iRadMat: A thermo-mechanical testing system for in situ high-energy X-ray characterization of radioactive specimens.

We present an in situ Radiated Materials (iRadMat) experimental module designed to interface with a servo-hydraulic load frame for X-ray measurements at beamline 1-ID at the Advanced Photon Source. This new capability allows in situ studies of radioactive specimens subject to thermo-mechanical loading using a suite of high-energy X-ray scattering and imaging techniques. The iRadMat is a radiation-shielded vacuum heating system with the sample rotation-under-load capability.

HBM Mice Have Altered Bone Matrix Composition and Improved Material Toughness.

The G171V mutation in the low-density lipoprotein receptor-related protein 5 (LRP5) leads to a high bone mass (HBM) phenotype. Studies using HBM transgenic mouse models have consistently found increased bone mass and whole-bone strength, but little attention has been paid to the composition of the bone matrix. The current study sought to determine if the cortical bone matrix composition differs in HBM and wild-type mice and to determine how much of the variance in bone material properties is explained by variance in matrix composition.

Maximum a posteriori estimation of crystallographic phases in X-ray diffraction tomography.

A maximum a posteriori approach is proposed for X-ray diffraction tomography for reconstructing three-dimensional spatial distribution of crystallographic phases and orientations of polycrystalline materials. The approach maximizes the a posteriori density which includes a Poisson log-likelihood and an a priori term that reinforces expected solution properties such as smoothness or local continuity. The reconstruction method is validated with experimental data acquired from a section of the spinous process of a porcine vertebra collected at the 1-ID-C beamline of the Advanced Photon Source, at Argonne National Laboratory.

Calcite orientations and composition ranges within teeth across Echinoidea.

Sea urchin's teeth from four families of order Echinoida and from orders Temnopleuroida, Arbacioida and Cidaroida were studied with synchrotron X-ray diffraction. The high and very high Mg calcite phases of the teeth, i.e.

Bone cell-independent benefits of raloxifene on the skeleton: a novel mechanism for improving bone material properties.

Raloxifene is an FDA approved agent used to treat bone loss and decrease fracture risk. In clinical trials and animal studies, raloxifene reduces fracture risk and improves bone mechanical properties, but the mechanisms of action remain unclear because these benefits occur largely independent of changes to bone mass. Using a novel experimental approach, machined bone beams, both from mature male canine and human male donors, were depleted of living cells and then exposed to raloxifene ex vivo.

In operando spatiotemporal study of Li(2)O(2) grain growth and its distribution inside operating Li-O(2) batteries.

Nanocrystalline lithium peroxide (Li2 O2 ) is considered to play a critical role in the redox chemistry during the discharge-charge cycling of the Li-O2 batteries. In this report, a spatially resolved, real-time synchrotron X-ray diffraction technique was applied to study the cyclic formation/decomposition of Li2 O2 crystallites in an operating Li-O2 cell. The evaluation of Li2 O2 grain size, concentration, and spatial distribution inside the cathode is demonstrated under the actual cycling conditions.

Crack-tip strain field mapping and the toughness of metallic glasses.

We have used high-energy x-ray scattering to map the strain fields around crack tips in fracture specimens of a bulk metallic glass under load at room temperature and below. From the measured strain fields we can calculate the components of the stress tensor as a function of position and determine the size and shape of the plastic process zone around the crack tip. Specimens tested at room temperature develop substantial plastic zones and achieve high stress intensities ((K(If) = 76 MPa m(1/2)) prior to fracture.

Quantitative determination of fragmentation kinetics and thermodynamics of colloidal silver nanowires by in situ high-energy synchrotron X-ray diffraction.

Colloidal silver nanowires become instable and tend to fragment into shortened nanorods and nanoparticles at elevated temperatures. Such morphological variations are associated with the transformation of crystalline structures from the body-centered tetragonal (b.c.

Effect of cyclic loading on the nanoscale deformation of hydroxyapatite and collagen fibrils in bovine bone.

Cyclic compressive loading tests were carried out on bovine femoral bones at body temperature (37 °C), with varying mean stresses (-55 to -80 MPa) and loading frequencies (0.5-5 Hz). At various times, the cyclic loading was interrupted to carry out high-energy X-ray scattering measurements of the internal strains developing in the hydroxyapatite (HAP) platelets and the collagen fibrils.

Reversibility of anodic lithium in rechargeable lithium-oxygen batteries.

Non-aqueous lithium-air batteries represent the next-generation energy storage devices with very high theoretical capacity. The benefit of lithium-air batteries is based on the assumption that the anodic lithium is completely reversible during the discharge-charge process. Here we report our investigation on the reversibility of the anodic lithium inside of an operating lithium-air battery using spatially and temporally resolved synchrotron X-ray diffraction and three-dimensional micro-tomography technique.

Effect of stress and temperature on the micromechanics of creep in highly irradiated bone and dentin.

Synchrotron X-ray diffraction is used to study in situ the evolution of phase strains during compressive creep deformation in bovine bone and dentin for a range of compressive stresses and irradiation rates, at ambient and body temperatures. In all cases, compressive strains in the collagen phase increase with increasing creep time (and concomitant irradiation), reflecting macroscopic deformation of the sample. By contrast, compressive elastic strains in the hydroxyapatite (HAP) phase, created upon initial application of compressive load on the sample, decrease with increasing time (and irradiation) for all conditions; this load shedding behavior is consistent with damage at the HAP-collagen interface due to the high irradiation doses (from ~100 to ~9,000 kGy).

