10 research outputs found

    Species Distribution During Solid Electrolyte Interphase Formation on Lithium Using MD/DFT-Parameterized Kinetic Monte Carlo Simulations

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    Lithium metal batteries are one of the promising technologies for future energy storage. One open challenge is the generation of a stable and well performing Solid Electrolyte Interphase (SEI) between lithium metal and electrolyte. Understanding the complex interaction of reactions at the lithium surface and the resulting SEI is crucial for knowledge-driven improvement of the SEI. This study reveals the internal species distribution and geometrical aspects of the native SEI during formation by model-based analysis. To achieve this, a combination of molecular dynamics, density functional theory, and stand-alone 3D-kinetic Monte Carlo simulations is used. The kinetic Monte Carlo model determines the SEI growth features over a long time and length scale so that the SEI can be analyzed quantitatively. The simulation confirms the frequently postulated layered SEI structure arising from the decomposition of an ethylene carbonate/lithium hexafluorophosphate (2 M) electrolyte with lithium metal. These layers are not clearly separated, which is contrary to what is often reported. The gradient distribution of the species within the SEI therefore corresponds to a partly mosaic structured SEI at the borders of the layers. At the lithium surface, an inorganic layer of lithium fluoride and then lithium carbonate is observed, followed by an organic, more porous SEI layer consisting of lithium ethylene dicarbonate. Simulations further reveal the strong prevalence of corrosion processes of the metal, which provide more than 99% of the lithium for the SEI reaction processes. The salt contributes less than 1% to the SEI formation. Additionally, SEI formation below and above the initial interface was observable. The here presented novel modeling approach allows an unprecedented in-depth analysis of processes during native SEI formation that can be used to improve design for high battery performance and durability

    Characteristics and resource needs in patients with vestibular symptoms: a comparison of patients with symptoms of unknown versus determined origin

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    Background Vestibular symptoms are a frequent reason for presenting at the emergency department (ED). Underlying conditions range in severity from life-threatening to benign, but often remain undiagnosed despite extensive investigations. We aimed to identify clinical characteristics that are associated with ED consultations by patients with vestibular symptoms of unknown origin (VUO) and to quantify the ED resources consumed during the investigations. Methods This retrospective one-year, single-centre, cross-sectional study assessed ED consultations with patients whose chief complaint was 'vestibular symptoms'. Data on risk factors, clinical characteristics, management and ED resources were extracted from the administrative database and medical records. Consultations were grouped according to the discharge diagnosis as either VUO or non-VUO. We determined clinical factors associated with VUO and compared ED resource consumption by the two patient groups using multivariable analysis. Results A total of 1599 ED consultations were eligible. Of these, 14.3% (n = 229) were consultations with patients with VUO. Clinical characteristics included in the final multivariable model to determine associations with VUO were sensory disorders, aural fullness, improvement at rest, absence of situational provocation, pre-existing neurological conditions, and age < 65 years. Patients with VUO had higher total ED resource consumption in terms of physicians' work and radiology resources, as a result of more use of computed tomography and magnetic resonance imaging. Conclusion One in seven emergency patients with vestibular symptoms is dismissed without a diagnosis. Clinical characteristics of VUO patients are distinct from patients in whom a diagnosis was made in the ED. VUO triggers higher ED resource consumption, which can be justified if appropriately indicated

    Quo vadis multiscale modeling in reaction engineering? A perspective

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    This work reports the results of a perspective workshop held in summer 2021 discussing the current status and future needs for multiscale modeling in reaction engineering. This research topic is one of the most challenging and likewise most interdisciplinary in the chemical engineering community, today. Although it is progressing fast in terms of methods development, it is only slowly applied by most reaction engineers. Therefore, this perspective is aimed to promote this field and facilitate research and a common understanding. It involves the following areas: (1) reactors and cells with surface changes focusing on Density Functional Theory and Monte-Carlo simulations; (2) hierarchically-based microkinetic analysis of heterogeneous catalytic processes including structure sensitivity, microkinetic mechanism development, and parameter estimation; (3) coupling first-principles kinetic models and CFD simulations of catalytic reactors covering chemistry acceleration strategies and surrogate models; and finally (4) catalyst-reactor-plant systems with details on linking CFD with plant simulations, respectively. It therefore highlights recent achievements, challenges, and future needs for fueling this urgent research topic in reaction engineering

