Making Metals (More) Interesting

Metals are boring. Sure, they’re nice and shiny. And they’re definitely useful. But could you honestly, hand on your heart, say that the last time you saw a bit of metal you jumped for joy? Probably not.

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Metals: a bit boring?

The trouble is, we’ve been playing around with chunks of metal for so long that the novelty has worn off. You can melt down metal and create swords, axes and other cool things. That’s pretty neat, but it’s not exactly cutting-edge technology (see what I did there?). You can melt metals and mix then up to get alloys, which are awesome for jazz bands (brass instruments) and eating (stainless steel) among many other uses. Don’t get me wrong, I’m a great stickler for jazz and a big fan of the classic knife and fork combo, but neither of those things are particularly new.

Worse still, as a physicist working in the realm of optics whose job is to find things, shine light on them and see what happens, I find chunks of metal truly boring.

Fortunately for us optical physicists, lots of researchers in other fields were having a similar problem and suggested a solution: make things really really small and try measuring them again. The beauty of nanoscience is that conventionally boring materials can be made interesting again by studying them on the nanoscale (billionths of a metre). A recent example of this approach can be found in the world of carbon. Graphite is a pretty boring form of layered carbon atoms (as found in pencils), but reducing a piece of graphite down to a single layer (graphene) makes weird stuff happen.

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Metal nanoparticles in stained glass windows: quite a bit more interesting.

What happens, then, when we shine light on tiny pieces of metal? It turns out we’ve had the answer right before our eyes for centuries without even knowing it. The brilliant colours we see in stained glass windows are caused by pieces of gold or silver a few tens of nanometres across. These pieces of metal absorb extra wavelengths of light which they wouldn’t absorb if they were of a more “conventional” size. Change the size of these metal nanoparticle by a few dozen nanometres (say, from 80 nm down to 50 nm) and the wavelengths of light they absorbed (and so the colour of the glass they are dispersed in) changes. This is all a bit weird, isn’t it? Compare a gold ring with a bar of gold, or a gold statue, and they all look to be the same colour – even though we’ve gone from something a few millimetres in length to something on the order of a metre. Yet change the size of a nanoparticle by a mere 10 or 20% and we get an enormous change.

So, what’s going on?

It all comes down to everybody’s favourite subatomic particle, the electron. Metals are made of regularly arranged atoms, this arrangement leaves one of the electrons (or more, depending on the metal) from each atom free to wander around the atomic lattice more or less as they feel. These delocalised electrons can be made to move in an ordered way by giving them energy. For example, by applying a voltage across a long, thin piece of metal (commonly known as a “wire”) the delocalised electrons will all flow along the metal in the same direction – this is electricity. But attaching crocodile clips to metallic nanoparticles is, as you can probably imagine, rather tricky. Instead we can induce collective motion in a nanoparticle’s delocalised electrons by shining light at it. In a nanoparticle, the delocalised electrons are confined to a small region, and they will strongly absorb certain wavelengths of light and convert this energy into collective oscillations. These light-induced electron oscillations are known as plasmons. The wavelength of light which excites these plasmons depends on the size of the particle but also on their shape and electron density (which in turn depends on the metal used).

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The principle of plasmon resonances in metallic nanoparticles.

The fun doesn’t stop with stained glass windows, either. Tuning the properties of metal nanoparticles, placing them in arrays and combining them with other materials allows for all kinds of weird and wonderful properties with potential applications in biosensing, optoelectronics, cancer therapy, and possibly even invisibility cloaks (each of which will be discussed in subsequent blog posts). Best of all for a generation of bored metal-optics researchers, this cocktail of weird results means that metals have once again become interesting and will likely remain interesting for some time.

Post by: Philip Thomas

 

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Webcam astronomy: simple but effective

Over the past 4 years, I have been steadily assembling equipment for the purpose of photographing deep sky objects (DSOs). These are dim, sometimes large, diffuse cloudy patches when viewed using binoculars or a small telescope. Starting with the Andromeda galaxy (see below), I used a simple, long tube telescope fitted to a tracking mount (that tracks the DSO as it moves across the night sky). This allows a camera to collect light over a long period of time (often up to several hours) showing features that would otherwise be far too dim to detect with the naked eye.

