46 research outputs found
DdRAD sequencing and morphometric data analysis reveal a clear differentiation among the Tunisian populations of Onopordum nervosum ssp. platylepis Murb
No full textOnopordum nervosum ssp. platylepis Murb, an endemic plant in Tunisia, Algeria, and Libya, with spiny leaves and distinctive spiny-winged stems from the Asteraceae (Compositae) family, is used as a vegetable rennet in the production of traditional cheese. In Tunisia, the species is threatened and occurs in fragmented small populations isolated from each other. This study aims to evaluate the germplasm diversity of wild Onopordum platylepis to support future breeding efforts and aid in discriminating among populations with interesting phenotypic traits. Morphological characterization was conducted on five populations identified in the North (Tunis, Nabeul) and the center of Tunisia (Sousse, Kairouan, Monastir) to identify relationships among them. This involved adapting certain UPOV (International Union for the Protection of New Varieties of Plants) descriptors for Cynara cardunculus L. (cardoon) along with additional specific traits. Results revealed significant differences among the studied populations for the majority of traits with Kairouan (KN) population producing the greatest amount of biomass and flower heads. Additionally, a double-digest restriction-associated DNA sequencing study was conducted on O. platylepis individuals to confirm population differentiation. Results showed that Kairouan (KN) population provided the highest genetic diversity (pi = 1.5 x 10-3). Comparisons of pairwise Fst values between populations ranged from 0.1 to 0.13 and negative inbreeding coefficient (FIS) values were observed. According to our findings, the studied populations revealed important differentiation and maintained a moderate level of genetic diversity through frequent outcrossing or sequential gene flow. Both morphological and molecular analyses unveiled a distinct correlation between population structure and geographical distribution. Two distinct clusters were identified for the populations from the north and the center, suggesting that spatial segregation has resulted in lower genetic relatedness between these populations. In this context, it is important to monitor and reduce anthropogenic activity to protect genetic diversity, as well as ensuring the resilience of O. platylepis to environmental and climatic changes
Comparative study of the various methods of preparation of silicate solution and its effect on the geopolymerization reaction
No full textAbstractThis paper is based on the characterization of synthesized geopolymer binders based on either powder or solution silicate, and the amount of water contained in synthesized binders is determined to evaluate their possibility to coat a brick. The structural evolution of the formed geopolymers was investigated using FTIR spectroscopy. The mechanical properties were evaluated using compression tests. The structural evolution ensured that the solutions prepared from silicate powder or liquid had different degrees of polymerization, which modified the polycondensation reaction of the mixture. Nevertheless, the use of aluminosilicate solutions based on powder or liquid display similar behavior in a polycondensation reaction. The obtained materials show good mechanical properties, and it is possible to deposit this binder on the brick depending on the water content
Magnetization Reversal in (CoNi/Pt)N Dots Connected to a Large Area through Submicron Wide Channels
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Scanning near-field observation of magnetic domains in Pt/Co thin films and their development as a function of applied field
No full textGeopolymer binder based on powder or liquid alkali solutions precursors for bricks deposit sludge
No full textInternational audienc
Effect of calcination temperature of tunisian clays on the properties of geopolymers
No full textInternational audienceGeopolymers are amorphous three dimensional aluminosilicate materials that may be synthesized at room or slightly higher temperature by alkaline activation of aluminosilicates obtained from industrial wastes, calcined clays and natural minerals. Among the different family of geopolymers, two Tunisian clays (a kaolinite clay from Tabarka and illito/kaolinitic clay from Medenine) are tested for their feasibility of geopolymers at low temperature. The unfired and calcined clays were dissolved in strongly alkaline solution in order to produce consolidated materials whose pastes were characterized by their compressive strength. Hardened geopolymer samples were also submitted to X-Ray diffraction, FTIR spectroscopy and scanning electron microscopy analyses. The geopolymer strength is related to the structure and reactivity of the clay generated by thermal treatment and to the role of associated minerals in clays. The amorphous character of obtained geopolymers and the displacement of the IR wavenumber are signature of geopolymerisation reaction
The role of hematite in aluminosilicate gels based on metakaolin
No full textInternational audienceThis paper investigates the role of iron oxide in natural clay and its contribution to polycondensation reactions. Iron oxide was added to pure kaolin in the same proportion as Medenine clay with different amounts of potassium hydroxide. The physicochemical and structural properties of these materials were determined by infrared spectroscopy, scanning electron microscopy, thermal analyses (DTA-TG) and X-ray diffraction. The amorphous character seen in the diffractograms obtained from the materials and the displacement of the IR wavenumber are indicative of a polycondensation reaction. The representative characterization of the microstructure of different samples using electron microscopy highlights the nonreactivity of iron exhibited during consolidation. In general, the contribution of iron oxide seems to be small under the conditions described here
