91 research outputs found

    Repulsive Osmotic Delamination : 1D Dissolution of 2D Materials

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    Abstract 2D materials have proved their potential in nearly every area of material science and chemistry. Unfortunately, large‐scale production of nanosheets is not straightforward. Current methods suffer from low yield, uncontrollable defects, and requires a high‐energy input. There is always a tradeoff between high quality and high yield. In this review, the alternative is highlighted to existing methods of 2D nanosheet production – 1D dissolution, historically known as osmotic swelling. As a thermodynamically driven, and therefore spontaneous, process it provides numerous benefits such as high aspect ratio and defect‐free nanosheets with a quantitative yield. In this review, the theory behind this process is discussed, compare it with the existing methods, and highlight the key features that allow to extend 1D dissolution to different charged layered materials. Moreover, the applications in which nanosheets obtained by 1D dissolution proved to be advantageous due to their unique, processing‐related features are discussed

    Rapid Low-Dimensional Li+Ion Hopping Processes in Synthetic Hectorite-Type Li0.5[Mg2.5Li0.5]Si4O10F2

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    Understanding the origins of fast ion transport in solids is important to develop new ionic conductors for batteries and sensors. Nature offers a rich assortment of rather inspiring structures to elucidate these origins. In particular, layer-structured materials are prone to show facile Li+ transport along their inner surfaces. Here, synthetic hectorite-type Li0.5[Mg2.5Li0.5]Si4O10F2, being a phyllosilicate, served as a model substance to investigate Li+ translational ion dynamics by both broadband conductivity spectroscopy and diffusion-induced 7Li nuclear magnetic resonance (NMR) spin-lattice relaxation experiments. It turned out that conductivity spectroscopy, electric modulus data, and NMR are indeed able to detect a rapid 2D Li+ exchange process governed by an activation energy as low as 0.35 eV. At room temperature, the bulk conductivity turned out to be in the order of 0.1 mS cm-1. Thus, the silicate represents a promising starting point for further improvements by crystal chemical engineering. To the best of our knowledge, such a high Li+ ionic conductivity has not been observed for any silicate yet

    Connecting Codes to ICON via the Community Interface (ComIn) - The Modular Earth Submodel System as a first complex ComIn plugin

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    The Modular Earth Submodel System (MESSy) is a software and a framework for the assembly of Earth System Models (ESMs). The MESSy software provides a modular kit with generalized interfaces for the standardized control and coupling of low-level ESM components. MESSy is applied successfully in several configurations coupled to several numerical weather and climate models, also connected to the ICOsahedral Non-hydrostatic model system (ICON) as base model. Because of the lack of an generalized interface, the connection of MESSy with the numerical models introduces additional hard-coded calls to MESSy subroutines in the base model code and several dependencies between the two codes. In a first natESM sprint, we used the novel Community Interface (ComIn) to break up direct dependencies of MESSy on the base model code and substitute the hard coded entry points in ICON with the functionality provided by ComIn. During the development of MESSy as ComIn compatible plugin, we explored restrictions of the approach and shortcomings of the underlying ComIn implementation. Giving direct feedback to the ComIn development process, improvements could be directly implemented in the interface and are available in the first ComIn release. Lessons learned from connecting the rather complex MESSy via ComIn also provide a blueprint for future ComIn plugin developments. This presentation will show the benefits of a generalized interface and a first application of ComIn on a "real-world" example

    Feasibility of Intestinal MR Elastography in Inflammatory Bowel Disease

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    Background: While MR enterography allows detection of inflammatory bowel disease (IBD), the findings continue to be of limited use in guiding treatment-medication vs. surgery. Purpose: To test the feasibility of MR elastography of the gut in healthy volunteers and IBD patients. Study type: Prospective pilot. Population: Forty subjects (healthy volunteers: n = 20, 37 ± 14 years, 10 women; IBD patients: n = 20 (ulcerative colitis n = 9, Crohn's disease n = 11), 41 ± 15 years, 11 women). Field strength/sequence: Multifrequency MR elastography using a single-shot spin-echo echo planar imaging sequence at 1.5 T with drive frequencies of 40, 50, 60, and 70 Hz. Assessment: Maps of shear-wave speed (SWS, in m/s) and loss angle (φ, in rad), representing stiffness and solid-fluid behavior, respectively, were generated using tomoelastography data processing. Histopathological analysis of surgical specimens was used as reference standard in patients. Statistical tests: Unpaired t-test, one-way analysis of variance followed by Tukey post hoc analysis, Pearson's correlation coefficient and area under the receiver operating characteristic curve (AUC) with 95%-confidence interval (CI). Significance level of 5%. Results: MR elastography was feasible in all 40 subjects (100% technical success rate). SWS and φ were significantly increased in IBD by 21% and 20% (IBD: 1.45 ± 0.14 m/s and 0.78 ± 0.12 rad; healthy volunteers: 1.20 ± 0.14 m/s and 0.65 ± 0.06 rad), whereas no significant differences were found between ulcerative colitis and Crohn's disease (P = 0.74 and 0.90, respectively). In a preliminary assessment, a high diagnostic accuracy in detecting IBD was suggested by an AUC of 0.90 (CI: 0.81-0.96) for SWS and 0.84 (CI: 0.71-0.95) for φ. Data conclusion: In this pilot study, our results demonstrated the feasibility of MR elastography of the gut and showed an excellent diagnostic performance in predicting IBD. Evidence level: 1 TECHNICAL EFFICACY: Stage 1

    Longitudinal changes in juvenile and adolescent body mass indices before, during, and after the COVID-19 lockdown in New Zealand.

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    This study uses longitudinal data from school children in Dunedin, New Zealand, to evaluate impacts of COVID-19 lockdown measures on changes in body mass (BMI, kg/m ). Impacts are assessed using two non-mutually exclusive hypotheses. The "structured days" hypothesis holds that children tend to alter sleep patterns, reduce activity and increase snacking when not in structured environments. The bidirectional hypothesis proposes that over-weight or obese children are predisposed to further gains in unstructured settings. Juveniles and adolescents (n = 95, 60% female) were recruited from Dunedin schools. Repeated measures analyses assessed variation in intra-individual change in BMI during four periods: P1 (before summer break), P2 (during summer break), P3 (during the COVID-19 lockdown), and P4 (after the lockdown ended). The model also examined if these changes were influenced by participants' sex or body size early in the first period assessed using log-transformed BMI, log-transformed weight, height, or lower leg length. Repeated measures analyses of per month gains in BMI (kg/m ) during the four periods revealed consistent period (p ≤ .001), period by sex (p ≤ .010), and period by body size (p ≤ .001) interactions across all four body size proxies. Both sexes experienced the greatest gains during the lockdown (P3), but differed in response to their summer break (P2). Results are mostly consistent with the "structured days" hypothesis, but challenge the bidirectional hypothesis as defined. Further research better characterizing risks of gains in adiposity are needed. [Abstract copyright: © 2023 The Authors. American Journal of Human Biology published by Wiley Periodicals LLC.
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