Two-dimensional quasistatic stationary short range surface plasmons in flat nanoprisms

We report on the nanometer scale spectral imaging of surface plasmons within individual silver triangular nanoprisms by electron energy loss spectroscopy and on related discrete dipole approximation simulations. A dependence of the energy and intensity of the three detected modes as function of the edge length is clearly identified both experimentally and with simulations. We show that for experimentally available prisms (edge lengths ca. 70 to 300 nm) the energies and intensities of the different modes show a monotonic dependence as function of the aspect ratio of the prisms. For shorter or longer prisms, deviations to this behavior are identified thanks to simulations. These modes have symmetric charge distribution and result from the strong coupling of the upper and lower triangular surfaces. They also form a standing wave in the in-plane direction and are identified as quasistatic short range surface plasmons of different orders as emphasized within a continuum dielectric model. This model explains in simple terms the measured and simulated energy and intensity changes as function of geometric parameters. By providing a unified vision of surface plasmons in platelets, such a model should be useful for engineering of the optical properties of metallic nanoplatelets.

Electronic and mechanical coupling of carbon nanotubes: a tunable resonant Raman study of systems with known structures

We report on the first tunable resonant Raman scattering study performed on suspended isolated and coupled single-wall carbon nanotubes, unambiguously identified by electron diffraction. Besides the confirmation of the relation between the structural properties, the radial breathing frequency and the optical resonances for isolated metallic nanotubes, we evidence that interacting nanotubes experience drastic modifications of their resonance fingerprints. We first demonstrate a degeneracy lifting of an electronic level in a bundle of identical zigzag nanotubes. We then show the existence of a strong energy transfer mediated by a mechanical coupling between two nonidentical bundled nanotubes.

Raman active phonons of identified semiconducting single-walled carbon nanotubes

The resonant Raman spectra of (n, m) semiconducting single-walled carbon nanotubes, unambiguously identified from their electron diffraction patterns, have been measured. The diameter dependence of the frequency of the tangential modes with A symmetry has been obtained in the diameter range from 1.4 to 2.5 nm. The comparison between the excitation energies and the calculated transition energies allowed us to determine precisely the values of the Es33 and Es44 transition energies. Finally, in the debate concerning the dominant process at the origin of the first-order Raman scattering in single-walled carbon nanotubes (single resonance process or double resonance process), our results are well understood in the framework of a single resonance process.

Bundles of identical double-walled carbon nanotubes

In a sample produced by catalytic chemical vapor deposition (CCVD), the structure of the carbon nanotubes (diameter and helicity) which governs their electronic properties, is determined by electron diffraction. We found that most of the smallest bundles are constituted of identical double-walled carbon nanotubes.

Experimental evidence of surface-plasmon coupling in anisotropic hollow nanoparticles

We report on the investigation of surface-plasmon excitation of anisotropic WS(2) hollow nanoparticles in a near-field geometry by means of a scanning transmission electron microscope. The shell thickness influence on the electron-energy-loss-spectroscopy spectra is experimentally observed and is analyzed within a classical dielectric formalism. As for the isotropic case, we evidence one symmetric (tangential) and one antisymmetric (radial) mode. We point out the intriguing fact that, for the anisotropic case, one can relate these modes to the interband transition of the in-plane component of the dielectric tensor and to the bulk-plasmon energy of the out-of-plane component.

13C NMR chemical shift of single-wall carbon nanotubes

We compute the magnetic shielding tensor within the London approximation and estimate the Knight shift of single-wall carbon nanotubes. Our results indicate that high resolution 13C NMR should be able to separate the metallic and insulator character of the nanotubes since a 11 ppm splitting is predicted from the respective resonances. As a model for disorder, bending, and defects in these structures, we investigate the magnetic response of nanotubes with finite size. We get a small line broadening coming from an intrinsic length dependent resonance effect. The nanotube packing is also studied and leads to a 20 ppm broadening which disappears under experimental high-resolution conditions.

