Geckos: Sticky Business
How geckos stick to surfaces has been a point of serious interest for some time to many scientists. Yet the solution continues to evade them and to prove more complex than first though. Their interest persists though because nature has been been working on these problems for the better part of 4.5 billion years and we could learn a lot from her! Mimicking nature is, unsurprisingly, called biomimickry and is a very useful tool in science. If we could figure out how to stick over and over again with the ease of the gecko it would be quite the achievement.
Scientists haven’t been idle twiddling their thumbs over the decades; it was first posited in 1934 that electrostatic forces may be the force behind the adhesive property of gecko. A researcher W.D. Dellit subjected the air surrounding the toes of the gecko to x-rays in order to neutralise any charges. He believed that this should have caused the gecko to fall if it were attached via electrostatic forces, however this did not occur. This lead him to conclude that the gecko must be employing another trick of nature.
Having crossed off electrostatic forces, curious minds across the world moved on and just over a decade ago a paper was published asserting that the adhesive property of geckos are due to van der Waals forces. These forces exist between touching surfaces such as a smooth windowpane and a gecko’s toes. But now, a new paper suggests that scientists were too hasty in ruling out electrostatic forces. Their first port of call is the adhesive force between the gecko and various surfaces. In their research they found that geckos can exert twice the adhesive force on Teflon AF than to polydimethylsioxane; these two materials are very similar in structure which made this result surprising. This lead the researchers to conclude that van der Waals are not the only forces at play.
Their second reason comes from a deeper understanding of how x-rays interact with their surroundings. The 1934 researcher, Dellit, was correct in saying that the x-rays should neutralise any electrical charges on the surface but did not know that the gaps between the grip pads on the gecko’s toes were too small to allow the ionized air particles between them. Thus the electrical charges would not have been neturalised.
It is also noted by other scientists that geckos have no trouble sticking to surfaces upon which electric charges do not accumulate, eg. bare steel and underwater. Thus it is noted that constant electrification does not seem to be necessary for adhesion. As the mystery deepens, the scientists realise that they have their work cut out for them in figuring out this complex problem.
Hercules Cluster | Abell 2151
This vista takes us back in time 500 million years, to a time when the Hercules Cluster itself was forming, a result of many mergers of smaller galaxies. Located some 500 million light years away, the cluster is filled with predominantly blue spiral galaxies. These blue spirals are filled with dust and gas, star forming regions and young blue hot stars. The cluster is surprisingly empty of older elliptical galaxies. It is also thought that this cluster is a good indicator as to how the universe may have evolved during its early days.
Seeing The Invisible
Part 1. Seeing Beyond The Visible Spectrum
The human eye, as fantastic as it is, is greatly limited in its ability to see the majority of the electromagnetic spectrum (light). Our eyes can generally see light with a wavelength between 780 nanometers and 390 nanometers and our brains interpret these differing wavelengths as different colours (below).
In order to see the other parts of the electromagnetic spectrum we have to create cameras which are sensitive them. For this astronomers have created telescopes for imaging everything from radio to x-ray! In the image of the galaxy Messier 106 (top) x-ray light has been given the false colour of blue and radio purple. These parts of the electromagnetic spectrum do not technically have ‘colours’ in the visible part of the spectrum but it helpful to give them a false colour to help us visualise them.
Part 2. Seeing The Distant
You know when you go outside at night and you look up and there is only one or two stars, and then you look up again half an hour later and the sky is awash with stars? This is due to your eyes adjusting to the dark and enabling you to see fainter things. One of the way your eyes achieve this is by dilating your pupils; this gives your eyes a greater light collecting area allowing you to see fainter things (below).
Astronomers do much the same thing with their telescopes by creating larger mirrors and lenses. Astronomers also have another trick up their sleeve to image the beauty of the universe. They take long exposure photographs! This means that they have a very long shutter speed on their cameras allowing more light to accumulate on the sensor at the back of the camera. We have all encountered the pitfall of having a long shutter speed during a photo - blurriness! In order to ensure that this does not happen in astrophotographs as the sky moves during the exposure, astronomers have telescope mounts which move very slowly and smoothly with the motion of the sky.
Best Exoplanet Candidate Ruled Out
I’m sure by now you have heard many times about earth-like exoplanet candidate Gliese 581 d and its status as most life-friendly planet (not including our own). Sadly a spanner has been thrown into the works as a new analysis of the system indicates that two of the potential six planets in the Gliese 581 system are most likely false positives. These two casualties are among the many that have been thrown into doubt in light of this new data.
