Screening of Satureja subspicata Vis. honey by HPLC-DAD, GC-FID/MS and UV/VIS: prephenate derivatives as biomarkers

The samples of Satureja subspicata Vis. honey were confirmed to be unifloral by melissopalynological analysis with the characteristic pollen share from 36% to 71%. Bioprospecting of the samples was performed by HPLC-DAD, GC-FID/MS, and UV/VIS. Prephenate derivatives were shown to be dominant by the HPLC-DAD analysis, particularly phenylalanine (167.8 mg/kg) and methyl syringate (MSYR, 114.1 mg/kg), followed by tyrosine and benzoic acid. Higher amounts of MSYR (3-4 times) can be pointed out for distinguishing S. subspicata Vis. honey from other Satureja spp. honey types. GC-FID/MS analysis of ultrasonic solvent extracts of the samples revealed MSYR (46.68%, solvent pentane/Et2O 1:2 (v/v); 52.98%, solvent CH2Cl2) and minor abundance of other volatile prephenate derivatives, as well as higher aliphatic compounds characteristic of the comb environment. Two combined extracts (according to the solvents) of all samples were evaluated for their antioxidant properties by FRAP and DPPH assay; the combined extracts demonstrated higher activity (at lower concentrations) in comparison with the average honey sample. UV/VIS analysis of the samples was applied for determination of CIE Lab colour coordinates, total phenolics (425.38 mg GAE/kg), and antioxidant properties (4.26 mmol Fe2+/kg (FRAP assay) and 0.8 mmol TEAC/kg (DDPH assay)

Picosecond pulsed laser ablation of silicon single crystal

Silicon-based nanoparticles (SiNPs) attract authors’ attention due its application prospects in a mutual field, from energy storage to bio-imaging. One of the most prominent methods for synthesis of SiNPs is pulsed laser ablation in liquid media (LAL), because it is simple, and it provides the minimum of contamination of the sample produced. Employed pulsed lasers in LAL are ns- and ps-, and the usage of fs- lasers are reported recently, as well. The objects of the LAL analyses are ablated craters on the Si target surface and, predominantly, the ablated material. Here, SiNPs are synthesized by ps- laser (150 ps, 1064 nm) ablation of Si single-crystal plates in de-ionized water. The focus of the work is the impact of the additional continuous wave (CW) laser (532nm) on the properties of the ablated material, i.e. SiNPs produced. The comprehensive analyses were performed, including the SiNPs’ size distribution, agglomeration abilities, aging, chemical properties (amount of oxygen and its distribution within the particles), and photoluminescence (PL) properties of the solution produced. It is demonstrated that PL properties of obtained SiNPs solution are impacted by introducing the CW laser in the ablation process. The peculiarity lies in the fact that such impact depends on both the PL excitation wavelength and the power of the introduced CW laser, which might open the possibility of successful tailoring of SiNPs produced by LAL.SPIG 2022 : 31st Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers and abstracts of invited lectures, topical invited lectures and progress reports; September 5-9,2022, Belgrad

Effect of antifouling paints and nautical tourism on the sustainability of marine environment in the case of the village ports of a small Island

The problem of underwater hull fouling has been mostly noticed by the pleasure boat owners when reducing the boat speed. In order to decrease the fouling of the underwater part of the hull, antifouling paints have been used. Some kinds of antifouling paints have become a serious environmental problem due to its very harmful effect on marine organisms and also, indirectly, on humans. Scientific research conducted in this domain has confirmed contamination by toxic compounds as a result of the usage of antifouling paints over long period of time. The paper is focused on underwater hull maintenance, especially when applying antifouling systems on pleasure crafts owned by tourists and local residents, in the example of the village ports of a small island. A survey was conducted among the residents who use ports to determine their knowledge regarding the harmful effects of biocidal coatings and the possible harmless maintenance of the underwater hull part. This paper aims to indicate the necessary equipment and procedures in the two small local ports in order to maintain pleasure boats in environmentally acceptable manner

16Cr3Al-Hf ODS steel: Surface effects of high laser intensity of 1015 W/cm2 in ambiences of air, helium and vacuum

Behavior of ODS steel under high energy fluxes is important as it is one of the most promising fusion reactor materials. The addition of hafnium provides improved microstructure and therefore better mechanical properties at high temperatures, and the goal here was to investigate the effects induced on Hf-containing ODS steel by the action of high-intensity ∼1015 W/cm2 radiation obtained by ultrashort pulsed laser. Morphological and chemical parametric study of the surface was conducted at different work ambiences. New data were obtained on damage parameters, threshold fluences and chemical changes. Measured damage depths were ∼7.5 μm (air), ∼14 μm (helium), ∼48 μm (vacuum), which is somewhat lower compared to ODS steel without the addition of hafnium