ISSUE 5 / JANUARY 2018
from curiosity to innovation
T HE S K Y ’ S T HE L IMI T
E ME R GING T E C HNOL OGIE S A R E P OI S E D T O T R A N S F OR M HO W W E OB S E R V E T HE E A R T H. P.19
D E LV I N G I N T O THE RED SEA Unravelling the secre t s of the world’s w a r m e s t b o d y o f w a t e r. P. 2 9
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A NE W C OMP U TAT ION A L F R A ME W OR K T O R E DUC E T IME S A ND C O S T S OF C ON S T R UC T ING F R A ME- B A S E D S T R UC T UR E S . P.56
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CLEAN WATER FOR ALL Learn more DISCOVERY.KAUST.EDU.SA
Š 2017 KAUST / ANASTASIA KHRENOVA
Optimizing methods to improve water desalination and increasing potable water opportunities is critical, especially in regions where fresh water is scarce. KAUST researchers are working to achieve breakthroughs in technologies that reduce costs to produce desalinated water and improve the efficiency of reusing water.
WELCOME LETTER Dear Friends, At KAUST, we continually strive to solve important challenges by embarking upon distinctive and novel research. In this issue of KAUST Discovery magazine, you will read about our best research contributing to solutions for the Kingdom of Saudi Arabia and the world. This issue features a deeper view into one of the Kingdom’s natural treasures—the Red Sea. Inside the Red Sea section you will learn about the cycling of microbes in the Red Sea, and their importance as the basis of food webs. You’ll also read about the ways that corals have adapted to live in this high-salinity marine environment. Historically, the Red Sea served as one of the gateways for the region to the world, facilitating the trade of goods, technology and cultural ideas. Today, our research on the Red Sea is helping the Kingdom of Saudi Arabia and the world to understand the impact of climate change, generate new knowledge on future environmental shifts, and be more responsive to the evolving economic opportunities for industry and government. The sea’s beauty and complexity is a daily inspiration, and with our extraordinary location on its shores, we enjoy the year-around memorable sunsets. Throughout this issue, you will also find inspiring stories of our impact in the areas that reflect the University’s commitment to share knowledge for the betterment of humanity—from energy solutions and computation
for the future to advances in water expertise and understanding what’s underground. There are stories of the impact and passion of our faculty and researchers. For example, the story conveying Professor Mohammed Eddaoudi’s discovery published in Science describes how he and his team developed a molecule that can remove water from gas, making the separations necessary for gas processing more efficient and environmentally friendly. Also of interest, Professor Atif Shamim’s story describing how he and his team produced 3D-printed sensors that can save lives by detecting wild fires and industrial leaks. Because much of the research at KAUST involves interdisciplinary collaborations, you will find an overlap in the stories across the Biological and Environmental Science and Engineering (BESE); Computer, Electrical and Mathematical Science and Engineering (CEMSE); and Physical Science and Engineering (PSE) Divisions. I hope you enjoy reading our stories of discovery and that our efforts to advance science and technology for local and global impact inspire you. Regards, Nadhmi A. Al-Nasr Interim President
“Our research on the Red Sea is helping the Kingdom and the world to understand the impact of climate change, generate new knowledge on future environmental shifts, and be more responsive to the evolving economic opportunities for industry and government.” K AUST DISCOVERY
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Sifting through huge amounts of data may bring better understanding of whale shark social structures, protein targets for drug therapies and diseasecausing genes.
MINING BIG DATA 6 THE AWESOME SCOPE OF BIG DATA
8 DATASET SIZE COUNTS FOR BETTER PREDICTIONS
10 CUTTING DATASETS DOWN TO SIZE
11 BRINGING SIGNALS INTO PHASE
Sifting through huge amounts of data may bring better understanding of whale shark social structures, protein targets for drug therapies and diseasecausing genes.
A statistical technique for modeling large datasets improves interpretation of climate and environmental data.
A powerful statistical tool could significantly reduce the burden of analyzing very large datasets.
A novel type of electronic component made from a blend of polymer materials could enable more effective circuitry.
14 GOOD VIBRATIONS FOR THE FUTURE OF COMPUTING
15 TINY SPEAKERS BREAK A BARRIER FOR SOUND
COMPUTATION FOR THE FUTURE 12 SMART SENSORS COULD SAVE LIVES
14 VALLEY POLARIZATION GETS A MAGNETIC BOOST
3D-printed, disposable sensors capable of detecting noxious gases and changes in temperature and humidity could revolutionize environmental monitoring.
Access to valley-polarized charge carriers by magnetic doping could transform electronics.
A vibration-driven logic gate could form the basis for the next generation of efficient, low-power computers.
A loudspeaker design could allow small devices to produce powerful low-frequency sounds.
BREAKING NEW GROUND 16 PHYSICS FORECASTS FOR FRACKING AND FUELS Physicists are playing unexpected roles in meeting future global energy challenges by modeling technologies, such as fracking.
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16 TRANSFORMING HOW WE THINK ABOUT SOILS— FROM THE GROUND UP
19 THE SKY’S THE LIMIT FOR EARTH OBSERVATION
Wind turbines suspended high in the sky have potential as an alternative power source for Saudi Arabia.
Emerging technologies are poised to transform how we observe the Earth.
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ENERGY SOLUTIONS 22 A SIMPLE ADDITIVE TO IMPROVE FILM QUALITY Simple chemicals called glycol ethers help make better perovskite thin films for solar cells.
23 A KITE THAT MIGHT FLY Wind turbines suspended high in the sky have potential as an alternative power source for Saudi Arabia.
24 A FIREFLY’S FLASH INSPIRES NEW NANOLASER LIGHT Synchronized emissions from innovative on-chip lasers create possibilities for inexpensive artificial neural networks.
26 IGNITING FUTURE FUEL RESEARCH Simple two-component mixtures are good surrogates for studying the ignition properties of nextgeneration gasolines.
EXPLORING THE RED SEA 30 THE WARMEST BODY OF WATER With an area of nearly 440,000 km2 square, the Red Sea has the warmest deep-sea waters of any sea or ocean, reaching 21°C at a depth of 2,800m.
32 MANY OUTLOOKS ON THE RED SEA’S FUTURE The future of the Red Sea will be different to its past as it begins to experience the impacts of a changing climate. A broad approach is needed to understand how the Red Sea can adapt.
34 MICROBIAL COMMUNITIES HAVE A SEASONAL SHAKE-UP Turbulence and nutrient availability drive changes in Red Sea microbes.
35 GIANT BACTERIA MAKE ALGAE EASY TO STOMACH Symbiotic giant bacteria enable Red Sea surgeonfish to specialize their diets.
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Emerging technologies are poised to transform Wind suspended high howturbines we observe the in the sky have potential as an Earth. alternative power source for Saudi Arabia.
36 CAN CORAL REEFS CHANGE WITH THE TIMES? Coral ecosystems may be able to adapt rapidly to climate change through natural plastic responses.
38 HELPING CORALS TO COPE WITH PRESSURE When faced with high salinity, the tiny plant cells within coral tissue alter their metabolites to better cope with stress.
ADVANCING HUMAN HEALTH 40 HERBAL MEDICINE SHOWS POTENTIAL TO TREAT CANCER Herbal remedy plants native to Saudi Arabia are shown to have potential as treatments for cancer.
41 NANOPARTICLES TAKE A BITE OUT OF INFECTIONS Spiky-shaped additives help antimicrobial coatings sense and inhibit bacteria growth on dental devices.
42 THE HIDDEN ORDER IN DNA DIFFUSION The movement of DNA molecules seemingly explained by random motion conceals a more orderly march.
43 SHAPING UP AGAINST PATHOGENS Plants can reprogram their genetic material to mount a defensive response against pathogens, which may have applications for agriculture.
SMART MATERIALS 44 A BETTER WAY TO REMOVE WATER FROM GAS A breakthrough in generating water-stable metal-organic frameworks allows efficient removal of water from gases.
45 A SIMPLE NOSE FOR NOXIOUS GASES Tunable porous MOF materials interface with electrodes to sound the alarm at the first sniff of hydrogen sulfide.
is published for the King Abdullah University of Science and Technology (KAUST) by the Partnership and Custom Media Unit of Nature Research, part of Springer Nature. King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 – Kingdom of Saudi Arabia email: discovery@kaust.edu.sa web: www.kaust.edu.sa Nature Research The Campus – 4 Crinan Street – London, N1 9XY, UK email: nature@nature.com web: www.nature.com
46 LOOKING BOTH WAYS FOR NEW-STYLE SEMICONDUCTORS Introducing asymmetry across the two sides of atomically thin materials brings new opportunities in semiconductors.
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ABOUT THE COVER
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A new computational framework marries ideas from computer graphics with civil engineering to reduce times and costs of constructing frame-based structures.
48 KEEPING THE HEAT OUT
50 A NEW ENERGIES IN GAS SENSING
Insights into the thermal behavior of metal-nitride nanowires could open new avenues in optical electronics.
An ultrathin semiconducting sheet showing gasresponsive electronic properties may lead to highly sensitive gas sensors.
51 SEMICONDUCTORS WITH AN ALIGNED INTERFACE
52 USING SUNLIGHT TO THE MAX
Efficiency gains come from tuning the properties of semiconducting materials by combining layers of different composition.
A floating membrane that uses sunlight to evaporate water shows potential for water purification.
The whale shark is the largest known fish species: the biggest specimens are more than 14m long and weigh more than 20t. These are slow-moving creatures that live predominantly in open seas of the tropics and travel long distances to feed on plankton. Whale sharks aggregate at certain times of the year—the exact purpose of these gatherings is unknown. About a dozen aggregation sites have been documented worldwide. In the Red Sea aggregation, whale sharks were found to be mostly juveniles that were transient visitors. One KAUST project is sifting through large amounts of genomic data to better understand social structures of whale shark aggregations. KAUST is also investigating how these fish maintain high levels of energy when they dive as deep as 200m to feed. Each whale shark has a unique set of stripes and spots that enables researchers to identify individuals.
COVER CREDITS: Image photographed by Tane Sinclair-Taylor Design by: Amr Rahma
INNOVATION THROUGH VISUALIZATION 54 VISUALIZATION HELPS SCIENCE TO SEE THE UNEXPECTED Advances in how science is presented means that visual tools can inspire research, as well as make its results accessible to the world.
60 GAZING INTO THE FLAMES OF IONIC WINDS New 3D visualizations that reveal how flames respond to electric fields could help improve combustion efficiency and reduce pollution.
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56 STREAMLINING SPACE STRUCTURES A new computational framework marries ideas from computer graphics with civil engineering to reduce times and costs of constructing frame-based structures.
58 NO STRINGS ATTACHED FOR UNDERWATER VIDEO SYSTEM An underwater wireless optical communications system for streaming high-quality, live video.
59 3D PARTICLE TRACKING? THERE’S AN APP FOR THAT Smartphones put state-of-the-art 3D particle tracking in the hands of the masses.
THE POWER OF WATER 61 SUNNY SOLUTION FOR KILLING E. COLI
62 MARINE RESERVES OFFER PROTECTION
Treating wastewater with solar irradiation shows promise in reducing two E. coli strains but a resilient strain persists.
Protection zones for coasts and oceans are an effective way to help marine and human communities to adapt to climate change.
64 SPLITTING WATER FOR THE COST OF A NICKEL A simple treatment of nickel to make it an efficient catalyst for water splitting.
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Making greater use of the abundant sunlight as an alternative and sustainable power source is a priority for researchers worldwide. KAUST experts are working on solar energy conversion through interdisciplinary research to produce economically viable opportunities.
ENERGY FOR THE WORLD Learn more DISCOVERY.KAUST.EDU.SA
Sifting through huge amounts of data may bring better understanding of whale shark social structures, protein targets for drug therapies and diseasecausing genes.
THE AW E SOME SCOPE OF BIG DATA 6
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C E M S E Anyone looking for answers on personalized medicine, human health, food production, the environment or ecology will turn to big data, says James Calvin, vice president of academic affairs at KAUST; “Big data is a concept that permeates all of the biological sciences.” Researchers at the University’s Computational Bioscience Research Center work at the intersection of computer science and biology to sift through huge amounts of biomedical and biotechnological data. Their work, and that of international colleagues, could give clues to some major questions in the life sciences. “In the last 10-15 years, technological breakthroughs have allowed us to produce more and more data,” says computer scientist Robert
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Hoehndorf. To put things in perspective, he says, tens of thousands of papers have been published on diabetes, producing large amounts of research data that are uploaded to databases; however, “How can we connect all these different research results to provide a big picture?” he asks. Integrating this data could allow a better understanding of disease, guiding researchers toward potential treatments. Hoehndorf ’s main area of interest is the field of symbolic artificial intelligence (AI), which explores how to make machines that are similarly intelligent to humans. AI systems are being used to study health problems and to do biomedical research, he explains. In the area of big data, these systems are being used to integrate huge amounts of data and identify consistencies and contradictions within them. Hoehndorf and colleagues developed a computational method that allows the integration of data on tens of thousands of observable disease characteristics in yeast, fish, worms, flies, mice and humans. The method, called PhenomeNet, computes similarity between two sets of phenotypes—observable characteristics that result from the interactions of genes with the environment. This can help suggest genes that might underpin disease. Focusing on a different target, computational scientist Xin Gao is interested in developing computational models and machine-learning techniques to analyze protein structures, determine what they look like three-dimensionally, how they function, and how their behaviors can be controlled in complex biological networks. “I do not know the answer to whether big data can directly solve our health problems, but I do know with certainty that if these problems can be solved, then big data will be a part of the solutions,” says Gao. Mining huge amounts of data from pharmaceutical studies can help drug development, for example, says Gao. “Drug development is an extremely expensive and time-consuming process. It routinely takes pharmaceutical companies tens of years and billions of dollars to develop one single drug. The failure rate for drug development is extremely high,” he explains. Huge amounts of computational and experimental data are generated as a result of this process. “Instead of throwing this data away after a drug has been developed, it makes a lot of sense to develop computational methods to effectively mine some knowledge and important information and hopefully reuse it in the development of future drugs.” Gao and colleagues developed a combined approach1 involving nuclear magnetic resonance spectroscopy, single-molecule fluorescence resonance energy transfer, and molecular dynamics simulation to investigate the dynamic interactions between proteins that lack fixed 3D structures. “In
reality, proteins are not rigid bodies. They have certain dynamics and kinetics in our body. In order to better find the correct matching between drugs and [targeted] proteins, you have to take such conformational changes into consideration,” he says. Thanks to the Shaheen II supercomputer at KAUST, rated as the 15th fastest computer in the world, Gao’s team can conduct many molecular dynamics simulations on target proteins as they endeavor to make more reliable predictions for drug development. Bioscientist Takashi Gojobori, aims to elucidate the evolutionary origin of the neural network and its application to synthetic biology for developing bioenergy. Gojobori has also used big data with colleagues Gao, Hoehndorf and other international scientists. Together they developed a computational screening method2 that evaluates the potential of bacterial strains to produce free fatty acids that can act as precursors for energy-dense biofuels. More recently, Gojobori has been sequencing the genomes of Red Sea whale sharks. In collaboration with marine scientist Michael Berumen, Gojobori is sifting through huge amounts of genomic data that will shed light on the social structures of whale sharks travelling in groups. The two researchers are also interested in understanding how these mammals maintain high levels of energy when they must dive as deep as 200m to feed.
“B i g d a t a i s a c o n c e p t that permeates all of the biological sciences.” Gojobori has also co-authored studies with Emperor Akihito of Japan, who is a published researcher in fish science. Together, they have been analyzing nuclear and mitochondrial genes belonging to gobioid fish in order to understand how new species of these fish evolved as a result of geographical differentiation. 1. Wu, S., Wang, D., Liu, J., Feng, Y., Weng, J., Li, Y., Gao, X., Liu, J. & Wang, W. The dynamic multisite interactions between two intrinsically disordered proteins. Angewandte Chemie 56, 7515–7519 (2017). 2. Motwalli, O., Essack, M., Jankovic, B.R., Ji, B., Liu, X., Ansari, H.R., Hoehndorf, R., Gao, X., Arold, S. T., Mineta, K., Archer, J.A., Gojobori, T., Mijakovic, I. & Bajic, V.B. In silico screening for candidate chassis strains of free fatty acidproducing cyanobacteria. BMC genomics, 18, 33 (2017).
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DATASET SIZE COUNTS FOR BETTER PREDICTIONS A statistical technique for modeling large datasets improves interpretation of climate and environmental data.
