Tag: water

This Tiny Sponge is Probably Set to Change The World

By Anupum Pant

Background

Things absorbing water from the air is nothing new. Hygroscopic substances – or substances which have ability to attract and hold water molecules from the surrounding environment – have always been around. Coffee powder for instance is one great example – leave the dry coffee powder in the open and it will turn into a mushy matter within hours. Thanks to the moisture present in the air that it absorbs.

Hygroscopy in Nature

In the nature too, hygroscopy – the ability to extract water from thin air – has some peculiar functions. One fantastic example is the seed of the needle-and-Thread grass. This seed, with the help of a hygroscopic awn attached to it, can twist and untwist the screw like structure by releasing and absorbing moisture from the air. This way, it is able to dig its way into the ground. But that’s just one of the many examples of how hygroscopy is all around us. Here’s another one…

Thorny devil – an Australian lizard – lives in the arid scrubland and desert that covers most of central Australia. It has a hard time finding water in this dry place. So, blessed by the evolutionary forces of nature, the lizard has developed tiny hygroscopic channels between the spines on its back. These channels, working in tandem with a capillary action mechanism, are able to draw water from the air. Then their precise design makes the water move into the mouth of the lizard. Fascinating!

Other Ways

Although not exactly using hygroscopy, the Namib desert beetle, also does something similar – drawing water from thin air. Unlike the hygroscopic grooves of the thorny devil’s back, the desert dwelling beetle has developed some patterns on its hard wings which help it in drawing water from the air. These patterns include an array of  hydrophobic and hydrophilic materials which are able to trap water from the foggy morning air and are able to channel it to the beetle’s mouth.

The Nanotube Sponge Mat

This particular beetle’s hard wings with magical patterns on it, intrigued a couple of researchers. They took cue from this natural material and were able to create an artificial mat which could absorb water from the air.

nanotube sponge

Although we do have commercial Atmospheric Water Generators (AWG) which can harvest water from the air and supply drinking water, the sad thing is that these things run on electricity. This new mat that was fabricated recently, using an array of carbon nano tubes sandwiched between hydrophilic and hydrophobic layers, doesn’t need any electricity to extract water.

This mat they’ve fabricated is smaller than your thumbnail, but it still works, and is able to extract about 1/4th of it’s weigh in water within a few hours. The researchers are working on it to make it more efficient. [more information] [Original Paper]

A couple of years back a US based startup, NBD Nano, was inclined on developing a water bottle based on the same Namib desert beetle principle. The much touted water bottle, they said, would be able to fill itself! I’m not sure where their project is headed today, but an auto-filling water bottle sure would be a product just too cool to not own by every kid at school!

Needless to say, it would probably make a huge difference by lowering greatly the number of people who don’t find clean drinking water every day – Just for the record, about 1/7th of the world population didn’t have access to clean water today.

The Hard Boiled Egg Sprinkler Mystery

By Anupum Pant

Background

Cracking an egg to check if it is boiled or not is not a very intelligent way. While many know that spinning an egg can be used to determine whether an egg is a boiled one or not, I’m amazed by the sheer number of people who aren’t still aware of this trick.

Just in case you are one of those who don’t know this, it works like this –  try spinning an egg on a smooth surface. If it spins well and stands up vertically, it is a boiled egg. If it doesn’t spin properly, you can say that it isn’t cooked….as simple as that.

Tip: There’s a way to check if your eggs have gone bad without risking opening it up to take in the nasty stench. [Here]

Boiled Egg Sprinkler Experiment

Now that I’m sure you know about the boiled egg spinning trick I can tell you about this simple experiment you can do at home. Besides dealing with an angry mom, it carries no other risks.

Here’s what you do – Get some milk and pour it on the kitchen counter. Now, boil an egg if you don’t have a boiled one already. Make sure it is hard-boiled by doing the spinning test. Next, spin it on the milk puddle you created on the counter. Nasty mess ensues…

Yes, there sure is a mess afterwards. But something amazing happens when the egg spins on the milk puddle. When it spins, the egg first stands up and then the milk starts rising on the surface of the egg till it reaches the equator and then the milk gets sprinkled at the equator in a very beautiful manner. It’s like a skirt of milk. Different sprinkling effects can be obtained with different spinning speeds.

Until now, no one knew why this happened. The rotating egg would suck up milk like magic and create a fountain of milk. The exact physics part of it wasn’t known until some researchers at Brigham Young University decided to figure out why this happens. I, on the other hand didn’t even know this sprinkling thing could be done. Nice to know.

