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Energy efficiency symposium - new attendees welcome

Physics of Sustainability

The inaugural, one-day Winton Symposium on energy efficiency will be held on Monday, 1 October 2012 at the Cavendish Laboratory. The event will bring together some of the leading scientists from around the world to explore the fundamental limits set by science and engineering to the efficiency with which we can generate, store and use energy.

This is the first of an annual series of topical meetings as part of the Winton Programme for the Physics of Sustainability.

There is no registration fee for the Symposium and complimentary lunch will be provided.  However, participants are required for register online for the event.

To set the scene of the symposium, Malcolm Keay from the Oxford Institute for Energy Studies will discuss the link between energy efficiency and sustainability.  This will be followed by three sessions.

Man versus Machine

Energy consumption for computing is growing rapidly, Prof. Eli Yablonovitch, Director of the NSF Center for Energy Efficient Electronics Science at University of California Berkeley and Prof. Stuart Parkin from IBM's Almaden Research Center will explore the trends and efficiency limits for computation and data storage respectively. Prof. Simon Laughlin Professor of Neurobiology at the department of Zoology in Cambridge will explain why the brain, in contrast, is so efficient at computation.

Energy Generation from the Sun

The sun is our primary source of energy, Prof. Jenny Nelson from Imperial College will explain the limits for solar cell technologies and Prof. Richard Cogdell, Director of the Glasgow Biomedical Research Centre will explore what we can learn from light harvesting in nature.

Energy Usage

Energy usage will be discussed in the context of two major consumers of power, transportation and lighting. Dr. Donald Hillebrand, Director of the Center for Transportation Research, Argonne National Laboratory will cover conventional and electric vehicle technologies and their relative efficiencies. Prof. James Speck from University of California Santa Barbara will review advances and fundamental efficiency limits for solid-state lighting.

For free registration - http://www.phy.cam.ac.uk/conferences/energyefficiency/form/booking.php

For more information, please follow the link on the upper right hand side.




Inaugural event will explore some of the latest in energy research.

Winton Symposium on energy efficiency will be held on Monday, 1 October 2012 at the Cavendish Laboratory.
Physics of Sustainability

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Scientists create artificial mother of pearl

Mother of pearl next to artificial nacre

Mimicking the way mother of pearl is created in nature, scientists have for the first time synthesised the strong, iridescent coating found on the inside of some molluscs.  The research was published today in the journal Nature Communications.

Nacre, also called mother of pearl, is the iridescent coating that is found on the inside of some molluscs and on the outer coating of pearls.  By recreating the biological steps that form nacre in molluscs, the scientists were able to manufacture a material which has a similar structure, mechanical behaviour, and optical appearance of that found in nature.

In order to create the artificial nacre, the scientists followed three steps.  First, they had to take preventative measure to ensure the calcium carbonate, which is the primary component of nacre, does not crystallise when precipitating from the solution.  This is done by using a mixture of ions and organic components in the solution that mimics how molluscs control this. The precipitate can then be adsorbed to surfaces, forming layers of well-defined thickness.

Next, the precipitate layer is covered by an organic layer that has 10-nm wide pores, which is done in a synthetic procedure invented by co-author Alex Finnemore. Finally, crystallisation is induced, and all steps are repeated to create a stack of alternating crystalline and organic layers.

Professor Ulli Steiner, of the Department of Physics’ Cavendish Laboratory at the University of Cambridge, said: “Crystals have a characteristic shape that reflects their atomic structure, and it is very difficult to modify this shape.  Nature is, however, able to do this, and through our research we were able to gain insight into how it grows these materials.  Essentially, we have created a new recipe for mother of pearl using nature’s cookbook.”

Alex Finnemore, also of the Department of Physics’ Cavendish Laboratory, said: “While many composite engineering materials outperform nacre, its synthesis entirely at ambient temperatures in an aqueous environment, as well as its cheap ingredients, may make it interesting for coating applications. Once optimised, the process is simple and can easily be automated.”

Research paves way for tough coatings fabricated from cheap, abundant materials.

Essentially, we have created a new recipe for mother of pearl using nature’s cookbook.
Professor Ulli Steiner, of the Department of Physics’ Cavendish Laboratory
Mother of pearl next to artificial nacre

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Study to reduce radiotherapy toxicity

Radiotherapy treatment plan for a head and neck tumour showing colour-shaded dosage areas.

About half of all people with cancer receive a course of radiotherapy, a form of treatment in which X-rays are used to shrink or destroy the tumour. With the benefit of advanced systems, it is now possible to aim radiation beams at tumours more effectively than ever before, allowing increasing doses of radiotherapy with increased cancer cure rates, and also reducing side effects.

However, although clinicians use planning software to define the target area for treatment and deliver the optimal dose, any dose that falls outside the target area – for instance due to the positioning of the patient and their internal organs during treatment – can cause permanent and severe damage to normal tissues.

Now, a new research programme at the University of Cambridge aims to reduce levels of toxicity from radiotherapy, enabling doses of the treatment to be escalated. By examining to what extent the dose of radiation planned by the clinician for a patient differs from that which the patient actually receives – and how this damages normal, healthy tissues – the programme will develop a set of tools that can be used to provide patients with the optimal dosage for their condition.

“We are breaking new ground thanks to the marshalling of forces from several fields,” said Professor Neil Burnet, who leads the research. Expertise is being pooled from a cross-disciplinary group of clinicians and scientists from the University of Cambridge Departments of Oncology, Physics, Engineering, and Applied Mathematics and Theoretical Physics, the NHS Oncology Centre, and the Cancer Research UK (CRUK) Cambridge Research Institute.

“The aim will always be to safely deliver radiation to the tumour and so kill the cancerous cells,” he added. “Although modern technology has improved side effects, 29% of patients are still left with significant dry mouth after head and neck radiotherapy because of damage to the salivary glands, and 10% of men experience severe toxicity after prostate radiotherapy because of rectal damage. Hormonal dysfunction after radiotherapy damage to the hypothalamus and pituitary gland can result in a patient needing lifelong hormone replacement therapy.”

The VoxTox Research Programme, a five-year study funded by CRUK, focuses on reducing radiation toxicity. After quantifying the differences between planned dose and the dose actually delivered during the whole course of radiotherapy, the programme will link these data to differences between expected and observed toxicity. It will look into the physical factors behind dose variation such as movement of internal organs, as well as suspected biological factors, such as a patient’s genetic make-up.

“In Cambridge there is a unique archive of daily computed tomography (CT) scans – imaging data acquired during the course of a patient’s high-precision image-guided radiotherapy on our TomoTherapy treatment machines,” said Burnet. “Systems will be developed to map the location of each point, or voxel, within the patient outline, and then to re-compute the dose at that point each day during treatment.”

The study will develop a suite of integrated software tools for dose review during the treatment course, with the objective of individualising treatment based on predicted toxicity, and make these tools available to the world cancer community.

For more information, please visit www.voxtox.org, where readers can sign up for email updates on the Programme, or contact the VoxTox Research Programme Co-ordinator Michael Simmons (mps48@cam.ac.uk).

A new research programme at the University of Cambridge hopes to improve cancer cure rates by reducing toxicity from radiotherapy.

We are breaking new ground thanks to the marshalling of forces from several fields.
Neil Burnet
Radiotherapy treatment plan for a head and neck tumour showing colour-shaded dosage areas.

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Cambridge extends MIT exchange partnership

Andy Leonard, Vice President BP Cambridge, with some of the first BP supported Cambridge-MIT exchange students at the launch of the extension of the programme to non-Engineers from Cambridge University.

Originally set up in 2000, the Cambridge-MIT exchange programme has to date enabled more than 300 Cambridge students to benefit from a chance to study in the United States as part of their undergraduate course. In the last two academic years, generous funding from BP has allowed more than 30 students, most of them from the Department of Engineering, to take part.

Now, BP has given further funding to the University which will enable more students to participate. The arrangements, which were announced at a launch event last night, will mean that places are open to students from Chemical Engineering, Chemistry, Computer Sciences, Mathematics and Physics as well. In total a further 18 places on the programme will be funded over the course of the next three years.

Those who have been on the exchange have typically found it a life-changing experience. One graduate reported back: “My year at MIT was long, challenging and full of by far the most rewarding experiences of my life. From the range of fascinating and varied courses I took to the unbelievable friends I made, every aspect of the exchange scored a massive success. If I had to pick one standout feature, it would be that as a structural engineer I really appreciated the chance to interact intimately with other disciplines in cross-over classes at both MIT and Harvard.”

Another wrote: “The experience taught me not only the joy of teamwork, but also gave me a chance to meet engineers from across the US, and beyond.”

