A friend of mine and I have been talking about orchids lately. The dendrobium papilo comes from a relatively cool growing area in the Phillipines. What that means is it probably is happy at typical household temperatures during Canadian winters, slightly warmer during the day, and a cool drop at night. What it is not so happy about is the humidity. Some quick googling suggests that 70-80% RH would be appropriate for this plant in its natural habitat. Naturally, this is impractical to maintain in a home and good practice would be to support the plants needs by keeping it regularly watered and preventing the growing media from growing out. But what if we could bump up the humidity even a little bit? Surely 50% RH is better than 30%? My friend wondered if putting a pebble tray beneath the plant might do any good.
Here’s where the sketchy science comes in. At 21C, 30% RH gives us an absolute humidity of 5.5 g/m3 (https://www.ready.noaa.gov/READYmoistcal.php). To get it up to 50% RH, we would need 9.1 g/m3, with the inrease required being 3.6 g/m3, that doesn’t seem too much. Let’s pretend we’re in the bathroom in the average US home of 40 square feet, with a height of 10 ft. That gives us 11.3 m3 and would require about 40.7 g of water added into the air. This is readily done by taking a shower. However, hopefully shower users have noticed their bathrooms drying out over time. The turnover rate of air in a house starts around once every 3 hours. For convenience, let’s consider that 1/3 of the air is replaced every hour. At the start of the hour, we’ve added the 40.7 g. We lose a third of this if the air (TWC: 102.8 g) is well-mixed (-34.3 g) and it is replaced with the 30% RH air (+20.7). To maintain the 50% RH, we need to make up for the difference and add 13.6 g. Since we’re no longer runing the shower, how long does it take to add 13.6 g into the air passively via evaporation?
Let’s use an airflow rate of 20 m/s (72 km/h) if the pebble tray is sitting right in front of the vent. For a 3 inch saucer, that’s about182 cm2 of surface area. Let’s say 300 cm2 (0.03 m2) if you add lots of porous pebbles. Under the most efficient evaporation rate (when the RH is 30%), the evaporation rate is 131.7 g/hour, or 131.7 mL/hour. That’s pretty darned good! All you need to do now is add 3 kg of water a day. The tray is probably at most 3 cm deep by the way, so it can hold just under 550 cm3 of water, or 550 mL. So you only need to top off every 3-4 hours really.
The problem is, none of what I’ve posed above is realistic. First, the air being exchanged in is probably close to 0. Currently where I am, it’s 80% RH outside. From -10 C outside to 21 C indoors, we would have just under 10% RH air coming in. So instead of adding 20.7 g, into the air with the exchange, we’re adding about 6.4 g of water. Which means we need to make up for an additional 14.3 g, double what we had earlier for a total of 27.9g. Our plants usually don’t sit right by the vent, and I had used the *main* duct velocity. According to this reddit post (https://www.reddit.com/r/AskEngineers/comments/t5yfj0/how_to_calculate_air_velocity_after_it_exits/), the plants need at least 0.5 m/s for good airflow (which I pointed out might be a concern with resting your plant right on top of a tray if it covers up the entire surface). Let’s say the airflow is 5 m/s right out of the vent, which is about the upper realistic value for a low pressure duct. It is likely much lower elsewhere, but let’s call it 5 m/s anyhow. Now we’re at an evaporation rate of 390.0 g/hour (https://www.omnicalculator.com/physics/evaporation-rate#google_vignette). At 0.5 m/s, this is reduced to 112.1 g/hour. Still, about 3 times the replacement rate that we needed. Right now we’re assuming that the cooler, higher humidity air from above the tray is mixing into the overall bathroom and the airflow is directly passing over the surface.
At this point, the bathroom is looking like a pretty good spot. There are some unrealistic assumptions I’ve made, like the hourly time step, but overall it might be possible to maintain 50% RH in the bathroom!
Now let’s think about the living space. Let us increase the size of the space and call it 50 m3. The water content at 50%RH in this room is 455 g, and the water loss from the 3x turn over is -151.7 g + 29.3 g = 122.4 g. The same saucer is placed somewhere with good airflow, and evaporates at 112.1 g/hour. This is now less than our target 50%RH. If you run this forward by 24 hours with continual water top-ups, you end up with 455 g – (122.4 g – 112.1 g) x24 = 455 g – 247.2 g = 207.8 g of water. That’s 4.15 g/m3 and about 23%RH (note that evaporation will of course increase once you hit below by previous threshold of 30% RH).
Here’s the real practical test. Spill about 100 g of water in a relatively small room that still has airflow. Measures the relative humidity every few minutes in the room. How long does it actually take to evaporate? If you start at 30% RH, what do you end up with after a few minutes? (For reference, I add about 1.5 kg of water into my ~ 20-30 m3 room each day just topping up plants and fish tanks, my room sits between 45 – 50%RH. The water loss is mostly via transpiration through plants, and dehydration of the extremely high surface area of spaghnum moss topping most my plants, not the fish tank! The surface area of the tank is a bit under a square meter, but it’s a shallow tank where the humidity is partially trapped by a plexiglass pane so it does not mix readily into the rest of the room.)
Sometimes life is stranger than fiction. Here I am, waiting on a phone call from IT after I found out that my access token has never been granted (despite using it for 3 years or so) and my account doesn’t have VPN access and never has. I wonder. Chances are I just punched in my new PIN wrong so many times that I got turfed out of the system and accidentally overwrote a few things. The extra fun part is when my password shows up as my username during the restoration process.
This week we were asked to reflect on the science portrayed in one of our favourite shows. Admittedly, I am not a huge consumer of classical media and often can’t remember the details (The Expanse is a great book, but I didn’t finish the show, and I didn’t enjoy The Martian enough to critique it). I thought I’d share about one of my favourite animes instead, an absolute classic of a time travel show: Steins;Gate (Fig. 1).
Figure 1. Steins;Gate game art. This was released as a visual novel at first before the anime adaptation. The main protagonists are shown on the cover with a falling phone and time travel evice.
Steins;Gate appears to be a comedy/slice-of-life anime that starts off with our male protagonist Hououin Kyouma/Rintaro Okabe who suffers from delusions of grandeur and believes himself to be a mad scientist. He is a high-school student attending a university during the summer. His close friends include Daru (a stereotypical, overweight, pervy nerd who salivates over a picture of the Large Hadron Collider from SERN on his laptop background) and Mayuri (a slightly younger female cosplay designer that is portrayed as airheaded). The anime takes place in Akihabara, a well known “techy pieces and odds and ends” sort of place in Tokyo that is very real (the equivalent of this in Osaka is Den-Den Town!) where they build weird gadgets and eventually…make a gellifying microwave that leads to time travel by the means of text. Oh, and in the meantime, Kyouma encounters Makise Kurisu outside of a summer lecture series by a famous scientist after he interrupts the theories on time travel.
Here’s where the real-life and science really begin to blur. Kurisu is a prodigy in neuroscience research and has published in “Sciency” (Fig. 2). She gets roped into the antics of the other high-schoolers as they try to decipher the gel-formation and the mini-blackhole that is somehow forming within the microwave. Say what.
Figure 2. A screenshot from the translated game. Makise Kurisu on the front cover of the print magazine Sciency.
The show rapidly shifts towards existential crisis mode as the text-activated microwave sends texts into the past, resulting in subtle changes in the timeline and the group being hunted down by evil time travel aware people. Kurisu builds a device to send back memories into the past so Kyouma can download his thoughts each time from his phone while they try to restore the mistakes they’ve made and aim for a happier timeline. At some point they also need an ancient IBN (IBM) machine to hack into SERN to erase any data they had on the lab.
I really love this particular anime. It’s an incredible snapshot of the times and is littered with very specific jokes (many of which might cause pause today) and reminds me of my own high school experience in many ways. It convinced me to try Dr. Pepper (Fig. 3). Also quick shoutout to the translation team that actually broke down every single joke in the visual novel version! It’s still on my todo list to clock in the 80 or so hours to play through the entire game…
Figure 3. Dr. Pepper. Me despising Dr. Pepper is probably one of my biggest “failings” as an otaku in my school days.
Here are some fun tidbits that might be worth exploring!
Black Hole Theory – the crossing of event horizons results in time travel
Light Speed Theory – presumably moving faster than the speed of light leads to some sort of future travel. It is unclear what this actually means in the show
Tachyon Theory – particles that move faster than the speed of light and could be used to send messages by bouncing off a mirror and returning before it left
Wormhole Theory – this one is explained slightly more in-depth during a lecture. The show explains this as a hole where the time between the entry/exit is zero. If a wormhole is sufficiently long, then the arrival time is in the past. Returning to the entry, time travel occurs at the same location. One of the points made here is that exotic matter is required to stabilize the worm hole
Exotic Matter Theory – material with abnormal properties that behave the opposite to F = ma, now confirmed to exist! This would allow for physical movement of objects into the past
and so on and so forth
Without the requisite physics background, I can’t comment how accurate some of these descriptions were. The show uses what appears to be the tachyonic antitelephone where if a signal were sent sufficiently fast enough (greater than the speed of light), then the signal causes an effect before the signal is even sent. To send things faster than the speed of light, a mini Kerr-black hole is created in the microwave. This Kerr black hole is stable only during very specific hours of the day, someone directly by the activity of CRTs on the ground floor from the group’s landlord (Fig. 4). The particular frequencies of the components in perfect resonance are handwaved, and even the group is baffled. But repeated use and testing shows that this indeed is the situation. Science!
Figure 4. Mr. Braun with his I ❤ CRT apron. This is the video game art.
This is fine and dandy when the data limit is 36 bytes (this is shown by the cropping of text messages when long messages are sent), but really falls apart when they start sending entire human memories through the black hole through physical compression of the data (Fig. 5). In the show, the urgency is off the charts so no one stops to think whether or not this really works. We also see that the memory downloading when Okabe picks up the phone causes an immense amount of strain but is near instantaneous, uncompressing in his brain. I suppose this could happen if the compression was only during the blackhole time travel transfer moment, and it immediately pops up as is.
Figure 5. Ah yes. Let’s put on this cute little headset and pull out all of your memories while simultaneously beeping them through the microwave phone. Ding! Also check out that IBM keyboard!