Turns out, there’s nothing peculiar about milk and eggs that creates this effect. The same thing can be done with an 8-ball or any other ball for that matter. On the other side, it works with other liquids too. For instance, if you use a liquid with a higher viscosity (glycerine and water mix), the rotating ball could create not just sprinkles, but whole sheets of liquid getting flicked off at the equator. Some times if the fluid is viscous enough and the ball is spinning fast enough, sheets spanning several feet can be seen getting flicked off the equator of the spinning balls! It’s like a motor.

Here is an amazing hi-speed video of this happening in the laboratory and the elegant physics behind has been explained too. Watch it here:

After having watched the explanation, I can say one thing for sure: There’d be no sprinkling if this was done on Superfluid Helium because superfluid helium would have no viscosity and it wouldn’t rotate with the ball!

A Book That Filters 4 Years of Drinkable Water

By Anupum Pant

I’ve written a lot about water in the past. No wonder drinking water is such a precious commodity. Still, not many have access to clean water. About a 7th of the whole world’s population don’t have clean water to drink. Every year about 3.4 Million people die out of water borne diseases.

A group of people who go by the name WaterisLife are putting in everything to change that. By working with a group of scientists from Carnegie Mellon and the University of Virginia, they have been able to come up with a novel idea that could change this. They call it the drinkable book. 

Drinkable book is a book full of cards that have been coated with silver nanoparticles. These cards bear the ability to filter dirty water and reduce the count of bacteria in it by about 99.9%. It can kill the bacteria that causes diseases like cholera, typhoid and E. coli., producing drinkable water that is as pure as tap water used in the US. Each page of this book can filter about 30 days of drinkable water. In fact, each page contains the instructions to filter water properly too. The whole book can provide 4 years of potable water. Definitely a boon to the developing countries.

The Evil Powdered Alcohol or Palcohol

By Anupum Pant

As if liquid alcohol wasn’t itself causing enough menace, now we have this futuristic powdered alcohol. They call it “Palcohol”.

All you need is, to mix a little of it with water, and there, you have your doze for the day. Other way to consume it would be to snort it for an “instantaneous high”, which by the way, is nothing less than deadly.

On an unrelated note, I find the host of this show is so adorable.

Problems

  • Palcohol certainly makes it easy for kids (and others) to carry alcohol around, and also to move it into places where it isn’t allowed (football games and concerts), which is definitely not desirable.
  • Also, the powder is highly flammable. Who wants a bomb in their pocket?
  • Another really bad thing about it is that it can easily kill you. Snorting can damage your mucous membrane. Also, since it is alcohol in high concentration, you can easily overdose on powdered alcohol and pass out.
  • The nightmare of every person, date rape, well, that just got a lot easier. Scary! How easy would it be for a creep to slip this powder into a drink of an unsuspecting victim – This is also Lacy’s primary concern (watch the video below).
  • So many new laws need to be in place before it gets available for public.

The patent to create powdered alcohol was published long back, in the 70s, but it is only now that they have got a federal approval. However, the Fed’s approval was taken back due to some issues. It is interesting to note that several other countries like Japan, Netherlands and Germany already have such products that are being sold in the market. How do the authorities in those countries  deal with this menace!

Nevertheless, Palcohol, a new and improved way to get drunk is here. It’s not going back.

Good news (?) is that it can be made at home. Read this PopSci article for the recipe.

I see only problems with Palcohol. I don’t think it needs to be in the retail market. What do you say?

Scientific Ways to Make Cut Flowers Last Longer

By Anupum Pant

Suppose, someone gives you a beautiful bouquet, celebrating a very important day of your’s, say your 50th wedding anniversary – A rare event these days. Wouldn’t it make you happier if these precious flowers last longer, even if it is just “slightly longer”? If you are a person like me who is easily moved, seeing flowers last longer would certainly make you happier!

Here are a few simple scientifically proven ways you could try that would make your cut flowers last slightly longer.

Sprite or 7-Up

Well, to make a flower last for about 3 days,  of course you could cut off an inch of the stem, clean it and put it in plain water. But there is also a little addition you can do to the water to keep them blooming for a few more days.

