How is nylon made?

Nylon was the first of man-made synthetic fibres, and is considered one of the most important chemical discoveries because of its hardness, resistance, elasticity and resistance to oils and fats.

In the late 1920s and early 1930s, DuPont chemists first created nylon by combining chemicals extracted from coal, water, air, oil, natural gas and agricultural by-products.

The thousands of nylon products on the market today start out as the same at first. Factories combine the chemicals that produce nylon, first heating them to remove the water. The small molecules of each chemical are combined when heated to form larger molecules in a process called polymerization.

The nylon coming out of the heat machine is a flat ribbon. When this tape cools, it hardens. It is then cut into pieces, which are then sent to factories where they are melted and used to make thousands of different products, including parachutes, socks, tires, carpets, gears, machine parts, bearings, furniture, and hair brushes.

Nylon threads used in fabrics, fishing lines, and surgical threads are made when molten nylon passes through the tiny holes in a machine. These threads harden when they touch the air.

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How do harmful bacteria differ from beneficial bacteria?

Bacteria are small unicellular organisms found almost everywhere, in the deepest oceans, beneath the ground, and up to 27,000 meters in the atmosphere. There are many types of bacteria, some causing lethal diseases, while others, on the contrary, are beneficial to man.

Those that are harmful cause diseases in humans, animals and plants. They can spoil food, and even intoxicate the people who eat it.

But there is a large amount of bacteria that man and nature itself use for their benefit. For example, bacteria play an important role in making butter, sauerkraut, yogurt, cheese, and vinegar, all by a chemical change called fermentation. Bacteria attack dead plants and animals, and eventually turn them into food for the soil.

Bacteria are also used to purify water in wastewater treatment plants!

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How is tough glass made?

The glass plate on a car's windshield has an ingredient added to ordinary glass to turn it into safety glass. The glass is constructed with two separate layers, something like a sandwich. Between each layer of glass there is a plastic filler that joins them in a process called lamination.

Even if the outer layer of glass were to break, the inner plastic layer would simply extend due to its elasticity, and keep the broken glass pieces together.

Fire glass with wire is a safety glass with a wire net between two layers of glass. It can withstand fire, and not break easily. Many schools and factories use this type of wired glass.

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How does electricity reach our homes?

Electricity enters our homes, schools, factories, warehouses through copper cables from powerful generators in power plants.

These plants burn coal or oil, or use nuclear reactors or the power of waterfalls to produce the energy needed to run the generators.

Powerful loads of current come from these generators and are reduced by transformers before they reach our homes and factories.

The electrical current produced is a continuous flow of small particles called electrons. This flow of electrons can be activated or deactivated by means of switches. When you turn on an electric light switch, a television, or any other appliance, the electric current is given a message to start flowing. When the switch is lowered, the current flow stops.

Sometimes that current flow stops without touching the switch. This occurs when wires or circuits overload when there is too much electricity, and a device or fuse in the house automatically breaks the circuit to prevent damage to the wires or even a fire in your home.

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How is a pencil made?

The material that makes a pencil write is a mixture of graphite (a form of carbon), clay, wax, and chemicals.

To make a pencil, you have to mix graphite, clay, and water at high speeds. The mixture is placed in a machine that compresses it into a long, thin black wand. This wand or stick is cut into pieces the size of a pencil in length, and then baked until hard. A layer of wax is applied to the pieces so that they write smoothly.

The hardened graphite sticks are placed inside the grooves of a piece of wood. Then another piece of wood with similar grooves is placed over the first piece containing the graphite sticks and joined together in the form of a "sandwich". The two already joined pieces are cut into individual pencils, varnished, sanded and a metal ring is added where the eraser is located.

When sharpening a pencil, wood is actually being removed to expose more of the graphite. When someone writes, tiny fragments of the soft graphite remain on the paper, creating words and images.

Colored pencils are made in the same way, except that other pigments and dyes are mixed with the clay, instead of graphite.

Ancient Greeks and Romans used lead pieces to write!

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How do you submerge a submarine?

