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A 2D phospholipid crystal (dark) grows within a fluid vesicle membrane (light), starting as a small flower shape. While the area of the crystal grows progressively, the flower shape is preserved, a result of tension pre-conditioning.
A hydrophobic electroconductive LIG membrane with ∼143.7° water contact angle is prepared showing average surface temperature of ∼140 °C with 91 MHz radiofrequency heating. Vacuum membrane distillation shows ∼13.5 L m −2 h −1 flux.
Abstract Background To address the prognostic value of combining tubular basement membrane (TBM) and glomerular basement membrane (GBM) thickness in diabetic nephropathy (DN). Methods This retrospective study enrolled 110 patients with type 2 diabetes and biopsy‐proven DN from 2011 to 2018. The pathological findings were confirmed according to the Renal Pathology Society classifications. GBM and TBM thicknesses were determined using the Haas' direct measurement/arithmetic mean method and orthogonal intercept method, respectively. Cox proportional hazard models were used to investigate the hazard ratios (HRs) for the influence of combined GBM and TBM thickness for predicting end‐stage renal disease (ESRD). Results Patients were assigned to three groups according to the median GBM and TBM thickness: GBM lo TBM lo (GBM < 681 nm and TBM < 1200 nm), GBM hi TBM lo /GBM lo TBM hi (GBM ≥ 681 nm and TBM < 1200 nm, or GBM < 681 nm and TBM ≥ 1200 nm), and GBM hi TBM hi (GBM ≥ 681 nm and TBM ≥ 1200 nm). The GBM hi TBM lo /GBM lo TBM hi and GBM hi TBM hi groups displayed poorer renal function, a more severe glomerular classification and interstitial inflammation, and poorer renal survival rates than the GBM lo TBM lo group The GBM hi TBM lo /GBM lo TBM hi and GBM hi TBM hi groups had adjusted HRs of 1.49 (95% confidence interval [CI], 1.21‐9.75) and 3.07 (95% CI, 2.87‐12.78), respectively, compared with the GBM lo TBM lo group. Conclusions TBM thickness enhanced GBM thickness for renal prognosis in patients with type 2 diabetes.
Hydroxide exchange membrane fuel cells (HEMFCs) are a potentially lower-cost hydrogen fuel cell technology; however, ambient levels of CO 2 in air significantly reduce HEMFCs’ performance. In this work, we demonstrate an electrochemically-driven CO 2 separator (EDCS) which can be used to remove ambient levels of CO 2 from air upstream of the HEMFC stack in fuel cell vehicles, protecting it from CO 2 -related performance losses. The EDCS operating window was explored for current density, anode flow, and cathode flow with respect to its impact on CO 2 separation performance. Additionally, gas-phase mass transport was improved by selecting flow fields and gas diffusion layers conducive to the EDCS operating regime. The use of a carbon-ionomer interlayer at the cathode was explored and improved CO 2 removal performance from 77.7% to 98.2% at 20 mA cm −2 . An analytical, 1-D model is used to explain the experimental observations and design improvements. A single-cell, 25 cm 2 EDCS using the aforementioned improved design demonstrated greater than 98% CO 2 removal at a cathode flow rate of 1300 sccm for 100 h with 2.7% hydrogen stack consumption.
Fluxes of negatively charged, neutral, and positively charged vanadium acetylacetonates through the cation-exchange membrane Nafion® 211 were measured as functions of current density. Fluxes increase in order V(C 5 H 7 O 2 ) 3 – < V(C 5 H 7 O 2 ) 3 0 < V(C 5 H 7 O 2 ) 3 + as expected for a membrane with fixed negative charges. Furthermore, the dependence of these fluxes on current density is quantitatively consistent with predictions made using independently measured conductivities in Nernst-Planck-Einstein transport equations. However, differences between the three fluxes are smaller than predicted by Donnan equilibrium calculations for Nafion 211 immersed in V(C 5 H 7 O 2 ) 3 solutions. Furthermore, specific interactions between sorbed species appear to be responsible for the relatively rapid transport of V(C 5 H 7 O 2 ) 3 – compared to V(C 5 H 7 O 2 ) 3 + .
