Characterisation of order/disorder in mixed metal oxide catalyst materials by reverse Monte Carlo modelling of X-ray and neutron total scattering

A deep dive into structural disorder of cerium zirconium oxides relevant for catalysis is undertaken focusing on a reverse Monte Carlo approach driven by total scattering X-ray and neutron data collected at synchrotron facilities. Cation nano-domains and interstitial oxygen are discovered after a atomic scale solid solution Ce0.75Zr0.25O2 material is is heated to 1050 °C under H2 paired with a subsequent reoxidation via heating under air at 400 °C. An overall loss of oxygen storage capacity is observed and rationalised as consequence of the nanoscale cation segregation clearly outweighs the beneficial properties of the inclusion of interstitial oxygen. In another reverse Monte Carlo study relating to stoichiometric ceria zirconia it is shown that synthesis route dramatically impacts the presence and types of local cation structures observed as shown by Clapp configuration analysis. A statistical approach to characterising local structures within face centred cubic atomic arrangements. For the first time a κ-CeZrO4 phase, prepared by reduction at 1050 °C followed by oxidation at 400 °C, is modelled via a large box reverse Monte Carlo approach revealing significant cation and oxide disorder. The disorder relating to the cation sites are characterised and shown to be a heavily defected pyrochlore-like cation ordering. The oxide lattice disorder is shown to be myriad with significant concentrations of interstitial sites occupied, split sites and more generalised anisotropy within the oxide lattice present, shining light on the origins of the high oxygen storage capacity associated to κ-CeZrO4 materials prepared at relatively low reduction temperatures. The Ce0.5Zr0.5O2 transition to pyrochlore ordering at ~1000+ °C is observed in an in-situ X-ray pair distribution study and shows a distinct mis-alignment between changes in the local structure and the average cation ordered structure that is determined form the super lattice Bragg reflections

A new procedure for the template synthesis of metal nanowires

A new procedure for the fabrication of metal nanowires by template assisted electrodeposition using porous polycarbonate templates is described. A thin sputtered film of silver (≤15 nm) was deposited onto one side of the template. The silver seed layer was used to catalyse electroless copper deposition and a copper layer was grown on top (300 - 500 nm) in less than 10 min. The copper layer served to seal the pores of the template and to form an electrode of high electrical conductivity. The copper layer was easily removed with a chemical etchant to aid the release of the nanowires from the template mask after growth. To demonstrate the process, copper nanowires were prepared by controlled potential deposition and characterised by SEM and TEM. This new procedure has the ability to be applied to the preparation of a wide range of metallic nanostructures over a wide range of scales. It avoids the need for an extended vacuum deposition step and has the advantage of using low cost metals in a combined short vacuum / wet chemical process so as to form the critical electrode layer for nanowire growth

Omentalisation as adjunctive treatment of an infected femoral nonunion fracture: a case report

A three-year-old male working border collie with an infected femoral nonunion fracture was managed in a two-stage procedure involving debridement and omentalisation, followed by stabilisation with a bone plate and an autogenous cancellous bone graft. Osseous union was documented radiographically 16 weeks after surgery. Telephone follow-up one year later revealed the dog had returned to full working function without evidence of lameness. To the authors' knowledge, this is the first clinical case described in the veterinary literature using omentalisation as an adjunct to the management of an infected, biologically inactive nonunion fracture

Order and disorder in cerium-rich ceria-zirconia solid solutions revealed from reverse Monte Carlo analysis of neutron and X-ray total scattering

A reverse Monte Carlo analysis of neutron and x-ray total scattering data from two ceria-zirconia samples of composition Ce0.75Zr0.25O2 is performed to analyze the distribution of cations and to examine the possibility of oxide-ion disorder. For the first material, heated in air under moderate conditions (800 °C), the structure is a single-phase solid-solution with the statistical distribution of cations, but a local tetragonal symmetry is found, consistent with the different coordination preferences of Ce and Zr. For the second material, heated under H2 at 1050 °C followed by reoxidation at 400 °C, the structure shows a considerable disorder, with evidence for oxygen interstitials (Frenkel-ion defects) and a non-statistical distribution of cations with significantly higher concentrations of like–like cation nearest neighbors, highlighting the existence of cation-rich nano-domains. The results highlight the dynamic nature of this solid-solution, with structural evolution upon thermal treatment, which is of relevance to understanding its stability under redox catalytic conditions in practical applications

Perspectives in Post-Pandemic Employment for Emergency Medicine Trainees

Learning Objectives: To survey graduating EM residents on their perceptions of the EM job market and its effect on their desire to pursue fellowship training.Background: The COVID-19 pandemic has resulted in changes to the emergency medicine (EM) workforce which pose challenges to residents graduating from EM training programs. New graduates face increasing uncertainty in the search for their first job. EM graduates in 2020 and 2021 saw a notable decrease in opportunities compared to years prior. ACEP’s Workforce Study (April 2021) predicts a surplus of emergency physicians by 2030. Objectives: To survey graduating EM residents on their perceptions of the EM job market and its effect on their desire to pursue fellowship training.Methods: We surveyed senior residents (PGY2 and above) at three- and four-year EM residency programs in the greater NYC area. Paper surveys were mailed out to each of the programs with a return envelope; a virtual link to complete the survey was also made available. Surveys were distributed from August 2021 to November 2021 to 22 EM residency programs (695 residents). Participation was voluntary and anonymous. The only demographic information gathered was program name and PGY level.Results: A total of 412 senior residents from the 22 EM residency programs completed the survey. Of the 412 seniors, 183 were PGY2s, 174 were PGY3s, and 55 were PGY4s and 5s (we included responses from residents in combined EM/IM programs). Survey questions and results are summarized in Table 1. Compared to colleagues in previous years, graduating EM residents anticipated broadening their job search. 58% of those considering fellowship after residency stated that their interest in fellowship has increased due to anticipated challenges in the job market (difficulty securing a full-time attending position).Conclusions: The majority of senior residents expressed concern about the current and future EM job market. How and where EM graduates apply for jobs may be impacted as a result. These data may prove valuable to residency programs, institutions, physician groups, and EM-bound medical students