̽��ֱ�� of Cambridge - Massachusetts Institute of Technology

Steven Barrett appointed Regius Professor of Engineering

sc604 — Wed, 17 Apr 2024 18:48:18 +0000

Professor Steven Barrett has been appointed Regius Professor of Engineering at the ̽��ֱ�� of Cambridge, effective 1 June. He joins the ̽��ֱ�� from the Massachusetts Institute of Technology (MIT), where he is head of the Department of Aeronautics and Astronautics (AeroAstro).

Barrett’s appointment marks his return to Cambridge, where he was an undergraduate at Pembroke College, and received his PhD. He was a Lecturer in the Department of Engineering from 2008 until 2010, when he joined the faculty at MIT.

̽��ֱ��Regius Professorships are royal academic titles created by the monarch. ̽��ֱ��Regius Professorship in Engineering was announced in 2011, in honour of HRH Prince Philip, ̽��ֱ��Duke of Edinburgh’s 35 years as Chancellor of the ̽��ֱ��.

“It’s a pleasure to welcome Steven back to Cambridge to take up one of the ̽��ֱ��’s most prestigious roles,” said Vice-Chancellor Professor Deborah Prentice. “His work on sustainable aviation will build on Cambridge’s existing strengths, and will help us develop the solutions we need to address the threat posed by climate change.”

Barrett’s research focuses on the impact aviation has on the environment. He has developed a number of solutions to mitigate the impact aviation has on air quality, climate, and noise pollution. ̽��ֱ��overall goal of his research is to help develop technologies that eliminate the environmental impact of aviation. His work on the first-ever plane with no moving propulsion parts was named one of the 10 Breakthroughs of 2018 by Physics World.

“This is an exciting time to work on sustainable aviation, and Cambridge, as well as the UK more generally, is a wonderful platform to advance that,” said Barrett. “Cambridge’s multidisciplinary Department of Engineering, as well as the platform that the Regius Professorship provides, makes this a great opportunity. I’ve learned a lot at MIT, but I’d always hoped to come back to Cambridge at some point.”

Much of Barrett’s research focuses on the elimination of contrails, line-shaped clouds produced by aircraft engine exhaust in cold and humid conditions. Contrails cause half of all aviation-related global warming – more than the entirety of the UK economy. Barrett uses a combination of satellite observation and machine learning techniques to help determine whether avoiding certain regions of airspace could reduce or eliminate contrail formation.

“It will take several years to make this work, but if it does, it could drastically reduce emissions at a very low cost to the consumer,” said Barrett. “We could make the UK the first ‘Blue Skies’ country in the world – the first without any contrails in the sky.”

“Steven’s pioneering work on contrail formation and avoidance is a key element in reducing the environmental impact of aviation, and will strengthen the UK’s position as a world leader in this area,” said Professor Colm Durkan, Head of Cambridge’s Department of Engineering. “Together with Steven’s work on alternative aviation propulsion systems, this will strengthen Cambridge’s vision of helping us all achieve net zero at an accelerated rate.”

In addition to the Professorship in Engineering, there are seven other Regius Professorships at Cambridge: Divinity, Hebrew, Greek, Civil Law and Physic (all founded by Henry VIII in 1540), History (founded by George I in 1724) and Botany (founded in 2009, to mark the ̽��ֱ��’s 800th anniversary).

An expert on the environmental impacts of aviation, Barrett joins the ̽��ֱ�� of Cambridge from MIT.

It’s a pleasure to welcome Steven back to Cambridge to take up one of the ̽��ֱ��’s most prestigious roles

Vice-Chancellor Professor Deborah Prentice

MIT

Steven Barrett

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Hints of life discovered on Venus

sc604 — Mon, 14 Sep 2020 15:00:00 +0000

Astronomers have speculated for decades that high clouds on Venus could offer a home for microbes – floating free of the scorching surface, but tolerating very high acidity. ̽��ֱ��detection of phosphine molecules, which consist of hydrogen and phosphorus, is an important step in the search for life beyond Earth, a key question in science. ̽��ֱ��results are reported in the journal Nature Astronomy.