The Andromeda galaxy (M31) taken by collecting over 2 hours of photographic exposures.

The Andromeda galaxy (M31) taken by collecting over 2 hours of photographic exposures.

Although I personally find this type of astrophotography very rewarding, there are some major drawbacks. The first and most severe is how sensitive this type of photography is to unwanted light. Since photographing DSOs requires a really long exposure, any stray light from streetlights or the Moon simply washes out the object’s detail. The second is the sheer time it takes to collect the light to produce these types of photographs. The main issue is that as I take these long exposures (typically I take over 30 shots each lasting up to 5 minutes), any disturbance such as a gust of wind or nearby movement can cause the image to smear.

Mainly for these two reasons, I decided recently to branch into a different type of astrophotography – webcam astrophotography. Although I don’t have any pictures to show yet (I haven’t finished modifying the webcam yet, but watch this space!) I will briefly discuss the principles of this form of astrophotography and how it can be achieved with very limited equipment (and budget).

Put simply, webcam astrophotography involves taking a video of a bright night sky object (such as a planet or the Moon) and using the best frames of that video to produce a high quality image. There are several advantages to this approach. Firstly, since the object you are photographing will be bright, the exposures are short. This means that movement of the telescope will not cause image smear. In addition, the telescope mount does not have to track the night sky very accurately since each frame of the video is taken over a fraction of a second (normally 1/30s). Secondly, bright objects far outshine artificial light pollution, which makes this form of astrophotography very suitable for people living in towns and cities.

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Photo of a bird with strong chromatic aberration caused by improperly focused violet light.

So, with a webcam and a cheap telescope mount, some impressive   astrophotography can be achieved (see this link). However, I have neglected to mention anything about the telescope. When photographing bright objects overcoming chromatic aberration (CA) is a real problem. This optical aberration occurs when light being focused through a lens splits into its constituent colours and these colours focus at different points. The colour fringing effect caused by CA is shown on the right.

So, I decided t20160130_093248o use a telescope design known as a Maksutov-Cassegrain (modelled by my lovely fiancée Sarah) that avoids CA through an ingenious use of lenses and mirrors. There are three important advantages of using this telescope. (1) The light entering the telescope does not split into different colours (as mentioned). (2) Light is also neatly folded up so the actual telescope is conveniently small. Finally, although the telescope is short, it is capable of imaging at high magnification – an important feature if you wish to image small Moon craters or the great red spot on Jupiter.

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A excellent image of Jupiter taken using a Maksutov-Cassegrain telescope and a cheap webcam. Photo credit: Dion from the Astronomy Shed.

In hindsight, perhaps I should have started my astrophotography hobby with webcam imaging; I would have saved a lot of time and money and not developed an irrational hatred of streetlights or the Moon!

Post by: Daniel Elijah

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The science behind the headlines: How Chemotherapy could change the lives of thousands suffering from MS.

MS is one of the most common neurological disorder affecting young adults in the western hemisphere, indeed the list of sufferers include a number of high profile names.

oligo-253x300Although scientists are still unsure of exactly what causes the disorder, they do have a good working understanding of disease progression. Symptoms stem from damage to a fatty covering which surrounds nerve cells, known as a myelin sheath. It is this myelin which allows neurons to communicate quickly with one another through a process known as saltatory conduction. In brief, cells called oligodendrocytes (in the central nervous system) and Schwann cells (in the peripheral nervous system) reach out branching protrusions which wrap around segments of surrounding neuron forming a sheath (see image to the left). Signals traveling through myelinated neurons are able to move rapidly by ‘jumping’ between gaps in this sheathing known as nodes of Ranvier. In the case of MS, damage to this sheath causes signalling between neurons to slow down, leading to a range of symptoms.

It is believed that, in the earliest stages of the disease, the body’s own immune cells (cells usually primed to seek out and destroy foreign agents within the body, such as viruses and parasites) mistake endogenous myelin for a foreign body and launch an attack.