Add some amount of sprite or 7-Up to the water. Yes, that’s it. I know, some would consider it an urban legend or a forwarded email story, trust me, it actually works. Continue reading Scientific Ways to Make Cut Flowers Last Longer

Water vs. Red-Hot Nickel Ball

By Anupum Pant

Let me just not say anything before I make you watch this video today:

In the video, a Nickel ball is heated using a torch and is dropped into a bowl of water. As the hot ball touches water for the first time, it makes a certain “Ping” sound. It enters the water and gets covered in a bubble sort of thing. As it cools and the bubble is lost, that “ping” sound comes back again. The “Ping” repeats several times and is fun to hear a metal ball do that!

So much fun that the good guys on Reddit even made a couple of ringtones out of it. Download the longer one here. And the shorter one for notifications here.

Why does it form a Bubble cover?

This happens because the metal that is dropped into water is extremely hot and makes the water around it vaporize. The vapor formed around the ball acts as an insulator and doesn’t let the water touch the metal ball. This is the same effect that lets dip your hand in molten lead or Liquid Nitrogen without getting harmed by it. The same thing happens when you drop water on a hot pan – it dances.

This effect is called the Leidenfrost effect and I’ve covered it in an article before…

I’m not sure what exactly causes the “Ping” sound. If you know or have any theories, please tell me in the comments below.

CrashCourse in Quenching

Well, if I’d have wished to piss you off with jargon, I’d have said: “You just watched a hot Nickel ball being quenched in water”

Yes, quenching. Quenching is the name for making a hot metal cool very quickly. It is pretty interesting to know why some one would, with great effort, heat a metal, and then choose to drop it in water to cool off!
Cooling a hot piece of metal very quickly makes it extremely hard. So hard, that the same process is used to make the hard edges of swords that don’t get damaged even if they are used to cut metal!

There is so much more I wanted to write about the process, but I feel this isn’t the right place for it. Let me leave it for some other day.

No One Knows Where This Water Goes

By Anupum Pant

Background

In the Judge Magney State Park, Minnesota, as the Brule river makes it way towards Lake Superior, something very unusual happens at the Devil’s Kettle Falls – The river splits into two streams, one of which moves away like a normal stream and joins the Lake Superior. But the other stream falls down several meters into a big dark hole. No one till date, has been able to find where the water falling into this hole ends up.

Although no one has been able to prove it, the current theory which holds to some extent, says that the water flows through underground passageways and makes its way to the Lake Superior.

What all has been tried?

  • Several gallons of dye to track the water stream has been poured into the hole. The dye once poured in has been never seen again.  Besides that, so many kinds of objects have been thrown in there. Nothing ever comes out. Moreover, with every tourist, geologist or scientist throwing something in there, it has still not got clogged yet. So, it is the best place to get free ping-pong balls and other objects.
  • Some say that a car fell into the hole once and was never seen again. But those are probably just stories because the place isn’t big enough to accommodate a car.
  • Throwing in GPS tracking devices also don’t work because the stream takes them underground where they can’t be tracked by the satellites.
  • People can’t be dropped in because it is 240 meters deep and no one knows how far it keeps going. There is a lot of uncertainty to risk a human life.
  • Water-proof cameras can’t be tied to ropes and sent down because the impacts break them. Moreover, the video stream would be impossible to receive if it goes too far and several rock layers come in between.

More Mystery

But there is more. Unlike other parts of the world, where underground rivers are formed cutting through soft-rock deposits (e.g: limestone) underground, this part of Minnesota has no soft-rocks underground. So, even large underground caves can’t be used to explain the Devil’s Kettle.

Scientists have even dismissed a theory that says probably lava tubes have been formed inside. Geologists say that the kind of rock that is there inside, can’t form lava tubes.

What do you think is down there? Do you have any ideas to help figure it out?

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Snow Does Not Melt Like You Think It Would

By Anupum Pant

Background

For the last several days, the national average temperature in the US plunged by a several notches when the country was invaded by the bitingly cold polar vortex winds from the arctic, not once, twice. For the second time, the eastern sea board experienced a lot of trouble. So much that the state of Georgia, Alabama, Mississippi, Louisiana, North Carolina and South Carolina declared a state of emergency. People got trapped for hours, hundreds of accidents were reported and schools had to shut down.

Conspiracy theories

Of course with the extremely cold winds came an abnormal amount of snow. And like always, even the seemingly harmless snow spurred a few theorists to spin out conspiracy theories. There were stories going viral that suggested that the crazy amounts of snow was actually “geo-engineered” and was being sent down by the government, stuffed with nano-bots to control the minds of people.

