The role of sulphur in the synthesis of carbon nanotubes by chemical vapour deposition at high temperatures.

Sulphur has been recognised as a growth promoter for carbon fibres and carbon nanotubes for over 30 years. Moreover, the Fe-C-S system, in particular, has been extensively studied for more than half a century in the fields of steelmaking and cast iron. In the present work we examine the role of sulphur in the iron-catalysed growth of carbon nanotubes during the process of direct spinning of fibres from the gas phase. A detailed microstructural characterisation of the reaction products was conducted by high resolution TEM and EELS composition mapping on a dedicated FEG STEM (VG HB 501) equipped with Cs aberration correctors. Our results agree with previous works in classical metallurgy, indicating that sulphur forms a layer on the surface of the catalyst particles that plays a role in encouraging nanotube growth by surface diffusion.

Apical hypertrophic cardiomyopathy: a study of 14 patients and their first degree relatives.

Although apical hypertrophic cardiomyopathy is generally accepted as a form of hypertrophic cardiomyopathy, its underlying genetic factors, clinical course and complications may be different. The characteristics of 14 Brazilian patients with a diagnosis of apical hypertrophic cardiomyopathy are described. Symptoms were frequent and abnormal filling of the left ventricle by Doppler criteria was recorded in all patients. Rest electrocardiograms showed giant negative T waves in 5 patients, all had low exercise capacity on an exercise stress test while significant arrhythmias were detected by 24-h ambulatory monitoring in just one patient. Forty-eight first degree relatives were studied and 3 had some form of hypertrophy of the left ventricle as seen by echocardiography. Apical hypertrophic cardiomyopathy in Brazilians seems to be expressed somewhat differently from that reported in Japanese patients, since "giant' T waves are less frequent and women more involved.

Quadricuspid aortic valve and aortic regurgitation diagnosed by Doppler echocardiography: report of two cases and review of the literature.

Two cases of patients with quadricuspid aortic valve diagnosed by Doppler echocardiography are presented. Aortic regurgitation was detected by pulsed Doppler echocardiography in both patients. Because they were young patients, this aortic regurgitation indicated that aortic regurgitation is not necessarily a late-developing event, as has been thought previously.