As useful as corrugated cardboard is, we generally don’t consider it to be a very sturdy material. The moment it’s exposed to moisture, it begins to fall apart, and it’s easily damaged even when kept dry. That said, there are ways to make corrugated cardboard a lot more durable, as demonstrated by the [NightHawkInLight]. Gluing multiple panels together so that the corrugation alternates by 90 degrees every other panel makes them more sturdy, with wheat paste (1:5 mixture of flour and water) recommended as adhesive.
Other tricks are folding over edges help to protect against damage, and integrating wood supports. Normal woodworking tools like saws can cut these glued-together panels. Adding the wheat paste to external surfaces can also protect against damage. By applying kindergarten papier-mâché skills, a custom outside layer can be made that can be sanded and painted for making furniture, etc.
Are robotaxis poised to be the Next Big Thing™ in North America? It seems so, at least according to Goldman Sachs, which issued a report this week stating that robotaxis have officially entered the commercialization phase of the hype cycle. That assessment appears to be based on an analysis of the total ride-sharing market, which encompasses services that are currently almost 100% reliant on meat-based drivers, such as Lyft and Uber, and is valued at $58 billion. Autonomous ride-hailing services like Waymo, which has a fleet of 1,500 robotaxis operating in several cities across the US, are included in that market but account for less than 1% of the total right now. But, Goldman projects that the market will burgeon to over $336 billion in the next five years, driven in large part by “hyperscaling” of autonomous vehicles.
[Bhuvanmakes] says that he has the simplest open source photobioreactor. Is it? Since it is the only photobioreactor we are aware of, we’ll assume that it is. According to the post, other designs are either difficult to recreate since they require PC boards, sensors, and significant coding.
This project uses no microcontroller, so it has no coding. It also has no sensors. The device is essentially an acrylic tube with an air pump and some LEDs.
As common as uranium is in the ground around us, the world’s oceans contain a thousand times more uranium (~4.5 billion tons) than can be mined today. This makes extracting uranium as well as other resources from seawater a very interesting proposition, albeit it one that requires finding a technological solution to not only filter out these highly diluted substances, but also do so in a way that’s economically viable. Now it seems that Chinese researchers have recently come tantalizingly close to achieving this goal.
The anode chemical reaction to extract uranium. (Credit: Wang et al., Nature Sustainability, 2025)
The used electrochemical method is described in the paper (gift link) by [Yanjing Wang] et al., as published in Nature Sustainability. The claimed recovery cost of up to 100% of the uranium in the seawater is approximately $83/kilogram, which would be much cheaper than previous methods and is within striking distance of current uranium spot prices at about $70 – 85.
Of course, the challenge is to scale up this lab-sized prototype into something more industrial-sized. What’s interesting about this low-voltage method is that the conversion of uranium oxide ions to solid uranium oxides occurs at both the anode and cathode unlike with previous electrochemical methods. The copper anode becomes part of the electrochemical process, with UO2 deposited on the cathode and U3O8 on the anode.
Among the reported performance statistics of this prototype are the ability to extract UO22+ ions from an NaCl solution at concentrations ranging from 1 – 50 ppm. At 20 ppm and in the presence of Cl– ions (as is typical in seawater), the extraction rate was about 100%, compared to ~9.1% for the adsorption method. All of this required only a cell voltage of 0.6 V with 50 mA current, while being highly uranium-selective. Copper pollution of the water is also prevented, as the dissolved copper from the anode was found on the cathode after testing.
The process was tested on actual seawater (East & South China Sea), with ten hours of operation resulting in a recovery rate of 100% and 85.3% respectively. With potential electrode optimizations suggested by the authors, this extraction method might prove to be a viable way to not only recover uranium from seawater, but also at uranium mining facilities and more.
White LED bulbs are commonplace in households by now, mostly due to their low power usage and high reliability. Crank up the light output enough and you do however get high temperatures and corresponding interesting failure modes. An example is the one demonstrated by the [electronupdate] channel on YouTube with a Philips MR16 LED spot that had developed a distinct purple light output.
The crumbling phosphor coating on top of the now exposed LEDs. (Credit: electronupdate, YouTube)
After popping off the front to expose the PCB with the LED packages, the fault seemed to be due to the phosphor on one of the four LEDs flaking off, exposing the individual 405 nm LEDs underneath. Generally, white LEDs are just UV or 405 nm (‘blue’) LEDs that have a phosphor coating on top that converts the emitted wavelength into broad band visible (white) or another specific wavelength, so this failure mode makes perfect sense.
After putting the PCB under a microscope and having a look at the failed and the other LED packages the crumbled phosphor on not just the one package became obvious, as the remaining three showed clear cracks in the phosphor coating. Whether due to the heat in these high-intensity spot lamps or just age, clearly over time these white LED packages become just bare LEDs without the phosphor coating. Ideally you could dab on some fresh phosphor, but likely the fix is to replace these LED packages every few years until the power supply in the bulb gives up the ghost.
If legend is to be believed, three disparate social forces in early 20th-century America – the temperance movement, the rise of car culture, and the Scots-Irish culture of the South – collided with unexpected results. The temperance movement managed to get Prohibition written into the Constitution, which rankled the rebellious spirit of the descendants of the Scots-Irish who settled the South. In response, some of them took to the backwoods with stills and sacks of corn, creating moonshine by the barrel for personal use and profit. And to avoid the consequences of this, they used their mechanical ingenuity to modify their Fords, Chevrolets, and Dodges to provide the speed needed to outrun the law.
Though that story may be somewhat apocryphal, at least one of those threads is still woven into the American story. The moonshiner’s hotrod morphed into NASCAR, one of the nation’s most-watched spectator sports, and informed much of the car culture of the 20th century in general. Unfortunately, that led in part to our current fossil fuel predicament and its attendant environmental consequences, which are now being addressed by replacing at least some of the gasoline we burn with the same “white lightning” those old moonshiners made. The cost-benefit analysis of ethanol as a fuel is open to debate, as is the wisdom of using food for motor fuel, but one thing’s for sure: turning corn into ethanol in industrially useful quantities isn’t easy, and it requires some Big Chemistry to get it done. Continue reading “Big Chemistry: Fuel Ethanol”→
Fabrication of uranium-based components via DLP. (Zanini et al., Advanced Functional Materials, 2024)
Within the nuclear sciences, including fuel production and nuclear medicine (radiopharmaceuticals), often specific isotopes have to be produced as efficiently as possible, or allow for the formation of (gaseous) fission products and improved cooling without compromising the fuel. Here having the target material possess an optimized 3D shape to increase surface area and safely expel gases during nuclear fission can be hugely beneficial, but producing these shapes in an efficient way is complicated. Here using photopolymer-based stereolithography (SLA) as recently demonstrated by [Alice Zanini] et al. with a research article in Advanced Functional Materials provides an interesting new method to accomplish these goals.
In what is essentially the same as what a hobbyist resin-based SLA printer does, the photopolymer here is composed of uranyl ions as the photoactive component along with carbon precursors, creating solid uranium dicarbide (UC2) structures upon exposure to UV light with subsequent sintering. Uranium-carbide is one of the alternatives being considered for today’s uranium ceramic fuels in fission reactors, with this method possibly providing a reasonable manufacturing method.
Uranium carbide is also used as one of the target materials in ISOL (isotope separation on-line) facilities like CERN’s ISOLDE, where having precise control over the molecular structure of the target could optimize isotope production. Ideally equivalent photocatalysts to uranyl can be found to create other optimized targets made of other isotopes as well, but as a demonstration of how SLA (DLP or otherwise) stands to transform the nuclear sciences and industries.
