Periodic dispersion-corrected approach for isolation spectroscopy of N2 in an argon environment: Clusters, surfaces, and matrices

© 2017 American Chemical Society. Ab initio and Perdew, Burke, and Ernzerhof (PBE) density functional theory with dispersion correction (PBE-D3) calculations are performed to study N 2 -Ar n (n ≤ 3) complexes and N 2 trapped in Ar matrix (i.e., N 2 @Ar). For cluster computations, we used both Møller-Plesset (MP2) and PBE-D3 methods. For N 2 @Ar, we used a periodic-dispersion corrected model for Ar matrix, which consists on a slab of four layers of Ar atoms. We determined the equilibrium structures and binding energies of N 2 interacting with these entities. We also deduced the N 2 vibrational frequency shifts caused by clustering or embedding compared to an isolated N 2 molecule. Upon complexation or embedding, the vibrational frequency of N 2 is slightly shifted, while its equilibrium distance remains unchanged. This is due to the weak interactions between N 2 and Ar within these compounds. Our calculations show the importance of inclusion of dispersion effects for the accurate description of geometrical and spectroscopic parameters of N 2 isolated, in interaction with Ar surfaces, or trapped in Ar matrices

Implementing prescribing safety indicators in prisons: A mixed methods study

From Wiley via Jisc Publications RouterHistory: received 2021-08-20, rev-recd 2021-09-27, accepted 2021-09-30, pub-electronic 2021-10-29Article version: VoRPublication status: PublishedFunder: Greater Manchester Mental Health NHS Foundation TrustFunder: NIHR Greater Manchester Patient Safety Translational Research Centre; Id: http://dx.doi.org/10.13039/501100013235Funder: The Phoenix Partnership (TPP) LtdAims: To examine the prevalence of potentially hazardous prescribing in the prison setting using prescribing safety indicators (PSIs) and explore their implementation and use in practice. Methods: PSIs were identified and reviewed by the project team following a literature review and a nominal group discussion. Pharmacists at 2 prison sites deployed the PSIs using search protocols within their electronic health record. Prevalence rates and 95% confidence intervals (CIs) were generated for each indicator. Semi‐structured interviews with 20 prison healthcare staff across England and Wales were conducted to explore the feasibility of deploying and using PSIs in prison settings. Results: Thirteen PSIs were successfully deployed mostly comprising drug–drug interactions (n = 9). Five yielded elevated prevalence rates: use of anticholinergics if aged ≥65 years (Site B: 25.8% [95%CI: 10.4–41.2%]), lack of antipsychotic monitoring for >12 months (Site A: 39.1% [95%CI: 27.1–52.1%]; Site B: 28.6% [95%CI: 17.9–41.4%]), prolonged use of hypnotics (Site B: 46.3% [95%CI: 35.6–57.1%]), antiplatelets prescribed with nonsteroidal anti‐inflammatory drugs without gastrointestinal protection (Site A: 12.5% [95%CI: 0.0–35.4%]; Site B: 16.7% [95%CI: 0.4–64.1%]), and selective serotonin/norepinephrine reuptake inhibitors prescribed with nonsteroidal anti‐inflammatory drugs/antiplatelets without gastrointestinal protection (Site A: 39.6% [95%CI: 31.2–48.4%]; Site B: 33.3% [95%CI: 20.8–47.9%]). Prison healthcare staff supported the use of PSIs and identified key considerations to guide its successful implementation, including staff engagement and PSI 'champions'. To respond to PSI searches, stakeholders suggested contextualised patient support through intraprofessional collaboration. Conclusion: We successfully implemented a suite of PSIs into 2 prisons, identifying those with higher prevalence values as intervention targets. When appropriately resourced and integrated into staff workflow, PSI searches may support prescribing safety in prisons

Single-shot 3D coherent diffractive imaging of core-shell nanoparticles with elemental specificity

We report 3D coherent diffractive imaging (CDI) of Au/Pd core-shell nanoparticles with 6.1 nm spatial resolution with elemental specificity. We measured single-shot diffraction patterns of the nanoparticles using intense x-ray free electron laser pulses. By exploiting the curvature of the Ewald sphere and the symmetry of the nanoparticle, we reconstructed the 3D electron density of 34 core-shell structures from these diffraction patterns. To extract 3D structural information beyond the diffraction signal, we implemented a super-resolution technique by taking advantage of CDI's quantitative reconstruction capabilities. We used high-resolution model fitting to determine the Au core size and the Pd shell thickness to be 65.0 +/- 1.0 nm and 4.0 +/- 0.5 nm, respectively. We also identified the 3D elemental distribution inside the nanoparticles with an accuracy of 3%. To further examine the model fitting procedure, we simulated noisy diffraction patterns from a Au/Pd core-shell model and a solid Au model and confirmed the validity of the method. We anticipate this super-resolution CDI method can be generally used for quantitative 3D imaging of symmetrical nanostructures with elemental specificity.111Ysciescopu

Light-induced structural changes and the site of O=O bond formation in PSII caught by XFEL

Photosystem II (PSII) is a huge membrane-protein complex consisting of 20 different subunits with a total molecular mass of 350 kDa for a monomer. It catalyses light-driven water oxidation at its catalytic centre, the oxygen-evolving complex (OEC). The structure of PSII has been analysed at 1.9 Å resolution by synchrotron radiation X-rays, which revealed that the OEC is a Mn4CaO5 cluster organized in an asymmetric, 'distorted-chair' form. This structure was further analysed with femtosecond X-ray free electron lasers (XFEL), providing the 'radiation damage-free' structure. The mechanism of O=O bond formation, however, remains obscure owing to the lack of intermediate-state structures. Here we describe the structural changes in PSII induced by two-flash illumination at room temperature at a resolution of 2.35 Å using time-resolved serial femtosecond crystallography with an XFEL provided by the SPring-8 ångström compact free-electron laser. An isomorphous difference Fourier map between the two-flash and dark-adapted states revealed two areas of apparent changes: around the QB/non-haem iron and the Mn4CaO5 cluster. The changes around the QB/non-haem iron region reflected the electron and proton transfers induced by the two-flash illumination. In the region around the OEC, a water molecule located 3.5 Å from the Mn4CaO5 cluster disappeared from the map upon two-flash illumination. This reduced the distance between another water molecule and the oxygen atom O4, suggesting that proton transfer also occurred. Importantly, the two-flash-minus-dark isomorphous difference Fourier map showed an apparent positive peak around O5, a unique μ4-oxo-bridge located in the quasi-centre of Mn1 and Mn4 (refs 4,5). This suggests the insertion of a new oxygen atom (O6) close to O5, providing an O=O distance of 1.5 Å between these two oxygen atoms. This provides a mechanism for the O=O bond formation consistent with that proposed previousl

Periodic Dispersion-Corrected Approach for Isolation Spectroscopy of N 2 in an Argon Environment: Clusters, Surfaces, and Matrices

International audienc

Time-resolved photoelectron imaging using a femtosecond UV laser and a VUV free-electron laser

A time-resolved photoelectron imaging using a femtosecond ultraviolet (UV) laser and a vacuum UV freeelectron laser is presented. Ultrafast internal conversion and intersystem crossing in pyrazine in a supersonic molecular beam were clearly observed in the time profiles of photoioinzation intensity and time-dependent photoelectron images