My Science School

Nurdles are tiny plastic pellets that form the raw materials of most of today’s plastic products and are made of polyethylene, polypropylene, polystyrene, polyvinyl chloride and other plastics. They are melted down and cast into moulds to make various plastic products. Today, nurdles are rapidly degrading our oceans.

They are the raw material for everything that’s made of plastic. But even if they’re tiny, their damage is giant and immeasurable. Because of their size, it’s hard to keep them contained, and they spill into rivers, waterways, and the ocean. 

Nurdles come in all sorts of colors, and their size and shape make it very easy for marine life to mistake them for food. It’s been recorded that more than 220 species of marine animals ingest microplastics and plastic debris. 

Nurdles are made of polyethylene, polypropylene, polystyrene, polyvinyl chloride, or other plastic types. Also, in some cases, they contain different additives to create pellets of different densities.

Credit :  Ocean Blue

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A precis is a summary of a passage. It covers all the essential points in the passage. It is always shorter than the original passage. As a general rule, a precis should contain one-third of the total number of words in the original passage

Here is a sample passage.

The habit of reading needs to be cultivated. It can be one of the most pleasurable activities of your life. In the bargain, you gain knowledge, vocabulary, expression of ideas, and moral values. However, everyone cannot enjoy reading because it requires a certain level of intelligence, language skill, comprehension skill, interest, and above all, concentration. Reading habits can be best developed in childhood. But unfortunately, reading habits have been replaced by other activities such as watching television, playing video games on mobile phones, or just surfing the Internet. Hence, concentration of students is very less. Students are not able to expand their knowledge as the span of attention is very less. You must know that reading good books can change your outlook. It can expand your intellect. It can make you think. It can add meaning and purpose to your life. You can get inspiration by reading books about great people. It can motivate you to set bigger goals for yourself. The company of books is definitely more rewarding than the company of most other things. Hence you should cultivate the habit of reading and make your mind rich and refined.

Here's the precis of the passage on left.

Reading books enriches you knowledge, vocabulary, language, expression, ideas, and moral values. Not all are capable of reading as it requires some skills. The habit of reading should be cultivated at a young age. We do not gain much by watching television, videos or playing games on the mobile but reading can change the way we think and inspire us to achieve great things in life. Hence make reading a habit.

Tips for precis writing:

• Read the passage carefully
• Gather the theme and the main points in the passage
• Delete unwanted details
• Construct sentences in your own words. Do not copy the actual sentence.
• Put the sentences in a logical and concise manner.
• Choose your words carefully.
• Read the precis to see if all the essential points are covered.

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More than beautiful, monarch butterflies contribute to the health of our planet. While feeding on nectar, they pollinate many types of wildflowers. The flowers they chose are varieties that are brightly colored, grow in clusters, stay open during the day, and have flat surfaces that serve as landing pads for their tiny guests. Monarch butterflies are also an important food source for birds, small animals, and other insects.

The vivid markings of the monarch butterfly (Danaus plexippus) serves as a “skull and crossbones” warning, signaling “Poison!” to the butterfly’s predators. Female monarchs lay their eggs on the underside of poisonous milkweed leaves. As the caterpillar hatches, it eats its own egg; then switches to a diet of milkweed leaves. The milkweeds’ toxins remain permanently in the monarch’s system, even after the caterpillar metamorphoses into a butterfly. Animals that eat a monarch become very sick and, thereafter, will avoid this distinctively patterned butterfly.

Monarch butterflies live mainly in prairies, meadows, grasslands and along roadsides, across most of North America. The adult butterfly drinks nectar from a variety of flowers, uncoiling and extending its long proboscis to sip food. When not in use, this flexible “tongue” coils back into a spiral.

Most monarchs will live only a few weeks, but the generation that emerges in late summer and early fall is different. These butterflies are born to travel and may live for eight or nine months to accomplish their lengthy migration. Scientists think the monarchs use the position of the sun and the changing weather to know when it’s time for their long journey.

Credit : National Park Service

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Dragonfly, (suborder Anisoptera), also called darner, devil’s arrow, or devil’s darning needle, any of a group of roughly 3,000 species of aerial predatory insects most commonly found near freshwater habitats throughout most of the world. Damselflies (suborder Zygoptera) are sometimes also called dragonflies in that both are odonates (order Odonata).

