Filtern
Dokumenttyp
Sprache
- Englisch (3)
Schlagworte
- Biomineralization (1)
- Carbonate precipitation (1)
- Decontamination (1)
- Granite (1)
- Hazardous substances (1)
- Laser cleaning (1)
- Laser imaging (1)
- Modelling (1)
- Moonmilk (1)
- Needle fibre calcite (1)
Organisationseinheit der BAM
- 6 Materialchemie (1)
- 6.3 Strukturanalytik (1)
The present study concerns the cleaning of matenats using pulsed laser irradiarton and it summarises the most recent results obtalned by the collaborative research of different European groups, within the kamework of a European program for tralnlng and mobillrv of researchers. A series of pulsed lasers, which emit at various wavelengths (liom UV to IR) wit11 short duration of pulse (few nano-, pico- or fernto-seconds), is used for the removal of metallic, ceramic and organic pollutants kom contaminated solid surfaces of different natures. The scientific results obtained so far are focused on the laser cleaning of silicon wafers from sub-micrometer particles, tile theoretical modelling of particles removal mechanism during dry laser cleaning, the removal of oxide layers from oxidised metals and alloys, as well as on the development of laser imaging as a diagnostrc tool for the estimation of the efficiency of the proposed cleaning technique.
Subsurface granitic environments are scarce and poorly investigated. A multi-disciplinary approach was used to characterize the abundant moonmilk deposits and associated microbial communities coating the granite walls of the 16th Century Paranhos spring water tunnel in Porto city (north-west Portugal). It is possible that this study is the first record of moonmilk in an urban subsurface granitic environment. The morphology and texture, mineralogical composition, stable isotope composition and microbial diversity of moonmilk deposits have been studied to infer the processes of moonmilk formation. These whitish secondary mineral deposits are composed of very fine needle fibre calcite crystals with different morphologies and density. Calcified filaments of fungal hyphae or bacteria were distinguished by field emission scanning electron microscopy. Stable isotope analysis revealed a meteoric origin of the needle fibre calcite, with an important contribution of atmospheric CO2, soil respiration and HCO3 − from weathering of Ca-bearing minerals. The DNA-based analyses revealed the presence of micro-organisms related to urban contamination, including Actinobacteria, mainly represented by Pseudonocardia hispaniensis, Thaumarchaeota and Ascomycota, dominated by Cladosporium. This microbial composition is consistent with groundwater pollution and contamination sources of the overlying urban area, including garages, petrol stations and wastewater pipeline leakage, showing that the Paranhos tunnel is greatly perturbed by anthropogenic activities. Whether the identified micro-organisms are involved in the formation of the needle fibre calcite or not is difficult to demonstrate, but this study evidenced both abiotic and biogenic genesis for the calcite moonmilk in this subsurface granitic environment.
Synchrotron radiation X-ray fluorescence spectroscopy, in conjunction with atomic absorption and Raman spectroscopy, was used to analyze a set of top brand tattoo inks to investigate the presence of toxic elements and hazardous substances. The Cr, Cu, and Pb contents were found to be above the maximum allowed levels established by the Council of Europe through the resolution ResAP(2008)1 on requirements and criteria for the safety of tattoos and permanent makeup. Raman analysis has revealed the presence of a set of prohibited substances mentioned in ResAP(2008)1, among which are the pigments Blue 15, Green 7, and Violet 23. Other pigments that were identified in white, black, red, and yellow inks are the Pigment White 6, Carbon Black, Pigment Red 8, and a diazo yellow, respectively. The present results show the importance of regulating tattoo ink composition.