{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"3eab7815dd2b6672ce8b429b81b52be629994c40b034cf4b1e87641d3ebc0999","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["8c54e8380ad32cdaf0505efd8ae29121f5c10fb097b2e48a537f53c5556824fc","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"213e0482fc7ad87711b25dbc4cdbfd97f4ffcac85d90fa7449073cba21bcceb5","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"bio.lc-defects.twist-bend-mechanism","kind":"phenomenon","literature_status":"contested","n":"2","parents":[],"plain":"Bent-shaped molecules can form a nematic whose alignment spirals with a pitch of only about 100 Angstrom, the twist-bend nematic. Whether it forms because bending becomes energetically favourable or because of hidden polar order is disputed.","posed_since":"2013","precise":"The twist-bend nematic $N_{\\mathrm{TB}}$ (heliconical director, pitch about $8 \\times 10^{-7}\\ \\text{to}\\ 10^{-6}\\,\\mathrm{cm}$ in CB7CB) was predicted from a negative bend elastic constant $K_{33} < 0$ and alternatively explained through coupling to local polar order or flexoelectricity. Determine which mechanism stabilizes $N_{\\mathrm{TB}}$ and derive its coarse-grained elasticity (whether it behaves as a pseudo-layered smectic) from measured elastic constants and structure.","problem_ref":"8c54e8380ad32cdaf0505efd8ae29121f5c10fb097b2e48a537f53c5556824fc","references":"","settled_by":"Measurement of the elastic constants and polar order through the $N$ to $N_{\\mathrm{TB}}$ transition, compared with predictions of the competing theories.","status_note":"","title":"What stabilizes the twist-bend nematic phase?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"0cf65c4a8bd0370b972b8b5cff71abd3cfa9517e9f501183f1081f272ac9aacc","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"44f9d170bcd132140fdb86948db4355e8213a9f361d78feca1af760821cc654e","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"SnzVwoKbv85kDaPjGJdKU9T3q77__KEbrHx3So9COQshd_eN6V31zj9XjfexlTFKiSpImwO0IRWscYHVIWJoDg"},"schema":"pubphys.envelope/1"},"record_hash":"0cf65c4a8bd0370b972b8b5cff71abd3cfa9517e9f501183f1081f272ac9aacc","leaf_index":2594}