Young dragonflies, called larvae or sometimes nymphs or naiads, are aquatic and are as dedicated predators under water as the adults are in the air. The functionally wingless larvae are usually mottled or dull in colour, matching the sediments or water plants among which they live. They have bulging eyes somewhat similar to the adults, but possess a formidable anatomical structure not present in the adult. Called the “mask,” it is a fusion of the larva’s third pair of mouthparts. Disproportionately large, the mask folds beneath both the head and thorax when it is not in use. At the end of the mask is a set of fanglike pincers used to seize prey such as worms, crustaceans, tadpoles, and small fish. Different species of dragonfly larvae can be described as sprawlers, burrowers, hiders, or claspers. Their shape, metabolism, and respiration differ concordantly with the microhabitat they occupy.

Larvae crawl from eggs laid in or near water. Some species lay their eggs inside plant tissue, others attach their eggs to substrates at or above the water’s surface, and some may drop or wash their eggs from their abdomen onto water. Larvae absorb oxygen from the water using gills inside the rectum. The abdomen draws water in and pumps it out again through the anus. Water can be forcibly expelled in this way, resulting in jet propulsion as a means of escape. Solid waste is also expelled in this manner. As the larva grows, it molts, its future wings first becoming apparent about halfway through the larva’s development. These wing sheaths then enlarge rapidly with each successive molt. Eventually, the larva crawls out of the water (often at night) and molts one last time, emerging as an adult and leaving behind a cast skin (exuvia).

Many dragonfly families have descriptive common names associated with their scientific names. Examples include the hawkers (Aeshnidae), petaltails (Petaluridae), and clubtails (Gomphidae). Numerous other names related to neither taxonomy nor fact have traditionally been applied to dragonflies, such as horse stinger. Dragonflies have also been known as “snake doctors” in the American South, owing to the superstition that they nurse ill snakes back to health. The term devil’s darning needle is derived from a superstition that dragonflies may sew up the eyes, ears, or mouth of a sleeping child, especially one who has misbehaved. In reality, dragonflies present no danger to humans.

Credit : Britannica 

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Seven different species of sea (or marine) turtles grace our ocean waters, from the shallow seagrass beds of the Indian Ocean, to the colorful reefs of the Coral Triangle and the sandy beaches of the Eastern Pacific. While these highly migratory species periodically come ashore to either bask or nest, sea turtles spend the bulk of their lives in the ocean. WWF's work on sea turtles focuses on five of those species: green, hawksbill, loggerhead, leatherback, and olive ridley.

Over the last 200 years, human activities have tipped the scales against the survival of these ancient mariners. Slaughtered for their eggs, meat, skin, and shells, sea turtles suffer from poaching and over-exploitation. They also face habitat destruction and accidental capture—known as bycatch—in fishing gear. Climate change has an impact on turtle nesting sites; it alters sand temperatures, which then affects the sex of hatchlings. Nearly all species of sea turtle are now classified as endangered, with three of the seven existing species being critically endangered.

WWF is committed to stopping the decline of sea turtles and works for the recovery of the species. We work to secure environments in which both turtles and the people that depend upon them can survive.

Credit : World Wildlife Fund

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The red rock crab (aka red crab, rock crab) is similar to -- but smaller than -- the Dungeness. This species usually measures less than 6 inches across the back and is characterized by large claws. Despite being less meaty than the Dungeness, red rock crab meat is also very tasty. It can be distinguished from the Dungeness by the presence of black on the tips of its claws and by its red coloration. The red rock crab also prefers rocky substrates, as the name implies.

The red crab has been described as the “other big crab.” The red crab is one of several related species of crustaceans that live in various deep stretches of the Atlantic. Red crabs flank the edge of the continental shelf from Nova Scotia south to the Gulf of Mexico. Blue crabs are called swimming crabs because they can use their paddle-like rear legs to propel themselves through the water. Red crabs have no choice but to walk along the sea floor. Most live at greater depths than do the king crabs.

At the depths where red crabs live, there is little or no light to navigate, and water temperatures hover around 38 degrees. The red crabs scuttle across the ocean floor at depths from 600 feet to a mile deep. Often the red crabs must rely on food that sinks down from the surface. The carcasses of dead whales sometimes provide a kind of nutrition bonanza that the crabs can sniff out from long distances away.

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Also known as the gnu, the wildebeest is a member of the antelope family. They have a large, box-like head with curving horns. The front end of their body is heavily built, while the hindquarters are slender with spindly legs. They have a gray coat and a black mane as well as a beard that can be black or white. There are several races of wildebeest. The species forming the large herds of the Serengeti-Mara ecosystem of Kenya and Tanzania is known as the western white-bearded wildebeest, while the eastern white-bearded races inhabit Kenya and Tanzania east of the Gregory Rift. The brindled, or blue, race occurs south of the Zambezi River.

