Switching From Desktop Linux To FreeBSD

June 29, 2025 by Maya Posch 44 Comments

People have been talking about switching from Windows to Linux since the 1990s, but in the world of open-source operating systems, there is much more variety than just the hundreds of flavors of Linux-based operating systems today. Take FreeBSD, for example. In a recent [GNULectures] video, we get to see a user’s attempt to switch from desktop Linux to desktop FreeBSD.

The interesting thing here is that both are similar and yet very different, mainly owing to their very different histories, with FreeBSD being a direct derivative of the original UNIX and its BSD derivative. One of the most significant differences is probably that Linux is just a kernel, with (usually) the GNU/Hurd userland glued on top of it to create GNU/Linux. GNU and BSD userland are similar, and yet different, with varying levels of POSIX support. This effectively means that FreeBSD is a singular OS with rather nice documentation (the FreeBSD handbook).

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Making Optical Glass From Ceran Stovetops

June 28, 2025 by Maya Posch 2 Comments

The Ceran discs, freshly cut from the old stovetop and awaiting polishing. (Credit: Huygens Optics)

Ceran is a name brand for a type of glass ceramic that has a very low coefficient of thermal expansion (CTE). This is useful for stovetops, but it is also a highly desirable property for optical glass. The natural question: Can an old ceramic stovetop be upcycled into something visually striking? This is the topic of the most recent video in [Huygens Optics]’s series on glass ceramics.

Interestingly, by baking sections of the Ceran glass ceramic for 10 minutes at 961 °C, the CTE can be lowered by another five times, from 0.5 ppm / °C to a mere 0.1 ppm / °C. Following baking, you need a lot of grinding and polishing to remove any warping, existing textures, and printing. After polishing with 220 grit by hand for a few minutes, most of these issues were fixed, but for subsequent polishing, you want to use a machine to get the required nanometer-level precision, as well as to survive the six to eight hours of polishing.

Following this final polishing, the discs were ground into mirrors for a Newtonian telescope. This raised a small issue of the Ceran being only 4 mm thick, which requires doubling up two of the discs using a very thin layer of epoxy. After careful drilling, dodging cracked glass, and more polishing, this produced the world’s first ceramic stovetop upcycled into a telescope. We think it was the first, anyway. All that’s left is to coat the discs with a more reflective coating and install them into a telescope frame, but even in their raw state, they show the potential of this kind of material.

If you decide to try this, and you’ve already cut up your stove, you might as well attack some kitchen bowls, too.

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PLA With PETG Core Filament Put To The Test

June 26, 2025 by Maya Posch 27 Comments

The Stronghero 3D hybrid PLA PETG filament, with visible PETG core. (Credit: My Tech Fun, YouTube)

Sometimes you see an FDM filament pop up that makes you do a triple-take because it doesn’t seem to make a lot of sense. This is the case with a hybrid PLA/PETG filament by Stronghero 3D that features a PETG core. This filament also intrigued [Dr. Igor Gaspar] who imported a spool from the US to have a poke at it to see why you’d want to combine these two filament materials.

According to the manufacturer, the PLA outside makes up 60% of the filament, with the rest being the PETG core. The PLA is supposed to shield the PETG from moisture, while adding more strength and weather resistance to the PLA after printing. Another interesting aspect is the multi-color look that this creates, and which [Igor]’s prints totally show. Finding the right temperatures for the bed and extruder was a challenge and took multiple tries with the Bambu Lab P1P including bed adhesion troubles.

As for the actual properties of this filament, the layer adhesion test showed it to be significantly worse than plain PLA or PETG when printed at extruder temperatures from 225 °C to 245 °C. When the shear stress is put on the material instead of the layer adhesion, the results are much better, while torque resistance is better than plain PETG. This is a pattern that repeats across impact and other tests, with PETG more brittle. Thermal deformation temperature is, unsurprisingly, between both materials, making this filament mostly a curiosity unless its properties work much better for your use case than a non-hybrid filament.

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Why Trijets Lost Against Twinjets

June 24, 2025 by Maya Posch 35 Comments

If you’re designing a new jet-powered airplane, one of the design considerations is the number of jet engines you will put on it. Over the course of history we have seen everywhere from a single engine, all the way up to four and beyond, with today airliners usually having two engines aside from the Boeing 747 and Airbus A380 has been largely phased out. Yet for a long time airliners featured three engines, which raises the question of why this configuration has mostly vanished now. This is the topic of a recent YouTube video by [Plane Curious], embedded below.