̽��ֱ��discovery was made by Professor Jane Greaves while she was a visitor at the ̽��ֱ�� of Cambridge’s Institute of Astronomy. Greaves and her collaborators used the James Clerk Maxwell Telescope (JCMT) in Hawaii to detect the phosphine, and followed up their discovery on the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. Both facilities observe Venus at a wavelength of about 1 millimetre, much longer than the human eye can see.

“This was an experiment made out of pure curiosity, really – taking advantage of JCMT’s powerful technology, and thinking about future instruments,” said Greaves, who is based at Cardiff ̽��ֱ��. “I thought we’d just be able to rule out extreme scenarios, like the clouds being stuffed full of organisms. When we got the first hints of phosphine in Venus’ spectrum, it was a shock!”

Luckily, conditions were good at ALMA for follow-up observations while Venus was at a suitable angle to Earth. Processing the data was challenging, however, as ALMA isn’t usually looking for subtle effects in bright objects like Venus.

“In the end, we found that both observatories had seen the same thing – faint absorption at the right wavelength to be phosphine gas, where the molecules are backlit by the warmer clouds below,” said Greaves.

Using existing models of the Venusian atmosphere to interpret the data, the researchers found that phosphine is present but scarce – only about twenty molecules in every billion. ̽��ֱ��astronomers then ran calculations to see if the phosphine could come from natural processes on Venus. They caution that some information is lacking – in fact, the only other study of phosphorus on Venus came from one lander experiment, carried by the Soviet Vega 2 mission in 1985.

On Earth, phosphine is only made industrially or by microbes that thrive in oxygen-free environments. Co-author Dr William Bains from MIT led the work on assessing natural ways to make phosphine on Venus. Ideas included sunlight, minerals blown upwards from the surface, volcanoes, or lightning, but none of these could make anywhere near enough. Natural sources were found to make at most one ten-thousandth of the amount of phosphine that the telescopes saw.

To create the observed quantity of phosphine on Venus, terrestrial organisms would only need to work at about 10% of their maximum productivity, according to calculations by co-author Dr Paul Rimmer of Cambridge’s Department of Earth Sciences. Any microbes on Venus will likely be very different from their Earth cousins though, to survive in hyper-acidic conditions.

“This discovery brings us right to the shores of the unknown,” said Rimmer, who is also affiliated with Cambridge's Cavendish Laboratory. “Phosphine is very hard to make in the oxygen-rich, hydrogen-poor clouds of Venus and fairly easy to destroy. ̽��ֱ��presence of life is the only known explanation for the amount of phosphine inferred by observations.

“Both of these facts lie at the edge of our knowledge: the observations could be caused by an unknown molecule, or could be caused by chemistry we’re not aware of. Ultimately, the only way to find out what's really happening is to send a mission into the clouds of Venus to take a sample of the droplets and look at them to see what's inside.”

Earth bacteria can absorb phosphate minerals, add hydrogen, and ultimately expel phosphine gas. It costs them energy to do this, so why they do it is not clear. ̽��ֱ��phosphine could be just a waste product, but other scientists have suggested purposes like warding off rival bacteria.

Co-author Dr Clara Sousa Silva from MIT was also thinking about searching for phosphine as a ‘biosignature’ gas of non-oxygen-using life on planets around other stars because normal chemistry makes so little of it. “Finding phosphine on Venus was an unexpected bonus,” she said. “ ̽��ֱ��discovery raises many questions, such as how any organisms could survive. On Earth, some microbes can cope with up to about 5% acid in their environment – but the clouds of Venus are almost entirely made of acid.”

Other possible biosignatures in the Solar System may exist, like methane on Mars and water venting from the icy moons Europa and Enceladus. On Venus, it has been suggested that dark streaks where ultraviolet light is absorbed could come from colonies of microbes. ̽��ֱ��Akatsuki spacecraft, launched by the Japanese space agency JAXA, is currently mapping these dark streaks to understand more about this unknown ultraviolet absorber.

̽��ֱ��team believes their discovery is significant because they can rule out many alternative ways to make phosphine, but they acknowledge that confirming the presence of ‘life’ needs a lot more work. Although the high clouds of Venus have temperatures up to a pleasant 30 degrees Celsius, they are incredibly acidic – around 90% sulphuric acid – posing major issues for microbes to survive there. ̽��ֱ��researchers are investigating the possibility that the microbes could shield themselves inside droplets.