Dr Peter Long, from the University’s Department of Engineering, said: “The students who have been on this exchange have all benefited greatly from the adventure, often returning to lead new University activities and going on to flourish in industry and research.”

“The extension of the scope of the programme beyond the Engineering core  will strengthen the exchange and further enable students to take advantage of the breath of subjects in the two Universities. We hope that this is just a sign of things to come and that in the future it will be possible to extend the exchange programme again, taking it beyond the physical sciences.”

An extension to the University of Cambridge’s exchange programme with the Massachusetts Institute of Technology has been announced, enabling more undergraduates to study at “both” Cambridges during their degree.

The students who have been on this exchange have all benefited greatly from the adventure, often returning to lead new University activities and going on to flourish in industry and research.
Peter Long
Andy Leonard, Vice President BP Cambridge, with some of the first BP supported Cambridge-MIT exchange students at the launch of the extension of the programme to non-Engineers from Cambridge University.

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Opening new windows on the Universe

Dust ring around the star Fomalhaut taken by ALMA

How do planetary systems form? What do the surfaces of stars look like? Does life exist elsewhere in the Universe? Astronomers have developed many theoretical models, but until now the ability to validate these with observations has been severely constrained by the telescope capabilities available.

Taking the lead in three major new international projects, Cambridge astronomers are tackling the enormous technical challenges involved in developing bigger and better telescopes to open new windows onto the Universe. Building on Cambridge’s strong legacy of achievement in astronomical instrumentation, the new telescopes all utilise one important underlying technique –interferometry by aperture synthesis – to probe the Universe at a level of detail far beyond the capabilities of any telescope currently in existence. Each telescope will detect light at a different wavelength and help to build a fuller picture of exactly what is out there.

Filling in the detail

“When we look at regions of star formation with the best existing high-frequency radio telescope, we see blobs. We can learn a lot by looking at the radio waves that come out of these, but inside there will be all sorts of complicated structures that the telescope can’t resolve,” said Dr John Richer, astrophysicist at the Cavendish Laboratory and the Kavli Institute for Cosmology.

Richer is UK Project Scientist for the Atacama Large Millimetre Array (ALMA), a partnership project involving Europe, North America, East Asia and the Republic of Chile. Currently under construction in Chile, this revolutionary sub-millimetre radio telescope will consist of 66 high-precision antennas working in perfect synchrony when fully operational in 2013.

Interferometry will be used to combine the information they collect, ‘synthesising’ an aperture with an effective diameter of 16 km to create an ultra-high-resolution telescope. Professor Richard Hills, who is currently on secondment in Chile, designed the set of radio receivers that calibrate the telescope and are central to ALMA achieving its scientific goals, and Richer’s team is developing the software to correct the images from ALMA.

“ALMA is an incredible piece of engineering that will enable us to zoom in to take pictures with a thousand times better resolution than we can now, so we’ll actually see all the detailed structure instead of blobs,” said Richer. “We’re hoping to unlock the secret of how planetary systems form, and to look back in time at the very early Universe.”

With 33 of the antennas currently operational, the telescope is already returning stunning images. “The whole astronomical community wants to use ALMA because it’s unique, and a huge breakthrough in capabilities,” said Richer. “There’s an unprecedented level of oversubscription, because nearly everything in the Universe has some emission at these radio wavelengths that is interesting and not well understood.”

Building a fuller picture

Dr David Buscher and Professor Chris Haniff, astrophysicists at the Cavendish Laboratory, are system architects for the Magdalena Ridge Observatory Interferometer (MROI), a collaborative project with New Mexico Tech, USA, that also uses interferometry, but this time at visible wavelengths.

“Optical interferometry provides information not available from conventional optical telescopes or from radio interferometers,” said Buscher. “Both radio and optical interferometers can see fine detail: putting together this detail allows us to answer new questions.”

The pair started with a set of high-level scientific questions, drawn up by a consortium of UK astrophysicists, and used these to specify a new high-precision optical array. “The great thing about this project is that we’ve been able to design and build, from scratch, an instrument to answer fundamental scientific questions that cannot be answered in any other way,” said Buscher. Haniff added: “We are involved in all the major design questions, from what size telescopes are the best, to how many, to which configuration would produce the best images, and we’re developing the software that will make images from the data.”

When constructed on its mountain-top site in New Mexico, the MROI will be the lead instrument in its field, consisting of 10 telescopes that will produce images with 100 times the resolution of those from the Hubble Space Telescope. By looking at external galaxies, it is expected to revolutionise understanding of astrophysical phenomena ranging from active galactic nuclei to black holes. Closer to Earth, it will help answer questions about the formation of stars and planets.

“There are models for what’s going on,” said Haniff, “but these could be completely wrong – at the moment the detail is far too fine to see. By using interferometry to simulate the resolving power of a single optical telescope of up to 340 m in diameter, the MROI will enable us to see structures that are so small they couldn’t otherwise be detected at visible wavelengths.” The advanced technology of the MROI could also have important commercial applications, such as in taking images of broken telecommunications satellites in geostationary orbit to help diagnose what has gone wrong.

Signs of life?

The third telescope in the trio, the Square Kilometer Array (SKA), will be the largest and most sensitive radio telescope ever, and its design involves astronomers, engineers and industry partners from 20 countries. Professor Paul Alexander, Head of Astrophysics at the Cavendish Laboratory, is playing a leading role in its development. Involving a ‘sea’ of antennas – over half a million in the first phase – acting as one enormous interferometer covering 1 km2, the concept calls for a very simple design with low unit cost. “At the moment we’re working very closely with our industrial partner, Cambridge Consultants, on the detailed design,” he said. “It’s also going to be a major computing challenge – the data transport from the dishes will produce 10 times the current global internet traffic.”

With one of its design goals being “to maximise the ability to explore the unknown”, SKA will enable astronomers to see incredibly faint signals. “With SKA we will be able to look back to the time when the first objects formed in the Universe, and try to understand how we got from there to what we have now,” explained Alexander. “A second experiment will use pulsars, originally discovered by Antony Hewish and Jocelyn Bell-Burnell in Cambridge, as extremely accurate natural clocks. Finding a pulsar in orbit around a black hole will enable us to properly test Einstein’s gravitational theory.”

This extremely powerful telescope also provides an exciting new approach to the search for extra-terrestrial intelligence (SETI). “The trouble with most SETI searches is that they rely on someone communicating with you just at the time when you’re listening,” said Alexander. “SKA is so much more sensitive than anything we’ve had before. We’ll be able to look for evidence of unintentional radio emissions, the equivalent of airport radar, from our nearby stars and planetary systems that may indicate intelligent life.”

Although work on SKA has already begun, construction will not start until 2016 and the telescope will not be fully operational until 2024. Development work for all three telescopes extends back decades, as Alexander explained: “We’re building on our legacy”. The idea for interferometry was originally conceived in the 1880s, but it wasn’t until the 1950s that it was developed and used at radio wavelengths – a technique for which Cambridge astronomers Martin Ryle and Antony Hewish won a Nobel Prize in 1974. It was also in Cambridge in the 1980s that reliable interferometric imaging was first shown to be feasible at optical wavelengths, and this paved the way for building the MROI.

A challenge of many disciplines

“To build these big telescopes you need teams of people with expertise across astronomy, technology and computing,” explained Alexander. “You’ve got to pull everyone together to do good, competitive science”. Recognising this, the University plans to build a new Centre for Experimental Astrophysics to enable greater integration of its strengths. Construction of the Centre will begin this October on a site adjacent to the University’s Kavli Institute, thanks to generous philanthropic support from Cavendish Alumnus Mr Humphrey Battcock and The Wolfson Foundation. “The new building will enable us to create the teams needed to take on these big scientific challenges, which will lead to major advances in our knowledge and understanding of the Universe,” said Alexander.

Advances in telescope technology being developed at Cambridge will drive a revolutionary period of discovery in astronomy.

We’ll be able to look for evidence of unintentional radio emissions, the equivalent of airport radar, from our nearby stars and planetary systems that may indicate intelligent life.
Dust ring around the star Fomalhaut taken by ALMA

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World-renowned astrophysicist to join Cavendish Laboratory

This artist's impression shows a gas-giant exoplanet transiting across the face of its star. Infrared analysis by NASA's Spitzer Space Telescope.

One of Europe’s top experts on exoplanets, planets located beyond the Solar System, will be joining the University’s Department of Physics.  The world-leading astrophysicist Professor Didier Queloz has been appointed to the post of Professor of Physics at the Cavendish Laboratory.

Professor Queloz said: "I am delighted to be moving to Cambridge. It is a real honour for me to join a University which has been the home and source of inspiration to so many great scientists."

Extra-solar system planets, or exoplanets, were first detected by Queloz and his colleague Michel Mayor in 1995.  Since then, more than 800 exoplanets have been discovered.

