Direct epitaxial growth of polar Hf0.5 Zr0.5 O2 films on corundum

Single-phase epitaxial Hf0.5 Zr0.5 O2 films with non-centrosymmetric orthorhombic structure have been grown directly on electrode-free corundum (a-Al2 O3) substrates by pulsed laser deposition. A combination of high-resolution X-ray diffraction and X-ray absorption spectroscopy confirms the epitaxial growth of high-quality films belonging to the Pca21 space group, with 111] out-of-plane orientation. The surface of a 7-nm-thick sample exhibits an atomic step-terrace structure with a corrugation of the order of one atomic layer, as proved by atomic force microscopy. Scanning transmission electron microscopy reveals that it consists of grains with around 10 nm lateral size. The polar nature of this film has been corroborated by pyroelectric measurements. These results shed light on the mechanisms of the epitaxial stabilization of the ferroelectric phase of hafnia. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

The College News, 1918-05-23, Vol. 04, No. 27

Bryn Mawr College student newspaper. Merged with The Haverford News in 1968 to form the Bi-college News (with various titles from 1968 on). Published weekly (except holidays) during the academic year

Endothelial dysfunction: potential clinical implications.

Vascular endothelium is responsible for the secretion of several substances exerting anti-atherogenic effects. Endothelial damage is also crucial for the progress of atherosclerosis and risk factors for atherosclerosis represent crucial factors associated with endothelial dysfunction. Studies have shown that patients with cardiovascular disease are characterized by impaired endothelial function (EF). Therefore, several agents have been proposed as potential modulators of EF. Most of the available approaches include pharmaceutical agents routinely used such as statins, angiotensin converting enzyme inhibitors, antioxidants, L-arginine, insulin sensitizers or others still under investigation such as tetrahydrobiopterin or folic acid (folate). Despite of the fact that there are several strategies aiming to improve endothelial dysfunction by enhancing nitric oxide bioavailability, it is still unclear whether they could be beneficial at a clinical level

Transthoracic Doppler echocardiography assessment of left anterior descending artery flow in patients with previous anterior myocardial infarction

Aim: We tested the hypothesis that shortening of diastolic pressure half time (PHT) of left anterior descending (LAD) coronary flow in patients with old reperfused anterior myocardial infarction (MI) is related to the presence of permanent myocardial damage of the reperfused area. Methods and results: We studied 49 patients divided into: group A: 15 patients with previous anterior MI and evidence of myocardial scar; group B: 10 patients with previous anterior MI and no evidence of myocardial scar and group C: 24 patients without anterior MI. All patients underwent coronary angiography at least 6 months after an index event and any reperfusion procedure. Group A patients had lower PHT (199 ± 62 ms) than group C (377 ± 103 ms, p = 0.0001) and group B (316 ± 154 ms, p = 0.029) patients. No other LAD flow velocity parameter differed among the 3 groups. A PHT value of 265 ms discriminated patients with scarred anteriorwallwith a sensitivity of 79% and a specificity of 94% (0.88, p < 0.001). Conclusion: Shortening of the LAD flow diastolic PHT in patients with remote, reperfused anterior MI reflects scarred myocardial tissue in the anteroapical wall while patients who maintain diastolic wall thickness after an acute coronary syndrome have PHT similar to patients without anterior MI