DISSOLUTION OF URANYL-OXIDE-HYDROXY-HYDRATE MINERALS. I. CURITE
Bibliographic record
Abstract
Dissolution experiments on synthetic crystals of curite, Pb<sup>2+</sup><sub>3</sub>(H<sub>2</sub>O)<sub>2</sub>[(UO<sub>2</sub>)<sub>4</sub>O<sub>4</sub>(OH)<sub>3</sub>]<sub>2</sub>, were done in HCl-H<sub>2</sub>O solutions of PH 2.1 and 3.5, in doubly distilled water, in Sr<sup>2+</sup>-HCl-H<sub>2</sub>O solutions of pH 2.7 and 5.5, and in Na<sub>2</sub>CO<sub>3</sub> solutions of pH 10.5 for 24 h at 60°C. Examination by atomic force microscopy and optical microscopy reveals the formation of etch pits under near-neutral to strongly acidic solutions, and the formation of hillocks under strongly basic solutions. A new approach to the morphology of uranyl-oxide minerals is used to calculate the stability of edges and the morphology of etch pits and hillocks formed on the basal surface of curite. These calculations predict that the probability of occurrence of edges decreases in the sequence: [001], [011], [0<em>kl</em>], <em>k</em> &lt; <em>l</em>, [0<em>kl</em>], <em>k</em> &gt; <em>l</em>, [010]. Edges along the basal surface and of all observed etch-pits and hillocks are [001], [110] and [0<em>kl</em>], <em>k</em> &lt; <em>l</em>, in agreement with the predictions. Etch pits formed at lower pH have lower relief and larger lateral extent than etch pits formed at higher pH, in accord with a decrease in stability of the edges with decreasing pH. Etch pits on the same basal surface have identical orientations, which violates the presence of a two-fold screw axis in the symmetry of the bulk structure. Cross sections of etch pits are characterized by steep edges and convex surfaces. A growth model of an etch pit formed in doubly distilled water explains this morphology by different rates of dissolution perpendicular to edges defined by right and left terminations of polyhedron chains. Differences in the symmetry of etch pits formed in Sr<sup>2+</sup>-bearing and non-Sr<sup>2+</sup>-bearing solutions are attributed to a nonstoichiometric detachment of polyhedra in the absence of Sr<sup>2+</sup> in the vicinity of the etch pits. The formation of hillocks under basic conditions and an increase in the density of etch pits with decreasing pH suggest that the formation of etch pits depends more on the degree of protonation of the basal face and its edges than on the degree of undersaturation of the solution with respect to curite.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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 teacher head, 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".