̽��ֱ��team is now awaiting more telescope time to establish whether the phosphine is in a relatively temperate part of the clouds and to look for other gases associated with life. New space missions could also travel to our neighbouring planet, and sample the clouds to search for signs of life.

Professor Emma Bunce, President of the Royal Astronomical Society, said: “A key question in science is whether life exists beyond Earth, and the discovery by Professor Jane Greaves and her team is a key step forward in that quest. I’m particularly delighted to see UK scientists leading such an important breakthrough – something that makes a strong case for a return space mission to Venus.”

Reference:
Jane S. Greaves et al. ‘Phosphine Gas in the Cloud Decks of Venus.’ Nature Astronomy (2020). DOI: 10.1038/s41550-020-1174-4

Adapted from an RAS press release.

A UK-led team of astronomers has discovered a rare molecule – phosphine – in the clouds of Venus, pointing to the possibility of extra-terrestrial ‘aerial’ life.

̽��ֱ��presence of life is the only known explanation for the amount of phosphine inferred by observations

Paul Rimmer

JAXA / ISAS / Akatsuki Project Team

Synthesized false colour image of Venus

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

‘Quantum negativity’ can power ultra-precise measurements

sc604 — Wed, 29 Jul 2020 09:00:00 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, Harvard and MIT, have shown that quantum particles can carry an unlimited amount of information about things they have interacted with. ̽��ֱ��results, reported in the journal Nature Communications, could enable far more precise measurements and power new technologies, such as super-precise microscopes and quantum computers.

Metrology is the science of estimations and measurements. If you weighed yourself this morning, you’ve done metrology. In the same way as quantum computing is expected to revolutionise the way complicated calculations are done, quantum metrology, using the strange behaviour of subatomic particles, may revolutionise the way we measure things.

We are used to dealing with probabilities that range from 0% (never happens) to 100% (always happens). To explain results from the quantum world however, the concept of probability needs to be expanded to include a so-called quasi-probability, which can be negative. This quasi-probability allows quantum concepts such as Einstein’s ‘spooky action at a distance’ and wave-particle duality to be explained in an intuitive mathematical language. For example, the probability of an atom being at a certain position and travelling with a specific speed might be a negative number, such as –5%.

An experiment whose explanation requires negative probabilities is said to possess ‘quantum negativity.’ ̽��ֱ��scientists have now shown that this quantum negativity can help take more precise measurements.

All metrology needs probes, which can be simple scales or thermometers. In state-of-the-art metrology however, the probes are quantum particles, which can be controlled at the sub-atomic level. These quantum particles are made to interact with the thing being measured. Then the particles are analysed by a detection device.

In theory, the greater number of probing particles there are, the more information will be available to the detection device. But in practice, there is a cap on the rate at which detection devices can analyse particles. ̽��ֱ��same is true in everyday life: putting on sunglasses can filter out excess light and improve vision. But there is a limit to how much filtering can improve our vision — having sunglasses which are too dark is detrimental.

“We’ve adapted tools from standard information theory to quasi-probabilities and shown that filtering quantum particles can condense the information of a million particles into one,” said lead author Dr David Arvidsson-Shukur from Cambridge’s Cavendish Laboratory and Sarah Woodhead Fellow at Girton College. “That means that detection devices can operate at their ideal influx rate while receiving information corresponding to much higher rates. This is forbidden according to normal probability theory, but quantum negativity makes it possible.”

An experimental group at the ̽��ֱ�� of Toronto has already started building technology to use these new theoretical results. Their goal is to create a quantum device that uses single-photon laser light to provide incredibly precise measurements of optical components. Such measurements are crucial for creating advanced new technologies, such as photonic quantum computers.

“Our discovery opens up exciting new ways to use fundamental quantum phenomena in real-world applications,” said Arvidsson-Shukur.

