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Povzetek: The study deals with the characterisation of paint layers from the wall paintings that decorated two excavated Roman villae rusticae in Slovenia. The villa in Mošnje, located in the NW of Slovenia, was built in the 1st half of the 1st century AD and was in use until the end of the 2nd century AD, while the coastal villa in Školarice, built in the second quarter of the 1st century AD, remained in use until the mid-5th century. Stratigraphy and painting techniques were studied using optical microscopy, with pigments identified via Raman microspectroscopy supported by FTIR microspectroscopy and SEM/EDS. The results of this analysis revealed that whereas the Školarice wall paintings were mainly executed using the fresco technique and some areas with the secco technique, both techniques were identified equally in the Mošnje paintings. Red ochre, lime white and carbon black pigments were identified in both the Mošnje and Školarice paintings, although the latter were also characterised by the use of yellow ochre and green earth.
Ključne besede: Roman villas, mural painting, pigments, Raman microspectroscopy
Objavljeno v DiRROS: 16.09.2024; Ogledov: 398; Prenosov: 150
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Povzetek: Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.
Ključne besede: biological pigments, cyanotoxins, ecology, hydrobiology, data, datasets
Objavljeno v DiRROS: 24.07.2024; Ogledov: 567; Prenosov: 429
Celotno besedilo (1,32 MB)
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Povzetek: In coastal seas, a variety of environmental variables characterise the average annual pattern of the physico-chemical environment and influence the temporal and spatial variations of phytoplankton communities. The aim of this study was to track the annual and interannual variability of phytoplankton biomass in different size classes in the Gulf of Trieste (Adriatic Sea) using phytoplankton pigments. The seasonal pattern of phytoplankton size classes showed a co-dominance of the nano and micro fractions during the spring peak and a predominance of the latter during the autumn peak. The highest picoplankton values occurred during the periods with the lowest total phytoplankton biomass, with chlorophytes dominating during the colder months and cyanobacteria during the summer. The highest number of significant correlations was found between phytoplankton taxa and size classes and temperature, nitrate and nitrite. The most obvious trend observed over the time series was an increase in picoplankton in all water layers, with the most significant trend in the bottom layer. Nano- and microplankton showed greater variation in biomass, with a decrease in nanoplankton biomass in 2011 and 2012 and negative trend in microplankton biomass in the bottom layer. These results suggest that changes in trophic relationships in the pelagic food web may also have implications for biogeochemical processes in the coastal sea.
Ključne besede: phytoplankton, biomass, phytoplankton size classes, phytoplankton pigments, HPLC, interannual variability, trends, Adriatic Sea
Objavljeno v DiRROS: 16.07.2024; Ogledov: 561; Prenosov: 364
Celotno besedilo (2,43 MB)
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Povzetek: A model organic pigment (diketopyrrolopyrrole) is encapsulated by a silica coating in order to improve its photochemical stability. Unlike in previous works where single-layer silica coatings were used for similar purposes, we here propose creation of a multi-layer silica shell synthesized via in-situ sol-gel method, which should significantly improve the homogeneity and thus the protection ability of the coating. This is done by repeating the basic two-step process (pigment surface modification and silica encapsulation) several times, creating the final protective shell in a layer-by-layer fashion. The compositional and structural properties of the prepared coatings is studied using Fourier-transform infrared spectroscopy, differential thermal and thermogravimetric analysis, nitrogen adsorption measurements and transmission electron microscopy. Photochemical stability of non-encapsulated and encapsulated pigment particles is evaluated via the so-called fast-irradiation method. Various correlations between the essential coating properties, such as thickness, porosity, SiO2 content, and the corresponding photochemical stability of the samples are established and discussed in detail. As a whole, our results confirm the basic hypothesis, that multiple-layered silica shells show improved pigment protection ability in comparison to the single-layer coatings.
Ključne besede: organic pigments, silica coating, encapsulation, morphology, photocemical stability
Objavljeno v DiRROS: 27.03.2024; Ogledov: 1067; Prenosov: 423
Celotno besedilo (1,78 MB)
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