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C E M S E A new statistical tool for modeling large climate and environmental datasets that has broad applications—from weather forecasting to flood warning and irrigation management—has been developed by researchers at KAUST. Climate and environmental datasets are often very large and contain measurements taken across many locations and over long periods. Their large sample sizes and high dimensionality introduce significant statistical and computational challenges. Gaussian process models used in spatial statistics, for example, face considerable difficulty due to the prohibitive computational burden and rely on subsamples or analyze spatial data region by region.
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Ying Sun and her PhD student Huang Huang developed a new method that uses a hierarchical lowrank approximation scheme to resolve the computational burden, providing an efficient tool for fitting Gaussian process models to datasets that contain large quantities of climate and environmental measurements. “One advantage of our method is that we apply the low-rank approximation hierarchically when fitting the Gaussian process model, which makes analyzing large spatial datasets possible without excessive computation,” explains Huang. “The challenge, however, is to retain estimation accuracy by using a computationally efficient approximation.” Traditional low-rank methods are usually computationally fast, but often
inaccurate. The researchers, therefore, made the low-rank approximation hierarchical, ensuring that the covariance matrix used to fully characterize dependence in the spatial data is not low rank: this makes it is as fast as traditional methods while significantly improving the accuracy. To evaluate their model’s performance, they undertook numerical analysis and simulations and found the model performs much better than the most commonly used methods. This ensures that credible inferences can be made from real-world datasets. The model was applied to a spatial dataset of two million soil-moisture measurements from the Mississippi River basin in the United States. They were able to fit a Gaussian process model to understand the spatial variability and
predict values at unsampled locations. This led to a better understanding of hydrological processes, including runoff generation and drought development, and climate variability for the region. “Our research provides a powerful tool for the statistical inference of large spatial data, says Sun. “And when exact computations are not possible, environmental scientists could use our methodology to handle large datasets instead of only analyzing subsamples. This makes it a practical and attractive technique for very large climate and environmental datasets.” Huang, H. & Sun, Y. Hierarchical low rank approximation of likelihoods for large spatial datasets. Journal of Computational and Graphical Statistics (2017).
The model was applied to a spatial dataset of the Mississippi River basin in the United States to improve understanding of hydrological processes and climate variability.
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David Keyes stands with the supercomputer Shaheen II, which underpins the collaboration by providing high-performance computing applications and strategic advice and support.
CUTTING DATASETS DOWN TO SIZE C E M S E By exploiting the power of high-performance computing, a new statistical tool has been developed by KAUST researchers that could reduce the cost and improve the accuracy of analyzing large environmental and climate datasets. Datasets containing environmental and climate observations, such as temperature, wind speeds and soil moisture, are often very large because of the high spatial resolution of the data. The cost of analyzing such datasets increases steeply as the size of the dataset increases: for instance, increasing
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the size of a dataset by a factor of 10 drives up the cost of the computation by a factor of a 1,000 and the memory requirements by a factor of 100, creating a computational strain on standard statistical software. This spurred postdoctoral fellow Sameh Abdulah to develop a standalone software framework through a collaboration between KAUST’s Extreme Computing Research Center (ECRC) and statisticians specializing in spatio-temporal dynamics and the environment. The new framework, called Exascale GeoStatistics or ExaGeoStat, is able to process large geospatial environmental
and climate data by employing highperformance computing architectures with a high degree of concurrency not available through universally used statistical software. “Existing statistical software frameworks are not able to fully exploit large datasets,” says Abdulah. “For example, a computation that would normally require one minute to complete would take nearly 17h if the dataset were just 10 times larger. This leads to compromises due to the limitations in computing power, forcing researchers to turn to approximation methods that cloud their interpretation of results.” Leveraging linear algebra software developed by the ECRC, ExaGeoStat
KAUST / ANASTASIA KHRENOVA
A powerful statistical tool could significantly reduce the burden of analyzing very large datasets.
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provides a framework for computing the maximum likelihood function for large geospatial environmental and climate datasets. It is able to predict unknown or missing data as well as reduce the effect of individual measurement errors, allowing the data to be easily analyzed and represented in a statistical model used for making predictions. The researchers successfully applied ExaGeoStat to the same large, realworld dataset of soil moisture measurements from the Mississippi basin in the United States used by Huang and Sun (see pg. 8-9). This could lead to the routine analysis of the larger datasets that are becoming available to geospatial statisticians and could be used in a wide range of applications from weather forecasting, crop-yield prediction, and earlywarning systems for flood and drought.
KAUST
“It is able to predict unknown or missing data as well as reduce the effect of individual measurement errors” David Keyes, Director of the ECRC, which hosts the project, plans significant further improvements, tracking a rapidly developing technique in linear algebra: “We are now working on taking ExaGeoStat a step further on the algorithmic side by introducing a new type of approximation, called hierarchical tile low-rank approximation, which reduces memory requirements and operations by allowing for small errors that can easily be understood and controlled.” Abdulah, S., Ltaief, H., Sun, Y., Genton, M.G. & Keyes, D.E. ExaGeoStat: a high performance unified framework for geostatistics on manycore systems. arXiv:1708.02835v2 [cs.DC] (2017).
BRINGING SIGNALS INTO PHASE A novel type of electronic component made from a blend of polymer materials could enable more effective circuitry.
C E M S E How we use and generate electricity has changed dramatically over the past century although the basic components that control its flow remain remarkably similar. Researchers at KAUST have now developed a novel type of component that could improve the performance of electrical circuits. Electronic circuitry is traditionally constructed from three primary elements; a resistor, a capacitor and an inductor. A sinusoidal electrical signal passing through these devices will change in signal strength, or amplitude, and the relative timing of the crest of the wave, known as its phase. A resistor will change amplitude only while a capacitor and an inductor can also change phase, but only by exactly one quarter of the length of the wave, or 90°. Components that could alter the phase of the electrical signal by a different amount would enable electrical circuits with more varied functionality. One such device, known as a fractional-order capacitor, was realized by electrical engineering doctoral student Agamyrat Agambayev, under the
Blending polymer materials in the right combination can create fractionalorder capacitors that are compatible with printed circuit boards.
supervision of Hakan Bagci and Khaled Salama, and colleagues. “We use a solution-casting method to fabricate fractional-order capacitors,” explains Salama. “This method allows us to easily blend different polymers and provide a mechanism to tune the device’s properties.” Numerous approaches to creating a fractional-order capacitor have been demonstrated in the past but all have drawbacks. Ideally, a fractional-order capacitor should be made from a dielectric material that is compatible with printed-circuitboard technology. It should also operate over a wide range of signal frequencies and have a controllable phase change, known as the constant phase angle or CPA. The KAUST team have created a fractional-order capacitor using a polymer based on polyvinylidene fluoride. They deposited a thin film on a layer of gold on a silicon substrate. The film was patterned as required and bonded to the printed circuit board to create the final device. The electrical properties of the polymer were controlled using a simple solutionmixing approach to add different amounts of trifluoroethylene and/ or cholorfluroethylene. They could tune the CPA of their devices from between 66 and 88° depending on the blend composition. What’s more, the devices acted over a wide range of frequencies from 0.1 to 10 megahertz. The team has previously created graphene fractional-order capacitors, but they believe the tunablility offered by polymers represents a huge advance. “Next, we will look into modeling these structures to better understand their behavior,” says Bagci. Agambayev, A., Patole, S. P., Farhat, M., Elwakil, A., Bagci, H. & Salama, K. N. Ferroelectric fractional-order capacitors. ChemElectroChem 4, 28072813 (2017).
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SMART SENSORS COULD SAVE LIVES 3D-printed, disposable sensors capable of detecting noxious gases and changes in temperature and humidity could revolutionize environmental monitoring.
that are linked wirelessly to fewer fixed nodes that raise the alarm. Shamim sees this as part of a drive toward an internet of things, “Where infrastructure makes smart decisions in place of humans.” This proof-of-concept study designed small sensors that can pick up heat and low humidity, both hallmarks of forest fires, as well as hydrogen sulfide, a toxic industrial gas. These small sensors were inkjet-printed onto a 3D-printed, 2-cm3 node containing a battery and microelectronic circuit board along with an antenna that transmits in any direction. Shamim says they adopted 3D and inkjet printing, “the next revolution in industrial manufacturing” because they
are additive processes, making them fast, low-cost and environmentally friendly. “Material is deposited in precise quantities only at the desired location,” he explains. “Traditional manufacturing methods take bulk material and gradually remove material to realize the final shape, resulting in significant wastage.” Designed by PhD student Muhammad Farooqui, the node has been tested in both lab and field. It survives being dropped from a height and subjected to temperatures up to 70ºC, which, says Shamim, “is good enough to give an early warning in cases of wild fire.” He believes it is the first “lowcost, fully integrated, packaged, 3D-printed wireless
AMR RAHMA/ PARTNERSHIPS & CUSTOM MEDIA NATURE RESEARCH REPRODUCED WITH PERMISSION FROM REF 1.© FAROOQUI ET AL.
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C E M S E In an emergency, early warning is key to escaping from a hazard, such as a forest fire or a chemical leak. Motivated to improve on safety, a team from KAUST is using 3D printing to develop a cheap, reliable system to signal danger. Existing early warning systems rely on satellite monitoring, watch towers or expensive fixed sensors. The system, developed by a team led by Atif Shamim, works by saturating high-risk areas with disposable packages of sensors (sensor nodes)
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Real-time environmental monitoring Few fixed sensor nodes and many low cost, mobile wireless sensors to monitor large areas Inkjet manufacturing and cheap materials Early warnings in cases of fires and industrial leaks Fully integrated, packaged, wireless sensor to monitor temperature, humidity and gas levels.
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Shamim sees this as part of a drive toward an internet of things, “where infrastructure makes smart decisions in place of humans.”
sensor node for real-time environmental monitoring.” Currently the nodes are built using a combination of 3D and inkjet printing because no 3D printer can accurately deposit all the materials into the complex design. However, they will soon be made by a single machine, which will drastically reduce manufacturing time. The next step is to incorporate an energy source, making the nodes self-sustainable in remote locations. “Inkjet-printed solar cells
KAUST scientists’ disposable mobile wireless sensor nodes can be used to give early warning of industrial leaks or forest fires. 1 2
1 Inkjet Antenna
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2 Inkjet CNT Gas Sensor 3 Inkjet PEDOT:PSS Temperature Sensor
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4 Inkjet PEDOT:PSS Temperature Sensor
have already been demonstrated,” Shamim enthused. “Eventually we want to get rid of the battery entirely.” Removing the battery, together with scaling up manufacture and mass-producing customized chips in place of the circuit board, will take the cost of each sensor node below a dollar—a small price to pay for a technology that could save hundreds of thousands of lives. Farooqui, M.F., Karimi, M.A., Salama, K.N. & Shamim, A. 3D-printed disposable wireless sensors with integrated microelectronics for large area environmental monitoring. Advanced Materials Technologies 2, 1700051 (2017).
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VALLEY POLARIZATION GETS A MAGNETIC BOOST Access to valley-polarized charge carriers by magnetic doping could transform electronics.
P S E The field of valleytronics is emerging as a way of exploiting specific energy extrema known as valleys. This field has the potential to revolutionize conventional electronics, which rely on the control and manipulation of charged particles, such as electrons and holes, and surpass the capacity of spintronics, which depends on the intrinsic spin property of particles. Valleytronics is based on the crucial trapping of charge carriers in energy valleys; however, device development is hindered by the complexity involved with the necessary valley polarization. Several researchers have generated valley polarization in semiconductors called transition-metal
From left to right: Professor Younis and PhD students Nizar and Saad examine a silicon chip before placing it into an environmental chamber for further electrical probing and testing.
GOOD VIBRATIONS FOR THE FUTURE OF COMPUTING A vibration-driven logic gate could form the basis for the next generation of efficient, low-power computers.
dichalcogenides but the effectiveness of this approach has been hampered because it demands sustained optical pumping, which requires light to pump electrons to a higher energy state. “This problem can be eliminated by creating a
P S E
are connected to much larger
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To test this hypothesis, Schwingenschlögl and research
metal sheet sandwiched between two sulfur sheets. The researchers’ first option for a magnetic dopant
The microcomputer processors found inside
computing into the future. Saad Ilyas and Nizar
was chromium, which presents the same electronic
every computer, mobile
Jaber, doctoral researchers
configuration as molybdenum. They chose this dopant
phone and microwave
in the laboratory of
thinking it might induce spin polarization—a state in
comprise mind-bogglingly
Mohammad Younis, have
which all spins are oriented in the same direction—and
complex networks of millions
now demonstrated a scalable,
promote valley polarization. But, instead of the desired
or billions of microscopic
efficient alternative technology,
effect, the team observed a complex magnetic structure.
transistors—electrical
not based on electrical current,
According to Schwingenschlögl this surprising
switches that turn on when
but on mechanical vibrations
extended-moment formation counteracts the valley
a current flows across their
excited by multifrequency
polarization. The team experimented with vanadium-
terminals. These transistors
electrical inputs.
doped single-layer MoS2 to find that the resulting
are networked together to
“Electromechanical
material exhibited permanent valley polarization.
construct logic gates that
systems offer a major
perform operations, such as
advantage over existing
Singh, N. & Schwingenschlögl, U. A route to permanent
AND (when two inputs are on)
technology in that they
valley polarization in monolayer MoS2. Advanced
and OR (when either input is
are leakage free: that is,
Materials 29, 1600970 (2017).
on). In turn, these logic gates
unlike electrical transistors,
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they only consume power when switched,” explains Ilyas. “They also require fewer gates per computing
TINY SPEAKERS BREAK A BARRIER FOR SOUND
be fabricated with higher integration densities—it is
A loudspeaker design could allow small devices to produce powerful low-frequency sounds.
enclosure made from high-density The air channels reduce the overall speed of the sound, which enhances low-frequency sounds and suppresses higher sounds.
even predicted that these
“Through the resonance of the air
systems could be scaled
C E M S E
inside the channels, a lot more of the
systems (MEMS) have been
In any orchestra, the lowest notes
to sound power than would otherwise
investigated in the past for
are made by the largest instruments;
be the case,” explains Wu.
logic operations, but it has
for example, in the string family, the
been a challenge to devise a
double bass resonates much lower
showed that the enclosure not only
mode of operation that allows
notes than the violin because it is four
enhanced low sounds but also emitted
the MEMS logic gates to be
to five times larger. The same is true for
powerful sound in all directions around
cascaded to form arbitrary
loudspeakers. Large speakers, known
it. This overcomes another limitation of
computational functions.
as woofers, are required to produce
traditional loudspeakers, which tend to
Jaber and Younis have come
clear bass notes while small speakers,
emit sound in only one direction.
up with a novel technique
like those in mobile phones, produce
to perform logic operations
high tinny noises that don’t do justice to
coworkers to build and test a real
using MEMS based on
recorded music.
version of their enclosure design. “When
down to the molecular level.” KAUST
a sound source in a ring-shaped brass with coiled air-filled channels.
function, resulting in lower complexity, and they can
The structural resonances proposed by the researchers involve putting
Microelectromechanical
frequency mixing, which holds
electric power of the source is converted
Jiajun Zhao and Ying Wu from KAUST,
Computer simulations of this design
The next step was for Zhao and
a cell phone source is enclosed by the
with coworker Likun Zhang at the
structure, more than 200 times the
University of Mississippi, have proposed
sound power is emitted than when the
as an input, which causes a
a new miniaturized device that can emit
structure isn’t there,” says Zhao. “We
clamped polymer microbeam
deep, powerful sounds using so-called
are happy to see that our design doesn’t
to vibrate at a certain
subwavelength technology.
just work on paper but also in reality.”
great potential for cascading. “We use an electrical signal
resonance frequency,” says
“A traditional audio setup combines
Now finished his postdoctorate, Zhao
Jaber. “This in turn generates
small loudspeakers for high frequencies
will soon move to work in the energy
motional current as an
and large woofers for low frequencies,
industry in Houston, but he is very
electrical signal with the same
which is bulky and clumsy,” says Zhao.
grateful for his time at the university.
frequency, which could then
“We use structural resonances to build
“Being at KAUST is a unique
be cascaded into the input of
a miniaturized loudspeaker system that
experience,” he says. “I learned a
another MEMS logic gate.”
works as well as traditional ones.”
lot from my supervisor Dr. Wu, who provided valuable advice not only
The team demonstrated various logic operations at a single operating frequency, which is an important step towards cascading as the next milestone in MEMS resonator-based computing.
Schematic of the enclosure designed to change the environment around a sound source. The enclosure greatly enhances the power of lowfrequency sounds.
on my research but also my career development. Furthermore, the experts that are invited each year to KAUST to give seminars helped me to establish wide connections within the research community of my interest.”
