In Situ X-ray Absorption Spectroscopic Study of the Adsorption of Ni<sup>2+</sup>on Fe<sub>3</sub>O<sub>4</sub>Nanoparticles in Supercritical Aqueous Fluids
Bibliographic record
Abstract
In situ X-ray absorption spectroscopy (XAS) measurements were made on Fe 3 O 4 nanoparticles in supercritical aqueous fluids to study their reactivity with Ni 2+ ions and to investigate the structural properties of the reacted nanoparticles. XAS spectra were measured from Ni 2+ added to an aqueous solution containing Fe 3 O 4 nanoparticles at temperatures up to 500 °C. The XANES and the EXAFS data indicate that reactivity of Fe 3 O 4 nanoparticles with Ni 2+ ions is negligible to 300 °C but becomes significant in the 400–500 °C temperature range. Analysis of Ni K -edge extended X-ray absorption fine structure (EXAFS) using an atomic cluster model based on the spinel structure shows that Ni 2+ adsorbs predominantly on octahedral sites of the surface of nanoparticles in aqueous fluids at 400–500 °C. The EXAFS structural results are consistent with diffusion of Ni into the near-surface region of the Fe 3 O 4 nanoparticles in the aqueous fluid at 400 and 500 °C.
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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 | 0.000 | 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 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".