Professor James Stirling, Head of the Department of Physics, said: "We are delighted that Didier will be joining us as a Professor in the Cavendish Laboratory next year. We have made a very considerable investment in experimental astrophysics in recent years, including a brand new building to house our astrophysics group.  Didier's appointment will open up a new strand of research in one of the most exciting areas of modern astronomy and will build upon the expertise we already have in instrument development, star and planet formation, atmospheric chemistry, planetary geophysics and climatology.

“It will also further cement links with our colleagues in the Institute of Astronomy and the Department of Applied Mathematics and Theoretical Physics, and help maintain Cambridge and UK leadership in fundamental science."

The study of exoplanets is a relatively new field of astrophysics research, but since Professor Queloz’s discovery in 1995 it has grown exponentially. One of the most interesting aspects of the research is the search for Earth-like planets which have the ability to support life. This research hopes to shed light on the evolution of Earth’s own atmosphere and the burgeoning field of bioastrophysics.

The new professor will eventually be based at the Cavendish’s Battcock Centre for Experimental Astrophysics, a new building which plans to capitalise on the exciting developments in astronomy and will open in September 2013. Sited next to the Kavli Institute for Cosmology and the Institute of Astronomy, the Centre will reinforce Cambridge’s global reputation as a world-class centre of research excellence in all aspects of astrophysics and cosmology.

Professor Queloz will arrive in early Spring 2013 and will continue to maintain a part-time connection with the University of Geneva, as one of the world’s leading exoplanet research centres.


New professor is one of the joint discoverers of a planet orbiting a normal star beyond the Solar System.

I am delighted to be moving to Cambridge. It is a real honour for me to join a University which has been the home and source of inspiration to so many great scientists.
Professor Didier Queloz
This artist's impression shows a gas-giant exoplanet transiting across the face of its star. Infrared analysis by NASA's Spitzer Space Telescope.

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Quantum kisses change the colour of nothing

Nano-sized balls of gold

Even empty gaps have a colour. Now scientists have shown that quantum jumps of electrons can change the colour of gaps between nano-sized balls of gold. The new results, published today in the journal Nature, set a fundamental quantum limit on how tightly light can be trapped.

The team from the Universities of Cambridge, the Basque Country and Paris have combined tour de force experiments with advanced theories to show how light interacts with matter at nanometre sizes. The work shows how they can literally see quantum mechanics in action in air at room temperature.

Because electrons in a metal move easily, shining light onto a tiny crack pushes electric charges onto and off each crack face in turn, at optical frequencies. The oscillating charge across the gap produces a ‘plasmonic’ colour for the ghostly region in-between, but only when the gap is small enough.

Team leader Professor Jeremy Baumberg from the University of Cambridge Cavendish Laboratory suggests we think of this like the tension building between a flirtatious couple staring into each other’s eyes. As their faces get closer the tension mounts, and only a kiss discharges this energy.

In the new experiments, the gap is shrunk below 1nm (1 billionth of a metre) which strongly reddens the gap colour as the charge builds up. However because electrons can jump across the gap by quantum tunnelling, the charge can drain away when the gap is below 0.35nm, seen as a blue-shifting of the colour. As Baumberg says, “It is as if you can kiss without quite touching lips.”

Matt Hawkeye, from the experimental team at Cambridge, said: “Lining up the two nano-balls of gold is like closing your eyes and touching together two needles strapped to the end of your fingers. It has taken years of practise to get good at it.”

Prof Javier Aizpurua, leader of the theoretical team from San Sebastian complains: “Trying to model so many electrons oscillating inside the gold just cannot be done with existing theories.” He has had to fuse classical and quantum views of the world to even predict the colour shifts seen in experiment.

The new insights from this work suggest ways to measure the world down to the scale of single atoms and molecules, and strategies to make useful tiny devices.

The research is funded as part of a UK Engineering and Physical Sciences Research Council (EPSRC) investment in the Cambridge NanoPhotonics Centre, as well as EU and Ikerbasque funding that joins the teams together.

New insights from research suggest ways to measure the world at the scale of single atoms and molecules.

It is as if you can kiss without quite touching lips.
Professor Jeremy Baumberg from the University of Cambridge Cavendish Laboratory
Nano-sized balls of gold

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The dance of quantum tornadoes

Polariton quantum rivers flow from four hills creating quantum tornadoes in the valley

Tornado-like vortexes can be produced in bizarre fluids which are controlled by quantum mechanics, completely unlike normal liquids. New research published today in the journal Nature Communications demonstrates how massed ranks of these quantum twisters line up in rows, and paves the way for engineering quantum circuits and chips measuring motion ultra-precisely.

The destructive power of rampaging tornadoes defeats the human ability to control them. A Cambridge team has managed to create and control hundreds of tiny twisters on a semiconductor chip. By controlling where electrons move and how they interact with light the team created a marriage of electrons and photons that form a new quantum particle called a ‘polariton’.

The results come from a collaboration between the experimental team in the NanoPhotonics Centre led by Professor Jeremy Baumberg and the theoretical quantum fluids group of Dr Natalia Berloff.

Dr Berloff says: “Being half-light and half-matter these particles are feather-light and move quickly around, sloshing and cascading much like water in a mountain river.”

Most excitingly, the team says, these quantum systems are actually large, the width of a human hair, and the effects can be seen though a normal optical microscope.

Using ultra-high quality samples produced by a team from Crete the researchers exerted unprecedented control on possible flows they can arouse within this liquid: forcing it to flow down a hill, over a mountainous terrain, forming quiet lakes and wildly raging quantum oceans.

By creating polaritons at the top of several hills and letting them flow downhill the group was able to form regular arrays of hundreds of tornadoes spiralling in alternating directions along well-defined canyons. By changing the number of hills, the distance between them and the rate of polariton creation the researchers could vary the separation, the size, and number of the twister cores, achieving a long held dream of creating and controlling macroscopic quantum states.

But quantum mechanics responsible for creating such fluids makes quantum tornadoes act even more intriguingly than their classical counterparts.  Quantum vortices can only swirl around in fixed ‘quantised’ amounts and the liquids at the top of the various hills synchronize as soon as they mix down in the valleys - just two examples of quantum mechanics that can now be seen directly.

Quantum tornadoes can be reconfigured on the fly and pave the way to widespread applications in the control of quantum fluid circuits.  Creating arbitrary configurations of polariton liquids leads to even more complicated quantum superpositions and lays groundwork for polariton interferometers (devices which measure small movements and surface irregularities) that  respond extremely sensitively to even the slightest changes in the environment.

The research was funded by the Engineering and Physical Sciences Research Council and the EU.


A quantum fluid trapped on top of a semiconductor chip can be used to measure movements to astonishing precision.

Being half-light and half-matter these particles are feather-light and move quickly around, sloshing and cascading much like water in a mountain river.
Dr Natalia Berloff from the Department of Applied Mathematics and Theoretical Physics
Polariton quantum rivers flow from four hills creating quantum tornadoes in the valley

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3D microchip created


Scientists from the University of Cambridge have created, for the first time, a new type of microchip which allows information to travel in three dimensions. Currently, microchips can only pass digital information in a very limited way – from either left to right or front to back. The research was published today, 31 January, in Nature.

Dr Reinoud Lavrijsen, an author on the paper from the University of Cambridge, said: “Today’s chips are like bungalows – everything happens on the same floor. We’ve created the stairways allowing information to pass between floors.”

Researchers believe that in the future a 3D microchip would enable additional storage capacity on chips by allowing information to be spread across several layers instead of being compacted into one layer, as is currently the case.

For the research, the Cambridge scientists used a special type of microchip called a spintronic chip which exploits the electron’s tiny magnetic moment or ‘spin’ (unlike the majority of today’s chips which use charge-based electronic technology). Spintronic chips are increasingly being used in computers, and it is widely believed that within the next few years they will become the standard memory chip.

To create the microchip, the researchers used an experimental technique called ‘sputtering’. They effectively made a club-sandwich on a silicon chip of cobalt, platinum and ruthenium atoms. The cobalt and platinum atoms store the digital information in a similar way to how a hard disk drive stores data. The ruthenium atoms act as messengers, communicating that information between neighbouring layers of cobalt and platinum. Each of the layers is only a few atoms thick.

They then used a laser technique called MOKE to probe the data content of the different layers.  As they switched a magnetic field on and off they saw in the MOKE signal the data climbing layer by layer from the bottom of the chip to the top.  They then confirmed the results using a different measurement method.

Professor Russell Cowburn, lead researcher of the study from the Cavendish Laboratory, the University of Cambridge’s Department of Physics, said: “Each step on our spintronic staircase is only a few atoms high. I find it amazing that by using nanotechnology not only can we build structures with such precision in the lab but also using advanced laser instruments we can actually see the data climbing this nano-staircase step by step.

