| 1. |
- Alves, Luis, et al.
(author)
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Revisiting the dissolution of cellulose in H3PO4(aq) through cryo-TEM, PTssNMR and DWS
- 2021
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 252
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Journal article (peer-reviewed)abstract
- Cellulose can be dissolved in concentrated acidic aqueous solvents forming extremely viscous solutions, and, in some cases, liquid crystalline phases. In this work, the concentrated phosphoric acid aqueous solvent is revisited implementing a set of advanced techniques, such as cryo-transmission electronic microscopy (cryo-TEM), polarization transfer solid-state nuclear magnetic resonance (PTssNMR), and diffusing wave spectroscopy (DWS). Cryo-TEM images confirm that this solvent system is capable to efficiently dissolve cellulose. No cellulose particles, fibrils, or aggregates are visible. Conversely, PTssNMR revealed a dominant CP signal at 25 °C, characteristic of C-H bond reorientation with correlation time longer than 100 ns and/or order parameter above 0.5, which was ascribed to a transient gel-like network or an anisotropic liquid crystalline phase. Increasing the temperature leads to a gradual transition from CP to INEPT-dominant signal and a loss of birefringence in optical microscopy, suggesting an anisotropic-to-isotropic phase transition. Finally, an excellent agreement between optical microrheology and conventional mechanical rheometry was also obtained.
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| 2. |
- Ginja, Catarina, et al.
(author)
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Iron age genomic data from Althiburos - Tunisia renew the debate on the origins of African taurine cattle
- 2023
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In: iScience. - : Cell Press. - 2589-0042. ; 26:7
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Journal article (peer-reviewed)abstract
- The Maghreb is a key region for understanding the dynamics of cattle dispersal and admixture with local aurochs following their earliest domestication in the Fertile Crescent more than 10,000 years ago. Here, we present data on autosomal genomes and mitogenomes obtained for four archaeological specimens of Iron Age (∼2,800 cal BP–2,000 cal BP) domestic cattle from the Eastern Maghreb, i.e. Althiburos (El Kef, Tunisia). D-loop sequences were obtained for an additional eight cattle specimens from this site. Maternal lineages were assigned to the elusive R and ubiquitous African-T1 haplogroups found in two and ten Althiburos specimens, respectively. Our results can be explained by post-domestication hybridization of Althiburos cattle with local aurochs. However, we cannot rule out an independent domestication in North Africa considering the shared ancestry of Althiburos cattle with the pre-domestic Moroccan aurochs and present-day African taurine cattle.
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