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[en] The evolution of AR-NW12A into a multi-purpose end-station with optional high-pressure crystallography is described. The macromolecular crystallography (MX) beamline AR-NW12A is evolving from its original design of high-throughput crystallography to a multi-purpose end-station. Among the various options to be implemented, great efforts were made in making available high-pressure MX (HPMX) at the beamline. High-pressure molecular biophysics is a developing field that attracts the interest of a constantly growing scientific community. A plethora of activities can benefit from high pressure, and investigations have been performed on its applicability to study multimeric complex assemblies, compressibility of proteins and their crystals, macromolecules originating from extremophiles, or even the trapping of higher-energy conformers for molecules of biological interest. Recent studies using HPMX showed structural hydrostatic-pressure-induced changes in proteins. The conformational modifications could explain the enzymatic mechanism differences between proteins of the same family, living at different environmental pressures, as well as the initial steps in the pressure-denaturation process that have been attributed to water penetration into the protein interior. To facilitate further HPMX, while allowing access to various individualized set-ups and experiments, the AR-NW12A sample environment has been revisited. Altogether, the newly added implementations will bring a fresh breath of life to AR-NW12A and allow the MX community to experiment in a larger set of fields related to structural biology
[en] Highlights: • Several crystalline phases of thorium dichalcogenides are identified. • A series of structural and semiconductor-metal phase transitions are investigated. • The relationship of thermodynamic, mechanical and electronic properties among ThS2, ThSe2 and ThTe2 is studied. • The compounds become softer one after another from ThS2 to ThSe2 and then to ThTe2.
[en] Rare earth orthovanadates, RVO4 (R3+V5+O42-; R= rare earth element including Y and Sc) belongs to the family of ABO4 type compounds. At ambient pressure and temperature conditions, all the RVO4 compounds crystallize in zircon structure (except LaVO4 which can also be stabilized in monoclinic monazite structure). The basic building blocks of tetragonal zircon structure (space group: I41/amd ; Z=4) are VO4 tetrahedra and RO8 polyhedra which extend parallel to c axis and VO4 chains are joined laterally by edge sharing RO8. The V–O bond distance remains nearly the same for the entire lanthanide series, and the R–VO4 interaction is predominantly ionic. The RVO4 series represents an ideal system for studying the interaction between the sublattice of magnetic ions and the ligands of the host lattice. From technological point of view also these zircon-type orthovanadates have important applications as cathodoluminescence, thermophosphors, scintillators, and laser-host materials. They can also be useful for the development of green technologies through applications like photocatalytic hydrogen production. As is well known that pressure, an important thermodynamic variable can change the inter-atomic distances in the solids by an order of magnitude which dramatically alter the electronic properties, break existing bonds, or forming new chemical bonds which intern leads to variety of pressure-induced phenomena such as metallisation, amorphization, superconductivity and polymerisation. Hence, compression provides a unique possibility to control the structure and properties of materials. Usually the zircon-structured materials are known to transform to a denser (~10%) low symmetry tetragonal scheelite structure (space group I41/a) under pressure. On further compression this scheelite phase becomes unstable and system transforms to low symmetry monoclinic structure. In this talk evolution of equation of states and other structural details for various phases of RVO4 compounds studied using synchrotron based X-ray diffraction and Raman spectroscopic measurements will be presented.
[en] Highlights: • Characteristics of high pressure steel pipelines that are relevant to use of BS 7910 are reviewed. • Issues when assessing fracture of axial and circumferential cracks in pipelines are described. • Alternative approaches from other standards compared to those of BS 7910. • Suggestions made for improvements in the next edition of the standard.
[en] Highlights: • Shear viscosity of SF6 has been modeled (from 225.18 to 473.15 K up to 51.21 MPa). • Physically based viscosity models using from 1 to 6 parameters yield good results. • Effective repulsive steepness of the SF6 potential is higher than expected. - Abstract: Three recent physically based models (Lennard-Jones, free volume, thermodynamic scaling) for representing the viscosity of sulfur hexafluoride (SF6) are discussed together with two models (friction theory and Enskog 2σ) that have been recently applied to this fluid. The experimental database employed for adjustment (1562 data points) considers a large temperature (225.18 to 473.15 K) and pressure intervals (0.0264 to 51.21 MPa). The absolute average deviation is 3.8% for the Lennard-Jones model (one parameter), 1.7% for the free volume model (three parameters) and 1.5% for the thermodynamic scaling model (six parameters). Thus, it is shown that when physically based approaches are employed, a limited number of parameters is sufficient to represent accurately the shear viscosity of SF6. Furthermore it has been confirmed, using the thermodynamic scaling approach, that the repulsive steepness of the SF6 interaction potential is higher than usually found for fluids composed by non polar spherical molecule
[en] Conclusions: • Responding to design needs, the DACSDALMA code has been improved. • The instability test data of 1 MW DWT-SG were used for code verification. The details will be presented shorty. • Under high pressure conditions of 20 MPa like JSFR-SG, the Advanced Technology Experiment Sodium (Na) Facility (AtheNa) is planned to run dynamic stability tests in the near future
[en] This review provides an overview of high pressure crystallography using synchrotron radiation. Such experiments concern most of the scientific domains (Physics, Chemistry, Biology, Earth Science, Material Science…). After a description of the most used high pressure apparatus and of the different techniques of diffraction, adapted to high pressure environment, we present few examples of scientific results, selected from these different scientific domains. The perspective opened by recent experimental developments is also discussed. (review)
[en] High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low 1H and 13C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe2+)3Si2O5(OH)4), in contact with liquid water in water-saturated supercritical CO2 (scCO2) at 150 bar and 50 deg C. This mineral is relevant to the deep geologic disposal of CO2, but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.
[en] Selected cases will be presented of the superior performance of the HSE06 / PBEsol density functional calculations in reproduction of crystal and electronic structure as well as lattice dynamics of extended solids. Particular attention will be devoted to the cases when the ''industrial standard'' GGA-PBE calculations fail badly and provide misleading i.e. erroneous (qualitatively or quantitatively distorted) answers. The fascinating world of high pressure-driven phenomena, including the important issue of metallization of the chemical elements and compounds, will be addressed. Application of the HSE06/PBEsol tandem will then be extended to the seemingly well-established cases of polymorphism of the chemical elements, notably that of carbon. If time allows, selected aspects of the graphite-diamond transformation would be discussed.