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.

Things You Should Know About Farts

by Anupum Pant

Flatulence, an expulsion of intestinal gas, commonly known as fart, is something no one likes to talk about because it is considered a taboo, almost everywhere in the world. To top it all, some might even sideline this article by tagging it as a vulgar one. In my defense, that is exactly the purpose of my blog – To talk about things no one will talk to you at school (or anywhere else). Our inclination here is to learn.

Avoid shaming others for it.
Firstly, it is important to know that, irrespective or gender, race or nationality, farting is an invariable result of digestion and everyone does it about ten times a day. Even dead people fart. So, by shaming someone for letting it out in an accidentally loud way, is hypocritical on your part; it [shaming others] can be avoided. As Eric Auld says, it is okay to fart.

Do not hold it.
Secondly, it is not okay to hold flatulence to avoid embarrassment. Doing this, has the potential to cause a life threatening condition called diverticulitis. This disease is prevalent among the urban people for obvious reasons. Urban people have a greater societal pressure to hold it, than a free-living farmer. To give you an idea, 30 million Americans are currently suffering from it (old data).

What is it?

Principally, it is a mixture of gases taken in through mouth with food and gases which are produced while digesting food. The composition of ‘gas’ varies with, people, the kind of bacteria in their stomach and the kinds of food they eat. Oftentimes, people don’t hate their own smell; at the same time, detest the gases coming out from others. A fart is comprised of gases like Hydrogen, Nitrogen, Carbon dioxide, Oxygen and Methane. It smells bad due to the presence of Hydrogen Sulfide, Mercaptans and Ammonia. And the presence of inflammable gases like Hydrogen and Methane makes them inflammable.

Farts in a humid environment can seem worse because during such conditions, our sense of smell is enhanced. This is the reason why farts smell worse in a shower.

Minimizing the effect

Although, there is no way you can end this trouble from your life, you can adjust your diet a bit to prevent this from happening in excess. Beans, cauliflower, corn, eggs etc are some foods which are notorious for producing gas in your body. These foods release a relatively greater amount of gas than other foods while getting digested in the intestines. Cutting their intake can help (of course consult your doctor first).

Another way to lower the problem is to prevent the odor from troubling others. This can be done by using products like “odor-proof undies”.

Coughing or suddenly moving your chair could help you to mask the sound.

 

A Bat’s Inverted Sleep Position

by Anupum Pant

I have written about sloths in the past. In that post, we appreciated the way their bodies are engineered to stay inverted for most of their lives. It turns out, a bat’s body is designed (rather evolved) in a similar way, which enables them to relax and sleep upside down. In this post, I would like to discuss – why did they evolve this way and how do they do it?

If you are interested to know more about bats, you will definitely like this post from the archives. [Bats can See]

How can bats manage to sleep like this?

Humans sleep in a horizontal position, cows sleep with their eyes open, horses sleep in a standing position, and of course, bats sleep in an inverted position. What makes an animal sleep in the position they do, is basically their anatomy – the way their bodies are designed. While sleeping upside down might seem as an anomalous behavior to us, it is a normal position for the bat’s body. Like we don’t exert energy when we are lying down, bats’ bodies don’t consume extra energy for hanging down like that.

Firstly, a bat’s claw is like a hook. A better way to understand why this helps is, to look at a converse behavior – the way a human hand works. We use up energy to contract tens of muscles and make up a hook with our fingers; this is not a normal state of our hand. Also, our relaxed hands are open where we don’t exert any energy and we sleep with our hands in that position. A bat’s claws are designed in a completely inverse fashion; they are hooked in the normal position. They don’t take up energy to make them into hooks, they are like that. And they sleep like that – which enables them to hang without using energy.
So, unlike our hands, a bats’ closed fist is their relaxed position. They have to contract tendons and use energy to open them up. This anomalous talon design allows them to hang in a relaxed position.

Bat's Talons - Normal position

Secondly, unlike every other bird, a bat can’t take off from an upright position, or from the ground. They have to be inverted to start flying. This is because they have relatively weaker wings which can’t make them fly from a stationary position. Think of an X-51A Waverider, which has to be carried on a B-52 plane and dropped down to start a flight. They drop down for a very small amount of time and beat their wings vigorously to start a flight. Since, they have to wake up inverted to go flying and catch a meal, they go to sleep like that.

Why did they evolve this way?

They’ve evolved this way to simply stay away from the predators:

  1. By hiding up in a place where not many predators would look – under a bridge, roof of the cave and dark tree canopies. Also, at places like these, they don’t have to compete with other birds for a place.
  2. And by escaping quickly in case of an attack by attaining instant flight [see above].