My Science School

Kitti’s hog-nosed bat weighs as little as 1.5 g (1/20 oz) and is 3 cm (just over 1 in) long. It is also called the bumblebee bat. Ecologically, this bat occupies a pretty tiny niche. It only lives in limestone caves along rivers that run through coniferous or deciduous forests. And geographically, this bat is only found in a very small area of Thailand and Burma Probably using a lot of hover hunting, Kitti’s Hog-nosed Bats only forage for food for short windows of time, only about 30 min each evening and 20 min just before dawn, during which it eats small flies and spiders. Since these foraging trips can be easily interrupted by rains and low temperatures it is likely that climate change will have an effect on the foraging ability of this bat. Their restricted range, combined with the human disturbance, habitat destruction and small population size are all contributing to a downward population trend.

 

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Emperors are the largest of all penguins—an average bird stands some 45 inches tall. These flightless animals live on the Antarctic ice and in the frigid surrounding waters. They huddle together to escape wind and conserve warmth. Individuals take turns moving to the group's protected and relatively toasty interior. Once a penguin has warmed a bit it will move to the perimeter of the group so that others can enjoy protection from the icy elements. Emperor penguins spend the long winter on the open ice—and even breed during this harsh season. Females lay a single egg and then promptly leave it behind. They undertake an extended hunting trip that lasts some two months! Depending on the extent of the ice pack, females may need to travel some 50 miles just to reach the open ocean, where they will feed on fish, squid, and krill.  The emperor penguin can dive as deep as 565 m (1,850 ft). It stays underwater for up to 22 minutes as it hunts for prey.

 

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           Many plastic companies assure us that the plastic they produce can be recycled. But this is not always possible. Generally, plastic cannot be recycled more than three to four times.

           Plastics that cannot be recycled usually end up in dump yards. These plastics react with the ground leading to the release of toxic substances which pollute the ground. If they are burned, plastic creates another set of health and environmental hazards. Sometimes, they are thrown away into drainages thus leading to a different issue of waste management.

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           Several man-made substances are carcinogenic, that is, capable of causing cancer to both humans and other animals. Polystyrene is one such material. It is usually used to make food containers, disposable plastic spoons and CD cases.

           To produce polystyrene, we use benzene and styrene. Benzene is a known cancer causing agent while styrene is a probable carcinogen. Scientists, after various lab experiments found out that carbon tetrachloride used in its production are capable of causing cancer to animals.

           Labourers who work in polystyrene production plants are often at increased risk of cancer. Workers subjected to prolonged exposure develop acute liver and kidney failure. Low levels of exposure can also cause dizziness, irritation to eyes, nose and even throat. Also, when you use stirrers and spoons made of polystyrene, styrene migrates out of the stirrer to your drinks like coffee and tea.

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           Where do all your chocolate wrappers go? The waste basket of course. But where do you empty your waste basket? Maybe dump yards, or maybe we don’t know.

           We use a range of products made of different polymers- your notebooks, pencil boxes, water bottles, schoolbags, food packagings, the wrappers of all your belongings and so on. All these have become an inevitable part of our lives. After use, it becomes waste which we finally throw away. The environment cannot handle all the waste that we produce. Most of these wastes harm the earth we live in.

           All polymers except biodegradable ones are not eco-friendly. The non-biodegradable polymers cause trouble to the smooth functioning of our planet. All of you know at least some harmful effects of plastics. Let us now look at how some polymers affect us.

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           You might be using silicone brushes or spoons in your kitchen. Though they have a soft texture, they are used for cooking which generally involves high temperatures. Ever wondered why?

           Silicone is resistant to heat. It is a non-toxic substance that shows resistance to water and chemicals as well. Because of these reasons, silicone is preferred to make kitchen ware.

           Silicone is a polymer made of the repeating units of siloxane – silicon and oxygen atoms-, carbon and hydrogen. Sometimes, other elements like methyl or benzene are also used with these.

          Silicone has a wide range of uses. It is used as a solvent for dry-cleaning as an alternative to chlorine because it has less impact on the environment. Many of the electronic appliances have cases made of silicone. It is also used in the aerospace industry because of its various desirable qualities.

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           Have you seen the blood and urine bags used in hospitals? They are flexible and waterproof at the same time. These bags can only be used once and are made of medically approved PVC.

           PVC is cost-effective, transparent and light in weight. It is soft and tear resistant at the same time. All the IV bags and medical tubings are made of medically approved PVC. It is also used to make other products like bags to collect blood, catheters, heart-lung bypass sets and dialysis sets. Almost one third of plastic-based medical devices are made from PVC.

            In fact, 85,000 tonnes of PVC are used for medical purposes in Europe alone.

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           Polyester is a popular choice of clothing. All of you might have at least one polyester outfit. It has a bright colour and a silky touch. The cloth is very slippery as well.

          Polyester fabric is extremely strong. It is durable and won’t shrink. Polyester does not wrinkle easily which solves the problem or ironing. Polyester does not get stained easily. It is easy to wash and quick to dry. What more is needed for a fabric for rough use?

           The most popular and one of the earliest uses of polyester was to make polyester suits. It can also be folded into permanent pleats and decorative shape.

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           You might have seen petri dishes in your biology lab. When you see a petri dish again, remember that it is made of a polymer known as polystyrene. Polystyrene is a plastic that is used to make a variety of consumer goods. It is hard and is usually used to make laboratory equipment and food packaging.

           Several additives are added to polystyrene to make it suitable for the production of things like electronic appliances, automobile parts, toys, gardening pots and surf boards.

           Polystyrene is made by polymerizing styrene monomers. Some amount of styrene is present in nature as well: in strawberries, cinnamon and coffee. It is easy to sterilize polystyrene. Therefore, it has a wide range of medical applications, including tissue culture trays, test tubes and medical devices.

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           The first thing that comes to our mind when we hear the name PVC is the water pipes in our house. But, PVC is used to make a lot of other things as well.

           PVC shows good resistance to water. Because of its waterproofing traits, it is used to make rain-coats, shower curtains and water pipes. Its weather resistance is the reason why it’s used to make coats, jackets and sports bags. PVC also shows good flame resistance because of its chlorine content. When PVC catches fire, the chlorine atoms present in it are released and these atoms block burning. PVC is available in two forms- rigid and flexible. The rigid form of PVC is used to make doors, windows, and ATM cards. Flexible PVC is mainly used for plumbing and insulation.

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           HDPE and LDPE are two grades of thermosetting plastics made of ethylene monomers, whose properties differ from one another based on their structure.

           HDPE has a higher density. Therefore, it is harder, has a higher chemical resistance and can withstand higher temperatures. It has little branching resulting in higher strength and stronger intermolecular forces. It is used to make things like bottle caps, corrosion protection for steel pipes, folding chairs and tables, chemical resistant pipes, plastic bags and water pipes.

           On the other hand, LDPE is softer, more flexible and melts at a lower temperature than HDPE. Its strength is lower compared to that of HDPE.

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