18 | New Scientist | 28 March 2020Solar systemJust opening a bottle
releases microplasticsTINY pieces of plastic pollution
are produced just by opening a
bottle or tearing a food wrapper.
Microplastics are between 0.
and 5 millimetres in size and are
usually either produced directly,
or form when large plastic debris
breaks up. We know that millions
of tonnes of microplastics get into
the environment and can harm
marine life. Microplastics are also
found in food, although the effectFishy solution to
making flex screensTHE scales of fish could provide an
eco-friendly alternative to plastic
for use in flexible displays for
electronic devices.
Flexibility is important for
wearable electronics that need
displays that bend, fold or twist
easily, says Hai-Dong Yu at Nanjing
Tech University in China. Plastic
has been the go-to material for
this, but sustainable, low-cost
alternatives are sought after.
Fish scales account for 3 per cent
of the 70.5 million metric tonnes
of fish processed globally each
year. The scales usually go to
waste, but Yu and his team saw
potential for flexible electronics.
They extracted gelatin from
scales and used this to create an
extremely thin film of material.
Tiny silver nanowires were
incorporated into it, to act as
electrodes, along with a light-
emitting material to provideBiomaterials^ PollutionBOMBING an asteroid has taught us
how old it is. In April, the Japanese
Hayabusa 2 spacecraft launched
a copper projectile at the asteroid
Ryugu, and now we have the first
data on the crater it left behind.
The main purpose of this was
to collect a pristine sample of the
material beneath the asteroid’s
surface. But Masahiko Arakawa
at Kobe University in Japan and
his team analysed images of
the collision to study the crater
formation process.
When the 2-kilogram projectile
smashed into Ryugu, it blasted
away sand and rocks and moved
a 5-metre-wide boulder. The
resulting crater was about 14.
metres wide and 2.3 metres deep.
We can use the number and size
of craters on asteroids to estimate
how old they are. Previous studiesof Ryugu (pictured) determined that
it was either about 9 million years
old or about 160 million years old,
depending on how much the size of
craters there has been limited by the
strength of the asteroid’s surface.
From observing the formation
of this new crater, the researchers
found that underneath its blanket of
boulders, Ryugu’s surface isn’t very
sturdy. It is more like sand than rock.
They say this confirms that Ryugu
is only about 9 million years old
(Science, doi.org/dp6q).
Asteroids like Ryugu form when
larger objects get smashed up and
the remnants reaccumulate into
“rubble piles”. There is usually
lots of debris left behind from such
a smash-up, and we may be able to
identify other objects in the asteroid
belt that are related to Ryugu in the
future. Leah CraneSpace rock Ryugu gives
up secrets of its age
on human health is still unclear.
Cheng Fang at the University
of Newcastle, Australia, and his
team tested whether everyday
activities could be part of the
problem. They opened common
plastic items such as bags, bottles
and packaging film by twisting the
bottle cap or tearing the bag, for
example, or by cutting them with
scissors or a knife.
The team used a scale that is
sensitive to weights as low as
1 nanogram to collect and measure
the microplastics that landed on
its surface. Between about 10 and
30 nanograms of microplastic
were released from opening the
plastic items – between 14,
and 75,000 individual particles.
But the team says that the true
amount released is probably
even higher, because many of
these particles are statically
charged and remain in the air.
Most of the fragments were
made of polythene, a widely used
plastic (Nature Scientific Reports,
doi.org/dp6z). Gege Lilight for the electronic display.
The result was a flexible
display that fully biodegraded
after 24 days in soil. A plastic
display can takes centuries to
break down. “We are excited
about boosting the development
of green, flexible electronics,
which may drive a paradigm
shift in our daily life,” says Yu.
He says that, in addition to
biodegradability, the fish-scale
films have the advantages of
high transparency, low surface
roughness and low cost. They
can also be easily recycled by
dissolving them in warm water
(ACS Nano, doi.org/dp6m).
Dipankar Mandal at the
Institute of Nano Science and
Technology in Mohali, India,
says we can expect to see more
“bio-electronics” like this in the
near future. Alongside fish scales,
other biological materials are
being explored for similar
purposes, including cellulose
from cotton fibres and silk protein
from silkworms. Layal LiverpoolJAX
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