106 research outputs found

    Cooperative Carbon Dioxide Adsorption in Alcoholamine- and Alkoxyalkylamine-Functionalized Metal-Organic Frameworks.

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    A series of structurally diverse alcoholamine- and alkoxyalkylamine-functionalized variants of the metal-organic framework Mg2 (dobpdc) are shown to adsorb CO2 selectively via cooperative chain-forming mechanisms. Solid-state NMR spectra and optimized structures obtained from van der Waals-corrected density functional theory calculations indicate that the adsorption profiles can be attributed to the formation of carbamic acid or ammonium carbamate chains that are stabilized by hydrogen bonding interactions within the framework pores. These findings significantly expand the scope of chemical functionalities that can be utilized to design cooperative CO2 adsorbents, providing further means of optimizing these powerful materials for energy-efficient CO2 separations

    A Conceptual Model for Navigating a Career Path in Medical School Leadership

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    There is a paucity of literature providing guidance to physicians hoping to attain a position as a medical school dean. Realizing this gap, the Society for Academic Emergency Medicine (SAEM) Faculty Development Committee organized an educational session focused on offering faculty guidance for obtaining a position in medical school leadership. The session involved panelists who are nationally known leaders in medical school administration and was successfully presented at the SAEM 2018 annual meeting in Indianapolis, Indiana. Knowledge and perspective gained both during this session and through literature review was analyzed using a conceptual thinking skills framework. This process offered insights that promoted the development of a conceptual model informed by current evidence and expert insight and rooted in educational, economic, and cognitive theory. This model provides a step‐by‐step guide detailing a process that physicians can use to create a plan for professional development that is informed, thoughtful, and individualized to their own needs to optimize their future chances of advancing to a career in medical school leadership.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146843/1/aet210212.pd

    Water Enables Efficient CO2 Capture from Natural Gas Flue Emissions in an Oxidation-Resistant Diamine-Appended Metal-Organic Framework.

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    Supported by increasingly available reserves, natural gas is achieving greater adoption as a cleaner-burning alternative to coal in the power sector. As a result, carbon capture and sequestration from natural gas-fired power plants is an attractive strategy to mitigate global anthropogenic CO2 emissions. However, the separation of CO2 from other components in the flue streams of gas-fired power plants is particularly challenging due to the low CO2 partial pressure (∼40 mbar), which necessitates that candidate separation materials bind CO2 strongly at low partial pressures (≤4 mbar) to capture ≥90% of the emitted CO2. High partial pressures of O2 (120 mbar) and water (80 mbar) in these flue streams have also presented significant barriers to the deployment of new technologies for CO2 capture from gas-fired power plants. Here, we demonstrate that functionalization of the metal-organic framework Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) with the cyclic diamine 2-(aminomethyl)piperidine (2-ampd) produces an adsorbent that is capable of ≥90% CO2 capture from a humid natural gas flue emission stream, as confirmed by breakthrough measurements. This material captures CO2 by a cooperative mechanism that enables access to a large CO2 cycling capacity with a small temperature swing (2.4 mmol CO2/g with ΔT = 100 °C). Significantly, multicomponent adsorption experiments, infrared spectroscopy, magic angle spinning solid-state NMR spectroscopy, and van der Waals-corrected density functional theory studies suggest that water enhances CO2 capture in 2-ampd-Mg2(dobpdc) through hydrogen-bonding interactions with the carbamate groups of the ammonium carbamate chains formed upon CO2 adsorption, thereby increasing the thermodynamic driving force for CO2 binding. In light of the exceptional thermal and oxidative stability of 2-ampd-Mg2(dobpdc), its high CO2 adsorption capacity, and its high CO2 capture rate from a simulated natural gas flue emission stream, this material is one of the most promising adsorbents to date for this important separation

    Amine Dynamics in Diamine-Appended Mg2(dobpdc) Metal-Organic Frameworks.

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    Variable-temperature 15N solid-state NMR spectroscopy is used to uncover the dynamics of three diamines appended to the metal-organic framework Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate), an important family of CO2 capture materials. The results imply both bound and free amine nitrogen environments exist when diamines are coordinated to the framework open Mg2+ sites. There are rapid exchanges between two nitrogen environments for all three diamines, the rates and energetics of which are quantified by 15N solid-state NMR data and corroborated by density functional theory calculations and molecular dynamics simulations. The activation energy for the exchange provides a measure of the metal-amine bond strength. The unexpected negative correlation between the metal-amine bond strength and CO2 adsorption step pressure reveals that metal-amine bond strength is not the only important factor in determining the CO2 adsorption properties of diamine-appended Mg2(dobpdc) metal-organic frameworks

    Endoscopic, radiologic, and histologic healing with vedolizumab in patients with active Crohn's disease