Three-dimensional distribution of polymorphs and magnesium in a calcified underwater attachment system by diffraction tomography.

Biological materials display complicated three-dimensional hierarchical structures. Determining these structures is essential in understanding the link between material design and properties. Herein, we show how diffraction tomography can be used to determine the relative placement of the calcium carbonate polymorphs calcite and aragonite in the highly mineralized holdfast system of the bivalve Anomia simplex.

Effect of high-energy X-ray irradiation on creep mechanisms in bone and dentin.

Under long-term loading creep conditions, mineralized biological tissues like bone are expected to behave in a similar manner to synthetic composites where the creeping matrix sheds load to the elastic reinforcement as creep deformation progresses. To study this mechanism in biological composites, creep experiments were performed at 37 °C on bovine compact bone and dentin. Static compressive stresses were applied to the samples, while wide- and small-angle scattering patterns from high energy synchrotron X-rays were used to determine, respectively, the elastic strain in the hydroxyapatite (HAP) platelets and the strain in the mineralized collagen fibril, as a function of creep time.

Microfocused X-ray study on precipitate formation in the separator region of nonaqueous Li-O(2) batteries.

Using a microfocused synchrotron X-ray diffraction (μ-XRD) method, we systematically investigated the distributions of insoluble lithium precipitates, which formed through electrolyte decomposition, separately in all three regions (cathode, separator, and anode) of failed batteries with a spatial resolution of 20 μm. We found unexpectedly that there was a significantly higher concentration (almost twice as much) of precipitates in the separator than in the cathode. SEM revealed that the precipitates grew on the separator fiber surface, ultimately obstructing the pores serving as the ion-transport channel.

In situ mechanical behavior of mineral crystals in human cortical bone under compressive load using synchrotron X-ray scattering techniques.

It is of great interest to delineate the effect of orientation distribution of mineral crystals on the bulk mechanical behavior of bone. Using a unique synergistic approach combining a progressive loading scheme and synchrotron X-ray scattering techniques, human cortical bone specimens were tested in compression to examine the in situ mechanical behavior of mineral crystals aligned in different orientations. The orientation distribution was quantitatively estimated by measuring the X-ray diffraction intensity from the (002) plane in mineral crystals.

Sea urchin tooth mineralization: calcite present early in the aboral plumula.

In both vertebrate bone, containing carbonated hydroxyapatite as the mineral phase, and in invertebrate hard tissue comprised of calcium carbonate, a popular view is that the mineral phase develops from a long-lived amorphous precursor which later transforms into crystal form. Important questions linked to this popular view are: when and where is the crystallized material formed, and is amorphous solid added subsequently to the crystalline substrate? Sea urchin teeth, in which the earliest mineral forms within isolated compartments, in a time and position dependent manner, allow direct investigation of the timing of crystallization of the calcite primary plates. Living teeth of the sea urchin Lytechinus variegatus, in their native coelomic fluid, were examined by high-energy synchrotron X-ray diffraction.

Effect of X-ray irradiation on the elastic strain evolution in the mineral phase of bovine bone under creep and load-free conditions.

Both the load partitioning between hydroxyapatite (HAP) and collagen during compressive creep deformation of bone and the HAP residual strain in unloaded bone have been shown in previous synchrotron X-ray diffraction studies to be affected by the X-ray irradiation dose. Here, through detailed analysis of the X-ray diffraction patterns of bovine bone, the effect of X-ray dose on (i) the rate of HAP elastic strain accumulation/shedding under creep conditions and (ii) the HAP lattice spacing and average root mean square (RMS) strain under load-free conditions are examined. These strain measurements exhibit three stages in response to increasing X-ray dose.

Efficient simultaneous reverse Monte Carlo modeling of pair-distribution functions and extended x-ray-absorption fine structure spectra of crystalline disordered materials.

An efficient implementation of simultaneous reverse Monte Carlo (RMC) modeling of pair distribution function (PDF) and EXAFS spectra is reported. This implementation is an extension of the technique established by Krayzman et al. [J.

Nanophase evolution at semiconductor/electrolyte interface in situ probed by time-resolved high-energy synchrotron X-ray diffraction.

Real-time evolution of nanoparticles grown at the semiconductor/electrolyte interface formed between a single crystalline n-type GaAs wafer and an aqueous solution of AgNO(3) has been studied by using high-energy synchrotron X-ray diffraction. The results reveal the distinct nucleation and growth steps involved in the growth of anisotropic Ag nanoplates on the surface of the GaAs wafer. For the first time, a quick transit stage is observed to be responsible for the structural transformation of the nuclei to form structurally stable seeds that are critical for guiding their anisotropic growth into nanoplates.

A new model to simulate the elastic properties of mineralized collagen fibril.

Bone, because of its hierarchical composite structure, exhibits an excellent combination of stiffness and toughness, which is due substantially to the structural order and deformation at the smaller length scales. Here, we focus on the mineralized collagen fibril, consisting of hydroxyapatite plates with nanometric dimensions aligned within a protein matrix, and emphasize the relationship between the structure and elastic properties of a mineralized collagen fibril. We create two- and three-dimensional representative volume elements to represent the structure of the fibril and evaluate the importance of the parameters defining its structure and properties of the constituent mineral and collagen phase.