Quantum metrology can improve measurements of things including distances, angles, temperatures and magnetic fields. These more precise measurements can lead to better and faster technologies, but also better resources to probe fundamental physics and improve our understanding of the universe. For example, many technologies rely on the precise alignment of components or the ability to sense small changes in electric or magnetic fields. Higher precision in aligning mirrors can allow for more precise microscopes or telescopes, and better ways of measuring the earth’s magnetic field can lead to better navigation tools.

Quantum metrology is currently used to enhance the precision of gravitational wave detection in the Nobel Prize-winning LIGO Hanford Observatory. But for the majority of applications, quantum metrology has been overly expensive and unachievable with current technology. ̽��ֱ��newly-published results offer a cheaper way of doing quantum metrology.

“Scientists often say that ‘there is no such thing as a free lunch’, meaning that you cannot gain anything if you are unwilling to pay the computational price,” said co-author Aleksander Lasek, a PhD candidate at the Cavendish Laboratory. “However, in quantum metrology this price can be made arbitrarily low. That’s highly counterintuitive, and truly amazing!”

Dr Nicole Yunger Halpern, co-author and ITAMP Postdoctoral Fellow at Harvard ̽��ֱ��, said: “Everyday multiplication commutes: Six times seven equals seven times six. Quantum theory involves multiplication that doesn’t commute. ̽��ֱ��lack of commutation lets us improve metrology using quantum physics.

“Quantum physics enhances metrology, computation, cryptography, and more; but proving rigorously that it does is difficult. We showed that quantum physics enables us to extract more information from experiments than we could with only classical physics. ̽��ֱ��key to the proof is a quantum version of probabilities — mathematical objects that resemble probabilities but can assume negative and non-real values.”

Reference:
David R. M. Arvidsson-Shukur et al. ‘Quantum advantage in postselected metrology.’ Nature Communications (2020). DOI: 10.1038/s41467-020-17559-w

Scientists have found that a physical property called ‘quantum negativity’ can be used to take more precise measurements of everything from molecular distances to gravitational waves.

We’ve shown that filtering quantum particles can condense the information of a million particles into one

David Arvidsson-Shukur

Hugo Lepage

Artist's impression of a quantum metrology device

Yes

Defects in next-generation solar cells can be healed with light

sc604 — Wed, 06 Sep 2017 15:48:00 +0000

̽��ֱ��international team of researchers demonstrated in 2016 that defects in the crystalline structure of perovskites could be healed by exposing them to light, but the effects were temporary.

Now, an expanded team, from Cambridge, MIT, Oxford, Bath and Delft, have shown that these defects can be permanently healed, which could further accelerate the development of cheap, high-performance perovskite-based solar cells that rival the efficiency of silicon. Their results are reported in the inaugural edition of the journal Joule, published by Cell Press.

Most solar cells on the market today are silicon-based, but since they are expensive and energy-intensive to produce, researchers have been searching for alternative materials for solar cells and other photovoltaics. Perovskites are perhaps the most promising of these alternatives: they are cheap and easy to produce, and in just a few short years of development, perovskites have become almost as efficient as silicon at converting sunlight into electricity.

Despite the potential of perovskites, some limitations have hampered their efficiency and consistency. Tiny defects in the crystalline structure of perovskites, called traps, can cause electrons to get “stuck” before their energy can be harnessed. ̽��ֱ��easier that electrons can move around in a solar cell material, the more efficient that material will be at converting photons, particles of light, into electricity.

“In perovskite solar cells and LEDs, you tend to lose a lot of efficiency through defects,” said Dr Sam Stranks, who led the research while he was a Marie Curie Fellow jointly at MIT and Cambridge. “We want to know the origins of the defects so that we can eliminate them and make perovskites more efficient.”

In a 2016 paper, Stranks and his colleagues found that when perovskites were exposed to illumination, iodide ions – atoms stripped of an electron so that they carry an electric charge – migrated away from the illuminated region, and in the process swept away most of the defects in that region along with them. However, these effects, while promising, were temporary because the ions migrated back to similar positions when the light was removed.

In the new study, the team made a perovskite-based device, printed using techniques compatible with scalable roll-to-roll processes, but before the device was completed, they exposed it to light, oxygen and humidity. Perovskites often start to degrade when exposed to humidity, but the team found that when humidity levels were between 40 and 50 percent, and the exposure was limited to 30 minutes, degradation did not occur. Once the exposure was complete, the remaining layers were deposited to finish the device.