We also see the arrival of a PHYSICAL craft towards the latter half of the show, when Daru’s daughter from the future resistance arrives, crash landing on a building that is shown both damaged, and undamaged in the very beginning of the show. This device somehow contains enough energy to simply jump in time, twice! The device was developed to prevent SERN (now clearly an evil research group vying for world domination) from discovering time travel at all by stealing the group’s research. We have still yet to see if this is at all possible, since the travel occurs in 2036. Unlike exotic matter, I’m not sure if we’ll suddenly see a satellite-like craft crashing into a high-rise building in 2010 retroactively.
Some other fun quirks in the show include:
the presence of maid cafes (very real)
@channel (a 2chan reference perhaps)
Rai-net tournaments (a play on the many card game tournaments in Japan, it reminds me of Digimon somewhat)
Akihabara as a whole (the show uses real locations and buildings)
and flip phones! What a time. The show does an excellent job showing everyone’s individual phones and phone charms. In the visual novel (the show is based off of a game), the choices are made all through text message! You can also choose to pick up or ignore phone calls! Its a throwback to see everyone in the show “text” to email addresses, which remains a baffling situation to me
Back in the days when it was socially acceptable to admit to owning a Nintendo Wii (no U to be seen back then), I was a huge fan of playing Super Paper Mario when I could borrow it from a friend (Fig. 1). The storyline was typical, Mario and friends travel through a number of dangerous worlds, defeating baddies, collecting goodies, and facing off the final boss at the end. I confess I never defeated the game (but no spoilers here!), as the save system was in such a way that I would persistently load into the final play-through with minimal health and entirely forget the controls each time I tried. Perhaps the smart thing would have been to restart all over again. But this is not important.
Figure 1. Super Paper Mario game cover. Anyone else remember this game?
Super Paper Mario was a game that let you flip between 2D and 3D. This flipping ability let’s the player access an additional layer of the world that previously was hidden. You could make changes in the 3D world that affected the way the 2D world worked, by moving things in and out of the plane, and sometimes seeing passages that prevently didn’t exist. The 2D and 3D worlds were intimately related. This is my convoluted and off the cuff explanation for Fourier transforms (I’ll find out after this once I reread the Wikipedia entry for the umpteenth time).
Figure 2. Completely unrelated to this post, but I once made some fanart of this scene in highschool for an art project. I found the art style to be very charming. I want to say it was for an illustration class, but had I done it again, I think I would have done a 3D installation for this recreation.
Imagine you’re dealing with this convoluted passage way, trying to navigate your way to a Pure Heart. You flip into the 3D space and you see that there is a frequency, a regularity, or perhaps everything is just a little lower than you’d like. You bonk some blocks with your head, dodge some goombas, and flip back into 2D. There it is! A straight path to the exit. It was there all along, but you had to move things in the 3D world to access it.
In my world, this is exactly what Fourier transforms are for. You take a signal that seems rather confusing, and want to see some of it’s characteristics in the frequency domain. Once you’ve flipped into frequency space, you can see all the details that make up your time signal. This might give you some clues to your final destination. But you also might need to tweak a few things to clean up the interpretation. By applying a function that can only be done in the frequency space, you have affected your time domain as well. You can see the results of your work by flipping back into the time domain.
Fourier transforms can be applied to more than time signals, and work for any sort of complicated situation you have. Say you want to recreate a complex squiggle in 2D, but want to make it exclusively out of single curves in 3D, you can do that. There’s more to it, but let’s say I have a strong itch to find a second-hand Wii and give Super Paper Mario another shot. Bleck!
This was a late night (4 am) writing exercise inspired by some online discussion I had been privy to. All mistakes are my own. Math is likely incorrect. There are MANY ways in which to improve upon this work, only some of which are addressed below. Please excuse the lack of equation formatting, turns out LaTeX plug-ins require upgrades! Minor edits may be ongoing!
Abstract
I investigate the effects of shockwaves and in light of aquarium hobbyists concerns regarding impulses potentially damaging glass tank walls. I compare the potential peak pressure experienced by the aquarium walls in the case of a manmade object travelling at 3 km/s at 0.1 km altitude to the theoretical strength of the glass walls and find that failure is unlikely to occur if the glass ratings are reliable. However, the silicone seams may be a point of weakness. Additionally, I did not evaluate the compound effects on glass strength from other damaging sources such as scratches, casual impacts, and long-term use. Suggestions to minimize the impact include the use of diffusion (reflecting barriers) and absorption (highly porous material converting kinetic energy to heat), though their efficiency is not evaluated. Lastly, I note some of the short-comings of this work.
Introduction
Impulsive events occur on a daily basis, of which the common aquarium is hopefully designed to withstand these bumps and knocks. For larger events such as meteor impacts and the passing of fighter jets, it is difficult to believe that the various aquarium manufacturers take these factors into account when setting out safety standards and designing their warranties. Recently, an innocent question was asked online, “How to protect my aquarium from shock waves caused by sonic booms?” (u/WassufWonka, 2024). This sparked a brief discussion that was rapidly quelled, though subsequent posts were made (u/memerobbin, 2024; u/laced1, 2024) and others discussing moderation. Before it concluded, some points were brought up, including the relative pressure caused by shockwaves from passing fighter jets, equilibrium pressure inside and outside of the aquarium, and whether aquarium glass was sufficiently strong enough against said pressures. Suggestions for limiting the impact including foam mats as padding, tape in cross designs, and transferring fish to buckets for the time being. A brief reassuring post from u/sldomingo (2024) appeared explaining how the shockwaves would be absorbed by water and not to worry before promptly being removed.
In this article, I briefly investigate the potential source of impulse, describe the range of pressures from the shockwave as it encounters the aquarium glass, and consider whether standard aquarium glass is sufficient to withstand these impulsive events. I also discuss the various ways in which an aquarium can fail from other events, and how one can mitigate the effect of shockwaves on glass with a brief note on the strength of silicone seals.
Methods
Source Impulsive sources impacting aquariums can vary, including repeated finger tapping on the glass, a young toddler wrecklessly scratching glass with a set of keys while an absent-minded parent looks on, to the sonic booms from fighter jets overhead. Sonic booms are generated when an object moves faster than the speed of sound, causing a stacking of pressure waves “breaking the sound barrier”, a shockwave. This shockwave and can come from natural sources, such as incoming meteors, and manmade sources, such as space shuttle return or fighter jets.
The shockwave that is released travels at speeds higher than the speed of sound for several wavelengths, before relaxing and continuing to travel at the local speed of sound (ReVelle et al, 1976). The shockwave can be approximated as a cylindrical source. At sufficiently far distances, it can be approximated as a line source with one main overpressure event. We can estimate the range of overpressures from the shockwave using the generalized steps:
Estimate the source energy available for sonic boom
Convert source energy to overpressure at the surface
For expediency, I will use existing data on manmade hypervelocity objects. The return of Stardust suggests maximum overpressures of 1.153 +/- 0.096 Pa including several delayed infrasonic arrivals with equipment sampling frequency of 100 Hz (ReVelle and Edwards, 2007). Estimates of source energy range from 1.557E-6 to 2.437E-5 ktTNT (1 ktTNT = 4.185E12 J) for the first instance of infrasound arrivals with a distance of 32.6 km and height of 42.7 km. Secondary arrivals have a maximum overpressure of 0.207 Pa with around a 10 s delay, and estimated energies of 6.275E-7 to 1.206E-5 ktTNT when Stardust was at a distance of 26.1 km and a height of 32.07 km. Stardust had an initial return velocity of 12.9 km/s with simulations estimating a mean velocity of 3.0 km/s (ReVelle and Edwards, 2007).
Siber et al. (2024) also provided data on the OSIRIS-REx capsule return. For a point of reference, station A05 from the Gems station was located closest (~13 km away, height unknown), with a maximum amplitude recorded at around 1.5 Pa (Fig. 7). They found that the shuttle was travelling at approximately 2.9 km/s based on the seismic data. Notably, the shuttle achieved a theoretical maximum of Mach 45.6 at 95 km altitude, and the shockwave was estimated to be produced at 80 km altitude.
Theoretical Fighter Jet Let us consider a theoretical fighter jet, capped at Mach 9.6 (3.3 km/s) per a google investigation. This is sufficiently close to the case of the estimated Stardust return. We now estimate the potential distance of a fighter jet passing by over a home in Beirut, Lebanon, let’s say 0.1 km (or 100 m). Considering the mountainous environment, lower flying does not seem particularly sensible, though certainly feasible. Let us also consider this the slant distance, as it is possible a plane would be flying directly overhead.
Scaling Laws We can now use some of the existing scaling laws to estimate the total overpressure that may be experienced 0.1 km below a passing jet if we can assume scaling laws apply (I should probably find references for this, but I’ve been reasonably assured below 100 km this is not too silly to do), then del(p_1)/d_1=del(p_2)/d_2, which can be rewritten as del(p_2) = del(p_1)*(d_1/d_2)
For the first arrival, I found an overpressure of 619.2 Pa, and for the secondary arrivals, 85.6 Pa. For a point of reference, atmospheric pressure is 101325 Pa. The pressure exerted by water in a full tank can be estimated using an example of a 33 gal standard aquarium with dimensions of 48’’ x 13’’ x 12’’. Assuming the 12’’ dimension is the base, the area of the outwards facing walls are approximately 0.4 m2 and 0.1 m2 respectively. The pressure in the tank can be calculated using force, F=rho*g, with rho=1000 kg/m3 as the density of water, and g=9.8 m/s2, gravitational acceleration on Earth. For the respective faces, the pressure exerted by the water in the tank is 24500 Pa (24.5 kPa) and 98000 Pa (98.0 kPa, or 0.098 MPa) respectively. Thus, the arguments that the pressure within the tank are greater than the impulsive events appears to hold.
Note that the pressure from the sonic boom in this case is within the blast radius, before viscous relaxation. The blast radius is ~3.0*R_0 (Ceplecha et al., 1998), where the characteristic blast radius R_0=1.05*M*d_m where M is the Mach number, and d_m is the diameter (ReVelle, 1976). Let’s say the blast radius is then 3*1.05*9.6*13.7 m = 414.3 m, greater than our hypothetical case of 100 m altitude. At a more realistic Mach number 3, the blast radius is 129.5 m. This suggests that our pressure estimations may be underestimations for this particular case.
Let us assume that the source of the shockwave from the OSIRIS-REx return was at a distance of ~81 km (assuming 80 km altitude), this corresponds with 1215 Pa at a distance of 0.1 km. Thus, we have a general range of overpressures, between 85.6 Pa and 1215 Pa from a shockwave. On the higher end of the estimated overpressures, this is about 8% of the pressure of water exerted on the long face of the tank.