“This is a great example of the power of advanced materials science. Traditionally, we would use a series of electronic transistors to move data like this. We’ve been able to achieve the same effect just by combining different basic elements such as cobalt, platinum and ruthenium. This is the 21st century way of building things – harnessing the basic power of elements and materials to give built-in functionality.”

The research was funded by the European Research Council, the Isaac Newton Trust, and the Netherlands Organisation for Scientific Research (NWO).

New type of microchip created which not only moves information from left to right and back to front, but up and down as well.

We can actually see the data climbing this nano-staircase step by step.
Professor Russell Cowburn, lead researcher of the study from the Cavendish Laboratory, the University of Cambridge’s Department of Physics

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Finding malaria's weak spot


After over a decade of research into malaria, biologists Dr Teresa Tiffert and Dr Virgilio Lew at the Department of Physiology, Development and Neuroscience found their efforts to observe a key stage of the infection cycle severely hindered by the limits of available technology. An innovative collaboration with physicist Dr Pietro Cicuta at the Cavendish Laboratory and bio-imaging specialist Professor Clemens Kaminski in the Department of Chemical Engineering and Biotechnology is now yielding new insights into this devastating disease.

Under attack

Malaria is caused by parasites transmitted to humans through the bites of infected mosquitoes. According to the World Malaria Report 2011, there were about 216 million cases of malaria causing an estimated 655,000 deaths in 2010. Tiffert and Lew established their malaria laboratory in Cambridge in 1999 to investigate the most deadly form of the parasite, Plasmodium falciparum. Becoming increasingly resistant to available drugs, this species in particular is a growing public health concern.

Their current focus is a mysterious step in the life cycle of P. falciparum occurring inside the infected human’s bloodstream. The parasites, at this stage called merozoites, attach to and enter red blood cells (RBCs) to develop and multiply. After two days, the new merozoites are released and infect neighbouring RBCs. Over several days, this process amplifies the number of parasitised RBCs and causes severe and potentially lethal symptoms in humans.

“A huge amount of research has been devoted to understanding the RBC penetration process,” said Tiffert. “The focus of many vaccine efforts is the molecules on the surfaces of both parasite and red cell that are instrumental in recognition and penetration. Our collaboration with Clemens developed new imaging approaches to investigate what happens in the cells after invasion. But the pre-invasion stage, when a merozoite first contacts a cell targeted for invasion, remained a profound mystery. Our research indicates that this stage is absolutely critical in determining the proportion of cells that will be infected in an individual.”

For invasion to occur, the tip of the merozoite has to be aligned perpendicularly to the RBC membrane. Tiffert and Lew are focusing on how this alignment comes about, which has proved a formidable technical challenge. “The merozoites are only in the bloodstream for less than two minutes, where they are vulnerable to attack by the host’s immune system, before entering a RBC. To investigate what is going on we need to record lots of pre-invasion and penetration sequences at high speed, using high magnification and variable focusing in three dimensions. And the real challenge is to have the microscope on the right settings and to be recording at exactly the time when an infected cell has burst and released merozoites – something that is impossible to predict,” said Tiffert.

Techniques used by previous investigators have produced few useful recordings of this process occurring in culture, but from these an astonishing picture is emerging. “The contact of the merozoite with the RBC elicits vigorous shape changes in the cell, not seen in any other context,” said Lew. “It seems clear that this helps the merozoite orientate itself correctly for penetration, because all movement stops as soon as this happens. The parasite is somehow getting the RBC to help it invade.”

A collaborative approach

Cicuta, a University Lecturer involved in the University’s Physics of Medicine Initiative – which is bringing together researchers working at the interface of physical sciences, life sciences and clinical sciences – met the trio by chance three years ago. He realised he could use his background in fundamental physics to pioneer a new approach to understanding malaria. “It’s been a gradual move for me to apply what I’ve learnt in physics to biology,” he said. “From the physics point of view, RBC membranes are a material. This material is very soft and undergoes deformations and fluctuations, and I was interested in understanding the mechanics involved during infection with malaria.”

Drawing on his expertise in the development of experimental techniques, Cicuta collaborated with Tiffert, Lew and Kaminski to pioneer a completely automated imaging system that pushes the boundaries of live cell imaging, enabling individual RBCs and merozoites to be observed throughout the process of infection. The research was funded by the Biotechnology and Biological Sciences Research Council and the Engineering and Physical Sciences Research Council.

“This microscope can not only run by itself for days, it can perform all the tasks that a human would otherwise be doing. It can refocus, it can find infected cells and zoom in, and when it detects a release of parasites it can change its imaging modality by going into a high frame-rate acquisition. And when the release has finished it can search around in the culture to find another cell to monitor automatically,” said Cicuta. “We also want to integrate a technique called an optical trap, which uses a laser beam to grab cells and move them around, so we can deliver the parasites to the cells ourselves and see how they invade.”

“So far, we’ve been able to gather over 50 videos of infections, which my PhD student Alex Crick has processed to show very clearly that the RBCs undergo large changes in shape when the merozoites touch them. We’ve also seen very strange shape changes just before the parasites come out of the cells, and we want to see whether this has a bearing on the parasites’ ability to infect subsequent cells.”

During the development of the microscope, the team discovered variability in the way the infected RBCs behave before they burst. “It’s important to know that there isn’t just one story. The only way to find this out is to look at many cells, which this system allows,” said Lew. “It’s a new level of data that allows us to get experimentally significant results, and better understand the diversity of the merozoites,” Cicuta added.

Used in conjunction with other tools such as fluorescent indicators and molecular biological tools, the new technology will allow Tiffert and Lew to test their hypotheses about the pre-invasion stage of the disease. They hope to determine the critical steps, which could provide clues as to how to stop an infection. “This microscope is an extraordinary new tool that has potential for use across a huge field of biological problems involving cellular interactions,” explained Lew.

“It may provide a route to designing effective antimalarial drugs, reducing invasive efficiency and decreasing mortality,” said Tiffert. “The automation we have achieved with this microscope will also be very important for future testing of malaria drugs and vaccines,” added Cicuta.

A visionary initiative

“The Physics of Medicine Initiative has been essential to our work,” said Cicuta. The University formally established the Initiative in December 2008 through the opening of a new purpose-built research facility adjacent to the Cavendish Laboratory, funded by the University and The Wolfson Foundation. The goal is to break down traditional barriers that have tended to limit interactions between researchers in the physical and biomedical sciences.

“I met my collaborators through a Physics of Medicine symposium, and the new building is the only place in the University where this type of research can be done,” added Cicuta. “It’s set up for safe handling of hazardous biological organisms like P. falciparum, and also has the facilities to design hardware for our advanced microscopes. This work is exciting because it’s interdisciplinary. By applying physics to the knowledge biologists have been developing for many years, we can make very fast progress.”

For more information, please contact Jacqueline Garget at the University of Cambridge Office of External Affairs and Communications

A ground-breaking imaging system to track malarial infection of blood cells in real time has been created by a collaboration catalysed by the University’s Physics of Medicine Initiative.

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Graphene joins the race to redefine the ampere


The world’s first graphene single-electron pump (SEP), described in a paper in Nature Nanotechnology, provides the speed of electron flow needed to create a new standard for electrical current based on electron charge. The international system of units (SI) comprises seven base units (the metre, kilogram, second, Kelvin, ampere, mole and candela). Ideally these should be stable over time and universally reproducible. This requires definitions based on fundamental constants of nature which are the same wherever you measure them.

The present definition of the Ampere, however, is vulnerable to drift and instability. This is not sufficient to meet the accuracy needs of present and certainly future electrical measurement. The highest global measurement authority, the Conférence Générale des Poids et Mesures, has proposed that the ampere be re-defined in terms of the electron charge.

The front runner in this race to redefine the ampere is the single-electron pump (SEP). SEPs create a flow of individual electrons by shuttling them in to a quantum dot – a particle holding pen – and emitting them one at a time and at a well-defined rate.  The paper published today describes how a graphene SEP has been successfully produced and characterised for the first time, and confirms its properties are extremely well suited to this application.

A good SEP pumps precisely one electron at a time to ensure accuracy, and pumps them quickly to generate a sufficiently large current. Up to now the development of a practical electron pump has been a two-horse race. Tuneable barrier pumps use traditional semiconductors and have the advantage of speed, while the hybrid turnstile utilises superconductivity and has the advantage that many can be put in parallel. Traditional metallic pumps, thought to be not worth pursuing, have been given a new lease of life by fabricating them out of the world’s most famous super-material - graphene.