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    BACKGROUND & AIMS: Vedolizumab is a gut-selective monoclonal antibody for the treatment of moderately to severely active Crohn's disease (CD). We performed a prospective study of endoscopic, radiologic, and histologic healing in patients with CD who received vedolizumab therapy. METHODS: We performed a phase 3b, open-label, single-group study of 101 patients with at least 3 months of active CD (a CD Activity Index [CDAI] score of 220-450, a simple endoscopic score for CD [SES-CD] of 7 or more, 1 or more mucosal ulcerations [identified by endoscopy], and failure of conventional therapy) from March 2015 through December 2017. Among the patients enrolled, 54.5% had previous failure of 1 or more tumor necrosis factor (TNF) antagonists and 44.6% had severe endoscopic disease activity (SES-CD scores above 15) at baseline. Participants received vedolizumab (300 mg intravenously) at weeks 0, 2, and 6, and then every 8 weeks thereafter, for 26 weeks (primary study) or 52 weeks (substudy, 56 patients). The primary endpoint at week 26 was endoscopic remission (SES-CD score of 4 or less); other endpoints included endoscopic response (50% reduction in SES-CD), radiologic remission (magnetic resonance index of activity score below 7), and histologic response (modified global histologic disease activity score of 4 or less). RESULTS: At week 26, 11.9% of patients were in endoscopic remission (95% confidence interval [CI] 6.3-9.8); at week 52, 17.9% of the patients were in endoscopic remission (95% CI 8.9-30.4). Higher proportions of patients naïve to TNF antagonists achieved endoscopic remission than patients with TNF-antagonist-failure at weeks 26 and 52. Higher proportion of patients with moderate CD (SES-CD scores, 7-15) achieved endoscopic remission at weeks 26 and 52 than patients with severe CD (SES-CD scores above 15). The proportion of patients with complete mucosal healing increased over time, with greater rates of healing in the colon than in the ileum. Remission was detected by magnetic resonance enterography in 21.9% of patients at week 26 (95% CI 9.3-40.0) and in 38.1% at week 52 (95% CI 18.1-61.6). At week 26, 24.4% of patients had a histologic response in the colon (95% CI 15.3-35.4) and 28.3% of patients had a histologic response in the ileum (95% CI 17.5-41.4). At week 52, 20.5% of patients had a histologic response in the colon (95% CI 9.8-35.3) and 34.3% of patients had a histologic response in the ileum (95% CI 19.1-52.2). There were no notable safety issues, including worsening of extraintestinal manifestations. CONCLUSIONS: In a phase 3b trial, we found that 26 and 52 weeks of treatment with vedolizumab (300 mg, at weeks 0, 2, and 6, and then every 8 weeks thereafter) induces endoscopic, radiologic, and histologic healing in patients with moderately to severely active CD. ClinicalTrials.gov no: NCT02425111. ispartof: GASTROENTEROLOGY vol:157 issue:4 pages:1007-+ ispartof: location:United States status: publishe

    The accuracy of the report of hepatic steatosis on ultrasonography in patients infected with hepatitis C in a clinical setting: A retrospective observational study

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    BACKGROUND: Steatosis is occasionally reported during screening ultrasonography in patients with hepatitis C virus (HCV). We conducted a retrospective observational study to assess the factors associated with steatosis on ultrasonography and the relationship between steatosis on ultrasound versus biopsy in patients infected with HCV in a clinical setting. Our hypothesis was ultrasonography would perform poorly for the detection of steatosis outside of the context of a controlled study, primarily due to false-positive results caused by hepatic fibrosis and inflammation. METHODS: A retrospective review of ultrasound reports was conducted on patients infected with HCV in a tertiary care gastroenterology clinic. Reports were reviewed for the specific documentation of the presence of steatosis. Baseline clinical and histologic parameters were recorded, and compared for patients with vs. without steatosis. Multiple logistic regression analysis was performed on these baseline variables. Liver biopsies were reviewed by two pathologists, and graded for steatosis. Steatosis on biopsy was compared to steatosis on ultrasound report, and the performance characteristics of ultrasonography were calculated, using biopsy as the gold standard. RESULTS: Ultrasound reports were available on 164 patients. Patients with steatosis on ultrasound had a higher incidence of the following parameters compared to patients without steatosis: diabetes (12/49 [24%] vs. 7/115 [6%], p < 0.001), fibrosis stage >2 (15/48 [31%] vs. 16/110 [15%], p = 0.02), histologic grade >2 (19/48 [40%] vs. 17/103 [17%], p = 0.002), and ALT (129.5 ± 89.0 IU/L vs. 94.3 ± 87.0 IU/L, p = 0.01). Histologic grade was the only factor independently associated with steatosis with multivariate analysis. When compared to the histologic diagnosis of steatosis (n = 122), ultrasonography had a substantial number of false-positive and false-negative results. In patients with a normal ultrasound, 8/82 (10%) had >30% steatosis on biopsy. Among patients with steatosis reported on ultrasound, only 12/40 (30%) had >30% steatosis on biopsy review. CONCLUSION: Steatosis on ultrasound is associated with markers of inflammation and fibrosis in HCV-infected patients, but does not consistently correlate with steatosis on biopsy outside of the context of a controlled study. Clinicians should be skeptical of the definitive diagnosis of steatosis on hepatic ultrasonography
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