Incidence, clinical significance and prognosis of ventricular fibrillation in the early phase of myocardial infarction

Of 1265 patients admitted to the CCU with the diagnosis of acute MI, 96 (7.6%) developed ventricular fibrillation within 72 hours following admission. Of these 96, 35 (36.5%) had secondary VF associated with left ventricular failure; they had a high in-hospital mortality of 57.1%. The remaining 61 (63.5%) had primary VF, i.e. VF occurring in the absence of significant LV failure. Fourteen of these (23%) died in hospital: 9 due to PVF (3 during the first episode, 6 during a recurrence). This mortality figure was significantly higher (P less than 0.001) than the mortality of 10% seen among patients who did not experience VF. Primary VF showed a recurrence rate of 20%. Compared with the 1061 patients who left the hospital without primary VF, the 61 subjects with this rhythm disorder were older, had larger infarcts and more frequent complications, such as pericarditis, conduction abnormalities, frequent ventricular premature contractions and signs of right ventricular failure. These findings, in contrast with a widely held view, suggest that primary VF may carry a guarded prognosis.

Incidence and significance of pericardial effusion in acute myocardial infarction as determined by two-dimensional echocardiography

To determine the incidence and clinical significance of pericardial effusion after acute myocardial infarction, two-dimensional echocardiography was serially performed in 66 consecutive patients. Pericardial effusion was observed in 17 (26%); the effusion was small in 13 patients, moderate in 3 and large with signs of cardiac tamponade in 1. In this patient, two-dimensional echocardiography strongly suggested myocardial rupture. The observation of pericardial effusion was not associated with age, sex, previous myocardial infarction, atrial fibrillation or treatment with heparin. It was more often a complication of anterior than of inferior acute infarction. Patients with pericardial effusion had higher peak levels of creatine kinase and lactic dehydrogenase and a higher wall motion score index. More patients with pericardial effusion had congestive heart failure or ventricular arrhythmias, developed a ventricular aneurysm or died within 1 year after their infarction. In conclusion, pericardial effusion is frequently visualized by two-dimensional echocardiography after acute myocardial infarction and its presence is associated with an increased occurrence of complications and cardiac death.

Frequency and clinical significance of pericardial friction rubs in the acute phase of myocardial infarction

An early pericardial friction rub was noted in 23.4% of a population of 1264 consecutive patients admitted with acute myocardial infarction. The incidence of the rub did not vary with age, sex or past cardiac history. The pericardial rub, however, was more often a complication of Q- than non-Q-wave infarcts (25.5% vs 10.5%, P greater than 0.001) and of anterior than inferior infarcts (35.3% vs 20.8%, P greater than 0.001). In comparing the 297 patients with a pericardial rub to the 967 others, we noted that the former group had a higher CK peak (1706 +/- 1110 UI l-1 vs 1189 +/- 1038 UI l-1, P greater than 0.001) and a higher incidence of Killip class greater than 1 (47.5% vs 33.2%, P greater than 0.001), atrial flutter or fibrillation (22.2% vs 9.3%, P greater than 0.001), second or third degree atrioventricular blocks (16.8% vs 9.4%, P greater than 0.001) and complete bundle branch block (14.5% vs 7.1%, P greater than 0.001). In spite of this, the development of a pericardial rub did not increase the in-hospital mortality (10.8% in patients with pericardial rub; 11.3% in those without).

Persistent atrial standstill in familial Ebstein's anomaly

Persistent atrial standstill occurred in a father and his youngest son with familial Ebstein's anomaly. In both cases routine electrocardiograms showed no atrial electrical activity and cross sectional echocardiograms showed inferior displacement of the septal tricuspid leaflet and tethering of the tricuspid leaflets to the right ventricle. The father had a cerebral embolism and died of a myocardial infarction. Necropsy showed attachment of the septal tricuspid leaflet below the membranous septum. On serial histological examination fibrofatty infiltration of the right atrial wall, the atrioventricular node, and the inferior part of the His bundle up to the bifurcation was present. The son had haemodynamic and electrophysiological findings consistent with mild Ebstein's anomaly and persistent atrial standstill, for which permanent cardiac pacing was necessary. The persistent atrial standstill with slow escape rhythm was most probably a consequence of the abnormalities in both the atrial wall and the His bundle which, together with the abnormal attachment of the tricuspid valve, may be features of the same congenital cardiac anomaly.