Most current treatments focus on suppressing these immunological attacks by inhibiting the patients aberrant immune response. However, this novel and arguably ‘brutal’ new treatment focuses on destroying the patients existing immune system before re-building it again from scratch.

To understand how this treatment works, it is first necessary to give a bit of background into the immune system. Specialised immune cells, designed to protect our body from disease, are generated in our bone marrow. It is these cells which ‘misbehave’ in autoimmune diseases such as MS and can launch an attack our own cells. Key to this process is the existence of hematopoietic stem cells (HSCs) within the marrow. These cells are precursors to all other blood cells (including immune cells) and, given the correct environment, can develop into any other blood cell (see image below).
1024px-Hematopoiesis_simple.svg
This new treatment requires three important steps:

First, it is necessary to harvest a number of these amazingly versatile HSCs from the patients and store them for later use. HSCs are either collected directly from a patients marrow through aspirations performed under general or regional anaesthesia or harvested directly from blood following procedures intended to enrich circulating blood with HSCs. Since HSCs make up only 0.01% of total the nucleated cells in bone marrow, these must be isolated from samples (based on either cell size and density or using antibody based selection methods) and purified before undergoing cryopreservation.

Next, the patient undergoes chemotherapy, with or without the addition of immune-depleting agents. The purpose of this is to eliminate disease in the patient, specifically by destroying the malfunctioning mature immune cells which are erroneously targeting and destroying healthy myelin. Since chemotherapy has a severe toxic effect and can cause damage to the heart, lungs and liver this procedure is currently limited to younger patients.

Finally, the cryopreserved HSCs removed in step one are reintroduced into the patient, a process called hematopoietic stem cells transplantation (HSCT). Given time, these stem cells develop into new immune cells therefore reconstructing the patients immune system. At this stage it is possible that mature, faulty, immune cells may be transplanted back into the patient from the original sample. Therefore, before transplantation procedures are carried out to ensure that few mature immune cells are contained within the transplant.

Each of these steps comes with it’s own scientific challenges, not to mention challenges for patients including the hair loss and severe nausea linked with chemotherapy. But, so far, this treatment has also lead to some absolutely amazing success stories with one, previously wheelchair-bound, sufferer regaining the ability to swim and cycle. However, doctors stress that this is a particularly aggressive form of treatment and that it may not be suitable for all MS sufferers.

Dr Emma Gray, head of clinical trials at UK’s MS Society, said: “Ongoing research suggests stem cell treatments such as HSCT could offer hope, and it’s clear that in the cases highlighted by BBCs Panorama they’ve had a life-changing impact. However, trials have found that while HSCT may be able to stabilise or improve disability in some people with MS it may not be effective for all types of the condition.”

Dr Gray said people should be aware it is an “aggressive treatment that comes with significant risks”, but called for more research into HSCT so there could be greater understanding of its safety and long term effectiveness.

Post by: Sarah Fox

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The astronomy of astrology

It’s been a while since I last posted so instead of talking about the details of using telescopes or taking astrophotographs, I will discuss what for many people are two interchangeable terms: astronomy and astrology. More specifically, this post shows how some interesting oddities of astrology can also interest astronomers.

As a reminder, astrology is the study of the movements of celestial objects with the goal of predicting or justifying life events while astronomy is the scientific study of the properties, interactions and evolution of celestial objects. While I feel that our life choices are not influenced by the movement of the Sun across the zodiac constellations, or the alignment of certain planets I do think that people who believe in astrology may find significant interest in the evidence-based view of the universe astronomers take.

Lets begin by discussing an interesting tenet of astrology: star signs. The 12 signs of the western zodiac are based on the constellations which lay along the path on which the Sun appears to travel over the course of a year. Your star sign should ideally relate to the constellation which the Sun passes through on the day of your birth. But, most the time things are not this simple.