What backed them? The theories were backed with a claim that the material falling down from the sky was not actually snow and something else which did not melt when held against a flame. Videos showing people trying to melt the snowballs using a cigarette lighter went viral. In fact, the snow as it’d be expected to, wasn’t melting, it was collapsing. Like a Styrofoam dipped in acetone, or Styrofoam held against a flame would do, snow was mysteriously disappearing from around the flame. There was no dripping water. Moreover, the concave part of the snow was left with a black charred mark like plastic would!

Busted!

Turns out the “mysterious material” was nothing more than normal snow. The lesser known fact that snow does not melt like we’d  expect it to, made people believe in the weird theories.

Yes, snow does not melt like normal ice. I mean it does melt, but it leaves almost no dripping water when the rate of melting is slow. Now, why is that?

Since, snow is porous, it contains several little holes that can suck in the water just like a tissue paper with tiny holes is able to soak in water. This particular process soaking, where tiny solid holes suck liquid, is termed as capillary action and is the same action which enables plants to suck in water from the ground and send it to the higher parts without any motor attached.

The soaking in a snowball happens in real-time. As the water gets melted, it gets soaked instantly, there is no time for the water to drip. This explains the collapsing snow.

The “charred snow” is due to the unburnt carbon left from the fuel of the lighter, not because it is made of plastic. Astronomer and science writer Phil Plait explains it in the video below. [Video]

via [PopSci]

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The Underwater Optical Man-hole

By Anupum Pant

Agreed, sometimes, when you find yourself being interrogated in a room covered with one-way mirrors, you can’t see the people who are observing you; Instead, you see yourself in the mirrors. Otherwise, If you can see something, it seems normal to assume that the thing can see you too.

A trout’s window to the outside world is something similar to what a person in the interrogation room experiences. However, unlike the person, a fish can actually see things that are out of the water, but the view is very limited.

The Snell’s Window

When a fish looks up from water, it sees only a circular window of light, from under the water surface. Everything that lies outside of this circle is darker. This darker area of vision is replaced by the reflection of the sea/lake bed (where there is no source of light to illuminate it). This effect isn’t due to any limitations of a fish’s eye. In fact, even human divers see only a circle of light when they are under water. This circle is called the Snell’s Window or the optical man-hole.

Irrespective of the fish’s visual acuity, some physical properties of water and air get together and have a great effects on what a fish can see. It sees a circle with diameter calculated by the Snell’s equation.
In short, the window is about 2.3 times as wide as the fish’s depth. So, a fish can see more if it goes deeper. At a depth of 1 meter, it can clearly see things on a circle that is 2.3 m wide on the surface of water.

So, even if you can see a fish in water, it will be foolish to assume that the fish can see you too. Some times it can’t. It looks something like this from under water:

In Wikipedia’s words:

Snell’s window is a phenomenon by which an underwater viewer sees everything above the surface through a cone of light of width of about 96 degrees.

Why does it happen?

It happens due to a simple optical phenomenon called the total internal reflection.
The physics behind this phenomenon can be read here. [Read here]

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Making Fresh Water With Apple and Tomato Peels

By Anupum Pant

Water on Earth

It’s Christmas! On this happy day let’s take a minute to look at what the major part of the world is facing today.

The present situation might not look as bad, but the truth is that we are running out of fresh water. To give you an idea about how much water is actually there on earth, this image of the whole world’s water compared with the size of earth is, in my view, the best thing that could prove it to you.

Fresh water in all the lakes and rivers on the whole planet is represented by the tiniest dot.  Yes, there is a third water sphere in the picture. You might have to squint to find it. So, that is the amount of fresh water we have here on earth.

global-water-volume-fresh
Source: http://ga.water.usgs.gov/edu/earthhowmuch.html

War for water: If this image isn’t much of a proof that fresh water is scarce, probably this will do the trick:
Countries consider fresh water a very precious resource. Several countries all around the world are fighting with their neighbors for this blue gold. Two good examples of that – [India starts water war] and [This]

The Point

Today, economically and technologically backward countries require good cost-effective methods to purify water. Scientists are doing a tremendous amount of work in this area and coming out with innovative methods to deal with the problem. Also, it is one great idea for taking up as a science fair project by students. One such recent research regarding this caught my attention.

