Crystal structure and NMR of an α,δ-peptide foldamer helix shows side-chains are well placed for bifunctional catalysis: application as a minimalist aldolase mimic**

We report the first NMR and X-ray diffraction (XRD) structures of an unusual 13/11-helix (alternating i, i+1 {NH−O=C} and i, i+3 {C=O−H−N} H-bonds) formed by a heteromeric 1 : 1 sequence of α- and δ-amino acids, and demonstrate the application of this framework towards catalysis. Whilst intramolecular hydrogen bonds (IMHBs) are the clear driver of helix formation in this system, we also observe an apolar interaction between the ethyl residue of one δ-amino acid and the cyclohexyl group of the next δ-residue in the sequence that seems to stabilize one type of helix over another. To the best of our knowledge this type of additional stabilization leading to a specific helical preference has not been observed before. Critically, the helix type realized places the α-residue functionalities in positions proximal enough to engage in bifunctional catalysis as demonstrated in the application of our system as a minimalist aldolase mimic.</p

Linguistic Situation in Twenty sub-Saharan African Countries: A Survey-based Approach

Data on second languages in sub-Saharan Africa are hard to come by. Consequently, any source that contributes to our knowledge beyond the level of primary languages should be appreciated and exploited. This article utilises Round 4 of the Afrobarometer Survey that collects information on ethnicity, home, and additional languages in 20 sub-Saharan African countries. The study has three main contributions. First, it overviews and compares some widely used sources that contain linguistic data and investigates why they show such a diverse picture on language use patterns. Second, it applies the ICP which, according to the author’s knowledge, is the first linguistic measure that takes multilingualism into account. Third, it shows how a simple graphic representation of the ICP can be used to visualise the most important dimensions of a country’s linguistic situation including the order of languages according to their size, the presence of monolingual speakers, and the relation between vernaculars and the former colonisers’ languages. The study findings are expected to be of interest to scholars engaged in language policy and planning and language-related development issues