Previous metallic SEPs made of aluminium are very accurate, but pump electrons too slowly for making a practical current standard. Graphene’s unique semimetallic two-dimensional structure has just the right properties to let electrons on and off the quantum dot very quickly, creating a fast enough electron flow - at near gigahertz frequency - to create a current standard. The Achilles' heel of metallic pumps, slow pumping speed, has thus been overcome by exploiting the unique properties of graphene.

The scientist at NPL and Cambridge's Department of Physics still need to optimise the material and make more accurate measurements, but today’s paper marks a major step forward in the road towards using graphene to redefine the ampere.

The realisation of the ampere is currently derived indirectly from resistance or voltage, which can be realised separately using the quantum Hall effect and the Josephson Effect. A fundamental definition of the ampere would allow a direct realisation that National Measurement Institutes around the world could adopt. This would shorten the chain for calibrating current-measuring equipment, saving time and money for industries billing for electricity and using ionising radiation for cancer treatment.

Current, voltage and resistance are directly correlated. Because we measure resistance and voltage based on fundamental constants – electron charge and Planck’s constant - being able to measure current would also allow us to confirm the universality of these constants on which many precise measurements rely.

Graphene is not the last word in creating an ampere standard. NPL and others are investigating various methods of defining current based on electron charge. But today’s paper suggests graphene SEPs could hold the answer. Also, any redefinition will have to wait until the Kilogram has been redefined. This definition, due to be decided soon, will fix the value of electronic charge, on which any electron-based definition of the ampere will depend.

The paper also has important implications beyond measurement. Accurate SEPs operating at high frequency and accuracy can be used to make electrons collide and form entangled electron pairs. Entanglement is believed to be a fundamental resource for quantum computing, and for answering fundamental questions in quantum mechanics.

Malcolm Connolly, a research associate at Cambridge, said : “This paper describes how we have successfully produced the first graphene single-electron pump. We have work to do before we can use this research to redefine the ampere, but this is a major step towards that goal. We have shown that graphene outperforms other materials used to make this style of SEP. It is robust, easier to produce, and operates at higher frequency. Graphene is constantly revealing exciting new applications and as our understanding of the material advances rapidly, we seem able to do more and more with it.”

Text courtesy of the National Physical Laboratory.

A new joint innovation by the University of Cambridge and the National Physical Laboratory (NPL), the UK’s National Measurement Institute, could pave the way for redefining the ampere in terms of fundamental constants of physics.

Graphene is constantly revealing exciting new applications and as our understanding of the material advances rapidly, we seem able to do more and more with it
Malcolm Connolly
Electron pumps made from graphene work ten times faster than similar pumps made from conventional three-dimensional materials and can be used to generate larger currents

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Unraveling tumor growth one stem cell at a time


Researchers at the University of Cambridge have discovered that a single mutation in a leukemia-associated gene reduces the ability of blood stem cells to make more blood stem cells, but leaves their progeny daughter cells unaffected. Their findings have relevance to all cancers that are suspected to have a stem cell origin as they advance our understanding of how single stem cells are subverted to cause tumors.

Published this week in PLOS Biology, the study by Professor Tony Green and his team at the Cambridge Institute for Medical Research (CIMR) is the first to isolate highly purified single stem cells and study their individual responses to a mutation that can predispose individuals to a human malignancy. This mutation is in a gene called JAK2, which is present in most patients with myeloproliferative neoplasms (MPNs)—a group of bone marrow diseases that are characterized by the over-production of mature blood cells and by an increased risk of developing leukemia.

Using a unique mathematical modeling approach, carried out in collaboration with Professor Ben Simons at the Cavendish Laboratory in Cambridge, in combination with experiments on single mouse stem cells, the researchers identified a distinct cellular mechanism that operates in stem cells but not in their daughter cells. 

“This study is an excellent example of an inter-disciplinary collaboration pushing the field forward,” says lead author Dr David Kent. “Combining mathematical modeling with a large number of single stem cell assays allowed us to predict which cells lose their ability to expand. We were able to reinforce this prediction by testing the daughter cells of single stem cell divisions separately and showing that mutant stem cells more often undergo symmetric division to give rise to two non-stem cells.”

Characterizing the mechanisms that link JAK2 mutations with this pattern of stem cell division—a pattern that eventually leads to the development of MPNs—will inform our understanding of the earliest stages of tumor establishment and of the competition between tumor stem cells, say the authors. The next step, currently underway at the Cambridge Institute for Medical Research, is to understand the effect that acquiring additional mutations has on blood stem cells, as these are  thought to drive the expansion of blood progenitor cells, leading to the eventual transformation to leukemia that occurs in patients with MPNs.

Citation: Kent DG, Li J, Tanna H, Fink J, Kirschner K, et al. (2013) Self-Renewal of Single Mouse Hematopoietic Stem Cells Is Reduced by JAK2V617F Without
Compromising Progenitor Cell Expansion. PLoS Biol 11(6): e1001576. doi:10.1371/journal.pbio.1001576

Press release provided by PLOS Biology.

Study has relevance to all cancers that are suspected to have a stem cell origin

A small colony of cells derived from a single blood stem cell. Hundreds of such colonies were assessed for their proliferation kinetics and blood cell types produced.

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New Centre will bring together frontier physics research and the needs of industry


Combined government and business funding of £63 million has been announced today for the creation of a new centre at the Cavendish Laboratory on the West Cambridge site dedicated to world-class research in the physical sciences, and how it translates to industry.

Leading scientists backing the centre believe it will bring forward the scale of industrial engagement in West Cambridge “by a decade” for the benefit of British industry, economy and “society in general”.

The centre will build on the innovative activity currently supported by the Winton Programme for the Physics of Sustainability at Cambridge’s Cavendish Laboratory, where the focus has been on truly original, risk-taking science since its inception in March 2011, emphasising fundamental physics research relevant to areas such as renewable energy – including photovoltaics and electrical storage.

The new facilities will see research scientists from industry occupying laboratory and desk space alongside the Cambridge research groups, with the aim of engendering a two-way flow of ideas and exposing the best early career researchers in academe and industry to scientific problem-solving that relates directly to industrial need.

Funding for the project from the non-governmental sector was raised partly through philanthropic gifts from the Winton programme, Hitachi Ltd., Toshiba Ltd., the Wolfson Foundation, the Sackler Foundation and Tata Steel. These contributions were doubled by industrial contracts with a very wide range of industries, including those collaborating with cognate departments such as Materials Science and Chemistry. The Higher Education Funding Council for England (HEFCE) is providing £21m to complement the non-governmental sources of funding for the programme.

Construction work will begin shortly on the Maxwell Centre, provisionally named for the great physicist James Clerk Maxwell, who was appointed the first Professor of Experimental Physics at Cambridge in 1871 and who discovered electromagnetism and founded statistical mechanics, among other insights of genius. The building is due to open its doors in the summer of 2015.

“The Maxwell Centre will be the vehicle for translating ‘blue skies’ research into products of importance for the industrial sector,” said Professor Sir Richard Friend, Cavendish Professor of Physics, who will be the first Director of the Centre.

“This will not be conventional research or ‘business as usual’, but a major effort to go beyond the boundaries of traditional physical science concepts. The key to innovation is an effective bottom-up approach to fundamental research. We will combine work on the specific challenges facing collaborators with research into areas at the edges of current conception – the ‘unknown unknowns’”.  

Pioneering research from the Winton programme – established by a £20m donation from David Harding, founder of Winton Capital Management – will be able to flourish in the Maxwell Centre. This will include work on quantum-level modelling of biological systems such as avian navigation and photosynthesis in deep-sea bacteria to enhance energy efficiency, and the new physics of materials that could harness superconductivity to revolutionise battery life. 

Many other aspects of fundamental physics will be fostered, including advanced scientific computing, the theory of condensed matter, advanced materials and the physics of biology and medicine. 

This will be balanced with embedded industrial partners in the Centre and graduate programmes designed to prepare students for the challenges of research and development in industry, attracting increasing investment and creating “cohorts of graduate students prepared for employment in high-tech industries,” said Friend.

“Many of the most exciting and unexpected research opportunities lie at the interface between academia and industry, it is genuinely a two-way process. Many innovations in science, designed to solve pure science problems, are applied in quite different areas - often those of greatest interest to industry.”

George Osborne, Chancellor of the Exchequer, said: "By bringing together our Nobel Prize winning scientists, our world-class companies and our entrepreneurial start-ups, we can drive innovation and create the economic dynamism Britain needs, using public money to secure private investment so our world-class science also delivers jobs and growth.”

David Willetts, Minister for Universities and Science, said he believes this project will “not only deliver new knowledge and applications for industry, but will accelerate growth and foster innovation between the research base and business, keeping the UK ahead in the global race.”  

