20th Feb 2017
GS : 1 - GEOGRAPHY
Why Earth’s inner core doesn’t melt
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(The Hindu)
Scientists have discovered why the crystallised iron core of the Earth remains solid, despite being hotter than
the surface of the Sun.
Why earth’s core doesn’t melt?
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On the edge of the inner core, pieces of crystals’ structure continuously melt and diffuse only to be reinserted
due to high pressure like “shuffling deck of cards.”
•
This energy distribution cycle keeps the crystal stable and the core solid.
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Spinning within Earth’s molten core is a crystal ball — actually a mass formation of almost pure crystallised
iron — nearly the size of the moon.
Key facts:
•
As with all metals, the atomic-scale crystal structures of iron change depending on the temperature and
pressure the metal is exposed to.
•
Atoms are packed into variations of cubic, as well as hexagonal formations. At room temperatures and normal
atmospheric pressure, iron is in what is known as a body-centred cubic (BCC) phase, which is a crystal
architecture with eight corner points and a centre point.
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However at extremely high pressure, the crystalline structures transform into 12-point hexagonal forms, or a
close packed (HCP) phase.
•
At Earth’s core, where pressure is 3.5 million times higher than surface pressure — and temperatures are some
6,000 degrees higher — scientists have proposed that the atomic architecture of iron must be hexagonal.
•
Pure iron likely accounts for 96% of the inner core’s composition, along with nickel and possibly light elements.
GS : 3 - SCIENCE AND TECHNOLOGY
Scientists develop high-quality graphene from soybean
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(Indian Express)
In a breakthrough, scientists have used the humble soybean to make the world’s strongest material graphene
commercially more viable.
About Graphene:
•
Graphene is a carbon material that is one atom thick. Its thin composition and high conductivity means it is
used in applications ranging from miniaturised electronics to biomedical devices.
•
These properties also enable thinner wire connections; providing extensive benefits for computers, solar
panels, batteries, sensors and other devices. Until now, the high cost of graphene production has been the
major roadblock in its commercialisation.
•
The potential applications of graphene include water filtration and purification, renewable energy, sensors,
personalised healthcare and medicine, to name a few.
•
Graphene has excellent electronic, mechanical, thermal and optical properties as well. Its uses range from
improving battery performance in energy devices, to cheaper solar panels.
Development and significance:
•
Previously, graphene was grown in a highly-controlled environment with explosive compressed gases,
requiring long hours of operation at high temperatures and extensive vacuum processing. Scientists have
developed a novel “GraphAir” technology which eliminates the need for such a highly-controlled environment.
•
The technology grows graphene film in ambient air with a natural precursor, making its production faster and
simpler. This ambient-air process for graphene fabrication is fast, simple, safe, potentially scalable, and
integration friendly.
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The unique technology is expected to reduce the cost of grapheme.
•
GraphAir transforms soybean oil – a renewable, natural material – into graphene films in a single step.
•
GraphAir technology results in good and transformable graphene properties, comparable to graphene made
by conventional methods.
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GS : 1 - GEOGRAPHY
Barren Island volcano, India’s only live volcano, became active in January
•
India’s only live volcano which had started
showing activity in 1991 after lying dormant for
over 150 years has again started spewing ash.
Key facts:
•
The only live volcano in the Andaman and
Nicobar islands is erupting once again.
•
The Barren Island volcano, located 140-km
north-east of Port Blair, dormant for more than
150 years started erupting in 1991 and has
since then shown intermittent activity
•
A team of scientists led by Abhay Mudholkar,
from CSIR-National Institute of Oceanography
(CSIR-NIO) in Goa reported that the volcano is
active and spewing smoke and lava once again.
MISCELLANEOUS
INSV Tarini
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The Indian Navy’s second ocean going sailboat Indian Naval Sailing Vessel Tarini was recently inducted.
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It is stated to be the platform forFirst Indian All Women Circumnavigation of the Globe expedition of the
Indian Navy.
•
Indian Navy will is operating four sailing vessels capable of open ocean deployments, that is, Tarangini,
Sudarshini, Mhadei and Tarini, all four of which have been built in shipyards at Goa.
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