Bottom-Up Nanofabrication with Extreme-Ultraviolet Light: Metal-Organic Frameworks on Patterned Monolayers

The fabrication of integrated circuits with ever smaller (sub-10 nm) features poses fundamental challenges in chemistry and materials science. As smaller nanostructures are fabricated, thinner layers of materials are required, and surfaces and interfaces gain a more important role in the formation of nanopatterns. We present a new bottom-up approach in which we use the high optical resolution offered by extreme ultraviolet (EUV) lithography to print patterns on self-assembled monolayers (SAMs). Upon radiation, low-energy electrons induce chemical changes in the SAM so that the projected image is transferred to the substrate surface. We use the chemical differences between exposed and unexposed regions to promote a selective growth of hybrid structures that can act as an etch-resistant layer for further pattern transfer or can be used as functional nanostructures. The EUV doses required to promote selective growth on exposed areas are close to industrial requirements. Furthermore, this method allows for the independent tuning of different steps in the EUV lithography process (photo-induced chemistry, spatially resolved chemical contrast, and formation of nanopatterns), an advantage over current resists, in which the same material plays all roles.

Photoswitchable metal organic frameworks: turn on the lights and close the windows

Progress and challenges in the development of photo-responsive metal organic frameworks.

Significance of an atrial septal aneurysm in the presence of an ostium secundum atrial septal defect. A transesophageal echocardiographic study

The aim of this study was to elucidate the mechanism by which an atrial septal aneurysm is formed in the presence of an atrial septal defect by characterizing the distinguishing echocardiographic features of atrial septal defects between patients with and without an atrial septal aneurysm. The transesophageal echocardiograms of 30 consecutive patients who underwent surgical closure of a secundum atrial septal defect were compared with those of 8 normal controls. In patients with secundum atrial septal defect, the maximal diameter (mean +/- SD) of the fossa ovalis was 21.73 +/- 3.43 compared to 11.43 +/- 1.00 mm in the control group (p < 0.01). In the 7 (23%) patients with atrial septal aneurysm, the mean maximal diameter of the fossa ovalis was 25.28 +/- 3.03 compared to 20.65 +/- 2.78 mm in those without an atrial septal aneurysm (p < 0.01). The atrial septal defect was smaller in patients with than in those without an atrial septal aneurysm. In 4 patients with atrial septal aneurysm who had a history of a cerebrovascular event, the interatrial communication was only detected by contrast echocardiography. In conclusion, in patients with atrial septal aneurysm, atrial septal defects tend to be smaller but the incidence of cerebrovascular events is greater.

Contrast echocardiographic shunts may persist after atrial septal defect repair

We performed contrast echocardiography on 19 subjects who were asymptomatic in the postoperative period after surgical repair of atrial septal defects. Eighteen of these subjects had adequate right heart echocardiographic contrast to assess the presence or absence of right-to-left shunting. Multiple M-mode and two-dimensional echocardiographic views were studied during several contrast injections with and without the Valsalva manoeuvre. Six patients had postoperative shunts and 12 patients had no postoperative shunts. The age of the six patients with postoperative shunts was 26 +/- 10 years (mean +/- s.d.) and that of the 12 patients without postoperative shunts was 39 +/- 14 years. Four out of six of the postoperative shunt group were males and of these three had patch repairs compared with two males out of 12 with patch repair in the no shunt group. There were no definite differences between the two groups in the following variables: type of atrial septal defect (primum v. secundum), preoperative shunt size, pre-operative peak right ventricular pressure, pre-operative New York Heart Association functional class, pre- or postoperative right ventricular or left ventricular dimensions, aortic and left atrial dimensions. Four of the six patients with postoperative contrast echo shunting underwent cardiac catheterization, showing no significant step-up in oxygen saturation in three, and a significant shunt in one patient who had patch dehiscence at re-operation. We conclude that right-to-left shunts as demonstrated by contrast echocardiography are common in the late postoperative period after atrial septal defect repair. They need not indicate unsuccessful repair or a haemodynamically important residual shunt.

Noninvasive study of early diastole in mitral stenosis

Cardiac events of early diastole were studied in 50 normal subjects and 46 patients with mitral stenosis (MS) by simultaneous recordings of the mitral valve echogram (MVE), phonocardiogram, and apexcardiogram (ACG). Left ventricular isovolumic relaxation time (IRT), measured between A2 and onset of the MVE opening motion, had almost the same values in normals 54 +/- 7 msec, and MS 51 +/- 16 msec. The interval between A2 and the ACG "O" point was approximately double that of IRT: 99 +/- 11 msec in normal subjects, 109 +/- 20 msec in MS. The normal MVE opening motion had a velocity 293 +/- 76 mm/sec and duration 45 +/- 6 msec, values significantly different (P less than 0.001) from 536 +/- 271 mm/sec, 23 +/- 7.5 msec found in MS patients. In atrial fibrillation the length of the cardiac cycle did not affect A2-O interval or mitral valve opening movement duration; however cycle length was clearly related to isovolumic relaxation time. This resulted in a variation in the interval between completion of the mitral valve opening (opening snap) and O point. This interval was longer after a short diastole and vice versa.