Clinopodium L. Taxa from the Balkans-Are There Unique Leaf Micromorphological and Phytochemical Patterns?

The concept of the genus Clinopodium L. has changed considerably since its first description. Most of the currently accepted species of the genus have traditionally been treated as separate genera in the group Satureja sensu lato: Clinopodium L., Calamintha sensu Miller or Moench, and Acinos sensu Miller or Moench. This study aimed to gain a better insight into the species diversity of Clinopodium L. from the Balkans by analyzing the taxa that have traditionally been placed in separate genera. The alkane profile and the micromorphological characteristics of the leaves are analyzed. The leaves are visualized using scanning electron microscopy, and alkanes are isolated using n-hexane as a solvent and analyzed using gas chromatography/mass spectrometry. The alkane profile showed the differentiation of the Acinos-group from the other taxa based on the dominant n-C31, while most of the other taxa contained n-C33 as the dominant alkane. The micromorphological features also showed clear differences between the previously recognized genera, especially in the capitate trichomes. The results showed that micromorphological patterns are highly variable in certain groups of the genus Clinopodium.

Phytochemistry and Micromorphology of Epicuticular Waxes in Four Juniper Species With Fragmented Distribution in the Balkans.

The cuticle is important in the interaction between the plant and its environment, especially in the dry areas. Four species of junipers from the section Sabina wild growing in the Balkans were selected to study leaf wax composition using GC/MS and GC-FID and its surface morphology under SEM to understand the correlation between the distribution and/or habitat of these species and their cuticles. SEM micrographs showed continuous, smooth epicuticular layers with crusts in all species but with a species-specific distribution of different 3D crystalloid types and different cuticle thickness. n-C33 alkane was the most abundant compound, followed by n-C29, n-C31, and n-C35, depending on the species and the site. The average chain length (N) was the lowest in J. phoenicea, but with the greatest dispersion around it. At the same time, the two most continental species (J. foetidissima and J. excelsa) show the N with the lowest dispersion around it. The statistical analyses confirmed the significance of climate on the evolution of the specific epicuticular wax composition in studied junipers.

Towards upscaling the valorization of wheat straw residues: alkaline pretreatment using sodium hydroxide, enzymatic hydrolysis and biogas production.

Lignocellulosic biomass is considered as a recalcitrant substrate for anaerobic digestion due to its complex nature that limits its biological degradation. Therefore, suitable preprocessing for the improvement of the performance of conventional anaerobic digestion remains a challenge in the development of anaerobic digestion technology. The physical and chemical characteristics of wheat straw (WS), as a representative lignocellulosic biomass, have a significant impact on the anaerobic digestion process in terms of quantity and quality of the produced biogas. This study aimed at investigating the enzymatic saccharification and detoxification of straw prior to anaerobic digestion with the final objective of enhancing the performance of conventional anaerobic systems of recalcitrant fractions of agricultural waste. The experimental activity was performed in lab and pilot scale treating WS. Alkaline delignification of straw using sodium hydroxide (NaOH) was studied prior to enzymatic hydrolysis for the production of easily biodegradable sugars. After defining the optimum conditions for the pretreatment scheme, the anaerobic digestability of the effluents produced was measured. Finally, the final liquid effluents were fed to a pilot scale anaerobic digester of 0.5 m3 volume, applying an increasing organic loading rate (OLR) regime (in terms of chemical oxygen demand (COD) from 0.2 to 15 kg COD/m3/day). The optimum conditions for the delignification and enzymatic hydrolysis of WS were defined as 0.5 M NaOH at 50 °C for 3-5 h and 15 µL Cellic CTec2/g pretreated straw at 50 °C. It was proven that the resulting liquid effluents could be fed to an anaerobic digester in the ratio that they are produced with satisfactory COD removal efficiencies (over 70%) for OLRs up to 10 kg COD/m3/day. This value is correspondent to a hydraulic retention time of around 7.5 days, much lower than the respective one for untreated straw (over 12 days).

Juniperus phoenicea var. turbinata (Guss.) Parl. Leaf Essential Oil Variability in the Balkans.

In the present work, the leaf essential oil from 97 individuals of Juniperus phoenicea var. turbinata (Guss.) Parl. from the Balkan Peninsula was analyzed. The essential oil was dominated by monoterpene hydrocarbons (45.5 - 71.8%), of which α-pinene was the most abundant in almost all of the samples (38.2 - 55.8%). Several other monoterpenes and sesquiterpenes were also present in relatively high abundances in samples such as myrcene, δ-3-carene, ß-phellandrene, α-terpinyl acetate, (E)-caryophyllene and germacrene D. Multivariate statistical analysis suggested the existence of three possible chemotypes based on the abundance of the four components. Even though the intrapopulation variability was high, discriminant analysis (DA) was able to separate populations. DA showed high separation between western and eastern populations but also grouped geographically closer populations along the west Balkan shoreline. The potential influence of the climate on the composition of the essential oil was also studied.

Essential Oil Composition of Centaurea atropurpurea and Centaurea orientalis Inflorescences from the Central Balkans - Ecological Significance and Taxonomic Implications.

The essential oil composition of Centaurea atropurpurea and Centaurea orientalis flowering heads (capitula) from Central Balkans have been determined by GC-FID and GC/MS analyses. In total, 121 compounds were identified, representing on average 97.7% of the oil composition. In all samples, sesquiterpenes were most abundant group, representing 53.9 - 74.0% of the total oil. Sesquiterpene hydrocarbons dominated in all studied populations of C. orientalis and C. atropurpurea, except C. atropurpurea f. flava in which essential oil was characterized with high level of oxygenated sesquiterpenes. The dominant components differed between species, and also between typical C. atropurpurea and C. atropurpurea f. flava. The most abundant compounds of essential oil of C. orientalis were germacrene D and α-cadinol. In C. atropuruprea, germacrene D and ß-caryophyllene were the most abundant, while caryophyllene oxide and ß-caryophyllene were dominant in C. atropurpurea f. flava oil. Taxonomical and ecological implications are further discussed.

Plasma reduction of bronze corrosion developed under long-term artificial ageing.

Reference Cu-based alloy with chemical composition and micro-chemical structure similar to that of ancient alloys has been used for carrying out the artificial long-term degradation test based on chloride enriched soil (chemical+soil) degradation. The results show that such degradation procedure produces natural like "patinas" as the ones grown on archaeological artefacts, from a chemical, structural and micro-morphological point of view. Glow discharge plasma technique has been employed for the treatment of the as-corroded bronze coupons. The gradual elimination of chloride-containing corrosion products in favour of the formation of more stable species and even the complete reduction back to copper has been observed. The chemical and metallurgical features have been determined by combined use of different analytical techniques such as scanning electron microscopy with energy dispersive X-ray micro-analysis (SEM-EDS), X-ray diffraction (XRD) and optical microscopy.