the result can be a searing sensitivity to hot and cold. The hard outer layer of a […]

The post Scientists map pathway from narwhals’ sensitive tusk to brain appeared first on Smithsonian Insider.

“Early Women in Science” is an online exhibition of 16 women scientists who began their work before 1922. A Biodiversity Heritage Library exhibition, it profiles forward-thinking […]

The post “Early Women in Science” Profiles Trailblazing Women appeared first on Smithsonian Insider.

Pop quiz! Name the first five dinosaurs that come to mind. Chances are good that one you named was Tyrannosaurs rex, a popular favorite perhaps best […]

The post New horse-sized tyrannosaur with big brain reveals how “T. rex” became top predator appeared first on Smithsonian Insider.

The Smithsonian’s National Portrait Gallery celebrates the accomplishments of astronaut and Senator John Glenn (1921-2016) with a watercolor and graphite portrait by Henry C. Caselli […]

The post John Glenn Portrait on View at National Portrait Gallery appeared first on Smithsonian Insider.

With its homely featherless head, undertaker’s charcoal coloring and association with death and decay, the turkey vulture (Cathartes aura) tops few lists as a favorite […]

The post Scientists in awe of huge olfactory bulb found in turkey vulture brain appeared first on Smithsonian Insider.

Javad Fahanik-babaei, Bahareh Rezaee, Maryam Nazari, Nihad Torabi, Reza Saghiri, Remy Sauve, and Afsaneh Eliassi

We have determined the electropharmacological properties of a new potassium channel from brain mitochondrial membrane by planar lipid bilayer method. Our results showed the presence of a channel with a conductance of 150 pS at potentials between 0 and –60 mV in 200 cis/50 trans mM KCl solutions.

The channel was voltage-independent, with an open probability value ~0.6 at different voltages. ATP did not affect current amplitude and Po at positive and negative voltages. Notably, adding iberiotoxin, charybdotoxin, lidocaine, and margatoxin had no effect on the channel behavior. Similarly, no changes were observed by decreasing the cis-pH to 6. Interestingly, the channel was inhibited by adding sodium in a dose dependent manner. Our results also indicated a significant increase in mitochondrial complex IV activity and membrane potential and decrease in complex I activity and mitochondrial ROS production in the presence of sodium ions.

We propose that inhibition of mitochondrial K⁺ transport by Na ions on K⁺ channel opening may be important for cell protection and ATP synthesis.

To understand the long-term effects of a prolonged tropical storm in the Panama Canal watershed, Robert Stallard, staff scientist at the Smithsonian Tropical Research Institute and research hydrologist at the U.S. Geological Survey, and Armando Ubeda, the LightHawk Mesoamerica program manager, organized four flights over the watershed to create a digital map of landslide scars.

The post Smithsonian hydrologist discovers that rainfall has dried up Panama’s drinking water appeared first on Smithsonian Insider.

Under the anomalous transmission condition in the Bragg mode, X-ray interference fringes were observed between two beams with different hyperbolic trajectories in a very weakly bent plane-parallel perfect crystal with negative strain gradient. The origin of the fringes was analysed based on the dynamical theory of diffraction for a distorted crystal. In the reflected beam from the entrance surface, the interference fringes were observed between once- and twice-reflected beams from the back surface. In the transmitted beam from the back surface, the interference fringes were observed between the direct beam and once-reflected beam from the entrance surface. In the emitted beam from the lateral surface, the interference fringes were observed between the beams after different numbers of reflections in the crystal. The multiply reflected beams were formed by a combined result of long propagation length along the beam direction with large divergence of the refracted beams when the strain gradient was negative. The period of these interference fringes was sensitive to very weak strain, of the order of 10−7.

A mysterious nocturnal animal was leaving its tracks on the delicate mirrors of the telescopes at the Smithsonian's Whipple Observatory in Arizona. With a little ingenuity and a live trap, the mystery was solved. The visitor proved to be a ringtail cat, a member of the raccoon family.

The post Astronomers solve mystery of dusty foot trails crossing telescope mirrors appeared first on Smithsonian Insider.

What does it take to care for a pride of lions? Go behind the scenes with Great Cats Curator Craig Saffoe as he works with animal keepers and veterinarians to prepare the National Zoo's frisky lion cubs for their public debut. For more about the Zoo's growing pride and to watch them on live webcams: http://nationalzoo.si.edu/Animals/GreatCats/default.cfm?cam=LC4

The post Great Cats curator Craig Saffoe discusses his work caring for the National Zoo’s seven frisky lion cubs appeared first on Smithsonian Insider.

Maintaining natural movement of animals that live in the tropical rainforest canopy in South America is important for the health of the ecosystem. As development […]

The post Tremie Gregory uses camera traps to study “bridges” in the rainforest canopy appeared first on Smithsonian Insider.

When two red panda babies are born in critical condition at Smithsonian’s National Zoo, caretakers make the crucial decision to raise them by hand.

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Watch a keeper train the Zoo’s clouded leopard, Tai, for voluntary cheek swabs. The DNA from these cheek swabs is used to map the genealogy […]

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Now eight months old, Giant Panda Cub Bei Bei is learning to come when called and undergoing ‘target’ training to teach him to respond to […]

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“The Outwin 2016: American Portraiture Today” exhibition is on view at the Smithsonian’s National Portrait Gallery from March 12, 2016 – January 8, 2017. The Outwin […]

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Known around the world for personal and culturally inspired choreography, Dana Tai Soon Burgess has been named the Smithsonian’s first choreographer-in-residence at the National Portrait […]

The post Dana Tai Soon Burgess Dance Company @ Portrait Gallery appeared first on Smithsonian Insider.

A Guam rail chick hatched at the Smithsonian Conservation Biology Institute Jan. 16, 2018. The chick hatched in an incubator and will be hand-raised by […]

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On February 12, 2018, the Smithsonian’s National Portrait Gallery unveiled its commissioned portraits of former President Barack Obama and Mrs. Michelle Obama by artists Kehinde […]

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Curator Taína Caragol gives you a tour of a portrait of the late sculptor Luis Jiménez by Gaspar Enríquez at our National Portrait Gallery

The post Portraiture and the Mexican American Experience appeared first on Smithsonian Insider.

The discovery of starch granules in the calculus on Neandertal teeth provides direct evidence that they made sophisticated, thoughtful food choices and ate more nutrient-rich plants, for example date palms, legumes and grains such as barley.

The post Starch grains found on Neandertal teeth debunks theory that dietary deficiencies caused their extinction appeared first on Smithsonian Insider.

A team of scientists, including several from the Smithsonian Institution, discovered that leaves of flowering plants in the world's first rainforests had more veins per unit area than leaves ever had before.

The post First rainforests arose when plants solved their plumbing problem appeared first on Smithsonian Insider.

Bird species in rainforest fragments in Brazil that were isolated by deforestation first disappeared and then reappeared during the next quarter-century.

The post “Extinct” birds reappear in rainforest fragments in Brazil appeared first on Smithsonian Insider.