For a 5 mm thick tempered glass pane, I found an average of 19800 psi compressive strength (I have misplaced this reference, Wikipedia suggests 10000 psi for a 6 mm pane), with Wikipedia giving glass a tensile strength of 1000 psi (Tempered Glass, n.d.; Strength of Glass, n.d.). Say the average tempered glass is 4x stronger than regular glass, this gives us a tensile strength of 1000 psi (6.8 MPa), several times stronger than the overpressure effect from a sonic boom (though later Wikipediaing suggests tempered gl. This suggests that there is no immediate concern that a single sonic boom from a nearby fighter jet travelling at Mach 3 will be of immediate concern.
Discussion
Contradictions This is odd, many horror stories abound about surprise aquarium blowouts, or an accidental hit from a bb gun might be up to 0.5 kg of force over a 4 mm diameter pellet at 20 ft is actually around 3 MPa, half the compressive force glass can withstand. It’s not like we’re tearing around our aquariums either so tensile force doesn’t necessarily come into play. One consideration might be the strength of the silicone seals. Tensile strength of silicone sealant is around 0.5 MPa. Oh.
Now lets assume the glass may have some imperfections. A quick google shows that nickel-sulfide inclusions can be found in 1-2/100,000 6 mm tempered glass panes. An inclusion can result in localized tensile stress as high as 860 MPa (Glass Breakage – Nickel Sulfide Inclusions, n.d.), resulting in microfractures that are easily recognizable. These are primarily a concern in tension zones (say, the center of a pane for a long, starting to bow out aquarium).
Repeated microfractures can cause the weakening of a pane of glass. While I was unable to find the values of strength drop, a microfracture review with repeated loads found that cracks in glass follow progressive stages, with cracks formed by the procedure continuing to produce lateral cracks for hours afterwards (Zakiev et al., 2020). Overall, initiation and propagation of cracks are accelerated by the presence of water (a concern for those of us who scratch up glass with hardscape from the inside).
Minimizing the impacts of sound waves Outside the blast radius, one can assume that waves propagate at the speed of sound, approximately 343 m/s. One can think of either reflecting the wave, or diffusing it rapidly over a short distance prior to the delicate glass. To destroy the incoming waves, it would be necessary generate acoustic waves constantly, in hopes that they would cancel out the incoming waves by means of perfect destruction. Alternatively, one can apply an acoustic panel, which purportedly absorbs sound by conversion into heat energy. I found that a 1-inch foam acoustic panel has a noise reduction coefficient of 0.4 on average (where 0.0 represents a surface that completely reflects sound), though I have not read the ASTM to review the power levels they evaluate (ASTM C423-23). Generally, the more porosity for a given area, the more reflections can take place in a short amount of time. Alternatively, one can diffuse the sound waves by strategically placing a number of flat panels in an attempt to reflect and stagger the effects. An interesting thought would be to place a curved reflector surrounding the aquarium, such that sound waves coming in from every direction would be reflected as evenly as possible.
Conclusions
Despite the very real threat of sonic booms occurring in certain places in the world, preliminary work shows that the failure of aquarium glass for hobbyists is likely to come from pre-existing damage, or repeated events. A single blowout for a relatively new, unstressed aquarium from a passing fighter jet appears unlikely (note that this is not advocating lack of caution!). However, points of failure include the silicone seams, and the aquarium is at greater risk if it has been exposed to prior stressors, thus unquantified. Diffusing or absorbing shockwaves may be possible, though the specific reductions in terms of energy translation and thereby impulsive pressure waves are not quantified in this work. Subsequent studies modelling these specific effects are under consideration, as is generating the impulsive source directly, rather than use of a scaling law, and accounting for cumulative effects such as secondary shockwaves, and ground shaking.
ReVelle, D. O and Edwards, W. (2007). Stardust—An artificial, low-velocity “meteor” fall and recovery: 15 January 2006. Meteoritics & Planetary Science 42(2). pp. 271-299. DOI: 10.1111/J.1945-5100.2007.TB00232.X
Silber, E. A., Bowman, D. C., Carr, C. G., … (2024). Geophysical Observations of the 24 September 2023 OSIRIS-REx Sample Return Capsule Re-Entry. Accepted for publication in the Planetary Science Journal. DOI: 10.3847/PSJ/ad5b5e. arXiv: https://doi.org/10.48550/arXiv.2407.02420
Ceplecha, Z., Borovička, J., Graham, E. W. (1998). Meteor phenomena and bodies. Space Science Reviews 84(3-4). pp 327-471. DOI: 10.1023/A:1005069928850
ReVelle, D. O. (1976). On Meteor-Generated Infrasound. Journal of Geophysical Research 81(7). pp 1217-1230. DOI: 10.1029/JA081I007P01217
Zakiev, I., Gogotsi, G. A., Storchak, M., and Zakiev, V. (2020). Glass Fracture during Micro-Scratching. Surfaces 3(2). pp. 211-224. DOI: 10.3390/surfaces3020016
Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method – ASTM C423-23 (2023). https://www.astm.org/c0423-23.html. Retrieved Aug 9, 2024.
A hoya blooming to completion for me was a first! I’m not typically one for blooming plants, but this one promised dark purple flowers, and so I was intrigued. The plant was acquired with two sets of leaves back in 2023, and has since put out another 3 sets of leaves in the intervening time. That’s something like 150% growth! More importantly, during early May, a peduncle started forming. This signifies the potential the plant is starting to push out a cluster of flowers if it doesn’t “blast” off, like my linearis did last year. I was pretty excited to see these “black” blooms, but wasn’t holding my breath. Over the span of another two weeks, the blooms slowly got larger and showed their “waxiness”. I missed the moment where they unfurled, but I came back one day to full on flowers (Figs. 1 and 2).
Apr 21, 2024Apr 27, 2024Apr 28, 2024Figure 1. Left to Right, progression of hoya blooms over a week.
Figure 2. The flowers all open! Picture taken Apr 30, 2024. Also check out that cute olive jar it lives in. Surprisingly hasn’t shown any signs of needing a larger vessel yet! Yellowing is almost certainly from getting too much light.
Flower and Plant Review
The bloomed didn’t smell particularly strong, but there was a faint sweetness if I got very close. Admittedly, I didn’t think through the fact that this plant lived on a shelf, and the blooms were well below my face height while sitting. So to see the blooms, I had to either jam my face in at an awkward angle, or pull out the plant to admire. Anyhow, the plant bloomed, I was happy, but not entirely convinced it was worth the wait. The leaves aren’t particularly charming, and unless it’ll be regularly in bloom, it doesn’t do much as a décor piece. It also made a mess after the pollination, leaving behind nectar blobs that had dripped off onto the shelf. A minor amount of drippiness can be seen in Figure 4.
Figure 3. Hoya blooms early in the morning on May 2, 2024 at 5:09 AM. The nectar can be seem in where the fuzzy petals are slightly darker.
The Response
With that in mind (the plant being rather boring), I tried to go to bed. At some absurd hour, I decided that it might be worthwhile pulling out the information I had on trying to pollinate the plant. I vaguely recalled that I had downloaded a few articles on the procedure, but being in bed, it was easiest to pull out my phone. Here are the two sites I landed on:
I also found a less than useful, but often looked at YouTube resource for pollination and a Reddit thread wishing the poster luck: https://www.reddit.com/r/hoyas/comments/ghng1f/pollinating_hoya_blooms/. The main issue I found was somewhat low resolution images and unclear arrow directions in the diagrams. Even though everything was labelled, looking up the respective parts of the hoya flower across different flower types was quite difficult. Here are the steps with the best interpretation I could make.
Identify the respective components. Hoya blooms tend to be in clusters, though some form single blooms. The flowers are typically 5 sided, forming star patterns. To pollinate, the parts of interest are near the center of the flower, where activity takes place
Pick your weapon
Pull out the pollina by sliding along the surface slit, gently pushing down, hooking the dark joint (corpusculum), and lifting it out. The pollina consists of two pollinium attached by a corpusculum
Identify your target and hold your breath
Slide the pollina into and through the “stigmatic lock”, also known as the ”staminal slit”. The goal is to get the pollen in the pollina to contact the inner walls of the lock
Repeat
I reluctantly rolled out of bed after realizing I wouldn’t be able to sleep unless I tried the pollination out myself. From what I could tell, the goal is simply to readjust the location of the pollen source further up.I took some photos for reference (Fig. 4), then decided to also take the internet’s advice on repeated trials. I balanced juggling my phone, trying to read instructions, while trying to perform the procedure on a single cut flower (Fig. 5). If I could pollinate while it was stably fixed in place, then maybe I’d have an alright shot trying to balance a wobbling plant too.
Figure 4. May 5, 2024. Detailing on the flowers, they are quite dark! Also a fun back shot for more detail. The leaves have cute pink speckling.Figure 5. The test bloom. Isolated and slotted into the base of a terracota pot since that’s what I had on hand.
Procedure
There are “optimal” times for pollination, and I’m not sure the crack of dawn was it. I found it fairly difficult to get the insertion correct, despite this flower having a very simple and accessible structure. This could have been because it was 4:30 am and I was all bleary eyed, or I didn’t have the right tools. The internet recommends a cat whisker (I left mine behind), but I only had a horse hair on hand. I decided to stick with the fresh X-ACTO knife blade gave me the best balance between control and width after the horse hair proved itself too difficult to be used. (Figs. 6 and 7) Note, if you use a utility knife like I did, you’ll find that the flower also bleeds sap!
Horse hairX-ACTO bladeFigure 6. The weapons of choicePicking out the pollinaPost insertionFigure 7. Some snippets of the action.
The Result
In the end, I managed to repeat the procedure at least 3 times across most of the remaining flowers that were still attached to the main stem. One of the biggest issues I had were the pollinarium not wanting to remain in the lock. They would poke out a bit and I was reasonably confident that the probability for fertilization would be just about zero. Trying to insert things in also caused a lot of damage to both the receptive and insertion components of the flower. Nontheless, I was hopeful.
I waited a few more weeks but the flowers all dropped and dried out. A fun experiment, and one I’ll likely try out again if I get the chance. Preferably at a different hour.
Figure 8. Dried up flowers a month later. You can see how plump the flowers used to be! This may be worth dissecting later to see whether or not the pollina vanished.
