What could we learn?

One of the first things I did when I arrived in Dunedin for the first time in 2012 was to go to the Royal Albatross Centre. This place is the only mainland colony in the word where you can observe the Northern Royal Albatross in their natural habitat. Particularly impressive when they glide, the albatrosses are also interesting for their snot.

Yes, you read that correctly. The albatross’ snot could help us to imagine and develop a new desalination technique.

It is well known that drinking seawater is unhealthy. The amount of salt is so high that it will dehydrate your body. As a result you will be dehydrated pretty quickly, and if you don’t get fresh water soon enough you will get ill and even die.

Ok, but what about seabirds? Their main water resource is from seawater, and they look fine. They are fine. How so?

Researchers were curious to know how seabirds could drink seawater. They analysed their urine and only found small amount of salt. They thought maybe they are not drinking seawater! To check the hypothesis they made albatrosses drink seawater and observe that they were totally fine with it. They finally discover a HUGE amount of salt in the birds’ snots, or should I say, in the fluid coming out of their nostrils.

How do they do that? Snots glands! Nah, I’m kidding. A pair of nasal glands produce the salt solution coming out of their nostrils. In other species drinking seawater like sea turtles or iguanas, the same function is accomplished by the salt glands or supraorbital glands in penguins.

If you have a look at the picture below you can see that there is transportation of the salt (NaCl) through secretory cells from the blood to secretory tubules, which will excrete the super salty fluid by the nostril.

salt excretionCredit: Pearson Education, Inc. publishing as Benjamin Cummings

Thanks to the nasal glands, the albatross are able to drink seawater and get water out of it, where we would lose more water in the process of trying to eliminate the excess of salt!

Now, the challenge is to work out a process that could do the same with a low environmental impact and low manufacturing cost (in a perfect world I guess). And, once more, another good solution would be to consume less water ;).

Through this post, I wanted to show you that besides all the technologies already based on Nature; there is still much more to learn!

Nature is a bottomless source of inspiration. Take the time to go outside and observe the world. Get inspired and stay amazed by what Nature has to offer. None of what is around is there by mistake or by chance. Every piece of Nature is the product of millions years of Evolution. Appreciate it.

 

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I’m watching You

Last week our teacher told us the only way to get him really interested in a blog was to make it about cameras. All right, here we go. I’m quite happy to do it because it gave me the excuse to spend some time on the Internet looking at amazing macro pictures of insects’ eyes…

Sahan1 Eyes compilation (from left to right): Dragonfly, Longhorned beetle, Robber fly and Horse fly.
Credit: Thomas Shahan / Flickr

Humans’ vision is based on one lens while insects’ vision is based on multiple lenses. That’s why their eyes are called compound eyes. Their eyes are composed of lots of facets called ommatidia. From 4000 per eyes in the houseflies to 30 000 in the dragonflies! Each ommatidium has a lens collecting light. These ommatidia are placed on a convex surface; this way they all see something slightly different. The final image is not like a kaleidoscope as you may think because of some movies. What he insect actually sees is a combination of the images collected by all the ommatidia.

Insect vision Credit: ASU – Ask A Biologist

For insects with one eye on each side of their head, it brings a field of view (FOV) of 360°. They can see everything! Thanks to that they are extraordinarily efficient at detecting any movement. The Karate Kid was probably cheating.

The 360° view is something highly coveted in the photography world. But that’s about the only thing we might want from them. Besides this exceptional aptitude, the insects’ eyes are not that exciting. Because the eyes/ommatidia are so small, there is a limit to their image resolution. Moreover, the insects can’t focus like we do. The final image then depends on the number of ommatidia (more is better), and the position of the eyes on the head, so that most of them can see are shapes and that’s about it (see previous image). To have good resolution (quality of the image) comparable to ours, the insects would need ommatidia with a radius of 11 metres!

What we want here is using the 360° vision from the insects’ eyes combined with a good image resolution like the humans’ eyes. This kind of characteristics applied to a camera would increase the efficiency of security cameras (but not for privacy) and would also be extremely useful for endoscopy for example!

