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Coin cells are useful things that allow us to run small electronic devices off a tiny power source. However, they don’t have a lot of capacity, and they can run out pretty quickly if you’re hitting them hard when developing a project. Thankfully, [bobricius] has just the tool to help.

The device is simple – it’s a PCB sized just so to fit into a slot for a CR2016 or CR2032 coin cell. The standard board fits a CR2016 slot thanks to the thickness of the PCB, and a shim PCB can be used to allow the device to be used in a CR2032-sized slot instead.

It’s powered via a Micro USB connector, and has a small regulator on board to step down the 5 V supply to the requisite 3 V expected from a typical coin cell. [bobricius] also gave the device a neat additional feature – a pair of pads for easy attachment of multimeter current probes. Simply open the jumper on the board, hook up a pair of leads, and it’s easy to measure the current being drawn from the ersatz coin cell.

Building a better supercomputer is something many tech companies, research outfits, and government agencies have been trying to do over the decades. There’s one physical constraint they’ve been unable to avoid, though: conducting electricity for supercomputing is expensive.

Not in an economic sense—although, yes, in an economic sense, too—but in terms of energy. The more electricity you conduct, the more resistance you create (electricians and physics majors, forgive me), which means more wasted energy in the form of heat and vibration. And you can’t let things get too hot, so you have to expend more energy to cool down your circuits.

New applications in energy, defense and telecommunications could receive a boost after a team from The University of Texas at Austin created a new type of “nanocrystal gel”—a gel composed of tiny nanocrystals each 10,000 times smaller than the width of a human hair that are linked together into an organized network.

The crux of the team’s discovery is that this is easily tunable. That is, it can be switched between two different states by changing the temperature. This means the material can work as an , absorbing different frequencies of light depending on whether it’s in a gelled state or not. So, it could be used, for example, on the outside of buildings to control heating or cooling dynamically. This type of optical filter also has applications for defense, particularly for thermal camouflage.

The gels can be customized for these wide-ranging applications because both the nanocrystals and the molecular linkers that connect them into networks are designer components. Nanocrystals can be chemically tuned to be useful for routing communications through fiber optic networks or keep the temperature of space craft steady on remote planetary bodies. Linkers can be designed to cause gels to switch based on ambient temperature or detection of environmental toxins.