skip to main content


Title: Thermal abiotic emission of CO 2 and CH 4 from leaf litter and its significance in a photodegradation assessment
NSF-PAR ID:
10102957
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Ecosphere
Volume:
10
Issue:
5
ISSN:
2150-8925
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. 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.

     
    more » « less
  2. Background

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

    Purpose

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

    Study Type

    Prospective.

    Population

    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.

    Assessment

    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.

    Results

    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

    2

    Technical Efficacy

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

     
    more » « less
  3. Abstract

    Nanoparticle (NP) additions can substantially improve the performance of reverse osmosis and nanofiltration polyamide (PA) membranes. However, the relative impacts of leading additives are poorly understood. In this study, we compare the effects ofTiO2andSiO2NPs as nanofillers in PA membranes with respect to permeate flux and the rejection of organic matter (OM) and salts. Thin‐film nanocomposite (TFN) PA membranes were fabricated using similarly sizedTiO215 nm andSiO2(10 – 20 nm)NPs, introduced at four different NP concentrations (0.01, 0.05, 0.2, and 0.5% w/v). Compared with PA membranes fabricated without NPs, membranes fabricated with nanofillers improved membranes hydrophilicity, membrane porosity, and consequently the permeability. Permeability was increased by 24 and 58% with the addition ofTiO2andSiO2, respectively. Rejection performance and fouling behavior of the membranes were examined with salt (MgSO4andNaCl) and OM (humic acid [HA] and tannic acid [TA]). The addition ofTiO2andSiO2nanofillers to the PA membranes improved the permeability of these membranes and also increased the rejection ofMgSO4, especially for TiO2membranes. The addition ofTiO2andSiO2to the membranes exhibited a higher flux and lower flux decline ratio than the control membrane in OM solution filtration. TFN membranes' HA and TA rejections were at least 77 and 71%, respectively. The surface change properties of NPs appear to play a dominant role in determining their effects as nanofillers in the composite membrane matrix through a balance of changes produced in membrane pore size and membrane hydrophilicity.

     
    more » « less