Different teams are actually developing this camera. Curvace from Switzerland, Ohio State University and John Roger’s team from the University of Illinois at Urbana-Champaign. They published a paper in May 2013 explaining a methodology to reach this kind of digital camera. The actual device should not take too long.

Fly_eye_camera

Credit: University of Illinois and Beckman Institute

So what’s important to remember here? Even if the insects’ eyes might seem imperfect, they have advantages linked to their way of life (avoiding your swat). While the basic structure is the same there are lots of variations in the details. An easy one: the eyes will be placed differently function of the insect status. A predatory insect will have its eyes more at the front to concentrate on its prey while a insect feeding on plants will have its eyes on each sides to be aware of its surrounding and be ready to react to any threats.

The Invisible Master

I remember receiving an email from my father a few years back. I thought it was curious since we were living in the same house… Why would he send me an email instead of talking to me?

It was worth it. No words could have done justice to the pictures of Liu Bolin the Invisible Man. I’m not usually interested in art, but these were freaking awesome! This guy is very successful in using the art of camouflage to hide in our everyday environment.

Our desire to be invisible is not new, and industry has been interested in the art and science of camouflage since the First World War. At this point camouflage became an essential part of military tactics. The objective was simple; you had to deceive the enemy. To do so, the Dazzle camouflage (ship camouflage, see picture below) appeared. The goal was to make your position unclear. This way, the enemy was not sure at what distance, how big, and how fast you were moving.

U.S. NavyArgus wearing dazzle camouflage, 1917.

Then arrived the well-known camouflage clothes. Basically, brown- and greenish colours with weird patterns. First reserved for the military they then spread into fashion (thankfully, that is over!). But don’t think the matter is over… For years scientists have been studying how to improve these camouflage fabrics. Instead of one printed pattern, what they want now is a dynamic coating that will change according to the environment. We are once again turning to nature, trying to mimic not a chameleon but an octopus!

Even if the mystery is not completely resolved yet (scientists do not always agree on everything). We have some clues about how these creatures change colours depending on their surrounding environment. Combinations of cells. The whole body of cephalopods (octopus, squid and cuttlefish) are covered by multiple layers of special light and colour-sensitive cells able to “see” the environment. All together, they allow the animal to rapidly change their colour when they need to hide.

The cephalopods live in the oceans all over the world. The ocean might be a tricky place when you want to hide from predators. Especially when you don’t have a shell to protect you! Some places look like deserts without any vegetation and barely anything but small rocks or sand. It then seems prudent to develop a technique to camouflage quickly when danger is approaching.

At least four different cells allow the octopus to be the Invisible Master. Chromatophores, leucophores, iridophores, and photophores. Depending on their habitat (oceans can be very different), the octopus will use some cells more than others.

First, the chromatophores. These cells are localised just under the skin. Each chromatophore’s cell contains pigment granules of a specific colour: Brown, red or yellow. Tiny muscles surround each cell. They control the expansion or retraction of the cell. By expanding the cell, the pigments are spreading out and the octopus’ colour will change. These chromatophores are controlled by the brain, which allows astonishingly quick colour change.

Then, the iridophores. These cells are located under the chromatophores. They are responsible for the green, blue, gold and silver colours but scientists are not entirely sure yet how they work. Some think that they reflect the wavelength thanks to proteins called reflectin. Others think that their colour is permanent and finally, some think hormones control the colour. In that last case, that would mean that every change of colour would take a long time compared to the chromatophores reactivity. The chromatophores would then be used to hide the iridophores while they are not yet of the appropriate colour. This option seems particularly complicated. That means that the chromatophores have to “know” what colour the iridophores are and what colour they have to be. The reflection hypothesis seems more probable.

Prilfish1
Cuttlefish
Credit: Prilfish / Flickr

The leucophores. These cells are located under the iridophores and change colour depending on the main wavelength present in the environment: white near the surface and blue in deeper water. The leucophores are mainly responsible for the white spots.

prilfish
Octopus
Credit: Prilfish / Flickr

And finally, the photophores. As the name implies, the photophores are cells that produce light. They are producing light through bioluminescence. That means that there is a chemical reaction occurring inside the cells and creating light, or in some species, the light can be produce by special bacteria contained inside the cells!

