KAUST Discovery - Issue 7 by KAUST

ISSUE 7 / SPRING SEMESTER 2019

Q U A N T IF Y ING R ED S E A PL A S T IC S F ROM C O A S T S T O F I S H P.6

3D -PR IN T ED CUBE DI A L S IN T O ENERGY H A R V E S T ING P.32

B A SK ING IN A Q U A N T UM EF F ICIENC Y GL O W P.50

PUTTING THE SENSE IN M AT E R I A L S P.39

Core Labâ&#x20AC;&#x2122;s Centers of Excellence

Providing state-of-the-art facilities, training and services to KAUST faculty, students, collaborators and industrial partners.

Driving efficiency to deliver greater impact for a more collaborative environment with the One-Lab Model.

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EDITOR’S NOTE Dear Reader, At the beginning of September, we welcomed our new president, Dr. Tony Chan, who joined us from Hong Kong University of Science and Technology. We are eager to work under President Chan’s leadership and to learn about his strategic vision for the University as it continues to play an important role as a catalyst for change in Saudi Arabia and the world. In this issue, we highlight the University’s research in the field of sensors. Our feature story examines the challenges that motivate the research of several of our sensor experts. From designing sensors that flex with human motion to developing sensors that can sustain function under deep-sea pressures, our experts work to optimize sensor capacity and efficiency. We hope that you enjoy reading about the research of two of Professor Carlos Duarte’s students, who each study the accumulation of marine plastics at very different scales. Cecilia Martin describes how she uses algorithms to train drones to recognize plastic debris on the beach. Her technique is 40 times more effective than the standard visual approach for quantifying plastic litter along beaches. Meanwhile, Fadiyah Balkhuyur reports her shocking findings that microplastics are found in the guts of one in every six Red Sea fish. The story that weaves these two complementary works together reminds us of the value of investigating a problem on multiple scales—in this case, from the micro scale to the bird’s-eye view. In the not-so-distant future, you might be carrying one of Professor Atif Shamim’s 3D-printed energy-harvesting cubes in your pocket. This cube grabs radiofrequency waves from the environment and uses them to power wireless sensor nodes. His team envisages that their energy

harvester may help to accelerate progress of the Internet of things, with self-powered, low-cost, long-lasting sensors. Meanwhile, Assistant Professor Derya Baran, who recently received an MIT Technology Review award for Innovators under 35, is developing printing ink that can efficiently capture sunlight. Baran and her team picture a city filled with buildings that incorporate windows and other building materials coated in their photovoltaic ink. We hope that you enjoy reading our latest stories of discovery and that you share them with your friends, family and colleagues. For a weekly helping of

“F r o m d e s i g n i n g s e n s o r s that flex with human motion to developing sensors that can sustain function under deep-sea pressures, our experts work to optimize sensor c a p a c i t y a n d e f f i c i e n c y .” KAUST Discovery, visit our website— discovery.kaust.edu.sa—and keep up to date with our new stories by signing up for our fortnightly newsletter. Carolyn Unck Managing Editor

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CONTENTS / SPRING 2019

ABOUT THE COVER

A 3D energy-harvesting cube that grabs radiofrequency waves from the environment and converts them to electrical energy.

EDITORIAL COMMITTEE Pierre Magistretti Dean, Biological and Environmental Science and Engineering Division

If you would like to update your information, send us an email at discovery@kaust.edu.sa

Mootaz Elnozahy Dean, Computer, Electrical and Mathematical Sciences and Engineering Division Magnus Rueping Professor, Chemical Science Physical Science and Engineering Division

MANAGING EDITOR Carolyn Unck EDITORIAL TEAM Carmen Denman Virginia Unkefer ILLUSTRATIONS AND PHOTOGRAPHY Helmy Alsagaff Dylan Finol Ivan Gromicho Heno Huang Anastasia Khrenova Xavier Pita

KAUST DISCOVERY is published for 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 239556900 â&#x20AC;&#x201C; Kingdom of Saudi Arabia Email: discovery@ kaust.edu.sa

Published by Nature Research Custom Media, part of Springer Nature for King Abdullah University of Science and Technology (KAUST).