Every year, as the Earth orbits the Sun, the line of sight between us and one zodiac constellation is blocked by the Sun, this means that, as viewed from Earth, the Sun will appear to be sitting within this constellation. However, the dates associated with the star signs have not been technically correct for around 2000 years, i.e. the constellation in which the Sun appears the day of your birth may not fit with your star sign.

This is caused by a discrepancy between the way we define a year and changes in the movement of the Earth. As a society, we define a year as starting on a set date (the 1st of January) and running for a given number of days (365 – or 366 on a leap year). However, a year in astronomical terms is defined as the time it takes for the Earth to revolve once around the Sun, and these two measurements do not necessarily match up.

Figure 1. The position of the vernal equinox in the night sky. The Sun currently passes through this point on the ecliptic (red line) on 20th March. Graphic taken from Stellarium.

Figure 1. The position of the vernal equinox in the night sky. The Sun currently passes through this point on the ecliptic (red line) on 20th March. Graphic taken from Stellarium.

Specifically, in astronomical terms a year consists of the time period between vernal equinoxes. The vernal equinox occurs when the ecliptic (the line the Sun makes across the sky in one year) crosses the celestial equator (an imaginary line projecting out from Earth’s equator into space), see the blue arrow in Figure 1.

However, due to the fact that the Earth slowly wobbles on its axis every 26000 years (called Precession), the date of the vernal equinox slowly shifts by about 1 day every 70 years. The effect of this shifting equinox is that the position of the Sun within different constellations slowly changes, therefore, the Sun may be in a different constellation during the month of your birth than it was when astrological charts were first drawn up. Below is a table comparing traditional star sign dates with the actual position of the sun on these dates.

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The table also includes the length of time the Sun spends in each constellation. As a convenience in astrology, the star signs are given equal lengths. However, in reality, constellations have different sizes and cut across the ecliptic at different angles. The Sun spends 44 days in the constellation Virgo but only 8 days in Scopius (making true solar Scorpios a rare breed!). You may also notice an unfamiliar constellation: Ophiuchus (the serpent barer), it’s a large constellation but only a small part of it is actually crossed by the Sun in early December. Strangely this was known in ancient times but not included as a sign of the zodiac.

Gemini - 2015 Gemini - 28015Figure 2. The motion of the stars over thousands of years changes the constellations. Nearby stars (such as Pollux) appear to move faster. Graphic taken from Stellarium.

Gemini – 2015
Gemini – 28015Figure 2. The motion of the stars over thousands of years changes the constellations. Nearby stars (such as Pollux) appear to move faster. Graphic taken from Stellarium.

So when will the traditional star sign dates once again match up with the position of the sun within these constellations? Well, this could happen in about 24000 years, after the Earth has completed a full precession rotation. However, by then the stars themselves will have moved relative to each other, changing the shape of the constellations forever. In Figure 2, the constellation Gemini (my true solar star sign) is shown as it appears now (2015), and how it is projected to appear after 26000 years of star movement (date 26000 + 2015).

All of this serves as a reminder that the universe does not neatly fit into equally spaced constellations or fixed calendars, instead it is amazingly complex and constantly changing. So perhaps astrology can be a starting point for peoples’ interest in the universe, or at least to getting a better understanding of the science behind the horoscopes.

Post by Daniel Elijah

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Animal consciousness

When I was a child, living in Poland, we believed that on Christmas Eve animals can speak human language. I waited till the magical time – midnight, and listened, but our dogs and cats did not take the opportunity to tell us what was on their mind. This tradition could have originated from the belief that the spirits of our ancestors could speak through the animals, or perhaps it referred to the presence of animals at the birth of Jesus. Either way, some scientists think that other species of animals have more in common with us than we think.

Bottlenose dolphins hesitate and waver when they are uncertain of the correct answer. Image by NASAs [Public domain], via Wikimedia Commons

Bottlenose dolphins hesitate and waver when they are uncertain of the correct answer. Image by NASAs [Public domain], via Wikimedia Commons

You might not be surprised to hear that dolphins have the skill of metacognition, that is the ability to think about, or oversee, their own thinking (Smith et al., 1995). In humans metacognition is related to self-reflection and self-awareness (Smith et al., 2012) . An example of this ‘thinking about thinking’ is the ‘tip-of-the-tong’ experience (when you are sure that you know something but cannot quite bring it to mind).