Their habitat is threatened by fragmentation, which is caused when land is fenced off for agriculture. While they are widespread and abundant in certain areas, the spread of civilization and agriculture, the reduction of water sources, and poaching are threatening this iconic species’ survival.

These large mammals are continually on the move, as they seek favorable supplies of grass and water. The famous Serengeti population of wildebeest is a very large nomadic group. This group makes a migratory circle of 800 to 1,610 kilometers (500 to 1,000 miles) each year, beginning right after the calving season at the start of the year. They are relentless in their advance and many are injured, lost (especially calves), or killed. By the end of the dry season, the wildebeest have almost exhausted the grazing lands and return to the Serengeti plains as the rains begin.

Credit : African Wildlife Foundation

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Porcupine is a large rodent that lives in Africa Europe, Americas and Asia. It is known for the sharp quills that cover its body. There are over two dozen porcupine species and all of them have these quills. Some porcupines have up to 30,000 quills on their body.

It uses the quills as a defence. These quills typically lie flat until it is threatened. They rise up and deter predators. The quills are easily released when predators get in touch with it. Lost quills are replaced with new quills.

 It is a nocturnal animal, eating leaves, stem, bark and fruit. It lives in tree branches or tangles of roots, and rock crevices. Its home is called a den.

The largest porcupine is the North African crested porcupine. It grows up to 36 inches (90 centimeters) long. The smallest is the Bahia hairy dwarf porcupine. It grows up to 15 inches (38 cm) long. Porcupines weigh 2.5 to 77 lbs. (1.2 to 35 kilograms), depending on species, and their tails can grow up to 8 to 12 inches (20 to 30 cm), according to the San Diego Zoo. The length of quills varies by type. New World porcupines have small quills that are around 4 inches (10 cm) long, while Old World porcupines have quills that can grow up to 20 inches (51 cm) long, though there are some exceptions.

A typical mating ritual consists of two males fighting over a single female. The males are careful not to injure themselves during the fight, and the winner territorially urinates on the female so that she knows to move her tail aside for safe, quill-free mating.

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Octopus is a soft-bodied, eight-limbed molluscs of the order Octopoda. It lives in all the world's oceans. It has a bulbous head, eight arms with suction cups on the bottom and three hearts. The colour of its blood is blue because of the copper-based protein called hemocyanin in the blood.

 It squirts an ink-like liquid to deter predators. This will temporarily blind and confuse a potential attacker, giving him the time to swim away.

It can squeeze into (or out of) tight spaces in search of food and shelter. It diet includes clams, shrimps, lobsters, fish, and even sharks.

Females usually lay 200,000 to 400.000 eggs. They guard the eggs even without eating. Once the eggs hatch, the female octopus dies and so does male octopus within a few months.

Octopuses live in oceans all over the world. Most are pelagic, meaning they live near the water's surface in shells, reefs and crevices. Some species live on the floor of the ocean, making their homes out of caves. Octopuses tend to be solitary, though they do interact with other octopuses at times. Some species of octopuses hunt at night, while others only hunt at dusk and dawn. 

When scared, octopuses will shoot a dark liquid, sometimes called ink, at the thing that scared them. This will temporarily blind and confuse a potential attacker, giving the octopus time to swim away. The ink can also dull the attacker’s smelling and tasting abilities, according to the Smithsonian article.  

Octopuses can also change color to hide and match their surroundings. They can turn blue, gray, pink, brown or green. The mimic octopus can also flex its body to resemble more dangerous animals, such as eels and lionfish, according to the World Animal Foundation.

If an octopus does get caught — no problem. They can lose arms and regrow them, according to National Geographic. 

Octopuses are fast swimmers but they prefer to slowly crawl along the sea bottom. To swim, octopuses suck water into their bodies and shoot it out a tube called a siphon, according to the World Animal Foundation. This lets the octopus blast off, away from attackers. 

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The white dwarf consists of an exotic stew of helium, carbon, and oxygen nuclei swimming in a sea of highly energetic electrons. The combined pressure of the electrons holds up the white dwarf, preventing further collapse towards an even stranger entity like a neutron star or black hole.

