Visualization of texture components using .

Knowledge of the appearance of texture components and fibres in pole figures, in inverse pole figures and in Euler space is fundamental for texture analysis. For cubic crystal systems, such as steels, an extensive literature exists and, for example, the book by Matthies, Vinel & Helming [, (1987), Akademie-Verlag Berlin] provides an atlas to identify texture components. For lower crystal symmetries, however, equivalent comprehensive overviews that can serve as guidance for the interpretation of experimental textures do not exist.

Upgrading the LANSCE accelerator with a SNS RF-driven H ion source.

The LANSCE accelerator is currently powered by a filament-driven, biased converter-type H ion source that operates at 10%, the highest plasma duty factor for this type of source, using only ∼2.2 SCCM of H. The ion source needs to be replaced every 4 weeks, which takes up to 4 days.

Flow-through compression cell for small-angle and ultra-small-angle neutron scattering measurements.

In situ measurements of geological materials under compression and with hydrostatic fluid pressure are important in understanding their behavior under field conditions, which in turn provides critical information for application-driven research. In particular, understanding the role of nano- to micro-scale porosity in the subsurface liquid and gas flow is critical for the high-fidelity characterization of the transport and more efficient extraction of the associated energy resources. In other applications, where parts are produced by the consolidation of powders by compression, the resulting porosity and crystallite orientation (texture) may affect its in-use characteristics.

Oedometric Small-Angle Neutron Scattering: In Situ Observation of Nanopore Structure During Bentonite Consolidation and Swelling in Dry and Hydrous CO Environments.

Results of oedometric consolidation experiments linked with small-angle neutron scattering (SANS) measurements are presented, using SWy-2 Wyoming bentonite clay in dry and water-bearing N and CO atmospheres. Oedometric SANS involves deforming a porous sample under uniaxial strain conditions with applied axial force and internal pore pressure control, and combines with SANS for in situ observation of pore structure evolution and interaction. Scattering from both interlayer (clay intra-aggregate) and free (interaggregate) pores is observed, showing decreasing pore size with dry consolidation and interactions between interlayer and free pore types with swelling and consolidation.

Reversible Lifting of Surface Supported Lipid Bilayers with a Membrane-Spanning Nonionic Triblock Copolymer.

Neutron reflectometry was used to monitor structural variations in surface-supported dimyristoylphosphatidycholine (DMPC) bilayers induced by the addition of Triton X-100, a surfactant commonly used to aid solubilization of membrane proteins, and the coaddition of a membrane spanning nonionic amphiphilic triblock copolymer, (PEO-PPO-PEO, Pluronic F98). Surfactant addition causes slight compression of the bilayer thickness and the creation of a distinct EO layer that increases the hydrophilic layer proximal to the supporting substrate (i.e.

Unusual Mott transition in multiferroic PbCrO3.

The Mott insulator in correlated electron systems arises from classical Coulomb repulsion between carriers to provide a powerful force for electron localization. Turning such an insulator into a metal, the so-called Mott transition, is commonly achieved by "bandwidth" control or "band filling." However, both mechanisms deviate from the original concept of Mott, which attributes such a transition to the screening of Coulomb potential and associated lattice contraction.

X-ray reflectivity and grazing incidence diffraction studies of interaction between human adhesion/growth-regulatory galectin-1 and DPPE-GM1 lipid monolayer at an air/water interface.

The specific interaction of ganglioside GM1 with the homodimeric (prototype) endogenous lectin galectin-1 triggers growth regulation in tumor and activated effector T cells. This proven biorelevance directed interest to studying association of the lectin to a model surface, i.e.

Analysis of biosurfaces by neutron reflectometry: from simple to complex interfaces.

Because of its high sensitivity for light elements and the scattering contrast manipulation via isotopic substitutions, neutron reflectometry (NR) is an excellent tool for studying the structure of soft-condensed material. These materials include model biophysical systems as well as in situ living tissue at the solid-liquid interface. The penetrability of neutrons makes NR suitable for probing thin films with thicknesses of 5-5000 Å at various buried, for example, solid-liquid, interfaces [J.

Understanding dynamic changes in live cell adhesion with neutron reflectometry.

Neutron reflectometry (NR) was used to examine various live cells adhesion to quartz substrates under different environmental conditions, including flow stress. To the best of our knowledge, these measurements represent the first successful visualization and quantization of the interface between live cells and a substrate with sub-nanometer resolution. In our first experiments, we examined live mouse fibroblast cells as opposed to past experiments using supported lipids, proteins, or peptide layers with no associated cells.

Evidence for partial dynamical symmetries in atomic nuclei.

Symmetries in nature offer very simple descriptions of complex systems. Partial Dynamical Symmetries (PDS) can considerably broaden their relevance. To present the first extensive test of a PDS for nuclei, we compare an SU(3) PDS to gamma to ground band B(E2) values for 47 deformed nuclei.

Microstrain in tetragonal lead-zirconate-titanate: the effect of pressure on the ionic displacements.

