Dissociation of Single 2-Chloroanthracene Molecules by STM-Tip Electron Injection

We have studied the adsorption and tip-induced chemistry of 2-chloroanthracene on TiO₂(110). STM images show that at 135 K and low coverage, i.e., ∼0.1 ML, these molecules are physisorbed along the five-coordinated titanium rows on the rutile(110) surface as a result of electrostatic interaction. Applying electric pulses >2.5 V from the STM tip to individual molecules causes either desorption or dissociation of the molecules, as indicated by the changes in the STM images. We have observed dissociative electron capture of a single 2-chloroanthracene molecule, which leaves behind a surface chlorine atom adsorbed in the on-top configuration on a surface Ti atom. The threshold energy required for the dissociation was found to be ∼2.7 eV

Photoreactions on a Single Isolated TiO₂ Nanocrystal on Au(111): Photodecomposition of TMAA

An atomically resolved study of an adsorbate photoreaction on the surface of an isolated TiO₂ nanocrystal is reported. The crystal is grown <i>in situ</i> on Au(111) in an ultrahigh-vacuum chamber. The experiments use scanning tunneling microscopy (STM) backed by temperature-programmed desorption (TPD) to determine the surface coverage of trimethylacetic acid (TMAA) on the nanocrystal surfaces before and after irradiation with monochromated 305 nm UV light. A detailed determination of the surface structure of the 1–3 nm thick and 10–30 nm wide nanocrystals is presented and the importance of moiré effects in controlling the reaction sites shown. The normalized TMAA photodesorption quantum efficiency from Au-supported TiO₂ nanocrystals was found to be ∼4 times lower compared to the same reaction on rutile TiO₂(110) surface, a result consistent with the lower fraction of light adsorbed in the nanocrystals

Correlation of H Adsorption Energy and Nanoscale Elastic Surface Strain on Rutile TiO₂(110)

Scanning tunneling microscopy (STM) has been used to obtain the aerial distribution of bridge-bonded hydroxyl groups (HO_b) on a rutile TiO₂(110) surface, modified with a well-defined nanoscale strain field. Our study makes use of earlier findings that 5–30 nm wide locally strained areas of the surface can be formed via low-energy Ar-ion bombardment combined with a thermal treatment. These strained areas appear as protrusions in the STM images, resulting from subsurface argon-filled cavities. Our STM images show that the local surface concentration of OH_b groups is lower on the protrusions. This lowering of concentration has been interpreted as a reduction in the local H absorption energy, Δ<i>E</i>, a result similar to that observed on metals. In this paper, analysis of the reduction in this O–H bond energy across the surface shows a strong correlation between Δ<i>E</i>_OH and the characteristic surface strain value, <i>S</i>. The Δ<i>E</i>_OH values have been calculated through a subtraction of the contribution of the repulsive dipole–dipole interaction between OH_b groups. This interaction has been estimated from an analysis of the radial distribution of OH_b pairs in the STM images. The measured linear relation between the reduction in O–H bond energy and the surface strain has been estimated to be Δ<i>E</i>_OH (meV) ≈ 11·<i>S</i> (%)

Edoxaban versus warfarin in patients with atrial fibrillation

Contains fulltext : 125374.pdf (publisher's version ) (Open Access)BACKGROUND: Edoxaban is a direct oral factor Xa inhibitor with proven antithrombotic effects. The long-term efficacy and safety of edoxaban as compared with warfarin in patients with atrial fibrillation is not known. METHODS: We conducted a randomized, double-blind, double-dummy trial comparing two once-daily regimens of edoxaban with warfarin in 21,105 patients with moderate-to-high-risk atrial fibrillation (median follow-up, 2.8 years). The primary efficacy end point was stroke or systemic embolism. Each edoxaban regimen was tested for noninferiority to warfarin during the treatment period. The principal safety end point was major bleeding. RESULTS: The annualized rate of the primary end point during treatment was 1.50% with warfarin (median time in the therapeutic range, 68.4%), as compared with 1.18% with high-dose edoxaban (hazard ratio, 0.79; 97.5% confidence interval [CI], 0.63 to 0.99; P<0.001 for noninferiority) and 1.61% with low-dose edoxaban (hazard ratio, 1.07; 97.5% CI, 0.87 to 1.31; P=0.005 for noninferiority). In the intention-to-treat analysis, there was a trend favoring high-dose edoxaban versus warfarin (hazard ratio, 0.87; 97.5% CI, 0.73 to 1.04; P=0.08) and an unfavorable trend with low-dose edoxaban versus warfarin (hazard ratio, 1.13; 97.5% CI, 0.96 to 1.34; P=0.10). The annualized rate of major bleeding was 3.43% with warfarin versus 2.75% with high-dose edoxaban (hazard ratio, 0.80; 95% CI, 0.71 to 0.91; P<0.001) and 1.61% with low-dose edoxaban (hazard ratio, 0.47; 95% CI, 0.41 to 0.55; P<0.001). The corresponding annualized rates of death from cardiovascular causes were 3.17% versus 2.74% (hazard ratio, 0.86; 95% CI, 0.77 to 0.97; P=0.01), and 2.71% (hazard ratio, 0.85; 95% CI, 0.76 to 0.96; P=0.008), and the corresponding rates of the key secondary end point (a composite of stroke, systemic embolism, or death from cardiovascular causes) were 4.43% versus 3.85% (hazard ratio, 0.87; 95% CI, 0.78 to 0.96; P=0.005), and 4.23% (hazard ratio, 0.95; 95% CI, 0.86 to 1.05; P=0.32). CONCLUSIONS: Both once-daily regimens of edoxaban were noninferior to warfarin with respect to the prevention of stroke or systemic embolism and were associated with significantly lower rates of bleeding and death from cardiovascular causes. (Funded by Daiichi Sankyo Pharma Development; ENGAGE AF-TIMI 48 ClinicalTrials.gov number, NCT00781391.)