Oral presentation for ACS Spring Meeting
The primary function of the ionomers that are incorporated into fuel cell electrode catalyst layers is to provide pathways for ion transport between the catalyst active sites and the electrolyte. This is influenced by many variables, including the ion-exchange capacity, water uptake, and molecular weight. In anion exchange membrane fuel cells (AEMFCs), controlling ionomer water uptake is particularly important and tailoring this property in each electrode is an important consideration when looking to maximize cell performance. In this study, three poly(norbornene) tetrablock copolymer ionomers with a range of physical properties are synthesized and incorporated into AEMFC anode and cathode electrodes. Systematic electrode engineering with these ionomers allows the peak power density to be increased by 100% (1.6 W cm -2 → 3.2 W cm -2 ) and the current density at 0.2 V to be increased by 59% (5.9 A cm -2 → 9.4 A cm -2 ). Moreover, the top-performing electrode configuration is tested in an operating AEMFC at the US Department of Energy defined current density of 600 mA cm -2 for 2000 h, showing a record-low voltage decay rate of 15.36 µV h -1 – only 3.65% –a over 2000 h. Here, this work sets a new bar for AEMFCs, reporting the best combination of performance and durability of any AEMFC to date.
Advanced bipolar membranes (BPMs) with low water-dissociation overpotential (ηwd) may enable new electrochemical technologies for electrolysis, fuel cells, acid–base synthesis, brine remediation, lithium-battery recycling, and cement production. However, these advanced BPMs have only been demonstrated in BPM water electrolysis (BPMWE) configurations where the BPM is under static compression by the porous-transport layers. It is important to study these BPMs in applications like electrodialysis where large degrees of static compression are not possible. We present a BPM electrodialysis (BPMED) platform to measure water-dissociation overpotential (ηwd) and compare BPMWE and BPMED systems. We show advanced BPMs with half the ηwd compared to commercial BPMs for BPMED while maintaining ∼90% current efficiency from 0.05–0.5 A cm–2. The BPMED ηwd values are, however, about 0.2 V higher at 0.5 A cm–2 than those for BPMWE. Regardless, these results show that BPMs developed and optimized in BPMWE applications are well-suited for next-generation high-current-density BPMED technologies.
Here, to reduce the cost of fuel cell stacks and systems, it is important to create commercial catalysts that are free of platinum group metals (PGMs). To do this, such catalysts must have very high activity, but also have the correct microstructure to facilitate the transport of reactants and products. Here, we show a high-performing commercial oxygen reduction catalyst that was specifically developed for operation in alkaline media and is demonstrated in the cathode of operating anion-exchange membrane fuel cells (AEMFCs). With H 2 /O 2 reacting gases, AEMFCs made with Fe–N–C cathodes achieved a peak power density exceeding 2 W cm –2 (>1 W cm –2 with H 2 /air) and operated with very good voltage durability for more than 150 h. These AEMFCs also realized an iR-corrected current density at 0.9 V of 100 mA cm –2 . Finally, in a second configuration, Fe–N–C cathodes paired with low-loading PtRu/C anodes (0.125 mg PtRu per cm 2 , 0.08 mg Pt per cm 2 ) demonstrated a specific power of 10.4 W per mg PGM (16.25 W per mg Pt).
The structure of π-Ti 2 O(PO 4 ) 2 ·2H 2 O was determined by the SR-PXRD method. The proton conductivity of chitosan/π-TiP membranes reached 4.5 × 10 −3 S cm −1 at 95%-RH.
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Based on previous experimental evidence on isotopic substitution, we postulate that the hydronium radical (H3O·) might be present in PEMFCs. Our ab initio modeling indicates that this radical can be stabilized by the sulfonic anion on the polymer sidechain, leading to a greatly reduced reaction barrier in the t-F degradation reaction with the assistance of explicit water by undergoing a sidechain conformational change. To our knowledge, this is the first evidence that H3O· could be present in electrochemical devices with both experimental and theoretical support.
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