Kinetics of Graphene Growth on Liquid Copper by Chemical Vapor Deposition

We report a combined experimental and computational study of the kinetics of graphene growth during chemical vapor deposition on a liquid copper catalyst. The use of liquid metal catalysts offers bright perspectives for controllable large-scale, high-quality synthesis technologies of two-dimensional materials. We carried out a series of growth experiments varying CH4-to-H2 pressure ratios and deposition temperature. By monitoring the graphene flake morphology in real time during growth using in situ optical microscopy in radiation mode, we explored the morphology and kinetics of the growth within a wide range of experimental conditions. Following an analysis of the flakes' growth rates, we conclude that the growth mode was attachment-limited. The attachment and detachment activation energies of carbon species are derived as 1.9 +- 0.3 eV and 2.0 +- 0.1 eV, respectively. We also conducted free-energy calculations by a moment tensor potential trained to density functional theory data. Our simulations propose that carbon dimers are most likely the active carbon species during growth, with attachment and detachment barriers of 1.71 +- 0.15 eV and 2.09 +- 0.02 eV, respectively, being in good agreement with the experimental results

Combined scanning probe microscopy and x-ray scattering instrument for in situ catalysis investigations

Catalysis and Surface Chemistr

The MOSDEF Survey: Untangling the Emission-line Properties of z ∼ 2.3 Star-forming Galaxies

We analyze the rest-optical emission-line spectra of z∼2.3 star-forming galaxies in the complete MOSFIRE Deep Evolution Field (MOSDEF) survey. In investigating the origin of the well-known offset between the sequences of high-redshift and local galaxies in the [O III]5008/Hβ vs. [N II]6585/Hα ("[N II] BPT") diagram, we define two populations of z∼2.3 MOSDEF galaxies. These include the "high" population that is offset towards higher [O III]5008/Hβ and/or [N II]6585/Hα with respect to the local SDSS sequence and the "low" population that overlaps the SDSS sequence. These two groups are also segregated within the [O III]5008/Hβ vs. [S II]6718,6733/Hα and the [O III]4960,5008/[O II]3727,3730 (O32) vs. ([O III]4960,5008+[O II]3727,3730)/Hβ (R23) diagram, which suggests qualitatively that star-forming regions in the more offset galaxies are characterized by harder ionizing spectra at fixed nebular oxygen abundance. We also investigate many galaxy properties of the split sample and find that the "high" sample is on average smaller in size and less massive, but has higher specific star-formation rate and star-formation-rate surface density values and is slightly younger compared to the "low" population. From Cloudy+BPASS photoionization models, we estimate that the "high" population has a lower stellar metallicity (i.e., harder ionizing spectrum) but slightly higher nebular metallicity and higher ionization parameter compared to the "low" population. While the "high" population is more α-enhanced (i.e., higher α/Fe) than the "low" population, both samples are significantly more α-enhanced compared to local star-forming galaxies with similar rest-optical line ratios. These differences must be accounted for in all high-redshift star-forming galaxies -- not only those "offset" from local excitation sequences