Professor Sir Leszek Borysiewicz, Vice Chancellor of the University of Cambridge, said: "The University has already invested very heavily to build up our research base on the West Cambridge science and technology campus, and through the Maxwell Centre, we will capitalise on this resource by embedding industrial engagement still further into the University.”

“Links between new science and real applications are very well established in the Physical Sciences. This is evident from the very large and diverse set of industrial partners who are co-investors in the Maxwell Centre. We are determined that the Maxwell Centre will be the centrepiece for a very substantial growth in our industrial engagement in the Physical Sciences. This builds on real excellence in research, an outstanding student base and very strong and enthusiastic collaborations with a broad range of industries.”

Subject to planning permission, the Maxwell Centre will be located between the Physics of Medicine building and the William Gates building – home of the Computer Laboratory – on the 20-acre West Cambridge site, and will house around 230 people in the first instance, with research laboratories complemented by seminar rooms, interactive spaces and dedicated hubs for industrial partners. This new building is part of the Cavendish Laboratory’s long-term development programme.

Professor Malcolm Longair, former Head of the Cavendish and its current Development Director, added that he hopes to confirm the Centre’s name soon as a fitting tribute to Clerk Maxell, the physicist of “outstanding genius who was the essential bridge between Newton and Einstein.”

“Maxwell was a truly great figure, and his approach to theoretical and experimental science mirrors exactly what we want to achieve in this new building.”

A centrepiece building for exploratory ‘blue skies’ research and industrial partnerships in the physical sciences will be created at the University of Cambridge to investigate new approaches to fundamental science and to solving global challenges, such as natural resource demand.

This will not be conventional research or ‘business as usual’, but a major effort to go beyond the boundaries of traditional physical science concepts
Richard Friend
Architect’s impression of the new Maxwell Centre for physical science research, due to open in summer 2015.

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Molecular ‘sieves’ harness ultraviolet irradiation for greener power generation


New research shows that exposing polymer molecular sieve membranes to ultraviolet (UV) irradiation in the presence of oxygen produces highly permeable and selective membranes for more efficient molecular-level separation, an essential process in everything from water purification to controlling gas emissions.

Published in the journal Nature Communications, the study finds that short-wavelength UV exposure of the sponge-like polymer membranes in the presence of oxygen allows the formation of ozone within the polymer matrix. The ozone induces oxidation of the polymer and chops longer polymer chains into much shorter segments, increasing the density of its surface.

By controlling this ‘densification’, resulting in smaller cavities on the membrane surface, scientists have found they are able to create a greatly enhanced ‘sieve’ for molecular-level separation - as these ‘micro-cavities’ improve the ability of the membrane to selectively separate, to a significant degree, molecules with various sizes, remaining highly permeable for small molecules while effectively blocking larger ones.

The research from the University of Cambridge’s Cavendish Laboratory partly mirrors nature, as our planet’s ozone layer is created from oxygen hit by ultraviolet light irradiated from the sun.

Researchers have now demonstrated that the ‘selectivity’ of these newly modified membranes could be enhanced to a remarkable level for practical applications, with the permeability potentially increasing between anywhere from a hundred to a thousand times greater than the current commercially-used polymer membranes.

Scientists believe such research is an important step towards more energy efficient and environmentally friendly gas-separation applications in major global energy processes - ranging from purification of natural gases and hydrogen for sustainable energy production, the production of enriched oxygen from air for cleaner combustion of fossil fuels and more-efficient power generation, and the capture of carbon dioxide and other harmful greenhouse gases.

“Our discoveries lead to better understandings of physics of the novel materials, so we will be able to develop better membranes in the future" said Qilei Song, a researcher in Dr Easan Sivaniah’s group and the paper's lead author.

In collaboration with groups at the Department of Materials Science and Metallurgy (Professor Tony Cheetham), University of Cambridge, and at the Chemical Engineering department of Qatar University (Prof. Shaheen Al-Muhtaseb), the researchers confirmed that the size and distribution of free volume accessible to gas molecules within these porous polymeric molecular sieves could be tuned by controlling the kinetics of the ultraviolet light-driven reactions.

Conventional separation technologies, such as cryogenic distillation and amine absorption, are significantly energy-intensive processes. Membrane separation technology is highly attractive to industry, as it has the potential to replace conventional technologies with higher energy efficiency and lower environmental impacts.

But gas separation performance of current commercially-available polymer membranes are subject to what scientists describe as “a poor trade-off” between low permeability levels and high degree of selective molecular separation. The next generation membranes – such as polymers of intrinsic microporosity (PIMs) - being studied at the Cavendish are based on tuning the pore size and interaction with specific molecules to achieve both high permeability and, critically, high selectivity.

Currently, these flat-sheet membranes show great separation performance and are mechanically robust for clean cylinder gases. “We are working on ways to further improve these membranes and our next step is to develop large scale and more practical industrial modules such as thin film composite membranes or hollow fibers with selective layer as thin as possible,” said Dr Easan Sivaniah.

“We are also exploring many other applications of these fascinating polymer materials, such as liquid and vapour separation, water treatment by desalination, sensor devices and photolithography technology, and energy storage applications".

Latest research uses membrane technology for ‘energy efficient’ gas separation - a crucial part of many major industrial processes and important focus for increased sustainability in global energy production.

Our next step is to develop large scale and more practical industrial modules
Easan Sivaniah
Image shows fluorescence of solution (left) and membrane (right) made of a polymer of intrinsic microporosity (PIM-1) under irradiation of ultraviolet (UV) light. The ultraviolet irradiation induces oxidation and surface densification of the polymeric m

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Electron ‘spin’ key to solar cell breakthrough


Organic solar cells, a new class of solar cell that mimics the natural process of plant photosynthesis, could revolutionise renewable energy - but currently lack the efficiency to compete with the more costly commercial silicon cells.

At the moment, organic solar cells can achieve as much as 12 per cent efficiency in turning light into electricity, compared with 20 to 25 per cent for silicon-based cells.

Now, researchers have discovered that manipulating the 'spin' of electrons in these solar cells dramatically improves their performance, providing a vital breakthrough in the pursuit of cheap, high performing solar power technologies.

The study, by researchers from the Universities of Cambridge and Washington, is published today in the journal Nature, and comes just days after scientists called on governments around the world to focus on solar energy with the same drive that put a man on the moon, calling for a "new Apollo mission to harness the sun's power".

Organic solar cells replicate photosynthesis using large, carbon-based molecules to harvest sunlight instead of the inorganic semiconductors used in commercial, silicon-based solar cells. These organic cells can be very thin, light and highly flexible, as well as printed from inks similar to newspapers - allowing for much faster and cheaper production processes than current solar cells.

But consistency has been a major issue. Scientists have, until now, struggled to understand why some of the molecules worked unexpectedly well, while others perform indifferently.

Researchers from Cambridge's Cavendish Laboratory developed sensitive laser-based techniques to track the motion and interaction of electrons in these cells. To their surprise, the team found that the performance differences between materials could be attributed to the quantum property of 'spin'.

'Spin' is a property of particles related to their angular momentum, with electrons coming in two flavours, 'spin-up' or 'spin-down'. Electrons in solar cells can be lost through a process called 'recombination', where electrons lose their energy - or "excitation" state - and fall back into an empty state known as the "hole".

Researchers found that by arranging the electrons 'spin' in a specific way, they can block the energy collapse from 'recombination' and increase current from the cell.

"This discovery is very exciting, as we can now harness spin physics to improve solar cells, something we had previously not thought possible. We should see new materials and solar cells that make use of this very soon" said Dr. Akshay Rao, a Research Fellow at the Cavendish Laboratory and Corpus Christi College, Cambridge, who lead the study with colleagues Philip Chow and Dr. Simon Gélinas.

The Cambridge team believe that design concepts coming out of this work could help to close the gap between organic and silicon solar cells, bringing the large-scale deployment of solar cells closer to reality. In addition, some of these design concepts could also be applied to Organic Light Emitting diodes, a new and rapidly growing display technology, allowing for more efficient displays in cell phones and TVs.

The short film clip above shows the researchers at work in the lab with the web of lasers they used in the research. Simon Gélinas explained that these laser techniques "make ultrafast movies at approximately one million billion frames per second", allowing the team to monitor what happens "from the moment the light is absorbed in the device until electrical current comes out".

"Through this, we've identified what mechanisms prevent the loss of electrical current in good organic solar cells. Now we can design materials knowing specifically how to harvest the most out of this process," he added.

The work on solar cells at Cambridge forms part of a broader initiative to harness high tech knowledge in the physics sciences to tackle global challenges such as climate change and renewable energy. This initiative is backed by both the UK Engineering and Physical Sciences Research Council and, in Cambridge, the Winton Programme for the Physics of Sustainability. The work at the University of Washington was supported by the US National Science Foundation and the U.S. Office of Naval Research.

