Total reflection of x-ray fluorescence (TXRF): a mature technique for environmental chemical nanoscale metrology

Total reflection x-ray fluorescence (TXRF) is a technique well established for chemical analysis of samples deposited as a thin layer. Nowadays it is mainly employed for electronic industry quality control. Recently, very compact and economic TXRF instrumentation was proposed. Combining this with the capability to analyze liquid samples, this technique is suitable to be employed in many different applications, comprising the very critical field of environmental analysis. Comparisons with the standard atomic absorption spectroscopy (AAS) technique show that TXRF is a practical, accurate, and reliable technique. Indeed, round-robin activities have already been started. Despite the efficiency and economy of the developed portable TXRF instrumentation, this is not widely employed for chemical laboratory analysis probably because TXRF is not an officially recognized technique, i.e. it is not yet normative-subjected. This fact could also be due to the long background of analytical applications developed for AAS, ICPS or inductively coupled plasma mass spectroscopy (ICP-MS) up to now. In this paper, we present a work of environmental monitoring of an industrial site, performed by means of bioindicators (lichens). The analysis of trace elements concentration in lichen was usually conducted with spectrophotometric techniques, such as AAS and ICP-MS, which were accepted by common regulations and normative-subjected. In this study, we accomplished a comparative lichen analysis by AAS and TXRF. The reproducibility of the obtained results showed the high correspondence between the two techniques. This comparison highlighted the versatility of the TXRF apparatus that allowed more rapid and simultaneous element detection. The obtained results suggested that this portable TXRF system could be suitable for regulation to produce certificated analysis upto ppb concentrations for some elements

The expression pattern of cytokeratin 6a in epithelial cells of different origin in dermo‐epidermal skin substitutes in vivo

Keratinocytes are the predominant cell type of skin epidermis. Through the programmed process of differentiation, they form a cornified envelope that provides a physical protective barrier against harmful external environment. Keratins are major structural proteins of keratinocytes that together with actin filaments and microtubules form the cytoskeleton of these cells. In this study, we examined the expression pattern and distribution of cytokeratin 6a (CK6a) in healthy human skin samples of different body locations, in fetal and scar skin samples, as well as in dermo‐epidermal skin substitutes. We observed that CK6a expression is significantly upregulated in fetal skin and scar tissue as well as in skin grafts after short‐term transplantation. Importantly, the abundance of CK6a corresponds directly to the expression pattern of wound healing marker CK16. We postulate that CK6a is a useful marker to accurately evaluate the homeostatic state of dermo‐epidermal skin substitutes.This article is protected by copyright