The MOSDEF Survey: Neon as a Probe of ISM Physical Conditions at High Redshift

We present results on the properties of neon emission in $z\sim2$ star-forming galaxies drawn from the MOSFIRE Deep Evolution Field (MOSDEF) survey. Doubly-ionized neon ([NeIII]3869) is detected at $\geq3\sigma$ in 61 galaxies, representing $\sim$25% of the MOSDEF sample with H$\alpha$, H$\beta$, and [OIII]$5007$ detections at similar redshifts. We consider the neon emission-line properties of both individual galaxies with [NeIII]3869 detections and composite $z\sim2$ spectra binned by stellar mass. With no requirement of [NeIII]3869 detection, the latter provide a more representative picture of neon emission-line properties in the MOSDEF sample. The [NeIII]3869/[OII]3727 ratio (Ne3O2) is anti-correlated with stellar mass in $z\sim2$ galaxies, as expected based on the mass-metallicity relation. It is also positively correlated with the [OIII]$5007$/[OII]$3727$ ratio (O32), but $z\sim2$ line ratios are offset towards higher Ne3O2 at fixed O32, compared with both local star-forming galaxies and individual H~II regions. Despite the offset towards higher Ne3O2 at fixed O32 at $z\sim2$, biases in inferred Ne3O2-based metallicity are small. Accordingly, Ne3O2 may serve as an important metallicity indicator deep into the reionization epoch. Analyzing additional rest-optical line ratios including [NeIII]$3869$/[OIII]$5007$ (Ne3O3) and [OIII]$5007$/H$\beta$ (O3H$\beta$), we conclude that the nebular emission-line ratios of $z\sim2$ star-forming galaxies suggest a harder ionizing spectrum (lower stellar metallicity, i.e., Fe/H) at fixed gas-phase oxygen abundance, compared to systems at $z\sim0$. These new results based on neon lend support to the physical picture painted by oxygen, nitrogen, hydrogen, and sulfur emission, of an ionized ISM in high-redshift star-forming galaxies irradiated by chemically young, $\alpha$-enhanced massive stars.Comment: 7 pages, 5 figures, accepted to ApJ Letter

Variation in hospital admission in febrile children evaluated at the Emergency Department (ED) in Europe : PERFORM, a multicentre prospective observational study

Funding Information: This project was funded by the European Union?s Horizon 2020 research and innovation programme to ML (Grant No. 668303), the NIHR Newcastle Biomedical Research Centre at Newcastle Hospitals NHS foundation trust to ME, and the National Institute for Health Research to RGN (CL-2018-21-007). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Publisher Copyright: © 2021 Borensztajn et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.OBJECTIVES: Hospitalisation is frequently used as a marker of disease severity in observational Emergency Department (ED) studies. The comparison of ED admission rates is complex in potentially being influenced by the characteristics of the region, ED, physician and patient. We aimed to study variation in ED admission rates of febrile children, to assess whether variation could be explained by disease severity and to identify patient groups with large variation, in order to use this to reduce unnecessary health care utilization that is often due to practice variation. DESIGN: MOFICHE (Management and Outcome of Fever in children in Europe, part of the PERFORM study, www.perform2020.org), is a prospective cohort study using routinely collected data on febrile children regarding patient characteristics (age, referral, vital signs and clinical alarming signs), diagnostic tests, therapy, diagnosis and hospital admission. SETTING AND PARTICIPANTS: Data were collected on febrile children aged 0-18 years presenting to 12 European EDs (2017-2018). MAIN OUTCOME MEASURES: We compared admission rates between EDs by using standardised admission rates after adjusting for patient characteristics and initiated tests at the ED, where standardised rates >1 demonstrate higher admission rates than expected and rates <1 indicate lower rates than expected based on the ED patient population. RESULTS: We included 38,120 children. Of those, 9.695 (25.4%) were admitted to a general ward (range EDs 5.1-54.5%). Adjusted standardised admission rates ranged between 0.6 and 1.5. The largest variation was seen in short admission rates (0.1-5.0), PICU admission rates (0.2-2.2), upper respiratory tract infections (0.4-1.7) and fever without focus (0.5-2.7). Variation was small in sepsis/meningitis (0.9-1.1). CONCLUSIONS: Large variation exists in admission rates of febrile children evaluated at European EDs, however, this variation is largely reduced after correcting for patient characteristics and therefore overall admission rates seem to adequately reflect disease severity or a potential for a severe disease course. However, for certain patient groups variation remains high even after adjusting for patient characteristics.publishersversionPeer reviewe

Rapid Viral Testing and Antibiotic Prescription in Febrile Children with Respiratory Symptoms Visiting Emergency Departments in Europe