Their logic gates are also compatible with existing
Zhao, J., Zhang, L. & Wu, Y.
fabrication techniques.
Enhancing monochromatic multipole emission by a
Ilyas, S., Jaber, N. & Younis,
subwavelength enclosure of
M.I. MEMS logic using mixed-
degenerate Mie resonances.
frequency excitation. Journal of
The Journal of the Acoustical
Microelectromechanical Systems
Society of America 142, EL24
26, 1140-1146 (2017).
(2017). K AUST DISCOVERY
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BREAKING NEW GROUND
PHYSICS FORECASTS FOR FRACKING AND FUELS Physicists are playing unexpected roles in meeting future global energy challenges by modeling technologies such as fracking. P S E Society’s demand for energy relies mainly on oil and gas, which are finite resources. Future technologies could reduce the consumption of energy, but until then, existing resources must be carefully managed. Director of the Ali I. Al-Naimi Petroleum Engineering Research Center at KAUST Tadeusz Patzek is using physics to tackle this challenge by modeling the production of gas from fracking. Patzek and his coworkers describe two visions of global energy consumption. Optimists believe that human population, energy use and economies can continue to grow exponentially because humans will keep inventing innovative ways to survive. Others, however, note that the Earth imposes clear limits on growth, meaning that energy production will peak before tailing off. Oil and gas production has indeed reached peaks in the past, but these have been usurped by discoveries of new reserves and technologies for extracting fuels from previously
TRANSFORMING HOW WE THINK ABOUT SOILS— FROM THE GROUND UP A new soil classification system, and tools to implement it, helps understanding of the properties of the ground underpinning geoengineering projects. 16
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inaccessible areas. The most complex and controversial new process is fracking (hydraulic fracturing) of ancient ocean beds called shale formations. Fracking involves injecting high-pressure water and sand into shale layers several kilometers underground, producing cracks that release trapped hydrocarbons.
P S E While most of us take soils for granted, researchers from KAUST’s Energy GeoEngineering Laboratory literally know soils inside out. Their research has important implications for diverse geotechnical projects, including mining, oil extraction, bridge and tower foundations, coastal and offshore structures, analyzing tunnels and sinkholes, and designing earthquakeresilient infrastructure. Professor J. Carlos Santamarina, postdoc Junbong Jang (now at the United States Geological Survey) and PhD student Junghee Park have designed a new classification system for the world’s
soils that will enable engineers to predict more accurately their properties and behavior based on simple metrics. At present, most of the world’s geotechnical studies use the Unified Soil Classification System (USCS), which has its roots in the construction of World War II airfields. Since then, it has been refined, but not fully updated. Meanwhile, soil data have accumulated extensively and, Santamarina explains, “led to a deeper understanding of sediment properties and behavior,” suggesting the need for a thorough re-evaluation of the system.
A new state of matter We tend to consider matter to be solid,
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condensed-matter physics, such as those governing electron transport at low temperatures. Their resulting model requires very few parameters to model the diffusion of gas out of fracking wells, and the researchers validated it by accurately predicting the output of 14,000 gas wells in the US. Overall, the study showed that only 10-20% of natural gas in fracking fields is being extracted with today’s techniques. This suggests that, while technical improvements could prolong the lifetime of fracking as a useful fuel source, the flood of gas predicted by some industrialists is not yet guaranteed.
“I am also an avid environmentalist, and from this perspective, we need to change our way of business.” Patzek will not state whether he is an optimist or a pessimist regarding fracking. “I am neither,” he says. “I am a scientist, and my outlook on nature is governed strictly by the chemistry and physics of the processes at hand. However, I am also an avid environmentalist, and from this perspective, we need to change our way of business.” Patzek and coworkers have certainly shown that physicists have a role in developing new business models for future energy sources.
“My coauthors, Scott Tinker and Michael Marder, and I, worked on a Sloan Foundation project, whose goal was to model gas recovery from shales in the US in unprecedented detail,” says Patzek. Instead of applying existing gas-well simulations, which are complex and time-consuming to run, the researchers were inspired by the elegant, simple models of
Marder, M., Patzek, T., & Tinker, S.W. Physics, fracking, fuel and the future. Physics Today 70, 13-14 (2017).
2017 J. CARLOS SANTAMARINA
TADEUSZ PATZEK
To generate sand slurry requires a low-pressure manifold to mix water and polymer with sand.
The remarkable range of sizes and shapes found in soil particles has been captured in the new classification system.
liquid or gas. However, particulate materials, such as soils, may act differently to any of these states. Santamarina describes soils, enigmatically, as “inherently nonlinear, nonelastic, porous,
pervious and effectively stress dependent.” The USCS defines soil types by particle size and plasticity, or how they deform when mixed with water. However, soils can comprise complex
mixtures of differently sized particles, and furthermore spaces between particles are not empty but filled with liquid, gas or both. Santamarina enthuses, “The coexistence of these
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BREAKING NEW GROUND
Get social with KAUST Follow us on social media KAUSTofficial @kaust_news kaustedu kaustofficial
materials gives rise to fascinating emergent phenomena and puzzling responses, such as liquefaction.” The new revised soil classification system1,2 takes into account not only grain size but shape and provides a more accurate representation of the transition zones between soil types. It places more importance on the role of the smallest soil particles, known as fines, and the chemistry of the surrounding fluid, which influences many geotechnical phenomena. Crucially, the new classification system enables engineers to distinguish the soil fraction that is primarily responsible for carrying any weight placed upon them and the soil fraction that controls the flow of fluid.
“The coexistence of these materials gives rise to fascinating emergent phenomena and puzzling responses, such as liquefaction.” Soil classification is a relatively simple process of determining a set of parameters using bench-top devices readily available in soil laboratories worldwide. These can then be entered into the equations detailed in the team’s publications, or analyzed using a spreadsheet or cell phone app, both available on their website. The result, for any given soil, is a two-part description incorporating both mechanical and fluid-flow properties; for example, ‘S(F)’ signifies a soil with mechanical properties controlled by sand, but with permeability determined by its fines component.
An ongoing endeavor Response to the publication of
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the revised classification has been encouraging and collaborative. When the team published the first part, covering fines, “researchers from around the world reacted and contributed exceptional data to strengthen the classification,” says Santamarina. “We expect a similar response to the second part.” He continues, “The reality of soils is more complex than the idealized systems created in the lab or on a computer.” A complementary soil database built at KAUST enables users to make robust estimates of the hydromechanical properties of natural soils. In fact, the researcher in Santamarina’s laboratory is geared toward a continuously evolving set of engineering analysis and design tools. The classification, says Santamarina, is just “a first step toward an integrated laboratory-database-IT system being developed with collaborators worldwide.” No classification can be exhaustive: soils made of uncommon grains, such as diatoms or fly ash, will always present special challenges that engineers need to be aware. However, the classification aims to be robust enough to be used successfully even by those without field experience. The team is currently working on a publication that will extend the application and interpretation of the classification in practice. This multidisciplinary work—drawing on concepts from geology, physics and chemistry and oriented at disciplines from civil to environmental and energy geo-engineering—benefits from what Santamarina calls the exceptional research environment and expertise available at KAUST to generate tools with applications much further afield. 1. Park, J. & Santamarina, J.C. Revised soil classification system for coarsefine mixtures. Journal of Geotechnical and Geoenvironmental Engineering 143, 04017039 (2017). 2. Jang, J. & Santamarina, J.C. Fines classification based on sensitivity to pore-fluid chemistry. Journal of Geotechnical and Geoenvironmental Engineering 142, 06015018 (2016).
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THE SKY’S THE LIMIT FOR EARTH OBSERVATION Emerging technologies are poised to transform how we observe the Earth.
“One of the most exciting aspects of working in Earth observation currently Imagine sending your own custom- is that the technology is cutting-edge,” made satellite into space to study specific says McCabe. “It is one of those rare elements of rivers, glaciers, volcanoes, instances where technology is not a landslides or agricultural practices. constraint on scientific thought. In the Sensors, digital imaging and other past, we generally had to compromise sensing components have shrunk in between how well we could observe the size and cost, which has dramatically earth, and how often. With advances changed the technology available to in sensors and systems, these spatioEarth scientists in just the last five years. temporal divides are gradually being KAUST researchers and international removed. The potential for new research, colleagues report that we are enter- applications and insights is huge, and is ing a new era in Earth observation and restricted only by our imagination!” research; and they identify what’s needed From the workshop came a paper, led by McCabe, that serves as a techif we are to maximize its opportunities. In 2016, Matthew nological roadmap for future McCabe met with experts students and researchers. A A quadcopter hovers from across the globe for a wide range of research posabove a paddock. A workshop at Princeton Unisibilities are canvassed: from practical outcome versity, USA, to examine harnessing and analyzing of this technology the current state of Earth big data captured by satelis affordable, farmobservation. They discussed lites and unmanned aerial scale aerial systems vehicles (UAVs), to moniexisting and emerging techthat offer real time toring events such as flash nologies and how these might monitoring of crops be utilized in the near future. for farmers. floods using high resolution,
MATTHEW MCCABE
B E S E
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real-time video. A future of stratospheric balloons, continuous monitoring by solar planes and a global coverage of internet-enabled devices are reshaping how we observe and monitor the Earth. While government space agency programs already contribute greatly to Earth observation, McCabe also highlights the value of working with burgeoning smaller-scale, commercial organizations. Currently he works with the private American company Planet, which creates custom-made shoe-boxsized satellites equipped with miniaturized sensors at a fraction of the cost of space agencies. These budget satellites have the potential to fill gaps in current knowledge and enhance the available spatial and temporal coverage: Planet’s satellites, or ‘CubeSats’, can take multiple high-resolution snapshots of the Earth surface, at almost daily repeat times.
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“The potential for new research, applications and insights is huge, and is restricted only by our imagination!” “With cost-reductions brought about by reusable rockets, individual investigators can realistically launch their own CubeSat! I’d love to put a KAUST satellite into space,” says McCabe. “Our most recent research uses UAVs to monitor the health of crops across farmers’ fields. Feasibly, we’re looking at affordable, farm-scale aerial systems that can tell the farmer precisely which parts of his crops
need irrigating and when, the state of the crop in terms of disease, and many more elements, all in near real-time. Combining UAVs with the global coverage of these small satellites could revolutionize agricultural practices around the world.” But all these new technologies present new challenges: not least is the computational power needed to analyze and interpret the big data that these devices collect. “We must train the next generation of Earth and environmental scientists to embrace the computational challenges inherent in big data — it’s not just raw computing power, we need machine learning and big data analytics tools that can interrogate the vast information reserves of this collected imagery,” says McCabe. This remotely sensed data needs validation by equally strong sensing systems on the ground. Existing groundbased observation systems should be boosted with novel technologies that improve rainfall and stream-flow measurements, for example, or monitor realtime weather conditions during storms. Researchers should also leverage the internet of things, developing smart networks and heightening connectivity. One example is to engage the power of smartphones and encourage the public to get involved in citizen science—a recent KAUST research project used a smartphone app to collect data on temperature and humidity in crowded spaces. “Combining forces is the key—both in terms of the people we work with in research and the different levels of technology,” says McCabe. “It is a formidable jigsaw to put together, but I’m confident that we’ll rise to the challenge. We have a unique opportunity to reshape the nature of Earth observation, merging sophisticated tools and new data sources that can provide both real-time monitoring and deep scientific insights into the Earth and its processes.”
2017 HYDROLOGY AGRICULTURE AND LAND OBSERVATION TEAM
BREAKING NEW GROUND
McCabe, M., Rodell, M., Alsdorf, D.E., Miralles, D.G., Uijlenhoet, R. et al. The future of Earth observation in hydrology. Hydrology and Earth System Sciences 21, 3879-3914 (2017).
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KAUST / XAVIER PITA
An Earth-observing “system of systems” for revolutionizing our understanding of the hydrological cycle.
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Esma Urur and Frédéric Laquai make progress with developing high-quality perovksite thin films for use in solar cells.
A SIMPLE ADDITIVE TO IMPROVE FILM QUALITY P S E
Thin films for use in solar cells are more effective when simple chemicals called glycol ethers are added to the film-forming mix, a KAUST team has found. “This is an unexpected discovery,” says Esma Ugur, a PhD student in the KAUST Solar Center team that observed the effect. “It yields more uniform thin films with improved structure and efficiency.” Perovskites are materials with the
22
same crystal structure as the naturally occurring perovskite calcium titanium oxide. Various metal halide perovskites are proving useful for harvesting light energy that can then be used to create electric current—the basic operating principle of a solar cell. The perovskites can be added as a thin layer on top of conventional solar cells because they can harvest the blue wavelengths of light to complement the energy of red wavelengths captured by traditional materials. “Our aim was to improve the quality
of perovskite thin films,” says Ugur. The team decided to add glycol ethers to the manufacturing process because they knew these chemicals had previously been used to help create layers of metal oxides. By trying different glycol ether mixtures and conditions, the researchers eventually gained better control over the formation of their perovskite thin films because they were able to significantly improve the structure and alignment of the perovskite grains. This increased the reproducibility and efficiency of the
KAUST / FRÉDÉRIC LAQUAI
Simple chemicals called glycol ethers help make better perovskite thin films for solar cells.
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ENERGY SOLUTIONS
A KITE THAT MIGHT FLY Wind turbines suspended high in the sky have potential as an alternative power source for Saudi Arabia.
P S E Photovoltaic devices produced with the assistance of simple additives.
IMAGESOURCE
perovskites such that they performed more efficiently in solar-cell applications. The procedure also operates at lower temperatures than alternatives, which is an important factor in improving cost effectiveness. To date, the team have only made small lab-scale devices. The next key challenge, explains Frédéric Laquai, who leads the KAUST Solar Center team, is to scale this up for commercial applications. To achieve this, they will need to find ways to overcome the instability of their perovskites. “We have several groups in the KAUST Solar Center working on that issue and on other needs for future commercial development” says Laquai. He emphasizes that perovskites are a highpriority research area for the Center with potential for applications beyond just solar cells. “Perovskites have many interesting optical and electronic properties, which may make them useful for applications that we have not even thought about,” he explains. Laquai also highlights the collaborative character of the projects at the KAUST Solar Center. He cites the ability to draw on the expertise of specialists from several different fields as key factors contributing to their success.
The notion of tethered wind turbines that generate electricity from abundant and reliable highaltitude winds seems futuristic. Now, KAUST research led by Georgiy Stenchikov has identified the most favorable areas for highaltitude wind-energy systems in the Middle East. The results confirm that there is abundant wind energy up there that could feasibly be harnessed, bringing the possibility of highaltitude power generation a step closer. “We are very enthusiastic about taking this work forward,” says Udaya Gunturu, who studies atmospheric processes at KAUST. “Wind turbines on the Earth’s surface suffer from the very stubborn problem of intermittent wind supply,” says Gunturu. This has led researchers and
Researchers and energy companies are turning to the abundant wind resources at higher altitudes to explore the potential for using winds there to generate energy.
energy companies worldwide to look upwards and explore the possibilities of the strong and reliable winds at high altitudes. Flying a wind turbine on a kite— with the electricity being delivered to the ground through its tether— may seem an unlikely scenario, but several companies worldwide are already testing prototype systems. These developments attracted the attention of the Saudi Basic Industries Corporation (SABIC), which funded KAUST research to explore opportunities in the Middle East. The project made an excellent PhD topic for student Andrew Yip, first author of the research paper. The researchers used information on wind strengths at different altitudes that was already available from the US space agency NASA. They processed this raw data to identify the most favorable areas for airborne wind-energy systems, and the optimal heights at which the turbines would need to fly. They also factored in daily and seasonal variations. “Optimal altitudes for the turbines vary by region and with time of year and time of day,” says Yip. “In general, the abundance
Ugur, E., Sheikh, A.D., Munir, R., Khan, J. I., Barrit, D, Amassian, A. & Laquai, F. Improved morphology and efficiency of n-i-p planar perovskite solar cells by processing with glycol ether additives. ACS Energy Letters 2, 1960–1968 (2017).
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ENERGY SOLUTIONS
of the airborne wind-energy resources increases with altitude.” Tethered kites could potentially offer the flexibility to vary the altitude of the turbines as wind conditions change. Current technology would most likely allow harvesting wind energy at heights of 2-3km, but there is also a lot of wind even higher than that.
