Humidity and measurement of volatile propofol using MCC-IMS (EDMON)

The bedside Exhaled Drug MONitor – EDMON measures exhaled propofol in ppbv every minute based on multi-capillary column – ion mobility spectrometry (MCC-IMS). The MCC pre-separates gas samples, thereby reducing the infuence of the high humidity in human breath. However, preliminary analyses identifed substantial measurement deviations between dry and humid calibration standards. We therefore performed an analytical validation of the EDMON to evaluate the infuence of humidity on measurement performance. A calibration gas generator was used to generate gaseous propofol standards measured by an EDMON device to assess linearity, precision, carry-over, resolution, and the infuence of diferent levels of humidity at 100% and 1.7% (without additional) relative humidity (reference temperature: 37°C). EDMON measurements were roughly half the actual concentration without additional humidity and roughly halved again at 100% relative humidity. Standard concentrations and EDMON values correlated linearly at 100% relative humidity (R²=0.97). The measured values were stable over 100min with a variance≤10% in over 96% of the measurements. Carry-over efects were low with 5% at 100% relative humidity after 5min of equilibration. EDMON measurement resolution at 100% relative humidity was 0.4 and 0.6 ppbv for standard concentrations of 3 ppbv and 41 ppbv. The infuence of humidity on measurement performance was best described by a second-order polynomial function (R²≥0.99) with infuence reaching a maximum at about 70% relative humidity. We conclude that EDMON measurements are strongly infuenced by humidity and should therefore be corrected for sample humidity to obtain accurate estimates of exhaled propofol concentrations

Thermo-electrochemical production of compressed hydrogen from methane with near-zero energy loss