Piezoelectric materials respond to external stimuli by adjusting atomic positions. In solid-solutions, the changes occurring in atomic scale are very complex since the short- and long-range order are different. Standard methods used in diffraction data analysis fail to model the short-range order accurately.

Crystal structure and encapsulation dynamics of ice II-structured neon hydrate.

Neon hydrate was synthesized and studied by in situ neutron diffraction at 480 MPa and temperatures ranging from 260 to 70 K. For the first time to our knowledge, we demonstrate that neon atoms can be enclathrated in water molecules to form ice II-structured hydrates. The guest Ne atoms occupy the centers of D2O channels and have substantial freedom of movement owing to the lack of direct bonding between guest molecules and host lattices.

Energy landscape of self-assembled superlattices of PbSe nanocrystals.

Self-assembly of nanocrystals (NCs) into superlattices is an intriguing multiscale phenomenon that may lead to materials with novel collective properties, in addition to the unique properties of individual NCs compared with their bulk counterparts. By using different dispersion solvents, we synthesized three types of PbSe NC superlattices--body-centered cubic (bcc), body-centered tetragonal (bct), and face-centered cubic (fcc)--as confirmed by synchrotron small-angle X-ray scattering. Solution calorimetric measurements in hexane show that the enthalpy of formation of the superlattice from dispersed NCs is on the order of -2 kJ/mol.

Nafion in Dilute Solvent Systems: Dispersion or Solution?

The morphology of Nafion (EW = 1000, Na form) in dilute solvents is investigated using small angle neutron scattering (SANS) and F NMR. SANS modeling indicates three types of particle morphology: (i) a well-defined cylindrical dispersion in glycerol and in ethylene glycol with different degrees of solvent penetration; (ii) a less-defined, highly solvated large particle (>200 nm) in water/isopropanol mixtures; and (iii) a random-coil conformation (true solution behavior) in -methylpyrrolidone. These distinct morphological characteristics of Nafion are consistent with the main and side chain mobilities measured by F NMR.

Decoration of microtubules in solution by the kinesin-14, Ncd.

The kinesin-14, Ncd, is a cellular motor involved in microtubule spindle assembly and contraction during mitosis and meiosis. Like other members of the kinesin superfamily, Ncd consists of two motor heads connected by a linker and a long cargo-carrying stalk. The motor heads hydrolyze ATP to ADP to provide the power stroke that moves them and the cargo along the microtubule.

Mechanistic aspects of propene epoxidation by hydrogen peroxide. Catalytic role of water molecules, external electric field, and zeolite framework of TS-1.

We have assessed various aspects of the epoxidation of propene by hydrogen peroxide, a reaction of considerable industrial importance, and elucidated some of the important factors that govern its mechanism. Quantum chemical calculations on the reactants, products, and transition states were performed both in the gas phase and using models to represent the TS-1 (titanosilicalite-1) catalyst. The reaction energy for the uncatalyzed process is computed as -52.

An experimental and theoretical study of the variation of 4f hybridization across the La1-xCexIn3 series.

Crystal structures of a series of La(1-x)Ce(x)In(3) (x = 0.02, 0.2, 0.

Cubic to tetragonal phase transformation in cold-compressed Pd nanocubes.

Pd nanocubes with an average side length of approximately 10 nm were compressed up to 24.8 GPa in a diamond-anvil cell (DAC). In situ synchrotron X-ray diffraction was used to monitor structural changes, and a face-centered cubic (fcc) to face-centered tetragonal (fct) distortion was observed for the first time.

A novel helical double-layered cobalt(II)-organic framework with tetranuclear [Co4(mu3-OH)2] clusters linked by an unsymmetrical pyridylbenzoate ligand.

A novel cobalt(II)-organic framework, [Co2(OH)(3,4-PBC)3]n (I), has been acquired by the reaction of CoO with an unsymmetrical pyridylbenzoate ligand, 3-pyrid-4-ylbenzoic acid (3,4-PBC). Single-crystal X-ray diffraction studies reveal that it is comprised of [CoII4(mu3-OH)2] clusters linked by the unsymmetrical ligand 3,4-PBC, forming a novel helical double-layered metal-organic architecture. A significant overall antiferromagnetic behavior has been observed for this compound.

High-pressure/low-temperature neutron scattering of gas inclusion compounds: progress and prospects.

Alternative energy resources such as hydrogen and methane gases are becoming increasingly important for the future economy. A major challenge for using hydrogen is to develop suitable materials to store it under a variety of conditions, which requires systematic studies of the structures, stability, and kinetics of various hydrogen-storing compounds. Neutron scattering is particularly useful for these studies.

X-ray-induced dissociation of H2O and formation of an O2-H2 alloy at high pressure.

When subjected to high pressure and extensive x-radiation, water (H2O) molecules cleaved, forming O-O and H-H bonds. The oxygen (O) and hydrogen (H) framework in ice VII was converted into a molecular alloy of O2 and H2. X-ray diffraction, x-ray Raman scattering, and optical Raman spectroscopy demonstrated that this crystalline solid differs from previously known phases.