“Tethered kites could potentially offer the flexibility to vary the altitude of the turbines as wind conditions change.” The researchers conclude that the most favorable regions for high-altitude wind energy in the Middle East are over parts of Saudi Arabia and Oman. Their next step will be to increase the resolution of their study. “Our work may help Saudi Arabian wind-energy technology to leapfrog into the future and fulfill the Kingdom’s Vision 2030 plan on the development of renewable energy resources,” says Stenchikov. Yip, C. M. A., Gunturu, U. B. & Stenchikov, G. L. High altitude wind resources in the Middle East. Scientific Reports 7, 9885 (2017).
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A FIREFLY’S FLASH INSPIRES NEW NANOLASER LIGHT
Synchronized emissions from innovative on-chip lasers create possibilities for inexpensive artificial neural networks. C E M S E A reinvented, low-cost laser source that stores light energy inside nanoscale
disks could underpin the development of optically powered neurocomputers, reveals a simulation study led by KAUST researchers.
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KAUST / ANDREA FRATALOCCHI
Fratalocchi and his team were inspired by the complex flashing patterns of fireflies to develop ‘anapole’ lasers that use interactions between energy-storing nanodisks to generate high speed pulses of light on microchips.
Photonic devices that use controlled laser pulses to manipulate data switches, biomedical implants and solar cells are sought-after because they are lightning quick compared to traditional electronics; however, current prototypes have not been commercialized because of the difficulty in making lasers small enough to fit onto computer circuit boards, while also retaining pulse-shaping capabilities. “The challenge of reducing an optical source down to the nanoscale is that it starts to emit energy strongly in all directions,” explains KAUST’s Andrea
Energystoring nanodisks
Fratalocchi. “This makes it almost impossible to control.” A partnership with Yuri Kivshar’s group at the Australian National University revealed paths to beat optical
diffraction limits with unconventional anapole lasers. Being made from semiconductors shaped into precisely sized nanodisks, anapoles respond to light stimulation by producing electromagnetic waves that either radiate or rotate in donut-shaped toroid distributions. At specific excitation frequencies, interference between the two fields produces a state—the anapole—which does not emit energy in any direction and traps light inside the nanodisk. “You can think of this laser as an energy tank—once the laser is on, it stores light and doesn’t let it go until you want to collect it,” says Fratalocchi. To unlock the potential of this new light source, the team simulated various engineering architectures using quantum-based algorithms. These calculations, along with improved microchip integration and thousand-fold enhancements in coupling to optical routers, predict that anapole nanolasers can generate ultrafast light pulses that are uniquely suited for studying natural patterns of signaling and neural connections. Fratalocchi notes that the nanolasers would appear invisible to an observer until perturbed by a nearby object. Consequently, arranging the cylindrical light sources into a loop could be used to produce a chain reaction of light emissions, tunable down to as small as femtosecond pulse times. “It’s really like a population of fireflies, where the individuals synchronize their emissions into beautiful patterns,” he explains “When we place the nanolasers close together, we can get similar control over the pulses.” The team’s models suggest that integrating different loops of anapole nanolasers may produce oscillating, dynamic patterns useful for reproducing brainlike activities, such as machine learning and memory retrieval at low cost because the platform needs only inexpensive silicon wafers to work. Gongora, J. S. T., Miroshnichenko, A. E., Kivshar, Y. S. & Fratalocchi, A. Anapole nanolasers for mode-locking and ultrafast pulse generation. Nature Communications 8, 15535 (2017).
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Aamir Farooq stands with the twin-opposed piston rapid-compression machine at KAUST.
IGNITING FUTURE FUEL RESEARCH P S E A collaboration between KAUST and Saudi Aramco scientists to test future fuels could bring a new era of highly efficient gasoline engines. Gasoline compression ignition (GCI) is an experimental engine technology that could consume 25% less energy than a conventional automobile engine, suggests well-to-wheel lifecycle analysis. GCI uses a gasoline-type fuel, but rather than ignited with a spark, it is compressionignited like diesel. GCI could therefore be a best-of-both-worlds engine technology: combining the fuel efficiency of diesel engines with the low NOx and soot-particle emissions of gasoline. To optimally design a GCI engine, engineers need detailed knowledge of the low-octane gasoline fuel they would run on. Aamir Farooq at KAUST’s Clean Combustion Research Center, and his collaborators, have analyzed the combustion chemistry of two low-octane
26
gasolines ignited under engine-relevant conditions. “Our focus was to probe the chemical kinetics of auto-ignition of two low-octane gasolines with widely different compositions but similar octane ratings,” says Tamour Javed, who worked on the project as part of his PhD research. “To optimize the performance of GCI engines, we used high-fidelity predictive computer simulations,” explains Farooq. “A big part of such simulations is the description of fuel chemistry.” But a real gasoline fuel is much too complex a chemical mixture to simulate. “Instead, we try to formulate a simpler representation of the real fuel, known as a surrogate.” The team compared each low-octane gasoline with a potential two-component surrogate, measuring how closely its ignition behavior mimicked the real fuel. In most conditions, the two-component surrogate proved to be a good representative of real low-octane fuel, its behavior only diverging at low ignition temperatures. “For higher accuracy at
low temperatures, we proposed a multicomponent surrogate,” Farooq says. Although it will take a significant update in refinery infrastructure to bring low-octane fuels to market, in the short-term, low-octane fuels could be made by combining conventional fuels, Farooq adds. “Studies to test the feasibility of mixing diesel and gasoline fuels to match the characteristics of a low-octane gasoline are underway in our laboratory.” For Javed, meanwhile, there was also a personal benefit to the project; he recently took up a job with project partner Saudi Aramco after completing his studies “The project not only paved the way for my employment, but also it was a nice learning experience for a young researcher to interact with industry,” he says.
KAUST
Simple two-component mixtures are good surrogates for studying the ignition properties of next-generation gasolines.
Javed, T., Ahmed, A., Lovisotto, L., Issayev, G., Badra, J. Sarathy, M.S. & Farooq, A. Ignition studies of two low-octane gasolines. Combustion and Flame 185, 152–159 (2017).
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Mangroves provide food and shelter for wetland animals, but because they also protect against erosion and extreme weather, they build resiliency against climate change. Mangroves offer an important natural source of CO2 storage. With over 150 hectares of mangroves along the shores of KAUST, we aim to conserve this precious resource for the nation as the Red Sea’s most intense carbon sink.
GUARDING THE ENVIRONMENT Learn more DISCOVERY.KAUST.EDU.SA
Using low-cost absorption desalination methods, MEDAD Technologies combines multi-effect distillation technology with thermally driven processes called adsorption desalination to produce distilled water. MEDAD is one example of our start-ups that thrive in the strong culture of innovation supported by our Innovation and Economic Development initiatives.
PRODUCING SUSTAINABLE FRESH WATER Learn more DISCOVERY.KAUST.EDU.SA
O T N I G N I V DEL RED SEA TH E E T S OF T H
F WAT ER
TANE SINCLAIR-TAYLOR
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T HE SECR NR AV EL L ING
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THE WARMEST BODY OF WATER
With an area of nearly 440,000km2 square, the Red Sea has the warmest deep-sea waters of any sea or ocean, reaching 21°C at a depth of 2,800m. The Red Sea has a unique evolutionary history, partly due to its isolation from the Indian Ocean. As a result, as much as 50% of the species in the Red Sea live there exclusively. It harbors dozens of drowned hypersaline lakes that represent extreme microbial ecosystems, offering a wealth of research opportunities for scientists. Because of its unique properties, it is often regarded as a natural experiment with results that illustrate the effects of climate change on oceans.
MANGROVES
Mangrove reforestation projects in the Red Sea are working: total vegetation coverage has increased from 120km2 in 1972 to 135km2 in 2013 despite losses from development, logging and grazing.
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R e d a S e
The root zone of the grey mangrove, Avicenia marina, has at least 15 species of microbes that may have potential uses as medicines or for pollution cleanup.
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THRIVING IN THE VENT
The Red Sea has at least 25 hydrothermal vents that are teaming with relatively unstudied microbes. These microbes have modified their genetics to thrive in water that is extremely salty and hot.
HELPING EACH OTHER OUT
The symbiotic relationship between microbes and their coral hosts may help protect corals from warm and salty stresses.
HIGH SALINITY
The Red Sea is one of the only major bodies of water with no permanent river flow into it.
DEEP SEA MICROBES
Some types of microbes living in hydrothermal vents may have uses in alternative energy: they could simultaneously clean wastewater and generate electricity.
WHAT IS UNIQUE ABOUT THE RED SEA?
The Red Sea is full of resources for the Kingdom of Saudi Arabia, but it is fragile: extreme care must be taken when collecting its resources.
Susana Agusti
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Many of the species found in the Red Sea cannot be found anywhere else. Combined with the unique conditions in the Red Sea, these endemic organisms give us a glimpse into how other organisms might adapt to changing climate conditions.
Michael Berumen
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EXTREME EVENTS
MANAGING CORAL REEFS
ADAPTING TO WARMER TEMPS
Coral reefs in Sudan have 62% more biomass than similar reefs in Saudi Arabia: careful reef management in KSA would benefit reef ecosystems.
Coral reef fish can acclimate to warmer temperatures in just two generations.
DIET DRIVES GUT BACTERIA
The diet of reef fish determines what type of microbes live in its gut, which in turn affects its development, immunity and behavior.
ADAPTING TO POPULATION CHANGE
Clownfish “families” normally comprise one mature male and female plus numerous juveniles. If the female disappears, the remaining male alters hormone levels to transform into a female, restoring the previous gender balance.
MAPPING THE FIRST GENOME
The first sequenced genome of a coral reef fish revealed nearly 30,000 protein-coding genes: mapping the genome helps to manage coral reefs and understand fish evolution.
BACTERIA MAKE ALGAE EASIER TO STOMACH
Giant bacteria in the gut of coral reef fish help them to digest different types of algae but may also help develop new products, such as biofuels.
Our young ocean displays extreme conditions that places it in the global focus to understand how vulnerable marine life may cope with current climate change.
Carlos Duarte
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A small inlet that features the complex circulations of a global ocean. These sustain a unique reef system along its shores and are best studied using all available information from observations and physical models. Because of the lack of historical data in its basin, the models are crucial for understanding its past and projecting its future climate.
Ibrahim Hoteit
CREDITS: DESIGN: AMR RAHMA, SEA VIEW: RASICA/ SHUTTERSTOCK, SHORE LINE: NANOSTOCKPHOTO/ ISTOCK / GETTY IMAGES PLUS, CORAL REEFS: ANNA ROIK, FISH ILLUSTRATIONS: COURTESY OF THE INTEGRATION AND APPLICATION NETWORK, UNIVERSITY OF MARYLAND CENTER FOR ENVIRONMENTAL SCIENCE, MAP: PETER HERMES FURIAN/ SHUTTERSTOCK, MANGROVE ILLUSTRATION: ROBERTDEWIT/ ©TURBOSQUID 2017
Violent storms carry dust across the Red Sea from Africa to Saudi Arabia, bringing nutrients to boost fisheries and agriculture; however, they also blow over particulates that hamper solar-energy devices.
Our new research identifies the entire northern Red Sea region, covering a 1,500km of coastline, as a refugia for coral reefs of global significance. We need to do everything we can to stop any other stressors and to protect the corals in this area.
Christian Voolstra
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EXPLORING THE RED SEA
MANY OUTLOOKS ON THE RED SEA’S FUTURE Located on the banks of the Red Sea, KAUST is especially well-positioned to explore this historically understudied body of water. Researchers at the university bring different disciplines and backgrounds to conduct research that is adding to our understanding of the unique sea. The Red Sea is normally warmer than other seas and oceans around the world, but researchers from KAUST observe that it is warming faster than the global average due to climate change. This could challenge the ability of the Red Sea’s organisms to adapt fast enough to survive. The analyses, conducted by a multidisciplinary team spanning all three divisions at KAUST, provide vital data that could help predict the future of the Red Sea’s marine biodiversity when supplemented by evidence to be gathered on the thermal limits of local organisms. Analyses of satellite sensing data from 1982 to 2015 show that the Red Sea’s maximum surface temperatures have increased at a rate of 0.17 ± 0.07°C per decade, exceeding the global ocean-warming rate of 0.11°C per decade. Maximum sea-surface temperatures were found to increase from north to south along the Red Sea basin, with the coolest temperatures located in the gulfs of Suez and Aqaba in the far North. These two gulfs, however, are showing the highest rates of change compared to the rest of the basin at four times the global average ocean-warming rate. Maximum surface temperatures are also recorded to be advancing by about a quarter of a day per decade. Systematic monitoring efforts are needed to assess the
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impacts of these rapid warming rates on coral bleaching and mass marine organism mortality events, says KAUST PhD student of marine science, Veronica Chaidez. Currently, no such monitoring exists in the Red Sea, but Chaidez is testing the thermal capacities of some of the basin’s plants and animals in the laboratory. A model that incorporates data on temperatures, organism thermal limits, and other relevant biological data could help predict impacts of warming on the local ecosystem. Another team, led by Associate Professor of earth science and engineering Ibrahim Hoteit, set out to discover how the El Niño Southern Oscillation (ENSO) affects rainfall in the Red Sea Convergence Zone (RSCZ), an area characterized by cloudy skies and drizzle that contrasts with the typically clear weather of the region. “The Red Sea is a narrow basin; thus, it requires high spatially resolved data to accurately describe variations in the RSCZ,” explains Hoteit. “This means we require extensive and accurate datasets to assess the influence of the ENSO variability on the region’s rainfall.” The team modeled rainfall patterns between 1979 and 2016. This involved combining data from various datasets. The researchers first identified the position and intensity of
KAUST / TANE SINCLAIR-TAYLOR
The future of the Red Sea will be different to its past as it begins to experience the impacts of a changing climate. A broad approach is needed to understand how the Red Sea can adapt.
The Research Vessel Thuwal enables KAUST’s marine research community to traverse the vast and largely unexplored waters of the Red Sea.
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the RSCZ and the locations of the associated high- and lowpressure systems. Then, to explore the mechanisms responsible for rainfall, they analyzed different variables, such as convective available potential energy, total column perceptible water vapor and evaporation. “Because rainfall intensity is associated with the meeting of different water-vapor fluxes, we used a moisture budget analysis to identify the sources of moisture and to estimate the amount of rainfall in the region,” says Hari Dasari, the first author of the study. They found that the RSCZ shifts northward during the warming El Niño phase of the ENSO, transporting more moisture from the Arabian Sea and increasing the number of rainy days and the intensity of rain events. This results in cooler than normal air from the North combining with warm air from the South over the RSCZ. “We are working on building advanced models for short- and long-term predictions as well as investigating how changes in the global circulation patterns during ENSO years are connected with the Red Sea weather and climate, and vice-versa,” explains Hoteit. While change in rainfall patterns may not be very damaging, the Red Sea basin is home to natural disasters like dust storms, droughts and floods. “These extreme events can affect communities and damage infrastructure,” says Sabrina Vettori, a doctoral student supervised by Marc Genton and Raphaël Huser. Predicting these events is hard—not only are they rare, but also because only few of the millions of entries in datasets relate to extreme events. Increasing the number of observation variables (like temperature and wind speed) dramatically increases the predictive power of a simulation model, but the statistical dexterity needed to correctly pick out and predict
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the combination of conditions leading to extreme events is immense. Multivariate simulations generally follow one of two approaches: The first are parametric approaches that configure the model by using a set of variables to best approximate the behavior described by the data. The second are nonparametric approaches, which are statistical methods that fit a function to data but use no underlying assumptions or constraints. Both approaches have pros and cons, and the best method depends on the application,” says Huser. “Nonparametric methods are typically more flexible than parametric methods, making them less prone to bias, but they are usually limited to small dimensions,” explains Huser. “Parametric methods can be applied to much higher-dimensional problems, such as spatial applications with data recorded at a large number of monitoring sites, but are sensitive to errors in the underlying parameters and assumptions. In their research, the team developed a computational tool to implement nonparametric methods and conducted a vast and systematic simulation to compare nonparametric and parametric estimator performance in up to five dimensions under various scenarios. These methods provided significant insight into higher dimensional settings. “These estimators can be used to better model the location and magnitude of extreme events and to assist in risk assessment and the identification of trends and variability estimates,” says Genton. 1. Chaidez, V. Dreano, D., Agusti, S., Duarte, C.M. & Hoteit, I. Decadal trends in Red Sea maximum surface temperature. Scientific Reports 7, 8144 (2017). 2. Dasari, H. P., Langodan, S., Viswanadhapalli, Y., Vadlamudi, B. R., Papadopoulos, V. P. & Hoteit, I. ENSO influence on the interannual variability of the Red Sea convergence zone and associated rainfall. International Journal of Climatology (2017). 3. Vettori, S., Huser, R. & Genton, M. G. A comparison of dependence function estimators in multivariate extremes. Statistics and Computing (2017).