[EN] Conventional production of hydrogen requires large industrial plants to minimize energy losses and capital costs associated with steam reforming, water-gas shift, product separation and compression. Here we present a protonic membrane reformer (PMR) that produces high-purity hydrogen from steam methane reforming in a single-stage process with near-zero energy loss. We use a BaZrO3-based proton-conducting electrolyte deposited as a dense film on a porous Ni composite electrode with dual function as a reforming catalyst. At 800 degrees C, we achieve full methane conversion by removing 99% of the formed hydrogen, which is simultaneously compressed electrochemically up to 50 bar. A thermally balanced operation regime is achieved by coupling several thermo-chemical processes. Modelling of a small-scale (10 kg H-2 day-1) hydrogen plant reveals an overall energy efficiency of >87%. The results suggest that future declining electricity prices could make PMRs a competitive alternative for industrial-scale hydrogen plants integrating CO2 capture.This work was supported by the Research Council of Norway (grant 256264) and the Spanish Government (SEV-2016-0683 grant).Malerød-Fjeld, H.; Clark, D.; Yuste Tirados, I.; Zanón González, R.; Catalán-Martínez, D.; Beeaff, D.; Hernández Morejudo, S.... (2017). Thermo-electrochemical production of compressed hydrogen from methane with near-zero energy loss. Nature Energy. 2(12):923-931. https://doi.org/10.1038/s41560-017-0029-4S923931212Morejudo, S. H. et al. Direct conversion of methane to aromatics in a catalytic co-ionic membrane reactor. Science 353, 563–566 (2016).Chu, S. & Majumdar, A. Opportunities and challenges for a sustainable energy future. Nature 488, 294–303 (2012).Logan, B. E. & Elimelech, M. Membrane-based processes for sustainable power generation using water. Nature 488, 313–319 (2012).Rostrup-Nielsen, J. R. 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Mater. 14, 205–209 (2015).Myung, J.-h, Neagu, D., Miller, D. N. & Irvine, J. T. S. Switching on electrocatalytic activity in solid oxide cells. Nature 537, 528–531 (2016).Iwahara, H., Uchida, H., Ono, K. & Ogaki, K. Proton conduction in sintered oxides based on BaCeO3. J. Electrochem. Soc. 135, 529–533 (1988).Hamakawa, S., Hibino, T. & Iwahara, H. Electrochemical methane coupling using proton conductors. J. Electrochem. Soc. 140, 459–462 (1993).Bonanos, N., Knight, K. S. & Ellis, B. Perovskite solid electrolytes: structure, transport properties and fuel cell applications. Solid State Ion. 79, 161–170 (1995).Norby, T. Solid-state protonic conductors: principles, properties, progress and prospects. Solid State Ion. 125, 1–11 (1999).Kreuer, K. D. On the development of proton conducting materials for technological applications. Solid State Ion. 97, 1–15 (1997).Kreuer, K. D. Aspects of the formation and mobility of protonic charge carriers and the stability of perovskite-type oxides. Solid State Ion. 125, 285–302 (1999).Kreuer, K. D. Proton-conducting oxides. Annu. Rev. Mater. Res. 33, 333–359 (2003).Tao, S. W. & Irvine, J. T. S. A stable, easily sintered proton-conducting oxide electrolyte for moderate-temperature fuel cells and electrolyzers. Adv. Mater. 18, 11581-1584 (2006).Wang, H., Peng, R., Wu, X., Hu, J. & Xia, C. Sintering behavior and conductivity study of yttrium-doped BaCeO3–BaZrO3 solid solutions using ZnO additives. J. Am. Ceram. Soc. 92, 2623–2629 (2009).Coors, W. G. in Advances in Ceramics—Synthesis and Characterization, Processing and Specific Applications (Ed. Sikalidis, C.) Ch. 22, 501–520 (InTech, UK, 2011) (2011).Manabe, R. et al. Surface protonics promotes catalysis. Sci. Rep. 6, 38007, (2016).Rohland, B., Eberle, K., Ströbel, R., Scholta, J. & Garche, J. Electrochemical hydrogen compressor. Electrochimica Acta 43, 3841–3846 (1998).Kochetova, N., Animitsa, I., Medvedev, D., Demin, A. & Tsiakaras, P. Recent activity in the development of proton-conducting oxides for high-temperature applications. RSC Adv. 6, 73222–73268 (2016).Yamazaki, Y. et al. Proton trapping in yttrium-doped barium zirconate. Nat. Mater. 12, 647–651 (2013).Kjølseth, C. et al. Space-charge theory applied to the grain boundary impedance of proton conducting BaZr0.9Y0.1O3-δ . Solid State Ion. 181, 268–275 (2010).Coors, W. G A stoichiometric titration method for measuring galvanic hydrogen flux in ceramic hydrogen separation membranes. J. Membr. Sci. 458, 245–253 (2014).Zeppieri, M., Villa, P. L., Verdone, N., Scarsella, M. & De Filippis, P. Kinetic of methane steam reforming reaction over nickel- and rhodium-based catalysts. Appl. Catal. A 387, 147–154 (2010).Wang, B., Zhu, J. & Lin, Z. A theoretical framework for multiphysics modeling of methane fueled solid oxide fuel cell and analysis of low steam methane reforming kinetics. Appl. Energy 176, 1–11 (2016).Overview of Electricity Production and Use in Europe (European Environment Agency, 2016).Edwards, R., Larive, J.-F., Rickeard, D. & Weindorf, W. Well-To-Wheels Analysis of Future Automotive Fuels and Powertrains in the European Context, Well-to-Tank Report Version 4.a, JEC Well-to-Wheels Analysis (Joint Research Centre, 2014).Cho, V. H., Hamilton, B. A. & Kuehn, N. J. Assessment of Hydrogen Production with CO 2 Capture Volume 1: Baseline State-of-the-Art Plants (National Energy Technology Laboratory, 2010).Schjølberg, I. et al. Small-Scale Reformers for On-Site Hydrogen Supply (International Energy Agency-Hydrogen Implementing Agreement, 2012).de Visser, E. et al. Dynamis CO2 quality recommendations. Int. J. Greenhouse Gas Control 2, 478–484 (2008).Bertucciolo, L. et al. Development of Water Electrolysis in the European Union (Fuel Cells and Hydrogen Joint Undertaking, 2014).Edwards, R. et al. 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Morphology of supported polymer electrolyte ultra-thin films: a numerical study

Morphology of polymer electrolytes membranes (PEM), e.g., Nafion, inside PEM fuel cell catalyst layers has significant impact on the electrochemical activity and transport phenomena that determine cell performance. In those regions, Nafion can be found as an ultra-thin film, coating the catalyst and the catalyst support surfaces. The impact of the hydrophilic/hydrophobic character of these surfaces on the structural formation of the films has not been sufficiently explored yet. Here, we report about Molecular Dynamics simulation investigation of the substrate effects on the ionomer ultra-thin film morphology at different hydration levels. We use a mean-field-like model we introduced in previous publications for the interaction of the hydrated Nafion ionomer with a substrate, characterized by a tunable degree of hydrophilicity. We show that the affinity of the substrate with water plays a crucial role in the molecular rearrangement of the ionomer film, resulting in completely different morphologies. Detailed structural description in different regions of the film shows evidences of strongly heterogeneous behavior. A qualitative discussion of the implications of our observations on the PEMFC catalyst layer performance is finally proposed