So, what caused the data to indicate that the planets may exist? The original detection was achieved through the radial velocity method, wherein the gravitational pull of the planet on the star is measured. Using this data the period of the planets orbit can be inferred from the period of the graph and the mass of the planet can be inferred from the amplitude of the graph. However, when another team looked at Gliese 581 in the hydrogen alpha section of the spectrum they found that there are regions of magnetic activity that rotate with the sun that cause the illusion of planets Gliese 581 d and Gliese 581 g. There is, however, good news! While this analysis rules out the existence of planets Gliese 581 d and Gliese 581 e, it has strengthened the signal for planets Gliese 581 b, c and e.
Researcher Robin Wordsworth who lead the paper in 2011 that named Gliese 581 d the most likely planet of harbour life said that “If the new paper is correct, it’s a very disappointing result.” But, it was noted that “this is just the way science works”, and it is perfectly fine for results to be retracted due to new data.
Researchers warn that in the future, results may be more cautious and that they will do better to communicate the uncertainty of planets are they are released. One thing everybody can agree on is that it is great our understanding of exoplanets is improving, even if we lose a good candidate from time to time.
GravityLight - Light For Developing Countries
Brain child of two designers from the UK, this innovative light source aims to bring free easy to use light sources to developing countries. Approximately 1.5 billion people are without access to mains electricity and as such they will rely on biomass fuels such as hydrocarbons to light their homes after dark and as we know all too well: hydrocarbons environmentally damaging and not infinite in their supply. The designers sought to avoid these problems by finding a new way to power lights and they came up with an ingenious solution: gravity. The light can be suspending from most anything you can tie a rope to and in order to turn it you all that is required is for you to lift up a bag of dirt or stones. The bag hangs on a cord which is pulled through a weight drive similar to a cuckoo clock as gravity works its magic on the sack. Their current design can provide light for up to 30 minutes from just the three seconds required to lift the bag of dirt.
It is hoped once their campaign takes off they will be able to mass produce the lights for a cost of $5 per unit which is a tiny one off amount compared to the high ongoing cost that is required for biomass fuel lamps.. These lights also hold an advantage over solar lights in that they do not require any expensive, limited use batteries and can be used in period of overcast weather or at night for long periods of time.
Solar System Like Ours Discovered
Hidden in the huge amount of data gathered by the Kepler Telescope was the observation of a solar system a bit like our own, it consists of seven exoplanets arranged much like our own - rocky close in to the sun and gas giants further out. The system, KOI-351, was detected in early 2013 with three direct observations of planets with orbital periods of 59, 210 and 331 days. However, their orbital periods can vary by as much as 25.7 hours, which at first glance is a little strange. As all of the planets orbit within 1 astronomical unit (the distance of the Sun from the Earth) this variation was suspected to be due to tugs of as of yet unseen inner planets.
Using computer algorithms a team of scientists was able to detect four new planets in the system, bringing the total to seven. The four planets have orbital periods of 7, 9, 92 and 125 days thus making the system very compact. It is as of yet unknown why the system formed this way, and some scientists hypothesise that the system may be young and the planets may migrate outwards over the millions of years to come. It is hoped that an upcoming mission, PLATO, will receive funding and allow the scientists to have a second more detailed look at the system.
What Gives Summer That Distinct Smell?
As summer approaches us of the southern hemisphere we look forward to the sunny afternoons, the days at the beach and the smell of freshly mown grass - but what is that smell and why is it so relaxing?
When grass is cut, fats and phospholipids are broken down into long chain fatty acids, eg. linoelic acid, these fatty acids are then oxidised and chopped up by enzymes to form an end product that is either a six or twelve carbon chain. The six carbon chain molecule is the one responsible for the smell of grass so we shall focus on it. The molecules have a carbonyl group on the end and a double bond three carbons in from the end, and thus using some high school chemistry we can determine that the name of the organic molecule is cis-3-hexanal. Our noses are fantastic tools for discovering molecules and are particularly good at detecting this one; humans can detect cis-3-hexanal at 0.25 parts per billion. Cis-3-hexanal is very unstable and quickly mutates from a cis to trans - a molecule which is known as trans-2-hexanal. This molecule is known as the ‘leaf aldehyde’ and in part of what makes up commercial odours as ‘green odour’.