I’ve also made my own reference diagram I can look at and contribute!
Figure 9. Abstracted diagram for hoya pollination procedure. Find one pollina, remove via corpusculum, insert corpusculum in first through the stigmatic lock, push until pollium contact the inside of the lock. (It is entire possible I got the insertion direction wrong, but I can’t imagine it matters so long as contact is made!)
Next Steps
I might try to invert the shape of the pollina next time in case the pollen is on the inside of the wings rather than the outside edge. For this specific plant, it may also be worth waiting an extra day or two to pollinate, since the flowers lasted for quite a while, and I feel like they would naturally be more receptive when the nectar is more actively being produced.
Regrettably, I can’t validate the procedure I detailed because I’m writing this a month later, long after the flowers have dried and dropped off with absolutely no seed pod production. Maybe the sudden increased production in nectar caused the pollina to slide out? Maybe I should harvest some insect legs to try pollinating? Or perhaps self-seeding rates are simply very low to begin with?
Figure 10. A hopeful Hoya linearis bloom on the way? Check back in a month or so!
A very special event indeed, what a time to be on strike. As of writing this, I’m still making up some strike pay hours. Nonetheless, I was extremely fortunate to view totality at a relatively clear location some hours away from where I am normally situated.
I went equipped with:
eclipse glasses
sandwich materials and some chilled diet coke
a sweater
and a lot of patience
We managed to find a park with an available bench to have the pre-eclipse picnic, then started checking through the glasses periodically, trying to find when the first visible blip over the Sun would happen (I had forgotten the specific times, and didn’t feel like looking it up). Here are some photos I took during the progression (Fig. 1).
Figure 1. Eclipse progression from left to right, top to bottom. All images where taken with eclipse glasses over cellphone camera.
For the most part, I was taking images through my cellphone camera and the glasses. Some branches did get in the way to make it difficult, but it was a fun exercise.
I had a burst of inspiration halfway through the eclipse and pulled out the photometer on my cellphone, laying it flattish along the arm of the bench. It registered around 50k lux around the midway mark. I checked on this periodically, with the value falling off during cloud passage or shadowing (inference, at first I thought it was just the eclipse progressing quickly!). When totality neared, the radiance value plummeted to a few hundred, and dropped further to single digits.
A couple of days later, it occurred to me it might be interesting to plot those values and see what it might look like. On top of that, was there some way I could estimate the incoming flux based on first principles? How accurate were my readings from my phone in comparison to weather stations? Let’s say I didn’t get far, but here is what happened.
Here’s how I tried going about it. The first is getting the total incoming flux at the top of the atmosphere and how much is getting through the ground. I added some values from the typical incoming solar radiation and then some specific incidences at a nearby weather station. Clearly they were quite different from each other (Fig. 2). Nontheless, I also tried fitting the data points I took. I tried a few different curve fits and ended up with mildly ridiculous fits (Fig. 3). Intuitively, I had been expecting something like a sigmoid function to align well, though I received a suggestion for a gaussian fit to align with what we see from transits instead, which in retrospect, makes quite a bit of sense. However, this fell to the backburner and I didn’t get quite anywhere.
Figure 2. Nearby station data plotted over the 2 data points collected on site.Figure 3. Miscellaneous fits to the site collected data.
I don’t have much of a conclusion to this other than, a cellphone probably does not replace a pyrometer, and three data points does not make for a good fit.
Things can’t be that bad. I counted 17 baby shrimp!
– Elisa, February 2024
Prelude
Three-ish months ago (Nov 17, 2023), I set out on an adventure to build a living wall. I had just moved home, and I was thinking of ways to decorate my room and now office space. As it turns out, picture frames for 3 foot long posters are not as readily available at a budget price, even when shopping second hand. I opted for a project I had been wanting to try for a while, putting up my plants on wall. The rational was multi-fold.
Firstly, it has been a life long dream to have a living wall in my own space, with my preferred selection of plants. No fake moss. Secondly, it would take up space on the wall, and should be much cheaper than frames. Thirdly, if I could rig up an automated watering system, this would alleviate the need for leaving my plants unwatered and uncared for during long periods away, or asking someone else to take care of them. All of this sounded entirely sensible to me.
Act I: Making a Watering Wall
So, I sized it out. I knew I needed a waterproof support frame, and some sort of water permeable fabric. I wanted to add a watering system, so I decided to build the frame from PVC pipes, drill holes at the top, and pump water through one end. Dimensions were constrained by the largest garden/landscaping fabric I could find at a reasonable price, 3 feet across. I had been hoping for 5 by 5 feet, as I really wanted it to fill up the space in Zoom calls, but we do what we can. I estimated the maximum head a pump would need to be able to push up to the top of the frame, and multiplied it out by the internal PVC dimensions (I went back and forth inner dimensions, and decided that ½ in pipe would be sturdy enough if I built a central cross feature in the frame). Some quick googling later, I figured I would need a pump that could allegedly do at least 10 ft of head from the main ½ in outlet. I came up with a few configurations, and decided it would make sense to pipe the water out bottom side of the frame.
My shopping list looked something like this:
2 10’ lengths of ½ in PVC pipe
5 T-joins
1 cross join
3 elbows
3’ width fabric, roll of
40 gph pump
Flexible hosing (to link the pump and frame) and connectors
PVC cement
Something to store water in, at least 3’ + a few inches wide to accommodate for the pump connector
I already had a saw and drill with various bits. I purchased the pump a day in advance to look at the outlets and what was needed to join the pump to the frame. Now it was off to Home Hardware. They didn’t have enough T-joins for ½ in pipe. Next step, Home Depot. The folks there were kind enough to ask what kind of project it was. As it turns out, white PVC pipes are necessary when dealing with potable water. For my use case though? Electrical conduit would do just fine at half the cost. Great! They were out of conduit in the dimensions I wanted, so I picked up the PVC connectors before heading on over to the RONA down the street. I finally found the conduit, ½ ‘’ ID and 3’ in length. I purchased 2 10’ lengths and wedged them cautiously into the car. At some point, a trip had been made to Canadian Tire to pick up a giant Rubbermaid tote. It was a ROUGHNECK, and claimed it wouldn’t crack in winter conditions. I had been hoping for a flat bottomed box or planter, but an internet search had revealed that most nicely formed boxes were capped at around 48 inches or less. No matter. I could figure it out later.
One night of staying up working on impromptu projects wasn’t enough (I had built a Corsi-Rosenthal box the previous night and spent far too long perfecting the box fan coverage around the corners). I sawed the pipes to length, using a 30 cm ruler as a guide, sanded the edges down with a rasp, and finished the edges with a coarse grit sand paper. I gingerly put all the pieces together with the connectors and flexed the frame. I felt like it would hold. I cemented the pieces together and let it cure outside. At this point, night had fallen and I took a break for dinner.
The cement had cured by the time I was done, so it was time to do a water test. Holes were drilled and the connectors added. At this point, I realized that the connection point to the frame sat belowthe frame, and not to the side like I had planned. But it was already cemented in. I figured it wasn’t a big deal. We filled a bucket with water, dropped the pump in, and turned it on. It worked! The disbelief on our faces belayed the lack of faith in my online water head calculation. But the drill spacing and flow rate worked perfectly to lift the water to the top of the frame, and distribute the outflow across the drill holes. Naturally, I had to move on to the next step, seeing if the flow would be enough to saturate the garden fabric.
I lugged the frame and the roll of fabric outside and started wrapping it tightly on the frame. I was doing this unsupervised and alone at this hour, and naturally ended up making some impromptu decisions in the dimming light. I decided to make the fabric wall by wrapping around the frame three times. After folding the frame in, I punched some holes through the fabric with the tip of a pair of scissors right by the top of the frame, and zip-tied it in with some spare zip-ties I had found in my bag after some field work. I tested again with water. Slowly but surely, the compressed fabric against the outlet holes of the frame began to take up water. Holding the frame perpendicular to the ground, water dripped through the fabric instead of the air space between the front and back.
I chucked the whole thing into the Rubbermaid tote (Fig. 1). Job well done, I thought.
Figure 1. Garden fabric wound around a PVC frame, then chucked into a tote.
Intermission: Watering Wall to Living Wall
I lack some clarity on the timeline for the next few parts, but I eventually stitched a few pockets made of cut rectangles from the fabric using fishing line to the “front” side of the wall. I stuffed the pockets with a lower layer of LECA, placed some plant cuttings in, and secured them with more LECA. The tote had been hauled up to my room and propped up against a wall. It had been filled with well over 20 gallons of water, enough to avoid running the pump dry. Over the next few days, I would plug in the pump to “water” my plants (Fig. 2). One issue I knew I would be running into was the stability of the frame. I wanted it to be vertical. With it leaned up against a real wall, there were certain to be mold issues and water damage.
Figure 2. Putting plants on the “wall”. Darkened areas are saturated with water. Notice that the tote’s lid is behind the wall, this was preventing the wet plant wall from contacting the drywall.
I tried a few different configurations, including filling the tote with 1 gal bottles to brace it (and limit the total water volume in case the tote cracked), and propping it up on an overturned planted when the awkward angle from the pump connector started really bothering me (Fig. 3). I was hoping that eventually I could get some 3D printed supports in.
Figure 3. With some added lighting, hanging plants, and sneaking gallon bottles propping up the wall.
Act II: Water Quality and the Clean-up Crew
A week later, I discovered that the water in the tote was… unpleasant. It was time to cycle it out. I ran into my first issue here. The frame was now waterlogged and quite unwieldy. Hauling a flexible plastic tote filled with ~80 L of water was also not quite practical (Fig. 4). This resulted in a very silly, slow water drain by repeatedly filling gallon bottles and dumping them out into the bathroom while the frame had been lugged into a bathtub while this was happening. This would not do.
Figure 4. A messy room with plants, and a rubbermaid tote full of water and gallon bottles. Those are rock samples in the ziploc bags…
I mulled it over for the next week or so. The second time I had to do the tote lugging and gallon bottle juggling, I decided that I was over it. Either I could disassemble the wall for a later date, or get something to clean up my water. The plants were doing great though, and I didn’t want to disturb them. So I thought, shrimp! Shrimp would be my solution.
