The pendant took Grand Prize in the National Saul Bell Design Competition in 2008 and features a beautiful 3.76-ct pink tourmaline from Nigeria.

The post Pink tourmaline “Nautilus” pendant enters National Gem Collection appeared first on Smithsonian Insider.

During a press conference Friday, July 22 at the Smithsonian's National Air and Space Museum, NASA announced that Gale Crater will be the landing site for the Mars Science Laboratory. Scheduled to launch in late 2011 and arrive at Mars in August 2012, the Mars Science Laboratory is a rover that will assess the planet’s “habitability”—if it ever was, or is today, an environment able to support microbial life.

The post Gale Crater to be landing site for NASA’s Mars Science Laboratory appeared first on Smithsonian Insider.

More than 500 carats of rough diamonds were recently donated to the Department of Mineral Sciences of the Smithsonian’s Natural History Museum by Jewlers Mutual Insurance Co. of Neenah, Wis.

The post 500 carats of rough diamonds donated to Natural History Museum appeared first on Smithsonian Insider.

New images from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft show the moon's crust is being stretched, forming minute valleys in a few small areas on the lunar surface.

The post Photos reveal recent activity in moon’s crust appeared first on Smithsonian Insider.

The National Museum of Natural History will permanently display the Dom Pedro Aquamarine, which is the largest single piece of cut-gem aquamarine in the world, beginning Dec. 6.

The post Magnificent Dom Pedro aquamarine to go on view in the Smithsonian’s Natural History Museum appeared first on Smithsonian Insider.

The National Museum of Natural History’s gem collection has a new addition: the Cindy Chao Black Label Masterpiece Royal Butterfly Brooch. Created by Chao in […]

The post Butterfly Brooch Enters National Gem Collection appeared first on Smithsonian Insider.

The humble salamander may provide evidence to support a controversial claim that North and South America were joined together much earlier than previously thought. The […]

The post Salamander DNA reveals evidence of older land connection between Central and South America appeared first on Smithsonian Insider.

Miniature camels and horses, a rhinoceros and a giant bear-dog are among fossils unearthed in the recent excavations of the Panama Canal expansion project. These […]

The post First five years of Panama Canal excavations reveal fossil finds appeared first on Smithsonian Insider.

Forget what you thought you knew about geology. Some minerals can roll up like flaky Belgian piroulines. For the last several decades, mining operations in […]

The post Rolled-Up Mystery Mineral may cause Craving for Piroulines appeared first on Smithsonian Insider.

Everyone knows that the gravitational tugging of the moon makes earth’s oceans swell and recede. But did you know Earth’s tugging is causing the moon […]

The post Shrinking Moon Linked to Earth’s Tidal Forces appeared first on Smithsonian Insider.

Nearly four billion years ago, life arose on Earth. Life appeared because our planet had a rocky surface, liquid water, and a blanketing atmosphere. But […]

The post Sun-like Star Shows Magnetic Field Critical for Life on the early Earth appeared first on Smithsonian Insider.

Images obtained by NASA’s MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) spacecraft during the low-altitude orbital phase of the mission have revealed previously undetected […]

The post Mercury Joins Earth As Tectonically Active Planet appeared first on Smithsonian Insider.

Have an upset stomach? Pop a chalky, chewable antacid. Maybe you’ve got a painful cut or burn. No problem; reach for a healing ointment or […]

The post Glittering, mesmerizing, lifesaving: Hospital exhibit showcases minerals used in medicine appeared first on Smithsonian Insider.

The Pan-STARRS project at the University of Hawai’i Institute for Astronomy (UH IfA) is publicly releasing the world’s largest digital sky survey today from the […]

The post Pan-STARRS Releases Largest Digital Sky Survey to the World appeared first on Smithsonian Insider.

Several weeks before it went on display in mid-November at the Smithsonian’s National Museum of Natural History, minerals curator Jeff Post stood in the museum’s […]

The post Colossal diamond’s eerie glow earns it a fiery name appeared first on Smithsonian Insider.

In the battle against invasive species, giant commercial ships are on the front lines. But even when they follow the rules, one of their best […]

The post Battle against invasive marine species comes up short as global shipping surges appeared first on Smithsonian Insider.

Cambridge, MA -Physicists are capitalizing on a direct connection between the largest cosmic structures and the smallest known objects to use the universe as a […]

The post Scientists are using the universe as a “cosmological collider” appeared first on Smithsonian Insider.

