Baseline Distribution and Diversity of MIC-Relevant Microorganisms in Compacted Bentonites after Incubation for 1 Year
Bibliographic record
Abstract
Abstract The Materials Corrosion Test (MaCoTe) project at the Grimsel Test Site (Switzerland) is being used to provide experimental data for modeling the effect of the bentonite buffer on microbially-influenced corrosion (MIC) in deep geological repositories for spent nuclear fuel. Using culture-based and molecular culture-independent methods, we evaluated bacterial characteristics in bentonites compacted to bulk densities of 1.25 g/cm3 and 1.5 g/cm3 after one-year in-situ incubation in MaCoTe borehole modules. Abundance of aerobic and anaerobic microorganisms in the uncompacted MX-80 bentonite used in MaCoTe did not exceed 102 Colony-Forming Units per gram dry weight. Numbers of sulfide-producing microorganisms inside the highly-compacted bentonite (HCB) was <102 Most Probable Numbers per gram dry weight. Diversity was limited mostly to Gram-positive bacteria of the phyla Firmicutes and Actinobacteria that are able to survive the stresses found in carbon-scarce and arid clays. Aerobic spore-formers of the families Bacillaceae and Streptomycetaceae predominated in bacterial 16S rRNA gene sequences from friable MX-80, though Gram-negative Proteobacterial families, i.e. Xanthomonadaceae and Pseudomonadaceae, were also detected, indicating their ability to survive in the uncompacted clay. Compaction of clays to a density of 1.5 g/cm3 worsened conditions and almost completely-inhibited bacterial activity and spreading inside the HCB, consequently minimizing risks of biodeterioration and MIC inside HCB, even though environmental conditions outside of HCB were favorable for bacterial growth.
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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 | 0.000 |
| 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".