All together, these cells allow the cephalopods to be masters in the art of camouflage, and quicker than our master Liu Bolin.

What about us?

No invisibility cloak yet. But the combination of the reflectin proteins from the iridophores with a super-thin material called graphene could lead to coatings that make you invisible to night-vision cameras and other infrared detectors. This coating would reflect the light or NOT based on chemical signals. The researchers even think they would be able to make the coating visible or invisible by changing the humidity. This way, every night when the humidity is higher, we would switch into invisible mode!

 harry potter

 

Keeping it together

History. Another subject I’ve never been good at. I have an incredibly bad memory and learning stuff by heart has never been for me. Anyway, history is important in every matter. History helps us to understand the context in which our subject/story has evolved. So today, we will learn a bit more about the beginning of technologies inspired by Nature. By the way guys, there is an actual name to characterise my blog theme: biomimicry or biomimetic. The creation of technologies by mimicking what we learned from Nature.

After reading all those posts, did you wonder what was the most famous example of biomimicry? What about the featured image for this post? Does that help? And what about the image below?

Dan McKayCredit: Dan McKay / Flickr

Here we go! Yes, the most famous example of innovation inspired by Nature is the hook-and-loop fastener or zipperless zipper, better known under the name Velcro©.

What is the history of this awesome invention?

Have you ever gone for a walk in the woods and then realised you had lots of burrs stuck on your clothes? Those burrs (plants seeds) are so annoying right?

In the late 1940s a Swiss guy (George de Mestral) wondered why burdock burrs were sticking on his dog hair and on his clothes. He got the idea to look at one of them more closely under a microscope. Actually, you might not even need a microscope. If you look at the spikes on the very first picture, you will notice hooks at the spikes edge. Those tiny hooks allow the plants seeds to attach to animals or humans passing by.

Before going further in Velcro’s history, I guess some of you are wondering why those seeds have hooks all over themselves. The hooks have two functions. First, they are a good way to repel animals (like prickles) that would like to eat them. Secondly they allow the seeds to be dispersed away from the “parent plant”. The seeds dispersion by animals is called zoochory while the dispersion by humans is called antropochory.

Let’s go back to Velcro now. This technology is based on two parts that are attaching to each other. One side is covered by tiny hooks (mimicking the seeds) and the other side is covered by tiny loops (mimicking animal hairs or humans clothes). The image below shows a closer look to the hook part.

mikeyp2000 flickrCredit: Michael Phillips

Velcro was introduced to the world in 1948 and patented in 1955. But it’s only in the late 1950s that Velcro was commercially introduced. Ten years later, Apollo astronauts started to use Velcro in space to hold their equipment in place. But despite this big advertising, the lack of aesthetic confined the use of Velcro to NASA and sport equipment.

Then, between 1968 and the 1980s, Velcro was integrated into kids’ shoes. At the same period, the patent expired and imitators arose all over the world. Often cheaper but also of lower quality, these competitors were not good for Velcro’s industry.

In 1984 Velcro used an incredibly powerful advertisement: A man in a Velcro suit jumped off a trampoline onto a wall (have a look at the video below!). Thanks to this advertising, the use of Velcro exploded. People started to use Velcro to attach electronic devices in their car; toy companies started to use Velcro in more and more toys and in childhood education tools. Then in 1988, the manufacturing progresses led to the actual Velcro we know (in nylon and plastic).

Any bad things that happened to Velcro? In 2004 the U.S. Army decided to include Velcro on their new uniform. The goal was to make them lighter, in that they succeeded. But they also succeeded making them noisy! Which, in certain contexts could become a very important issue.

Nowadays, Velcro is used everywhere when things have to be attached and taken apart repeatedly. From kids’ shoes to astronauts’ equipment, Velcro is a fantastic tool. Again, a great technology inspired by Nature.

Stuck on you

Every Friday at lunchtime, there is a seminar in the Zoology department at Otago University. It is always interesting to go to learn new things and see what people are working on. Two weeks ago I attended the talk from Dr Elodie Urlacher about the honeybees learning ability under stress. That was fascinating. And last Friday, Dr Fanny Maure talked about a system of parasitism. Parasitism. What another great topic!