As average annual temperatures increase, mosquitoes have also been on the move—up the mountains of the Hawaiian islands. Once a refuge for native birds susceptible […]

The post Scientists race to find genetic clues as malaria decimates rare Hawaiian honeycreepers appeared first on Smithsonian Insider.

Seven corrections are made and several supplementary equations are added to the article by Yoshimura [Acta Cryst. (2015), A71, 368–381].

Structural investigations of amorphous and nanocrystalline phases forming in solution are historically challenging. Few methods are capable of in situ atomic structural analysis and rigorous control of the system. A mixed-flow reactor (MFR) is used for total X-ray scattering experiments to examine the short- and long-range structure of phases in situ with pair distribution function (PDF) analysis. The adaptable experimental setup enables data collection for a range of different system chemistries, initial supersaturations and residence times. The age of the sample during analysis is controlled by adjusting the flow rate. Faster rates allow for younger samples to be examined, but if flow is too fast not enough data are acquired to average out excess signal noise. Slower flow rates form older samples, but at very slow speeds particles settle and block flow, clogging the system. Proper background collection and subtraction is critical for data optimization. Overall, this MFR method is an ideal scheme for analyzing the in situ structures of phases that form during crystal growth in solution. As a proof of concept, high-resolution total X-ray scattering data of amorphous and crystalline calcium phosphates and amorphous calcium carbonate were collected for PDF analysis.

Serial crystallography records still diffraction patterns from single, randomly oriented crystals, then merges data from hundreds or thousands of them to form a complete data set. To process the data, the diffraction patterns must first be indexed, equivalent to determining the orientation of each crystal. A novel automatic indexing algorithm is presented, which in tests usually gives significantly higher indexing rates than alternative programs currently available for this task. The algorithm does not require prior knowledge of the lattice parameters but can make use of that information if provided, and also allows indexing of diffraction patterns generated by several crystals in the beam. Cases with a small number of Bragg spots per pattern appear to particularly benefit from the new approach. The algorithm has been implemented and optimized for fast execution, making it suitable for real-time feedback during serial crystallography experiments. It is implemented in an open-source C++ library and distributed under the LGPLv3 licence. An interface to it has been added to the CrystFEL software suite.

Single-wavelength X-ray anomalous diffraction (SAD) is a frequently employed technique to solve the phase problem in X-ray crystallography. The precision and accuracy of recovered anomalous differences are crucial for determining the correct phases. Continuous rotation (CR) and inverse-beam geometry (IBG) anomalous data collection methods have been performed on tetragonal lysozyme and monoclinic survivin crystals and analysis carried out of how correlated the pairs of Friedel's reflections are after scaling. A multivariate Bayesian model for estimating anomalous differences was tested, which takes into account the correlation between pairs of intensity observations and incorporates the a priori knowledge about the positivity of intensity. The CR and IBG data collection methods resulted in positive correlation between I(+) and I(−) observations, indicating that the anomalous difference dominates between these observations, rather than different levels of radiation damage. An alternative pairing method based on near simultaneously observed Bijvoet's pairs displayed lower correlation and it was unsuccessful for recovering useful anomalous differences when using the multivariate Bayesian model. In contrast, multivariate Bayesian treatment of Friedel's pairs improved the initial phasing of the two tested crystal systems and the two data collection methods.

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.

This work studies the elastic scattering behavior of electron vortices when propagating through amorphous samples. A formulation of the multislice approach in cylindrical coordinates is used to theoretically investigate the redistribution of intensity between different angular momentum components due to scattering. To corroborate and elaborate on our theoretical results, extensive numerical simulations are performed on three model systems (Si3N4, Fe0.8B0.2, Pt) for a wide variety of experimental parameters to quantify the purity of the vortices, the net angular momentum transfer, and the variability of the results with respect to the random relative position between the electron beam and the scattering atoms. These results will help scientists to further improve the creation of electron vortices and enhance applications involving them.

A novel approach for finding and evaluating structural models of small metallic nanoparticles is presented. Rather than fitting a single model with many degrees of freedom, libraries of clusters from multiple structural motifs are built algorithmically and individually refined against experimental pair distribution functions. Each cluster fit is highly constrained. The approach, called cluster-mining, returns all candidate structure models that are consistent with the data as measured by a goodness of fit. It is highly automated, easy to use, and yields models that are more physically realistic and result in better agreement to the data than models based on cubic close-packed crystallographic cores, often reported in the literature for metallic nanoparticles.

