ABSTRACT
Dual-pulsed (DPL) laser deposition using oyster shells as targets was studied in order to find out if this method can replace the use of high-power pulsed lasers. Aspects related to changes in the morphological structure of the thin layer but also to the chemical composition of the obtained thin layer were analyzed and compared with the target as well as with the thin layers obtained with a higher power pulsed laser in a single-pulsed (SPL) regime. Orthorhombic structures were noticed with Scanning Electron Microscopy for the thin film obtained in DPL mode compared to the irregular particles obtained in SPL mode. The deacetylation process during ablation was evidenced by Fourier Transform Infrared spectroscopy, resulting in chitosan-based thin films. The effect of the obtained thin films of chitosan on the cells of baker's yeast (Saccharomyces cerevisiae) was studied. Restoration of the yeast paste into initial yeast was noticed mainly when the hemp fabric was used as support for the coating with yeas which was after that coated with chitosan thin film produced by DPL method.
ABSTRACT
The study in this paper was carried out as a result of the observation of pollution phenomena and foaming effects associated with anthropogenic activities, including street cleaning activity. The processes of dust binding used in order to reduce PM10 and PM 2.5 pollution has been proven to be inefficient, and even contributing to pollution with particulate matter. Our results suggest that the use of dust binders must be integrated in a technique that includes methods of removing agglomerated particle structures resulting from the process of coagulation or flocculation. These are the conclusions of the investigations carried out by spectroscopic methods (FTIR, SEM-EDX) on samples collected from the streets of Iasi on 10 March 2021, and on samples collected from the surface of the Precinct Wall of the historical monument Golia-Iasi Monastery Ensemble (Romania). On the later samples, coloristic analysis was also performed. The alert for investigation was given by the foaming waters that were leaking on the streets. The phenomenon was observed after the streets had been washed by specialized vehicles. Analyses revealed compounds used as dust binders and coagulant type (aluminum sulfate, sodium aluminate and their derivatives, plus anti-skid chemicals such as calcium chlorine and magnesium chlorine), as well as organic compounds included in aggregate type structures, and they showed contamination of the Golia Precinct Wall. The results show that the dust binders or coagulants used as such, or embedded in various products intended for the cleaning process of streets or other outdoor public places, must be subject to regulation. Otherwise, there is a risk of adding more pollutants during an operation with the opposite purpose. The migration of these pollutants on the studied building offers an image on how both our health and all constructions and equipment exposed in the open air are affected.
