Secondary ion mass spectrometry round-robin study for relative sensitivity factors in gallium arsenide

Round-robin studies on relative sensitivity factors (RSFs) in secondary ion mass spectrometry (SIMS) were conducted using bulk GaAs samples uniformly doped with various impurity elements. A total of 31 laboratories participated in two round-robins. More than 30 sets of relative ion intensities were obtained for B, Si, Cr, Mn, Fe, Cu, Zn, In and Te in GaAs. The RSFs for both positive and negative ions were derived for several types of SIMS instruments. The effect of primary ion incident angle was examined using quadrupole-based instruments and found to be the determining factor of the instrumental dependence of RSF

Management of primary cicatricial alopecias: Options for treatment

Primary cicatricial alopecias (PCAs) are a poorly understood group of disorders that result in permanent hair loss. Clinically, they are characterized not only by permanent loss of hair shafts but also of visible follicular ostia along with other visible changes in skin surface morphology, while their histopathological hallmark usually (although not always) is the replacement of follicular structures with scar-like fibrous tissue. As hair follicle neogenesis in adult human scalp skin is not yet a readily available treatment option for patients with cicatricial alopecias, the aim of treatment, currently, remains to reduce symptoms and to slow or stop PCA progression, namely the scarring process. Early treatment is the key to minimizing the extent of permanent alopecia. However, inconsistent terminology, poorly defined clinical end-points and a lack of good quality clinical trials have long made management of these conditions very challenging. As one important step towards improving the management of this under-investigated and under-serviced group of dermatoses, the current review presents evidence-based guidance for treatment, with identification of the strength of evidence, and a brief overview of clinical features of each condition. Wherever only insufficient evidence-based advice on PCA management can be given at present, this is indicated so as to highlight important gaps in our clinical knowledge that call for concerted efforts to close these in the near future.</p