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EXPLORING THE RED SEA
MICROBIAL COMMUNITIES HAVE A SEASONAL SHAKE-UP B E S E Seasonal changes in turbulence and nutrient availability are shown to shape microbial communities in the Red Sea. “A lot of the marine ecosystem is ultimately based on how microbes live and what they’re doing,” explains research scientist John Pearman, who undertook the study. “Knowing how microbes respond is important to understand how the ecosystem is going to function.” Using a CTD rosette sampler that combined sampling bottles with sensors for water temperature and conductivity, researchers in the Saudi Aramco- KAUST Center for Marine Environmental Observations measured water conditions and collected samples for the analysis of planktonic microbial communities in various parts of the Red Sea in different seasons. Sequencing rRNA genes from these samples gave them snapshots tracking how communities changed over time. Led by marine scientists Susana Carvalho and Burton Jones, the research team found overall that diversity was greatest in the Southern Red Sea and lowest in the central region. However, communities varied across all regions and seasonally in both the North and the South. The Southern Red Sea had the lowest diversity during the fall, when high nutrient availability provided enough energy for larger plankton
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A CTD rosette being lowered into the water to provide profiles of chemical and physical parameters through the water column (e.g., salinity, temperature, depth, oxygen).
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Turbulence and nutrient availability drive changes in Red Sea microbes.
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GIANT BACTERIA MAKE ALGAE EASY TO STOMACH Symbiotic giant bacteria enable Red Sea surgeonfish to specialize their diets.
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At specific depths, bottles of the CTD rosette are closed and water is collected for analysis.
to grow, while low levels of turbulence minimized interactions with predators. As a result, these groups were able to dominate communities, diluting their richness. In the spring, higher turbulence levels made it easier for predatory zooplankton to find their prey and keep them in check, increasing the communities’ diversity. In the Northern Red Sea, nutrient levels remain lower throughout the year, but seasonal changes in turbulence altered the composition and structure of microbial communities, although the changes were smaller than in the South. These findings support a 15-year-old model linking community structure with physical factors, such as turbulence and nutrient levels. “The original study was based on phytoplankton communities, but we were able to target the whole microbial community through sequencing and show that the original theory is applicable to the whole planktonic community,” says Pearman. Despite the new support, the model remains a work in progress, with researchers
incorporating the effects of additional factors, such as currents, as new data become available. “A lot is still unknown about the marine microbial environment, though they’re actually the basis of food webs, chemical cycling and carbon fixation,” says Pearman. “It ’s extremely important to know how the microbial community responds to differences in temperature, nutrients and turbulence especially in light of climate change or the anthropogenic nutrient enrichment due to the development of coastal regions.” The team plans to continue refining their understanding by studying microbial communities along the latitudinal axis of the Red Sea, further from coastal influences, as well as incorporating the effect of circulation in their models. Pearman, J.K., Ellis, J., Irigoien, X., Sarma, Y.V.B., Jones, B.H. & Carvalho, S. Microbial planktonic communities in the Red Sea: high levels of spatial and temporal variability shaped by nutrient availability and turbulence. Scientific Reports 7, 6611 (2017).
Red Sea surgeonfish use metabolically diverse giant bacteria to digest different types of algae, according to new research. Not only do these findings explain the basis of surgeonfish diversity, but they may also provide a valuable genetic resource for biofuel research. An international team led by KAUST researchers used high-throughput sequencing techniques to study symbiotic microbe communities in the intestines of marine-algae-feeding Red Sea surgeonfish. By analyzing the genomes, they discovered that the communities are dominated by a single group of giant bacteria known as Epulopiscium, and that they lack the diversity found in the microbiomes of terrestrial herbivores. “The degradation of plant biomass in terrestrial vertebrates usually requires cocktails of enzymes originating from gut microorganisms, each of which has the capacity to break down different constituents,” explains KAUST research scientist David Ngugi, who led the study. Algae lack many of the complex cell wall constituents and polysaccharides found in land plants, such as lignin and cellulose, and so a simpler microbial community is likely sufficient to digest them. Nevertheless, analyzing gene expression revealed major differences between the Epulopiscium in surgeonfish specialized by feeding on red or brown algae. “Depending on the algae that the host is feeding on, the Epulopiscium have corresponding enzymes to break down those polysaccharides,” says Ngugi. “So much so that you probably cannot take an Epulopiscium from a red-algae eating host and transplant it to brown-algae eating host because they don’t have the metabolic capacity to Acanthurus sohal are reported to feed on either turfing or filamentous red and green algae.
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EXPLORING THE RED SEA
Epulopiscium bacteria are helping to explain the diversity of surgeonfish and the specialization of their diet.
“The kind of symbiosis that has developed in order to utilize the specific food resources in the reef has occurred over evolutionary time scales.” The ability to ferment algae will make Epulopiscium a valuable genetic resource for the development of algal-based biofuels. The findings also highlight the link between food, fish and microbes underpinning the diversity of reef communities. “The kind of symbiosis that has developed in order to utilize the specific food resources in the reef has occurred over evolutionary time scales,” says Ngugi. “Our data suggest that it’s not something that can be acquired or re-established in a short time.” Ngugi, D.K., Miyake, S., Cahill, M., Vinu, M., Hackmann, T., Blom, J., Tietbohl, M., Berumen, M.L. & Stingl, U. Genomic diversification of giant enteric symbionts reflects host dietary lifestyles. Proceedings of the National Academy of Sciences 114, E7592–E7601 (2017).
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degrade what the other host is eating.” This specialization helps explain the diversity of reef surgeonfish. The researchers suggest dividing the symbiotic Epulopiscium into three genera. The team also tracked gene expression in Epulopiscium throughout a day and found that it matched the host’s lifestyle, with genes related to digestion active during the morning when the host was feeding. “That was really exciting,” says Ngugi, because it clearly demonstrated the giant bacteria’s role in the gut.
CAN CORAL REEFS CHANGE WITH THE TIMES?
Coral ecosystems may be able to adapt rapidly to climate change through natural plastic responses. B E S E
Reef-building corals and the ecosystems that they support are under threat as climate change rapidly alters the environments they have adapted to live in. Corals may have methods to adapt more rapidly than scientists previously thought, but the extent and exact range of mechanisms is not yet fully understood. KAUST marine scientists Manual Aranda, Timothy Ravasi, Michael Berumen and Christian Voolstra— along with an international team of experts—are exploring a diverse suite of mechanisms that might help corals adapt and survive in the coming decades, and they provide a comprehensive set of guidelines for new research.
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“Now, these rapid adaptation mechanisms are vital because creatures might not have enough time to adapt through Darwinian genetic evolution,” says Aranda. “Our main goal, therefore, is to find out what other molecular mechanisms marine organisms can use to respond quickly and effectively to environmental pressures.” The ability to respond rapidly to changing environments is called plasticity. Many plants and animals are known to change their physical characteristics, known as a phenotype, and even pass this information from one generation to another without altering their actual genes. An example of plasticity in humans, notes Aranda, would be the changes that occur from exercise as our muscles respond, changing our strength, fitness and tolerance levels to fit specific environments and conditions. “Transgenerational plasticity, or TGP, is if animals can alter their epigenome—through modifying proteins, or switching allegiance to a different bacterial symbiont, for example—and leave a signal for their offspring to pick up and use if necessary,” says Ravasi, who uses genomic approaches to study reef fish responses to increasing ocean temperature and acidification. “Together with the international research community, we hope to ensure meaningful research is conducted to establish whether corals and their associates can use
From left to right: Michael Berumen, Christian Voolstra, Manuel Aranda, Timothy Ravasi.
TGP. It is not easy to verify whether a particular trait is being passed down generations because of TGP, so studies must be carefully designed.” Aranda, who studies adaptive responses and epigenetics of corals, explains that experiments must use multiple generations of a model organism to verify TGP. Because reef-building corals can live for decades and take a long time to reproduce, Aranda works with other related animals, such as anemones and jellyfish. “You place an adult into a changed environment, for example warmer water, and watch to see if it adjusts in some way. Its offspring might pick up the same trait purely because they are conceived and born in warmer conditions. So to ensure TGP is definite, you bring up the children in normal water conditions instead. You then take their offspring—the grandchildren of the original creature—and place them into warmer conditions again. If they display an immediate ability to cope with the conditions, then this points to TGP.” Another way that corals might be able to adapt rapidly is by changing their microbiome—the bacterial and algal symbionts living within coral tissues in a mutually beneficial relationship. Coral expert Voolstra is convinced that the bacteria associated with the coral animals could hold a key to future coral reef health. “Bacterial symbioses are present in all living things and yet, until recently, it has been overlooked and underresearched,” he says. “We recently demonstrated that different bacteria associate with corals in warmer waters, suggesting that they might help to increase the heat tolerance of corals, for example.” Voolstra’s team is now analyzing different microbes, one at a time, to determine how each one contributes toward coral health. “We have been investigating heritable components too, crossing mothers and fathers from different environments and tracing their microbial associations; this very new data appears to show that some degree of inheritance exists,” adds Voolstra. If reef-building corals can pass on valuable information to their offspring through TGP, then the future of coral reefs may not be quite as bleak as scientists feared. However, as Berumen points out, researchers should also maintain a wide ecological perspective on this rapidly changing situation. “We must continue to incorporate wider studies of reefs as whole ecosystems while investigating the intricacies of epigenomics. Our ideas are a starting point from which novel, refined and hopefully more standardized research projects will emerge. These will contribute to a wider understanding of our coral reefs and may inform future management of marine ecosystems as the full impact of climate change becomes clear.” Torda, G., Donelson, J. M., Aranda, M., Barshis, D. J., Bay, L., Berumen, M. L. et al. Rapid adaptive responses to climate change in corals. Nature Climate Change 7, 627-636 (2017).
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When faced with high salinity, the tiny plant cells within coral tissue alter their metabolites to better cope with stress.
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Tiny plant cells, known as dinoflagellates, that live within coral tissue can help to regulate the osmotic pressure in corals to better cope with a highly saline environment. KAUST researchers suggest this may be one of the secrets of corals from the Red Sea and Persian/Arabian Gulf, which are extremely tolerant of heat in extraordinarily salty waters. Coral reefs have high biodiversity and economic value, yet these vital ecosystems are at risk as rising sea temperatures increase the frequency of local and global coral bleaching events. KAUST researchers are searching for strategies to help reduce future reef loss. “The effects of temperature and pH changes are intensely studied; however, the implications of climate-related salinity changes on corals have received little attention,” explains PhD student Till Röthig, who led the paper with postdoctoral fellow Michael Ochsenkühn.
TILL ROETHING
HELPING CORALS TO COPE WITH PRESSURE
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The foundation of coral reefs is based on a symbiotic relationship of the coral animal with dinoflagellate Symbiodinium species, which provide energy to the coral in exchange for nutrients and carbon dioxide. The researchers found that free-living Symbiodinium cope with highly saline conditions by producing and accumulating compatible organic osmolytes (COOs) to adjust their osmotic pressure. Screening Symbiodinium cultures exposed to low, ambient and high levels of salinity revealed that the carbohydrate floridoside is universally present at high levels in algae and corals at high salinities. “The synthesis of COOs represents a quickly available and viable long-term solution to establish an osmotic equilibrium,” explains Röthig. “Our research demonstrates that the COO floridoside is used as a conserved osmolyte to help Symbiodinium and corals to osmoadapt to the saline conditions.” Also important is that floridoside can help counter reactive oxygen species (ROS) produced through salinity stress, adds team leader, Christian Voolstra. “ROS are produced under salinity stress, but are
Bleached corals from Farasan Banks in the Red Sea. Coral bleaching—a visible footprint of climate change— occurs when stressed corals lose their dinoflagellate symbionts. What remains is the translucent polyp tissue showing the white coral skeleton. Bleaching is followed by the death of the corals and loss of fish populations and other reef species.
also produced under heat stress where they can cause coral bleaching,” explains Voolstra. “Thus, the same molecule that adjusts the osmotic equilibrium and protects the dinoflagellate and coral from stress from high salinity may inadvertently contribute to increased heat tolerance due to its ROS scavenging properties.” Knowing how salinity changes impact corals has important implications for management especially considering the effects of climate change,” says Röthig. “For example, suggested transplantation of temperature-resilient corals from the Red Sea to other habitats may not confer the desired temperature resistance in a new, less saline environment. Conversely, increases in seawater salinities in some places may help corals to become more stress tolerant.” Ochsenkühn, M.A., Röthig, T., D’Angelo, C., Wiedenmann, J. & Voolstra, C. The role of floridoside in osmoadaptation of coral algal AQ1 endosymbionts to high-salinity conditions. Science Advances 3, e1602047 (2017).
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HERBAL MEDICINE SHOWS POTENTIAL TO TREAT CANCER Herbal remedy plants native to Saudi Arabia are shown to have potential as treatments for cancer.
Researchers from KAUST have been searching locally for plants that have potential for use to combat cancer. They have identified that three plants used for traditional medicine in Saudi Arabia are worthy of further investigation for anticancer properties. Cancer is a leading cause of illness and death worldwide. In 2015, the World Health Organization (WHO) recorded 8.8 million cancer-related deaths, but almost twice as many cases are diagnosed each year. And the WHO predict that the number of cancer diagnoses is likely to continue to increase by about 70% for at least the next two decades due to growing longevity. Seeking to expand the armory of cancer treatments—especially ones that are simple and inexpensive to manufacture—a team led by Timothy Ravasi and Christian Voolstra from KAUST has investigated the biological potential (bioactivity) of a range of plants used locally in traditional medicine. Use of herbal medicines is common in Saudi Arabia, explains Ravasi’s PhD student, Dina Hajjar. “However, there are almost no scientific studies. Saudi people tend to use information inherited from their families to decide about these plants without validated knowledge of their biological or chemical activity.”
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The effect of plant fractions of HeLa cells. Top: Nuclei, mitochondria, cytochrome C and NF-κB. Bottom: Nuclearactin-tubulin organelles.
The team initially investigated 52 plants before they homed in on three plants that showed promise—Juniperus phoenicea (known in herbal medicine as Arar or Phoenican juniper), Anastatica hierochuntica (known as Kaff Maryam or the Jericho rose) and Citrullus colocynthis (known as Hanzal or bitter cucumber)1.
The team used cell-based phenotypic profiling via imaging-based high-content screening to assess anticancer activity. This approach followed a technique developed in 2016 by Stephan Kremb and Christian Voolstra2 that uses a comprehensive marker panel with standardized settings—an efficient process that could potentially be easily adopted by other laboratories. This meant the team compared the cytological profiles of fractions taken from the plants with a set of reference compounds with established mechanisms of action. This enabled the team to show that these three plants contain potent anticancer substances—topoisomerase inhibitors, compounds that can block the topoisomerase enzymes that control changes in DNA—that could be used to develop novel anticancer inhibitors. There are many steps, however, before these compounds are properly tested and available for clinical
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A DVA N C I N G H U M A N H E A LT H
PhD student Dina Hajjar has been examining anticancer properties of plants used in traditional medicine in Saudi Arabia.
NANOPARTICLES TAKE A BITE OUT OF INFECTIONS Spiky-shaped additives help antimicrobial coatings sense and inhibit bacteria growth on dental devices.
treatments for cancer. “The active compounds identified in the study will need to be evaluated and better characterized,” says Hajjar. “Also, active compounds need to be synthesized and tested in vivo.” This study proves the power of using imaging-based high-content screening in revealing information about the bioactivity of unknown natural resources. Hajjar adds that it also highlights the opportunity for more exciting discoveries amongst the natural resources of Saudi Arabia. 1. Hajjar, D., Kremb, S., Sioud, S., Emwas, A. H., Voolstra, C. R., & Ravasi, T. Anti-cancer agents in Saudi Arabian herbals revealed by automated high-content imaging. PLOS ONE 12, e0177316 (2017). 2. Kremb, S. & Voolstra, C. R. Highresolution phenotypic profiling of natural products-induced effects on the single-cell level. Scientific Reports 7, 44472 (2017).