Let’s start at the beginning. What’s a parasite?

A parasite is an organism (plant, animal, virus, etc.) that lives in (endoparasite) or on (ectoparasite) another organism (called the host). The parasite benefits from the host by getting its food and/or protection and/or a site to reproduce etc. In brief, the host is utilised by the parasite and doesn’t get anything in return. During her talk, Dr Maure mentioned the extraordinary ability of some parasites to modify the behaviour of their host. The great example she used is from a shrimp (Gammarus insensibilis). When infected by a flatworm parasite (Microphallus papillorobustus), the shrimp’s behaviour is changed. It goes up to the surface of the water and is attracted to light. So what? Because of this behaviour, the shrimp is much more likely to be eaten by a bird! We can almost say that the parasite is pushing its host to commit suicide. Why is that? The shrimp is actually only an intermediate. The parasite needs another host, the bird, to accomplish its life cycle and reproduce.

   parasite life cycle

 Credit: Manon Knapen, adapted from Mouritsen et al.1997

Great but where is the technology? Be patient, it’s coming. To get to the technology, we need to switch to another parasite. Pomphorhynchus laevis. Another terrible name, I know. This parasite is a worm that looks like the one below. The trunk-like end covered with hooks is the proboscis (yes, you’ve read that term before in the mosquitoes post). The worm swells its proboscis to attach and enter into its first host. Its long ‘armored’ proboscis provides a good anchorage but that’s not all. As you can see, there is a small bulb at its base. Following the penetration in the host, the worm swells the bulb making it almost impossible to detach.

Pomphorhynchus tereticollisLarval stage of the fish parasite Pomphorhynchus tereticollis. (A) Pomphorhynchus tereticollis (B) Detail of proboscis. Scale bar = 500 µm.
Credit: Emde et al., 2012

Here we go! We have a spiny-headed worm. Its proboscis is very efficient at penetrating the skin and other tissues. But more importantly, its proboscis has a particularly good anchorage thanks to its bulb. Any idea what we could do with that?

Jeffrey Karp from the Harvard Medical School realised that the adaptable shape of the proboscis would be ideal for bandages. Don’t worry, he was not interested in the hooks covering the proboscis but in the special bulb at its base. With his team, they developed a microneedle made of two different parts: a swellable part and a non-swellable part (see figure below). The swellable part actually swells on contact with water. As you can see, the insertion of the needle is easy since it has a sharp end. Then, the swellable part of the needle reacts with the water and swells. The swellable part of the microneedle assures a good anchorage to the tissue. This new technology (still in development) could improve bandages. You are maybe wondering why on earth we would like to stab tiny needles in our skin each time we need a bandage. Those needles are actually so tiny they don’t do any damage to your skin. Moreover the good anchorage of the bandage means it would be as sturdy on your fore arm as on the back of your knee. No more loss of bandages under the shower or because you move too much. The technology is particularly exciting when it comes to developing new kinds of stitches and staples. The design also allows drugs to be included in the swellable part, which could help their application into the tissue. Finally, as it is a reversible process the microneedle can be removed easily without damaging to the tissue.

Concept of the bio-inspired microneedle adhesive
Credit: Yun Yang et al., 2013

Guess what? This parasite also influences the behaviour of its first host! Once he gets into it (another freshwater shrimp, Gammarus pulex) thanks to its super proboscis, the parasite will lead to a change of its behaviour. The shrimp will not avoid its predators anymore and its colour will change. The shrimp becomes more visible to its predators (freshwater fish). Once again the parasite induces the ‘suicide’ of its first host to get to the final host where it will be able to reproduce. Genius.

The Perfect Stone

One of my classmates is writing her blog about rocks. That made me remember the geology paper I had as an undergrad. Friends and I kept saying the word ‘stone’ instead of rocks. That made our teacher pretty upset more than once. I can still hear her saying: “Girls, those are not simple stones. They are rocks. Minerals, …”. And a few minutes after, I was back talking about ‘stone’. I have to say I have never been really interested in them. I like animals, plants, and interactions between them. I am particularly interested in their evolution to adapt to our changing world. But what do rocks do? They are just there. Static. Right?