When the light was applied, electrons bound with oxygen, forming a superoxide that could very effectively bind to electron traps and prevent these traps from hindering electrons. In the accompanying presence of water, the perovskite surface also gets converted to a protective shell. ̽��ֱ��shell coating removes traps from the surfaces but also locks in the superoxide, meaning that the performance improvements in the perovskites are now long-lived.

“It’s counter-intuitive, but applying humidity and light makes the perovskite solar cells more luminescent, a property which is extremely important if you want efficient solar cells,” said Stranks, who is now based at Cambridge’s Cavendish Laboratory. “We’ve seen an increase in luminescence efficiency from one percent to 89 percent, and we think we could get it all the way to 100 percent, which means we could have no voltage loss – but there’s still a lot of work to be done.”

̽��ֱ��research was funded by the European Union, the National Science Foundation, and the Engineering and Physical Sciences Research Council.

Reference:
Roberto Brenes et al. ‘Metal Halide Perovskite Polycrystalline Films Exhibiting Properties of Single Crystals.’ Joule (2017). DOI: 10.1016/j.joule.2017.08.006

Researchers have shown that defects in the molecular structure of perovskites – a material which could revolutionise the solar cell industry – can be “healed” by exposing it to light and just the right amount of humidity.

We want to know the origins of the defects so that we can eliminate them and make perovskites more efficient.

Sam Stranks

Dr Matthew T Klug

' ̽��ֱ��concoction of light with water and oxygen molecules leads to substantial defect-healing in metal halide perovskite semiconductors

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Cambridge to host transatlantic cyber security competition

Anonymous — Thu, 20 Jul 2017 08:55:49 +0000

̽��ֱ��“Cambridge2Cambridge” cyber security competition, backed by government and industry, is the brainchild of the ̽��ֱ�� of Cambridge and the Massachusetts Institute of Technology (MIT) in the US, and will see talented students pitted against each other in a three-day showdown.

In total, 110 students from 25 universities from the UK and USA will form mixed transatlantic teams and battle against a fictional rogue state in the life-like cyber security competition backed by the National Cyber Security Centre (NCSC) and Cabinet Office.

̽��ֱ��annual event is now in its second year with prize money up for grabs for the winners. It will be held from 24-26 July at Trinity College, Cambridge.

With major cyber-attacks on the increase, according to the NCSC, the need for cyber security experts is more important than ever before.

Professor Frank Stajano, Head of the Academic Centre of Excellence in Cyber Security Research at Cambridge’s Computer Laboratory and the co-founder of Cambridge2Cambridge, said that the competition has been designed to promote greater cyber security collaboration between the UK and USA, and to give students the platform to explore creative ways to combat global cyber-attacks.

“ ̽��ֱ��aim of the competition is also to bring together different individuals in a fun and inclusive environment, where they can apply their cyber security abilities in a collaborative and competitive setting, allowing students to implement the skills they have been taught, while learning new ones in the process,” he said.

It also gives budding cyber enthusiasts the opportunity to meet like-minded individuals, and learn more about careers in the sector by introducing them to key players in the industry and government.

https://cambridge2cambridge.csail.mit.edu/

A major cyber security challenge, aimed at educating and inspiring the next generation of cyber defenders from across the UK and US, will be held at the ̽��ֱ�� of Cambridge next week.

̽��ֱ��aim of the competition is to bring together different individuals in a fun and inclusive environment, where they can apply their cyber security abilities in a collaborative and competitive setting.

Frank Stajano

Inter-ACE Cyber Challenge 2017

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Non-toxic alternative for next-generation solar cells

sc604 — Tue, 18 Jul 2017 09:00:50 +0000

̽��ֱ��team of researchers, from the ̽��ֱ�� of Cambridge and the United States, have used theoretical and experimental methods to show how bismuth – the so-called “green element” which sits next to lead on the periodic table, could be used in low-cost solar cells. Their results, reported in the journal Advanced Materials, suggest that solar cells incorporating bismuth can replicate the properties that enable the exceptional properties of lead-based solar cells, but without the same toxicity concerns. Later calculations by another research group showed that bismuth-based cells can convert light into energy at efficiencies up to 22%, which is comparable to the most advanced solar cells currently on the market.