Antibiotic-resistant bacteria that colonize surfaces and medical equipment are causing alarming annual rises in the number of patients becoming infected in hospitals and clinics. A KAUST team is working to reduce these numbers with a smart polymer that changes color and activates natural antimicrobial enzymes when bacterial contamination is detected. Constant exposure to salivary bacteria makes dental tools, such as reusable X-ray imaging plates, ideal environments for virulent biofilms. One solution to this problem is to coat devices with polymers embedded with nanoscale crystals that slowly release silver ions, a broadspectrum biocide agent. However, challenges with nanoparticle leaching, have thwarted advancement of this technology. Associate Professor Niveen Khashab, her PhD student Shahad Alsaiari and colleagues from the University’s Advanced Membranes and Porous Materials
Center realized that switching to gold nanoparticles could give antimicrobial coatings detection capabilities—these tiny crystals have sensitive optical properties that can be tuned to spot specific biomolecular interactions. But incorporating them safely into polymers required new types of nanofillers. “Nanofillers are small chemical agents distributed in the matrix of a polymer composite,” explained Khashab. “They’re dopants, so they improve on the regular material and introduce new properties—in our case, making the coating antibacterial.” The team’s approach uses gold nanoclusters treated with lysozyme enzymes that have innate defenses against pathogens, such as Escherichia coli, commonly known as E. coli. They attached these colloids to the surface of slightly larger, porous silica nanoparticles stuffed with antibiotic drug molecules. Normally, this gold-silica complex emits glowing, red fluorescent light. But when the lysozyme units encounter bacteria, TETRA IMAGES / GETTY IMAGES
SOU MIYAKE / TILL ROTHIG AND ANNA ROIK / KAUST
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A rapid test under UV light reveals if dental imaging plates are contaminated with bacteria, thanks to the use of polymers embedded with multi-functional nanoparticles.
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a strong attraction for cell walls rips the gold nanoclusters from their silica partners—an action that simultaneously switches off fluorescence and releases the antibiotic cargo.
“Nanofillers are small chemical agents distributed in the matrix of a polymer composite” Blending experiments revealed the gold-based nanofillers integrated thoroughly into polymer composites and exhibited minimal leaching during trials with E. coli. Khashab attributes these favorable polymer interactions to the sharp exposed edges of gold clusters on the silica spheres The researchers tested their concept by comparing X-ray dental plates with and without the smart polymer coating. Both samples yielded the same high-resolution images of teeth and bone structure. However, only the coated plate enabled rapid visual assessment of bacterial contamination, simply by illuminating the device with a UV-lamp and looking for color change. Successful release of the antibacterial agent also drastically decreased biofilm buildup. “The process of coating is easy,” notes Khashab. “We are looking at improving this technology to include other medical devices of different sizes and shapes.” Alsaiari, S.K., Hammami, M.A., Croissant, J.G., Omar, H.W., Neelakanda, P. ... & Khashab, N.M. Colloidal gold nanoclusters spiked silica fillers in mixed matrix coatings: Simultaneous detection and inhibition of healthcare-associated infections. Advanced Healthcare Materials 5, 1617–1626 (2016).
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THE HIDDEN ORDER IN DNA DIFFUSION The movement of DNA molecules seemingly explained by random motion conceals a more orderly march.
B E S E A different approach to analyzing the motion of diffusing molecules has helped overturn the long-held assumption that DNA molecules move in a haphazard way. KAUST researchers reveal for the first time that DNA molecules move not by random Brownian motion but by a nonrandom walk related to polymer dynamics in a way that conserves overall Brownian characteristics. “Brownian motion is a process whereby molecules move randomly in a fluid by colliding with other molecules,” explains Maged Serag, a postdoctoral researcher at KAUST. “In living cells, Brownian motion allows molecules to move rapidly and efficiently between cell organelles and interact with other molecules.” For many decades, scientists have used a relatively simple test to determine whether molecular diffusion is Brownian: when the mean-square displacement (MSD) of a population of molecules increases
A new single-molecule tracking method based on fluorescence molecular imaging revealed nonrandom motion of DNA molecules.
linearly over time. In a uniform medium like pure water, this means that a drop of saline solution will expand at a rate that makes the MSD increase linearly with time. DNA conforms to this macroscale diffusion behavior, and so it has been assumed that its motion is Brownian like other molecules. However, it is also known that DNA, being a long polymer molecule, writhes spontaneously due to intramolecular forces. “The DNA molecule can be viewed as a semiflexible chain,” said Serag. “If we follow its motion at short timescales and in a space close to its size, we see worm-like motional behavior.” Serag’s advisor at KAUST, Satoshi Habuchi, set out to see whether this writhing motion could affect the diffusion of DNA. “Dr. Serag came up with a unique idea to describe the motion of a molecule based on the probability of occupying lattice sites rather than by mean-square displacement,” says Habuchi. “MSD has been the standard method to detect deviation from Brownian motion, but it does not reveal any nonrandom motion for DNA molecules. By using this probabilistic approach instead, we were able to detect and quantify hidden nonrandom motion.” By developing a new theoretical framework in which motion is modeled in a step-wise manner accounting for molecular flexing, DNA molecules were found to move nonrandomly with varied speed and molecular track in a way that precisely conserved the Brownian linear MSD. “The most important result of this study is that we have demonstrated that a linear MSD does not always indicate underlying Brownian motion,” explains Habuchi. “With this new theoretical framework, we can detect the nonrandom motion of single molecules that cannot be captured by conventional MSD analysis.” Serag, M. & Habuchi, S. Conserved linear dynamics of singlemolecule Brownian motion. Nature Communications 8,15675 (2017).
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A DVA N C I N G H U M A N H E A LT H
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SHAPING UP AGAINST PATHOGENS Plants can reprogram their genetic material to mount a defensive response against pathogens, which may have applications for agriculture.
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CHRIS SMART, NYSAES, GENEVA NY
B E S E A missing link in the complex molecular pathway by which plants resist pathogens has been identified by an international team headed by Heribert Hirt. This finding highlights a potential mechanism that could be harnessed to “vaccinate” crops against disease. Plant defense is controlled by genes, made of DNA, which encode proteins. DNA is packaged into an aggregate called chromatin, the shape of which affects whether genes are available for protein building. Changes to the chromatin structure are epigenetic—potentially heritable without altering the DNA sequence itself—and have been associated with pathogen attack. Pathogens produce small molecules called microbial-associated molecular patterns (MAMPs), which plants recognize via a bipartite receptor protein: part one senses MAMPs outside the plant cell and stimulates the second part inside the cell to act. The latter is a kinase, an enzyme that transfers phosphate groups onto target molecules (phosphorylation), and its action is the first in a sequence of MAMPtriggered phosphorylations between mitogen-activated protein kinases (MAPKs). Hirt, who is now a professor of plant science at KAUST, discovered these in 1997. The link between MAPKs and epigenetic chromatin modification has remained elusive until this new finding by Hirt’s team, who included Assistant Professor Moussa Benhamed, serveral postdocs and a master’s student from the University’s Desert Agriculture Initiative. Using the model species
Damage caused on tomato plants upon infection with Pseudomonas syringe bacteria.
Heribert Hirt is looking deep into the genes of plants to find ways to build up new useful traits in crops.
Arabidopsis thaliana, the researchers activated the MAPKs using a bacterial MAMP. Then, in a series of experiments dubbed “the phosphoproteomics pipeline,” they searched for phosphorylation events. Enticingly, they found that the final MAPK in the chain, MPK3, phosphorylates an enzyme, histone deacetylase (HD2B), which regulates DNA compaction into chromatin. The team showed that, in mutant Arabidopsis lacking MPK3 or HD2B, many genes, including defense genes, increased in activity. This suggests that, normally, HD2B represses gene activity. Under pathogen attack, MPK3’s action on HD2B reverses this repression. Using fluorescent-tagged HD2B, the team showed that MPK3 phosphorylation makes HD2B move from one cellular location to another, binding a different chromatin region. This pathway releases one set of genes and blocks a second set, fundamentally changing the cell’s molecular makeup. This epigenetic reprogramming is fast and reversible, enabling plants to respond rapidly to changing conditions and to retain a molecular memory facilitating a speedier response to future pathogens. According to Hirt, “epigenetic mechanisms are the mechanism of choice…the phenomenon occurs across all plants in response to all types of MAMPs and pathogens.”
“We are entering a new era investigating the role of epigenetics in plantstress memory.” Hirt believes kinase-triggered chromatin reprogramming is a widespread mechanism, and he is enthusiastic about possibilities for artificially stimulating this process. “Once we better understand the mechanism of inducing pathogen memory, we might be able to induce long-term resistance, similar to human vaccination,” he suggests. “We are entering a new era investigating the role of epigenetics in plant-stress memory.” Latrasse, D., Jégu, T., Huchen, L., de Zelicourt, A., Raynaud, C. ... & Hirt, H. MAPK-triggered chromatin reprogramming by histone deacetylase in plant innate immunity. Genome Biology 18, 131 (2017).
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A BETTER WAY TO REMOVE WATER FROM GAS A breakthrough in generating waterstable metal-organic frameworks allows efficient removal of water from gases.
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P S E The conventional view that metal-organic frameworks (MOFs) cannot be stable in water has been overturned by the development of an MOF that can selectively and effectively adsorb water to dry gas streams. “ The achievement of energy-efficient dehydration by our MOF is revolutionary,” says Mohamed Eddaoudi, Director of the Advanced Membranes and Porous Materials Center at KAUST. Gases, such as natural gas, must be dehydrated before transportation and are used to avoid problems, including pipeline corrosion and blockages due to methane ice formation. Conventional drying agents require an energyintensive regeneration cycle. The new fluorinated MOF developed by the KAUST team achieves the drying and regeneration cycle at relatively low temperatures and requires about half the energy input of conventional procedures. This dramatic
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Left to right: Youssef Belmabkhout, Prashant Batt, Professor Mohamed Eddaoudi and Aleksander Shkurenko.
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Humid Gas
Dry Gas Mild Regenration
A SIMPLE NOSE FOR NOXIOUS GAS Tunable porous MOF materials interface with electrodes to sound the alarm at the first sniff of hydrogen sulfide.
Dehydration
Energy-efficient gas drying achieved by a metal-organic framework.
reduction in energy use highlights the obvious potential for upscaling the innovation to bring huge efficiency savings in the gas production and the transport industries. MOFs are hybrid organicinorganic materials that contain metal ions or clusters held in place by organic molecules known as linkers. Varying the metal components and organic linkers allows researchers to fine tune the structure and chemical properties of MOFs. A major aim of this fine tuning is to create MOFs with cavities that will selectively bind to and retain specific molecules, such as the water that must be removed from a gas stream. “Initially, our aim was to adapt our recently introduced fluorine-containing MOFs to include a periodic array of open metal sites and fluorine centers in the contracted pore system to achieve various key separations,” says Eddaoudi. This exploration led to the discovery of a water-stable MOF, now labeled KAUST8, with unique water adsorption properties and outstanding recyclable dehydration capabilities. Significantly, KAUST-8 removes carbon dioxide along with water, which is a common requirement in industrial gas processing. “I have no doubt that this discovery will inspire scientists in academia and
industry to explore MOFs to address other challenges,” says Eddaoudi. The KAUST team sees additional possibilities, including the removal of water from liquids, such as inks and solvents, used in the electronics industry.
“This discovery will inspire scientists in academia and industry to explore MOFs to address other challenges” Eddaoudi emphasized that the work demonstrates both the power of MOF chemistry and the continuous advancement of the research group he leads at KAUST. This advance is the latest innovation from Eddaoudi’s 20-year exploration of the chemistry of MOFs. Cadiau, A., Belmabkhout, Y., Adil, K., Bhatt, P. M., Pillai, R. S. Shkurenko, A., MartineauCorcos,C., Maurin, G. & Eddaoudi, M. Hydrolytically stable fluorinated metalorganic frameworks for energy-efficient dehydration. Science 356, 731–735 (2017).
P S E A thin-film chemical sensor coated onto an electrode offers a simple, practical way to detect minute traces of toxic gas. Sensors that use metal-organic frameworks (MOFs) can be highly selective for a particular gas because of the porous nature of these crystalline materials and their nanoscale cavities. Recently, KAUST researchers developed a MOF-based sensor that can selectively sense hydrogen sulfide at concentrations of just a few parts per billion (ppb). Their method of altering the structure of the MOF-electrode coating allows them to detect a range of gases. Hydrogen sulfide doesn’t just smell bad; it is harmful to humans at concentrations as low as just a few parts per million (ppm). In industrial settings, where hydrogen sulfide release is a risk factor, gas-sensing systems based on gas chromatography are typically deployed; however, these systems are bulky, complex and expensive. A much simpler sensor has now been developed through collaboration between the KAUST research groups of Khaled Salama, professor of electrical engineering, and Mohamed Eddaoudi, professor of chemical science. By altering the metal and organic components of the MOFs used in Eddaoudi’s sensors, the team fine-tuned the size and shape of the pores and altered the cavities where gases enter. In this way, the material becomes highly selective at adsorbing a particular gas. “Unexpectedly, the sensor was not only able to perform well in the detection of H2S gas in the ppm range but also in the ppb range with a detection limit of about 5.4 ppb,” Eddaoudi says. “This exceptional sensing performance paves the way for the deployment of MOFs as practical sensors for various detection applications of toxic gases and vapors.” Yassine, O., Shekhah, O., Assen, A.H., Belmabkhout, Y., Salama, K.N. & Eddaoudi, M. H2S sensors: fumarate-based fcu-MOF thin film grown on a capacitive interdigitated electrode. Angewandte Chemie International Edition 55, 15879 (2016).
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LOOKING BOTH WAYS FOR NEW-STYLE SEMICONDUCTORS Introducing asymmetry across the two sides of atomically thin materials brings new opportunities in semiconductors. C E M S E Semiconductor materials called dichalcogenides may gain broader properties when asymmetry is introduced across the plane of sheets of bonded atoms. KAUST researchers have created a Janus monolayer that, following Roman mythology, they named for Janus whose two faces looked in opposite directions and was believed to control transitions through gateways. The Janus monolayers may help a transition to novel semiconductor applications in electronics, particularly in nanoelectronics, which relies on manipulating very small groups of atoms. “Our unique method of synthesis paves the way for altering 2D, atomically thin sheets of these materials on an atomic scale,� says LainJong Li, professor of chemical science. Dichalcogenides are made when atoms from the
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YI WAN
transition-metal block in the periodic table combine with those from Group 16—the chalcogens. They have the general formula MX2, where M represents the transition metal and X represents the chalcogens. The KAUST researchers began with the symmetric material MoS2,
Professor LainJong Li (Right) and His PhD students MingHui Chiu (Left) and Chih-Wen Yang (Middle) synthesize Janus twodimensional materials using chemical vapor deposition.
with molybdenum (Mo) as the transition-metal atom and sulfur (S) as the chalcogen. Their achievement was to selectively replace the sulfur atoms on one side of the atomically thin sheets with selenium atoms, creating their asymmetric
Janus monolayer. This is easy enough to describe, but was extremely difficult to perform. “It took us almost three years, step by step,” says Li. It was worth the effort, Li explains because “asymmetry introduces new properties.” In more technical terms, the key useful feature of semiconductor materials is that their electrons can occupy a range of energy levels or spin states. The asymmetry across the plane of a monolayer creates a richer diversity of energy levels, thus opening many more opportunities for use in real-world applications. Li emphasizes that this research is still basic science; his team does not yet have any particular applications for the material “but new physics and phenomena always emerge by discovering new materials,” he says. I n ad d i t i on t o c on ventional semiconductor applications, the researchers believe their asymmetric material could be useful in an emerging field called spintronics. This field uses changes in a property of electrons, known as their spin, rather than just their electric charge as a means of manipulating electronic behavior on atomically small scales. Li now hopes to apply the innovation to other new Janus materials and thus widen the range of opportunities offered by introducing useful asymmetry. Lu, A-Y., Zhu, H., Xiao, J., Chuu, C-P., Han, Y., ... & Li, L. Janus monolayers of transition metal dichalcogenides. Nature Nanotechnology 12, 744-749 (2017).
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KE E PING T H E H E AT OU T Insights into the thermal behavior of metal nitride nanowires could open new avenues in optical electronics.
