Concrete Clears Its Own Snow

Humans are not creatures well suited to cold environments. Without a large amount of effort to provide clothing, homes, and food to areas with substantial winters, very few of us would survive. The same is true of a lot of our infrastructure since things like ice, frost heave, and large temperature swings can all negatively impact buildings, roadways, and other structures. A team at Drexel University in Pennsylvania has created a type of concrete they hope might solve some issues with the material in cold climates.

Specifically when it comes to sidewalks and roadways, traditional methods of snow and ice removal such as plowing and salting are generally damaging to the surface material, with salting additionally being damaging to vehicles. Freeze-thaw cycles aren’t kind to these surfaces either. This concrete, on the other hand, contains a low-temperature liquid paraffin which releases heat when it has a phase change, from a liquid to a solid. By incorporating the material into the concrete, it can warm itself as temperatures drop, maintaining a temperature above freezing to melt ice and snow. The warming effect isn’t indefinite, but lasts a significant amount of time during testing.

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Rock Salt May Lead The Way To Better Batteries

The regular refrain here when it comes to announcements of new battery chemistries hailed as potentially miraculous is that if we had a pound, dollar, or Euro for each one we’ve heard, by now we’d be millionaires. But still they keep coming, and it’s inevitable that there will one or two that break through the practicality barrier and really do deliver on their promise. Which brings us tot he story which has come our way today, the suggestion that something as simple as rock salt could triple the energy density of a lithium-ion vehicle battery.

The research led from Lawrence Berkeley National Laboratory started around the use of cobalt in the battery cathode, an expensive and finite resource with the added concern of being in large part a conflict mineral from the Democratic Republic of Congo. Cobalt is used in  the cathodes because its oxide crystals form a stable layered structure into which the lithium ions can percolate. Alternative layered-structure metal oxides perform less well in retaining the lithium ions, making them unsuccessful substitutes. It seems that the three-dimensional structure of a rock salt crystal performs up to three times better than any layered oxide, which is where the excitement comes from.

Of course, if it were that simple we’d all be using three-times-more-powerful, half-price 18650s right now, which of course we aren’t. The challenge comes in making a rock salt cathode which both holds the lithium ions, and keeps that property reliably over the thousands of charge cycles needed for a real-world application. This one may yet be anther dollar on that metaphorical pile, but it just might give us the batteries we’ve been looking for.

Then again, when you’re looking at exciting battery chemistry, why limit yourself to lithium?

Hackaday Prize 2023: Sleek Macro Pad Makes 2FA A Little Easier

We all know the drill when it comes to online security — something you know, and something you have. But when the “something you have” is a two-factor token in a keyfob at the bottom of a backpack, or an app on your phone that’s buried several swipes and taps deep, inconvenience can stand in the way of adding that second level of security. Thankfully, this “2FA Sidecar” is the perfect way to lower the barrier to using two-factor authentication.

That’s especially true for a heavy 2FA user like [Matt Perkins], who typically needs to log in and out of multiple 2FA-protected networks during his workday. His Sidecar is similar in design to many of the macro pads we’ve seen, with a row of Cherry MX key switches, a tiny TFT display — part of an ESP32-S3 Reverse TFT Feather — and a USB HID interface. Pressing one of the five keys on the pad generates a new time-based one-time password (TOTP) and sends it over USB as typed keyboard characters; the TOTP is also displayed on the TFT if you prefer to type it in yourself.

As for security, [Matt] took pains to keep things as tight as possible. The ESP32 only connects to network services to keep the time synced up for proper TOTP generation, and to serve up a simple web configuration page so that you can type in the TOTP salts and service name to associate with each key. He also discusses the possibility of protecting the ESP32’s flash memory by burning the e-fuses, as well as the pros and cons of that maneuver. The video below shows the finished project in action.

This is definitely a “use at your own risk” proposition, but we tend to think that in the right physical environment, anything that makes 2FA more convenient is probably a security win. If you need to brush up on the risks and benefits of 2FA, you should probably start here.

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How To Grow Your Own Pyramid Salt Crystals

The regular granular table salt you’re used to isn’t the most attractive-looking seasoning out there, even given its fundamentally compelling flavor. You don’t have to settle for boring old salt anymore though, because [Chase] has shown us you can grow your own pyramid salt crystals at home!

Pyramid salt crystals can grow naturally, and typically occur in locations where salt pools are undisturbed under the warmth of the sun. However, it’s possible to grow them on purpose, too. As a bonus, their hollow structure means they dissolve very quickly on the tongue, and can taste “saltier” than typical granular salt.