The fruit peel method

Note: If you are wondering why have I written fruit when we are dealing with a tomato here, this might come as a shock to you that Tomato is actually a fruit. And BTW:

Knowledge is knowing that a tomato is a fruit. Wisdom is knowing that a tomato doesn’t belong in a fruit salad. – Miles Kingston

Mr Ramakrishna Mallampati, under the guidance of Associate Professor Suresh Valiyaveettil of the Department of Chemistry at the NUS Faculty of Science, have discovered a new way of purifying water which is both innovative and cost effective. Moreover, it uses the waste product of a fruit, its peel, for something good. They hope that their new technology will comes as a boon to the people living in areas where a water treatment plant cannot be set up.

According to their research, a tomato’s peel, under certain conditions, can remove dissolved organic and inorganic chemicals, dyes and pesticides. Additionally, an apple’s peel was also found to have these wonderful properties. Apple’s peel loaded with Zirconium were found to be effective in removing phosphate, arsenate, arsenite, and chromate anions. This is the first time ever someone has used to remove two different kinds of pollutants using two different kinds of peels. Notably, all their processes can be scaled up for large scale applications.

I hope that this new discovery will come as a respite to all the poor nations where people die everyday due to the unavailability of drinking water – due to diseases.

Source: http://water.org/water-crisis/water-facts/water/#
Source: http://water.org/water-crisis/water-facts/water/#

For more details – [NUS researchers developed world’s first water treatment techniques using apple and tomato peels]

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Mpemba Effect – Hot Water Freezes Faster Than Cold Water

By Anupum Pant

In the past, we have seen that when it comes to estimating temperature, we are not so smart. Once again seeing the Mpemba Effect defying all known logic, reminds me to be careful about applying logic to most of the natural phenomena which are seemingly simple but in reality are extremely complicated.

By applying simple logic, a 7-year-old could tell you that cold water should turn into ice quicker than hot water would. It should, because a hot liquid contains a lot more heat as compared to a colder liquid, which [the heat]  has to be removed in order to freeze it. Yes, it is what anyone who is unaware of the Mpemba Effect would think. But, that isn’t the case with water. It turns out that a very common substance – water – is not as simple as it looks.

Mpemba Effect

Since the time of Aristotle and Descartes, scientists have noted that hot water can freeze faster than cold water (and yet the effect is not popularly known among us today). Although the effect was noted back then, the actual mechanism which caused it remained a mystery all along…until the year 2013.

All this time this effect must have been known by some other term because, it was not until the 1960s it was named “Mpemba effect”. It was named that after a Tanzanian cookery student Erasto Mpemba when he observed that hot ice cream mix froze faster than the cold mix.

Several theories have tried to explain the mechanisms that cause the Mpemba Effect. Not even one of them was convincing enough. Probably this is what propelled the geniuses from Singapore who could finally solve this mystery during the month of October this year.

What causes it?

In simple words, Hydrogen bonds cause this effect – faster freezing hot water. Normally, individual water molecules are connected by this bond called the Hydrogen bond. Think of the water molecule as a string with two bullies – hydrogen bonds – one on either side. These Hydrogen bonds pull this string from both sides. As a result, the string stretches. We’ve all fought with rubber bands and know that a stretched string has a butt load of energy stored inside it. The same thing happens with water. Energy is stored in stretched water molecules at normal temperature. This extra energy has to be removed to cool water.

At a higher temperature, the heat kind of weakens these bullies. So, the weak bullies aren’t able to pull the string as much. Now, individual molecules sit apart. They are no longer stretched. Thus, not much energy is stored in these strings anymore. They have given up energy. There is no longer any extra energy that needs to be removed. Hence, cooling is faster.

Sorry: Today I don’t have my buddy – the internet – with me. So, you won’t see any outgoing reference links today. I have a just a bit of internet (a slower 2G connection) which I’m using up to publish this.

Building A Solar Death Ray At Home

By Anupum Pant

Sun’s Energy

Sun is an huge fusion reactor. Every second it produces enough energy that could power the US for 9 million years. But from the perspective of people living on earth, most of it radiates into the space and gets ‘wasted’. Still by using even the part of energy that is received by us, a solar death ray that melts steel can be built.

Earth is only a fraction of the size of sun. In comparison, sun is so mind-boggling-ly big that I bet you can’t manually scroll this page from Sun, all the way to earth (and this is a heavily scaled down version of our Solar System). In short, earth is so small that it receives a microscopic fraction of the energy radiated out by the sun.