The use of strongly bent crystals in spectrometers for pulses of a hard X-ray free-electron laser is explored theoretically. Diffraction is calculated in both dynamical and kinematical theories. It is shown that diffraction can be treated kinematically when the bending radius is small compared with the critical radius given by the ratio of the Bragg-case extinction length for the actual reflection to the Darwin width of this reflection. As a result, the spectral resolution is limited by the crystal thickness, rather than the extinction length, and can become better than the resolution of a planar dynamically diffracting crystal. As an example, it is demonstrated that spectra of the 12 keV pulses can be resolved in the 440 reflection from a 20 µm-thick diamond crystal bent to a radius of 10 cm.

The transformations from the primitive cells of the centered Bravais lattices to the corresponding centered cells have conventionally been listed as three-by-three matrices that transform three-space lattice vectors. Using those three-by-three matrices when working in the six-dimensional space of lattices represented as Selling scalars as used in Delone (Delaunay) reduction, one could transform to the three-space representation, apply the three-by-three matrices and then back-transform to the six-space representation, but it is much simpler to have the equivalent six-by-six matrices and apply them directly. The general form of the transformation from the three-space matrix to the corresponding matrix operating on Selling scalars (expressed in space S6) is derived, and the particular S6matrices for the centered Delone types are listed. (Note: in his later publications, Boris Delaunay used the Russian version of his surname, Delone.)

A crystallographic indexing algorithm, pinkIndexer, is presented for the analysis of snapshot diffraction patterns. It can be used in a variety of contexts including measurements made with a monochromatic radiation source, a polychromatic source or with radiation of very short wavelength. As such, the algorithm is particularly suited to automated data processing for two emerging measurement techniques for macromolecular structure determination: serial pink-beam X-ray crystallography and serial electron crystallography, which until now lacked reliable programs for analyzing many individual diffraction patterns from crystals of uncorrelated orientation. The algorithm requires approximate knowledge of the unit-cell parameters of the crystal, but not the wavelengths associated with each Bragg spot. The use of pinkIndexer is demonstrated by obtaining 1005 lattices from a published pink-beam serial crystallography data set that had previously yielded 140 indexed lattices. Additionally, in tests on experimental serial crystallography diffraction data recorded with quasi-monochromatic X-rays and with electrons the algorithm indexed more patterns than other programs tested.

X-ray emission under electron-channelling conditions is used to distinguish between a non-centrosymmetric half-Heusler and a centrosymmetric full-Heusler crystal. For TiCo1.5+xSn the space-group determination based on a Rietveld refinement procedure became challenging for increasing Co content (x > 0.2), while electron channelling proved successful for higher Co content (x = 0.35). This technique can be used on crystals as small as (10 nm)3.

In this study, the atomic structure of the ternary icosahedral ZnMgTm quasicrystal (QC) is investigated by means of single-crystal X-ray diffraction. The structure is found to be a member of the Bergman QC family, frequently found in Zn–Mg–rare-earth systems. The ab initio structure solution was obtained by the use of the Superflip software. The infinite structure model was founded on the atomic decoration of two golden rhombohedra, with an edge length of 21.7 Å, constituting the Ammann–Kramer–Neri tiling. The refined structure converged well with the experimental diffraction diagram, with the crystallographic R factor equal to 9.8%. The Bergman clusters were found to be bonded by four possible linkages. Only two linkages, b and c, are detected in approximant crystals and are employed to model the icosahedral QCs in the cluster approach known for the CdYb Tsai-type QC. Additional short b and a linkages are found in this study. Short interatomic distances are not generated by those linkages due to the systematic absence of atoms and the formation of split atomic positions. The presence of four linkages allows the structure to be pictured as a complete covering by rhombic triacontahedral clusters and consequently there is no need to define the interstitial part of the structure (i.e. that outside the cluster). The 6D embedding of the solved structure is discussed for the final verification of the model.

Crystal structure identification of thin organic films entails a number of technical and methodological challenges. In particular, if molecular crystals are epitaxially grown on single-crystalline substrates a complex scenario of multiple preferred orientations of the adsorbate, several symmetry-related in-plane alignments and the occurrence of unknown polymorphs is frequently observed. In theory, the parameters of the reduced unit cell and its orientation can simply be obtained from the matrix of three linearly independent reciprocal-space vectors. However, if the sample exhibits unit cells in various orientations and/or with different lattice parameters, it is necessary to assign all experimentally obtained reflections to their associated individual origin. In the present work, an effective algorithm is described to accomplish this task in order to determine the unit-cell parameters of complex systems comprising different orientations and polymorphs. This method is applied to a polycrystalline thin film of the conjugated organic material 6,13-pentacene­quinone (PQ) epitaxially grown on an Ag(111) surface. All reciprocal vectors can be allocated to unit cells of the same lattice constants but grown in various orientations [sixfold rotational symmetry for the contact planes (102) and (102)]. The as-determined unit cell is identical to that reported in a previous study determined for a fibre-textured PQ film. Preliminary results further indicate that the algorithm is especially effective in analysing epitaxially grown crystallites not only for various orientations, but also if different polymorphs are present in the film.

