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Electronics Technology

Lithium battery fires could be prevented using graphene coating, study says

Researchers from the University of Illinois at Chicago College of Engineering have published a paper in journal Advanced Functional Materials wherein they have suggested that a thin coating of graphene could help protect fires in lithium batteries.

Over the last few years there has been a surge in the use of lithium batteries – primarily due to their size and energy density – in the electric vehicle segment. Lithium batteries hold the promise of allowing electric vehicles to travel several hundred miles on one charge. However, there is one problem that affects their increased use – occasional fire – an occurrence known to battery researchers as “thermal runaway.” These fires occur most frequently when the batteries overheat or cycle rapidly. With more and more electric vehicles on the road each year, battery technology needs to adapt to reduce the likelihood of these dangerous and catastrophic fires.

Researchers report that graphene may take the oxygen out of lithium battery fires. If the oxygen combines with other flammable products given off through decomposition of the electrolyte under high enough heat, spontaneous combustion can occur.

Scientists knew that graphene sheets are impermeable to oxygen atoms. Graphene is also strong, flexible and can be made to be electrically conductive. Scientists thought that if they wrapped very small particles of the lithium cobalt oxide cathode of a lithium battery in graphene, it might prevent oxygen from escaping. First, the researchers chemically altered the graphene to make it electrically conductive. Next, they wrapped the tiny particles of lithium cobalt oxide cathode electrode in the conductive graphene.

When they looked at the graphene-wrapped lithium cobalt oxide particles using electron microscopy, they saw that the release of oxygen under high heat was reduced significantly compared with unwrapped particles.

Next, they bound together the wrapped particles with a binding material to form a usable cathode, and incorporated it into a lithium metal battery. When they measured released oxygen during battery cycling, they saw almost no oxygen escaping from cathodes even at very high voltages. The lithium metal battery continued to perform well even after 200 cycles.

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Science

Industrial 3D printing could soon be used for outdoor sporting goods

Gigabot X, an open source industrial FPF 3D printer, developed by engineers from Michigan Technological University and re:3D, Inc. could soon be used to manufacture outdoor sporting goods such as kayak paddles, snowshoes, and skateboards.

The newly developed 3D printer can use waste plastic particles and reform it into large, strong prints. Because of the unique challenges presented by sporting goods — size, durability, specificity — the team chose several Upper Peninsula-inspired items. The findings of the study have been published in Additive Manufacturing.

In the paper the team lays out how fab labs, which are prototyping and technical workshops that allow personal digital fabrication, and other 3D printing hubs like makerspaces, public libraries or schools can economically sustain themselves while printing environmentally friendly products using FPF. In some cases, the return on investment for a Gigabot X reached above 1,000 percent for high-capacity use paired with recyclable feedstock.

That’s a hallmark of the Gigabot X — last year a Michigan Tech and re:3D collaborative study showed that it could be used with a wide range of plastics plucked from the waste stream to live on in a new productive life. The system is based on a previous design from the MOST Lab, the recyclebot, which makes waste plastic filament for 3D printers. Pearce’s team has looked deep into better ways to sort, sift and classify plastic to improve its 3D printability. Melting and extruding, however, does weaken plastic, it can withstand five cycles before it’s mechanically compromised. What’s new with the Gigabot X is the process called fused particle fabrication (FPF) or fused granular fabrication (FGF) that skips the step of making filament before 3-D printing and saves on one melt cycle. Basically, it prints directly from shredded waste. The Gigabot X’s size and versatility to use any material including waste is reflected in the machine’s economics.

While not cheap by household standards — the Gigabot X runs around $18,500 — the upfront investment has greater potential return. The team used three case studies: a skateboard deck, double-bladed kayak paddle — both child-sized and adult-sized fitted on an aluminum pipe — and snowshoes.

Using their sporting goods prints, Pearce and his team compared costs of low-end and high-end options for commercially available products, prints with commercial filament, prints with commercial pellets and prints with recycled plastic. They ran these against four capacity scenarios: continuous printing, one new start per day, two new starts per day and printing once per week. The printed kayak paddle, which was the trickiest to produce and compare because of the metal pipe, was financially comparable to the least expensive off-the-shelf paddle. Skateboards and snowshoes were both easy to produce and significantly lower in cost than commercial products. FPF printing beat the economics of even the cheapest decks using commercial pellets and dropped in cost using waste plastic. Over their lifetime, if operated even only once a day, the Gigabot X could produce millions of dollars of sporting goods products.

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Lifestyle

Beauty spot in genes said to determine beauty of a person’s face

Scientists have determine ‘beauty spots’ in human genome that they claim are linked to facial beauty. They study has been carried out by Qiongshi Lu and colleagues at the University of Wisconsin-Madison and findings have been published in PLOS Genetics.

For centuries humans have been known to devote a lot of time to look beautiful with a chunk of that time being devoted to facial beauty. While a person’s attractiveness is associated with academic performance, career success and economic mobility, having a beautiful face is still important for humans. Scientists haven’t been able to find out how a person derives their facial beauty and if there are genetic links.

In their latest study researchers performed a genome-wide association study using genetic information from 4,383 individuals to pinpoint parts of the genome linked to facial beauty. They had volunteers score yearbook photos based on attractiveness from participants with European ancestry and compared the scores to each person’s genetic information. The researchers identified several genes related to facial attractiveness, but their roles and relatedness to other human traits varied by sex. In women, certain genetic variations linked to beauty also appeared to be related to genes impacting body mass, while in males, variants were linked to genes affecting blood cholesterol levels.

The study provides new insights into the genetic factors underlying facial attractiveness and highlights the complex relationships between beauty and other human traits. “Similar to many other human traits, there is not a ‘master gene’ that determines a person’s attractiveness,” author Qiongshi Lu observed.

The researchers acknowledge, however, that their findings are based on a homogenous group of individuals of the same age and ethnic background. They propose that future analyses including a larger sample size of people from diverse populations and ages will further advance our understanding of this highly valued human trait.