Cis-3-hexanal plays a role in many other aspects of life other than the smell of freshly mown grass - is it also important in the smell of strawberries, in the recovery of plants when they are damaged by pests and surprisingly in medicine. Studies have shown that molecules very similar to cis-3-hexanal can have a positive healing effect on the psychological damage caused by stress by activating blood flow in the primary olfactory cortex. So, maybe next time you’re having a rough day, go mow the lawn and spend some time sun bathing on your freshly trimmed grass.
Portable Hydrogen Reactors - The Future Is Here
You’re on the go and your phone just ran out of juice, maybe you have a portable charger handy but it’s not likely that you will get more than one charge out of it. But what if you had a portable power generator which could provide enough power to run your phone for a week? This is where the Brunston Hydrogen Reactor steps in; you may recognise that it bears some similarities to the Horizon Fuel-Cell MiniPak, which just so happens to be the device it was modelled on. The main changes seen between the two are the aesthetics, an increase in sturdiness in the Brunston as it is marketed towards hikers and campers, and higher capacity fuel cells.
So how does it work?
The 3-inch fuel cells are full of hydrogen which is stored as a hydride and this hydrogen is split apart using a platinum catalyst as to separate the positively charged H+ ions and the negative electrons and use them to create a electrical potential gradient, or, voltage. The device then routes the electrons through some wires and a USB port to charge your device, while the H+ ions are expelled through an electrolyte membrane where they combine with oxygen to form water vapour.
As the hydrogen is stored in a hydride its stability is increased and the device has been cleared for carry-on luggage in airplanes - however you cannot carry more than two hydrogen cells with you. The cells feature a 8,500 mAh capacity at an output of 5V with a choice of either 1A or 2A which you can select using a toggle switch. Once a fuel cell is depleted they can be charged again in about an hour, but sadly this ability will have to wait until you get home as the device used to charge them isn’t portable and requires a wall socket. Brunton is working to find a way to provide free in-store charging stations as the at home hydrolyser charging device costs $250.
I for one am very excited to see this awesome tech hit the market and may make use of it for my long trips into the mountains with my camera in the future! What would you use this tech for a what improvements would you like to see in the future?
NASA’s New Horizons Spacecraft
NASA launched its New Horizons spacecraft in early 2006 with the mission to study the planet Pluto, a trip which brought it past many other cosmic wonders on the long journey. On the dark side of Io you may be able to spot a blue cloud - this is a cloud of small particles which has been thrown into the atmosphere by volcanic activity and on Jupiter in false colour you can see the giant red spot in white (YOU HAD ONE JOB, NASA).
New Horizons took this image when it passed near by Jupiter in order to perform a gravity assist maneuver. In the case of New Horizons, its flight path was chosen to bring it in close to Jupiter in order to use its gravitational attraction to accelerate it and sling it towards Pluto at a faster speed it initially had. With its greater speed, New Horizons is due to reach Pluto in 2015 and is hoped to provide much interesting data including the global geology and morphology of Pluto and Charon, a map of chemical compositions of the two and many other things. You can read more about New Horizons’ objectives here.
Africa’s Fairy Circles - Mystery Solved?
Quite widely discussed, this phenomenon has baffled the world for many years with many myths popping up such a magnetism and various supernatural explanations offered as a solution, but recently scientific research has been put forward which may be a step towards a final answer - but maybe not. Termites.
Specifically, Psammotermes allocerus, a sand termite was proposed as the main contributing factor to the formation of the fairy circles. This comes after many years of arguing back and forth with a professor of Botany from Pretoria ruling out termite activity, radioactive soil and plant toxins as factors in 2004.This was followed by a reply in 2008 by Angelique Joubert that a small flowering plant, Euphorbia damarana could be the cause, but no carry up on this proposition has been noted. Continuing from this in 2012 Eugene Moll suggested that two termite species, Baucaliotermes hainsei and Psammotermes allocerus could be the creators of the circles. This was then backed up in 2013 by another scientist who found that in 80%-100% Psammotermes allocerus was active and that it had a 100% occurrence rate in newly formed circles.
Research has shown that the termites do indeed create a fairy circle by consuming vegetation, and this continues to back up the theory put forward by Eugene Moll. However while the research has garnered much interest it is not widely accepted as the case as correlation is not the same as causation and until a causal link can be shown, it could potentially just be chance that the termites are on the sites.
What do you think? Are the termites likely to be the cause, or is this just very strong correlation? What other cause would you propose?