Researchers presented dolphins with sounds of different pitch, asking the animals to indicate the pitch of a given sound by touching response paddles (Smith et al., 1995). They increased the difficulty of the task by making some sounds very similar, therefore confusing the dolphins. In recognition that some sounds would be hard to differentiate, the dolphins were given the option to press a paddle indicating that they were ‘uncertain’ of the pitch of the sound. The ability to decline completion of a task due to uncertainty is an important aspect of metacognition. In humans the answer ‘I don’t know’ is thought to be based on the internal reflection: how likely is it that I will respond correctly? The less certain we are of our response, the more we hesitate. The dolphins in the experiment did indeed use the option ‘uncertain’ to decline completing the task when they thought it was too difficult. Moreover, this uncertainty was reflected in their behaviour:  when sure of the response, dolphins swam towards the paddles so fast that the splash sometimes damaged the experimenters equipment. On the other hand, when they did not know the answer, they slowed, wavered and hesitated.

Monkeys know when they do not know. Image by Jack Hynes [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Monkeys know when they do not know.
Image by Jack Hynes [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Other animals also showed the ability to monitor their own thinking. Similar to results seen in dolphins, macaques also show signs of metacognition. Specifically, when asked to decide whether the number of dots on the computer screen was smaller or greater than a value that they had learned before (Beran et al., 2006), macaques showed signs of hesitation and uncertainty when the task was hard. Other researchers asked the monkeys to match currently presented images to previous samples (Hampton, 2001). The more time elapsed between the pictures, the more ‘uncertain’ responses the animals gave. This was interpreted as an example of meta-memory – the ability to monitor our memories and decide whether they are clear enough to give a correct answer.

Does this mean that at least some animals, such as monkeys and dolphins, have consciousness? That depends on the definition of consciousness. Is hesitating and worrying about own performance enough? Do we need more sophisticated tests? Perhaps some of us  (especially those living with pets) need no tests at all to feel that we have a lot in common with non-human animals and that we share our existence with them.

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The Whaling Industry – Dubious or Justified?

Whaling is a big part of human history. The Norwegians have been whaling for over 4,000 years and the Japanese for even longer. No matter what your personal feelings and opinions of whaling, it is a historic practise that is still being used today.

800px-Whaling_in_the_Faroe_IslandsBeginning in the 1960s there has been a sharp decline in the number of whales killed by hunters. This hasn’t been due to a lack of need for whale meat but, rather, as a result of there simply being fewer whales. Whales have gestation periods of 7-13 months and very rarely have more than one calf at a time. When you consider that thousands were once being killed each year, it’s easy to understand why they were unable to maintain their population numbers.

As fewer and fewer whaling ships were meeting with success, the International Whaling Commission was set up in 1946 to try and solve this problem. It tried to help by placing protection orders on certain species of whales that had suffered the most. All whale populations continued to decline though so, in 1986, the commission placed a complete ban on whaling for all its members.

This ban is still in place, however, due to loopholes, over 30,000 whales have been hunted

and killed since 1986 by members of the International Whaling Commission. This mainly comes from three countries – Iceland, Japan and Norway. Iceland left the Commission and then re-joined under a ‘reservation’ whereby it didn’t have to recognise the ban, although this has actually caused some countries to not recognise Iceland as a member.

Japan makes use of a loophole permitting hunting for scientific research, however they have just last year been told that at least one of these research programmes involved killing unnecessarily. Killing whales for research purposes may first appear to be more understandable than commercial hunting but in Japan, when the research has finished, the whale’s carcass is sold and a profit is made. Of course, not everything is as straightforward as it may first appear, but it really does seem to be a commercial venture that just has to allow the bodies to be first used for research.

