Theoretical Studies of Anisotropic Melting of Ice Induced by Ultrafast Nonthermal Heating.

Water and ice are routinely studied with X-rays to reveal their diverse structures and anomalous properties. We employ a hybrid collisional-radiative/molecular-dynamics method to explore how femtosecond X-ray pulses interact with hexagonal ice. We find that ice makes a phase transition into a crystalline plasma where its initial structure is maintained up to tens of femtoseconds.

The package: computing the pair angle distribution function from fluctuation scattering data.

The pair angle distribution function (PADF) is a three- and four-atom correlation function that characterizes the local angular structure of disordered materials, particles or nanocrystalline materials. The PADF can be measured using X-ray or electron fluctuation diffraction data, which can be collected by scanning or flowing a structurally disordered sample through a focused beam. It is a natural generalization of established pair distribution methods, which do not provide angular information.

Age and sex-related variations in murine laryngeal microbiota.

The larynx undergoes significant age and sex-related changes in structure and function across the lifespan. Emerging evidence suggests that laryngeal microbiota influences immunological processes. Thus, there is a critical need to delineate microbial mechanisms that may underlie laryngeal physiological and immunological changes.

A retrospective observational study on characteristics, treatment patterns, and healthcare resource use of patients with myasthenia gravis in England.

Background: There are limited data on the real-world healthcare resource use (HCRU) and management costs of myasthenia gravis (MG) in England.

Objective: This study aims to assess the burden of disease for patients with MG in England.

Design: A retrospective, observational cohort study of adult patients diagnosed with MG, using data from the Hospital Episode Statistics data warehouse.

Pressure-Induced Metallization of BaH and the Effect of Hydrogenation.

Using optical spectroscopy, X-ray diffraction, and electrical transport measurements, we have studied the pressure-induced metallization in BaH and BaH. Our combined measurements suggest a structural phase transition from BaH-II to BaH-III accompanied by band gap closure and transformation to a metallic state at 57 GPa. The metallization is confirmed by resistance measurements as a function of the pressure and temperature.

Synthesis and characterization of XeAr2 under high pressure.

The binary Xe-Ar system has been studied in a series of high pressure diamond anvil cell experiments up to 60 GPa at 300 K. In-situ x-ray powder diffraction and Raman spectroscopy indicate the formation of a van der Waals compound, XeAr2, at above 3.5 GPa.

NMR indicates the N-termini of PSGL1 and CCR7 bind competitively to the chemokine CCL21.

Chemokines are from a family of secreted cytokines that direct the trafficking of immune cells to coordinate immune responses. Chemokines are involved in numerous disease states, including responding to infections, autoimmune disorders, and cancer metastasis. Ther are chemokines, like CCL21, that signal for cellular migration through the activation of G protein-coupled receptors, like CCR7, through interaction with the receptor's extracellular N-terminus, loops, and core of the receptor.

Probing ion-binding at a protein interface: Modulation of protein properties by ionic liquids.

Ions are important to modulate protein properties, including solubility and stability, through specific ion effects. Ionic liquids (ILs) are designer salts with versatile ion combinations with great potential to control protein properties. Although protein-ion binding of common metals is well-known, the IL effect on proteins is not well understood.

Automation of liquid crystal phase analysis for SAXS, including the rapid production of novel phase diagrams for SDS-water-PIL systems.

Lyotropic liquid crystal phases (LCPs) are widely studied for diverse applications, including protein crystallization and drug delivery. The structure and properties of LCPs vary widely depending on the composition, concentration, temperature, pH, and pressure. High-throughput structural characterization approaches, such as small-angle x-ray scattering (SAXS), are important to cover meaningfully large compositional spaces.

Chemically Assisted Precompression of Hydrogen Molecules in Alkaline-Earth Tetrahydrides.

Through a series of high pressure diamond anvil experiments, we report the synthesis of alkaline earth (Ca, Sr, Ba) tetrahydrides, and investigate their properties through Raman spectroscopy, X-ray diffraction, and density functional theory calculations. The tetrahydrides incorporate both atomic and quasi-molecular hydrogen, and we find that the frequency of the intramolecular stretching mode of the units downshifts from Ca to Sr and to Ba upon compression. The experimental results indicate that the larger the host cation, the longer the bond.

Observations of phase changes in monoolein during high viscous injection.

Serial crystallography of membrane proteins often employs high-viscosity injectors (HVIs) to deliver micrometre-sized crystals to the X-ray beam. Typically, the carrier medium is a lipidic cubic phase (LCP) media, which can also be used to nucleate and grow the crystals. However, despite the fact that the LCP is widely used with HVIs, the potential impact of the injection process on the LCP structure has not been reported and hence is not yet well understood.

Preferred orientation and its effects on intensity-correlation measurements.

Intensity-correlation measurements allow access to nanostructural information on a range of ordered and disordered materials beyond traditional pair-correlation methods. In real space, this information can be expressed in terms of a pair-angle distribution function (PADF) which encodes three- and four-body distances and angles. To date, correlation-based techniques have not been applied to the analysis of microstructural effects, such as preferred orientation, which are typically investigated by texture analysis.