Some quick googling later, I found that Amano shrimp were great algae eaters and detritivores, quickly breaking down plant matter. I had decaying leaves in the tote already, and a filter in the pump. Surely it would work out! (For those who do not know, ammonia is a product of decaying matter, and is highly toxic to various organisms. Denitrifying bacteria convert ammonia to nitrite – also toxic, and then to nitrate – less toxic). Just in case though, I would throw in some extra dead leaves and wait another week. The time line becomes even more blurred here. Did I buy the freshwater test kit then? Or did I wait until I first got my shrimp?
I recall being excited to find an aquatics shop in London when I was visiting. We made a quick stop. I asked for 3 Amano shrimp, a marimo moss ball, water wisteria, some pellet fish food in case there wasn’t anything to eat for the shrimp, as I didn’t have any algal issues. I was very tempted to get a few guppies, as I recalled them to be easy to take care of based on a few conversations I had had with a friend, but I decided to take it slow.
I brought the shrimp home, added a mesh beg to my pump to block the inflow of water, and I slowly released them into the tank, thinking that any beneficial bacteria that road along in the water might help. Over the next few days, the shrimp chomped away at the debris building up on the moss ball, and hid under various 3D printed benchys (Fig. 5) scattered throughout the water. All was good (Fig. 6).
Figure 5. Example of a Benchy – The jolly 3D printing tortune test. Did you know that benchys are top heavy? All of them flipped in the water. The shrimp enjoyed hiding underneath them until duckweed and other aquatic plants got introduced.Figure 6. Amano hanging out on an upside down benchy next to some floating plants.
I instantly fell in love with the little shrimp clomping around, and decided perhaps I could get a few more. After all, amanos were nearly clear in colour, and I could never find them in the tub. I went and visited a shop I had originally wanted to go to (they were closed for unknown reasons), and explained my situation. They confirmed that I wasn’t really planning on breeding, so amanos, plus whatever fun coloured shrimp I wanted would probably work. This time I ended up with 3 amanos, 3 painted fire reds (neocaridina), and 3 guppies.The red shrimp were on sale, so that made the decision fairly easy for me. The guppies were selected at a ratio of 2:1 female to male, to distribute the male attention between the fish.
This is around the time when things started going wrong. The new shrimp seemed to be fine, but the old ones were listless and would curl up at the bottom of the tub. That was odd. I started doing 30% water changes each day, despite the lugging back and forth. I was testing the water parameters at this time, and saw a clear increase in…nitrite. This happened during a particularly busy time, and I let it run on for far too long. Two shrimp had passed away by the time I did my research on how to address the problems I was seeing. I purchased SeaChem Prime, Stability, and API’s QuickStart after trying to figure out which PetSmarts had both Prime and Stability. I later found out cheaper ways to access these products, but in the meantime, I was following instructions for dosing each day, while doing water changes. Things seemed to be improving other than the loss of 2 of the original shrimp. I chalked it up to the failure to acclimate.
Intermission: A Rescue Mission
Things were going well, so I finally decided it was time to rescue some of the lake minnows in the garage. I kept them separately in another tub for a couple of weeks before adding them into the large tote (Fig. 7).
Figure 7. Quarantine tub! The golden pothos is likely doing most of the work keeping the water clean.
Act III: Upgrading the Living Wall
The only issue I was having now, was the plant wall itself. With all the time I spent worrying about the living critters in the tote, I had neglected to figure out a solution for adjusting the wall so that it would stand up straight. I had to check on it daily to make sure it was stable, and was knocking around all sorts of things in the tub to do so. Now that things were stable-ish, it was time to upgrade. I had been regularly keeping an eye on aquariums for sale, both from major online retailers and second hand. The prices of a new aquarium were eye watering.
While searching for a reasonably priced aquarium, I also purchased an air pump and sponge filters. I had a feeling the fabric in the frame likely wasn’t doing as much filtration and supporting denitrifying bacteria like I had expected. This way I would have some additional oxygenation and an extra place for bacteria to grow, just in case the filter in the pump wasn’t doing the trick. I also added an additional piece of filter media into my water circulation pump to provide a far denser spongey material and prevent sucking up any shrimp.
Some weeks later… I got it! An aquarium! With a stand! (Did you know how expensive new aquarium stands are? I was looking at tool shelves as an alternative). It was a whopping 72 gallons. Since it was a second hand purchase, bringing it home was its own adventure. It was also immediately determined that it was far too big and would hold far too much water for any of us to feel comfortable with it on the second floor where I had the current setup. Rip my office living wall.
I set it up dry, gave the interior a good wipe down, and took a look at the top of the tank. Yep, as I expected, I would need to elevate the plant wall ABOVE the tank. As it turns out, all tanks with dimensions greater than 48 inches all come with a supporting brace across the top of the tank, presumably to relieve pressure on the glass outwards somehow. I had originally been planning on a support frame anyways, but this meant building a pretty high one, with significant pressure downwards on the glass.
I built the frame (Fig. 8). I’ll bypass the complications here, but it turns out there are multiple brand options when it comes to PVC pipe connectors that inset at different depths. I purchased some weight diffusing egg-crate. I boiled some gravel leftover from a backyard project and weighed it down. I wedged the frame support under the brace and onto the egg crate. I added water. I also purchased some Eco-Complete to weigh it down when it went on sale. There was a questionable trip that involved the back of a warehouse for that one.
Figure 8. Somewhat of a preview. Bits and bobs leftover from the frame building. It took two iterations to get the light on safely. The tank is a mess of random things. Fear not! I took the java fern out eventually.
I let it sit for a while, then transferred all the fish and shrimp over.
The End: Grand Plans
I had grand dreams of building an urban scape filled with miscellaneous ceramic houses from the thrift shops and letting them overgrow with moss, and a mesh “highway” that the shrimp could use to cross the tank, with a giant mountain on the other end. I knew it would take some time to find all the pieces if I wasn’t going to get anything new, or make the parts myself.
The End?
Everything worked like a dream. My shrimp were happily picking away at the substrate and the walls. My fish were swimming around and constantly looking for food. There were little algal growths happening, copepods were showing up, and my fish were starting to get white specks on their bodies.
Wait.
…my fish were starting to get white specks on their bodies???
The Next Adventure
Wherein several tank diseases rip through the aquarium, I acquire multiple tank syndrome, I find several other vendors, the plants start to settle in on the wall, my “budget” plant wall defies the budget, the fungas gnats return, the baby shrimp make their appearance, and I find a local aquatic plant dealer.
I recently was notified by a friend that an interesting article had dropped. Coffee and volcanoes! How exciting is that? I cracked open the article and was initially excited, then increasingly dismayed. Here is the article: Study: Why a spritz of water before grinding coffee yields less waste, tastier espresso. I found very little to be excited about on the first read through, and felt some internal panic welling up. This was for sure going to lead to some poorly thought out, widely spread content. Here is the paper for reference: Moisture-controlled triboelectrification during coffee grinding. All “quotes” are from the paper.
Background
For the past few years that I have been involved with grinding coffee at home and brewing specialty coffee while on a low budget. I have heard that adding in a few drops of water will reduce some of the static electricity in the process whereby the finer coffee grounds stick to the burrs and internals of the grinder. Personally I have never actually tried this, as I find the bits sticking to the surface to be quite useful in removing fines from my overall grind. I’ve just tapped off the fines afterwards and run a finger to dislodge the remainder in the grind receptacle. Seeing the article title, I thought, perhaps someone has finally quantified what the effective static reduction is like!
Seeing also the note about a volcanologist involved in the work, I was hopeful that the analogies would prove meaningful. I read through the article as it meandered along in some of the past work from the lab and found that they had identified two general factors contributing to the charged particles. The article does a reasonable job summarizing the paper, in that the team tested a number of variables and collected a slew of data. This part was surprising. The paper was written such that a regular audience could parse the work and the writers at Ars Technica could summarize each segment. I then took a look at the paper.
Matter
The highlights on the site are fairly straightforward, but the print version is confusing. The paper opens up with what is presumably a visual abstract with some key words overlain an image of some ground coffee on some unidentified mechanism. There is a brief background on the sources of charge (fracture and friction), with reference to some industrial interest in further studies on surprise charge. The authors claim to address three things: coffee parameters affect charge, demonstrating most of the charge is from the fracturing process, and charge is also dependent on moisture content. The introduction ends off with
“In the context of both understanding the fundamentals of triboelectrification and bolstering our efforts toward brewing more reproducible and sustainable coffee, this article offers strategies to control the charging of coffee particles and posits opportunities therefrom.”
The Results and Discussion section broke down those three aspects as follows
Charge parameters. They demonstrate that beans are charged via contact with typical coffee setup materials. It is unclear why they use the Starbucks Blonde Roast (blend) here. They then claim that coffee must be ground, typically to grain size of 100 nm to 2 mm. I was unable to find their reference here, as I usually grind coarser for a French press. Perhaps it is a reference to espresso grinds only. They skip ahead to state that finer grind sizes resulted in aggregates held together by electrostatic forces. They ground 1 g at a time and found both the net charge, and the charge distribution.
On origin. They used several Mexican coffees with different roasters and roast levels and found three different net polarities, “But those coffees were roasted by different roasters to different colors, and the data suggest, perhaps unsurprisingly, that origin alone does not dictate the polarity of charge.” I can confirm, this is unsurprising and the point on origin is not meaningful as one farm produces differently than the next, even if they are immediate neighbours.
They repeated this for 30 coffees and found a weak relationship between Agtron value (roast level) and charge. Instead, they pinpointed the 2% moisture content as the possible culprit (R-squared = 0.41). This runs counter to volcanic ash and an interesting point! It also indicates that they were able to measure moisture content of these coffees.
Two suggestions were provided. First, dark roast tends to be more brittle, and more associated with negative charge. The second, is that water content plays a role.
The distribution of negative particles is skewed towards fines and “boulders”. I did not get the same interpretation from the selected figures in the paper. In one of the images, the negative charge has a greater peak in the larger grain size range, but in the other, the two peaks are quite similar. An allusion to ion scavenging is made here. To that note, I wonder what their target grind size was as they later explain different roasts resulted in different size distributions. However, I didn’t see a distribution for neutral grains.
Roast parameters on charge.
Moisture. They roasted a 12% moisture green bean to a variety of different final products. They repeated for a 9% moisture green bean and found that the roast parameters were more important than the initial product moisture content for overall charge to mass ratio. The final moisture of the roasts fell between 1 – 3%.
