For how crucial whales have been for humanity, from their harvest for meat and oil to their future use of saving the world from a space probe, humans knew very little about them until surprisingly recently. Most people, even in Herman Melville’s time, considered whales to be fish, and it wasn’t until humans went looking for submarines in the mid-1900s that we started to understand the complexities of their songs. And you don’t have to be a submarine pilot to listen now, either; all you need is something like these homemade hydraphones.
Science1248 Articles
Why Chopped Carbon Fiber In FDM Prints Is A Contaminant
A lot of claims have been made about the purported benefits of adding chopped carbon fiber to FDM filaments, but how many of these claims are actually true? In the case of PLA at least, the [I built a thing] channel on YouTube makes a convincing case that for PLA filament, the presence of chopped CF can be considered a contaminant that weakens the part.
Using the facilities of the University of Basel for its advanced imaging gear, the PLA-CF parts were subjected to both scanning electron microscope (SEM) and Micro CT imaging. The SEM images were performed on the fracture surfaces of parts that were snapped to see what this revealed about the internal structure. From this, it becomes apparent that the chopped fibers distribute themselves both inside and between the layers, with no significant adherence between the PLA polymer and the CF. There is also evidence for voids created by the presence of the CF.
To confirm this, an intact PLA-CF print was scanned using a Micro CT scanner over 13 hours. This confirmed the SEM findings, in that the voids were clearly visible, as was the lack of integration of the CF into the polymer. This latter point shouldn’t be surprising, as the thermal coefficient of PLA is much higher than that of the roughly zero-to-negative of CF. This translates into a cooling PLA part shrinking around the CF, thus creating the voids.
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Building A Multi-Channel Pipette For Parallel Experimentation
One major reason for the high cost of developing new drugs and other chemicals is the sheer number of experiments involved; designing a single new drug can require synthesizing and testing hundreds or thousands of chemicals, and a promising compound will go through many stages of testing. At this scale, simply performing sequential experiments is wasteful, and it’s better to run tens or hundreds of experiments in parallel. A multi-channel pipette makes this significantly simpler by collecting and dispensing liquid into many vessels at once, but they’re, unfortunately, expensive. [Triggy], however, wanted to run his own experiments, so he built his own 96-channel multi-pipette for a fiftieth of the professional price.
The dispensing mechanism is built around an eight-by-twelve grid of syringes, which are held in place by one plate and have their plungers mounted to another plate, which is actuated by four stepper motors. The whole syringe mechanism needed to move vertically to let a multi-well plate be placed under the tips, so the lower plate is mounted to a set of parallel levers and gears. When [Triggy] manually lifts the lever, it raises the syringes and lets him insert or remove the multi-well. An aluminium extrusion frame encloses the entire mechanism, and some heat-shrink tubing lets pipette tips fit on the syringes.
[Triggy] had no particularly good way to test the multi-pipette’s accuracy, but the tests he could run indicated no problems. As a demonstration, he 3D-printed two plates with parallel channels, then filled the channels with different concentrations of watercolors. When the multi-pipette picked up water from each channel plate and combined them in the multi-well, it produced a smooth color gradient between the different wells. Similarly, the multi-pipette could let someone test 96 small variations on a single experiment at once. [Triggy]’s final cost was about $300, compared to $18,000 for a professional machine, though it’s worth considering the other reason medical development is expensive: precision and certifications. This machine was designed for home experiments and would require extensive testing before relying on it for anything critical.
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Improving The Cloud Chamber
Want to visualize radioactive particles? You don’t need a boatload of lab equipment. Just a cloud chamber. And [Curious Scientist] is showing off an improved miniature cloud chamber that is easy to replicate using a 3D printer and common components.
The build uses a Peltier module, a CPU cooler, an aluminum plate, thermal paste, and headlight film. The high voltage comes from a sacrificed mosquito swatter. The power input for the whole system is any 12V supply.
The cloud chamber was high tech back in 1911 when physicist Charles T. R. Wilson made ionizing radiation visible by creating trails of tiny liquid droplets in a supersaturated vapor of alcohol or water. Charged particles pass through, leaving visible condensation trails.