Technically: The total flux received by earth is about 343 Watt per meter squared. On the way to earth’s surface, 30% of this gets scattered by the atmosphere and 19% of it is absorbed by the clouds. So, out of 343, only 51 percent reaches the surface. Which is calculated to be about 175 Watt per meter squared. Which is a very small part of the energy that sun gives out. [Source]

And yet, sunlight received by earth has by far has the highest theoretical potential of the earth’s renewable energy sources.

Harnessing this energy

For humans, it is possible to directly harness this energy broadly in two ways – heat or electricity (photoelectric effect). We are interested in only the heat part here. To demonstrate the kind of heat that can be generated by focusing 2 meter square worth of this energy to a single point, watch how this equipment can melt steel in seconds (The melting point of steel is around 1500 degree centigrade).

Making at home

Building something similar at home is fairly easy as far as the concept is concerned. But the process can be very tedious. I found three interesting ways in which this can be done at home.

1. Using a satellite dish: A satellite dish is parabolic and is designed to focus signal to a single point. Instead of signal, you could use it to focus light (sun rays). To use an old dish for making a solar death ray, all you’ll have to do is stick 5,800 tiny pieces of mirrors on its surface, like Eric Jacqmain did. – [Source]

2. Use a projection TV: A projection TV has a huge Fresnel lens in front of it. It is kind of a convex lens that is flat. If you can find an old projection TV, you could use the screen to make a solar death ray like Grant Thompson did.

3. Using water: Another creative way could be to use water. By combining the power of gravity and stretching plastic, you could turn clear water into a parabolic lens like this [Video]. Although I don’t think something like this could be efficient enough to melt steel. It could still be used as an outdoor machine to cook breakfast.

EDIT: Why isn’t there a comments section?

First I forgot to add this and remembered only when a reader pointed it out. I promised in my yesterday’s post, that i’d tell you the reason behind a missing comments section on this blog. Here it goes…

I use a theme built by Leo Babauta (see FAQ) and am a fan of his teachings. It [the theme] has an inbuilt comment section but Leo doesn’t use comments on his blog. For me to not use it too, there are 3 reasons:

  1. I’m a fan of Leo Babauta and try to emulate his ways in my life. (not perfectly)
  2. I want to create a pure reading experience for the reader (now ads, which hinder the pure reading experience, are for experiment only). People who really like to interact usually mail me. And it is a much more enriching experience.
  3. Unlike every other blogger, comments have a great effect on me. This in turn affects my ability to write. For instance, comments which appreciate, seem flattering to me. As a result, I become complacent. If they are critical, I get concerned about my writing abilities. There are hardly any neutral comments. I’d like to focus my energy on writing than arguing on the internet.

I do have plans to include it in the future. It is just that I’m not sure when I’ll do it. Probably when I change my theme, I’ll do that.

Dancing Drops of Water and Dipping Hands in Molten Metal

By Anupum Pant

When you sprinkle water on a hot pan, you’ll find that the droplets start dancing on the surface, as if there was no friction at all. From far, this effect looks a lot like water droplets on a lotus leaf (a super-hydrophobic surface). But, the physics behind this phenomenon is completely different. Read on to find out what is the mystery behind these dancing drops of water.

The Leidenfrost Effect

Why does this happen?
Unlike the drops on a lotus leaf, this happens at a particular temperature for a specific liquid. Different kinds of liquids display this effect at different temperatures.
For water, at a temperature when a small amount of water in contact with the pan gets heated enough to form a thin-film of vapor below the drop, water is no longer stuck on the pan (water sticks to some surfaces due to low surface tension). The drop has a thin vapor film below it which enables the drop to move around on the film. The formation of this vapor film is a continuous process, till the whole drop turns into water, one film at a time. This is called the Leidenfrost Effect.

Some liquids like liquid Nitrogen are extremely cold. At normal room temperature, they start boiling. A normal room’s floor is like a hot pan for liquid Nitrogen. So, it forms these dancing drops on a floor which is just at room temperature. You can try this yourself – If you can find some liquid Nitrogen, you can simply drop it on the floor and watch droplets moving effortlessly. They won’t stop moving!

Dipping hands in Liquid Nitrogen

The temperature of liquid Nitrogen is around -195 degree centigrade. It is one of the coldest substances and is used with extreme caution in industries and laboratories. If it touches you, your skin can easily get burnt. Yes, burnt – at extremely low temperature. It could probably also make the dipped limb useless for life. So, you shouldn’t try stuff with liquid Nitrogen at home.

