Formation of size-tunable CuI tetrahedra showing small band gap variation and high catalytic performance towards click reactions.

Tetrahedral CuI crystals with broadly tunable sizes from 56 to 645 nm have been synthesized by adjusting the reaction temperature, addition of different amounts of Na2SO4, or the reagent selection. The crystal growth process can be easily scaled up for catalysis applications. Bulk and surface compositions have been determined to be CuI using various characterization methods. Although larger tetrahedra show gradually decreasing band gap values, the changes are quite small. Optical facet effect should also be present for CuI by comparing the band gaps of size-tunable CuI tetrahedra to that of commercially available CuI powder. Emission band also becomes red-shifted for larger tetrahedral samples. The 56 nm CuI tetrahedra exhibit a far better catalytic performance than that of commercially available CuI powder toward click reactions of aromatic alkynes and benzyl azide for the formation of triazoles, attributed to their large surface area and exposed {111} faces. The small CuI tetrahedral nanocrystals should be explored for use in other CuI-catalyzed reactions.

Inference of chromosome-specific copy numbers using population haplotypes.

BACKGROUND: Using microarray and sequencing platforms, a large number of copy number variations (CNVs) have been identified in humans. In practice, because our human genome is a diploid, these platforms are limited to or more accurate for detecting total copy numbers rather than chromosome-specific copy numbers at each of the two homologous chromosomes. Nevertheless, the analysis of linkage disequilibrium (LD) between CNVs and SNPs indicates that distinct copy numbers often sit on their own background haplotypes. RESULTS: We propose new computational models for inferring chromosome-specific copy numbers by distinguishing background haplotypes of each copy number. The formulated problems are shown to be NP-hard and approximation/heuristic algorithms are developed. Simulation indicates that our method is accurate and outperforms the existing approach. By testing the program in 60 parent-offspring trios, the inferred chromosome-specific copy numbers are highly consistent with the law of Mendelian inheritance. The distributions of copy numbers at chromosomal level are provided for 270 individuals in three HapMap panels. CONCLUSIONS: The estimation of chromosome-specific copy numbers using microarray or sequencing platforms was often confounded by a number of factors. This study showed that the integration of background haplotypes is able to improve the accuracies of copy number estimation at chromosome level, especially for the CNVs having strong LD with SNPs in proximity.