ABSTRACT
Structural disorder in molecular crystals is a fundamental limitation for achieving high charge carrier mobilities. Quantifying and uncovering the mechanistic origins of disorder are, however, extremely challenging. Here we use variable coherence transmission electron microscopy to analyze disorder in tri-isopropyl silane pentacene films, utilizing diffuse scattering that is present both as linear streaks and as a slowly varying, isotropic background. The former is due to thermal vibration of the pentacene molecules along their long axis, while the latter is due to static defects kinetically frozen during film deposition. The thermal vibrational amplitude is â¼0.4 Å, while the static displacement parameter in our simplified analysis is much larger (1.0 Å), because it represents the cumulative scattering of all defect configurations that are frozen in the film. Thin film fabrication therefore has an important effect on crystallinity; our technique can be readily used to compare samples prepared under different conditions.
ABSTRACT
Platelet reactivity (PR) and bleeding events following therapy with ticagrelor vs prasugrel have not been adequately studied. We aimed to compare PR and bleeding events in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) while on ticagrelor vs prasugrel for one month. Consecutive patients who were discharged either on ticagrelor 90 mg bid maintenance dose (MD) or prasugrel 10 mg MD were invited for PR assessment (VerifyNow, in PRU) at one month. High PR (HPR) was defined as >208 PRU. Bleeding events [Bleeding Academic Research Consortium (BARC) classification] were monitored. Out of 937 screened patients, 512 were analysed, 278 under ticagrelor MD and 234 under prasugrel MD. PR at 30 days (C-statistic of the propensity score model 0.63, 0.58-0.67 95% CI, p<0.001) was lower when on ticagrelor compared with prasugrel (33.3, 95% CI 29.3-37.3 vs 84.6, 95% CI 73.6-95.6, p<0.001). In the analysed population more BARC type 1 bleeding events were observed with ticagrelor compared to prasugrel (36.7% vs 28.2%, p=0.047). In 221 propensity score matched pairs, BARC type 1 bleeding rate was marginally higher in ticagrelor vs prasugrel treated patients (35.7% vs 27.1%, p=0.05). BARC type ≥2 events did not differ between groups 5 (2.3%) vs 5 (2.3%). HPR rate was higher for prasugrel-treated patients (5.4% vs 0%, p<0.001). In conclusion, in patients with ACS undergoing PCI, ticagrelor MD produces a significantly higher platelet inhibition compared to prasugrel MD. This pharmacodynamic difference might be associated with more nuisance bleeding events with ticagrelor use.
