My Science School

Seals can sleep with half of their brains up and working with the other half completely asleep. This is called 'unihemispheric slow-wave sleep'. It gives a whole new meaning to the term 'sleeping with one eye open' as on the side of the brain that is asleep, the eye will close, and on the side that is awake the eye will be open!

This sleep occurs while they are in the water, but when they come up to sleep on land, they sleep with their whole brains turned off like humans.

The study's first author, University of Toronto PhD student Jennifer Lapierre, made this discovery by measuring how different chemicals change in the sleeping and waking sides of the brain. She found that acetylcholine -- an important brain chemical -- was at low levels on the sleeping side of the brain but at high levels on the waking side. This finding suggests that acetylcholine may drive brain alertness on the side that is awake.

But, the study also showed that another important brain chemical -- serotonin -- was present at the equal levels on both sides of the brain whether the seals were awake or asleep. This was a surprising finding because scientist long thought that serotonin was a chemical that causes brain arousal.

These findings have possible human health implications because "about 40% of North Americans suffer from sleep problems and understanding which brain chemicals function to keep us awake or asleep is a major scientific advance. It could help solve the mystery of how and why we sleep" says the study's senior author Jerome Siegel of UCLA's Brain Research Institute.

Credit : Science Daily 

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Eigengrau (German for intrinsic grey) is the term for the colour seen by the human eye in perfect darkness. Also called dark light or brain grey, it is perceived as lighter than black. Even in the absence of light, some action potentials are sent along the optic nerve, causing the sensation of a uniform dark grey colour.

Let’s try to understand as to how humans perceive darkness with a little experiment.  Pick a black object in front of you and stare at it for about a second. Now close your eyes for a few seconds and allow them to adjust.

You may need to cover your eyes if you are in a bright room or outside. Now open them quickly and look at that black object. Now it may take you a few tries to fully see it, but you’ll soon notice that the black object appears darker than the black of total darkness.

When our eyes are open, the light-sensitive layers of cells at the back of our eyeballs called the retina are bombarded by packets of light energy called photons.

The photons are a kind of elementary particle. Or, perhaps they are the quantum of the electromagnetic field that includes electromagnetic radiation like the light. They are also the force carrier for the electromagnetic force. The photons have zero rest mass. They always move at the speed of light within a vacuum condition.

The photons represent visuals like a trigger nerve impulses on the retina that pass through the optic nerve to the brain and a visual image is formed on the retina.

When we close our eyes or enter total darkness most people see vague grey field usually composed of changing regions of tiny black and white dots.

This colour is called the Eigengrau, a German word that means intrinsic grey. What we are seeing is visual noise and it is the static of our retina.

Credit : STSTW Media

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Aluminium is the most abundant element found in the crust of the Earth. It was first discovered by Hans Christian Oersted, a Danish physicist and chemist in 1825. And later, it was discovered by Friedrich Wohler, a German chemist in 1827. But Wöhler’s method could not produce aluminium in great quantities and the metal continued to be a rare metal. In fact, it was costlier than gold. As a result, aluminium was regarded highly at that time. There is a popular story that Napoleon, the famous French emperor, used aluminium knives and forks, while others at the table used silver tableware. It is also said that the King of Thailand once used an aluminium bracelet.

Aluminium is mostly used in the production of construction materials and kitchen utensils. In 1886, Paul Héroult, a French engineer, and Charles Martin Hall, an American engineer, independently electrolyzed a mixture of molten bauxite and cryolite to produce aluminium. This laid the foundation for large-scale production of the metal in later years. After this, two aspects of aluminium changed completely: firstly, it could be mass-produced and was no longer considered as a precious metal; secondly, the mass production of aluminium led to its widespread use in making of industrial and domestic products, which gradually replaced the use of other metals like steel and copper.

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Silicon, atomic number 14, is a chemical element with the symbol Si. In 1787, Antoine-Laurent de Lavoisier first discovered that this metal was present in rocks. He was a French chemist. In 1800, Sir Humphry Davy mistook silicon to be a compound. Later, in 1811, Joseph Louis Gay-Lussac and Louis Jacques Thénard, two French chemists, prepared impure amorphous silicon by heating potassium with silicon tetrafluoride and named it silicon based on the Latin word silex, which means meteorite.

