Humans have lots of basic requirements that need to be met in order to stay alive. Food is a necessary one, though it’s possible to go without for great stretches of time. Water is more important, with survival becoming difficult beyond a few days in its absence. Most of all, though, we crave oxygen. Without an air supply, death arrives in mere minutes.
The importance of oxygen is why airway management is such a key part of emergency medicine. It can be particularly challenging in cases where there is significant trauma to the head, neck, or surrounding areas. In these cases, new research suggests there may be an alternative route to oxygenating the body—through the rear.
By far, the most widely used psychoactive substance in the world is caffeine. It’s farmed around the world in virtually every place that it has cropped up, most commonly on coffee plants, tea plants, and cocoa plants. But is also found in other less common plants like the yaupon holly in the southeastern United States and yerba maté holly in South America. For how common it is and how long humans have been consuming it, it’s always been a bit difficult to quantify exactly how much is in any given beverage, but [Johnowhitaker] has a solution to that.
This build uses a practice called thin layer chromatography, which separates the components of a mixture by allowing them to travel at different rates across a thin adsorbent layer using a solvent. Different components will move to different places allowing them to be individually measured. In this case, the solvent is ethyl acetate and when the samples of various beverages are exposed to it on a thin strip, the caffeine will move to a predictable location and will show up as a dark smudge under UV light. The smudge’s dimensions can then be accurately measured to indicate the caffeine quantity, and compared against known reference samples.
Although this build does require a few specialized compounds and equipment, it’s by far a simpler and less expensive way of figuring out how much caffeine is in a product than other methods like high-performance liquid chromatography or gas chromatography, both of which can require extremely expensive setups. Plus [Johnowhitaker]’s results all match the pure samples as well as the amounts reported in various beverages so he’s pretty confident in his experimental results on beverages which haven’t provided that information directly.
A friend of mine and I both have a similar project in mind, the manufacture of custom footwear with our hackerspace’s shiny new multi-material 3D printer. It seems like a match made in heaven, a machine that can seamlessly integrate components made with widely differing materials into a complex three-dimensional structure. As is so often the case though, there are limits to what can be done with the tool in hand, and here I’ve met one of them.
I can’t get a good range of footwear for my significantly oversized feet, and I want a set of extra grippy soles for a particular sporting application. For that the best material is a rubber, yet the types of rubber that are best for the job can unfortunately not be 3D printed. In understanding why that is the case I’ve followed a fascinating path which has taught me stuff about 3D printing that I certainly didn’t know.
Newton strikes back, and I can’t force rubber through this thing.
A friend of mine from way back is a petrochemist, so I asked him about the melting points of various rubbers to see if I could find an appropriate filament His answer, predictably, was that it’s not that simple, because rubbers don’t behave in the same way as the polymers I am used to. With a conventional 3D printer filament, as the polymer is fed into the extruder and heated up, it turns to liquid and flows out of the nozzle to the print. It ‘s then hot enough to fuse with the layer below as it solidifies, which is how our 3D prints retain their shape. This property is where we get the term “plastic” from, which loosely means “Able to be moulded”.
My problem is that rubber doesn’t behave that way. As any casual glance at a motor vehicle will tell you, rubber can be moulded, but it doesn’t neatly liquefy and flow in the way my PLA or PET does. It’s a non-Newtonian fluid, a term which I was familiar with from such things as non-drip paint, tomato ketchup, or oobleck, but had never as an electronic engineer directly encountered in something I am working on. Continue reading “Why Can’t I 3D Print With Rubber?”→
Although flying well under the radar of the average Linux user, D-Bus has been an integral part of Linux distributions for nearly two decades and counting. Rather than using faster point-to-point interprocess communication via a Unix socket or such, an IPC bus allows for IP communication in a bus-like manner for convenience reasons. D-Bus replaced a few existing IPC buses in the Gnome and KDE desktop environments and became since that time the de-facto standard. Which isn’t to say that D-Bus is well-designed or devoid of flaws, hence attracting the ire of people like [Vaxry] who recently wrote an article on why D-Bus should die and proposes using hyprwire instead.
The broader context is provided by [Brodie Robertson], whose video adds interesting details, such as that Arch Linux wrote its own D-Bus implementation rather than use the reference one. Then there’s CVE-2018-19358 pertaining to the security risk of using an unlocked keyring on D-Bus, as any application on said bus can read the contents. The response by the Gnome developers responsible for D-Bus was very Wayland-like in that they dismissed the CVE as ‘works as designed’.