Most of the solar cells which we see covering fields and rooftops are made from silicon. Although silicon is highly efficient at converting light into energy, it has a very low “defect tolerance”, meaning that the silicon needs to have very high levels of purity, making it energy-intensive to produce.

Over the past several years, researchers have been looking for materials which can perform at similar or better levels to silicon, but that don’t need such high purity levels, making them cheaper to produce. ̽��ֱ��most promising group of these new materials are called hybrid lead halide perovskites, which appear to promise a revolution in the field of solar energy.

As well as being cheap and easy to produce, perovskite solar cells have, in the space of a few years, become almost as energy-efficient as silicon. However, despite their enormous potential, perovskite solar cells are also somewhat controversial within the scientific community, since lead is integral to their chemical structure. Whether the lead contained within perovskite solar cells represents a tangible risk to humans, animals and the environment is being debated, however, some scientists are now searching for non-toxic materials which could replace the lead in perovskite solar cells without negatively affecting performance.

“We wanted to find out why defects don’t appear to affect the performance of lead-halide perovskite solar cells as much as they would in other materials,” said Dr Robert Hoye of Cambridge’s Cavendish Laboratory and Department of Materials Science & Metallurgy, and the paper’s lead author. “If we can figure out what’s special about them, then perhaps we can replicate their properties using non-toxic materials.”

In collaboration with colleagues at MIT, the National Renewable Energy Laboratory and Colorado School of Mines in the US, the Cambridge researchers have shown that bismuth, which sits next to lead in the periodic table, could be a non-toxic alternative to lead for use in next-generation solar cells. Bismuth, known as the “green element”, is widely used in cosmetics, personal care products and medicines. Like lead, it is a heavy metal, but it is non-toxic.

For this study, Hoye and his colleagues looked at bismuth oxyiodide, a material which was previously investigated for use in solar cells and water splitting, but was not thought to be suitable because of low efficiencies and because it degraded in liquid electrolytes. ̽��ֱ��researchers used theoretical and experimental methods to revisit this material for possible use in solid-state solar cells.

They found that bismuth oxyiodide is as tolerant to defects as lead halide perovskites. Bismuth oxyiodide is also stable in air for at least 197 days, which is a significant improvement over some lead halide perovskite compounds. By sandwiching the bismuth oxyiodide light absorber between two oxide electrodes, they were able to demonstrate a record performance, with the device converting 80% of light to electrical charge.

̽��ֱ��bismuth-based devices can be made using common industrial techniques, suggesting that they can be produced at scale and at low cost.

“Bismuth oxyiodide has all the right physical property attributes for new, highly efficient light absorbers,” said co-author Professor Judith Driscoll, of the Department of Materials Science and Metallurgy. “I first thought of this compound around five years ago, but it took the highly specialised experimental and theoretical skills of a large team for us to prove that this material has real practical potential.”

“This work shows that earlier theories about bismuth oxyiodide were not wrong, and these compounds do have the potential to be successful solar cells,” said Hoye, who is a Junior Research Fellow at Magdalene College. “We’re just scratching the surface of what these compounds can do.”

“Previously, the global solar cell research community has been searching for non-toxic materials that replicate the defect tolerance of the perovskites, but without much success in terms of photovoltaic performance,” said Dr David Scanlon, a theorist at UCL not involved in this work. “When I saw this work, my team calculated based on the optical properties that bismuth oxyiodide has a theoretical limit of 22% efficiency, which is comparable to silicon and the best perovskite solar cells. There’s a lot more we could get from this material by building off this team’s work.”

Reference
Robert Hoye et al. ‘Strongly Enhanced Photovoltaic Performance and Defect Physics of Air-Stable Bismuth Oxyiodide (BiOI).’ Advanced Materials (2017). DOI: 10.1002/adma.201702176

Researchers have demonstrated how a non-toxic alternative to lead could form the basis of next-generation solar cells.

We’re just scratching the surface of what these compounds can do.