Silicon has very specific uses. High-purity monocrystalline silicon is a semiconductor material, which can be made to produce solar cells that convert radiation energy into electrical energy. This discovery is highly promising in the development of energy.

Silicon can also be made into cermet composites. These composites are resistant to high temperatures, are very tough, and can be cut. They inherit the advantages of metals and ceramics, and also lack the disadvantages of both, a feature that can be applied in weapons manufacturing and aerospace technologies. Pure silica is also used to manufacture high transparency glass fibre for optical fibre communication.

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Hennig Brandt is often credited for the discovery of phosphorus, and there is a very interesting story behind the discovery of this element. One night, in his laboratory, Brandt was attempting to create the Philosopher’s Stone, an elusive goal that was chased by numerous alchemists from time immemorial. The Philosopher’s Stone is said to transform base metals into gold! The year was 1669.

Brandt was heating a mixture of sand and charcoal with a tar like substance produced by boiling down about 1,200 gallons of urine for over two weeks. He then kept this mixture at the highest temperature his furnace could produce. He had spent most of that day in his laboratory, and after many hours a white vapour formed, which condensed into thick drops. What was exciting was that these drops gleamed brightly for hours. Brandt called this glowing, waxy substance phosphorus, a Latin term for things that give off light. This was a completely new thing to be discovered at that time.

In Brandt’s era, the world was believed to be made up of four elements: fire, air, water, and earth. So, like his colleagues to whom he showed his new compound, Brandt also assumed that it was composed of these elements. (It was only after about a hundred years later that Antoine Lavoisier replaced this worldview with another idea that elements were simple substances, which cannot be further isolated.) Anyhow, Brandt’s phosphorus was a spectacular sight, which is immortalized by Artist Joseph Wright of Derby in his painting The Alchemist.

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Two British chemists, Sir William Ramsay and Morris W. Travers discovered neon in 1898. Ramsay chilled a sample of air until it became a liquid, and he then heated this liquid to capture the gases that boiled off. Over a period of six weeks, Ramsay and Travers isolated the remaining gases in order of abundance; nitrogen, oxygen, and argon were already identified by then.

First, krypton was discovered, but once it was removed, they were left with a gas that produced brilliant red light under spectroscopic discharge. This gas was neon, and it was given its name by Ramsay’s son. The term neon comes from the Greek word novum, which means new.

Neon is the fifth most abundant element in the universe after hydrogen, helium, oxygen, and carbon. It is a noble gas with the atomic number 10. Under standard conditions, it has two third density of air and is colourless, odourless, inert, and monatomic. Large volumes of neon are formed during the alpha capture fusion process that occurs in stars. Neon is also used in lighting, popularly called the ‘neon lights’.

Neon is rarely found on inner terrestrial planets like Mercury, Venus, Earth and Mars because of its highly volatile nature. It is also incapable of forming compounds that can become solids. As neon is lighter than air, it escapes from the Earth’s atmosphere.

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The discovery of sodium is perhaps the most delicious discovery so far. Imagine not having salt in our food! How unappealing it would be!

Sodium is a crucial element that forms common salt or NaCl. Here Na refers to sodium and Cl refers to chlorine, the two atoms that combine to form salt. Although we have used salt for centuries, the scientific discovery of sodium happened only in 1807 as sodium is a highly reactive metal that is hard to isolate.

It was Sir Humphry Davy who discovered sodium (Na) in his laboratory. He used electrolysis to remove it from melted caustic soda and identified that it was a metal. Since pure sodium can cause flames upon reacting with water, Davy had to figure out a moisture-free environment for isolating sodium. In the chemical process of electrolysis, it is the electric currents that create chemical changes.

Sodium is an alkali metal. It is soft and flammable in nature. It appears in a silver-white colour in its pure form. The commonly used compounds such as table salt and baking soda contain sodium. Sodium is an essential element in animals as it regulates a number of body functions.

The English word soda is often considered as the root word from which sodium got its name. The name is also linked to sodanum, a headache remedy, from Medieval Latin. The symbol for sodium on the periodic table, Na, comes from the Latin word ‘natrium,’ which means sodium carbonate.

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