False!

Once again I was wrong. Rocks are not that boring. They actually do stuff. Today I am going to talk about one of the things some rocks do. Well, don’t be too excited. You won’t actually see anything.

Let’s have a closer look at a specific type of rock, the peridotite. This rock is mostly made of two minerals, olivine and pyroxene. But what are minerals? Briefly: Minerals are substances naturally occurring, solid at room temperature and with an organised structure. Another characteristic of minerals is that they have a specific chemical formula (e.g.: olivine is (Mg, Fe)2SiO4) contrary to rocks. Rocks are made of those minerals and other non-minerals constituents and can’t be characterized by a specific chemical formula.

 Halite-Nahcolite
Minerals halite (pink) with nahcolite.
Credit: Jolyon Ralph/Flickr

Back to our peridotite. What’s special with this rock? Like I told you before, the peridotite is mainly composed of olivine and pyroxene. What is actually interesting is that these two minerals are reacting with CO2 from the atmosphere. Yes, you read it! There is a rock able to capture CO2 and transform this gas into stable minerals, such as calcite (yes, I already talked about calcite).

How is that possible? Chemistry!

There is a reaction between the rock’s components and the atmospheric CO2. This mineral carbonation (name of the reaction) occurs between CO2 and alkaline-earth oxides. These alkaline-earth oxides are simply the elements (metals) from the second columns of the periodic table. Beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). They are characterized by their solid state even at very high temperatures (700°C to 1290°C).

The reaction transforms the gas into minerals like magnesite and calcite.

carbonation
Equations of Carbonation reaction.
Credit: Kelemen and Matter, 2008

Prato Fundo

Periodic table made of biscuits.
Yeah, it seems much easier to learn it by eating it, don’t you think?
Credit: Prato Fundo/Flickr

Of course, that’s not all, there is also conditions of temperature and pressure needed for the carbonation to take place. But I won’t go further into those parameters today. But be aware that they are also very important for the mineral carbonation to take place.

Where can we find this precious rock?

The peridotite is the main constituent of the Earth’s upper mantle (see figure below). That means it is all but unreachable. However some is actually exposed in some locations. You can find them in Oman (Southwest Asia), Papua New Guinea, New Caledonia and along the coast of the Adriatic Sea.

Earth's mantle
Credit: Manon Knapen, based on My Science Box

With all the problems about the increase of CO2‘s concentration in the atmosphere, it is good to know that we get some help from the rocks. So, what have we learnt here? Rocks can do things! And the peridotite actually absorbs and mineralizes the CO2 atmospheric.

Knowing that, different companies are studying the cost of injecting CO2 in rocks. But that’s not a technology. That’s us, once again, wanting more from what Nature has to offer.

Where is the real technology? In Calera. Fonded in 2007, this company is actually using atmospheric CO2 and the process of carbonation to produce calcium carbonate. And finally they use it to make cement! Isn’t that great?

Even with this good news, be careful. Even if rocks can help absorb CO2 and some companies can succeed in doing the same, we still have the to limit our personal CO2 production. There are lots of simple things you can follow to reduce your carbon and you overall global ecological footprint!

Calera
Credit: Calera

Ready for a drive in a boxfish?

My best friend is doing some diving in French Polynesia. Getting samples for her PhD she told me, but I think she is mostly enjoying all the amazing sea life!

Of all the beautiful fish she will see in her explorations, I like the boxfish. First of all, because it is a weird looking fish. “Cute-ish”. And secondly, because we learnt something from it of course!

boxfishCredit: Erwin PoliakoffDoug Anderson, Keefer Milton / Flickr.

The boxfish can be found in the Atlantic, Indian and Pacific oceans where they live in beautiful coral and rocky reefs. Over there, they need to be very maneuverable, (like the Humpback whales!), stable, and fast at swimming between the reefs and get their food. And guess what? they have the perfect shape for it! I know, when we think about the perfect shape in the water, we probably all think of sharks. Long and slim, perfect at swimming straight. It thus seems counterintuitive that the boxfish could have a perfect shape since it looks like a box! But if the boxfish are still around, that means that they are adapted to their environment, right? So let’s find out how.

