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Why does stainless steel remain stainless?

Actually, stainless steel does get stains that may be hard to remove. But ‘stain’ here refers to rust, which is something stainless steel rarely catches. Ever wondered why?

Why steel rusts

Steel is an alloy of iron and carbon. The carbon (which is less than 2% of the material) in the steel makes it harder than ordinary iron. But the iron in it is susceptible to rusting. When there’s moisture in the air, iron atoms in steel react with oxygen to form iron oxides. These deposit on the surface as the red spots we call rust.
If you wash a rusted vessel in water, or scrub it with a scouring pad, some of the rust will come off. This leaves the iron below the surface now exposed to air. Again it will react to form more rust. Over time, the rust will go very deep into the vessel, and it may break.
If you use any steel items at home, it’s important to keep them dry. Even if you wash them, you must wipe them dry; don’t let them dry in the air.

Why stainless steel doesn’t rust

Stainless steel is a different kind of alloy. Along with iron and carbon, it also has nickel and chromium in it. Nickel and chromium have an interesting difference in chemistry, compared to iron.
They too, react with oxygen to form their oxides. But there is a major difference. These oxides are very sticky, and they form a thin film around the stainless steel vessel. They do not dissolve in water, and do not come off even if you scrubbed the dish hard with a scouring pad.
Because of this, once a thin layer of oxide has covered the vessel, the rest of the material will be cut off from the air. It will therefore never rust, and remain as strong as ever.

Chrome Plating

Nickel and chrome are often alloyed with other metals. These are used to make things that are subject to heavy wear and tear, and also are at risk from oxidation in the air. Making them from nickel or chrome alloy prevents oxidation, and also adds extra hardness.
That’s why coins which pass from hand to hand, are often made of nickel alloy. Car and truck wheels, which face a lot of dust, are often made from chrome alloys. Look around you, what objects can you see that are made of chrome or nickel alloys, including stainless steel?

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Why are people’s fingers marked during elections?

Whenever an election comes round, you’ll see that people who voted have an ink mark on their fingers. Why do they get it, and why does it not rub off?

 

Keeping track of who voted

In a democratic country, citizens get to vote in an election to choose their rulers. As all citizens are equal, each citizen is allowed to vote only once in an election. But how does one make sure someone doesn’t cheat and votes more than once?
A simple way is to mark everyone who has voted. Then the mark will show and the person cannot vote again. But what kind of mark does one put?
A mark that rubs off quickly is useless. But it must go off in the time the next election comes, so that the voter can vote again. So what we need is a mark cannot be rubbed off for sometime, but will wear off by the time the next election comes. What chemical can make a mark like that?

Have an election in class to choose your class leader. Use a piggy bank as the ballot box, and make small squares of paper for the ballots. Everyone has to secretly write the name of the person they want to choose as class leader, fold the paper and put it in the ballot box. Ask your chemistry teacher to help you with a little bit of silver nitrate solution from the lab. After each person has voted, dip a glass capillary into the silver nitrate and put a dot on their finger. Hold the finger till it dries. When everyone has voted, you can open the ballot box and count who got the most votes.

Why Silver Nitrate

Silver nitrate is just the chemical we need. It is soluble in water, so you can make an inky black solution. It comes in bottles with a brush in the lid (like nail polish bottles). When you go to vote the first time, you’ll see the election officer draw a thin line over your index finger and its fingernail with the tiny brush. Then they’ll hold your finger till the ink dries, giving you a violet mark.
When it is put on skin, it reacts with the salt present on it to form silver chloride. Silver chloride is not soluble in water, and clings to your skin. It cannot be washed off with soap and water. Not even hot water. Not even if you use alcohol, nail polish remover, or bleach. (But please don’t try these things, they are dangerous.) But as new skin grows and the old skin sloughs off, the ink stain will disappear. The ink on the skin goes off in a week. The ink on the nail takes longer, as the nail grows out.
The ink only works if it dries. If you rub it off while still wet, it will go off.

Supermoon blamed for stranding five ships in Solent

Speculation that the "supermoon" may have caused the Japanese earthquake was dismissed by Nasa – but now British coastguards say it could be behind the stranding of several ships.

Revellers stand beside St. Michael's Tower on Glastonbury Tor watching the moon as it is at its closest point to the Earth for almost two decades Photo: 

Yesterday afternoon five different vessels got into distress in the busy shipping lanes of the Solent, at the Needles on the western side of the Isle of Wight.

Coastguards suggested that they were caught out by Saturday evening's "supermoon", which caused sandbanks to be exposed by low tides.

One of the ships was the 2,900-tonne cargo ship Paula-C, on its way to Cowes with a crew of nine. They were forced to wait for a high tide to lift them clear of a shingle bank.

A 25-foot yacht ran aground and three other vessels were also marooned on sand and shingle banks that normally lie submerged.

A spokesman for the Coastguard said: "We checked them all and there were no injuries, just some surprise at being caught out like this. Blame it on the moon."

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Dr. Nano, also known as Dr. Murali Sastry, is one of the world's top 15 nanobiotechnologists.

Dr. Nano is very passionate about conserving the environment. He is interested in creating industrial materials processes that are eco-friendly. A very hard worker, he has published over 300 papers, and holds 15 Indian and US patents. In 2003, he won the Shanti Swarup Bhatnagar Prize, which is India's highest prize for science. Hard work always pays off!

Like to meet him? You can find him at at Tata Chemicals Innovation Centre in Pune, where he is the Chief Scientist.

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What is a Solar Prominence?
A solar prominence (also known as a filament when viewed against the solar disk) is a large, bright feature extending outward from the Sun's surface. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's hot outer atmosphere, called the corona. A prominence forms over timescales of about a day, and stable prominences may persist in the corona for several months, looping hundreds of thousands of miles into space. Scientists are still researching how and why prominences are formed.

