20 research outputs found
Five views of a secret: does cognition change during middle adulthood?
This study examined five aspects of change (or
stability) in cognitive abilities in middle adulthood across a
12-year period. Data come from the Interdisciplinary Study
on Adult Development. The sample consisted of N = 346
adults (43.8 years on average, 48.6% female). In total, 11
cognitive tests were administered to assess fluid and crystallized
intelligence, memory, and processing speed. In a
first series of analyses, strong measurement invariance was
established. Subsequently, structural stability, differential
stability, stability of divergence, absolute stability, and the
generality of changes were examined. Factor covariances
were shown to be equal across time, implying structural
stability. Stability coefficients were around .90 for fluid and
crystallized intelligence, and speed, indicating high, yet not
perfect differential stability. The coefficient for memory
was .58. Only in processing speed the variance increased
across time, indicating heterogeneity in interindividual
development. Significant mean-level changes emerged,
with an increase in crystallized intelligence and decline in
the other three abilities. A number of correlations among
changes in cognitive abilities were significant, implying
that cognitive change
An oxalate cathode for lithium ion batteries with combined cationic and polyanionic redox
Authors acknowledge financial support from the National Natural Science Foundation of China (51822210), the Australian Research Council (ARC) for its support through Discover Project (DP 140100193),Shenzhen Peacock Plan (KQJSCX20170331161244761), the Program for Guangdong Innovative and Entrepreneurial Teams (No. 2017ZT07C341), and the Development and Reform Commission of Shenzhen Municipality for the development of the “Low-Dimensional Materials and Devices” discipline.The growing demand for advanced lithium-ion batteries calls for the continued development of high-performance positive electrode materials. Polyoxyanion compounds are receiving considerable interest as alternative cathodes to conventional oxides due to their advantages in cost, safety and environmental friendliness. However, polyanionic cathodes reported so far rely heavily upon transition-metal redox reactions for lithium transfer. Here we show a polyanionic insertion material, Li2Fe(C2O4)2, in which in addition to iron redox activity, the oxalate group itself also shows redox behavior enabling reversible charge/discharge and high capacity without gas evolution. The current study gives oxalate a role as a family of cathode materials and suggests a direction for the identification and design of electrode materials with polyanionic frameworks.Publisher PDFPeer reviewe