Tech Universe: Tuesday 22 July

By Miraz Jordan

The Safelet. Photo / Safelet.com
The Safelet. Photo / Safelet.com

WRIST EASY: Just press the Safelet band on your wrist and you can summon help from friends, family and even the police, if you like. The safety bracelet works via a Bluetooth Low Energy connection to a smartphone. When you activate the signal the people you've selected to be your guardians receive an alert and are notified with your location. The bracelet is designed to help the wearer feel more confident when going out and about on their own, knowing that if something happens they don't need to be alone. There could be quite a few parents who might be happy for their kids to wear a device like that.

STICK WITH A BUDDY: If you've ever been frustrated by a weak cellphone signal then you could be interested in the goTenna. It's a peer-to-peer device that communicates slowly but over long distances with other goTennas, and without needing a cell signal, WiFi or a satellite.

The small baton, a little longer than a hand, pairs via Bluetooth with a smartphone. It uses ultra-low-band frequencies, 151-154 MHz, so it has low bandwidth but a very long range, limited only by the horizon. In open country at the top of a mountain the signal could travel up to 80 Km, but in a city it may only reach 1.5 Km. The idea is that you buy the device in pairs, at least, with one for yourself and one for each family member or buddy, then use it to send text messages or GPS coordinates.

LOOKS GOOD ON PAPER: Tossing another sheet of waste paper in the recycling bin? Just hold on a moment — that page could perhaps be turned into a supercapacitor to store an electric charge. Batteries use chemical reactions to store large amounts of energy, but are slow to charge. Capacitors, on the other hand, use an electric field and charge and release energy quickly. But they can't store much. Supercapacitors offer both speed and capacity, generally using forms of porous carbon that can suck up charge like a sponge. An Indian scientist found that waste paper, heated and cooled, then mixed with sulphuric acid at 180C and carbonised at 800C produced a form of carbon with a massive surface area of more than 2300 square metres per gram. Combined with an electrolyte gel the material forms a supercapacitor able to store a charge. The material could eventually be used in electric cars. And waste paper is abundant and inexpensive.

ROUGH AND READY: Try using a tablet out in the sun and the glare will probably lead you to quickly turn it off. A novel glass surface though reduces both glare and reflection. US researchers did two things to a piece of glass that reduced glare and made it anti-reflective. On a very fine scale, they roughened a glass surface so it could scatter light and ward off glare without reducing transparency. Then they etched nanoscale teeth into the surface to make it anti-reflective. A nice side effect was that the textured surface repelled water, mimicking a lotus leaf. A tablet with teeth.

SHAKY DESIGN: At the University of Nevada are three 50-ton shake tables that simulate earthquakes. The lab can be used to test the design of structures such as bridges so they have a better chance of withstanding an earthquake. One recent test was on a new design of bridge support. A reproduction of a portion of the bridge was built in the lab and strapped to the tables then loaded with sensors. The structure was put through ten different earthquakes, including one similar to the immensely destructive magnitude 6.9 Kobe quake of 1995. While damaged, the bridge design did remain standing, but the data from the shakes can now contribute to making it even safer. Shake, rattle and roll.

Miraz Jordan, knowit.co.nz

- NZ Herald

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