762px-The_King_of_the_Seas_in_the_Hands_of_the_Makahs_-_1910Out of the three countries, Norway is the only one that appears to be upfront about its opinions. The Norwegians made it clear when the ban was coming into place that they didn’t agree with it and, instead of trying to use smoke and mirrors to hide their intentions, they have carried on whaling openly. This may not be agreeable but somehow appears a lot less morally dubious to my mind.

There is one final exception to the ban, which pertains to Aboriginal Substance Whalers. These are communities that hunt using traditional methods, carrying on the practises their ancestors began. The International Whaling Commission recognised the need to preserve this way of life and protect these communities’ culture. Therefore, in the terms of the ban, they are allowed to hunt whales if no profit is made.

There can be a lot found about whaling in the media, often from very extreme sides. It’s not just whales that are hunted in the oceans (think of all the fish in the fishmongers). Yet even species whose numbers are running low don’t receive nearly the same attention from the media as whales. Why? Well, simply because we are humans and can empathise with mammals more easily than with other animals.

This doesn’t mean that caring about whales is wrong, it just means we need to view the facts when it comes to the whaling industry. We need to think about which countries allow whaling, and why they do it. We need to think about the role the whales have in the ecosystem. We need to balance facts. You may be for whaling, you may be against it, but a clear fact is that hunting is possible without causing such a crash in the population numbers as has been seen in the case of whale species.

Post by: Jennifer Rasal

References:

http://uk.whales.org/wdc-in-action/whaling

Why are whales killed?

https://iwc.int/home

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Cleaning Air with Poetry: Surprising Uses of a Titanium Dioxide Catalyst

The 21st Century has brought with it a growing acceptance of the severity of climate change, with Forecasts of the Intergovernmental Panel for Climate Change (IPCC) projecting a 2°C rise in global temperature by 2050 based on current levels of greenhouse gas emissions. The recent Paris Agreement of the 2015 United Nations Climate Change Conference brought a global consensus to make efforts to limit the global temperature rise to 1.5°C by 2050. However, despite such promising commitments, the majority of measures to combat global warming and anthropogenic pollution have so far been directed only towards the prevention of further damage being done. It is likely that more innovative methods may be required to help reverse the accumulation of greenhouse gases and to improve the air quality of urban environments, where smog is having a severe effect on public health.

One such innovation with green potential involves a clever application of catalytic nanoparticles. Refreshingly, this innovation originated from collaboration between the arts and science, and is invigorating in its use of the natural curiosity and creativity of humanity to address man-made issues. Through this article, I aim to describe to you how you yourself can assist in removing harmful pollutants from the air simply by walking along a street, or even just by reading a poem.

Pollutive gases can be broadly divided into two groups: The greenhouse gases (such as methane, carbon dioxide, and nitrous oxide), which absorb radiation in the upper atmosphere, and toxic surface-level pollutants (such as carbon monoxide, volatile organic compounds, and nitrogen oxides (NOx)). Surface-level pollutants are predominantly derived from industrial or transport emissions, and in London alone are believed to be responsible for thousands of premature deaths every year.

Actively reducing levels of air pollutants is likely to require some form of catalytic process (put in mind the catalytic conversion of carbon dioxide to oxygen performed by plants), and so efforts have recently been made to neutralise toxic surface-level pollutants through use of synthetic catalysts in urban environments (where both the concentration of pollution, and people, is at its greatest). These catalysts hold significant promise for the future, and it was through the work of Prof. Tony Ryan that I was first introduced to the potential of one such catalyst, the titanium dioxide (TiO2) nanoparticle.

CatClo-treated jeans displayed in Sheffield’s Winter Garden. Photograph courtesy of Helen Storey Foundation.

CatClo-treated jeans displayed in Sheffield’s Winter Garden. Photograph courtesy of Helen Storey Foundation.

Nanoparticles are materials on the scale of a millionth of a millimetre. With such miniaturisation comes a substantial increase in available surface area on which reactions can take place, and often a change in chemical properties. When exposed to sunlight, TiO2 nanoparticles provide a catalytic surface for the production of peroxides, which can then react with nitric oxide to produce nitric acid and nitrates, effectively removing the toxic nitric oxide from the breathable atmosphere (1,2).

