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Title: Modeling CO 2 emissions from A rctic lakes: Model development and site‐level study
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  
Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Journal of Advances in Modeling Earth Systems
Page Range / eLocation ID:
p. 2190-2213
Medium: X
Sponsoring Org:
National Science Foundation
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  2. Abstract

    Separation of higher hydrocarbons from methane is an important and energy‐intensive operation in natural gas processing. We present a detailed investigation of thin and oriented MFI zeolite membranes fabricated from 2D MFI nanosheets on inexpensive α‐alumina hollow fiber supports, particularly for separation ofn‐butane, propane, and ethane (“natural gas liquids”) from methane. These membranes display high permeances and selectivities for C2–C4hydrocarbons over methane, driven primarily by stronger adsorption of C2–C4hydrocarbons. We study the separation characteristics under unary, binary, ternary, and quaternary mixture conditions at 298 K and 100–900 kPa feed pressures. The membranes are highly effective in quaternary mixture separation at elevated feed pressures, for example allowingn‐butane/methane separation factors of 170–280 andn‐butane permeances of 710–2,700 GPU over the feed pressure range. We parametrize and apply multicomponent Maxwell–Stefan transport equations to predict the main trends in separation behavior over a range of operating conditions.

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  3. Background

    Cardiac MR fingerprinting (cMRF) is a novel technique for simultaneous T1and T2mapping.


    To compare T1/T2measurements, repeatability, and map quality between cMRF and standard mapping techniques in healthy subjects.

    Study Type



    In all, 58 subjects (ages 18–60).

    Field Strength/Sequence

    cMRF, modified Look–Locker inversion recovery (MOLLI), and T2‐prepared balanced steady‐state free precession (bSSFP) at 1.5T.


    T1/T2values were measured in 16 myocardial segments at apical, medial, and basal slice positions. Test–retest and intrareader repeatability were assessed for the medial slice. cMRF and conventional mapping sequences were compared using ordinal and two alternative forced choice (2AFC) ratings.

    Statistical Tests

    Pairedt‐tests, Bland–Altman analyses, intraclass correlation coefficient (ICC), linear regression, one‐way analysis of variance (ANOVA), and binomial tests.


    Average T1measurements were: basal 1007.4±96.5 msec (cMRF), 990.0±45.3 msec (MOLLI); medial 995.0±101.7 msec (cMRF), 995.6±59.7 msec (MOLLI); apical 1006.6±111.2 msec (cMRF); and 981.6±87.6 msec (MOLLI). Average T2measurements were: basal 40.9±7.0 msec (cMRF), 46.1±3.5 msec (bSSFP); medial 41.0±6.4 msec (cMRF), 47.4±4.1 msec (bSSFP); apical 43.5±6.7 msec (cMRF), 48.0±4.0 msec (bSSFP). A statistically significant bias (cMRF T1larger than MOLLI T1) was observed in basal (17.4 msec) and apical (25.0 msec) slices. For T2, a statistically significant bias (cMRF lower than bSSFP) was observed for basal (–5.2 msec), medial (–6.3 msec), and apical (–4.5 msec) slices. Precision was lower for cMRF—the average of the standard deviation measured within each slice was 102 msec for cMRF vs. 61 msec for MOLLI T1, and 6.4 msec for cMRF vs. 4.0 msec for bSSFP T2. cMRF and conventional techniques had similar test–retest repeatability as quantified by ICC (0.87 cMRF vs. 0.84 MOLLI for T1; 0.85 cMRF vs. 0.85 bSSFP for T2). In the ordinal image quality comparison, cMRF maps scored higher than conventional sequences for both T1(all five features) and T2(four features).

    Data Conclusion

    This work reports on myocardial T1/T2measurements in healthy subjects using cMRF and standard mapping sequences. cMRF had slightly lower precision, similar test–retest and intrareader repeatability, and higher scores for map quality.

    Evidence Level


    Technical Efficacy

    Stage 1 J. Magn. Reson. Imaging 2020;52:1044–1052.

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