Stop thinking about the fast shark swimming around and think about other fish. How do they swim and what makes them good swimmers? What is their swimming routine like? Right, they don’t only swim straight. They turn a lot, go up and down, swim behind rocks and algae etc. You got the idea. To be good swimmers, fish don’t only have to be fast but also have to be agile.

What makes the boxfish a good swimmer?

Once again, it’s all about the shape! The box shape is actually a really good aerodynamic model. Indeed, tests made with a clay model showed that the drag coefficient of those square fish is extremely low, close to a drop of water (considered as the ideal aerodynamic shape). That means that it is quite easy for them to swim, and they don’t need to spend lots of energy. Besides that, there are also tiny vortices created on the front of their fins, which help the fish to be stable in turbulent water. If you’ve never seen a boxfish swimming, have a look at this video!

More than the shape, the composition of the boxfish is also important. As you can see on the picture below, the outside of the boxfish is composed of bones with a hexagonal shape. Yes, like the honeycomb! But why is that? Remember, the hexagon is the geometrical shape with the greatest surface area using the least material. An economic beast. Moreover, the combination of the hexagonal bones forms a rigid armor protecting the fish, almost like a shell.

Julia SumangilCredit : Julia Sumangil/Flickr.

All together, these characteristics attracted the attention of car designers. No exuberant car this time, but an actual everyday car.

In cars the drag coefficient (Cd) is very important, the bigger the drag, the more fuel you need. Thus, the lower the drag, the better. This is why the designers thought about the box fish, low drag (good aerodynamic), resistant structure, and the box shape is very practical for a car.

A computer simulation showed that the drag coefficient of the boxfish was 0.06, which is extremely low when you know that a truck is around 0.60 and a Toyota Corolla 0.30. Then, the concept car at a scale 1:4 got a Cd of 0.095, less good but still excellent. The company then created the actual concept car, 4.24 metres long, 1.82 metres wide and 1.59 metres high, and got a Cd of 0.19. Yup, that’s less exciting that the first computer results but it is still a big improvement compared to the average car (around 0.30).

But that’s not all. The designer also decided to use the honeycomb structure for the external paneling of the car. That resulted in a car 30% lighter and with up to 40% more rigidity compared to other structures.

By the end this concept car is more rigid, and lighter, than the classic car leading to reduced fuel consumption. (about 20% compared with a same size car, according to a Mercedes study).

Pablo Montesdeoca
Credit: Pablo Montesdeoca/Flickr.

Having a whale of a time!

Let’s talk about whales! Why? Because in less than two months I am going on a whale-watching tour, and hopefully, I’ll get the chance to see them! I already tried in 2012 after more than 11 hours in bus rides between Dunedin and Kaikoura, and didn’t even put a foot on the boat because of the bloody wind!

So, what can we learn from whales?

First of all, you need to know that there are two kinds of whales: the toothed whales, Odontocetes, which include Sperm whales, Belugas and Narwhals and baleen whales, Mysticetes, which include Blue whales, Right whales and Humpback whales. Instead of teeth, the Mysticetes have baleen plates made of keratin (like our fingernails and hair!). While the toothed-whales capture their meal with their teeth, the Mysticetes filter tiny animals out the water.

Today, we will learn a bit more about one Mysticete, the Humpback whale. This whale has developed particular techniques to get its prey, instead of swimming straight through a patch of prey like other Mysticetes, the Humpack whales can work in groups, creating columns of air bubbles in the water to concentrate the prey. Another technique they use is what scientists call “The inside loop”, the whale uses its flippers to complete super tight turns in the water. When approaching a patch of prey, the whale will swim down from the surface, then roll to make a sharp U-turn and rush back towards them to engulf the confused prey.

To achieve such tight turns and be able to swim under the prey while releasing bubbles, the whales must have something special… To find the answer, all you need is taking a look at their fins.

Fins comparison
Humpback vs Sperm whale
Look at their fins, they are different in size, but there is also something else!

