Lotus meets lizard

Improving on nature...

While the water repelling properties of the lotus leaf are the stuff of legend, like much in nature, scientists have found a way to replicate them. Superhydrophobic surfaces (as lotus leaf mimicking materials are known) have been around for years and they do repel water very well but, to date, the lotus has always had a leg up on them. Scratch a lotus leaf and, while its water repelling nature will be temporarily lost, the tissues will heal and the water repelling trait will return. Scratch any superhydrophobic surface and the water repelling trait is permanently lost. Now a team has found a way to help these surfaces heal themselves by mimicking another living organism: the lizard. The researchers created multiple layers of water proof material that were sandwiched together using water soluble glue. When the top layers became compromised, water seeped in, dissolved the glue, drove the top layer to fall off and exposed the undamaged water proof layer below. The material literally sheds its skin like a reptile. You can read more in The Economist article that I wrote on this here.

Colour me safer

In 1907 the Chicago Yellow Cab Company chose the colour of its cars based on a survey conducted at a nearby university. The survey showed that yellow was the most noticeable colour and led the company to infer that this would make it easier for potential passengers to spot their taxis in the sea of mass produced black cars prevalent at the time. Now, more than a century later, it turns out that yellow was a wise choice for a new study is revealing that taxis of that colour are much less likely to get into accidents than taxis of other colours.

The new work made use of a merger that took place between two taxi companies in Singapore during 2002. One of the companies used yellow cars and the other one used blue cars. Today, the company owns 4,175 yellow taxis and 12,525 blue ones. 

The researchers analysed 36 months of detailed taxi, driver, and accident data that the taxi company supplied to them and found that there is an unquestionable link between colour and accidents. In total, yellow taxis had 6.1 fewer accidents per 1,000 taxis per month than blue taxis. That suggested that colour alone granted a 9% reduction in accident probability. The researchers found this hard to swallow so they set off to explore whether the driver populations had any significant differences. To do this, they analysed the demography and driving behavior of a random sample of 3,341 drivers for 3 months using 15 second interval location and status data from the taxis. This amounted to more than 150 million data points and showed that the drivers were driving nearly identically. Mechanical differences were also ruled out since the taxi company uses a single car model and all cars undergo the same service schedules.

This led the team to question whether yellow taxis were protected by simply being more noticeable than blue taxis. To test this idea, the researchers delved into detailed accident reports and looked for the nature of the accident and the lighting conditions in which it occurred. They theorised that if yellow had a protective effect, a yellow taxi would be less likely than a blue taxi to be involved in an accident when the taxi was clearly in the other driver’s view. This proved true. They also theorised that yellow would grant an even greater advantage at night since yellow has a stronger contrast than blue against a dark background. You can read more in The Economist article that I wrote on this here.

The rise of robot bees

About to see meet some competition.

Image courtesy of John Severns.

Pollinators are in trouble and ecologists are scrambling to try to keep populations healthy. Economically this matters since a serious decline in pollinators has the potential to doom much modern agriculture but, just in case the ecologists fail, engineers are getting ready to handle the problem. Interested in creating pollinators from tiny drones, a team of researchers has designed and synthesised ionic liquid gels that will allow pollen to stick and be transported artificially.

Honey bees get covered in pollen when they enter flowers to collect nectar and then drop that pollen off in other flowers as they forage. This pollination allows plants to sexually reproduce and is vital to their survival. To date, nobody has been able to find a substance similar to honey bee fur that could readily capture and release pollen grains but the researchers behind the new work suspected that they could manufacture such a substance with ionic liquid gels.    

Ionic liquid gels are composed of electrolyte liquids trapped inside solid polymers. They are often electrically conductive, sturdy and have highly variable adhesive properties. This led the team to wonder whether it might be possible to create an ionic liquid gel that was sticky enough to collect pollen grains upon initial exposure to them but then capable of dropping the grains a minute later just as honey bee fur does as the insects rummage around inside flowers.     

To test this idea out, the researchers used an acrylic to polymerise an imidazolium salt, which is well known to function as an effective ionic liquid, by baking a mixture of the materials in an oven at 80˚C. Once the ionic liquid gel formed, they measured its tackiness with a probe by monitoring how much load it took for the gel to adhere and how much load was needed for the gel to release the probe once it was stuck to it. This test revealed that the gel was able to rapidly adhere under a very light load but would then release just as quickly when the same small load was applied in reverse. Crucially, the gel did not lose its adhesive properties after multiple attach and release events.  

Encouraged by these findings, the researchers applied the gel to horse hairs collected from paint brushes and then attached these hairs to their drones. They then manually piloted the drones to the flowers of the Japanese privet where they guided them to stick the hairs into the male and female organs of the plants. They studied the gel-coated hairs under the microscope between many of the flower visits and confirmed that they were getting coated in pollen. They then used fluorescent microscopy to confirm that pollination was indeed being initiated in the flowers that their drones visited. An abridged version of the research can be found in The Economist article that I wrote on this here.

The price of secrecy

While secrecy is common and consequential, there has been little research on it. Now a new study is revealing the sorts of secrets that people commonly keep. More importantly, it is revealing the first systematic analysis of how people experience the act of keeping a secret. As you can imagine, keeping secrets is hard work but whether having lots of secrets is actually harmful to our well being varies with how often we decide to think about them. You can read more in The Economist article that I wrote on this here.

Drunk crayfish

Woohoo!!!

Image courtesy of Jens Herberholz

Precisely what happens in the brain when we get drunk is still something of a mystery. This is largely because of the complex interactions between alcohol and the nervous system and one of the best ways of studying these interactions is to study the effects of alcohol on other animals. To this end a team of researchers ran a rather amusing experiment with juvenile crayfish. They found that, like many species, the crayfish were behaviourally sensitive to alcohol exposure and that they progressed through stages of intoxication that are strikingly similar to those seen in people. What came as an outright shock though was that the social history of the animals significantly modified the effects that alcohol had on them. Yeah, you read that right. Crayfish raised in tanks with many others got drunk far more quickly and became more dependent on alcohol than crayfish raised in isolation. The big question is whether social interactions during youth in people makes the brain vulnerable to alcohol in the same way. You can read more in The Economist article that I wrote on this here.