Funding Information: This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 668303 and No. 848196. The Research was supported by the National Institute for Health Research Biomedical Research Centres at Imperial College London, Newcastle Hospitals NHS Foundation Trust and Newcastle University. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health. For the remaining authors no sources of funding were declared. Publisher Copyright: Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.Background. Inappropriate antibiotic prescribing often occurs in children with self-limiting respiratory tract infections, contributing to antimicrobial resistance. It has been suggested that rapid viral testing can reduce inappropriate antibiotic prescribing. We aimed to assess the association between rapid viral testing at the Emergency Department (ED) and antibiotic prescription in febrile children. Methods. This study is part of the MOFICHE study, which is an observational multicenter study including routine data of febrile children (0-18 years) attending 12 European EDs. In children with respiratory symptoms visiting 6 EDs equipped with rapid viral testing, we performed multivariable logistic regression analysis regarding rapid viral testing and antibiotic prescription adjusted for patient characteristics, disease severity, diagnostic tests, focus of infection, admission, and ED. Results. A rapid viral test was performed in 1061 children (8%) and not performed in 11,463 children. Rapid viral test usage was not associated with antibiotic prescription (aOR 0.9, 95% CI: 0.8-1.1). A positive rapid viral test was associated with less antibiotic prescription compared with children without test performed (aOR 0.6, 95% CI: 0.5-0.8), which remained significant after adjustment for CRP and chest radiograph result. Twenty percent of the positively tested children received antibiotics. A negative rapid viral test was not associated with antibiotic prescription (aOR 1.2, 95% CI: 1.0-1.4). Conclusions. Rapid viral test usage did not reduce overall antibiotic prescription, whereas a positive rapid viral test did reduce antibiotic prescription at the ED. Implementation of rapid viral testing in routine emergency care and compliance to the rapid viral test outcome will reduce inappropriate antibiotic prescribing at the ED.publishersversionPeer reviewe

A NICE combination for predicting hospitalisation at the Emergency Department : a European multicentre observational study of febrile children

Funding Information: DB, UB, EC, JD, ME, MF, NH, BK, FMT, HM, EL, ML, MP, IRC, FS, MT, CV, SY, DZ and WZ report grants from the European Union. Horizon 2020 research and innovation programme during the study conduct. FS reports a grant from the Slovenian Research Agency outside the submitted work. Funding Information: MP reports a grant from Pfizer and financial support from Pfizer and Sanofi outside the submitted work. MF reports a grant from CSL Behring outside the submitted work. RN reports a grant from the National Institute for Health Research during the study conduct. ME reports financial support from the National Institute for Health Research Biomedical Research Centre based at Newcastle Hospitals NHS Foundation Trust and Newcastle University ng the study conduct. MT is a member of the Advisory Board of MSD and Pfizer, a member of the National Committee on Immunization Practices and a member of the national Scientific Advisory Group for the management of the pandemic. Publisher Copyright: © 2021 The Author(s)Background: Prolonged Emergency Department (ED) stay causes crowding and negatively impacts quality of care. We developed and validated a prediction model for early identification of febrile children with a high risk of hospitalisation in order to improve ED flow. Methods: The MOFICHE study prospectively collected data on febrile children (0–18 years) presenting to 12 European EDs. A prediction models was constructed using multivariable logistic regression and included patient characteristics available at triage. We determined the discriminative values of the model by calculating the area under the receiver operating curve (AUC). Findings: Of 38,424 paediatric encounters, 9,735 children were admitted to the ward and 157 to the PICU. The prediction model, combining patient characteristics and NICE alarming, yielded an AUC of 0.84 (95%CI 0.83-0.84). The model performed well for a rule-in threshold of 75% (specificity 99.0% (95%CI 98.9-99.1%, positive likelihood ratio 15.1 (95%CI 13.4-17.1), positive predictive value 0.84 (95%CI 0.82-0.86)) and a rule-out threshold of 7.5% (sensitivity 95.4% (95%CI 95.0-95.8), negative likelihood ratio 0.15 (95%CI 0.14-0.16), negative predictive value 0.95 (95%CI 0.95-9.96)). Validation in a separate dataset showed an excellent AUC of 0.91 (95%CI 0.90- 0.93). The model performed well for identifying children needing PICU admission (AUC 0.95, 95%CI 0.93-0.97). A digital calculator was developed to facilitate clinical use. Interpretation: Patient characteristics and NICE alarming signs available at triage can be used to identify febrile children at high risk for hospitalisation and can be used to improve ED flow. Funding: European Union, NIHR, NHS.publishersversionPeer reviewe