Can you spot the difference? They have bumps on the forward edge of their flippers! Those bumps are called tubercles. Great, but so what?

To explain why these bumps are so important, I will switch to aeroplanes. Basically, when an aeroplane is flying, the air flows horizontally over it, which gives it lift during flight. But when the angle of the aeroplanes’s wing becomes too high, the airflow is broken, the lift decreases and the drag increases, this phenomenon is called a stall.

Aeroplane stall
Credit: Manon Knapen, adapted from Mysid/Wikipedia

Why is there no stall at every take off and landing then? Thanks to the deployment of flaps, but that’s a subject for another day. The important idea here is that when the wing angle is too big, there is a stall.

Time to go back to the Humpback whales: Just like the planes, whales can stall! When they try to turn too tight underwater, they can lose the water flow over their flippers, stall and thus, lose their prey. It is like driving a car around a corner and then slipping on ice; the car won’t follow the wheels, but skid off the road. Same here. Normally, the maximum flipper angle is about 11°, anymore breaks up the smoothness of the water flow over the flippers leading to the whales stalling. But it has been observed that the Humpback whales use their flippers at a higher angle (around 17°) before stalling occurs, which gives them an improvement close to 40%! This is all thanks to the presence of the tubercles on the leading edge of the flippers. Indeed, the flow between the tubercles creates small vortexes, preventing the flow separation, and thus stalling.

Good on them but what about us?

As tubercles delay stalling at high angles, it would be great to re-think the aeroplane shape, adding bumps on the wings. That would mean, no need of slots and flaps anymore (structures used to prevent stalling) making the areoplane slightly lighter, leading to fuel economy.

Future aeroplaneAeroplane prototype
Credit: Frank Fish, West Chester University

Besides this project, a company has already included tubercles in its product: Fan blades. The Envira-North Systems Ltd. is producing ceiling fans for big building like warehouses, factories and decided to add bumps on its fans, leading to an increase of efficient of 25% and a reduction of electricity consumption of 20%. Another positive aspect of the tubercled-fans is a noise reduction of about 20%.

Once again, I am fascinated by the result of evolution, making the Humpback flippers adapted to another way of feeding compared to the majority of other whales. I had never wonder why some flippers are smooth while others are bumpy. I hope that, like me, you enjoyed discovering something new today!

The Bottomless Bottle

Last night I had a dream… I was on trip through the desert! And, what a surprise, my bottle of water emptied super quickly. But then, what a miracle, the bottle slowly started to re-fill. Yes, I am quite obsessed by my blog and even dream about it. The self-filling water bottle is the new technology I want to talk about today!

Back to the desert: The Namib Desert of Namibia in Southern Africa. How dry is this desert? Have a look at the graph below for a quick estimation of rainfall: while New Zealand gets between 600 and 1600 litres per square meter per year, the Namib desert only gets 130! Five to twelve times less!

Rainfall comparison

Despite this arid nature, you can still see plenty of animals in the Namib Desert: antelopes, gazelles, gerbils, lizards and little creatures of huge interest: beetles.

Like every other animal living in a dry environment, the beetles have develop strategies to get water. While the Horny Devil  from central Australia had spikes on its back to collect water from the environment, the beetles have bumps!

JochenB
Credit: Jochen Bihn/Flickr

The shell of the Namib Desert beetle is covered by particular bumps. They are mainly hydrophobic (water repellent) but the top of each of them is hydrophilic (water attracting). What is the advantage of this? The water from the environment will only condensate on the top of the bumps, the water drop will get bigger and bigger, then, it will detach from the hydrophilic zone and roll between the others bumps (between the hydrophobic parts) straight to the mouth! Why is the accumulation of condensed water in big drops important? You don’t want to lose the water during the transport to the mouth! Drops too tiny would be lost because of the wind or would be completely evaporated before reaching the mouth! By accumulating water on top of each bump, then collecting them, there is a smaller loss of water.

The illustration below shows the difference of coating on the bumps. Indeed, a layer of wax is covering the sloping sides of the bumps, making them water repellent (hydrophobic).

