High Capacity and Fast Kinetics Enabled by Metal-Doping in Prussian Blue Analogue Cathodes for Sodium-Ion Batteries.

Prussian blue analogues (PBAs) have gained tremendous attention as promising low-cost electrochemically-tunable electrode materials, which can accommodate large Na+ ions with attractive specific capacity and charge-discharge kinetics. However, poor cycling stability caused by lattice strain and volume change remains to be improved. Herein, metal-doping strategy has been demonstrated in FeNiHCF, Na1.40Fe0.90Ni0.10[Fe(CN)6]0.85 ⋅ 1.3H2O, delivering a capacity as high as 148 mAh g-1 at 10 mA g-1. At an exceptionally high rate of 25.6 A g-1, a reversible capacity of ~55 mAh g-1 still can be obtained with a very small capacity decay rate of 0.02 % per cycle for 1000 cycles, considered one of the best among all metal-doped PBAs. This exhibits the stabilizing effect of Ni doping which enhances structural stability and long-term cyclability. In situ synchrotron X-ray diffraction reveals an extremely small (~1 %) change in unit cell parameters. The Ni substitution is found to increase the electronic conductivity and redox activity, especially at the low-spin (LS) Fe center due to inductive effect. This larger capacity contribution from LS Fe2+C6/Fe3+C6 redox couple is responsible for stable high-rate capability of FeNiHCF. The insight gained in this work may pave the way for the design of other high-performance electrode materials for sustainable sodium-ion batteries.

A Synthesis of 20 Years of Research on Sexual Risk Taking Among Asian/Pacific Islander Men Who Have Sex With Men in Western Countries.

Over the past two decades, there has emerged a body of literature documenting a number of risk factors associated with Asian/Pacific Islander men who have sex with men's unsafe sexual behaviors. This study aims to systematically review existing empirical studies and synthesize research results into a social-ecological framework using a mixed research synthesis. Empirical research articles published in peer-reviewed journals between January 1990 and June 2013 were identified in six databases, including PubMed, Ovid MEDLINE, PsycINFO, Social Work Abstract, CINAL, and Web of Knowledge. Both quantitative and qualitative studies were included. Two analysts independently reviewed the articles, and findings were organized on a social-ecological framework. Twenty-two articles were included in the analysis; among these 13 were quantitative, 8 were qualitative, and 1 was mixed-methods research. Results indicated that demographic characteristics, psychological resources, behavioral patterns, relationships with family and friends, dynamics with romantic or sexual partners, community involvement, culture, discrimination, and institutional factors were related to unprotected anal intercourse. This article presents a critique of this literature and discusses implications for future research with this population. It concludes with prevention/intervention initiatives based on review findings.