Neutrino Transmutation Observed For The First Time
Once upon a time, transmutation of the elements was a really big deal. Alchemists drove their patrons near to bankruptcy chasing the philosopher’s stone to no avail, but at least we got chemistry out of it. Nowadays, anyone with a neutron source can do some spicy transmutation. Or, if you happen to have a twelve meter sphere of liquid scintillator two kilometers underground, you can just wait a few years and let neutrinos do it for you. That’s what apparently happened at SNO+, the experiment formally known as Sudbury Neutrino Observatory, as announced recently.
The scinillator already lights up when struck by neutrinos, much as the heavy water in the original SNO experiment did. It will also light up, with a different energy peak, if a nitrogen-13 atom happens to decay. Except there’s no nitrogen-13 in that tank — it has a half life of about 10 minutes. So whenever a the characteristic scintillation of a neutrino event is followed shortly by a N-13 decay flash, the logical conclusion is that some of the carbon-13 in the liquid scintillator has been transmuted to that particular isotope of nitrogen.
That’s not unexpected; it’s an interaction that’s accounted for in the models. We’ve just never seen it before, because, well. Neutrinos. They’re called “ghost particles” for a reason. Their interaction cross-section is absurdly low, so they are able to pass through matter completely unimpeded most of the time. That’s why the SNO was built 2 KM underground in Sudbury’s Creighton Mine: the neutrinos could reach it, but very few cosmic rays and no surface-level radiation can. “Most of the time” is key here, though: with enough liquid scintillator — SNO+ has 780 tonnes of the stuff — eventually you’re bound to have some collisions.
Capturing this interaction was made even more difficult considering that it requires C-13, not the regular C-12 that the vast majority of the carbon in the scintillator fluid is made of. The abundance of carbon-13 is about 1%, which should hold for the stuff in SNO+ as well since no effort was made to enrich the detector. It’s no wonder that this discovery has taken a few years since SNO+ started in 2022 to gain statistical significance.
The full paper is on ArXiv, if you care to take a gander. We’ve reported on SNO+ before, like when they used pure water to detect reactor neutrinos while they were waiting for the scintillator to be ready. As impressive as it may be, it’s worth noting that SNO is no longer the largest neutrino detector of its kind.
Germanium Semiconductor Made Superconductor By Gallium Doping
Over on ScienceDaily we learn that an international team of scientists have turned a common semiconductor germanium into a superconductor.
Researchers have been able to make the semiconductor germanium superconductive for the first time by incorporating gallium into its crystal lattice through the process of molecular-beam epitaxy (MBE). MBE is the same process which is used in the manufacture of semiconductor devices such as diodes and MOSFETs and it involves carefully growing crystal lattice in layers atop a substrate.
When the germanium is doped with gallium the crystalline structure, though weakened, is preserved. This allows for the structure to become superconducting when its temperature is reduced to 3.5 Kelvin. Read all about it in the team’s paper here (PDF).
It is of course wonderful that our material science capabilities continue to advance, but the breakthrough we’re really looking forward to is room-temperature superconductors, and we’re not there yet. If you’re interested in progress in superconductors you might like to read about Floquet Majorana Fermions which we covered earlier this year.
The Lethal Danger Of Combining Welding And Brake Cleaner
With the availability of increasingly cheaper equipment, welding has become far more accessible these days. While this is definitely a plus, it also comes with the elephant-sized asterisk that as with any tool you absolutely must take into account basic safety precautions for yourself and others. This extends to the way you prepare metal for welding, with [Dr. Bernard], AKA [ChubbyEmu] recently joining forces with [styropyro] to highlight the risks of cleaning metal with brake cleaner prior to welding.
Much like with common household chemicals used for cleaning, such as bleach and ammonia, improper use of these can produce e.g. chlorine gas, which while harmful is generally not lethal. Things get much more serious with brake cleaner, containing tetrachloroethylene. As explained in the video, getting brake cleaner on a rusty part to clean it and then exposing it to the intensive energies of the welding process suffices to create phosgene.
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