Bendy solar cells, turning CO2 to stone, and antibiotic resistance
Chemistry, Biology, Physics: Three scientists talk through big recent developments in their fields.
This article is a preview from the Autumn 2016 edition of New Humanist. You can find out more and subscribe here.
Biology – Lydia Leon
The development of penicillin ushered in an era in which the dominance of infectious disease was challenged across the world. Antibiotics have saved millions of lives. However, in recent years there has been panic at sobering and increasingly common reports of anti-microbial resistance (AMR), in which strains of bacteria have evolved to make many antibiotics ineffective at killing them. AMR is estimated to cause 700,000 deaths a year, with some projections citing a growth to as many as 10 million by 2050.
A recent report commissioned by David Cameron set out suggestions for concrete actions.The authors highlighted four critical points of focus: a global public awareness campaign, the need to use antibiotics more sparingly, the reduction of unnecessary use in agriculture and finally, tackling the desperate need for new drugs.
There might be hundreds of antibiotics on our pharmacy shelves – but they can be grouped into much smaller functional categories based on the way in which they kill the bugs. The last new functional class of antibiotics was in 1987 – almost 30 years ago.
There is cause for cautious optimism. Firstly, following the introduction of financial incentives last year, the NHS saw a 7.9 per cent reduction in the prescription of antibiotics between April and December, compared to the same time in 2014. Such trends must continue.
Secondly, in July a group from the University of Tübingen, Germany, published a paper in the journal Nature that documents the discovery of lugdunin, a new antimicrobial molecule. Isolated from bacteria living within the noses of study participants, it was able to kill one of the deadliest strains of resistant bugs: MRSA. The research provides promising evidence that the human body itself may be a fruitful source of new antibiotics – until now the vast majority have been isolated from bacteria living in soil.
If such developments are to result in new and effective treatments, there must be incentives to encourage industry and academia to reengage with a fight that many thought won decades ago, but that is clearly far from over.
Lydia Leon is a PhD student at University College London
Physics – Ceri Brenner
Yesterday I walked 16,901 steps and last night I met my sleep target of eight hours for the first time in ten days. I’m enjoying my fitness tracker. However, I’m not a fan of having to search out the charger every two to three days. Whilst this is a classic entry for #firstworldproblems it becomes a real limitation for the development of wearable technology for things like medical monitoring or military navigation. In these circumstances, low battery could cause real danger.
One of the best solutions is to exploit the sun’s rays for power generation in a design that seamlessly integrates solar technology. For this you need solar cells that are very thin, flexible and durable. A group recently published their ultra-bendy design in the journal Applied Physics Letters, in which the miniature solar cells were installed onto a flexible substrate that is only a few microns thick (for reference, human hair is about 100 microns wide). They mounted the cells on top of metal electrodes embedded into the substrate using a method that, to me, resembles how transfer tattoos are applied.
The electrical performance shows their stacked, transfer-printed concept works equally well alongside traditional, but thicker, designs in which the solar cells and electrode are mounted side by side. Despite the new design containing less solar cell material, the boosted efficiency is attributed to the vertical mounting, since the metal electrode plate is reflecting any unabsorbed light back up towards the solar cells so as to increase the chance of energy capture. Their paper also includes some cool photos of their highly flexible microcells attached to fabric and glass, including wrapped around a cotton-bud stick.
Solar power is a beautiful concept, exchanging the natural clean resource of sunlight energy that we are bathed in every day into electrical energy that we can use as we please. The more we can do with solar power, the better. I would gladly do away with the USB cable to coat my smart watch with this solar tape.
Ceri Brenner is a physicist who works for the Science and Technology Facilities Council
Chemistry – Mark Lorch
If our addiction to polluting fossil fuels can’t be brought under control then we need to find some other way to limit the emissions of carbon dioxide that are causing climate change and acidification of the planet’s oceans. Carbon capture and storage is one option; CO2 can be trapped at the point of production and stored, typically in disused natural gas fields or oil wells. This could work, however there are fears the CO2 may just leak back out.
What if we could turn CO2 to stone, locking it away permanently? After all, under the right conditions this does happen naturally, just very slowly. For example, within common basalt rocks (which most of the of the ocean floor is made from) magnesium ions trigger the formation of calcite minerals from CO2 dissolved in water.
With this natural process in mind, back in 2007 an Icelandic project, dubbed CarbFix, started investigating whether mineralisation of CO2 could be a viable way to store carbon emissions captured from power stations. By 2012 they where ready to started pumping carbonic acid (CO2 dissolved in water) into the basalt rocks with the expectation that “if it’s mineralised within a human lifetime, then we know we are on a successful pathway”. After just 18 months, pumps inside the wells started to fail. When the pumps were retrieved, the team was surprised to find them caked with calcite crystals. Further investigations have shown that 95 per cent of the CO2 injected into the basalt had already been converted to stone. The mineralisation process that was expected to take decades (at best) seemed to be going on in just a matter of months.
These promising results were published earlier this summer in Science. The initial studies were on just 220 tonnes of CO2. However, CarbFix have already upscaled the project to sequester 10,000 tonnes of the gas per year within Icelandic rocks. This is still little compared to the 40 billions tonnes of CO2 emitted each year, but if the process can be proved to work in other locations then the ubiquitous nature of basalt rocks means there are plenty of potential sites to lock away our most damaging of pollutants.
Mark Lorch lectures in chemistry at Hull University