Most electronic devices currently contain silicon-based chips. Other semiconducting materials show potential, but need further research to become commercially viable. Researchers at KAUST have thoroughly analyzed one such material—metal-nitride nanowires—bringing them a step closer to being useful. When metal-nitride semiconductors are arranged into nano-sized wires they become extra sensitive to light, opening possibilities for
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Metal-nitride nonowires may be used for optical electronics.
optical electronics. One notable challenge however is that although metal-nitride nanowires perform well at low temperatures, thermal effects can greatly affect their performance at room temperature. To address this problem, Nasir Alfaraj with his PhD supervisor Xiaohang Li and coworkers have produced the most detailed study yet of these thermal effects. The researchers prepared gallium-nitride (GaN)based nanowires in a p-i-n structure—a sandwich with layers of so-called p-type and n-type versions of the semiconductor surrounding an unaltered layer. N-type semiconductors are doped with materials that provide extra electrons, while p-types are doped with materials with fewer electrons, leaving “holes” in the crystal structure. Both electrons and holes act as charge carriers, giving semiconductor devices their useful electronic properties. “GaN-based p-i-n nanowires are suitable for fabricating signal attenuators, high-frequency digital switches and high-performance photodetectors,” said Alfaraj. “Yet, their performance
LEFT: GETTY IMAGES, TOP: STOCKBYTE/ GETTY IMAGES, RIGHT: GEORGE DOYLE/ STOCKBYTE/ GETTY IMAGES
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is negatively affected when electrons and holes recombine, especially close to room temperature.” More specifically, when an electric field acts across a nanowire, the balance of electrons and holes can be affected, pumping heat away from the device in the form of thermal radiation. The devices effectively act as mini refrigerators, and their performance declines as they cool. To quantify this effect, Alfaraj and coworkers directed a titanium-sapphire laser onto their nanowires and measured the photoluminescent emissions that came out of the sample. They were then able to
KAUST researchers are opening the way toward a new generation of optical electronic devices that aren’t solely based on silicon.
calculate the photoinduced entropy of the system: a thermodynamic quantity that represents the unavailability of a system’s energy for conversion into work due to luminescence refrigeration. At system temperatures above 250 K, the electron-hole nonradiative recombination processes become dominant—electrons fall into holes, causing a rise in photoinduced entropy and reducing the device performance. “We plan to investigate photoinduced entropy in other materials, such as aluminum-gallium-nitride and zinc-oxide nanowires,” says Alfaraj. “We will also compare different nanowire diameters and investigate other structures, such as thin films.” These studies will assist engineers in making metal-nitride nanowire devices that are thermally stable and suitable for everyday use. Alfaraj, N., Mitra, S., Wu, F., Ajia, I., Bilal, J., Prabaswara, A., Aljefri, R., Sun., Ng, T. Ooi, B., Roqan, I. S. & Li, X. Photoinduced entropy of InGaN/GaN p-i-n double-heterostructure nanowires. Applied Physics Letters 110, 191110 (2017).
“M a k i n g m e t a l - n i t r i d e nanowired devices that are thermally stable and suitable for everyday use”
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NEW ENERGIES IN GAS SENSING An ultrathin semiconducting sheet showing gas-responsive electronic properties may lead to highly sensitive gas sensors. P S E Gas detectors capable of sensing minute quantities of pollutants could help better monitor air quality. KAUST researchers have discovered a two-dimensional electronic material that exhibits high sensitivity to gas molecules,
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such as carbon dioxide (CO 2 ), nitrogen oxides (NOX) and ammonia (NH3). Atomically thin sheets consisting of transition metals associated with chalcogen atoms, such as sulfur, selenium and tellurium, are versatile alternatives to the more conventional silicon-based
semiconductors. Depending on their metal component, these transition-metal dichalcogenide monolayers have band gaps—energy barriers that limit electron flow through a material—that can be tuned to alter their electronic properties. The unique electronic properties of these monolayers have potential to improve a plethora of devices, including fieldeffect transistors, photodetectors and gas sensors. Semiconducting monolayers are proven to be ideal candidates as gas-sensing materials because they have a high surface-to-volume ratio.
For example, MoS2 has been incorporated in field-effect transistors to detect nitrogen monoxide (NO). However, its performance is limited by its relatively low carrier mobility or by the velocity at which its electrons (or holes) move when subjected to an electric field. To overcome these shortcomings, KAUST Professor Udo Schwingenschlögl’s team evaluated the potential of the platinum dichalcogenide PtSe2 for use in gas detectors via sophisticated computational techniques. “Monolayer PtSe2 experimentally shows a high carrier mobility, which can be
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SEMICONDUCTORS WITH AN ALIGNED INTERFACE Atomistic model showing the charge accumulation (yellow) and depletion (red) upon NO adsorption on PtSe2 monolayer. Platinum atoms appear in gray and selenium atoms are shown in green.
Nirpendra Singh and Professor Udo Schwingenschlögl discuss the gassensing ability of monlayer PtSe2
advantageous for gas sensing,” says Schwingenschlögl, adding that this material had not previously been considered for this purpose. This approach shows the interaction between monolayer and gas molecules at both structural and electronic levels. First, the researchers built a model monolayer composed of selenium atoms that formed octahedral arrangements with one platinum atom at their center. Next, they determined the optimal geometry adopted by individual gas molecules, such as NOX, NH3, H2O, CO2 and CO, upon adsorption. They assessed the capacity of these
adsorbed molecules to transfer charge to the monolayer by examining adsorptioninduced changes in the electronic properties. These calculations provided high adsorption energies, indicating strong affinity between monolayer and gas molecules. All adsorbed molecules altered the monolayer charge, which is key for the gas-sensing ability of monolayer PtSe2. Furthermore, their interactions were more effective with monolayer PtSe2 than its MoS 2 or carbon-based graphene analogues. “It’s exciting to explain this difference at a molecular orbital level,” says Schwingenschlögl. Calculations of electron transport revealed the high sensitivity of monolayer PtSe2 as a gas sensor. Schwingenschlögl explains, “We are currently looking for experimental collaborators to implement our concept.” Sajjad, M., Montes, E., Singh, N. & Schwingenschlögl, U. Superior gas sensing properties of monolayer PtSe2. Advanced Materials Interfaces 4,1600911(2016).
Efficiency gains come from tuning the properties of semiconducting materials by combining layers of different composition. A thin-film chemical sensor coated onto an electrode offers a simple, practical way to detect minute traces of toxic gas. Sensors that use metalorganic frameworks (MOFs) can be highly selective for a particular gas because of the porous nature of these crystalline materials and their nanoscale cavities. The electronic characteristics of an interface between two wide bandgap semiconductors are determined by researchers at KAUST: an insight that will help improve the efficiency of light-emitting and high-power electronic devices. Semiconductors, such as silicon and gallium nitride, have electrical properties somewhere in between those of a conductor and an insulator. They only allow current to flow when electrons have enough energy to overcome a barrier known as bandgap. The bandgap—which may be direct or indirect, narrow or large—determines the properties of semiconductors and their consequent applications. Materials with a large bandgap, for example, are useful in high-power electronics because they have larger breakdown voltage for energy-efficient transistors as compared with narrow bandgap materials, such as silicon. They can also produce light deep into the ultraviolet part of the spectrum, making them useful for disinfection and water purification. These materials can be further tailored to a specific application by layering different semiconductors on top of each other to create a so-called heterostructure with the desired properties. But it is vital to understand how the bandgaps of two semiconductors align when semiconductors are brought together in this way. Haiding Sun and principle investigator Xiaohang Li from KAUST and coworkers from the Georgia Institute of Technology, USA, report that they experimentally measured the alignment of two emerging large bandgap materials: boron aluminum nitride and aluminum gallium nitride. The 2014 Nobel Prize for physics was awarded in recognition of the development of gallium nitride
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light-emitting diodes. But, compared to gallium nitride, aluminum nitride has a much larger bandgap of 6.1 electronvolts. Its electronic properties can be tuned by replacing some of the aluminum atoms in the crystal with either boron or gallium. The team created an interface between boron aluminum nitride with a boron to aluminum atom ratio of 14:86 and aluminum gallium nitride with a gallium nitride ratio of 30:70 on an aluminum-nitride-covered sapphire substrate. They used high-resolution X-ray photoemission spectroscopy to measure the offset between the top and the bottom of the two material’s bandgaps. They show that the bandgaps have a staggered alignment, with both the top and bottom edge of the bandgap of the Al0.7Ga0.3N lower than the respective edge in B0.14Al0.86N. “Based on the experimental results, we can achieve a much higher amount of two-dimensional electron gas sheet carrier concentration in such junction,” says Sun. “The determination of the band alignment of B0.14Al0.86N/ Al0.7Ga0.3N heterojunction provides valuable support in the design of optical and electronic devices based on such junctions.” Sun, H., Park, Y. J., Li, K.-H., Torres Castanedo, C. G., Alowayed, A., Detchprohm, T., Dupuis, R. D. & Li, X. Band alignment of B0.14Al0.86N/Al0.7Ga0.3N heterojunction. Applied Physics Letters 111, 122106 (2017).
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Membranes of MXene have potential for water purification.
USING SUNLIGHT TO THE MAX A floating membrane that uses sunlight to evaporate water shows potential for water purification.
B E S E Materials called transition-metal carbides have remarkable properties that open new possibilities in water desalination and wastewater treatment. A KAUST team has found compounds of transition metals and carbon, known as a MXenes but pronounced “maxenes,” can efficiently evaporate water using power supplied by the sun. PhD student Renyuan Li has investigated a MXene in which titanium and carbon combine with the formula Ti3C2. “This is a very exciting material,” says Peng Wang, Li’s supervisor at the KAUST Water Desalination and Reuse Center. Wang explains his excitement comes from their finding that Ti3C2 can trap the energy of sunlight to purify water by evaporation with an energy efficiency that is state of the art. He says this clearly justifies more research toward practical applications. Other researchers had explored the ability of MXenes to act as electromagnetic shielding materials due to their ability to absorb wavelengths of electromagnetic radiation beyond the visible range. So the KAUST discovery began with a simple question: “We decided to investigate, what is the interaction with this MXene and sunlight?” With Wang’s group focused on desalination technology, using the sun’s energy to convert water into steam was an obvious target. The team’s first observation was that Ti3C2 converts the energy of sunlight to
heat with 100% efficiency. Also important, however, was that the sophisticated system developed during this research to measure light-to-heat conversion showed that various other materials, including carbon nanotubes and graphene, also achieved almost perfectly efficient conversion. “I suggest the focus of the field should now move away from finding new photothermal materials toward finding applications for the many perfect ones we now have,” says Wang. To investigate MXene’s possibilities in water purification, the researchers then fabricated a thin and flexible Ti3C2 membrane, incorporating a polystyrene heat barrier to prevent the heat energy from escaping. This created a system that could float on water and evaporate some of the water with 84% efficiency at the illumination levels of natural sunlight. For Wang, the next challenge is how to move from this basic research finding toward practical applications. Wang hopes to break through what he calls “the 85% efficiency barrier,” taking photothermal purification of water into new territory. In addition to maximizing the system’s light-trapping capacity, the researchers want to investigate ways to capture the water vapor and yield a complete water purifying process. Wang is already in talks with one potential industrial partner. Li, R., Zhang, L, Shi, L. & Wang, P. MXene Ti3C2: An effective 2D light-to-heat conversion material. ACS Nano 11, 3752-3759 (2017).
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KAUST researchers are evaluating the resilience and persistence of species living in the Red Sea in the face of climate change and human-induced stresses. Their scientific discoveries allow them to formulate the most effective management plans to conserve resources the Red Sea provides to the region.
PROTECTING MARINE ECOLOGY Learn more DISCOVERY.KAUST.EDU.SA
INNOVATION THROUGH V ISUA L IZ ATION
VISUALIZATION HELPS SCIENCE TO SEE THE UNEXPECTED There’s a certain beauty to data. Whether it’s an infographic on research collaboration or a complex map of genomic data, the interplay between variables is often better appreciated from a visual display than from a table of numbers. But the utility of these tools goes beyond the production of aesthetically pleasing graphs. Enabled by more powerful technology, scientists at KAUST are increasingly considering how graphic
Visualization as a core analytical tool Daniel Acevedo-Feliz, former Director of the Visualization Core Lab, says their work helps scientists to “see the unexpected,” through audiovisual experiences that literally immerse researchers in their data and understand it in a new way. For example, one group of researchers approached the lab staff with their model of salt deposition in turbulent waters. When scientists in the lab recreated the model on-screen, the researchers realized they had
KAUST / XAVIER PITA
Advances in how science is presented means that visual tools can inspire research, as well as make its results accessible to the world.
analysis can benefit their studies. KAUST’s Visualization Core Laboratory is home to state-of-the-art visualization, interaction and computational resources that allow researchers to present and explore scientific data. Their expertise is anchored in data analysis and visualization, both key elements of the scientific process, enabling researchers to evaluate their experiments and to ask new questions that could lead to discoveries.
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Diving into science With the advent of high-definition virtual reality, scientists now have the ability to get up close and personal with their research. “One of the key elements we use is not just the visuals but interaction,” says Acevedo-Feliz, describing how the researchers utilize the KAUST Virtual Reality (VR) advanced facilities. “They use interaction as the main tool for them to discover potentially interesting things. They get the data from the microscopes, slice it, reconstruct it and then come to the Visualization Lab to use the VR facilities because this provides them that extra insight into complex phenomena.” “Changing the perspectives also changes the way scientists approach the data,” says Acevedo-Feliz. In this way, visualization transcends being just a way to display research, to be a real tool for discovery. With VR, visualization can take data from the wall or the page and bring it to life in 3D. Taking science from the page to the public While the primary focus of the Visualization Core Lab is to facilitate the work of academics, Xavier Pita then takes this and distils the key elements into a medium that can be easily understood by nonspecialists. “It’s an important
Science as art, art as science Offering a different viewpoint is Tamara Jones, a freelance artist residing at KAUST. As she puts it, hers is the world of shape, form and proportion. While Jones’ art and the visuals of Pita and Acevedo-Feliz may not be directly related, they all agree that they use the same fundamental palette. They rely on the judicious use of shape and color, and most importantly, they work to convey message and meaning to their target audience. Each perspective represents a different, yet highly important step in the process of discovery, explains John Tannaci, KAUST’s Director of Research Operations. Jones explores what’s out there to be looked at, Acevedo-Feliz explores these things to find new research directions, and Pita helps to convey the science to audiences in the most accessible way possible.
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overlooked a potentially important aspect of how the process works in the real world. Visualization can also be used to validate research, as was the case with Ibrahim Hoteit, whose researchers brought their storm model to the Visualization Core Lab, where the team used it to simulate a real storm from 2015 and compare it to how the storm actually played out on satellite imagery. “We put them side-by-side…and it really tracked. It was in the position that it actually happened. That was a good result,” says Acevedo-Feliz.
step—to get that information to the audience,” he tells the audience. “We feel that communication is more efficient—more effective—if people are drawn into it;” highlighting the importance of having a clear, immediate message. “Is it readable? Understandable? Can it stand on its own?” The process of constructing the perfect scientific illustration is highly collaborative. Offering an inside view into his process, Pita describes collaborating with a research colleague to produce an image that contrasts plant growth and water evaporation with and without the use of water-repelling sand. As the scientist explained the process, Pita would translate the words into imagery on paper. Acevedo-Feliz agrees with the importance of collaboration: “They [the scientists] give me a USB stick and say ‘visualize that’—and I’m like ‘no, I can’t! I don’t know what that means.’”
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INNOVATION THROUGH V ISUA L IZ ATION
A new computational framework marries ideas from computer graphics with civil engineering to reduce times and costs of constructing frame-based structures.
STREAMLINING SPACE
C E M S E Space structures can take many forms—from pylons and bridges to public buildings, such as a train station (see image). These constructions consist of metal beams that converge at nodes to create a geometrically repeating, freestanding structure. A KAUST-led research group has developed a framework that could reduce construction time and the total volume of building materials.
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“We want space structures to be statically sound, aesthetically pleasing and reflect the architect’s desired design,” says Chengcheng Tang, former KAUST PhD student who is now a postdoctoral researcher at Stanford Universit y. “Most importantly, we want to minimize the construction cost. The volume of the material used for making the required beams is one of the most significant costs.” “Together, this presents a
complex formula that’s difficult to solve, so we broke it down into more easily managed subproblems,” adds Caigui Jiang, lead author of the group’s paper, also a KAUST PhD alumnus, now a postdoctoral researcher at the Max Planck Institute for Informatics. Jiang and his team created a framework that can generate a structurally sound space frame while also calculating an ideal set of beam thicknesses and assigning
them where needed. “Our algorithm can automatically assign thick beams in sections with strong tension or compression forces,” explains Jiang. This objective assessment means that superfluous beams are not assigned, thereby reducing material wastage. The first example of it’s kind, this algorithm completes its calculation much faster than any existing framework. Current techniques mandate a multistep
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process, whereby algorithms produce a half-finished design that must be manually refined by engineers, further adding to design time and resource requirements. Jiang and Tang’s research brings together two seemingly disparate fields: computer graphics and civil engineering. W hile the former operates in a space
largely unaffected by realworld forces and constraints, its researchers are increasingly bridging the gap into the physical world: “Many people in the computer graphics community are starting to work on structural
Using a new computer framework, the design and construction of space structures, such as this train station model, is a faster and less costly affair.
