Day-392 | Daily MCQs | UPSC Prelims | SCIENCE AND TECHNOLOGY

Answer: D
Explanation:
• Plastic is a polymeric material that has the capability of being molded or shaped, usually by the application of heat and pressure. This property of plasticity, often found in combination with other special properties such as low density, low electrical conductivity, transparency, and toughness, allows plastics to be made into a great variety of products.
• Many of the chemical names of the polymers employed as plastics have become familiar to consumers, although some are better known by their abbreviations or trade names. Thus, polyethylene terephthalate and polyvinyl chloride are commonly referred to as PET and PVC, while foamed polystyrene and polymethyl methacrylate are known by their trademarked names, Styrofoam and Plexiglas (or Perspex).

Answer: B
Explanation:
A drone equipped with a thermal camera was used by the Forest Department authorities recently to spot the leopard that is on the prowl, at Ukkalagere Betta in T. Narsipur taluk of Mysuru district.
All objects emit infrared energy (heat).
• In general, the hotter an object is, the more radiation it emits.
• A thermal imager (also known as a thermal camera) is essentially a heat sensor that is capable of detecting tiny differences in temperature.
• The device collects the infrared radiation from objects in the scene and creates an electronic image based on information about the temperature differences.
• Because objects are rarely precisely the same temperature as other objects around them, a thermal camera can detect them and they will appear as distinct in a thermal image.
• Thermal images are normally grayscale in nature: black objects are cold, white objects are hot and the depth of gray indicates variations between the two.
• Some thermal cameras, however, add color to images to help users identify objects at different temperatures.
• They can be used to search for victims outdoors on a cool night, spot smoldering fires inside a wall, or detect overheating electrical wiring.

Answer: C
Explanation:
A new ozone hole has been detected over the tropics, at latitudes of 30 degrees South to 30 degrees North, a recent study claimed.
• The Dobson Unit is the most common unit for measuring ozone concentration.
• Satellite sensors and other ozone-measuring devices, whether on the ground or in the air, help relay regular information about ozone concentrations over the Antarctic region. It provides the basis for monitoring changes in the ozone level.
• The measurement is made and expressed in Dobson units, thanks to the use of the “Dobson spectrophotometer” — a ground-based instrument that measures changes in atmospheric ozone.
• Explaining a Dobson unit, the American space agency’s NASA Ozone Watch says, “a column of air with an ozone concentration of 1 Dobson Unit would contain about 2.69×1016 ozone molecules for every square centimeter of area at the base of the column.”
• The average thickness of the ozone layer is about 300 Dobson units or a layer that is 3 millimetres thick.
• Historical data shows that 1979 was a point of deviation from normal ozone layer size. It was after this year that the average amount of ozone over the Antarctic fell unprecedentedly below 220 Dobson units.

Answer: A
Explanation:
Recently, a tyre exploded on a SpiceJet Delhi-Mumbai aircraft as it touched down at the airport.
• Aircraft tires are filled with nitrogen because nitrogen gas is mostly inert, meaning that it requires more energy to react with other substances. This is important because, at elevated temperatures, oxygen can react with rubber. Oxidized rubber is weaker than non-oxidized rubber, and weaker tires are not preferred.
• Air has certain moisture content and it is generally very hard to remove this moisture. If airplane tires were filled with air, at the flight altitude ice would form inside the tires since the temperature up there is about -30 degrees F. Landing with a chunk of ice in the tire would make it out of balance and change the tire pressure. Tires would probably burst.
• On the other hand, nitrogen doesn’t form a liquid till -173C and pure nitrogen has almost no moisture. It forms liquid only below a very low temperature
• Nitrogen being lighter than air does not play a part in it being used in the airplane tyres.

Answer: A
Explanation:
A four-year-old’s case of antimicrobial resistance (AMR) to most antibiotics has once again brought to fore the dangers of unregulated use of antibiotics creating resistant bacteria that wreak havoc once they enter a body, more so in case the victim’s a child.
● WHO (World Health Organization) recently released the first-ever report on the pipeline of the vaccines currently in development to prevent infections caused by antimicrobial-resistant (AMR) bacterial pathogens. WHO’s analysis points to the need to accelerate trials for AMR related vaccines in late-stage development and maximize the use of existing vaccines. The analysis identifies sixty-one vaccine candidates in various stages of clinical development, including several in late stages of development to address diseases listed on the bacterial priority pathogens list, which WHO has prioritized for R&D.
● The silent pandemic of antimicrobial resistance is of major growing public health concern. Resistant bacterial infections alone are associated with nearly 4.95 million deaths per year, with 1.27 million deaths directly attributed to AMR. But AMR is about more than bacterial infections. AMR occurs when bacteria, viruses, fungi, and parasites change over time and no longer respond to medicines. When an individual becomes infected with these microbes, the infection is said to be resistant to antimicrobial medicines. These infections are often difficult to treat.
● Vaccines are powerful tools to prevent infections in the first place, and therefore have the potential to curb the spread of AMR infections. The AMR vaccine pipeline report aims to guide investments and research into feasible vaccines to mitigate AMR.
● India’s medical societies adopted the Chennai Declaration, a set of national recommendations to promote antibiotic stewardship. The Chennai Declaration calls for urgent initiatives to formulate an effective national policy to control the rising antimicrobial resistance, including a ban on over-the-counter sale of antibiotics, and to bring about changes in the medical education curriculum to include training in antibiotic usage and infection control.