Pulmonary lymphangiomyomatosis

Pulmonary lymphangiomyomatosis is a rare disease of smooth muscle proliferation in the walls of lymphatic vessels and in the interstitial areas of the lungs. It only affects women of reproductive age. The majority of patients die from respiratory failure within 10 years. A new observation of pulmonary lymphangiomyomatosis is reported in a woman of 36 years. The disease was discovered at an advanced stage of respiratory failure. Left-sided pleurectomy and treatment with medroxy-progesterone and tamoxifen did not improve the patient's condition.

Patients with myocardial infarction and normal coronary arteriogram

Eighteen patients who survived an acute myocardial infarction were found to have a normal coronary arteriogram. Seven patients were younger than 35 years and six were female. The myocardial infarction was nontransmural in 11 cases. The mean follow-up was 21.6 months. Eleven patients developed residual chest pain at rest early after myocardial infarction. One, treated by beta-blockers, suffered a recurrent myocardial infarction. Eight became asymptomatic, and two improved under antispastic therapy. Another patient developed a severe form of variant angina three months after myocardial infarction; she died following plexectomy. Finally, two patients experienced rare episodes of angina at rest. The stress ECG was negative in all cases. Provocative test for spasm was positive in three out of nine patients. Diffuse narrowing associated with chest pain was demostrated in two patients at angiography. Thus, myocardial infarction and subsequent normal coronary angiogram are mainly found in young female patients, and infarction is often nontransmural. Clinical evidence of vasospastic phenomena and increased vasomotor tone are found in most patients. Whenever residual chest pain is controlled by antispastic therapy, the follow-up course seems benign.

[Treatment of Prinzmetal's angina with normal coronary vessels by thoracic sympathectomy]

Two cases of Prinzmetal angina with normal coronary arteries are reported: coronary spasm was demonstrated in the left anterior descending artery in the first, and in the right coronary artery in the second case. Invalidating angina persisted despite maximal medical treatment with nitrite derivatives, nifedipine, verapamil and amiodarone. Homolateral thoracic sympathectomy led to long term remission of symptoms in one case and a short remission in the other, who then had to undergo complete denervation by plexectomy. Two hours after reoperation a refractory spasm of the right coronary artery led to the death of the patient. The possible causes of refractory coronary spasm and possible therapeutic approaches are discussed with reference to these cases.

Pharmacokinetics of mexiletine in renal insufficiency

1 The aim of this study was to evaluate the influence of renal insufficiency on the plasma pharmacokinetics of mexiletine, a new antiarrhythmic agent, in human beings. 2 Mexiletine was administered orally three times daily for 10 days to 15 patients with chronic renal failure (creatinine clearance lower than 30 ml/min) and to 9 subjects with normal renal function. 3 The use of low doses of mexiletine was possible owing to the development of a new fluorescence h.p.l.c. method with a limit of sensitivity lower than 20 gn/ml. 4 Our results clearly indicate that the plasma kinetics of mexiletine are not modified when the renal clearance of creatinine is higher than 10 ml/min.

[Myocardial infarction and late pericarditis]

The post-infarction syndrome was observed in 8 out of 138 consecutive patients with acute myocardial infarction; 24 other cases of the post-infarction syndrome diagnosed over the preceeding 3 years were also reviewed. In order to determine the clinical significance and the prognosis, this group of 32 was compared to another of 105 patients with myocardial infarction without pericarditis, with respect to age, sex, medical history and characteristics of the underlying necrosis (location and size). Several clinical signs are discussed. This study showed the post-infarction syndrome was associated with large infarcts, the course of which was marked by arrhythmias, conduction defects and haemodynamic problems. A considerable inflammatory syndrome was often observed. The relation between the post-infarction syndrome and early pericarditis is not proved; on the other hand, a close correlation between late pericarditis, atrial fibrillation and left pleural effusion was demonstrated. The long term prognosis of infarcts complicated by the post-infarction syndrome is without doubt determined by the size of the necrosis and by the presence of ventricular aneurysms which are frequently associated.