Robert Hoye

Steve Penney

Bismuth oxyiodide light absorbers

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

First atmospheric study of Earth-sized exoplanets using Hubble telescope

sjr81 — Wed, 20 Jul 2016 17:15:38 +0000

Embarking on the first attempt at detecting the atmospheres of planets outside our solar system, a team of Cambridge and international researchers discovered that the exoplanets TRAPPIST-1b and TRAPPIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres such as those usually found on gaseous worlds like Jupiter or Saturn.

̽��ֱ��lack of a hydrogen-helium envelope increases the Earth-likeliness of these planets and has caused considerable excitement among researchers taking part in the study. ̽��ֱ��results of their findings are published today in the journal Nature.

“Humanity’s remote exploration of alien environments has truly started,” said Amaury Triaud, a research fellow at Cambridge’s Institute of Astronomy. “It is tantalizing to think that with another ten similar observations, we would start distinguishing whether those planets are more Venus-like, more Earth-like, or if they are radically different.”

Researchers observed the planets in near-infrared light and used spectroscopy to decode a change of light as the planets transited in front of their stars. During transit, starlight shines through a planet’s atmosphere making it possible to deduce its chemical makeup.

Both planets orbit TRAPPIST-1 – an ultracool dwarf star that is much cooler and redder than the sun, and barely larger than Jupiter. TRAPPIST-1 has a mass 8% that of the Sun and is located in the constellation of Aquarius. ̽��ֱ��planets orbiting the star were discovered in late 2015 through a series of observations by the TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST), a Belgian robotic telescope located at ESO’s (European Southern Observatory’s) La Silla Observatory in Chile. ̽��ֱ��small size of the star TRAPPIST-1 boosts the signal produced by the planets’ atmospheres, easing their study by nearly 100 times compared to similar planets orbiting stars like the Sun.

TRAPPIST-1b completes a circuit around its red dwarf star in 1.5 days and TRAPPIST-1c in 2.4 days. Thanks to the faintness of the star they orbit, and to the planet’s short orbits, it is possible that parts of their surfaces have temperatures similar to the Earth. While it remains unclear whether the planets are habitable, they are the first worlds for which we can determine the existence of a habitable climate.

On May 4, astronomers took advantage of a rare simultaneous transit, when both planets crossed the face of their star within minutes of each other, to measure starlight as it filtered through any existing atmosphere. This double transit, which occurs only once every two years, provided a chance to hasten the atmospheric study of TRAPPIST-1b and TRAPPIST-1c.

̽��ֱ��researchers now hope to use Hubble to conduct follow-up observations to search for thinner atmospheres, composed of elements heavier than hydrogen, like those of Earth and Venus.

Observations from future telescopes, including NASA’s James Webb Space Telescope, will help determine the full composition of these atmospheres and hunt for potential biosignatures, such as carbon dioxide and ozone, in addition to water vapor and methane. Webb also will analyze a planet’s temperature and surface pressure – key factors in assessing its habitability.

“Our observations demonstrate that Hubble has the capacity to play a central role,” said lead researcher Julien de Wit, of the Massachusetts Institute of Technology. “It can carry-out an atmospheric pre-screening, to tell astronomers which of these Earth-sized planets are prime candidates for more detailed study with the Webb telescope.”

̽��ֱ��TRAPPIST telescope identified these two Earth-sized worlds during a prototype run for a more ambitious venture, called SPECULOOS, which is currently in construction at Cerro Paranal, Chile. SPECULOOS will monitor 1,000 nearby red dwarf stars seeking additional Earth-sized worlds.

Professor Didier Queloz, Professor of Physics at the Cavendish Laboratory, and a founding member of the project, said: “Within the next five years, SPECULOOS will likely detect 20-30 new Earth-sized planets. All of them will have atmospheres that can be investigated by the James Webb.”

Dr Brice-Olivier Demory, a senior research associate at the Cavendish Laboratory, said: “Soon we will have the right targets, and the right telescopes to start investigating rocky planet atmospheres beyond our Solar system. Finding out whether other worlds are indeed Earth-like is only a matter of time.”

̽��ֱ��Hubble Space Telescope is a project of international cooperation between NASA and ESA. Goddard manages the telescope and STScI conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington.

