Continuous stimulated emission at T=293 K from separate-confinement heterostructure diode lasers with one layer of InAs quantum dots grown on vicinal GaAs(bd001) surfaces misoriented in the [010] direction in the active region

The electroluminescence and stimulated emission of lasers with one layer of InAs quantum dots (QD’s) grown in a single molecular-beam epitaxial process on vicinal GaAs(001) surfaces misoriented in the direction [010] by 2, 4 and 6° are investigated. It is discovered that an increase in the misorientation angle leads to a blue shift and a decrease in the full width at half maximum (FWHM) of the electroluminescence spectrum. This effect is attributed to a decrease in the size of the quantum dots and improvement in their size uniformity. A strong dependence of the threshold current density on the width of the spontaneous luminescence spectrum is discovered. The room-temperature threshold current density of the lasers with one layer of quantum dots and the spontaneous luminescence spectrum having the smallest FWHM (54 meV) equals 210 A/cm². Fiz. Tekh. Poluprovodn. 32, 1482–1486 (December 1998)     

Silver dissolution on copper-based alloys

Electrical resistivity measurements and scanning electron microscopy was used to study the dissolution of silver on Cu-Ag and Cu-Al-Ag alloys. The results seem to indicate that the dissolution temperature is affected by the addition of aluminium.     

Giant cell myocarditis. Report of a case

The authors report a case of giant cell myocarditis leading to rapidly progressive cardiac failure despite immuno-suppressor treatment in a 20 year old woman. The cardiac failure was successfully managed by implantation of a left ventricular assist device and then cardiac transplantation. The problems encountered underline the importance of accurate diagnosis by endomyocardial biopsy before undertaking treatment and the difficulties in the choice of appropriate method of assistance in this indication. Giant cell myocarditis is a rare cause of cardiac failure and should be considered in the differential diagnosis in view of its clinical features and risk of progression. The literature and the therapeutic implications are discussed.     

Possible involvement of phosphatidylinositol 3-kinase in regulated exocytosis: studies in chromaffin cells with inhibitor LY294002

Several lines of evidence suggest that phosphorylated products of phosphatidylinositol play critical functions in the regulation of membrane trafficking along the secretory pathway. To probe the possible involvement of phosphatidylinositol 3-kinase (PI 3-kinase) in regulated exocytosis, we have examined its subcellular distribution in cultured chromaffin cells by immunoreplica analysis and confocal immunofluorescence. We found that the PI 3-kinase heterodimer consisting of the regulatory and catalytic subunits was associated essentially with the subplasmalemmal cytoskeleton in both resting and nicotine-stimulated chromaffin cells. Attempts to immunoprecipitate PI 3-kinase with anti-phosphotyrosine antibodies failed, suggesting that the activity of PI 3-kinase was not modulated by tyrosine phosphorylation and/or physical interaction with SH2-containing proteins in stimulated chromaffin cells. LY294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one], a potent inhibitor of PI 3-kinase, produced a dose-dependent inhibition of catecholamine secretion evoked by various secretagogues. Furthermore, cytochemical experiments with rhodamine-labeled phalloidin revealed that LY294002 blocked the disassembly of cortical actin in chromaffin cells stimulated by a depolarizing concentration of potassium. Our results suggest that PI 3-kinase may be one of the important regulatory exocytotic components involved in the signaling cascade controlling actin rearrangements required for catecholamine secretion.     

Oral malodor in dogs: measurement using a sulfide monitor

In 28 dogs, oral malodor was assessed organoleptically (0-3 scale) and by measurement of volatile sulfur components (VSC), using two positions ('intraoral' and 'tooth surface') for sampling VSC. Significant correlations were found between: intraoral and tooth surface VSC collection positions (p < 0.0001) and between organoleptic and tooth surface VSC data (p < 0.0001). VSC measurement is a sensitive, repeatable and non-subjective method of assessing oral malodor in dogs.     

Prospective study of carotid endarterectomy and contralateral carotid occlusion

A total of 700 patients who had carotid endarterectomy (CEA) in the UK and Ireland during a 6-month interval between March and August 1994 were studied prospectively. Some 108 patients (15.4 per cent) had a contralateral internal carotid artery occlusion. Previous reports have shown an associated stroke rate of about 10 per cent in these patients. This study assessed complications and outcome for patients undergoing CEA with contralateral internal carotid artery occlusion compared with those without. The indications for surgery were comparable between the two groups although the patients with occlusion had a slightly higher incidence of arrhythmia and stroke. Intraoperative shunts were used in a significantly higher proportion of those with occlusion (83.3 versus 64.7 per cent, P = 0.0001). The combined death and stroke rate for patients with occlusion was 5.6 per cent compared with 2.4 per cent for the remainder (P not significant). On the basis of the present data, CEA with a contralateral carotid artery occlusion carries only a slight increase in the rate of postoperative stroke and death. This increase was not statistically significant and is lower than that reported previously.