FIB‐SEM and ToF‐SIMS Analysis of High‐Temperature PEM Fuel Cell Electrodes

The phosphoric acid (PA) distribution in the electrodes is a crucial factor for the performance of high-temperature polymer electrolyte fuel cells (HT-PEM FCs). Therefore, understanding and optimizing the electrolyte distribution is vital to maximizing power output and achieving low degradation. Although challenging, tracking the PA in nanometer-sized pores is essential because most active sites in the commonly used carbon black-supported catalysts are located in pores below 1 µm. For this study, a cell is operated at 200 mA cm−2 for 5 days. After this break-in period, the cathode is separated from the membrane electrode assembly and subsequently investigated by cryogenic focused ion beam scanning electron microscopy (cryo FIB-SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). PA is located on the surface and in the bulk of the cathode catalyst layer. In addition, the PA distribution can be successfully linked to the gas diffusion electrode morphology and the binder distribution. The PA preferably invades nanometer-sized pores and is uniformly distributed in the catalyst layer

Self-organized stable pacemakers near the onset of birhythmicity

General amplitude equations for reaction-diffusion systems near to the soft onset of birhythmicity described by a supercritical pitchfork-Hopf bifurcation are derived. Using these equations and applying singular perturbation theory, we show that stable autonomous pacemakers represent a generic kind of spatiotemporal patterns in such systems. This is verified by numerical simulations, which also show the existence of breathing and swinging pacemaker solutions. The drift of self-organized pacemakers in media with spatial parameter gradients is analytically and numerically investigated.Comment: 4 pages, 4 figure

Genome-Wide Association Study in BRCA1 Mutation Carriers Identifies Novel Loci Associated with Breast and Ovarian Cancer Risk

BRCA1-associated breast and ovarian cancer risks can be modified by common genetic variants. To identify further cancer risk-modifying loci, we performed a multi-stage GWAS of 11,705 BRCA1 carriers (of whom 5,920 were diagnosed with breast and 1,839 were diagnosed with ovarian cancer), with a further replication in an additional sample of 2,646 BRCA1 carriers. We identified a novel breast cancer risk modifier locus at 1q32 for BRCA1 carriers (rs2290854, P = 2.7×10-8, HR = 1.14, 95% CI: 1.09-1.20). In addition, we identified two novel ovarian cancer risk modifier loci: 17q21.31 (rs17631303, P = 1.4×10-8, HR = 1.27, 95% CI: 1.17-1.38) and 4q32.3 (rs4691139, P = 3.4×10-8, HR = 1.20, 95% CI: 1.17-1.38). The 4q32.3 locus was not associated with ovarian cancer risk in the general population or BRCA2 carriers, suggesting a BRCA1-specific associat

An improved soldering process for automotive radiators using induction heating

Abstract not availabl

FIB‐SEM and ToF‐SIMS Analysis of High‐Temperature PEM Fuel Cell Electrodes

Abstract The phosphoric acid (PA) distribution in the electrodes is a crucial factor for the performance of high‐temperature polymer electrolyte fuel cells (HT‐PEM FCs). Therefore, understanding and optimizing the electrolyte distribution is vital to maximizing power output and achieving low degradation. Although challenging, tracking the PA in nanometer‐sized pores is essential because most active sites in the commonly used carbon black‐supported catalysts are located in pores below 1 µm. For this study, a cell is operated at 200 mA cm−2 for 5 days. After this break‐in period, the cathode is separated from the membrane electrode assembly and subsequently investigated by cryogenic focused ion beam scanning electron microscopy (cryo FIB‐SEM) coupled with energy‐dispersive X‐ray spectroscopy (EDX) and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). PA is located on the surface and in the bulk of the cathode catalyst layer. In addition, the PA distribution can be successfully linked to the gas diffusion electrode morphology and the binder distribution. The PA preferably invades nanometer‐sized pores and is uniformly distributed in the catalyst layer

Using enhanced development tools offered by analytical Quality by Design to support switching of an analytical quality control method

Quality by Design (QbD) principles play an increasingly important role in pharmaceutical industry. Here, we used an analytical QbD (AQbD) approach to develop a capillary electrophoresis method under reducing conditions (rCE-SDS), with the aim of replacing SDS-PAGE as release and stability test method for a commercialized monoclonal antibody product. Method development started with defining analytical method performance requirements as part of an analytical target profile (ATP), followed by a systematic risk assessment of method input parameters and their relation to defined method outputs. Based on this, design of experiments (DoE) studies were performed to identify a method operable design region (MODR). The MODR could be leveraged to improve method robustness. In a bridging study, it was demonstrated that the rCE-SDS method is more sensitive than the legacy SDS-PAGE method, and a correlation factor could be established to compensate for an off-set due to the higher sensitivity, without losing the correlation to the historical data acquired with the former method. Overall, systematic application of AQbD principles for designing and developing a new analytical method helped to elucidate the complex dependency of method outputs on its input parameters. The link of the method to critical quality attributes and the definition of method performance requirements were found to be most relevant for de-risking the analytical method switch, regarding impact on the control strategy