The generalized Darwin–Hamilton equations [Wuttke (2014). Acta Cryst. A70, 429–440] describe multiple Bragg reflection from a thick, ideally imperfect crystal. These equations are simplified by making full use of energy conservation, and it is demonstrated that the conventional two-ray Darwin–Hamilton equations are obtained as a first-order approximation. Then an efficient numeric solution method is presented, based on a transfer matrix for discretized directional distribution functions and on spectral collocation in the depth coordinate. Example solutions illustrate the orientational spread of multiply reflected rays and the distortion of rocking curves, especially if the detector only covers a finite solid angle.

As you read here
In a 24-hour-period between July 9 and 10, 2009 a clouded leopard cub, a Przewalski's horse, and a red panda cub were all born at Smithsonian's National Zoo's Conservation and Research Center in Front Royal, Virginia.

The post A clouded leopard cub, a Przewalski’s horse and a red panda cub were all recently born at the Smithsonian’s National Zoo appeared first on Smithsonian Insider.

Black holes sound wildly complicated. After all, there are all sorts of bizarre things going on: intense gravity, the warping of the fabric of space, the distortion of time itself. But when it comes to describing black holes, it comes down to just two numbers: the mass of the black hole and its spin. That’s right. Everything you physically need to describe a black hole is found in just these two numbers.

The post Black Holes, just two numbers is all you need… appeared first on Smithsonian Insider.

John Ososky, preparator in the Osteology Laboratory at the Smithsonian's National Museum of Natural History in Washington, D.C., explains how skeletons of animal specimens are prepared for exhibtion and for study—with the assistance of nearly 1 million flesh-eating beetles.

The post Flesh Eating beetles help prepare skeletons for study at the Smithsonian’s Natural History Museum appeared first on Smithsonian Insider.

Forensic anthropologists from the Smithsonian's National Museum of Natural History discover African remains at a Colonial burial site in Maryland. Follow them as they study the remains, reconstruct the face and body, and share what they learn about the African experience in the Chesapeake in the 1600s.

The post Smithsonian team examines African remains from a colonial burial site in Maryland appeared first on Smithsonian Insider.

George Smith, a marine biologist at the Smithsonian Environmental Research Center, explains his work of finding ways to prevent invasive species from being released in Baltimore Harbor in the ballast water of large ships.

The post Preventing ballast-water invasions of alien species appeared first on Smithsonian Insider.

The post Conservators challenged by contemporary artworks at the Hirshhorn Museum appeared first on Smithsonian Insider.

The post Meet Our Scientist: National Zoo veterinarian Katharine Hope appeared first on Smithsonian Insider.

Rick Wunderman of the Global Volcanism Program at the Smithsonian's National Museum of Natural History talks about the current volcanic activity in Iceland.

The post Smithsonian volcanologist Rick Wunderman talks about volcanos and the recent eruptions in Iceland appeared first on Smithsonian Insider.

Eyjafjallajökull's eruption may be a hassle if you had any transatlantic flights planned this summer. For scientists, however, volcanic eruptions are the only way they can obtain samples from deep within the Earth to learn more about our planet, its formation, and its ongoing evolution. Smithsonian Geologist Liz Cottrell helps put this recent eruption into perspective.

The post Geologist Liz Cottrell puts Eyjafjallajökull’s eruption into perspective appeared first on Smithsonian Insider.

Keeper Tracey Barnes talks about Billie Jean, an Andean bear, and her two new cubs at the Smithsonian's National Zoo.

The post Keeper Tracey Barnes talks about the National Zoo’s Andean bear, Billie Jean, and her two new cubs appeared first on Smithsonian Insider.

Dr. JoGayle Howard of the Smithsonian's National Zoo discusses her work to breed and study one of the world's most endangered cats, the clouded leopard. More about the National Zoo's work to save clouded leopards: http://nationalzoo.si.edu/SCBI/ReproductiveScience/ConsEn...
http://nationalzoo.si.edu/support/annualappeal/cloudedleo... ... (more info)

The post Meet Our Scientist: Dr. JoGayle Howard of the Smithsonian’s National Zoological Park appeared first on Smithsonian Insider.