One reason why the proposed hyperwire/hyprtavern IPC bus would be better is on account of having actual security permissions, real validation of messages and purportedly also solid documentation. Even after nearly twenty years the documentation for D-Bus consists mostly out of poorly documented code, lots of TODOs in ‘documentation’ files along with unfinished drafts. Although [Vaxry] isn’t expecting this hyprwire alternative to be picked up any time soon, it’s hoped that it’ll at least make some kind of improvement possible, rather than Linux limping on with D-Bus for another few decades.
Having an enclosed 3D printer can make a huge difference when printing certain filaments that are prone to warping. It’s easy enough to build an enclosure to stick your own printer in, but it can get tricky when you want to actively control the conditions inside the chamber. That’s where [Jayant Bhatia]’s Chamber Master project comes in.
This system is built around the ESP32 microcontroller, which provides control to various elements as well as hosts a web dashboard letting you monitor the chamber status remotely. The ESP32 is connected to an SSD1306 OLED display and a rotary encoder, allowing for navigating menus and functions right at the printer, letting you select filament type presets and set custom ones of your own. A DHT11 humidity sensor and a pair of DS18B20 temperature sensors are used to sense the chamber’s environment and intake temperatures.
One of the eye-catching features of the Chamber Master is the iris-controlled 120 mm fan mounted to the side of the chamber, allowing for an adjustable-size opening for air to flow. When paired with PWM fan control, the amount of airflow can be precisely controlled.
Although Nissan has been in the doldrums ever since getting purchased by Renault in the early 2000s, it once had a reputation as a car company that was always on the cutting edge of technology. Nissan was generally well ahead of its peers when bringing technologies like variable valve timing, turbocharging, fuel injection, and adjustable suspension to affordable, reliable vehicles meant for everyday use. Of course, a lot of this was done before computers were as powerful as they are today so [Ronald] set out to modernize some of these features on his 1978 Datsun 280Z.
Of course there are outright engine swaps that could bring a car like this up to semi-modern standards of power and efficiency, but he wanted to keep everything fully reversible in case he wants to revert to stock in the future, and didn’t want to do anything to the engine’s interior. The first thing was to remove the complicated mechanical system to control the throttle and replace it with an electronic throttle body with fly-by-wire system and a more powerful computer. The next step was removing the distributor-based ignition system in favor of individual coil packs and electronic ignition control, also managed by the new computer. This was perhaps the most complicated part of the build as it involved using a custom-made hall effect sensor on the original distributor shaft to tell the computer where the engine was in its rotation.
The final part of this engine modernization effort was upgrading the fuel delivery system. The original fuel injection system fired all of the injectors all the time, needlessly wasting fuel, but the new system only fires a specific cylinder when it needs fuel. This ended up improving gas mileage dramatically, and dyno tests also showed these modifications improved power significantly as well. Nissan hasn’t been completely whiffing since the Renault takeover, either. Their electric Leaf was the first mass-produced EV and is hugely popular in all kinds of projects like this build which uses a Leaf powertrain in a Nissan Frontier.
The worst thing about the getting people together is when everyone starts fighting over their favourite map projection– maybe you like the Watterman Butterfly, but your cousin really digs Gall-Peters, and that one Uncle who insists on defending Mercator after a couple of beers. Over on Instructables [madkins9] has an answer to that problem that will still let you play a rousing game of Risk– which will surely not drag on into the night and cause further drama– skip the projection, and put the game on a globe.
The pieces are from a 1960s version. The abstract tokens have a certain charm the modern ones lack.
Most globes, being cardboard, aren’t amenable to having game pieces cling to them. [madkins9] thus fabricates a steel globe from a pair of pre-purchased hemispheres. Magnets firmly affixed to the bases of all game pieces allow them to stick firmly to the spherical play surface. In a “learn from my mistakes” moment, [madkins] suggests that if you use two pre-made hemispheres, as he did, you make sure they balance before welding and painting them.
While those of us with less artistic flair might be tempted to try something like a giant eggbot, [madkins] was able to transfer the Risk world map onto his globe by hand. Many coats of urethane mean it should be well protected from the clicking or sliding magnet pieces, no matter how long the game lasts. In another teachable moment, he suggests not using that sealer over sharpie. Good to know.
Once gameplay is finished, the wooden globe stand doubles as a handsome base to hold all the cards and pieces until the next time you want to end friendships over imaginary world domination. Perhaps try a friendly game of Settlers of Catan instead.