But, it turns out, you can safely dip your hand in it for a small amount of time and return unharmed. Thanks to the Leidenfrost effect. Our hot-pan like hand – for cold liquid Nitrogen – makes a thin film of vaporized Nitrogen around the whole hand. This film, protects our skin from the ill effects of extremely cold temperatures. Still, there is no reason for you to try this. It has been done already.

The crazy duo from Myth Busters tried this with molten lead. It worked!  They, of course had to wet the finger with water – for the vapor film formation.

Water flowing uphill

Recently, an undergraduate research student group from the University of Bath found out a way to manipulate the movement of water on a specially designed surface, using this phenomenon. They found that machining ridges on the surface (and heating it) would make the thin vapor films under water droplets move in such a way, that they could use it to propel drops against gravity. They were able to demonstrate this by showing water moving uphill on a slope. It is enthralling to see it for yourself. I’ve attached their video below.

Hot Ice

By Anupum Pant

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For years we’ve been subconsciously conditioned to think of something cool when the word ‘ice’ is heard. But, does ice always has to be cool? How much more interesting, than water-ice, can ice be?

What is it?

The name: Hot ice isn’t solidified water, it isn’t anything even close to water. Neither is hot ice, hot. It is just a common name for Sodium Acetate Trihydrate. At room temperature, this substance looks like ice crystals and if heated, it starts turning into a transparent liquid. Since, the ice like crystals are formed at a relatively hotter temperature than water-ice, it is called hot ice.

Everything freezes. While metals ‘freeze’ at extremely high temperatures and carbon dioxide freezes at extremely low temperature, Sodium acetate freezes at 54 degrees centigrade. But, that is hardly anything interesting about it. There is more.

Touch water and turn it to ice

Think about water: Cooling water, beyond its freezing point without it getting solidified, can be done and it is called ‘super-cooling‘. This can be done by not letting water (distilled water) find any ‘nucleation points’ or simply by using an extremely clean tray to freeze it. Now, water remains in a liquid state despite being cooled under 0 degree centigrade. At such a state, if water is disturbed, say using your finger, a chain reaction starts and the water freezes almost instantly. But, doing it is tough.

Making hot ice at home – The same thing that happens with super-cooled water, can happen with sodium acetate. Touch the liquid sodium acetate and it magically turns to ice, it is indeed a fascinating process to watch (watch in the video below). And can be done fairly easily. Moreover, you are not at a danger of getting poisoned in any way. This is the reason it is used to make hot ice. It can be made at home using vinegar, baking soda and a steel vessel.

Super-hydrophobic Surfaces are Unbelievable

by Anupum Pant

It is almost impossible to get a lotus leaf wet. If you try pouring water on it, you’ll see that it will form little beads of water and quickly roll out of the leaf. This happens because a lotus leaf is super-hydrophobic. Although, even your raincoat doesn’t get wet, it isn’t super-hydrophobic. Water sticks to on the surface of a raincoat. Super-hydrophobic surfaces don’t let water stick on it. But how do they manage to do that?

The science – Contact angle

Every time a liquid sits on the surface of a solid, the liquid drop forms an angle of contact as shown below. Things that don’t get wet have a contact angle greater than 90 degrees and the ones that get wet form an angle lesser than 90 degrees. The greatest angle is always less than 180 degrees. Theoretically, a perfect bead will form at that angle.

Super-hydrophobic surfaces are able to push this angle to as high as 175 degrees to form almost a perfectly spherical water droplet on the surface (due to very high surface energy). This ensures that as soon as water falls on it, it rolls away. The surface never gets wet.

Advantages

Imagine things never getting wet. How about a completely water resistant phone, a shoe that never gets dirty, shirts that repel ice-cream and wind-screens rolling away rain droplets like magic? All these things are possible, if they can be converted into super-hydrophobic surfaces. [They can be. Watch the video below]

Besides repelling water, these surfaces can also prevent formation of ice, resist corrosion and prevent bacteria from sticking to it. The possibilities are endless.

How to do it artificially?

Today, we have managed to develop several artificial methods to make almost any surface super-hydrophobic. Commercial services like NeverWet, HydroBead and Lotus leaf coatings are making a roar in the market by offering amazing promises. Normally, they use simplified spray coatings to convert normal surfaces to super-hydrophobic surfaces, so any one can use them, anywhere.