Laser absorption spectroscopy-based ultraportable analyzer for δ18O and δ2H in water.
Bibliographic record
Abstract
Stable isotope analysis of water 2H2O and H218O are powerful tracers to understand the different hydrological processes like ecohydrological processes, and hydroclimatic processes [1]. The measurement of δ2H and δ18O in water samples using laser-based absorption techniques is adopted increasingly in hydrologic and environmental studies. In contrast to the conventional Isotope ratio mass spectrometry (IRMS) technique, optical absorption spectroscopic techniques allow the realization of isotopologue-specific, non-destructive, and compact spectrometers with short analysis times with high-precision capabilities.ABB’s ultraportable water analyzers are compact, portable field-deployable laser spectrometers capable of making continuous, high-frequency measurements of δ18O and δ2H from multiple water sources. The instrument is based on Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) technique [2]. These analyzers are capable of measuring liquid water (GLA132-LWIA) or vapor (GLA132-WVIA). They are rugged and designed to handle both natural and isotopically enriched water samples. Users can leverage the precision and speed of the GLA132-LWIA by coupling it with a portable auto-injector to perform automated, unattended injection patterns on multiple samples.An important asset of this innovative approach based on OA-ICOS technology coupled with the portable auto-injector technology is its sample throughput, which allows one to measure approximately 90 samples a day corresponding to 720 injections each with a sample volume of 0.5 µL per injection per day. The precision (1σ) achieved corresponds to 0.6 ‰ for δ2H and 0.2 ‰ for δ18O. The analyzer’s ease of use, field portability, durability, and high throughput make it an excellent choice for reliable, high-performance measurement of freshly collected samples in the field, thereby opening a plethora of applications to understand the different processing governing the earth’s climate.[1] Tian, C.,et al., Sci Rep 8, 6712 (2018). https://doi.org/10.1038/s41598-018-25102-7[2] A. O’Keefe, et al., Chemical Physics Letters, vol. 307, no. 5, pp. 343–349, Jul. 1999, doi: 10.1016/S0009-2614(99)00547-3.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.016 | 0.006 |
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".