Paul Chen

© 2015 Macmillan Publishers Limited. All rights reserved.A single molecular layer of titanium diselenide is a promising material for advanced electronics beyond graphene - a strong focus of current research. Such molecular layers are at the quantum limit of device miniaturization and can show enhanced electronic effects not realizable in thick films. We show that single-layer TiSe2 exhibits a charge density wave transition at critical temperature TC =232±5 K, which is higher than the bulk TC =200±5 K. Angle-resolved photoemission spectroscopy measurements reveal a small absolute bandgap at room temperature, which grows wider with decreasing temperature T below TC in conjunction with the emergence of ordering. The results are rationalized in terms of first-principles calculations, symmetry breaking and phonon entropy effects. The observed Bardeen-Cooper-Schrieffer behaviour of the gap implies a mean-field CDW order in the single layer and an anisotropic CDW order in the bulk.

© 2014 American Association for Cancer Research.Background: Identifying sources of variation in the nicotine and nitrosamine metabolic inactivation pathways is important to understanding the relationship between smoking and cancer risk. Numerous UGT1A and UGT2B enzymes are implicated in nicotine and nitrosamine metabolism in vitro; however, little is known about their roles in vivo. Methods: Within UGT1A1, UGT1A4, UGT1A9, UGT2B7, UGT2B10, and UGT2B17, 47 variants were genotyped, including UGT2B10∗2 and UGT2B17∗2. The association between variation in these UGTs and glucuronidation activity within European and African American current smokers, quantified as urinary ratios of the glucuronide over unconjugated compound for nicotine, cotinine, trans-30-hydroxycotinine, and 4--1--1-butanol, was investigated in regression models assuming a dominant effect of variant alleles. Results: Correcting for multiple testing, three UGT2B10 variants were associated with cotinine glucuronidation, rs2331559 and rs11726322 in European Americans and rs835309 in African Americans. Additional variants predominantly in UGT2B10 were nominally associated with nicotine and cotinine glucuronidation in both ethnicities in addition to UGT2B10∗2 in European Americans. UGT2B17∗2 in European Americans and UGT2B7 variants in African Americans were nominally associated with 3HC glucuronidation. UGT1A, UGT2B10, and UGT2B7 variants in African Americans were nominally associated with NNAL glucuronidation. Conclusions: Findings from this initial in vivo study support a role for multiple UGTs in the glucuronidation of tobacco-related compounds in vivo, in particular UGT2B10 and cotinine glucuronidation. Impact: Findings also provide insight into ethnic differences in glucuronidation activity, which could be contributing to ethnic disparities in the risk for smoking-related cancers.