The UBC ATMOX chamber: An 8 m <sup>3</sup> LED-powered modular environmental chamber for indoor and outdoor atmospheric chemistry
Bibliographic record
Abstract
Abstract. Environmental chambers are controlled reaction vessels used to investigate atmospheric processes such as photochemical smog, atmospheric fate of molecules and secondary organic aerosol formation. Environmental chambers are typically equipped with UV-A fluorescent lights with wavelengths between 350 and 410 nm or xenon lamps with wavelengths between 300 and 800 nm. However, these types of lights increase the temperature of the chamber, are energy intensive and are not tunable to specific wavelengths. Fluorescent lights are also becoming redundant in the light industry. To address these issues, we prototyped the use of light-emitting diode (LED) lights from Violumas on our 8 m3 environmental chamber for photochemical experiments to enable stratospheric, tropospheric and indoor light conditions. The University of British Columbia (UBC)'s Advanced Techniques for Mechanisms of OXidation (ATMOX) chamber was assembled with custom-made wide-angle LEDs of six different wavelengths from Violumas: 275, 310, 325, 340, 365, 385 nm. We also added LED grow plant lights (Feit Electric) for irradiance between 450 and 630 nm. The LEDs were wired to a potentiometer control panel to modulate their output on a per wavelength basis. We used a total of 1440 custom LEDs and 1320 commercial grow plant LEDs, costing USD$ 44,951 and USD$ 1,300, respectively. We demonstrate their energy efficiency, their ability to generate less heat, and their ability to generate wavelength-specific photochemical processes. Furthermore, chemical actinometry using NO2 enabled us to calculate a photolysis rate constant (JNOx) ranging from 2.28 × 10-4 to 4.93 × 10-3 s-1, which is nicely comparable to 4.50 × 10-3 s-1 in Vancouver, Canada during the summer solstice. In addition to the lights, the UBC ATMOX chamber was designed to be particularly modular. The chamber frame has 12 aluminum T-slot rails (2.66 × 2.66 × 3 m, 80/20 Rocky Mountain Motion Control), and a pulley system to enable the 8 m3 bag to collapse and inflate, to perform batch or continuous mode experiments. The Teflon chamber bag has sealable openings at each corner to allow access to the interior of the bad for regular thorough cleaning. Overall, our chamber is allowing us to study topics of current interest in atmospheric chemistry: from the fate of indoor air fragrances to cannabis emissions and from wildfire aerosol photochemical changes to the biogeochemical cycling of selenium.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.013 | 0.002 |
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".