Giant ambipolar Rashba effect in the semiconductor BiTeI

We observe a giant spin-orbit splitting in the bulk and surface states of the noncentrosymmetric semiconductor BiTeI. We show that the Fermi level can be placed in the valence or in the conduction band by controlling the surface termination. In both cases, it intersects spin-polarized bands, in the corresponding surface depletion and accumulation layers. The momentum splitting of these bands is not affected by adsorbate-induced changes in the surface potential. These findings demonstrate that two properties crucial for enabling semiconductor-based spin electronics-a large, robust spin splitting and ambipolar conduction-are present in this material.

Molecular profiling in patients (pts) with upper gastrointestinal (UGI) cancers correlated with clinical outcome

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Background: Recent efforts have expanded our understanding of the molecular pathogenesis of UGI cancers and how oncogenes and tumor suppressor genes play a role in both carcinogenic and metastatic processes. These markers may serve as prognostic and/or predictive factors for recurrence following resection and resistance to radiotherapy and chemotherapy. Gene expression levels of thymidylate synthase (TS), thymidylate phosphorylase (TP), epidermal growth factor receptor (EGFR) and excision repair cross complementing (ERCC-1) have been shown to be associated with outcomes in lung, gastric and colon cancer. We evaluated TS, ERCC-1, EGFR and TP gene expression levels in patients with UGI cancers. Methods: This was a retrospective study of 80 pts with UGI cancers evaluated at USC who underwent molecular profiling. The primary objective was to determine a correlation between TS, TP, ERCC1 and EGFR and correlate with clinical outcome. Characteristics of these 80 pts: (16 females, 64 males ); median age 61 years (range 34–85); tumor types evaluated - 32 (40%) esophageal, 24(30%) gastric, 24(30%) GE junction; stages- 53 % IV, 21% III, 12% II, 2% I were evaluated for intratumoral gene expression of TS, TP, ERCC-1, & EGFR by real time quantitative PCR using Taqman technology from microdisected paraffin-embedded tumor sections. Results: High TS expression was associated with shorter OS (12.8 months vs. 23.7 months p=0.036). A significant correlation was found between TP & ERCC-1 (p=0.0078, r=0.37); TP & TS (p=0.0128, r=0.35); TP & EGFR (p=0.0065, r=0.39); TS & ERCC-1 (p=0.0004, r=0.39); ERCC-1 & EGFR (p=0.025, r=0.30). No statistically significant relationship was found between TS & EGFR (p=0.06,r=0.25). There was no correlation of ERCC-1, TP, & EGFR with OS that reached statistical significance. Conclusions: TS mRNA levels were shown to be associated with OS in UGI tumors, consistent with data reported in colon cancer. TS gene expression was significantly associated with expression levels of ERCC-1. In addition, ERCC1 was associated with EGFR. These data show for the first time that molecular pathways of cytotoxic agents are linked to the EGFR pathway suggesting that sensitivity to fluoropyrimidines, oxaliplatin, and EGFR inhibitors may be associated.

No significant financial relationships to disclose.