Grind size. They used a different set of coffees from the moisture test, showing two coffees with net positive/negative charge and found that finer grinds correlated to higher charges. They also did a test using the same grind size across 13 coffees and showed darker roasts typically resulted in smaller mean diameter and more negative charge. “Figure 4C offers one explanation as to why darker coffees may yield slower espresso shots for the same brew parameters. It may not only be the increased volatile content but also the reduced bed permeability.” That is, lower grain size from the same grind is pulling slower shots. Note that your barista should be aware of the properties of their coffee beans that day, and should have each roast dialed in for the day. Because of the grind size difference with the roast levels, they repeated the experiment such that the same size distributions were had for each roast. They still found that negative charges correlated more strongly with darker roasts
Granular mechanisms. This targets the question of, how does the grind mechanism contribute to electrification? The authors pre-ground the coffee and then put it back through to evaluate the effects of frictional charging from grind interactions and coffee/grinder contact. There was about a 90% reduction in charge after testing on seven coffees by passing through a larger grind setting. Presumably they neutralized the coffee grounds prior to regrinding.
Addition of water. “Anecdotally, baristas have observed that the incorporation of small amounts of liquid water onto the whole-bean coffee prior to grinding results in seemingly reduced charging. In our hands, it also resulted in near-zero grounds being retained by the grinder, an observation that has implications for reducing waste and increasing quality of beverages. Perhaps we will revisit this in a future study, but for now, we are more interested in whether the addition of water neutralizes the effects of fracto- and triboelectrification or modulates particle aggregation via capillary forces.”
They found that humidity affected the charge once relative humidity was greater than 60%.
For seven coffees, they progressively added more water. Increase in water addition took place between 25 – 40% RH. They found that water content of 20 ul/g resulted in close to 0 net charge on the grounds and suggested either a cooling effect, or rapid ion transfer.
They also tested this with saline solutions to evaluate the effect of ion transfer. They found that the results were similar, so electron transfer in the dry case is more likely the cause of charging.
Here I find my major issue with the article. “To deduce whether the coffee particles were forming neutral aggregates”. This comes rather out of left field, perhaps they meant to create a new section? It seems that they were trying to answer what the net 0 charge consisted of, but never quite managed to say so.If this plays a significant role with volcanic ash, I feel that it would have helped the reader had they included more content in the Introduction. They found that the size distribution was improved with the addition of water, and found mostly neutral components in comparison to the “dry, field” grind result. The caption does not clarify what “field” and “no field” refer to, likely the method in which they sorted the bins. Water also reduces clumping.
Then they brewed some espresso using parameters that were unlike any of their prior parameters. 18.0 g dry mass coffee was used to produce 45.0 g liquid coffee extract, ground at setting 1.0, tamped at 196 N, and brewed using 94°C water, kept at 7 bar static water pressure with a 2-s pre-infusion. They found that without added water (unclear how much), the shot took less time and had a slightly lower TDS (total dissolved solids). The first drops enter the cup at the same time (~10s). They then fit a sigmoidal function to a hypothetical situation where the flow will achieve a constant and then looked at the flow rate for 3 samples of wet vs dry ground. “In other words, this is conclusive [bolding by me] evidence to suggest that dry-ground coffee is producing a bed with markedly more porous pathways.” They note that lower pH corresponds with higher S (more acidic coffee is less charged). They speculate on the role of internal moisture prior to roast.
That’s a lot! They went on to note that they made some assumptions about the burrs (in this case, their contribution is fixed, perhaps this is why they didn’t use other machines) and relate the Seebeck coefficient to the amount of charge from fracturing. They state that “Agtron number is proportional to the electronic band gap, both of which are reduced with darker roasts.” Without reference, so I will have to take their word for it. They related this to the Seebeck coefficient and oxidized organic molecules having low-laying orbitals. This seems to be a pretty big addition to the general knowledge of organic molecules, so I am surprised they did not highlight this more in the Introduction.
“Furthermore, light, medium, and dark coffees and their roast profiles can feature markedly different charging regimes, even for coffees with the same Agtron values. This highlights that modern roasting paradigms are highly artisanal and pose fundamental challenges for using commercially sourced coffee in academic settings.”
Alright. This feels like pandering.
“One could imagine the development of in-ground mineralization to make designer brewing water in situ without the risk of damaging boilers in espresso settings.”
I really don’t know where they were going here. Are they suggesting adding/removing heaps of salt and hardness to accommodate for water in advance and pulling shots with distilled? This is an interesting point I wish they elaborated upon.
Methods
I’ll highlight some interesting aspects I saw in the Methods section.
A pipette was used to introduce water onto whole-bean coffee, and the coffee was shaken in a sealed container to ensure homogeneous distribution.
Whole-bean coffee was stored in H2O-impermeable vacuum bags and kept at −20°C. The coffee was allowed to equilibrate to room temperature in the vacuum bag before grinding
I am curious to see how long the coffee was shaken to “ensure homogeneous distribution”. I also see that they didn’t comment on the effects of freezing the coffee prior to use, as freezing beans is quite controversial amongst coffee enthusiasts.
Notably, they did not provide a method to clean the grinder in between experiments, nor is there data indicating the mass loss during the process.
Commentary
“Many commercial coffee roasters treat their roast profiles as proprietary, and it is impossible to back calculate the precise profile from examination of only the roasted whole beans. There is academic value in standardizing roast profiles across the industry, thereby allowing for direct comparisons between coffees. But we are not advocating for this on the industrial scale, as that would sterilize an artisanal aspect of the industry. Instead, we developed our own profiles with the aim of isolating roast through the development of systematically “darker” coffees.”
This segment indicates that the authors care about the artistry of specialty coffee. Unfortunately, this theme runs through much of the paper and I found it to strongly influence how the paper was written. I then wonder, who was this paper written for?
As a consumer and coffee enthusiast, I am left with the following thoughts and questions
Lack of testing. Only ONE grinder was used during this test. I think they selected a sensible one if they were only going to use one, it’s reasonably accessible to different shops and the settings they used were straightforward. I do imagine perhaps there were complications justifying it on a budget (industry grinders are astoundingly expensive if there was no specific target goal for the research that served direct benefits). This is evident in James Hoffman’s video where he discusses the paper and interview with one of the authors, where he ends with a suggestion that at home brewers should fill in the gap.
Not understanding the difference between specialty crops and variability between farms that could be adjacent to each other. Given how many external individuals were involved in the work, this should have been caught early on.
Use of the standard dark/light roast ratings via Agtron was useful, but I wonder if there was the opportunity to develop a new standard for roast levels here. Perhaps based on water content before and after roasting?
Freezing? This changes how the coffee works. Why did they freeze things? Why did they not evaluate the effect of “resting” coffee? How fresh were the roasts? Why didn’t they roast more of their own sample? Why choose to use a number of different roasts? Was it just a PR stunt? Clearly they had collaborators, going back to the first thought, why not borrow a few grinders for controls?
I think there is the possibility that this work can be really extended and become useful for your average hobbyist. For example, nailing down the variable effect on extraction or charge scaled to average grind diameter and how variable the results can be if you have an even vs uneven grind
Who is this paper actually written for? The authors refer to the “artisanal process” a fair amount, and note some complications in terms of getting roast profiles. They also do not use grinders across the hobbyist market, nor test out burrs made of different materials (which should have a notable effect).
My thoughts as someone who attempts to write and share science via papers:
Absolute statements. The authors make a number of absolute statements that are not understood to be true, even by a regular audience. One such example is, “All coffee is ground”. Coffee beans are typically harvested, dried, then roasted to produce what the consumer sees as “coffee beans”. These can then be further processed by grinding to make a standard “coffee” drink, but can also be coated in chocolate, or have some of the volatiles extracted via CO2.
Lack of structured testing. Opportunistic testing makes sense when one is in the field, or has limited time/funding/equipment. The authors picked and chose one strand from each of the experiments to continue on with the next step, resulting in very little data. Perhaps there were limited controls on the experiment that they do not address.
Magical proposals. I am still baffled as to where the idea of “aggregates” comes from. This might be a matter of coming from a very different field, but if it is as intuitive as it seems, then it is surprising it wasn’t proposed earlier in discussion of volcanic ash. The role of neutral aggregates is not elaborated upon in terms of some of the other tests they did. Perhaps this lies somewhere in the realm of volcano science? The concept of aggregates was not surprising in and of itself, but it is unclear what fraction of aggregates were formed, and how they affected the final production when the aggregate ratio decreased. It’s worth noting here that I don’t possess an espresso grinder and perhaps all the “fines” that I’m thinking of are actually the espresso grind size, and the goal was to limit the loss of coffee. Which is a great target! Coffee prices are going up and grams can add up. That said, they could have been clearer in the introduction when mentioning potential industry impacts that this was one of their intentions.
Awareness. I think this article was actually great in terms of awareness for how one changes one parameter at a time when trying to perfect a coffee brew. The authors are potentially well on their way to changing how the standard espresso at a coffee shop is pulled, but given the sterilization of specialized coffee in recent years, perhaps their target was truly the at home tinkerer.
The only profound thing this article has demonstrated is how easy it is to blow up on the internet if you have the right connections or work on a topic that touches the lives of many. Does anyone remember how science indicated red wine was both good and bad for your health?
Sketchy Science Segment
As an additional Sketchy Science segment, here is my daily brew using a size 2 V60. This uses ~25 g of coffee (pure speculation on my part, it’s been a while since I checked) and ~380 mL of water. I use straight tap water with ~35 mg/L sodium in it with a CaCO3 hardness of 149 mg/L. I couldn’t find the pH on a public site, but a sample test with the Master Freshwater API Test kit indicates I have a water pH of ~7.4 straight from the tap. I have two kettles, one electronic to boil quickly, and one gooseneck for a controlled pour.
Boil 600 mL of water in an electric kettle to 100 deg C.
Grind coffee to around ~2 mm while heating water in kettle.
Transfer 400 mL water into a stovetop gooseneck kettle (this drops the temperature and bypasses the slow and inefficient heating on the stove). This typically drops my temperature to around 85 C.
Pre-wet filter so it sticks to the plastic V60 (I used to use a ceramic, but had too much heat loss from it). Dump excess water.
Pour ground coffee into the center of the wet filter, tap sides to even out the coffee bed. (At this stage, I find it most useful for fines to get stuck on the side of my grinder so very little ends up in my pour). Poke a shallow indent in the middle of the coffee bed
Gently pour from the gooseneck into the indent, and let the water slowly flow over, covering the coffee bed. This takes around 30 – 50 mL of water. Relatively fresh coffee should now “bloom” and release CO2 during this process. The goal is to get all of the grounds somewhat damp for the actual pour. Let sit for around 30 s.