Beetle's bump
Credit: Manon Knapen

Easy-peasy!

Now, you understand how my water bottle was self-filling in my dream! The company NBD Nanotechnologies is developing a self-filling water bottle, covering the outside of the bottle with a layer mimicking the bumps present on the beetle’s shell. Depending on the location, the bottle could collect up to 3 litres per hour. Can you imagine the impact of such a technology for all the countries facing water scarcity? I can’t wait to see the magic bottle on the market, hopefully in 2015!

Besides the self-filling bottles, other projects (tent covering, roof tiles, greenhouse) using the same technology are, again, still in progress. Collecting water in arid regions could become easier in the next decade and that is super exciting, so stay tuned!

Miguel Garces
Credit: Liz West/Flickr

Strongest ever

Question time: What is stronger than steel and more elastic than rubber?

Clue: I already talked about it in my post “Spiders to the birds rescue!”.

Yeah, spider’s silk! Last time we discovered how spiders were avoiding birds from smashing into their webs, today we will talk about the strength of the silk, how can they be so strong?

First thing we need to know is, where does the silk come from?  From the spinnerets! These hook-like organs are at the bottom of the spiders abdomen and depending on the species they can have 2 to 4 pairs of them.

Spider
Credit: Manon Knapen, modified from Spiber

A few days ago, I thought that there was only one type of silk, I was so wrong! There is actually up to seven different types of silk that can be produced. All these different silks are produced in glands within the spiders abdomen.

SpiberCredit: Spiber

Even if the different glands produce different silk (and all have a specific task) their structure is basically the same:

  1. A secretory part,
  2. A storage part,
  3. A funnel to reduce the diameter of the gland followed by
  4. A tapering duct where the silk fibres are formed, ending in
  5. A spigot from where the silk fibres emerge.

spider gland

 

The strongest, and most studied silk, is the dragline, which is secreted by the major ampullate gland. The dragline silk is used to make the lifeline (allowing the spider to move up and down) and to create its web.

The importance for us today is to understand what is the silk and how it is produced. To explore this, we will focus on the dragline. Any guesses about what is the main constituent of spider silks?

Proteins!
(For a quick reminder about proteins, go have a look at my friends blog!).

In this case, Spidroin I and Spidroin II, proteins from the Scleroprotein family like collagen (animal tissues) and keratin (hair, nails and outer layer of our skin). All these proteins have a very important structural role. In spider’s silk, the spidroins are structural proteins linked together to form long chains. Different chains can also interact with each other increasing the stability, but not too much so the structure keeps a bit of elasticity.

Those long chains of proteins will stay in a gel-like state in the storage part, ready to be used when needed.

Even if the whole process is still a bit unclear among scientists, Vollrath from Oxford University discovered that the duct was very important in the silk formation. The silk proteins are stocked in a liquid/gel phase, but when they enter the duct, the water is pumped away in another part of the duct! The proteins are dried of and this new environment leads to changes of configuration, creating more links between the proteins chains and in the end, harder silk.

Ok, now we know a bit more about the silk production. But why is the silk so strong? Structure, proteins structure! Spidroins are very particular, they possess different regions, one is highly stretchable, the two others are tightly folded and one of them is rigid (perfect to toughen the silk) but not the other. All together, they lead to a strong, tough and elastic material!

So strong that it is stronger than Kevlar, the material used for bulletproof vests! According to Vollrath, the silk is so strong and stretchable that it can be stretch up to 140% of its length without breaking.

What can we get from all this? Many many things actually! Lots of projects are still on the go but one day, we might find silk in our surgical sutures, bandages, cables, bulletproof vests, airbags, etc.

The only problem? Being territorial and cannabilistic, it makes it impossible to raise a spider farm to get silk! So the huge challenge for the scientists is to go deeper in to the reasons why the silk is so strong and then, try to recreate it in the lab. Currently they succeed in getting genetically modified silkworm to produce spider-like silk, but unfortunately it’s not as strong as the original one. Others are now trying to get the proteins produced by genetically modified bacteria (E. coli)! Good luck!

SilkwormSilkworm, caterpillar of the Bombyx mori.
Credit: Falevian