Rich Chemistry in Inorganic Halide Perovskite Nanostructures.

Halide perovskites have emerged as a class of promising semiconductor materials owing to their remarkable optoelectronic properties exhibiting in solar cells, light-emitting diodes, semiconductor lasers, etc. Inorganic halide perovskites are attracting increasing attention because of the higher stability toward moisture, light, and heat as compared with their organic-inorganic hybrid counterparts. In particular, inorganic halide perovskite nanomaterials provide controllable morphology, tunable optoelectronic properties, and improved quantum efficiency. Here, the development controlled synthesis of desired inorganic halide perovskite nanostructures by various chemical approaches is described. Utilizing these nanostructures as platforms, anion exchange chemistry for wide compositional and optical tunabilities is described, and the rich structural phase transition phenomenon and mechanism investigated systematically. Furthermore, these nanostructures and extracted knowledge are applied to design photonic, photovoltaic, and thermoelectric devices. Finally, future directions and challenges toward improvement of the optical, electrical, and optoelectronic properties, exploration of the anion and cation exchange kinetics, and alleviation of the stability and toxicity issues in inorganic lead based halide perovskites are discussed to provide an outlook on this promising field

The k-junction motif in RNA structure

The k-junction is a structural motif in RNA comprising a three-way helical junction based upon kink turn (k-turn) architecture. A computer program written to examine relative helical orientation identified the three-way junction of the Arabidopsis TPP riboswitch as an elaborated k-turn. The Escherichia coli TPP riboswitch contains a related k-junction, and analysis of >11 000 sequences shows that the structure is common to these riboswitches. The k-junction exhibits all the key features of an N1-class k-turn, including the standard cross-strand hydrogen bonds. The third helix of the junction is coaxially aligned with the C (canonical) helix, while the k-turn loop forms the turn into the NC (non-canonical) helix. Analysis of ligand binding by ITC and global folding by gel electrophoresis demonstrates the importance of the k-turn nucleotides. Clearly the basic elements of k-turn structure are structurally well suited to generate a three-way helical junction, retaining all the key features and interactions of the k-turn

Strategies-based Chinese as a Second Language Reading Instruction: Effects and Learners’ Perceptions

Strategic reading is an important consideration in the L2 reading classroom. This study investigated the effects of a Chinese as a Second Language (CSL) strategies-based reading instruction program, in which participants were explicitly taught ten top-down reading strategies. Thirty-four students enrolled in an advanced-level Chinese class participated in this study and were randomly assigned to treatment and control conditions. This study first examined the influence of the strategies-based instruction on participants’ reading comprehension. It then studied participants’ perceptions of using reading strategies and of the strategy training program. A series of non-parametric Mann-Whitney U tests showed that the experimental group made significantly greater improvement in overall reading comprehension and in answering global-reference questions. The survey results revealed that although participants generally confirmed the positive effects of reading strategies, they did not have a strong interest in learning reading strategies, or in applying them in L1 or L2 reading contexts

Antecedents of User Stickiness and Loyalty and Their Effects on Users’ Group-Buying Repurchase Intention

Intense competition among a vast number of group-buying websites leads to higher product homogeneity, which allows customers to switch to alternative websites easily and reduce their website stickiness and loyalty. This study explores the antecedents of user stickiness and loyalty and their effects on consumers’ group-buying repurchase intention. Results indicate that systems quality, information quality, service quality, and alternative system quality each has a positive relationship with user loyalty through user stickiness. Meanwhile, information quality directly impacts user loyalty. Thereafter, user stickiness and loyalty each has a positive relationship with consumers’ repurchase intention. Theoretical and managerial implications are also discussed