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The article looks at a study related to the folliculitis decalvans (FD), a chronic primary disease, with the isolation of Staphylococcus aureus from primary lesions in untreated FD patients. Topics discussed include bacterial colonization of hair samples of FD patients, involvement of Propionibacterium acnes in the pathogenesis of FD and deeper parts of the hair follicle that was organized in biofilms.

A letter to the editor is presented in response to an article on genital graft-versus-host disease in a male after allogeneic stem cell transplantation.

Complementary studies of atom probe tomography, secondary ion mass spectrometry, and vertical current-voltage measurements are carried out in order to unravel the influence of C-doping of GaN on the vertical leakage current of AlN/AlGaN/GaN:C heterostructures. A systematic increment of the vertical blocking voltage at a given current density is observed in the structures, when moving from the nominally undoped conditions—corresponding to a residual C-background of ~1017cm-3—to a C-content of ~1019cm-3 in the GaN layer. The value of the vertical blocking voltage saturates for C concentrations higher than ~1019cm-3. Atom probe tomography confirms the homogeneity of the GaN:C layers, demonstrating that there is no clustering at C-concentrations as high as 1020cm-3. It is inferred that the vertical blocking voltage saturation is not likely to be related to C-clustering. [ABSTRACT FROM AUTHOR]

Capacitance-voltage [C(V)] measurements of metal-insulator-semiconductor-heterostructure capacitors are used to investigate the interface between silicon nitride passivation and AlGaN/AlN/GaN heterostructure material. AlGaN/AlN/GaN samples having different silicon nitride passivating layers, deposited using three different deposition techniques, are evaluated. Different interface state distributions result in large differences in the C(V) characteristics. A method to extract fixed charge as well as traps from the C(V) characteristics is presented. Rough estimates of the emission time constants of the traps can be extracted by careful analysis of the C(V) characteristics. The fixed charge is positive for all samples, with a density varying between 1.3×1012 and 7.1×1012 cm-2. For the traps, the peak density of interface states is varying between 16×1012 and 31×1012 cm-2 eV-1 for the three samples. It is concluded that, of the deposition methods investigated in this report, the low pressure chemical vapor deposited silicon nitride passivation shows the most promising results with regards to low densities of interface states. [ABSTRACT FROM AUTHOR]

AlGaN/AlN/GaN high electron mobility transistor heterostructures grown by metal-organic chemical vapor deposition have been studied by temperature dependent time-resolved photoluminescence. The AlGaN-related emission is found to be sensitive to the excitation power and to the built-in internal electric field. In addition, this emission shows a shift to higher energy with the reduction in the excitation density, which is rather unusual. Using a self-consistent calculation of the band potential profile, we suggest a recombination mechanism for the AlGaN-related emission involving electrons confined in the triangular AlGaN quantum well and holes weakly localized due to potential fluctuations. [ABSTRACT FROM AUTHOR]

The decoupling of epitaxial factors influencing the dynamic instabilities of AlGaN/GaN metal-insulator semiconductor high-electron-mobility transistors is investigated. Three different sets of samples have been analyzed by means of dynamic instabilities in the threshold voltage ( [ABSTRACT FROM AUTHOR]

Hidradenitis suppurativa (acne inverse) ( HS) is a chronic skin disease primarily affecting hair follicles. The aetiology of HS is unknown, but infection is believed to play some role. This retrospective study investigated the microbial colonization directly in skin appendices in HS skin samples. Archival samples from 27 patients with HS were screened by immunofluorescence labelling with monoclonal and polyclonal antibodies against Gram-positive bacteria, Propionibacterium acnes and Propionibacterium granulosum. Fluorescence in situ hybridization was used for further species identification of Staphylococcus spp. Overall, 17 patients (63%) were found positive for bacterial colonization. Of these, 15 showed colonization in hair follicles and/or sinus tracts. The most commonly identified bacteria were DAPI labelled coccoids that were seen in 71% of the positive patients in the form of biofilms and microcolonies. P. acnes was found as biofilms in hair follicles of two patients. Staphylococcus aureus and coagulase-negative staphylococci were not detected in any sample. The results of this study indicate a common bacterial presence in HS skin lesions. Bacterial biofilms are not uncommon and their pathogenic role needs further evaluation. [ABSTRACT FROM AUTHOR]

Abstract: Optical characterization of single quantum dots (QDs) by means of micro-photoluminescence (μPL) will be reviewed. Both QDs formed in the Stranski–Krastanov mode as well as dots in the apex of pyramidal structures will be presented. For InGaAs/GaAs dots, several excitonic features with different charge states will be demonstrated. By varying the magnitude of an external electric or magnetic field and/or the temperature, it has been demonstrated that the transportation of carriers is affected and accordingly the charge state of a single QD can be tuned. In addition, we have shown that the charge state of the QD can be controlled also by pure optical means, i.e. by altering the photo excitation conditions. Based on the experience of the developed InAs/GaAs QD system, similar methods have been applied on the InGaN/GaN QD system. The coupling of LO phonons to the QD emission is experimentally examined for both charged and neutral excitons in single InGaAs/GaAs QDs in the apex of pyramidal structures. It is shown that the positively charged exciton exhibits a significantly weaker LO phonon coupling in the μPL spectra than the neutral and negatively charged species, a fact, which is in consistency with model simulations performed. [Copyright &y& Elsevier]

Helicobacter pylori adherence in the human gastric mucosa involves specific bacterial adhesins and cognate host receptors. Here, we identify sialyl-dimeric-Lewis x glycosphingolipid as a receptor for H. pylori and show that H. pylori infection induced formation of sialyl-Lewis x antigens in gastric epithelium in humans and in a Rhesus monkey. The corresponding sialic acid-binding adhesin (SabA) was isolated with the “retagging” method, and the underlying sabA gene (JHP662/HP072S) was identified. The ability of many H. pylori strains to adhere to sialylated glycoconjugates expressed during chronic inflammation might thus contribute to virulence and the extraordinary chronicity of H. pylori infection. [ABSTRACT FROM AUTHOR]