The white dwarf now has before it a long, quiet future. As the trapped heat trickles out, it slowly cools and dims. Eventually it will become an inert lump of carbon and oxygen floating invisibly in space: a black dwarf. But the universe isn’t old enough for any black dwarfs to have formed. The first white dwarfs born in the earliest generations of stars are still, 14 billion years later, cooling off. The coolest white dwarfs we know of, with temperature around 4,000 degrees Celsius (7,000 degrees Fahrenheit), may also be some of the oldest relics in the cosmos.

But not all white dwarfs go quietly into the night. White dwarfs that orbit other stars lead to highly explosive phenomena. The white dwarf starts things off by siphoning gas off its companion. Hydrogen is transferred across a gaseous bridge and spilled onto the white dwarf’s surface. As the hydrogen accumulates, its temperature and density reach a flash point where the entire shell of newly acquired fuel violently fuses releasing a tremendous amount of energy. This flash, called a nova, causes the white dwarf to briefly flare with the brilliance of 50,000 suns and then slowly fade back into obscurity.

White dwarfs – the cores left behind after a star has exhausted its fuel supply – are sprinkled throughout every galaxy. Like a stellar graveyard, they are the tombstones of nearly every star that lived and died. Once the sites of stellar furnaces where new atoms were forged, these ancient stars have been repurposed as an astronomer’s tool that have upended our understanding of the evolution of the universe.

Credit : Earth Sky 

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The first woman to travel into space was a Soviet cosmonaut named Valentina Tereshkova. She traveled around Earth 48 times while orbiting in the Vostok 6 spacecraft in 1963. The first American woman to travel into space was Sally Ride who rode onboard the space shuttle Challenger in 1983 and 1984.

Born in the village of Maslennikovo northeast of Moscow, Tereshkova volunteered for the Soviet cosmonaut program after Yuri Gagarin made history as the first man to fly in space on April 12, 1961. She was not a pilot, but had extensive parachuting experience, with 126 jumps under her belt. (Gagarin parachuted to Earth, ejecting from the Vostok capsule during descent as part of the landing sequence.)

Tereshkova was one of four women who received 18 months of training for Vostok 6, and was ultimately selected to pilot the flight. The mission launched from Baikonur Cosmodrome two days after Vostok 5, piloted by cosmonaut Valeriy Bykovsky, with the two spacecraft's coming within 3 miles (5 kilometers) of each other. 

Tereshkova spent 70 hours in space and orbited Earth 48 times during her mission. Though an icon of Soviet space exploration, she never flew in space again and became a test pilot and instructor.

Credit : Space.com

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Yuri Gagarin was the first person to fly in space. His flight, on April 12, 1961, lasted 108 minutes as he circled the Earth for a little more than one orbit in the Soviet Union's Vostok spacecraft. Following the flight, Gagarin became a cultural hero in the Soviet Union. Even today, more than six decades after the historic flight, Gagarin is widely celebrated in Russian space museums, with numerous artifacts, busts and statues displayed in his honor. His remains are buried at the Kremlin in Moscow, and part of his spacecraft is on display at the RKK Energiya museum.

Gagarin's flight came at a time when the United States and the Soviet Union were competing for technological supremacy in space. The Soviet Union had already sent the first artificial satellite, called Sputnik, into space in October 1957.

Before Gagarin's mission, the Soviets sent a test flight into space using a prototype of the Vostok spacecraft. During this flight, they sent a life-size dummy called Ivan Ivanovich and a dog named Zvezdochka into space. After the test flight, the Soviet's considered the vessel fit to take a human into space.

Credit : Space.com

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The Imaging Infrared Spectrometer (IIRS) instrument onboard the Chandrayaan-2 lunar orbiter has confirmed the presence of both hydroxyl ions (OH) and water molecules (H2O) on the surface of the moon.

It has further quantified the amount of water molecules present on the lunar surface regions it imaged, and distinguished parts of the moon that are water-rich from those that are scant in hydration.

Researchers used the data obtained by the Chandrayaan-2 orbiter's imaging infrared spectrometer (IIRS), an instrument that collects information from the Moon's electromagnetic spectrum, to understand the mineral composition of the satellite. They analysed data from three strips on the Chandrayaan-2 IIRS sensor for hydration, which led to "unambiguous detection of OH (hydroxyl) and H2O (water) signatures."