A submarine has several large tanks inside that are filled with air when the ship is floating on the surface of the water. It is the air, which is lighter than water, that keeps the submarine afloat, just like any other type of ship.

However, these deposits are different from those of vessels floating on the surface; in submarine deposits there are gates at the top and bottom. These gates, called valves, can be opened to allow seawater or air to enter.

When the lower valve opens, seawater fills each tank, and the air that was in the tank is forced out through the other valve at the top. Already with the interior filled with water, it increases the weight of the submarine and causes the ship to dive.

In order to bring the submarine back to the surface once again, pumps are used to draw the water out of the tanks, and air is blown back in. This new air is the compressed air that has been stored in large metal containers, which is injected into the tanks at high pressure. Again with the tanks full of air, the submarine is raised.

A submarine can dive to a depth of 30 meters in less than a minute. Some of the research submarines are designed to dive to depths of 1,500 meters. These submarines have thick steel hulls to withstand the immense water pressure at that depth.

History was made in 1960 when the submarine Triton traveled around the world in an underwater voyage of 66,500 kilometers in 84 days.

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How does glue bind things together?

Glues, such as paste or cement, are characterized by joining things together. These materials are known as adhesives because they make things stick together. However, their stickiness is not all they have.

For an adhesive to be practical, it must transform from a smooth liquid to a hard solid in a short period of time. Sticky substances such as honey, syrup, and chewing gum are not good adhesives because they take a long time to harden.

If we were to study any solid body under the microscope, we would realize that what we believe to be perfectly smooth has roughnesses and spaces.

Suppose we are making a model that requires the union of two pieces of wood. We have to apply the adhesive to one of the surfaces and place the other piece of wood on top of it.

What the glue does is cover all those little roughnesses and holes in the wood. When it dries and hardens, the two surfaces are firmly together.

Some adhesives are made from the skin, bones, and tissues of animals and fish!

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How can an x-ray see inside the human body?

X-rays are like ordinary rays of light, except for one thing, they have a shorter wavelength. Because of this, a beam of this length has more energy and will be more penetrating than a simple beam of light, even through solid substances such as wood, metal and concrete.

An X-ray machine has a high voltage current flowing through X-ray tubes. Inside each tube is an airtight glass container. Inside it are two electrodes, or terminals, one negative and one positive. The negative is called a cathode. It is a tungsten coil that is heated by an electric current causing it to release electrons, or charged particles.

These electrons travel from the cathode to the anode, or positive, at very high speeds, from 96,000 to 282,000 kilometers per second. The anode, also called the target, is usually a tungsten block.

The anode stops the fast electrons. Some of the energy of the electrons is transformed into heat and the rest into X radiation. This X radiation, or X-rays, escapes through a window of the tube and goes to the part of the body that is going to be x-rayed.

Since these X-rays pass through the body, they cast shadows on a piece of photographic film, much like the film used in an ordinary camera.

In the hands of qualified technicians, X-rays can help save lives by killing cancer cells, helping doctors spot broken bones and diseased organs in a person's body, and even sterilizing medical supplies that cannot be boiled.

X-rays are also used in commerce and industry to locate product defects and to examine luggage at airports. But X-rays can also cause harm to humans by destroying healthy tissue, causing cancer and skin burns, and even modifying genes that pass traits from one generation to the next.

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What is the function of sonar?

The sinking of the British liner Titanic in 1912, after hitting an iceberg, spurred scientists to find a way to detect obstacles underwater. British and American forces used a form of sound detection against submarines in World War I. Scientist Paul Langevin created the sonar that uses the echo of emitted sounds.

Today, echo pickup is used in navigation to determine water depth, to locate fish shoals, and in marine research and ocean floor mapping. The sound pulses are emitted through the water and their echoes are reflected back to the boat by any obstacle 10 km away. The received signals are displayed on a video screen.

The sound travels in the water at about 1,500 m per second. The distance to the obstacle is calculated by the time it takes for the echo to return, and the Doppler effect of the sound waves shows if the object is moving.

