Graphene-based supercapacitor a step closer to commerical reality

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Monash University researchers have created a compact electrode that uses a liquid electrolyte to maintain space between graphene sheets (Image: Shutterstock)

Graphene-based supercapacitors have already proven the equal of conventional supercapacitors – in the lab. But now researchers at Melbourne’s Monash University claim to have developed of a new scalable and cost-effective technique to engineer graphene-based supercapacitors that brings them a step closer to commercial development.
With their almost indefinite lifespan and ability to recharge in seconds, supercapacitors have tremendous energy-storage potential for everything from portable electronics, to electric vehicles and even large-scale renewable energy plants. But the drawback of existing supercapacitors has been their low energy density of around 5 to 8 Wh/liter, which means they either have to be exceedingly large or recharged frequently.
Professor Dan Li and his team at Monash University’s Department of Materials Engineering has created a graphene-based supercapacitor with an energy density of 60 Wh/liter, which is around 12 times higher than that of commercially available supercapacitors and in the same league as lead-acid batteries. The device also lasts as long as a conventional battery.
To maximize the energy density, the team created a compact electrode from an adaptive graphene gel film they had previously developed. To control the spacing between graphene sheets on the sub-nanometer scale, the team used liquid electrolytes, which are generally used as the conductor in conventional supercapacitors.
Unlike conventional supercapacitors that are generally made of highly porous carbon with unnecessarily large pores and rely on a liquid electrolyte to transport the electrical charge, the liquid electrolyte in Li’s team’s supercapacitor plays a dual role of conducting electricity and also maintaining the minute space between the graphene sheets. This maximizes the density without compromising the supercapcitor’s porosity, they claim.

Twitter finally gets tougher on death and rape threats

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It's been an exceedingly ugly fortnight on Twitter. Following a successful campaign orchestrated by journalist and feminist Caroline Criado-Perez to have a woman reinstated on Bank of England banknotes, she has been subjected to a relentless campaign of harassment, with rape and death threats being received by Criado-Perez at a rate of nearly one per minute on July 24, the day it was confirmed that her campaign had been a success. After being the platform for sustained threats and abuse for almost two weeks, Twitter has finally begun to act.
London MP Stella Creasy and television presenter and historian Mary Beard are among those who, like Criado-Perez, have received misogynistic death and rape threats through the social messaging service. Creasy's apparent crime against mankind was to post updates to Twitter in support of Criado-Perez. Beard (a long-time victim of online abuse) was to join in with a one-day boycott of the service on Sunday (proposed by columnist Caitlin Moran, who has also been on the end of threats and abuse), but broke silence to report yet more threats.
By July 30, two men in their 20s had been arrested in connection with harassment and malicious communication, but these arrests are only the tip of the iceberg. Hadley Freeman, India Knight, Grace Dent, Laura Penny and Catherine Mayer have also received threats via Twitter in recent days.
Twitter itself was slow to respond. After Criado-Perez contacted Twitter's Manager of Journalism and News, his remarkable response was to temporarily lock his own account so that his updates would only be seen by people already following him (and new followers would need his permission to see them). It took Twitter's UK General Manager Tony Wang a further week to apologize on Twitter, but in a post to Twitter's UK blog that same day (Saturday), Wang and Senior Director of Trust and Safety, Del Harvey, listed a number of measures intended to address the problem.
Perhaps most notable is that Twitter has introduced a "report tweet" button in the latest version of the official iOS app and on the mobile version of the website. The button should appear in the official Android app and on the main website during September. This would appear to be a direct response to an online petition with over 120,000 signatories which called for exactly this.

2013 Nexus 7 vs. iPad mini

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If you're shopping for a smallish tablet, we wouldn't blame you for narrowing it down to the iPad mini and Google's new Nexus 7. But how do you choose between the two? Let Gizmag lend a hand, as we compare the specs (and other features) of the two mini-tablets.

Size

The two tablets are roughly the same height, but are proportioned differently. The new Nexus 7 is 16 percent narrower than the iPad mini. The Google/Asus tablet is also a bit thicker, by 21 percent.

Weight

That narrower build helps the 2nd-gen Nexus 7 to tip the scales at 6 percent lighter than the iPad mini.
If you look at weight relative to surface area, though, the iPad mini actually comes in at about eight percent lighter. So it's possible the iPad mini will, in a sense, feel lighter in hand.

Build

Like the original Nexus 7, the new model sports a plastic construction. The updated tablet does skip out on the rubbery backing of the 2012 model though: this one has a smooth matte finish.
The iPad mini is made of Apple's favorite, anodized aluminum.

MagPen offers a new take on the stylus

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The MagPen contains a magnet which is detected by the phone's existing

The humble smartphone stylus may soon be gaining new features, thanks to a seemingly simple piece of technology. Developed by Korea Advanced Institute of Science and Technology (KAIST) PhD student Sungjae Hwang, the MagPen is essentially just a plastic tube covered in conductive tape, with conductive rubber tips at either end and a coin-shaped magnet inserted half-way down its length. Via a custom app, however, magnetometers already present in the phone are able to determine where that magnet is in relation to the screen, and respond with a variety of drawing and writing functions.
Any existing smartphone or tablet should be compatible, as long as it already contains the magnetometers and associated electronics that most such devices use as a compass.
By sensing the proximity of the pen's magnet, the magnetometer-enabled app is able to tell not only how close the pen is to the screen, but also where its tip is on the screen, the angle at which it’s being held, and even the amount of finger pressure that’s being exerted on the glass. Different “ink” colors can even be chosen by going off the screen, and dragging the pen’s tip across the phone’s frame.

Because the app can differentiate between the magnetic qualities of multiple MagPens, users could alternately change colors by using different pens.
The app can also tell when the magnet (and thus the pen) has been spun around, by detecting which pole is closest to the phone. This allows for extra functionality, letting one end of the pen be used for writing and the other for erasing, as an example. In another mode, turning the pen around allows users to change between different line widths – this can also be done simply by pressing harder when drawing. In fact, the pen can be spun in three different fashions, each of which allows the user to access different functions.

Google floats balloon-powered internet network with Project Loon

Google recently launched Project Loon, which will send internet-enabled balloons into the stratosphere to provide high-speed connectivity in remote areas

Almost two-thirds of the world does not have access to high-speed internet, but Google is determined to change that. Unfortunately, setting up an affordable infrastructure in remote areas is beyond even a huge multinational corporation's capabilities, which is why the company had to devise a completely out-of-the-box solution called Project Loon. As part of the project, Google recently launched a series of internet-enabled balloons into the stratosphere over New Zealand to provide broadband connectivity to rural areas.