Defects, strain relaxation, and compositional grading in high indium content InGaN epilayers grown by molecular beam epitaxy

We investigate the structural properties of a series of high alloy content InGaN epilayers grown by plasma-assisted molecular beam epitaxy, employing the deposition temperature as variable under invariant element fluxes. Using transmission electron microscopy methods, distinct strain relaxation modes were observed, depending on the indium content attained through temperature adjustment. At lower indium contents, strain relaxation by V-pit formation dominated, with concurrent formation of an indium-rich interfacial zone. With increasing indium content, this mechanism was gradually substituted by the introduction of a self-formed strained interfacial InGaN layer of lower indium content, as well as multiple intrinsic basal stacking faults and threading dislocations in the rest of the film. We show that this interfacial layer is not chemically abrupt and that major plastic strain relaxation through defect introduction commences upon reaching a critical indium concentration as a result of compositional pulling. Upon further increase of the indium content, this relaxation mode was again gradually succeeded by the increase in the density of misfit dislocations at the InGaN/GaN interface, leading eventually to the suppression of the strained InGaN layer and basal stacking faults

Methylene tetrahydrofolate reductase (MTHFR) gene polymorphisms among Greek women with medical history of recurrent pregnancy loss

Summarization: Regarding the article "Hereditary thrombophilia genetic variants in recurrent pregnancy loss" by Ahangari et al. about the association between hereditary thrombophilia genetic variants and recurrent miscarriage among Iranian women. In the present letter, unpublished relevant results from a study conducted among 383 Greek adults with low serum folate levels and main objective to investigate the necessity to determine homocysteine metabolism gene polymorphisms (MTHFR C677T and A1298C) in this population.Presented on

Mycobacterial species diversity at a general hospital on the island of Crete: First detection of Mycobacterium lentiflavum in Greece

The objective of the present study was to investigate the diversity of mycobacterial isolates in a general hospital in Crete, Greece. 48 positive Lowenstein-Jensen cultures over a 3-y period were analysed by means of AccuProbe and GenoType assays. Non-tuberculous mycobacteria (NTM) comprised the majority of the isolates (56.3%, 27/48) vs 33.3% (16/48) of M. tuberculosis; 10.4% of the isolates could not be classified. Among NTM, M. lentiflavum was the predominant species isolated (9/27) followed by M. kansasii, M. gordonae and M. peregrinum, whereas no M. avium complex isolates were detected. This is the first detection of M. lentiflavum in Greece. The susceptibilities of the M. lentiflavum isolates to an extended panel of antibiotics were determined by the proportions method and the medical files of the 9 patients were reviewed. Three isolates were from urine, which is an unusual site. All strains exhibited multidrug resistance. The patients were adults with immunosuppression or predisposing conditions for NTM infection. Diagnosis of true infection was either not pursued or the patients died shortly after isolation

Primary and secondary hyperparathyroidism among Vitamin D deficient Hashimoto's thyroiditis patients and the need for a parathyroid scan

Summarization: The patients with Hashimoto thyroiditis must be investigated mainly for secondary hyperparathyroidism due to vitamin D deficiency/insufficiency. Parathyroid scintigraphy has no place in the diagnosis of primary, secondary or tertiary hyperparathyroidism or in the decision for surgical treatment. Parathyroid scintigraphy is a useful preoperative technique for the localization of the pathological parathyroid glands.Παρουσιάστηκε στο: Hellenic Journal of Nuclear Medicin