Pour in a circular motion until you reach just over the half way mark of the size 2 filter. Give a gentle swirl in a clockwise motion to settle the agitated grounds so they funnel along the V60 grooves. Swirling counter to the groove direction will result in a lumpy bed.
While the water is still in motion, top off the water in a circular motion to ¾ up the filter. Let drain. This uses up around 200 mL
Walk away and futz around for a minute
Come back and do a second pour of around 125 – 150 mL. No swirling required. Let drain
Walk away and pack your bag for work
Pour ~100 mL. The water should be fairly slow to pass through now as the filter is getting clogged. Wait until you can see the sludge at the top and the filter is very slow to drip.
Optionally top off with the now ~40 – 50 deg C water and let drain. I heard in passing somewhere that the last little bit is actually the sweetest aspect. I can’t say I disagree when I decant out coffee earlier during the process.
Swirl the carafe gently to mix, then transfer into your preferred drinking vessel. Put a small amount aside in hopes that someone else will drink and appreciate your work.
Notes: I wanted to compare my water parameters to Third Wave Water, but I was unable find the information easily on their site. My guess is that it’s buried in a video somewhere. Since I first heard of their inception, they seem to have produced a number of water adjusters for multiple types of brews… I did find SCA water standards which their main product is inspired by and found Calcium Hardness 50 – 140 ppm, Alkalinity 40 – 70 ppm, pH 6 – 8 (huge range of acceptable pH, target of 7.0). My water hardness seems quite a bit higher than the standard, which I can certainly taste and experience when drinking water from the tap. https://sca.coffee/heritage-coffee-standards
Disclaimers: I have followed James Hoffman on YouTube for years, and I am really not a fan of his “science” work. I mostly appreciate what a big fan of coffee he is and usually only watch content when I am interested in the idea (clickbait titles). I typically end up disappointed when I see a basic Excel spreadsheet with no error bars or only one test, then avoid watching his content for several weeks in a row. I found his content on how to do coffee cuppings very interesting though, do check that out! I am told that the content is usually quite high quality in terms of robustness, so I must be lucking out. The commentary on AeroPress was quite interesting RE: industry insights however, and it’s still on my list of reading content to check out his Coffee Atlas. As always, check your sources folks. Clearly there is a lack of research in the realm of coffee, perhaps it’s time other scientists start branching out to bring in related ideas.
Conclusions
Here are some questions I would love answered, or perhaps answers are out there and I haven’t stumbled upon them yet.
Why do we break the crust during cupping? What is the actual goal here?
What is the perfect number of swirls and swirl motion to get a flat bed during a pourover if we consider grain size distribution, water temperature, and the standard V60 size 2 with Hario filters after the initial bloom?
Is there a perfect way to age a Coffee Sock? Surely the fabric and weave alter over time.
What is the most efficient way of cleaning a French Press without dumping grounds into the sink and flooding the garbage with water?
What’s up with Third Wave Water? What kind of testing did they participate in to develop their water conditioners?
We never did find out if the espresso was tastier at the end of the paper. Is it time to quantify taste preference in coffee for the average person vs the elitists?
I had the opportunity to do some field work for an extended period of time this summer. Logistics of field work, travel, insurance, and other field related prep work aside, I also had a large number of plants that needed to be taken care of. I had to make plans for said plants.
What ended up happening was roping in a few people to check in on my plants during my absence, and distributing them so no one person was saddled with watering 50 + plants with very particular needs. Instructions were, water when the soil looks and feels dry, approximately once every 10 days or so for the larger plants, and once a week for the smaller ones.
Had I been a little more prepared and had more time to plan, here are the things I would have done. The following information has been compiled from my past experience with leaving plants with roommates for just under 2 weeks, and typically being entirely absent during the holiday season. The good news is, we can test out these ideas soon! I’ve put off this post for so long that it aligns with my departure for 2 weeks, perfect to test out some of my ideas and rescue any plants that did not fare well in between. Its worth noting that there are some complicating factors that I didn’t account for, such as the change in seasonality, living in a drier environment than before, use of artificial lighting, plantlets recently released from their humid propagation boxes, blooms on the way, etc. And I might have pests. Woohoo.
Tl;dr
get plants in semi-hydroponics used to a higher water reservoir as to maximize fill before departure
stick plants in soil over large jar of water (without touching) as to provide moisture
Let’s talk about why I came up with these points. Plants require a few things to live (and grow). Water, light (also heat), and nutrients. Of these, water and light (Fig. 1) are the critical ones for indoor plants when it is not the growing season. Additionally, the balance between water and light is very important and ideally mimics the plant’s native environment or initial growing conditions. Nutrients are not considered for shorter term absences.
Figure 1. “Full spectrum light” as shown in the barrina T5 listing. x-axis shows wavelength, y-axis shows..a fraction of? Irradiance? Note the blue and red peaks, these are generally considered the important wavelengths for plant health and growth. Compare this to https://en.wikipedia.org/wiki/Sunlight#/media/File:Solar_spectrum_en.svg
Bottom humidity – fancy bottom watering
Watering without being present sounds like an easy thing to do. Just stick a bulb in or set up a drip system. This might work for some plants, but in my case, I predominantly have aroids and semi-succulents. These plants typically want to be watered in cycles of being fully soaked and then subsequently dried out until the next watering cycle. Nonetheless, most of my plants enjoy more moisture than the internet leads me to believe and typically live in a slightly more moisture rich environment in lieu of full desiccation. Thus, to maintain access to water without the ability to drench it from time to time (typically around 1 week’s time) can be a little difficult.
My solution is to stick all of my small pots over clean Classico mason jars after I use up all the sauce. The jars are filled about half way, and I pop the small nursery pots into the jar lid a couple of days after watering, so it maintains some moisture and will not fully dry out due to the nearly enclosed environment. This only works for my plants in pots of 2.5” diameter or smaller. For larger plants, self-watering pots are also an option, though I have typically found they are very finicky and require some calibration to prevent oversaturation of the base soil layer.
Hydroponics
Alternatively, I can provide endless amounts of water instead. This would be putting my plants into water directly, with or without additional media, but definitely not with soil. This method requires far more time to set up, but it is certainly doable. There are a few benefits of doing this. A deep water reservoir, precise control over nutrients, minimal pests… The trick is that it doesn’t work for every plant and it takes some time for plants previously living in soil to switch into water. Some I have cuttings fully growing out in just water, and some I have supported in a soil-less medium that wicks up water with strong root growth (this also adds aeration, very important to prevent a hypoxic environment!). The biggest complication with this method is cost – time and dollars. The second is that not all plants survive the transition, and it requires careful maintenance during that time.
For larger plants, transitioning into semi-hydro and filling up the jars as much as possible is ideal. If that is not an option, then the plant will simply not be watered during my absence. Plants in large containers tend to have more established root systems and reservoirs for instances of drought. Tropicals will not love this, but succulents will do just fine if they are large enough.
No sun or little sun
For the plants where I can’t set up water access via a large pool beneath the pot, I remove the water entirely. This leads to the plant missing a key ingredient for growth. In which case, perhaps the plant should not grow at all.
If there is no light, then there is no strong reason for water uptake. Most of my plants are suitable for “bright, indirect” sunlight. This is a cryptic statement that many a plant owner struggles with. What it tends to translate to is, most of my plants prefer as much sunlight as I can give them, so long as I bump them slowly into the sun. On the flip side, limiting sunlight will limit and slow growth. Less growth also means less water uptake and might set it off on a hibernation mode. Which is perfect if you can’t water your plants.
Grouping
Why group plants together? For context, my groupings are roughly: semi-succulent, semi-epiphytic, problem plants, and one-offs. These groupings are by water/light requirement, and care. The semi-succulents will need next to no care while I am gone. The semi-epiphytic plants and aroids would like some care. The problem plants need to be regularly checked on (these have pests, and I am not opposed to having them die-off entirely). And the one-offs are those that need to be watered, or left alone entirely. This just makes positioning my plants and making sure none get left out if there is someone checking in on them easier.
Survival of the fittest
Naturally, the plants might still be unhappy or die off while I’m gone. So what survives, survives. That’s a useful indicator for future trips what kinds of plants will do okay. In the chance I have to leave for an extended period of time again, then I’m all set with what did alright last time. Alternatively, if I really want plants around, cheap and robust plants are the way to go.
3+ weeks of travel
Things that actually happened during the field season: I split up some plants to pass along to others to take care of. At least one was on death’s door (it shriveled up, and the other similarly sad looking plant now has 1.5 leaves). I had a pet pass away during this time as well, I have no real thoughts on how to improve this situation for extended periods away other than living with someone else that is equally bonded to the animals. The rest of the plants are doing alright, though upon return, they did acquire some unwanted critters that were slowly killing them off.
Post field season thoughts: So that’s plants. What about the person travelling? I’ve been left with some thoughts after the last round of field work, and having just returned from a conference last week. One. Showers are nice. Two. I should start setting up a “recovery” station for myself when I return, especially if there is a big change in climate. Three. I want to find some time for myself to mull over what it means to be attached to various possessions, and how that affects me when I am absent or when I return after an extended period.
NEW: 2 week trial
Prepping for 2 weeks away, I’d like to avoid throwing my plants into hibernation. Stopping the growth of the young plants would simply lead to their death, or a tricky care situation on my return. Just about all of my smaller plants are in hydroponics or still suitable for a humid container. These will be under timed grow lights to compensate for the loss of sunlight with the change of seasons. The larger plants not in a reservoir will be going entirely unwatered, with two exceptions that are newer to my grouping of plants. Two smaller plants will also need to be watered during my absence, one is in the middle of slowly putting out flowers and requires the dry/wet cycle, and the other is entirely epiphytic in nature and does not possess functional roots. I have a few rooted cuttings, some will be staying in water, and some are being transitioned to semi-hydro and need to be topped off until the roots extend further. I was vaguely aware of needing to prepare them for my departure if I wanted healthy plants about 10 days pre-departure. During those 10 days, I purchased multiple grow lights and automatic timers, pulled out all the plants from propagation (except for one experimental box), informed my brother how to take care of my carnivorous plant (keep it flooded with rain water), and scattered hopefully live nematodes over all my potentially thrippy plants. I do still have some plants on campus, where they will be watered once during my absence. I may have written an entire spreadsheet with watering instructions and tips.
