Induced Polarisation (IP) laboratory measurements on E. coli sand mixtures
Bibliographic record
Abstract
The aim of the MIRACHL project is the characterisation and monitoring of insituremediation of chlorinated hydrocarbon contamination using an interdisciplinary approach and geophysical methods, such as DCIP (direct current induced polarisation) to investigate the remediation process.To interpret these geophysical field IP data, lab investigations with different kinds of bacteria are necessary to assess the sensitivity of the methods for these specific applications. A first experiment was conducted with E. coli bacteria. Bacteria were grown together with a rich source of nutrients (Luria Bertanibroth LB) and mixed in different flasks with sterilised Ottawa sand. These bacteria-sand-mixtures were continuously shaken (30°C, 80 RPM) until defined endpoints (within 21 days) when the mixtures were harvested and packed in a4-point sample holder to measure SIP (spectral induced polarisation), TDIP (time-domain induced polarisation) and SP (self potential) under laboratory conditions. The same procedure was repeated with only the media-sandmixture to exclude any influences from just the nutrient and with water-sandmixtures.The results show a slightly increase in phase and a decrease in resistivity after several days with a decrease in phase that appears to coincide with dieoffof the bacteria. Resistivity in general was very low (between 310m) due to the highly conductive LB-media containing 5 g/L NaCl. As a result, the phase effects are very small too. The positive phase which could be observed for the E. coli measurements was surprising and is not yet understood. As expected, the water-sand mixtures showed almost no phase shift and slightly higherresistivity values. The influence of the nutrients is very small and results in a slightly lower resistivity than the E. coli-sand mixtures. The SP measurements show no clear tendency, but this is most likely due to limitations in the sample holder. The TDIP data needs to be further processed but the resistivity values are in accordance with the SIP results. Scanning electron microscope (SEM) images showed E. coli bacteria attached to the sand grains which could modify the grain surface (e.g. increasing the surface area and/or form a biofilm) and impact the IPmeasurements. In future, to support these observations with quantitative comparisons, the number of bacteria present in the sand will be determined using quantitative polymerase chain reaction (qPCR) to detect bacterial DNA (deoxyribonucleic acid).
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".