The Boeing 727, DC-10 and L-1011 TriStar are probably among the most well-known trijets, all being unveiled around the same time. The main reason for this was actually regulatory, as twin-engine designs were thought to be too unsafe for long flights across oceans, while quad-jet designs were too fuel-hungry. This remained the situation until newer jet engine designs that were more reliable and powerful, leading to new safety standards (ETOPS) that allowed twinjets to fly these longer routes as well. Consequently, the last passenger trijet – an MD-11 KLM flight – touched down in 2014.

Along with the engineering and maintenance challenges that come with having a tail-mounted jet engine, the era of trijets seem to have firmly come to an end, at least for commercial airliners.

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Building A Custom Paper Tape Punch Machine

June 23, 2025 by Maya Posch 14 Comments

The solenoid and punch side of the machine. {Credit: Simon Boak)

Although [Simon Boak] had no use for an automatic paper tape punch, this was one of those intrusive project thoughts that had to be put to rest. With not a lot of DIY projects to look at, the first step was to prototype a punch mechanism that would work reliably. This involved the machining of a block of aluminium with holes at the right locations for the punch (HSS rods) to push through and create holes into the paper without distortions. Next was to automate this process.

To drive the punches, 12V solenoids were selected, but using leverage to not require the solenoids to provide all the force directly. On the electronics side this then left designing a PCB with the solenoid drivers and an Arduino Nano-style board as the brains, all of which including the Arduino source can be found on GitHub. Much like with commercial tape punch machines, this unit receives the data stream via the serial port (and optional parallel port), with the pattern punched into the 1″ paper tape.

One issue was finding blank paper tape, for which [Simon] cut up rolls of thermal paper using a 3D-printed rig with appropriately installed sharp blades. This paper tape seems to work quite well so far, albeit with the compromise that due to the current drawn by each solenoid (~1.7A) only one solenoid gets activated at any time. This makes it slower than commercial punch machines.

Thanks to [Tim] for the tip.

Earth’s Oxygen Levels And Magnetic Field Strength Show Strong Correlation

June 23, 2025 by Maya Posch 19 Comments

Time series of O2 (blue) and VGADM (red). (Credit: Weijia Kuang, Science Advances, 2025)

In an Earth-sized take on the age-old ‘correlation or causality’ question, researchers have come across a fascinating match between Earth’s magnetic field and its oxygen levels since the Cambrian explosion, about 500 million years ago. The full results by [Weijia Kuang] et al. were published in Science Advances, where the authors speculate that this high correlation between the geomagnetic dipole and oxygen levels as recorded in the Earth’s geological mineral record may be indicative of the Earth’s geological processes affecting the evolution of lifeforms in its biosphere.

As with any such correlation, one has to entertain the notion that said correlation might be spurious or indirectly related before assuming a strong causal link. Here it is for example known already that the solar winds affect the Earth’s atmosphere and with it the geomagnetic field, as more intense solar winds increase the loss of oxygen into space, but this does not affect the strength of the geomagnetic field, just its shape. The question is thus whether there is a mechanism that would affect this field strength and consequently cause the loss of oxygen to the solar winds to spike.

Here the authors suggest that the Earth’s core dynamics – critical to the geomagnetic field – may play a major role, with conceivably the core-mantle interactions over the course of millions of years affecting it. As supercontinents like Pangea formed, broke up and partially reformed again, the impact of this material solidifying and melting could have been the underlying cause of these fluctuations in oxygen and magnetic field strength levels.

Although hard to say at this point in time, it may very well be that this correlation is causal, albeit as symptoms of activity of the Earth’s core and liquid mantle.

Replacing Crude Oil Fractional Distillation With Microporous Polyimine Membranes

June 21, 2025 by Maya Posch 12 Comments

Currently the typical way that crude oil is processed involves a fractional distillation column, in which heated crude oil is separated into the various hydrocarbon compounds using distinct boiling points. This requires the addition of significant thermal energy and is thus fairly energy intensive. A possible alternative has been proposed by [Tae Hoon Lee] et al. with a research article in Science. They adapted membranes used with reverse-osmosis filtration to instead filter crude oil into its constituents, which could enable skipping the heating step and thus save a lot of energy.

The main change that had to be made was to replace the typical polyamide films with polyimine ones, as the former have the tendency to swell up – and thus becomes less effective – when exposed to organic solvents, which includes hydrocarbons. During testing, including with a mixture of naphtha, kerosene and diesel, the polyimine membrane was able to separate these by their molecular size.

It should be noted of course that this is still just small scale lab-testing and the real proof will be in whether it can scale up to the flow rates and endurance required from a replacement for a distillation column. Since this research is funded in part by the fossil fuel industry, one can at least expect that some trial installations will be set up before long, with hopefully positive results.