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How do divers breathe underwater?

Aqua-lung

Since the nineteenth century men of science had tried to create an artifact that would allow divers to breathe without relying on the outside air supply. But it wasn't until 1943 that French navigator Jacques-Yves Cousteau and his colleague Emile Gagnan invented aqua-lung (self-contained breathing apparatus). Cousteau used it to dive to a depth of 60 meters.

The lungs do not have enough capacity to expand when the water pressure increases rapidly with depth: at 10 meters it is 2 atmospheres (2 kg/cm²).

In order for a submerged diver to breathe, he must receive air at the same pressure as the surrounding water. This is achieved with aqua-lung. The air is stored at high pressure - up to 200 atmospheres - in tanks that are carried on the back, from which a tube connected to a nozzle comes out.

The air reaches the diver through a two-stage regulator. First the pressure is reduced to about 10 atmospheres above the water pressure. The nozzle then supplies air at the same pressure as the secondary water.

The nozzle has a flexible nozzle open to the water on one side and to an air chamber on the other.

The moment the diver inhales, he pulls in the diaphragm, which in turn presses a lever inside the chamber. This opens a valve that lets air in from the tube, where the pressure drops.

When the diver stops inhaling, the opposite happens: the air that reaches the chamber pushes the diaphragm, closes the valve and cuts off the air flow.

Even if the diver does not inhale, the increase in water pressure as it drops pushes the diaphragm forward to open the valve and then let air through the tube.

In this way, the air in the chamber is always maintained at the same pressure as the surrounding water.

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How are bricks made?

The first building materials used by man were made of wood and stone. But the use of bricks followed soon, even before the first writings of history. Today bricks are still one of the main building materials.

What is the material with which bricks are made? Simple earth.

Many natural forces - such as climate, glaciers, volcanoes and chemical reactions - eventually undo the rocks, producing a kind of fine-grained earth called clay. Clay is very manageable when wet, and can be molded into any shape. A brick is made by wetting the clay, pressing it into a mold, and finally baking this clay in a kiln until it hardens.

Currently most bricks are made by machines, which place the clay in large columns, which are cut into pieces with the desired brick sizes.

Most common bricks are red due to the iron oxides in the clay used to make them. Adding other substances to the clay produces bricks of other colors.

The largest brick factory in the world, in England, can produce 16 million bricks in a week.

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What is margarine made of?

The margarine that many people prefer to use instead of butter is made from vegetable and animal fats, along with skim milk and salt. Fats make up 80% of margarine, while milk and salt make up the remaining 20%.

Margarine was invented by a French chemist during the 1860s. Most margarine sold in the United States is made from vegetable oils, such as soybeans, cottonseed, peanuts, or corn oil.

Melted fats are beaten together with milk, cooled to form a solid, then shaped into special machines and packaged as margarine for distribution.
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What is nylon?

  Nylon is an artificial material made from air, coal, water, and petroleum and plant chemicals. Unlike cotton which grows on a plant, nylon is made in a laboratory or factory.
  Because nylon is strong, it is used for rugs, tubing, fishing lines and parachutes. Broad fibers of nylon make long-wearing brush bristles. It stretches well and thus makes stockings that fit readily.
  Nylon was developed in 1938 by a chemist, Dr. Wallace H. Carothers at Du Pont Company. He combined two organic chemicals— hexamethylene-dlamine and adipic acid by forming polymers of them. Du Pont engineers then had to devise ways to produce in quantity these two, formerly rare chemicals. They finally succeeded in making them from common materials (gases of air, etc.).
  To carry on the synthesis, the two compounds are heated by steam, then put under pressure. The semisolid nylon comes out as a flabby sheet that is ice-cooled to barden it.
  It can next be chopped into bits and stored. Fiber is made from the bits by reheating and thus melting them in an oxidation-preventing atmosphere (as in nitrogen gas). This melted nylon is forced through fine holes to come
out as fibers. A twisting and stretching process then lines up the nylon molecules to give a strong final product.