    Colorectal resection in emergency general surgery: An EAST multicenter trial

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    OBJECTIVE Evidence comparing stoma creation (STM) versus anastomosis after urgent or emergent colorectal resection is limited. This study examined outcomes after colorectal resection in emergency general surgery patients. METHODS This was an Eastern Association for the Surgery of Trauma-sponsored prospective observational multicenter study of patients undergoing urgent/emergent colorectal resection. Twenty-one centers enrolled patients for 11 months. Preoperative, intraoperative, and postoperative variables were recorded. ?2, Mann-Whitney U test, and multivariable logistic regression models were used to describe outcomes and risk factors for surgical complication/mortality. RESULTS A total of 439 patients were enrolled (ANST, 184; STM, 255). The median (interquartile range) age was 62 (53-71) years, and the median Charlson Comorbidity Index (CCI) was 4 (1-6). The most common indication for surgery was diverticulitis (28%). Stoma group was older (64 vs. 58 years, p \u3c 0.001), had a higher CCI, and were more likely to be immunosuppressed. Preoperatively, STM patients were more likely to be intubated (57 vs. 15, p \u3c 0.001), on vasopressors (61 vs. 13, p \u3c 0.001), have pneumoperitoneum (131 vs. 41, p \u3c 0.001) or fecal contamination (114 vs. 33, p \u3c 0.001), and had a higher incidence of elevated lactate (149 vs. 67, p \u3c 0.001). Overall mortality was 13%, which was higher in STM patients (18% vs. 8%, p = 0.02). Surgical complications were more common in STM patients (35% vs. 25%, p = 0.02). On multivariable analysis, management with an open abdomen, intraoperative blood transfusion, and larger hospital size were associated with development of a surgical complication, while CCI, preoperative vasopressor use, steroid use, open abdomen, and intraoperative blood transfusion were independently associated with mortality. CONCLUSION This study highlights a tendency to perform fecal diversion in patients who are acutely ill at presentation. There is a higher morbidity and mortality rate in STM patients. Independent predictors of mortality include CCI, preoperative vasopressor use, steroid use, open abdomen, and intraoperative blood transfusion. Following adjustment by clinical factors, method of colon management was not associated with surgical complications or mortality. LEVEL OF EVIDENCE Therapeutic study, level IV

    Colorectal resection in emergency general surgery: An EAST multicenter trial.

    No full text
    OBJECTIVE: Evidence comparing stoma creation (STM) versus anastomosis after urgent or emergent colorectal resection is limited. This study examined outcomes after colorectal resection in emergency general surgery patients. METHODS: This was an Eastern Association for the Surgery of Trauma-sponsored prospective observational multicenter study of patients undergoing urgent/emergent colorectal resection. Twenty-one centers enrolled patients for 11 months. Preoperative, intraoperative, and postoperative variables were recorded. χ, Mann-Whitney U test, and multivariable logistic regression models were used to describe outcomes and risk factors for surgical complication/mortality. RESULTS: A total of 439 patients were enrolled (ANST, 184; STM, 255). The median (interquartile range) age was 62 (53-71) years, and the median Charlson Comorbidity Index (CCI) was 4 (1-6). The most common indication for surgery was diverticulitis (28%). Stoma group was older (64 vs. 58 years, p \u3c 0.001), had a higher CCI, and were more likely to be immunosuppressed. Preoperatively, STM patients were more likely to be intubated (57 vs. 15, p \u3c 0.001), on vasopressors (61 vs. 13, p \u3c 0.001), have pneumoperitoneum (131 vs. 41, p \u3c 0.001) or fecal contamination (114 vs. 33, p \u3c 0.001), and had a higher incidence of elevated lactate (149 vs. 67, p \u3c 0.001). Overall mortality was 13%, which was higher in STM patients (18% vs. 8%, p = 0.02). Surgical complications were more common in STM patients (35% vs. 25%, p = 0.02). On multivariable analysis, management with an open abdomen, intraoperative blood transfusion, and larger hospital size were associated with development of a surgical complication, while CCI, preoperative vasopressor use, steroid use, open abdomen, and intraoperative blood transfusion were independently associated with mortality. CONCLUSION: This study highlights a tendency to perform fecal diversion in patients who are acutely ill at presentation. There is a higher morbidity and mortality rate in STM patients. Independent predictors of mortality include CCI, preoperative vasopressor use, steroid use, open abdomen, and intraoperative blood transfusion. Following adjustment by clinical factors, method of colon management was not associated with surgical complications or mortality. LEVEL OF EVIDENCE: Therapeutic study, level IV

    Make EU trade with Brazil sustainable

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    Brazil, home to one of the planet's last great forests, is currently in trade negotiations with its second largest trading partner, the European Union (EU). We urge the EU to seize this critical opportunity to ensure that Brazil protects human rights and the environment
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