Two Earth-sized exoplanets have become the first rocky worlds to have their atmospheres studied using the Hubble Space Telescope.

Humanity’s remote exploration of alien environments has truly started.

Amaury Triaud

NASA

Artist's View of Planets Transiting Red Dwarf Star in TRAPPIST-1 System

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Licence type:

Attribution-Noncommercial-ShareAlike

Bacteria in the world’s oceans produce millions of tonnes of hydrocarbons each year

sc604 — Mon, 05 Oct 2015 19:00:00 +0000

An international team of researchers, led by the ̽��ֱ�� of Cambridge, has estimated the amount of hydrocarbons – the primary ingredient in crude oil – that are produced by a massive population of photosynthetic marine microbes, called cyanobacteria. These organisms in turn support another population of bacteria that ‘feed’ on these compounds.

In the study, conducted in collaboration with researchers from the ̽��ֱ�� of Warwick and MIT, and published today (5 October) in the journal Proceedings of the National Academy of Sciences of the USA, the scientists measured the amount of hydrocarbons in a range of laboratory-grown cyanobacteria and used the data to estimate the amount produced in the oceans.

Although each individual cell contains minuscule quantities of hydrocarbons, the researchers estimated that the amount produced by two of the most abundant cyanobacteria in the world – Prochlorococcus and Synechococcus – is more than two million tonnes in the ocean at any one time. This indicates that these two groups alone produce between 300 and 800 million tonnes of hydrocarbons per year, yet the concentration at any time in unpolluted areas of the oceans is tiny, thanks to other bacteria that break down the hydrocarbons as they are produced.

“Hydrocarbons are ubiquitous in the oceans, even in areas with minimal crude oil pollution, but what hadn’t been recognised until now is the likely quantity produced continually by living oceanic organisms,” said Professor Christopher Howe from Cambridge’s Department of Biochemistry, the paper’s senior author. “Based on our laboratory studies, we believe that at least two groups of cyanobacteria are responsible for the production of massive amounts of hydrocarbons, and this supports other bacteria that break down the hydrocarbons as they are produced.”

̽��ֱ��scientists argue that the cyanobacteria are key players in an important biogeochemical cycle, which they refer to as the short-term hydrocarbon cycle. ̽��ֱ��study suggests that the amount of hydrocarbons produced by cyanobacteria dwarfs the amount of crude oil released into the seas by natural seepage or accidental oil spills.

However, the hydrocarbons produced by cyanobacteria are continually broken down by other bacteria, keeping the overall concentrations low. When an event such as an oil spill occurs, hydrocarbon-degrading bacteria are known to spring into action, with their numbers rapidly expanding, fuelled by the sudden local increase in their primary source of energy.

̽��ֱ��researchers caution that their results do not in any way diminish the enormous harm caused by oil spills. Although some microorganisms are known to break down hydrocarbons in oil spills, they cannot repair the damage done to marine life, seabirds and coastal ecosystems.

“Oil spills cause widespread damage, but some parts of the marine environment recover faster than others,” said Dr David Lea-Smith, a postdoctoral researcher in the Department of Biochemistry, and the paper’s lead author. “This cycle is like an insurance policy – the hydrocarbon-producing and hydrocarbon-degrading bacteria exist in equilibrium with each other, and the latter multiply if and when an oil spill happens. However, these bacteria cannot reverse the damage to ecosystems which oil spills cause.”

̽��ֱ��researchers stress the need to test if their findings are supported by direct measurements on cyanobacteria growing in the oceans. They are also interested in the possibility of harnessing the hydrocarbon production potential of cyanobacteria industrially as a possible source of fuel in the future, although such work is at a very early stage.

Reference:
Lea-Smith, D. et. al. “Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle.” PNAS (2015). DOI: 10.1073/pnas.1507274112

Scientists have calculated that millions of tonnes of hydrocarbons are produced annually by photosynthetic bacteria in the world’s oceans.

This cycle is like an insurance policy – the hydrocarbon-producing and hydrocarbon-degrading bacteria exist in equilibrium with each other

David Lea-Smith

Image courtesy SeaWiFS Project

Global chlorophyll

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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