The research findings, published in the journal Current Science, state that hydration absorption was observed at all latitudes and surface types in varying degrees. "The initial data analysis from IIRS clearly demonstrates the presence of widespread lunar hydration and unambiguous detection of OH and H2O signatures on the Moon between 29 degrees north and 62 degrees north latitude," researchers said.

It was also observed from the data that the brighter sunlit highland regions at higher latitudes of the Moon were found to have higher hydroxyl or possibly water molecules. Scientists at the Indian Institute of Remote Sensing (IIRS) in Dehradun opine that the formation of hydroxyl and water on the Moon is due to space weathering, a process of interaction of solar winds with the lunar surface. This combined with impact events lead to chemical changes that further triggered the formation of reactive hydroxyl molecules.

Credit : India Today 

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Mars' moons are among the smallest in the solar system. Phobos is a bit larger than Deimos, and orbits only 3,700 miles (6,000 kilometers) above the Martian surface. No known moon orbits closer to its planet. It whips around Mars three times a day, while the more distant Deimos takes 30 hours for each orbit. Phobos is gradually spiraling inward, drawing about six feet (1.8 meters) closer to the planet each century. Within 50 million years, it will either crash into Mars or break up and form a ring around the planet.

To someone standing on the Mars-facing side of Phobos, Mars would take up a large part of the sky. And people may one day do just that. Scientists have discussed the possibility of using one of the Martian moons as a base from which astronauts could observe the Red Planet and launch robots to its surface, while shielded by miles of rock from cosmic rays and solar radiation for nearly two-thirds of every orbit.

Like Earth's Moon, Phobos and Deimos always present the same face to their planet. Both are lumpy, heavily-cratered and covered in dust and loose rocks. They are among the darker objects in the solar system. The moons appear to be made of carbon-rich rock mixed with ice and may be captured asteroids.

Phobos has only 1/1,000th as much gravitational pull as Earth. A 150-pound (68 kilogram) person would weigh two ounces (68 grams) there. Yet NASA's Mars Global Surveyor has shown evidence of landslides, and of boulders and dust that fell back down to the surface after being blasted off the moon by meteorites.

Credit : NASA Science 

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The Joseph Lister Memorial is a memorial to Joseph Lister, 1st Baron Lister by the sculptor Thomas Brock, situated in Portland Place in Marylebone, London. The memorial is positioned in the centre of the road opposite numbers 71 to 81 and is Grade II listed. It is close to Lister's home at 12 Park Crescent.

The memorial was unveiled by Sir John Bland-Sutton, President of the Royal College of Surgeons, on 13 March 1924. The base of the monument is made of grey Aberdeen granite. On top of the base is a bronze bust of Joseph Lister. At the front are the figures of a woman and a boy: the boy is holding a garland of flowers; the woman is pointing to Lister with her right hand.

Lister’s work had been largely misunderstood in England and the United States. Opposition was directed against his germ theory rather than against his “carbolic treatment.” The majority of practicing surgeons were unconvinced; while not antagonistic, they awaited clear proof that antisepsis constituted a major advance. Lister was not a spectacular operative surgeon and refused to publish statistics. Edinburgh, despite the ancient fame of its medical school, was regarded as a provincial centre. Lister understood that he must convince London before the usefulness of his work would be generally accepted.

His chance came in 1877, when he was offered the chair of Clinical Surgery at King’s College. On October 26, 1877, Lister, at King’s College Hospital, for the first time performed the then-revolutionary operation of wiring a fractured patella, or kneecap. It entailed the deliberate conversion of a simple fracture, carrying no risk to life, into a compound fracture, which often resulted in generalized infection and death. Lister’s proposal was widely publicized and aroused much opposition. Thus, the entire success of his operation carried out under antiseptic conditions forced surgical opinion throughout the world to accept that his method had added greatly to the safety of operative surgery.

More fortunate than many pioneers, Lister saw the almost universal acceptance of his principle during his working life. He retired from surgical practice in 1893, after the death of his wife in the previous year. Many honours came to him. Created a baronet in 1883, he was made Baron Lister of Lyme Regis in 1897 and appointed one of the 12 original members of the Order of Merit in 1902. He was a gentle, shy, unassuming man, firm in his purpose because he humbly believed himself to be directed by God. He was uninterested in social success or financial reward. In person he was handsome, with a fine athletic figure, fresh complexion, hazel eyes, and silver hair. For some years before his death, however, he was almost completely blind and deaf. Lister wrote no books but contributed many papers to professional journals. These are contained in The Collected Papers of Joseph, Baron Lister, 2 vol. (1909).

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