“• Radioactivity is a phenomenon of spontaneous emission
of proton (a-particles), electrons (ß-particles) and
gamma rays (short wave electromagnetic waves) due to
disintegration of atomic nuclei of some elements. These
cause radioactive pollution.

Radiations are of two types with regard to the mode of
their action on cells.
1. Non-ionising radiations:
• They include short-wave radiations such as ultraviolet
rays, which forms a part of solar radiation.
• They have low penetrating power and affect the cells
and molecules which absorb them.
Hence, statement 1 is correct.
• They damage eyes which may be caused by reflections
from coastal sand, snow (snow blindness), directly looking
towards sun during eclipse.
Hence, statement 2 is correct.
• They injure the cells of skin and blood capillaries producing
blisters and reddening called sunburns.
2. Ionising radiations.
• They include X-rays, cosmic rays and atomic radiations
(radiations emitted by radioactive elements).
Hence, statement 3 is incorrect.
• Ionising radiations have high penetration power and
cause breakage of macro molecules.
• The molecular damage may produce short range
(immediate) or long range (delayed) effects.
i. Short range effects include burns, impaired metabolism,
dead tissues and death of the organisms.
ii. Long range effects are mutations increased incidence
of tumors and cancer, shortening of life-span and developmental
changes.
iii. The mutated gene can persist in living organisms and
may affect their progeny.
• The actively dividing cells such as Embryo, foetus, cells
of skin, intestinal lining, bone marrow and gamete
forming cells are more sensitive to radiations.
• Some species of animals and plants preferentially
accumulate specific radioactive materials. For example, oysters deposit 65Zn, fish accumulate 55Fe, marine animals selectively deposit 90Sr.”

“Why in News
Recently, a group of astrophysicists have found that
the closest known brown dwarf, Luhman 16A shows
signs of cloud bands similar to those seen on Jupiter and
Saturn.
They used the technique of polarimetry to determine
the properties of atmospheric clouds outside of the
solar system.

Polarimetry
• The concept of polarimetry technique was put forth
by Indian astrophysicist Sujan Sengupta, that the light
emitted by a cloudy brown dwarf, or reflected off
an extrasolar planet, will be polarised.
• Polarimetry is the study of polarization. Polarization
is a property of light that represents the direction
that the light wave oscillates.
Hence, statement 1 is correct.
• When light is reflected off of particles it can favor
a certain angle of polarization. By measuring the
preferred polarization of light from a distant system,
astronomers can deduce the presence of clouds.
(Hence, statement 2 is correct).
However, in case of Luhman 16A, the researchers
have found the actual structure of the clouds (not
only their presence).
• The polarimetry technique isn’t limited to brown
dwarfs. It can also be applied to exoplanets orbiting
distant stars, or even stars. However, light from brown
dwarfs is ideal for the study.”

–

“Why in News
The Centre has advised the Assam state government
to go for culling of pigs affected by the African Swine
Fever (ASF).

African Swine Fever
• It is a highly contagious and fatal animal disease that infects and leads to an acute form of hemorrhagic fever in domestic and wild pigs. The mortality is close to 100% and since the fever has no cure, the only way to stop its spread is by culling
the animals. Hence, statements 1 is incorrect while the 3rd statement is correct.
• It was first detected in Africa in the 1920s.
• ASF is not a threat to human beings since it only spreads from animals to other animals.
Hence, statement 2 is incorrect.
• ASF is a disease listed in the World Organisation for
Animal Health (OIE) Terrestrial Animal Health Code
and thus, reported to the OIE.”

“Why in News
Recently, a group of researchers (including a recipient
of the INSPIRE Faculty Award) have made significant
achievements in developing nanomaterials based supercapacitors to achieve high energy density and power
density of supercapacitors.

Nanomaterials Based Supercapacitors:
• The researchers have been working on carbon
(Carbon Nanotubes, Graphene) nanomaterials
based supercapacitors to achieve high energy
density and power density of supercapacitors.
• High energy density of supercapacitors suggests
that constant current can be withdrawn for a longer
duration without recharging. Hence automobiles
can run longer distances without charging.
• Thus, researchers have developed a reduced
graphene oxide (rGO) at a moderate temperature
of 100°C with high capacitance performance. It is
cost-effective and suitable for commercial purposes.
• The focus on energy devices paves the way for
the development of cost-effective and efficient
devices, which can be used for energy storage
application.”

“Why in News
Recently, China has successfully launched the Long
March 5B’ rocket and prototype spacecraft.

International Space Station (ISS)
• ISS is a habitable artificial satellite – the single
largest man-made structure in low earth orbit. Its
first component was launched into orbit in 1998.
• It circles the Earth in roughly 92 minutes and
completes 15.5 orbits per day.
• The ISS programme is a joint project between five
participating space agencies: NASA (United States),
Roscosmos (Russia), JAXA (Japan), ESA (Europe),
and CSA (Canada) but its ownership and use has
been established by intergovernmental treaties
and agreements.
• It serves as a microgravity and space environment
research laboratory in which crew members conduct
experiments in biology, human biology, physics,
astronomy, meteorology, and other fields.
• Continuous presence at ISS has resulted in the longest
continuous human presence in the low earth orbit.
• It is expected to operate until 2030”

“Why in News
The Oxford University has created a Stringency Index
which shows how strict a country’s measures were and
at what stage of the Covid-19 spread, it enforced these.

Stringency Index
• The Government Response Stringency Index is a
composite measure based on various response
indicators including school and workplace closures,
stay-at-home policies and travel bans, rescaled to a
value from 0 to 100.
• A higher index score indicates a higher level of
stringency (100 = strictest response).
• It is among the metrics used by the Oxford Coronavirus
Government Response Tracker (OxCGRT).
• The Tracker has a team of 100 Oxford community
members who update a database of 17 indicators of
government response.”