Expectations: All plants will be alive, and either slightly underwatered or overwatered when I get back. My calathea ornate (has spider mites currently and previously died down to a singular leaf) will likely go back to having one leaf. The corm only state oxalis may return from their hibernation and start putting out new leaves. The anthurium forgetii might be crispy. The propagations will not have made significant progress rooting. I will lose the hoya blooms on my linearis. If there are to be any casualties, I expect them to be amongst the newly propagated and the hoya I have had for weeks that have shown zero signs of growth (I think they had root rot before they even made it to my hands). Lastly, I might have aphids. I really hope this is not the case, but I have been side eyeing some of the leaf damage on my anthurium, and it is not looking promising.
Setup:
X2 barrina T5s – “full spectrum”
X1 barrina T5 – “full spectrum”
X1 sansi 15 W bulb – “full spectrum”
X1 barrina T5 (not shown)
X2 GE automatic timers with two outlets set to turn on from 7:30 am to 10:30 pm ET (not shown)
X3 misc coolermaster laptop fans (not shown)
4L of rainwater (not shown)
I purchased noma bulbs (8 W) sometime last year and also purchased a clamp lamp holder for it. I’ve been using it for nearly a year as a regular light bulb as well, and it has generally been focused on my carnivorous plants. I purchased the sansi bulb as an experiment when I moved home, with the intent of hanging them via pendant lamp bulb holders (since returned due to overheating). It now lives in the clamp lamp. All noma bulbs are currently inactive. They provided the lowest intensity light and had a tendency to heat up more than I would have liked. Once I find holders that are better at dissipating heat, they will likely make it back into regular use. I later purchased a set of 8 barrina T5s (yellow).
In the meantime, I have a vertical plant stand next to a window (Fig. 2). The plants on the stand above the window sill receive no additional artificial lighting other than those under the sansi bulb. There is one plant at a lower level that has heavy leaves, so it’s on the ground in case it topples. That one receives an off axis barrina light since it does not need high light intensity. These two are linked to one timer.
Figure 2. Light sources include the window, sansi light bulb (clamped onto plant stand), and barrina T5 (attached to the plant stand and standing vertically, LED lights are facing parallel to the stand, not towards the plant). Sampling of spectra were taken for the sansi light from the closest platform, from the “base” – flush to the platform, and incrementally upwards from the locations marked with an “x”. Sampling for the barrina T5 was done at a diagonal by placing a ruler on the plant pot and away from the light. Sampling for the window stool plants was taken behind the stool, ~3 inches above the stool. Sampling of spectra for the stingray plant was taken at the base of the plant.
There are two barrinas linked together in the “closet” area, with the lights generally facing downwards about 5 – 20 inches away from the plant tops (Fig. 3). Another one is linked to the same timer and is focused on my previously “bathroom” plants (not shown in images). There are three fans in the closet, since I spotted some fluffy mold growing in the three days I had been gone. Ew. That’s probably what I get for no airflow and using rain water that has been sitting in a bucket of decaying leaves.
Figure 3. Light sources include the window, and two barrina T5s hooked onto closet bars facing downwards. Not shown (and not relevant) is another barrina T5 closer to the ground. The forgetii sampling is marked by a downwards facing teardrop, with samples starting at the base of the pot moving upwards. The hoya linearis is in a hanging pot and is much closer to the barrina T5. Sampling started from the top of the pot upwards. The hoya cluster is indicated by a group of 6 pots and is quite a ways from both artificial and natural light (> 1 m). The window sill plants receive natural light.
Various other plants are scattered about, in the hopes that natural lighting and overflow from growlights will be sufficient. To get a baseline, I decided to borrow – with permission! – a couple of spectrometers from the lab covering the UV and NIR range, and a cosine corrector. Samples were taken between 2:40 pm to 3:15 pm ET at 100 ms per sample and averaging over 10 samples. What I should be expecting to see is a curve similar to that provided by the barrina T5 listing (Fig. 1).
It looks like the Sansi bulb is doing a lot of heavy lifting, even on the far side of the stand. The “full spectrum”-ness seems to be covered reasonably well, though it certainly is not a smooth slope as otherwise shown in the images. The “oneoffs” show the light coming in from a window on a cloudy day. Both the stingray alocasia and hoya cluster are quite far from the window (~2m and 1m respectively), but the hoya cluster may additionally be receiving some light from the barrinas in the closet. That said, you can see the fall off from the barrina lights if they are not angled correctly from the dragonscale alocasia readings. The window stool may also be receiving some light from the sansi bulb, and is located about 40 cm away from the window sill. Even at this distance, the light intensity falls off quite a bit in comparison to spectra taken at the window sill.
The spectra looks as it should, based on the marketing images for the barrina lights. Though it is worth pointing out the apparent fall off around the 570 nm wavelength may be a function of the spectrometer rather than a lack of light in that wavelength. We can say that the sansi light bulb did a better job of outputting in the relevant spectrum than the natural light right by the window sill. It also does not have the red wavelength “peak”, and is more focused towards the blue light. Natural light coming in from the windows falls off very quickly, but the results might be different had it been a sunny day outside.
Welcome to my first post! Here I tell you about one of the silly things that I get up to when I’m sick and don’t quite have the capacity to focus on regular work.
Disclaimer: I am by no means a medical professional. No advice is being offered in this article. This article is intended to be humorous and demonstrate some basic techniques to pull data from images.
Acknowledgements: My family for taking me in when I was feeling unwell and insisting I eat well during the bout of COVID I got. They also got extra tests for me when I wanted to be consistent about the materials I was using for this study.
Materials and Methods: COVID-10 Rapid Tests (Rapid Response Diagnostics, Rapid Response (R) COVID-19 Antigen Rapid Test Cassette for At Home use) retrieved from various Shopper’s Drug Mart pharmacy sections. 11 samples were taken. 2 blanks were discarded following calibration. Samples were taken every 24 hours with up to 5 hours difference from the 7 pm ET reference time. Figure 1 demonstrates the contents of each box of tests.
Figure 1. Back of the Rapid Response (R) COVID-19 Antigen Rapid Test Cassette. Image provides brief description of the purpose of the contents and an illustration of the contents of the kit. Included are 5 test cassettes, swabs, extraction buffer tubes, and waste bags. Instructions for Use are also included.
To create the sample, the provided swab was inserted into the right nostril until the swab encountered the back of the nose and swirled several times to collect mucosal liquid. The same swab was applied to the left nostril in the same manner. The collected fluid on the swab was then swirled into the pre-packaged test vial. The test vials (buffer extraction tubes) in all cases were vials with a foil seal, retaining the buffer. The buffer soaked into the swab was removed from the swab via pinching of the plastic tube as the swab is pulled out. Unlike previous iterations of the tests, the swab could be removed immediately after soaking and mixing of the fluids. The buffer vial had an attached lid with a nozzle. The lid was attached after the swab was removed and 3 drops were squeezed onto the sample plate. 10 minutes after the initial drops were applied, the sample result was observed. One red line next to the “C” symbol indicated that the test was functionally normally. One red line next to the “T” symbol indicated that the result was positive. No other anomalies indicated that the sample results were reasonably reliable. Detailed instructions can be found at btnx.com/covid19athome.
The tests were taken beginning on Oct 3, 2022 back when the test subject woke up with a fever. 2 samples were taken during the first 36 hours (midday 1, evening day 2). Both tests resulted in “negative” scores on the rapid tests. These tests are not included in the visual analysis of the COVID positivity progression and were used to calibrate expectations. The third test was taken in the evening of day 3 and resulted in a faintly positive score. Subsequent tests were taken in the evening each day. The tests were aligned each night and it was observed that while the fabric/wicking material of the samples were drying out, the intensity of the red lines remained similar to their initial conditions at the end of the 10 minute waiting period. Images of the collected tests were taken using a OnePlus8T+5G phone using the default camera settings. The lighting available for the image was a 3 panel white LED approximately 20 cm above the middle of the samples. The photos were taken after nightfall and with no other illumination sources.
The selected “best” image was cropped to only include the samples to reduce any external interference (Fig.2). As the image was taken with a relatively perpendicular shot, additional skew was not required for the image. Boxes where the reference line (C-line) and the test line (T-line) were selected. The RGB pixel values were extracted from the the boxes for the 10 samples that were aligned next to each other. The values from the C-line and the T-line were then compared to each other in a few different ways to demonstrate the progression of having COVID to testing negative.
Figure 2. Cropped image containing results of the COVID19 Rapid Tests as taken by a cellphone camera. The last two tests are negative (no visible reading in the T-line).
Results: The RGB values were selected in pixels in xy dimensions of x by y pixels. This resulted in 100 pixels in each box selection. Isolating only the R-value for the C-lines (which one would potentially expect to be the most useful) provided a clear pattern where the R value is lowest when the pixel includes the C-line. In retrospect, this should be fairly straightforward to understand as the “white” background pixel is created from high values of all RGB components (256).
A plot of the maximum RBG values is shown for each one of the C- and T-lines in Figure 3. A clear maximum value for the T-line can be seen from each RGB component from samples 5 and 6 with a steep fall-off towards a minimum value with sample 8. Figure 4 shows the “normalized” R values for the T-line based on the minimum R-value in each sample test and scaled by the minimum R-value from the C-line.
Figure 3. Minimum RGB values in the area for the C-line (circles) and T-line (triangles). The difference in value can potentially be attributed to unbalanced lighting.Figure 4. Normalized R-values for each sample (minimum R in T-line divided by minimum R in C-line).
Discussion: Visual inspection of the COVID19 Rapid Tests would suggest that there was a rapid increase in the “redness” of the T-line in the first 3 days, with a slow taper off. It is possible that the saturation of the red is actually quite similar from test to test, and it is the thickness of the T-line that varies. In such case, checking the contribution to the R-value is not a useful indicator of “positiviness”. Instead, the thickness of the lines should be considered. In addition, there were no redundant samples. Future studies should consider 3 rounds of swabbing and taking the average metric of each sample run.
Conclusions: A faint positive is still positive. COVID sucked, but I was fortunate enough to not lose my sense of smell for too long (likely a blocked nose). We shall see about long-COVID.
References: Me.
Editor 2: …
Supplementary Material: Images from homemade meals during this time are included in this section. Image S1 includes a noodle soup with noodles made from scratch (I think). Image S2 is a mysterious fried rice concoction.
Abstract ED 