Latest research paves way for inexpensive, high performance cells

We should see new materials and solar cells that make use of this very soon
Akshay Rao
The laser set-up in the lab that led to the research results

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Winton Symposium‘s material world


This year’s focus on ‘Materials Discovery’ will bring together leading scientists from around the world, revealing unexpected breakthroughs in a wide range of subjects from electronics to life sciences.

Attendance is free, and with last year’s inaugural ‘Energy Efficiency’ event drawing a large audience of researchers and industrialists from a range of disciplines, the event promises to be popular - so pre-registration is essential.

This year’s sessions for the one-day symposium will be:

Session I

Professor Chris Wise, designer of the award-winning London 2012 Velodrome, will open the symposium by focusing on sustainability in the engineering industry. Exploring current thoughts on demand reduction, the global problem of shrinking resources and an expanding population, Wise will discuss how these issues can inform innovative building design.

Session II

From great structures to the microscopic, graphene Nobel prize-winner Professor Sir Konstantin Novoselov from the University of Manchester will explore the world of ultrathin films and their unexpected properties. This will be followed by Professor Paul Alivisatos, Director of the Lawrence Berkeley National Laboratory, one of the pioneers in the field of nanocrystals, who will address the design of these minute structures and reveal their practical applications.

Session III

Professor Jason Chin from the Cambridge/MRC Laboratory of Molecular Biology will delve into the building blocks of biological world. Despite their complexity, Chin will show how these structures can be manipulated to create new forms of functional materials, and share his research into the production of artificial genetic code. Professor Daniel Fletcher from University of California, Berkeley, who has been studying the mechanics and dynamics of cell movement, will look at the self-organisation of biological structures.

Session IV

Finally, two leading scientists with backgrounds in chemistry will cover their latest breakthroughs. Professor Ben Feringa from the University of Groningen has designed a wide range of synthetic materials, and will talk about his leading research in the field of 'molecular motors'. Professor George Whitesides, one of the leading material scientists of his generation and Professor at Department of Chemistry at Harvard University will discuss his multi- disciplinary research with applications ranging from biology to microelectronics.

Dr Nalin Patel, Programme Manager for Winton Programme, said: “We are delighted to welcome world-leading scientists to Cambridge to explore some of the recent breakthroughs in materials research, and how they may have an impact on societies needs in the future.”

The symposium is free of charge to pre-registered attendees and will include a free lunch.

For registration visit: http://www.phy.cam.ac.uk/conferences/materialsdiscovery/form/booking.php

For more information visit: http://www.phy.cam.ac.uk/conferences/materialsdiscovery/furtherinfo.php

For more information, please contact Dr Nalin Patel: nlp28@cam.ac.uk; 01223 760302

On 30 September, the Department of Physics will host the second annual Winton Symposium at the Cavendish Laboratory on ‘Materials Discovery’.

We are delighted to welcome world-leading scientists to Cambridge to explore some of the recent breakthroughs in materials research, and how they may have an impact on societies needs in the future
Dr Nalin Patel, Programme Manager for Winton Programme
SEM image of 1-5 micrometer large silica particles attached to 50 micrometer large paraffin spheres

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Inspired by nature


Through billions of years of evolution, life on Earth has found intricate solutions to many of the problems scientists are currently grappling with. Physicists at the University of Cambridge’s Cavendish Laboratory are trying to unravel nature’s secrets to develop new energy-generating technologies for a more sustainable future.

Focusing on the ancient green sulphur bacteria, research fellows Dr Alex Chin and Dr Nicholas Hine are investigating the early stages of photosynthesis – the process in which plants and some bacteria capture the sun’s light energy and convert it into chemical energy, or food.

“The light-harvesting states of photosynthesis are highly efficient in many species, and happen extremely fast – within a nanosecond, if not picoseconds,” said Chin. “We’re very interested in that efficiency and how it’s managed. Biology has evolved phenomenally subtle systems to funnel light energy around and channel it to the right places. It has also become incredibly good at building tiny devices that work with high efficiency, and at replicating them millions of times.”

Green sulphur bacteria are found in places with very little light, including at the bottom of the oceans, and have existed for billions of years by harvesting light extremely efficiently in order to photosynthesise. Chin and Hine are trying to discover the intimate detail of the bacteria’s clever solutions to capturing and converting light energy. “The idea is to tease out what the trick is,” said Chin. “We’d like to learn, understand and in some sense copy this in artificial systems.”

“Light harvesting is one area where evolution has produced systems that take advantage of quantum mechanics,” said Hine. “I simulate the materials involved from first principles. If you know where the atoms are, you can describe the system using only what we know about quantum mechanics.”

“We need to know about the molecular arrangements to identify the properties that lead to this high efficiency,” added Chin. “I use Nick’s simulations as input into a model I can set in motion, to see how energy will flow.” By working together, the pair is developing an understanding of this photosynthetic system, from where each individual atom is positioned to how the whole system functions.

The idea is to generate broader design principles for new nanomaterials that can be used to build better types of photovoltaic device, or solar cell. “Once we understand the system, we can then move into synthetic chemistry, solid state physics and materials science, and see if we can mimic it,” said Chin. “This may be in a simpler way, but hopefully a scalable one that is useful for industry.”

“Ultimately we want to make devices that harvest the maximum amount of the available sunlight,” said Hine. “Existing materials, like the solar cells on people’s roofs, only absorb about 20% of energy from the sun to turn into electricity. The trick is to make sure the material is tailored to absorb all the energy it possibly can. This way, solar panels become an increasingly attractive source of sustainable energy in the future.”

“Most current ways of building photovoltaic materials have been arrived at to a great extent by chance,” said Hine. “We’re taking a step back and asking whether we can work out from simulations how well materials are going to perform. The materials science of the last century was focused on bulk materials, but now it’s all about introducing structure on a smaller scale.”

To maximise the efficiency of solar cells of the future, physicists are taking a leaf out of nature’s book.

The materials science of the last century was focused on bulk materials, but now it’s all about introducing structure on a smaller scale
Nicholas Hine
A pioneering programme

As Winton Advanced Research Fellows, Chin and Hine are among the first scientists to be offered postdoctoral positions within the prestigious Winton Programme for the Physics of Sustainability. The programme was created in 2011 with a pledge of £20 million from David Harding, the founder, chairman and head of research of Winton Capital Management. His goal is to make new technologies available that address the big sustainability challenges facing society, by promoting fundamental science under the broad remit of sustainability.

“The Winton Programme is a brilliant opportunity to get established as a scientist,” said Hine. “The Fellowships give you a chance to launch your own independent research, and also collaborate with a huge network of people in Cambridge doing sustainability research in one way or another.”

“The Physics of Sustainability defines a grand challenge,” said Professor Sir Richard Friend, Director of the Winton Programme. “Sustainability is about finding better solutions in areas where we use huge amounts of material, like lighting, batteries and water-purification systems. These are areas where current solutions are inefficient and we should be able to do much better.”

In June 2013, Cambridge was awarded £21 million in government funding from the Higher Education Funding Council for England (HEFCE) towards the construction of The Maxwell Centre, where blue skies physics research will be translated into industrial applications. This £63 million centrepiece of the Cavendish’s redevelopment will house the Winton Programme in addition to research scientists from other Cambridge research groups and industry.

“The Maxwell Centre will be a one-stop-shop for physical sciences on the West Cambridge site, helping to grow our industry-facing activities,” said Friend. “We need to be opportunistic and be confident that where we have great ideas and enthusiastic scientists, industry will back us. The Centre is a great opportunity to set up labs oriented towards Winton activities.”

“David Harding talks about keeping the skies blue,” said Friend. “His funding means we can be bold and start activities we couldn’t have done otherwise, because they’re too early-stage, or don’t fit the areas funded through traditional routes. We are giving very bright younger scientists a lot of freedom to build up new research programmes, and that way I hope we will cause things to happen that wouldn’t have happened otherwise.”

The programme also provides PhD studentships, support for new academic staff, investment in research infrastructure of the highest level, pump-priming for novel research projects, support for collaborations within the University and outside, and sponsorship for meetings and outreach activities.

Friend is keen to point out that, despite centuries of breakthroughs in science that have brought us to the present day, the opportunities ahead are just as great. “There is everything still to discover, and most of it will turn out to be, for unexpected reasons, remarkably useful.”


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Building ‘nanomachines’ in biological outer space


Cambridge scientists have uncovered the mechanism by which bacteria build their surface propellers (flagella) – the long extensions that allow them to swim towards food and away from danger. The results, published this week in the journal Nature, demonstrate how the mechanism is powered by the subunits themselves as they link in a chain that is pulled to the flagellum tip.

