Rokhlin actions and self-absorbing C*-algebras
Let A be a unital separable C∗-algebra, and D a K1-injective strongly selfabsorbing C∗-algebra. We show that if A is D-absorbing, then the crossed product of A by a compact second countable group or by Z or by R is D-absorbing as well, assuming the action satisfying a Rokhlin property. In the case of a compact Rokhlin action we prove a similar statement about approximate divisibility.
C_0(X)-algebras, stability and strongly self-absorbing C*-algebras
We study permanence properties of the classes of stable and so-called D-stable C*-algebras, respectively. More precisely, we show that a C_0(X)-algebra A is stable if all its fibres are, provided that the underlying compact metrizable space X has finite covering dimension or that the Cuntz semigroup of A is almost unperforated (a condition which is automatically satisfied for C*-algebras absorbing the Jiang--Su algebra Z tensorially). Furthermore, we prove that if D is a K_1-injective strongly self-absorbing C*-algebra, then A absorbs D tensorially if and only if all its fibres do, again provided that X is finite-dimensional. This latter statement generalizes results of Blanchard and Kirchberg. We also show that the condition on the dimension of X cannot be dropped. Along the way, we obtain a useful characterization of when a C*-algebra with weakly unperforated Cuntz semigroup is stable, which allows us to show that stability passes to extensions of Z-absorbing C*-algebras.
A Critical Assessment on Functional Attributes and Degradation Mechanism of Membrane Electrode Assembly Components in Direct Methanol Fuel Cells
Direct methanol fuel cells (DMFC) are typically a subset of polymer electrolyte membrane fuel cells (PEMFC) that possess benefits such as fuel flexibility, reduction in plant balance, and benign operation. Due to their benefits, DMFCs could play a substantial role in the future, specifically in replacing Li-ion batteries for portable and military applications. However, the critical concern with DMFCs is the degradation and inadequate reliability that affect the overall value chain and can potentially impede the commercialization of DMFCs. As a consequence, a reliability assessment can provide more insight into a DMFC component’s attributes. The membrane electrode assembly (MEA) is the integral component of the DMFC stack. A comprehensive understanding of its functional attributes and degradation mechanism plays a significant role in its commercialization. The methanol crossover through the membrane, carbon monoxide poisoning, high anode polarization by methanol oxidation, and operating parameters such as temperature, humidity, and others are significant contributions to MEA degradation. In addition, inadequate reliability of the MEA impacts the failure mechanism of DMFC, resulting in poor efficiency. Consequently, this paper provides a comprehensive assessment of several factors leading to the MEA degradation mechanism in order to develop a holistic understanding.