Publications by authors named "Emma E McBride"

Article Synopsis
  • The study uses 11.2 keV X-ray diffraction to observe the crystallization of supercooled liquid hydrogen below its melting point.
  • Researchers measured changes in the solid and liquid structures dynamically, allowing them to identify the lowest energy crystal forms and determine densities and temperatures.
  • Findings show evidence of Arrhenius-like growth kinetics in the stacking direction during the supercooling process.
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Laser-driven dynamic compression experiments of plastic materials have found surprisingly fast formation of nanodiamonds (ND) via X-ray probing. This mechanism is relevant for planetary models, but could also open efficient synthesis routes for tailored NDs. We investigate the release mechanics of compressed NDs by molecular dynamics simulation of the isotropic expansion of finite size diamond from different P-T states.

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Studies of laser-heated materials on femtosecond timescales have shown that the interatomic potential can be perturbed at sufficiently high laser intensities. For gold, it has been postulated to undergo a strong stiffening leading to an increase of the phonon energies, known as phonon hardening. Despite efforts to investigate this behavior, only measurements at low absorbed energy density have been performed, for which the interpretation of the experimental data remains ambiguous.

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An experimental platform for dynamic diamond anvil cell (dDAC) research has been developed at the High Energy Density (HED) Instrument at the European X-ray Free Electron Laser (European XFEL). Advantage was taken of the high repetition rate of the European XFEL (up to 4.5 MHz) to collect pulse-resolved MHz X-ray diffraction data from samples as they are dynamically compressed at intermediate strain rates (≤10 s), where up to 352 diffraction images can be collected from a single pulse train.

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Trait mindfulness is associated with well-being in college students, yet it is unclear whether these associations are consistent across demographics. Undergraduate students ( = 534; 33% nonwhite; Apr2018-Sep2019). A cross-sectional online survey was performed.

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Background: Although meditation and yoga have been associated with higher trait mindfulness in general, they may help practitioners cultivate different qualities of mindfulness that manifest in different trait mindfulness profile scores.

Primary Study Objective: This study tested the hypothesis that college students who practice both meditation and yoga report the highest overall trait mindfulness scores and also explored the possibility that scores on specific facets of mindfulness may differ as a function of the meditation or yoga experience.

Methods/design: The study used a cross-sectional online survey (n = 529).

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Extreme conditions inside ice giants such as Uranus and Neptune can result in peculiar chemistry and structural transitions, e.g., the precipitation of diamonds or superionic water, as so far experimentally observed only for pure C─H and HO systems, respectively.

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The lithium-palladium and lithium-palladium-hydrogen systems are investigated at high pressures at and above room temperature. Two novel lithium-palladium compounds are found below [Formula: see text]. An ambient temperature phase is tentatively assigned as [Formula: see text], with [Formula: see text] Å at 8.

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Objectives: The mindfulness stress buffering account posits mindfulness may benefit physical health by reducing stress. Previous research supports this account and suggests the non-judging facet of mindfulness may be most strongly associated with physical symptoms of stress, via lower perceived stress. The current replication study used structural equation modeling to analyze relationships between multiple facets of mindfulness, perceived stress, and physical symptoms of stress.

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Higher trait mindfulness may be associated with better cognitive functioning and academic achievement in college students. Although mediating mechanisms are unclear, lower stress levels could explain this relationship. Participants: Cross-sectional online survey (n = 534; 33% non-white; Apr 2018 - Sep 2019).

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The European XFEL delivers up to 27000 intense (>10 photons) pulses per second, of ultrashort (≤50 fs) and transversely coherent X-ray radiation, at a maximum repetition rate of 4.5 MHz. Its unique X-ray beam parameters enable groundbreaking experiments in matter at extreme conditions at the High Energy Density (HED) scientific instrument.

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It is qualitatively well known that kinetics related to nucleation and growth can shift apparent phase boundaries from their equilibrium value. In this work, we have measured this effect in Bi using time-resolved X-ray diffraction with unprecedented 0.25 ms time resolution, accurately determining phase transition pressures at compression rates spanning five orders of magnitude (10-10 GPa/s) using the dynamic diamond anvil cell.

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The ultrafast synthesis of ε-FeN in a diamond-anvil cell (DAC) from Fe and N under pressure was observed using serial exposures of an X-ray free electron laser (XFEL). When the sample at 5 GPa was irradiated by a pulse train separated by 443 ns, the estimated sample temperature at the delay time was above 1400 K, confirmed by transformation of α- to γ-iron. Ultimately, the Fe and N reacted uniformly throughout the beam path to form FeN, as deduced from its established equation of state (EOS).

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We investigate the phase diagram of lithium at temperatures of 200 to 400 K, to pressures over 100 GPa using x-ray diffraction in diamond anvil cells, covering the region in which the melting curve is disputed. To overcome degradation of the diamond anvils by dense lithium we utilize a rapid compression scheme taking advantage of the high flux available at modern synchrotrons. Our results show the hR1 and cI16 phases to be stable to higher temperature than previously reported.

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