Stability, flow alignment and a phase transition of the lipidic cubic phase during continuous flow injection.

Continuous flow injection is a key technology for serial crystallography measurements of protein crystals suspended in the lipidic cubic phase (LCP). To date, there has been little discussion in the literature regarding the impact of the injection process itself on the structure of the lipidic phase. This is despite the fact that the phase of the injection matrix is critical for the flow properties of the stream and potentially for sample stability.

Superionicity, disorder, and bandgap closure in dense hydrogen chloride.

Hydrogen bond networks play a crucial role in biomolecules and molecular materials such as ices. How these networks react to pressure directs their properties at extreme conditions. We have studied one of the simplest hydrogen bond formers, hydrogen chloride, from crystallization to metallization, covering a pressure range of more than 2.

High-temperature phase transitions in dense germanium.

Through a series of high-pressure x-ray diffraction experiments combined with in situ laser heating, we explore the pressure-temperature phase diagram of germanium (Ge) at pressures up to 110 GPa and temperatures exceeding 3000 K. In the pressure range of 64-90 GPa, we observe orthorhombic Ge-IV transforming above 1500 K to a previously unobserved high-temperature phase, which we denote as Ge-VIII. This high-temperature phase is characterized by a tetragonal crystal structure, space group I4/mmm.

SpaceOAR Hydrogel Spacer for Reducing Radiation Toxicity During Radiotherapy for Prostate Cancer. A Systematic Review.

Objective: To evaluate the association between SpaceOAR and radiation dosing, toxicity and quality-of-life vs no spacer across all radiotherapy modalities for prostate cancer.

Methods: A systematic search of the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase was performed from database inception through May 2020. Two reviewers independently screened titles/abstracts and full papers.

Synthesis of Weaire-Phelan Barium Polyhydride.

By combining pressures up to 50 GPa and temperatures of 1200 K, we synthesize the novel barium hydride, BaH, stable down to 27 GPa. We use Raman spectroscopy, X-ray diffraction, and first-principles calculations to determine that this compound adopts a highly symmetric structure with an unusual 5:1 hydrogen-to-barium ratio. This singular stoichiometry corresponds to the well-defined type-I clathrate geometry.

Synthesis of Superconducting Cobalt Trihydride.

The Co-H system has been investigated through high-pressure, high-temperature X-ray diffraction experiments combined with first-principles calculations. On compression of elemental cobalt in a hydrogen medium, we observe face-centered cubic cobalt hydride (CoH) and cobalt dihydride (CoH) above 33 GPa. Laser heating CoH in a hydrogen matrix at 75 GPa to temperatures in excess of ∼800 K produces cobalt trihydride (CoH) which adopts a primitive structure.

Counterintuitive effects of isotopic doping on the phase diagram of H-HD-D molecular alloy.

Molecular hydrogen forms the archetypical quantum solid. Its quantum nature is revealed by behavior which is classically impossible and by very strong isotope effects. Isotope effects between [Formula: see text], [Formula: see text], and HD molecules come from mass difference and the different quantum exchange effects: fermionic [Formula: see text] molecules have antisymmetric wavefunctions, while bosonic [Formula: see text] molecules have symmetric wavefunctions, and HD molecules have no exchange symmetry.

Complex Hydrogen Substructure in Semimetallic RuH.

When compressed in a matrix of solid hydrogen, many metals form compounds with increasingly high hydrogen contents. At high density, hydrogenic sublattices can emerge, which may act as low-dimensional analogues of atomic hydrogen. We show that at high pressures and temperatures, ruthenium forms polyhydride species that exhibit intriguing hydrogen substructures with counterintuitive electronic properties.

Author Correction: Band gap closure, incommensurability and molecular dissociation of dense chlorine.

The original version of this Article omitted references to previous experimental reports on solid hydrogen that are relevant for a full understanding of the context of the previous work. The added references are: 47. Akahama, Y.

Band gap closure, incommensurability and molecular dissociation of dense chlorine.

Diatomic elemental solids are highly compressible due to the weak interactions between molecules. However, as the density increases the intra- and intermolecular distances become comparable, leading to a range of phenomena, such as structural transformation, molecular dissociation, amorphization, and metallisation. Here we report, following the crystallization of chlorine at 1.

Direct Reaction between Copper and Nitrogen at High Pressures and Temperatures.

Transition-metal nitrides have applications in a range of technological fields. Recent experiments have shown that new nitrogen-bearing compounds can be accessed through a combination of high temperatures and pressures, revealing a richer chemistry than was previously assumed. Here, we show that at pressures above 50 GPa and temperatures greater than 1500 K  elemental copper reacts with nitrogen, forming copper diazenide (CuN).

Unusually complex phase of dense nitrogen at extreme conditions.

Nitrogen exhibits an exceptional polymorphism under extreme conditions, making it unique amongst the elemental diatomics and a valuable testing system for experiment-theory comparison. Despite attracting considerable attention, the structures of many high-pressure nitrogen phases still require unambiguous determination. Here, we report the structure of the elusive high-pressure high-temperature polymorph ι-N at 56 GPa and ambient temperature, determined by single crystal X-ray diffraction, and investigate its properties using ab initio simulations.