The current applications of TiO2 nanoparticles include the coating of walls and windows of buildings, and surfaces of pavements and roads (3,5), although the true motive behind this use is not to reduce pollution. TiO2 nanoparticles also confer a self-cleaning property as the lipophilic TiO2 attracts a layer of water between a surface and dirt particles, allowing dirt to simply wash away with rainfall. By such applications alone, concentrations of nitric oxide have been shown to fall by 20-60% (6,7).

A particularly inspirational use of TiO2 nanoparticles arose from the collaboration between Prof. Ryan and the fashion designer, Prof. Helen Storey. This meeting of arts and science led to the development of CatClo, a laundry additive of TiO2 nanoparticles which, when washed into clothing, imbues them with the nanoparticles’ photocatalytic quality. It is predicted that CatClo-treated clothing would remove roughly 5 grams of nitric oxide per day when worn in an urban environment, equivalent to the daily nitric oxide emissions of the average car (8). Although the CatClo additive is eventually removed by subsequent repeated washes, the additional antibacterial effect conferred by the nanoparticles may extend wearable time between washes.

Prof. Ryan has further demonstrated the versatility of TiO2 nanoparticles through an art installation involving prestigious poet, Simon Armitage. Penned by Armitage, a poem entitled ‘In Praise of Air’ was displayed in the centre of Sheffield, printed on 10 m x 20 m material ingrained with TiO2 nanoparticles. This installation was estimated capable of removing the nitric oxide emissions of as many as 20 cars daily.

Installation of the “photocatalytic poem”, In Praise of Air, in Sheffield. Present are Simon Armitage (right), and Prof. Tony Ryan (left). Photo from www.sheffield.ac.uk.

Installation of the “photocatalytic poem”, In Praise of Air, in Sheffield. Present are Simon Armitage (right), and Prof. Tony Ryan (left). Photo from www.sheffield.ac.uk.

Just such a merging of arts and science is what separates the projects of Prof. Ryan from other scientific endeavours combating climate change, and it stands as a striking example of how the applications of an invention can be brought to a wider audience by simple, yet creative, means.

More information can be found regarding CatClo at www.catalytic-clothing.org

Post by: David Young

References

1.    Ohko, Y., Nakamura, Y., Fukuda, A., Matsuzawa, S. & Takeuchi, K. Photocatalytic Oxidation of Nitrogen Dioxide with TiO2 Thin Films under Continuous UV-Light Illumination. J. Phys. Chem. C 112, 10502–10508 (2008).

2.    Toma, F. L., Bertrand, G., Klein, D. & Coddet, C. Photocatalytic removal of nitrogen oxides via titanium dioxide. Environ. Chem. Lett. 2, 117–121 (2004).

3.    Shen, S., Burton, M., Jobson, B. & Haselbach, L. Pervious concrete with titanium dioxide as a photocatalyst compound for a greener urban road environment. Constr. Build. Mater. 35, 874–883 (2012).

4.    Chen, J. & Poon, C. Photocatalytic construction and building materials: From fundamentals to applications. Build. Environ. 44, 1899–1906 (2009).

5.    Hüsken, G., Hunger, M. & Brouwers, H. J. H. Experimental study of photocatalytic concrete products for air purification. Build. Environ. 44, 2463–2474 (2009).

6.    TX Active® The Photocatalytic Active Principle. (2009). http://www.italcementigroup.com/NR/rdonlyres/96036B14-4C6D-4E07-9854-1B1CE1AD6593/0/TXactivetechnicalreport2009.pdf

7.    Tx Active®. (2006). http://www.italcementigroup.com/NR/rdonlyres/1F30E487-C0A2-4D6F-AB6D-C14555FD866F/0/Scientificresults.pdf

8.    Pollution-busting laundry additive gets set to clean. Sheffield.ac.uk (2012). https://www.sheffield.ac.uk/news/nr/catclo-tony-ryan-london-college-fashion-air-purification-nanoparticles-1.211918

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