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Abstract.A series of cluster anions C,~X-are produced from laser ablation of appropriate samples, where X is selected as a group-VB element. The recorded mass spectra of these cluster anions display a drastic even/odd alternation on ion intensities: For CnN-, only anions with odd n can be observed; For C~P-and C~As-, cluster anions with even n are produced but with lower signal intensities; For C~Sb-, the signal intensity of clusters does not show even/odd alternation; Finally, for CnBi-, the intensities of cluster anions with even n are higher than those with odd n. This parity effect can be attributed to the linear structure of the cluster anions, and the parity reversal of C~X-from C , N -to C~Bi-can be explained from the electronegativity decreasing of the heteroatom X as it descends in the group. The Hfickel model was applied to account the structural feature of these clusters.

This article reviews research on peer feedback in second language (L2) writing published in the last decade (i.e. 2005–2014). We analyse first the theoretical underpinnings that have informed both peer feedback research and the pedagogical use of peer feedback in L2 writing instruction. We also provide a critical interpretation of existing peer feedback research and discuss seven important themes emerging from the literature, that is, (1) effectiveness of peer feedback compared with teacher and self-feedback; (2) benefits of peer feedback for feedback-givers; (3) computer-mediated peer feedback; (4) peer feedback training; (5) student stances and motives; (6) peer interaction and group dynamics; and (7) cultural issues in peer feedback. Next, we examine the contextual and methodological issues in peer feedback research and then conclude the article with implications for future research.

In the last decade, there has been growing interest in professional learning communities (PLCs) outside mainstream Western contexts. In this paper, we provide a narrative synthesis of empirical studies of PLCs in kindergarten to 12th grade educational systems in mainland China published between 2006 and 2015. The review reveals five major emerging themes in the published literature: PLC characteristics; PLC practices in different regions; teacher collaboration in PLCs; the roles of university researchers; and educational leadership in PLCs. Significant progress has been identified in the enhancement of social harmony in teaching research groups, structural teacher collaboration, the construction of transregional PLCs and the complex roles of university researchers and school leaders. However, compared with the literature on PLCs in Western contexts, research on these communities in mainland China is still far from mature. The authors highlight the need for more empirically solid research on the development of sustainable PLCs in mainland China.

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