A physical organogel electrolyte: Characterized by in situ thermo-irreversible gelation and single-ion-predominent conduction

Electrolytes are characterized by their ionic conductivity (??i). It is desirable that overall ??i results from the dominant contribution of the ions of interest (e.g. Li+ in lithium ion batteries or LIB). However, high values of cationic transference number (t+) achieved by solid or gel electrolytes have resulted in low ??i leading to inferior cell performances. Here we present an organogel polymer electrolyte characterized by a high liquid-electrolyte- level ??i (???101 mS cm-1) with high t+ of Li+ (>0.8) for LIB. A conventional liquid electrolyte in presence of a cyano resin was physically and irreversibly gelated at 60 ??C without any initiators and crosslinkers, showing the behavior of lower critical solution temperature. During gelation, ??i of the electrolyte followed a typical Arrhenius-type temperature dependency, even if its viscosity increased dramatically with temperature. Based on the Li + -driven ion conduction, LIB using the organogel electrolyte delivered significantly enhanced cyclability and thermal stability.open5

Molecular origin of enhanced proton conductivity in anhydrous ionic systems

YesIonic systems with enhanced proton conductivity are widely viewed as promising electrolytes in fuel cells and batteries. Nevertheless, a major challenge toward their commercial applications is determination of the factors controlling the fast proton hopping in anhydrous conditions. To address this issue, we have studied novel proton-conducting materials formed via a chemical reaction of lidocaine base with a series of acids characterized by a various number of proton-active sites. From ambient and high pressure experimental data, we have found that there are fundamental differences in the conducting properties of the examined salts. On the other hand, DFT calculations revealed that the internal proton hopping within the cation structure strongly affects the pathways of mobility of the charge carrier. These findings offer a fresh look on the Grotthuss-type mechanism in protic ionic glasses as well as provide new ideas for the design of anhydrous materials with exceptionally high proton conductivity

Influence of the Water Content on the Diffusion Coefficients of Li⁺ and Water across Naphthalenic Based Copolyimide Cation-Exchange Membranes

The transport of lithium ions in cation-exchange membranes based on sulfonated copolyimide membranes is reported. Diffusion coefficients of lithium are estimated as a function of the water content in membranes by using pulsed field gradient (PFG) NMR and electrical conductivity techniques. It is found that the lithium transport slightly decreases with the diminution of water for membranes with water content lying in the range 14 < λ < 26.5, where λ is the number of molecules of water per fixed sulfonate group. For λ < 14, the value of the diffusion coefficient of lithium experiences a sharp decay with the reduction of water in the membranes. The dependence of the diffusion of lithium on the humidity of the membranes calculated from conductivity data using Nernst–Planck type equations follows a trend similar to that observed by NMR. The possible explanation of the fact that the Haven ratio is higher than the unit is discussed. The diffusion of water estimated by 1H PFG-NMR in membranes neutralized with lithium decreases as λ decreases, but the drop is sharper in the region where the decrease of the diffusion of protons of water also undergoes considerable reduction. The diffusion of lithium ions computed by full molecular dynamics is similar to that estimated by NMR. However, for membranes with medium and low concentration of water, steady state conditions are not reached in the computations and the diffusion coefficients obtained by MD simulation techniques are overestimated. The curves depicting the variation of the diffusion coefficient of water estimated by NMR and full dynamics follow parallel trends, though the values of the diffusion coefficient in the latter case are somewhat higher. The WAXS diffractograms of fully hydrated membranes exhibit the ionomer peak at q = 2.8 nm⁻1, the peak being shifted to higher q as the water content of the membranes decreases. The diffractograms present additional peaks at higher q, common to wet and dry membranes, but the peaks are better resolved in the wet membranes. The ionomer peak is not detected in the diffractograms of dry membranes.The authors acknowledge financial support provided by the DGICYT (Dirección General de Investigación Cientifíca y Tecnológica) through Grant MAT2011-29174-C02-02