To grow your own, you’ll need a bag of salt, which is mixed with some water. You’ll want to do so in a glass dish, as the salty solution you’ll be making can ruin metal cookware. The dish can then be heated up on an electric hotplate, which is used to heat the solution to between 60 and 70°C.

A small amount of food-grade potassium alum is also added to the solution to calm the convection currents in the heated solution, allowing the crystals to form gently without sticking and clumping together. As the water boils away, the rectangular-pyramidal crystals grow.

Naturally, you must be careful before eating the results of any home-grown lab experiments. However, [Chase] reports having licked some of the crystals and has confirmed they do indeed taste salty. [Chase] also notes several ways in which the parameters can be changed to grow different types of pyramid crystals, too.

We’ve featured [Chase]’s crystal-growing work before. If you’ve got your own cool DIY crystal projects cooking up in the lab, be sure to let us know!

Electric Chopsticks Bring The Salt, Not The Pain

The Japanese people love their salt, perhaps as much as Americans love their sugar high fructose corn syrup and caffeine. But none of these are particularly good for you. Although humans do need some salt in their diets to continue existing, the average Japanese person may be eating too much of it on a regular basis — twice the amount recommended by the World Health Organization, according to Reuters. Cue the invention of electric chopsticks, which provide salty flavor without the actual sodium.

No, you won’t get shocked — not even a fresh 9 V to the tongue’s worth. The tips of the chopsticks are made of something food-safe and conductive, and one is wired to a bracelet that contains a small computer. Using a weak current, the chopsticks transmit sodium ions from the food to the tongue, which increases the perceived saltiness by 1.5x. The device was co-created by a Meiji University professor and a Japanese beverage maker, who hope to commercialize it sometime next year.

This isn’t the first time humans have used trickery when it comes to diets. The older among you may remember the miracle berry weight loss craze of the 1970s. When ingested first, miracle berries make sour things taste sweet, so chowing down on grapefruits and lemons suddenly sounds like a good idea. What people failed to realize was that the acidity would still wreak havoc on their teeth and tongues, leaving them regretful the next day.

Images via Reuters

3D Printed Climbing Holds, Now With Texture

Technology enables all kinds of possibilities to mold our environments in the way we best see fit. Plenty of ski resorts use snowmaking to extend their seasons, there are wave pools for surfing hundreds of miles away from oceans, and if you don’t live near any mountains you can build your own climbing wall as well. For the latter, many have turned to 3D printers to create more rock-like climbing grips but plastic doesn’t tend to behave the same as rock unless you do what [Giles Barton-Owen] did and incorporate salt into the prints.

For small manufacturers, typically the way that the rock texture is mimicked is by somehow incorporating sand, permanently, into the grip itself. This works well enough but is often too rough on climbers’ hands or otherwise doesn’t faithfully replicate a rock climbing experience. For these grips, instead of including sand, salt crystals of a particular size were added to a resin that was formed over the 3D printed grip. Once the resin cures substantially, the water-soluble salt can be washed away leaving a perfect texture to grab onto with chalked hands.

While this might not be a scalable method for large-scale climbing grip manufacturers, [Giles] hopes this method will help smaller operations or even DIY climbers to build more realistic grips without having to break the bank. In fact, he has already found some success at his local climbing gym using these grips. The method may be more difficult to scale for larger manufacturers but for anyone who wants to try it out themselves, all that’s needed for this build is a 3D printer, salt, and time.

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The (Sodium Chloride) Crystal Method

[Chase’s] post titled “How to Grow Sodium Chloride Crystals at Home” might as well be called “Everything You Always Wanted to Know about Salt Crystals (but Were Afraid to Ask).” We aren’t sure what the purpose of having transparent NaCl crystals are, but we have to admit, they look awfully cool.

Sodium chloride, of course, is just ordinary table salt. If the post were simply about growing random ugly crystals, we’d probably have passed over it. But these crystals — some of them pretty large — look like artisan pieces of glasswork. [Chase] reports that growing crystals looks easy, but growing attractive crystals can be hard because of temperature, dust, and other factors.

You probably have most of what you need. Table salt that doesn’t include iodine, a post, a spoon, a funnel, filter paper, and some containers. You’ll probably want tweezers, too. The cooling rate seems to be very important. There are pictures of what perfect seed crystals look like and what happens when the crystals form too fast. Quite a difference! Once you find a perfectly square and transparent seed crystal, you can use it to make bigger ones.

After the initial instructions, there is roughly half the post devoted to topics like the effect growth rate has on the crystal along with many pictures. There are also notes on how to form the crystals into interesting shapes like stars and pyramids. You can also see what happens if you use iodized salt.

If salt is too tame for you, try tin. Or opt for copper, if you prefer that.