The red-glowing looped material is plasma, a hot gas comprised of electrically charged hydrogen and helium. The prominence plasma flows along a tangled and twisted structure of magnetic fields generated by the sun’s internal dynamo. An erupting prominence occurs when such a structure becomes unstable and bursts outward, releasing the plasma.

“It is not uncommon for prominence material to drain back to the surface as well as escape during an eruption,” states Holly Gilbert a Goddard solar physicist. “In fact, it’s a little strange when ALL of the mass escapes. Prominences are large structures, so once the magnetic fields supporting the mass are stretched out so that they are more vertical, it allows an easy path for some of the mass to drain back down.”

When a prominence erupts, the released material is part of a larger magnetic structure called Coronal Mass Ejections (CMEs). When directed toward Earth, CMEs can interact with our Earth’s magnetic field and trigger a geomagnetic storm, with bright auroras and the potential for disturbance in communications and electrical power networks.

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Distant galaxy helped relight the universe

The discovery of a small but distant galaxy 12.8 billion light years from Earth is providing important clues about the earliest years of the universe's life. By measuring the age of the galaxy's stars, astronomers in Europe and the US say the galaxy began to shine when the universe was just 150–300 million years old. The work suggests that such galaxies were responsible for dispersing the atomic fog that once cloaked the cosmos, during a period in the history of the universe that astronomers know very little about.
Following the Big Bang, 13.7 billion years ago, the universe was hot and ionized. But as the universe expanded, it cooled, and 380,000 years after the Big Bang, protons joined electrons to make neutral hydrogen atoms, which block light. Then, stars and galaxies eventually arose whose radiation ionized the universe anew, allowing light to speed through space unimpeded – a time called the epoch of reionization.
Our understanding of this ancient era is very limited because the light from galaxies that were around at the time has travelled great distances and is therefore extremely faint when it reaches Earth. As a result the study of such galaxies can only offer tantalizing clues to what happened in the early universe. But now Johan Richard of the University of Lyon in France and his colleagues have spotted a distant galaxy that appears much brighter. "What makes this object very special is that we can really get a very strong signal on a very faint object," says Richard.

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NASA'S Chandra Finds Superfluid in Neutron Star's Core

NASA's Chandra X-ray Observatory has discovered the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the core of a neutron star. Superfluids created in laboratories on Earth exhibit remarkable properties, such as the ability to climb upward and escape airtight containers. The finding has important implications for understanding nuclear interactions in matter at the highest known densities.

Neutron stars contain the densest known matter that is directly observable. One teaspoon of neutron star material weighs six billion tons. The pressure in the star's core is so high that most of the charged particles, electrons and protons, merge resulting in a star composed mostly of uncharged particles called neutrons.

Two independent research teams studied the supernova remnant Cassiopeia A, or Cas A for short, the remains of a massive star 11,000 light years away that would have appeared to explode about 330 years ago as observed from Earth. Chandra data found a rapid decline in the temperature of the ultra-dense neutron star that remained after the supernova, showing that it had cooled by about four percent over a 10-year period.

"This drop in temperature, although it sounds small, was really dramatic and surprising to see," said Dany Page of the National Autonomous University in Mexico, leader of a team with a paper published in the February 25, 2011 issue of the journal Physical Review Letters. "This means that something unusual is happening within this neutron star."

Superfluids containing charged particles are also superconductors, meaning they act as perfect electrical conductors and never lose energy. The new results strongly suggest that the remaining protons in the star's core are in a superfluid state and, because they carry a charge, also form a superconductor.

"The rapid cooling in Cas A's neutron star, seen with Chandra, is the first direct evidence that the cores of these neutron stars are, in fact, made of superfluid and superconducting material," said Peter Shternin of the Ioffe Institute in St Petersburg, Russia, leader of a team with a paper accepted in the journal Monthly Notices of the Royal Astronomical Society.

Both teams show that this rapid cooling is explained by the formation of a neutron superfluid in the core of the neutron star within about the last 100 years as seen from Earth. The rapid cooling is expected to continue for a few decades and then it should slow down.

"It turns out that Cas A may be a gift from the Universe because we would have to catch a very young neutron star at just the right point in time," said Page's co-author Madappa Prakash, from Ohio University. "Sometimes a little good fortune can go a long way in science."

The onset of superfluidity in materials on Earth occurs at extremely low temperatures near absolute zero, but in neutron stars, it can occur at temperatures near a billion degrees Celsius. Until now there was a very large uncertainty in estimates of this critical temperature. This new research constrains the critical temperature to between one half a billion to just under a billion degrees.

Cas A will allow researchers to test models of how the strong nuclear force, which binds subatomic particles, behaves in ultradense matter. These results are also important for understanding a range of behavior in neutron stars, including "glitches," neutron star precession and pulsation, magnetar outbursts and the evolution of neutron star magnetic fields.

Small sudden changes in the spin rate of rotating neutron stars, called glitches, have previously given evidence for superfluid neutrons in the crust of a neutron star, where densities are much lower than seen in the core of the star. This latest news from Cas A unveils new information about the ultra-dense inner region of the neutron star.

"Previously we had no idea how extended superconductivity of protons was in a neutron star," said Shternin's co-author Dmitry Yakovlev, also from the Ioffe Institute.

The cooling in the Cas A neutron star was first discovered by co-author Craig Heinke, from the University of Alberta, Canada, and Wynn Ho from the University of Southampton, UK, in 2010. It was the first time that astronomers have measured the rate of cooling of a young neutron star.