While fluid dynamics sounds like a dull topic, SoapFilmScope promises to make it fun by using your cell phone to observe the interactions between sound waves and liquid membranes. You can make your own with some PVC pipe, some 3D-printed attachments, a speaker, and a few other odds and ends.
If your PVC pipe doesn’t match [DaniloR29’s] exactly, no problem. The files are in OpenSCAD so you can easily change them to suit your needs. One end of the PVC tee dips into soap solution to form a film — think like a soap bubble before you blow it out of the bubble wand. The other ends have the speaker and the cell phone camera.
Science and engineering usually create consistent results. Generally, when you figure out how to make something, you can repeat that at will to make more of something. But what if, one day, you ran the same process, and got different results? You double-checked, and triple-checked, and you kept ending up with a different end product instead?
Perhaps it wasn’t the process that changed, but the environment? Or physics itself? Enter the scary world of disappearing polymorphs.
Could carbon fiber inflict the same kind of damage on the human body as asbestos? That’s the question which [Nathan] found himself struggling with after taking a look at carbon fiber-reinforced filament under a microscope, revealing a sight that brings to mind fibrous asbestos samples. Considering the absolutely horrifying impact that asbestos exposure can have, this is a totally pertinent question to ask. Fortunately, scientific studies have already been performed on this topic.
Example SEM and TEM images of the released particles following the rupture of CFRP cables in the tensile strength test. (Credit: Jing Wang et al, Journal of Nanobiotechnology, 2017)
While [Nathan] demonstrated that the small lengths of carbon fiber (CF) contained in some FDM filaments love to get stuck in your skin and remain there even after washing one’s hands repeatedly, the aspect that makes asbestos such a hazard is that the mineral fibers are easily respirable due to their size. It is this property which allows asbestos fibers to nestle deep inside the lungs, where they pierce cell membranes and cause sustained inflammation, DNA damage and all too often lung cancer or worse.
Clearly, the 0.5 to 1 mm sized CF strands in FDM filaments aren’t easily inhaled, but as described by [Jing Wang] and colleagues in a 2017 Journal of Nanobiotechnology paper, CF can easily shatter into smaller, sharper fragments through mechanical operations (cutting, sanding, etc.) which can be respirable. It is thus damaged carbon fiber, whether from CF reinforced thermal polymers or other CF-containing materials, that poses a potential health risk. This is not unlike asbestos — which when stable in-situ poses no risk, but can create respirable clouds of fibers when disturbed. When handling CF-containing materials, especially for processing, wearing an effective respirator (at least N95/P2) that is rated for filtering out asbestos fibers would thus seem to be a wise precaution.
The treacherous aspect of asbestos and kin is that diseases like lung cancer and mesothelioma are not immediately noticeable after exposure, but can take decades to develop. In the case of mesothelioma, this can be between 15 and 30 years after exposure, so protecting yourself today with a good respirator is the only way you can be relatively certain that you will not be cursing your overconfident young self by that time.
Implantable electrodes for the (human) brain have been around for a many decades in the form of Utah arrays and kin, but these tend to be made out of metal, which can cause issues when stimulating the surrounding neurons with an induced current. This is due to faradaic processes between the metal probe and an electrolyte (i.e. the cerebrospinal fluid). Over time this can result in insulating deposits forming on the probe’s surface, reducing their effectiveness.
Now a company called InBrain claims to have cracked making electrodes out of graphene, following a series of tests on non-human test subjects. Unlike metal probes, these carbon-based probes should be significantly more biocompatible even when used for brain stimulation as with the target goal of treating the symptoms associated with Alzheimer’s.
During the upcoming first phase human subjects would have these implants installed where they would monitor brain activity in Alzheimer’s patients, to gauge how well their medication is helping with the symptoms like tremors. Later these devices would provide deep-brain stimulation, purportedly more efficiently than similar therapies in use today. The FDA was impressed enough at least to give it the ‘breakthrough device’ designation, though it is hard to wade through the marketing hype to get a clear picture of the technology in question.
In their most recently published paper (preprint) in Nature Nanotechnology, [Calia] and colleagues describe flexible graphene depth neural probes (gDNP) which appear to be what is being talked about. These gDNP are used in the experiment to simultaneously record infraslow (<0.1 Hz) and higher frequencies, a feat which metal microelectrodes are claimed to struggle with.
Although few details are available right now, we welcome any brain microelectrode array improvements, as they are incredibly important for many types of medical therapies and research.
If you’ve ever watched Predator, you’ve noted the tactical advantage granted to the alien warrior by its heat vision. Indeed, even with otherwise solid camoflauge, Dutch and his squad ended up very much the hunted.
And yet, back in reality, it seems the prey might be the one with the ability to sense in the infrared spectrum. Research has now revealed this unique ability may all be down to the hairs on the back of some of the smallest mammals.
We’ve all been there — you forgot your lunch, but there are AC outlets galore. Wouldn’t it be so much simpler if you could just plug in like your phone? Don’t try it yet, but biologists have taken us one step further to being able to fuel ourselves on those sweet, sweet electrons.
Using an “electrobiological module” of 3-4 enzymes, the amusingly named AAA (acid/aldehyde ATP) cycle regenerates ATP in biological systems directly from electricity. The process takes place at -0.6 V vs a standard hydrogen electrode (SHE), and is compatible with biological transcription/translation processes like “RNA and protein synthesis from DNA.”
The process isn’t dependent on any membranes to foul or more complicated sets of enzymes making it ideal for in vitro synthetic biology since you don’t have to worry about keeping as many components in an ideal environment. We’re particularly interested in how this might apply to DNA computing which we keep being promised will someday be the best thing since the transistor.
Maybe in the future we’ll all jack in instead of eating our daily food pill? If this all seems like something you’ve heard of before, but in reverse, maybe you’re thinking of microbial fuel cells.
Can you weld wood? It seems like a silly question — if you throw a couple of pieces of oak on the welding table and whip out the TIG torch, you know nothing is going to happen. But as [Action Lab] shows us in the video below, welding wood is technically possible, if not very practical.
Since experiments like this sometimes try to stretch things a bit, it probably pays to define welding as a process that melts two materials at their interface and fuses them together as the molten material solidifies. That would seem to pose a problem for wood, which just burns when heated. But as [Action Lab] points out, it’s the volatile gases released from wood as it is heated that actually burn, and the natural polymers that are decomposed by the heat to release these gases have a glass transition temperature just like any other polymer. You just have to heat wood enough to reach that temperature without actually bursting the wood into flames.
His answer is one of the oldest technologies we have: rubbing two sticks together. By chucking a hardwood peg into a hand drill and spinning it into a slightly undersized hole in a stick of oak, he created enough heat and pressure to partially melt the polymers at the interface. When allowed to cool, the polymers fuse together, and voila! Welded wood. Cutting his welded wood along the joint reveals a thin layer of material that obviously underwent a phase change, so he dug into this phenomenon a bit and discovered research into melting and welding wood, which concludes that the melted material is primarily lignin, a phenolic biopolymer found in the cell walls of wood.
[Action Lab] follows up with an experiment where he heats bent wood in a vacuum chamber with a laser to lock the bend in place. The experiment was somewhat less convincing but got us thinking about other ways to exclude oxygen from the “weld pool,” such as flooding the area with argon. That’s exactly what’s done in TIG welding, after all. Continue reading “Welding Wood Is As Simple As Rubbing Two Sticks Together”→