“We want space structures to be statically sound, aesthetically plea sing and reflect the architect ’s desired desig n,”
engineering problems,” says Tang. “More recently, this community has also started to push the physical realization of digital design, such as in abstract furniture and 3D printing.” In the future, says Jiang, they could attempt to integrate more physical considerations into their framework. Also, Tang hopes to investigate existing constructions as a source of data that, when combined with computational design methods, could
be used to inform engineering projects. Research leader Peter Wonka explained that both Jiang and Tang had been students in the Visual Computing Center. “It was exciting to see them grow over the course of their PhD studies to become excellent researchers in the area of visual computing,” says Wonka. Jiang, C., Tang, C., Seidel, H-P. & Wonka, P. Design and volume optimization of space structures. ACM Transactions on Graphics 36, 159 (2017).
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An underwater wireless optical communications system for streaming high-quality, live video. C E M S E A flexible and cost-effective technology for streaming high-quality underwater video images has been developed
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by researchers at KAUST by improving the bandwidth to achieve better video quality. Oceans cover more than two-thirds of our planet and are a major source of
like acoustic communications and low-frequency radio waves are limited by narrow bandwidths and the need for large antennae and high-transmission powers, making them unsuitable for streaming good-quality, realtime video. PhD student Abdullah Al-Halafi, with his supervisor Basem Shihada and colleagues, explored underwater wireless optical communication (UWOC) systems, which consume significantly less power and offer the higher bandwidths required for streaming live video. “We first built the real-time video transmission system
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biodiversity, food and medicines as well as containing vast reserves of oil, gas and marine aggregates for use in many industrial processes. Wireless technologies that are capable of producing realtime video have the potential to open the oceans to further exploration and monitoring. They will be particularly useful for the inspection and maintenance of underwater pipelines and cables and of offshore oil and gas fields, where waters are too shallow for remotely operated vehicles and where the use of divers is often impractical and costly. Existing technologies
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Abdullah Al-Halafi and Professor Shihada check the received optical signal power through the underwater channels.
and then integrated it into an UWOC setup,” explains AlHalafi. “Although the design and development of the system were very challenging, its ability to be programed enabled us to reconfigure the system into several different arrangements.” To improve the accuracy of the detected signal, the researchers first used a technique called quadrature amplitude modulation to increase the representation of information carried by the signal for a given bandwidth. They then compared it with phase-shift keying, which changes the phase of the carrier signal, while optimizing
the transmission for each configuration.
“Our system produced the highestquality video streaming so far achieved in UWOC systems.” To check how well the system performed, the team developed an innovative algorithm to measure errors that occur during transmission called the bit error rate. Also, by passing the signal through a five-meter trough containing water of differing turbidity, they were able to test the quality of the video under different types of ocean water. “Our system produced the highest-quality video streaming so far achieved in UWOC systems and provides a reconfigurable and cost-effective communications system for underwater live video streaming,” says Al-Halafi. “It could lead to advances in underwater research and the discovery of new resources.”
3D PARTICLE TRACKING? THERE’S AN APP FOR THAT Smartphones put state-of-the-art 3D particle tracking in the hands of the masses.
P S E Using four low-cost smartphone cameras and some simple colored backlighting, KAUST researchers have dispensed with expensive research-grade camera equipment and dangerous lasers to construct a tomographic particle image velocimetry (PIV) system that is capable of quantitative flow visualization. The proof-of-concept study demonstrates the research power of everyday devices, and puts a state-of-the-art tool within easy reach of a broader group of researchers and educators.
Al-Halafi, A., Oubei, H. M., Ooi, B. S. & Shihada, B. Real-time video transmission over different underwater wireless optical channels using directly modulated 520 nm laser diode. Journal of Optical Communications and Networking. 9 (10) 826-832 (2017).
An example of the threecolor tracer particle image captured using a smartphone for tomographic particle image velocimetry measurements.
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Tomographic PIV is regarded as the Holy Grail of experimental fluid mechanics: it allows flow fields to be observed in 3D at fine spatial resolution by tracking the motion of tracer particles using an array of digital cameras. The technique involves lighting up the fluid volume with a high-intensity laser and recording the light scattered by the tracer particles using expensive, high-speed, high-sensitivity cameras. These images are then processed by simple tomographic reconstruction algorithms to reproduce the position of the particles and track their motion over time to give the 3D velocity field. “Having access to tomographic PIV for the first time allows the calculation of full vortex structures in a turbulent flow,” says Sigurdur Thoroddsen who led the research team. “This can benefit many applications involving turbulence, such as mixing or reducing drag for flows over airfoils or Formula 1 cars and even studying swimmers and flying animals. “But the technique is
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prohibitively expensive for many researchers,” continues Thoroddsen. “We believe that it should be possible to use mainstream consumer devices to produce high-quality research on various flow problems.” The smartphone PIV system consists of four 41-megapixel smartphone cameras positioned at different angles around the flow volume—in this case a glass tank filled with moving water and polystyrene tracer particles that form a vortex ring flow. To overcome the low sensitivity of the phone cameras, the cameras were set up to photograph the shadows of the tracer particles cast by blue, green and red LED lights, imprinting in the same image all three colors. “With the addition of optical zoom as seen on some of the latest phones and the ability to take ‘4k’ video clips or even slow-motion video, we expect to see a significant increase in the possibilities of this approach,” says Thoroddsen. “We have already pre-ordered the latest phones to extend our work.” Aguirre-Pablo, A., Alarfaj, M. K., Li, E. Q., Hernández-Sánchez, J. F. & Thoroddsen, S. T. Tomographic particle image velocimetry using smartphones and colored shadows. Scientific Reports 7, 3714 (2017).
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The researchers acquired incredible images, such as this one, showing a jet flame being affected by a 16-kV electric field between two electrodes.
GAZING INTO THE FLAMES OF IONIC WINDS New 3D visualizations that reveal how flames respond to electric fields could help improve combustion efficiency and reduce pollution.
P S E The ability to precisely control flames could lead to greater energy efficiency and fewer harmful emissions from transport and industry. Flames contain charged ions and electrons, which can be manipulated using electricity. KAUST researchers have now produced the first detailed 3D visualizations of ionic winds flowing from a flame in response to both direct (DC) and alternating (AC) electric fields. Mechanical engineer Minsuk Cha and coworkers previously developed a theoretical model explaining how ions in a flame respond to electric fields. For their latest work, the researchers ejected a mixture of methane and air through a jet flame nozzle positioned between two electrodes. They illuminated the flame using an argon-ion laser and detected the scattered light in order to trace the motion of individual particles through the flame—a technique called particle image velocimetry or PIV. To improve this visualization, they had to add to the flame reflective seeding particles made from titanium oxide and oil. “The particle seeding to the ambient flame was quite difficult,” says Cha. “We used a smoke generator, but we had to control the timing of the smoke generation very carefully so that we didn’t disturb the main flow.” The researchers acquired images that reveal unprecedented details of how flame
dynamics respond to electricity. When they used a DC field, the flame visually bent towards the negative electrode because positive ions (which vastly outnumber negative ions in the flame) were attracted that way. Counterintuitively, however, the ionic wind blew toward both electrodes, indicating an important role for negative ions. In an AC field, the ionic wind dynamics depended on the applied AC frequency, though only at low frequencies. These ionic winds could influence the combustion process by allowing a controlled redistribution of heat and combustion products by convection. Cha hopes that this work could have a positive impact on the future design of flame-generating machinery. Most importantly, it wouldn’t require the building of completely new industrial equipment. “The beauty of this method is that it can be retrofitted—it can be added in as an active control method for any pre-existing combustion system. Depending on the system configuration and the type of combustion that we need to control, we could use our knowledge and understanding to work out the appropriate locations of electrodes and choose the best operational parameters, such as voltage or frequency.” Park, D.G., Chung, S.H. & Cha, M.S. Visualization of ionic wind in laminar jet flames. Combustion and Flame 184, 246-248 (2017).
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PhD student Nada Al-Jassim tests to verify if solar irradiation can be used to kill E.coli strains in wastewater.
SUNNY SOLUTION FOR KILLING E. COLI Treating wastewater with solar irradiation shows promise in reducing two E. coli strains but a resilient strain persists. B E S E Increasingly virulent strains of Escherichia coli are circulating in wastewater around the world, and the race is on to find novel treatment processes that could help reduce the spread of these pathogens. KAUST researchers examined how three strains of E. coli found in Jeddah’s wastewater supply fared when placed under strong sunlight: they showed, while two strains were reduced, one strain persisted. “Solar irradiation is used
unintentionally in many places when treated wastewater is stored in an evaporation pond prior to reuse or when it is used to irrigate crops in daylight,” says Pei-Ying Hong, who led the project with PhD student Nada Al-Jassim and coworkers at KAUST’s Water Desalination and Reuse Center. “However, because this approach is unintentional, it is difficult to know how successful it has been. We therefore decided to analyze what happens to E. coli in wastewater under solar irradiation.” Sunlight is known to kill pathogens in freshwater. In fact, as Hong notes,
nongovernment organizations recommend that rural communities with no treatment for basic drinking water should store their water in transparent plastic bottles, and that they place these bottles in direct sunlight for some hours before consumption. Hong’s team used a similar idea; they prepared two reactors each carrying a strain of E. coli—a recently discovered, highly antibiotic-resistant strain called PI-7, and a common, nonvirulent strain called DSM1103. These reactors were subjected to solar irradiation for 24 hours, while two identical reactors were stored in the dark as controls. The team took samples at regular intervals from the four reactors and analyzed changes to the genetic make-up and the survival rates of each strain of E. coli. “The viable cell counts of both strains reduced considerably, but E. coli PI-7 decayed at a slower rate compared to DSM1103,” says Hong. “Rather worryingly, and unlike DSM1103, PI-7 formed ‘persister’ cells in the later stages of prolonged solar exposure. This means a small portion of PI-7 cells can withstand solar treatment and regrow again when the environmental conditions become favorable.” PI-7 defended itself against solar irradiation by upregulating genes related to cellular repair and oxidative stress, along with various virulence factors. However, during the genetic analysis, Al-Jassim noted with interest that genes carried by PI-7 to protect it from viruses were downregulated during solar irradiation. “I’m now working on isolating these viruses, known as bacteriophages, in the hope that they could be used to increase the susceptibility of PI-7 toward solar irradiation,” says Al-Jassim. “By using both bacteriophages and solar irradiation at the same time, such antibiotic-resistant strains might be more easily killed off.” Al-Jassim, N., Mantilla-Calderon, D., Wang, T. & Hong, P-Y. Inactivation and gene expression of a virulent wastewater Escherichia coli strain and the nonvirulent commensal Escherichia coli DSM1103 strain upon solar irradiation. Environmental Science and Technology 51, 3649–3659 (2017).
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MARINE RESERVES OFFER PROTECTION Protection zones for coasts and oceans are an effective way to help marine and human communities to adapt to climate change. B E S E Marine protected areas (MPAs) that restrict or ban extractive activities, such as fishing or mining, play a wellestablished role in conserving biodiversity. An international research team suggests that such reserves, when managed effectively, will be vital in helping marine communities adapt to the impacts of climate change. The team says that formal protection of marine ecosystems will support the biological processes that will help make these areas resilient to disturbances from a changing climate. Scaling up through an extensive network of MPAs can multiply these benefits. The global community has procrastinated too long about greenhouse emiss i on s , e x p l a i n s C a r l o s Duarte, the director of the Red Sea Research Center at KAUST. “Even if the 2015 Paris Agreement on climate change is fulfilled in its most ambitious form, mitigation will come too late to halt the impacts of climate change on tropical coral reefs and Arctic
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ecosystems and the communities and societies that depend on them for their livelihoods,” he explains. For marine ecosystems, impacts of climate change are increasingly understood to include acidification, sea-level rise, more intense storms, shifts in species distribution, and decreased productivity and oxygen availability. The interactions and cumulative effects of these are also significant. Many of these impacts are evident already. “Loss of Arctic sea ice is already severe and irreversible on managerial time scales—where our ability to manage it can make a difference,” Duarte says. “Sealevel rise is already accelerated so that, even if CO 2 emissions and atmospheric levels are controlled, the seas will
“Sea-level rise is already accelerated so that even if CO 2 emissions are controlled, the seas will continue to rise for several centuries and affect low-lying coastal areas worldwide.”
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For instance, D uarte describes how conserving coastal vegetation, such as mangroves and seagrass meadows, helps these ecosystems and associated biota to mitigate and adapt to climate change. “They deliver huge benefits to coastal societies as mangroves and seagrass can help protect these coasts from sea-level rise and increased storm surges.”
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For Duarte, conserving mangroves would be essential to protect against sea-level rise and an increase in the frequency and severity of storms.
continue to rise for several centuries and affect low-lying coastal areas worldwide.” “Plus, many coral reefs are already near their thermal thresholds and may suffer severe impacts even at warming targets below those established under the Paris Agreement.”
Vulnerable seagrass meadows would benefit from reducing stressors, such as disturbance from anchors and reduction of nutrient-rich runoff from adjacent land.
Duarte and colleagues suggest that MPAs can help to increase carbon sequestration and storage to reduce greenhouse gases. Also valuable is the role of MPAs in buffering these ecosystems against environmental fluctuations and extreme events likely with a changing climate.
Duarte reports that this work is already stimulating international discussion around how to increase the extent of MPAs across the globe. New information is needed however. MPAs have historically been developed for conservation objectives, and so we need new information about appropriate design, meaning their extent, boundaries and location, to help maximize benefits in terms of climate change. Roberts, C.M., O’Leary, B.C., McCauley, D., Cury, P., Duarte, C.M. et al. Marine reserves can mitigate and promote adaptation to climate change. Proceedings of the National Academy of Sciences 114, 6167-6175 (2017).
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A global city in Saudi Arabia
Hydrogen is abundant, predominantly in the form of water: inexpensive, effective catalysis would underpin an oxygen evolution revolution.
SPLITTING WATER FOR THE COST OF A NICKEL A simple treatment of nickel to make it an efficient catalyst for water splitting. P S E
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A technique to create a material for costeffective water electrolysis uses a simple chemical method for preparing nickelbased anodes to improve the oxygenevolution reaction. Efficiency gains like this one developed by KAUST are important in evolving renewable energy. Hydrogen stores a tremendous amount of energy and so offers great potential as a sustainable, carbonfree source of power. Hydrogen is also abundant on Earth, although predominantly in the form of water. Electrocatalysis can separate the hydrogen atoms from the oxygen atoms, but a crucial consideration is a process known as oxygen evolution. The rate of oxygen creation is known to affect the overall production rate of hydrogen; thus, scientists are searching for a catalyst to enhance this reaction. Noble metals, such as iridium and ruthenium, have excellent oxygenevolution performance but are very expensive. As a cheaper alternative, PhD student Tatsuya Shinagawa and internship student Marcus Ng were guided by Associate Professor Kazuhiro Takanabe from the KAUST Catalysis Center to use a simple chemical method
to improve the oxygen-evolution reaction. The team’s protocol involves repeated redox cycling of nickel in a carbonate or phosphate electrolyte at moderate pH and temperature of approximately 55°C and the evaluation of the water-splitting process performance at elevated temperatures (up to 80°C) Imaging the resultant nickel electrode with a scanning electron microscope indicated that the fabrication process restructures the surface to create a layer of nickel-oxide hydroxide more than onemillimeter thick. The 3D structure of this layer can trap weakly bound alkali-metal cations and water. The new electrode exhibited greatly superior oxygen-evolution reaction performance compared to nickel-iron oxide under near-neutral pH conditions and at temperatures commonly used in industrial processing. “We hope to follow this study by building a further understanding of the material’s properties and its performance,” says Shinagawa. Shinagawa, T., Ng, M. T.-K. & Takanabe, K. Boosting the performance of the nickel anode in the oxygen evolution reaction by simple electrochemical activation. Angewandte Chemie 56, 5061(2017).
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THE FUTURE OF AGRICULTURE Learn more DISCOVERY.KAUST.EDU.SA
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Food security is an increasingly important challenge for Saudi Arabia and the world. KAUST’s location on the coast of the Red Sea and in the desert gives our researchers the motivation and the opportunity to focus on identifying the genes in plants that promote tolerance for high salinity and drought. If we are able to grow food in difficult environments, the impact on global food security could be significant.
Researchers at KAUST are focusing on optimizing the storage and conversion of solar energy where sunlight is abundant but high temperatures and dust reduce the efficiency of solar panels. Using the energy of the sun and innovative materials, our scientists work toward contributing new technologies that offer cheaper, cleaner and more efficient solutions.
SUNLIGHT AS POWER Learn more DISCOVERY.KAUST.EDU.SA