Current Affairs - Science & Technology

Explanation :

Context: Recently, Stardust 1.0 has been launched from USA, which became the first commercial space launch powered by biofuel.

Explanation:

Biofuels

• Any hydrocarbon fuel that is produced from an organic matter (living or once living material) in a short period of time is considered a biofuel.
• Biofuels may be solid, liquid or gaseous in nature.

First Generation Biofuels

• Fuels produced from sugar, starch, vegetable oil, or animal fats utilizing conventional technology.
• Examples: Bioalcohols, Biodiesel, Vegetable Oil, Bioethers, Biogas.

Second Generation Biofuels

• Fuels made from non-food crops such as cellulosic biofuels and waste biomass i.e. stalks of wheat and corn, and wood).
• Example: cellulose ethanol

Third Generation Biofuels

• Fuels made from micro-organisms such as algae.
• It doesn’t require cultivable/arable land for production.
• Example: Butanol

Fourth Generation Biofuels

• In the production of these fuels, crops that are genetically engineered to take in high amounts of carbon are grown and harvested as biomass.
• The crops are then converted into fuel using second generation techniques.
• Like the third generation, fourth-generation biofuels are made using non-arable land. However, unlike the third, they do not need the destruction of biomass.
• Examples: electrofuels and photo-biological solar fuels

Explanation :

• China has completed its BeiDou Navigation Satellite System constellation, coming up with a product that can potentially rival the US Global Positioning System (GPS).
• China initiated BeiDou in 1994 with aims to integrate its application in different sectors, including fishery, agriculture, special care, mass-market applications, forestry and public security.
• The name BeiDou comes from Chinese word for the Big Dipper or Plough constellation.
• It consists of 27 satellites in medium Earth orbit, five in geostationary orbit and three more in inclined geosynchronous orbits.
• The navigation satellite system was completed in three steps: BDS-1 which provided services to China, BDS- 2 to provide services to the Asia-Pacific region and BDS-3 which provides services worldwide.
• China’s navigation system uses a network of satellites and can provide positional accuracies of under ten meters (GPS provides positioning accuracies of under 2.2 meters).
• BeiDou offers services including accurate positioning, navigation and timing as well as short message communication.

Other Countries’ Navigation Systems

• The GPS is owned by the US government and operated by the US Air Force.
• Apart from this, Russia has its navigation system called GLONASS, the European Union (EU) has Galileo, while India’s is called Navigation with Indian Constellation (NavIC).

Explanation :

• Scientists in the United States have named the millimetre-wide robots Xenobots (world’s first living machines) — after the species of aquatic frog found across sub-Saharan Africa from Nigeria and Sudan to South Africa,Xenopus laevis.
• Scientists have repurposed living cells scraped from frog embryos and assembled them into entirely new life-forms.

Application

• The xenobots can move toward a target, perhaps pick up a payload (like a medicine that needs to be carried to a specific place inside a patient) — and heal themselves after being cut.

Explanation :

• Microdot Technology involves spraying thousands of the small dots laser etched with a PIN (Personal Identification Number) number, linked to the Vehicle Number, throughout the vehicle. As the polymer dots are 1mm by 1mm it is impossible to locate them.
• These can be read physically with a microscope and identified with an ultraviolet light source.
• The microdots and adhesive fix permanently and cannot be removed without damaging the vehicle itself.

Advantages

• A vehicle, which has microdots sprayed on its body, if stolen, can be easily identified with the help of this technology.
• Similarly, the use of fake spare parts can also be prevented as counterfeit ones can be singled out easily.

Explanation :

• Natural uranium is composed of various isotopes, or different types of uranium. It contains approximately 99.3% of the isotope uranium-238, and has only very small concentrations, about 7%, of the fissile isotope uranium-235. An isotope is considered fissile if it can be split by a slow moving neutron.
• Uranium-235 is the most significant fissile isotope of uranium for reactor fuel and nuclear weapons.
• Uranium needs to be in a gaseous form for enrichment due to the varying chemical and physical properties the different isotopes (U-235 and U-238) have.
• Commercially, the U235 isotope is enriched to 3 to 5% (from the natural state of 0.7%) and is then further processed to create nuclear fuel.
• At the conversion plant, uranium oxide is converted to the chemical form of uranium hexafluoride (UF6) to be usable in an enrichment facility.

Stages of Enrichment

• Uranium enriched to concentrations above 0.7% but less than 20% uranium-235 is defined as low enriched uranium (LEU). Most nuclear reactors use LEU that is about 3-5% uranium-235.
• Uranium enriched to more than 20% uranium-235 is defined as highly enriched uranium (HEU). All HEU is weapons-usable, but the lower the enrichment level the greater the amount of material required to achieve a critical mass - the amount of material required to build a bomb.
• States with nuclear weapons typically use so-called weapons-grade HEU, which is typically defined as 90% HEU or above, to minimize weapons’ size.