Ab initio van der Waals interactions in simulations of water alter structure from mainly tetrahedral to high-density-like

The structure of liquid water at ambient conditions is studied in ab initio molecular dynamics simulations using van der Waals (vdW) density-functional theory, i.e. using the new exchange-correlation functionals optPBE-vdW and vdW-DF2. Inclusion of the more isotropic vdW interactions counteracts highly directional hydrogen-bonds, which are enhanced by standard functionals. This brings about a softening of the microscopic structure of water, as seen from the broadening of angular distribution functions and, in particular, from the much lower and broader first peak in the oxygen-oxygen pair-correlation function (PCF), indicating loss of structure in the outer solvation shells. In combination with softer non-local correlation terms, as in the new parameterization of vdW-DF, inclusion of vdW interactions is shown to shift the balance of resulting structures from open tetrahedral to more close-packed. The resulting O-O PCF shows some resemblance with experiment for high-density water (A. K. Soper and M. A. Ricci, Phys. Rev. Lett., 84:2881, 2000), but not directly with experiment for ambient water. However, an O-O PCF consisting of a linear combination of 70% from vdW-DF2 and 30% from experiment on low-density liquid water reproduces near-quantitatively the experimental O-O PCF for ambient water, indicating consistency with a two-liquid model with fluctuations between high- and low-density regions

A new tool to assess Clinical Diversity In Meta‐analyses (CDIM) of interventions

OBJECTIVE: To develop and validate Clinical Diversity In Meta-analyses (CDIM), a new tool for assessing clinical diversity between trials in meta-analyses of interventions.STUDY DESIGN AND SETTING: The development of CDIM was based on consensus work informed by empirical literature and expertise. We drafted the CDIM tool, refined it, and validated CDIM for interrater scale reliability and agreement in three groups.RESULTS: CDIM measures clinical diversity on a scale that includes four domains with 11 items overall: setting (time of conduct/country development status/units type); population (age, sex, patient inclusion criteria/baseline disease severity, comorbidities); interventions (intervention intensity/strength/duration of intervention, timing, control intervention, cointerventions); and outcome (definition of outcome, timing of outcome assessment). The CDIM is completed in two steps: first two authors independently assess clinical diversity in the four domains. Second, after agreeing upon scores of individual items a consensus score is achieved. Interrater scale reliability and agreement ranged from moderate to almost perfect depending on the type of raters.CONCLUSION: CDIM is the first tool developed for assessing clinical diversity in meta-analyses of interventions. We found CDIM to be a reliable tool for assessing clinical diversity among trials in meta-analysis.</p

Reporting of methodological studies in health research : a protocol for the development of the MethodologIcal STudy reportIng Checklist (MISTIC)

CITATION: Lawson, Daeria O. et al. 2020. Reporting of methodological studies in health research : a protocol for the development of the MethodologIcal STudy reportIng Checklist (MISTIC). BMJ Open. 10(12):e040478, doi:10.1136/bmjopen-2020-040478.The original publication is available at: https://bmjopen.bmj.comIntroduction Methodological studies (ie, studies that evaluate the design, conduct, analysis or reporting of other studies in health research) address various facets of health research including, for instance, data collection techniques, differences in approaches to analyses, reporting quality, adherence to guidelines or publication bias. As a result, methodological studies can help to identify knowledge gaps in the methodology of health research and strategies for improvement in research practices. Differences in methodological study names and a lack of reporting guidance contribute to lack of comparability across studies and difficulties in identifying relevant previous methodological studies. This paper outlines the methods we will use to develop an evidence-based tool—the MethodologIcal STudy reportIng Checklist—to harmonise naming conventions and improve the reporting of methodological studies. Methods and analysis We will search for methodological studies in the Cumulative Index to Nursing and Allied Health Literature, Cochrane Library, Embase, MEDLINE, Web of Science, check reference lists and contact experts in the field. We will extract and summarise data on the study names, design and reporting features of the included methodological studies. Consensus on study terms and recommended reporting items will be achieved via video conference meetings with a panel of experts including researchers who have published methodological studies.Publisher's versio

Dealloying of Cobalt from CuCo Nanoparticles under Syngas Exposure

International audienceThe structure and composition of core−shell CuCo nanoparticles were found to change as a result of cleaning pretreatments and when exposed to syngas (CO + H 2) at atmospheric pressure. In situ X-ray absorption and photoelectron spectroscopies revealed the oxidation state of the particles as well as the presence of adsorbates under syngas. Transmission electron microscopy was used for ex situ analysis of the shape, elemental composition, and structure after reaction. The original core−shell structure was found to change to a hollow CuCo alloy after pretreatment by oxidation in pure O 2 and reduction in pure H 2. After 30 min of exposure to syngas, a significant fraction (5%) of the particles was strongly depleted in cobalt giving copper-rich nanoparticles. This fraction increased with duration of syngas exposure, a phenomenon that did not occur under pure CO or pure H 2. This study suggests that Co and Cu can each individually contribute to syngas conversion with CuCo catalysts

Ammonia Synthesis: State of the Bellwether Reaction

Catalytic ammonia synthesis has been judged to be one of mankind's greatest scientific achievements during the twentieth century. The socioeconomic implications of producing ammonia industrially have been a strong driving force, and this development has spurred a range of new discoveries within physics, chemistry, and chemical engineering. In this chapter, we describe how it has been possible in recent years to provide a full understanding of the catalytic ammonia synthesis reaction at the atomic level through the combined use of experiments and quantum mechanical electronic structure calculations, thus clearly showing many of the reasons why ammonia synthesis has been, and still is, the bellwether reaction in heterogeneous catalysis

Reporting of methodological studies in health research: a protocol for the development of the MethodologIcal STudy reportIng Checklist (MISTIC)

Introduction Methodological studies (ie, studies that evaluate the design, conduct, analysis or reporting of other studies in health research) address various facets of health research including, for instance, data collection techniques, differences in approaches to analyses, reporting quality, adherence to guidelines or publication bias. As a result, methodological studies can help to identify knowledge gaps in the methodology of health research and strategies for improvement in research practices. Differences in methodological study names and a lack of reporting guidance contribute to lack of comparability across studies and difficulties in identifying relevant previous methodological studies. This paper outlines the methods we will use to develop an evidence-based tool—the MethodologIcal STudy reportIng Checklist—to harmonise naming conventions and improve the reporting of methodological studies.Methods and analysis We will search for methodological studies in the Cumulative Index to Nursing and Allied Health Literature, Cochrane Library, Embase, MEDLINE, Web of Science, check reference lists and contact experts in the field. We will extract and summarise data on the study names, design and reporting features of the included methodological studies. Consensus on study terms and recommended reporting items will be achieved via video conference meetings with a panel of experts including researchers who have published methodological studies.Ethics and dissemination The consensus study has been exempt from ethics review by the Hamilton Integrated Research Ethics Board. The results of the review and the reporting guideline will be disseminated in stakeholder meetings, conferences, peer-reviewed publications, in requests to journal editors (to endorse or make the guideline a requirement for authors), and on the Enhancing the QUAlity and Transparency Of health Research (EQUATOR) Network and reporting guideline websites.Registration We have registered the development of the reporting guideline with the EQUATOR Network and publicly posted this project on the Open Science Framework (www.osf.io/9hgbq)