Decavanadates and polyanion-polycation interactions: from minerals to proteins
Bibliographic record
Abstract
The decavanadate polyanions [V 10 O 28 ] 6– , [H x V 10 O 28 ] (6–x)– and [(M 4+ x V 5+ 10–x )O 28 ] (6+x)– are constituents of the pascoite-family minerals. The interaction between the interstitial complex and the decavanadate structural unit may be analyzed using the principle of correspondence of Lewis acidity-basicity. The Lewis base strengths of the decavanadate polyanions vary from 0.054 to 0.135 vu and [V 10 O 28 ] structures can form from Cs + , Rb + , K + , Tl + and Na + ; simple cations with higher Lewis acidities are too acidic to form structures. Such cations bond to transformer (H 2 O) groups to form polyatomic cations that have lower Lewis acidities than the corresponding simple cations. In the pascoite-family minerals, the stereochemical details of the decavanadate ion are modified by (1) exploiting the two different patterns of bond-length arrangement in [6] V 5+ , (2) substituting tetravalent cations for V 5+ at one of the octahedra, and (3) protonating the decavanadate ion. These mechanisms change the individual Lewis basicities of the 26 external O 2– ions of the polyanion, allowing great versatility in the binding of decavanadate ions to constituent polycations of crystallizing structures. This suggests that the [V 10 O 28 ] polyanions may be used to induce co-crystallization of large aqueous polyatomic cations, facilitating their structural characterization. Decavanadate can also induce crystallization of proteins and is of major importance in protein crystallography because of this capability. Proteins and enzymes can bind to the decavanadate ion as very large polyatomic cations, modifying their function and showing potential for treating various forms of cancer, Alzheimer’s disease, AIDS, diabetes and COVID-19.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".