Previously, scientists thought that the building blocks for flagella were either pushed or diffused from the flagellum base through a central channel in the structure to assemble at the flagellum tip, which is located far outside the cell. However, these theories are incompatible with recent research showing that flagella grow at a constant rate. The completely new and unexpected chain mechanism, in which subunits linked in a chain ‘pull themselves’ through the flagellum, transforms understanding of how flagellum assembly is energised.

The research was led by Dr Gillian Fraser and Professor Colin Hughes in the University’s Department of Pathology and was funded by the Wellcome Trust.

Dr Lewis Evans, who carried out the research, remarked: “It’s exciting how economical bacteria are, able to harness the thermal free energy from unfolded subunits and convert it into a coherent directed transport. More broadly, it’s fascinating to imagine the implications for how heat energy (normally considered as ‘lost’) might be harnessed to drive processes even outside living cells.”

As each flagellum ‘nanomachine’ is assembled, thousands of subunit ‘building blocks’ are made in the cell and are then unfolded and exported across the cell membrane. Like other processes inside cells, this initial export phase consumes chemical energy.  However, when subunits pass out of the cell into the narrow channel at the center of the growing flagellum, there is no conventional energy source and they must somehow find the energy to reach the tip.

The team has shown that at the base of the flagellum, subunits connect by head-to-tail linkage into a long chain. Together with Professor Eugene Terentjev, at the Cavendish Laboratory, they showed that the chain is pulled through the entire length of the flagellum channel by the entropic force of the unfolded subunits themselves. This produces tension in the subunit chain, which increases as each subunit refolds and incorporates into the tip of the growing structure. This pulling force automatically adjusts with increasing flagellum length, providing a constant rate of subunit delivery to the assembly site at the tip.

Professor Terentjev noted that this breakthrough can be applied to other fields. “Understanding how polymers move through channels is a fundamental physical problem. Gaining insight into this has potential applications in other disciplines, for instance in nanotechnology, specifically the building of new nanomaterials.”

This research has far-reaching implications, according to Fraser.  “By understanding the base-level, fundamental biology of medically important bacteria and their construction of flagella and related toxin-injecting molecular syringes,” she commented, “we can start to develop new ways to counteract them.”

Dr Gillian Fraser is at Queens' College; Professor Colin Hughes is at Trinity College; Professor Eugene Terentjev is at Queens' College

New research reveals how bacteria construct tiny flagella ‘nanomachines’ outside the cell.

It’s exciting how economical bacteria are, able to harness the thermal free energy from unfolded subunits and convert it into a coherent directed transport
Dr Lewis Evans
Flagellated cell

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Two for one in solar power


Solar cells offer the opportunity to harvest abundant, renewable energy. Although the highest energy light occurs in the ultraviolet and visible spectrum, most solar energy is in the infrared.

There is a trade-off in harvesting this light, so that solar cells are efficient in the infrared but waste much of the energy available from the more energetic photons in the visible part of the spectrum.

When a photon is absorbed it creates a single electronic excitation that is then separated into an electron and a positively charged hole, irrespective of the light energy. One way to improve efficiency is to split energy available from visible photons into two, which leads to a doubling of the current in the solar cell. 

Researchers in Cambridge and Mons have investigated the process in which the initial electronic excitation can split into a pair of half-energy excitations. This can happen in certain organic molecules when the quantum mechanical effect of electron spin sets the initial spin ‘singlet’ state to be double the energy of the alternative spin ‘triplet’ arrangement.

The study, published in the journal Nature Chemistry, shows that this process of singlet fission to pairs of triplets depends very sensitively on the interactions between molecules.  By studying this process when the molecules are in solution it is possible to control when this process is switched on. When the material is very dilute, the distance between molecules is large and singlet fission does not occur. When the solution is concentrated, collisions between molecules become more frequent.

The researchers find that the fission process happens as soon as just two of these molecules are in contact, and remarkably, that singlet fission is then completely efficient—so that every photon produces two triplets.

This fundamental study provides new insights into the process of singlet fission and demonstrates that the use of singlet fission is a very promising route to improved solar cells. Chemists will be able to use the results to make new materials, say the team from Cambridge’s Cavendish Laboratory, who are currently working on ways to use these solutions in devices.        

“We began by going back to fundamentals; looking at the solar energy challenge from a blue skies perspective,” said Dr Brian Walker, a research fellow in the Cavendish Lab’s Optoelectronics group, who led the study.

“Singlet fission offers a route to boosting solar cell efficiency using low-cost materials. We are only beginning to understand how this process works, and as we learn more we expect improvements in the technology to follow.”

The team used a combination of laser experiments - which measure timings with extreme accuracy - with chemical methods used to study reaction mechanisms. This dual approach allowed the researchers to slow down fission and observe a key intermediate step never before seen.

“Very few other groups in the world have laser apparatus as versatile as ours in Cambridge,” added Andrew Musser, a researcher who collaborated in the study. “This enabled us to get a step closer to working out exactly how singlet fission occurs.”

The research was supported by the UK Engineering and Physical Sciences Research Council, the European Community’s Initial Training Network SUPERIOR, the FNRS in Belgium, the Herchel Smith Fund, and the Winton Programme for the Physics of Sustainability.

A process that could revolutionise solar energy harvesting has been efficiently demonstrated in solution for the first time.

We are only beginning to understand how this process works, and as we learn more we expect improvements in the technology to follow
Brian Walker
Left: Laser apparatus used to study singlet fission in Cambridge. Right: Celestia sun

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Cambridge awarded major EPSRC funding for doctoral centres to train tomorrow’s engineers and scientists


Details of how a £350 million grant from the Engineering and Physical Sciences Research Council (EPSRC) will be funding over 70 new Centres for Doctoral Training (CDTs) across 24 UK universities, including Cambridge, in engineering and the physical sciences will be announced today by David Willetts, Universities and Science Minister.

University of Cambridge academics have won six of their bids for CDT funding, including the renewal of two that are currently running, and are partners in two further successful bids from UCL and Liverpool. The total value of the grant will be around £30 million, spread over 8 years, with the first cohorts to start in October 2014; the funding is targeted at areas considered to be crucial to the country’s economic growth.

Willetts said: “Scientists and engineers are vital to our economy and society. It is their talent and imagination, as well as their knowledge and skills, that inspire innovation and drive growth across a range of sectors, from manufacturing to financial services.

“I am particularly pleased to see strong partnerships between universities, industry and business among the new centres announced today. This type of collaboration is a key element of our industrial strategy and will continue to keep us at the forefront of the global science race.”

The EPSRC is the UK’s main agency for funding research in engineering and the physical sciences, and invests in research and postgraduate training to help the nation handle the next generation of technological change. These CDTs are funded for four years and include technical and transferrable skills, as well as a research element, bringing together diverse areas of expertise to train engineers and scientists with the skills.

The existing Cambridge Nano CDT is one of the Centres whose funding has been renewed, enabling the over 500 Nano researchers to continue successfully working in a multitude of disciplines, including physics, chemistry, engineering and materials. This funding follows recent investments exceeding £200 million in support of Cambridge Nano research, and new buildings for the Cavendish Laboratory. The Centre will work with a raft of companies including Nokia and Unilever to help the UK develop a lead in exploiting NanoTechnologies. Director Professor Baumberg is delighted, commenting that “our high-calibre interdisciplinary student cohorts will be Nano’s future leaders”. 

A Centre of Gas Turbine Aerodynamics is to be one of the newly-created CDTs, set to become an international centre of excellence aimed at training the next generation of leaders in research and industry. It will bring together the Universities of Cambridge, Oxford and Loughborough, along with the internationally successful companies Rolls-Royce, Mitsubishi Heavy Industries, Siemens and Dyson, and will be assisted by a team of experts from NASA and MIT. The centre is designed to support a sector which is currently responsible for the employment of 6.8% of UK manufacturing jobs, and which, over the next 20 years, is predicted to be worth in-excess of US$1,650 billion.

Other Cambridge CDTs are set to be developed or renewed in graphene, ultraprecision, future infrastructure and computational materials, as well as a photovoltaics Centre in partnership with the University of Liverpool and a phototonics Centre in partnership with UCL.

Paul Golby, EPSRC’s Chair, said: “Centres for Doctoral Training have already proved to be a great success and the model is popular with students, business and industry. These new centres will give the country the highly trained scientists and engineers it needs and they will be equipped with skills to move on in their careers.”

Funding for six Cambridge-led Centres for Doctoral Training, along with a further two in which Cambridge are partners, across a range of physical sciences and engineering disciplines will be announced today.

This type of collaboration is a key element of our industrial strategy and will continue to keep us at the forefront of the global science race
David Willetts
Doctoral candidates from the Nanomaterials and Spectroscopy Group at the Electrical Engineering Division of the Department of Engineering

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