O N T HE C OV ER

QUANTIFYING RED SEA PLASTICS FROM COASTS TO FISH

3D-PRINTED CUBE DIALS INTO ENERGY HARVESTING

BASKING IN A QUANTUM EFFICIENCY GLOW

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CONTENTS / SPRING 2019

R ED S E A S C IEN C E

C L IM AT E C H A N G E

WAT ER B R E A K T H RO U G H S

S M A R T T EC H

26 ROBOTS LEARN BY CHECKING IN ON TEAM MEMBERS

Innovative drone designs and software enable a team of drones to work together in a coordinated approach.

28 LINING MOF POCKETS TO DETECT NOXIOUS GASES 14 HOW EXTREME WEATHER EXACERBATES AIR POLLUTION 6 QUANTIFYING RED SEA PLASTICS FROM COASTS TO FISH

While drones scan beaches to assess plastic litter, microplastics are found in the digestive tracts of one in every six Red Sea fish.

8 THE EFFECTS OF OIL POLLUTION ON P HYTOPLANKTON P OPULATIONS

An examination of the sensitivity of phytoplankton communities to oil pollution in the Red Sea provides crucial baseline data on toxicity.

10 CRYPTIC CORAL REEF CREATURES SHOW CROSS-SHELF BIODIVERSITY PATTERNS Composition in cryptic fauna assemblages changes across a shelf gradient, a recent study of the Red Sea shows.

12 NOVEL CARBON SOURCE SUSTAINS DEEPSEA MICROORGANISM COMMUNITIES

A carbon source stemming from daily fish migrations is implicated in the global carbon cycle.

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Simultaneously modeling air pollutants and weather under extreme conditions highlights the potential for serious health risks.

15 CORAL TRICKS FOR ADAPTING TO OCEAN ACIDIFICATION

A molecular process that signals distress could also help corals adapt to climate change.

16 REMOTE CORALS PAY THE PRICE OF CLIMATE CHANGE

Corals, even in the most far-flung locations, are being affected by climate change but fare better in marine protected areas.

18 RED SEA FLUSHES FASTER FROM FARFLUNG VOLCANOES

Volcanic eruptions in Mexico and the Philippines can lead to atmospheric changes that favor the ventilation of deep water in the Red Sea.

19 KEEPING UP WITH SEA-LEVEL RISE

Maintaining a balance between rising sea levels and soil accumulation will rely on careful management of coastal regions.

Custom-made gas-sensing material could lead to inexpensive devices for realtime air-quality analysis.

21 WATER DESALINATION PICKS UP THE PACE A membrane made of porous carbon-fiber structures grown on a porous ceramic substrate is more efficient efficient than similar exisiting membranes at filtering seawater.

30 CONTROLLING THE CRYSTAL STRUCTURE OF GALLIUM OXIDE

Precise control of the atomic structure of gallium oxide layers improves the development of high-power electronic devices.

22 REUSING WATER TO GROW QUALITY FOOD IN CITIES

32 3D CUBE

25 BIO-INSPIRED MATERIALS DECREASE DRAG FOR LIQUIDS

34 SMART SKIN FOR FLEXIBLE MONITORING

Research to optimize aquaponics systems could inform a new era of urban food production.

Tiny nature-inspired cavities that trap air can stop liquids from sticking to surfaces without the need for coatings.

Ambient energy emitted by cellular phones and modems can be captured and converted into electricity using unusually shaped technology.

An electronic tag that stretches and flexes while it records location and environmental data can monitor marine animals in their natural habitat.

36 THE RAW POWER OF HUMAN MOTION

Standalone power modules that harvest and convert vibrations from their surroundings into electricity could soon fuel future microsystems.

37 ELECTRONIC SKIN STRETCHED TO NEW LIMITS A metal carbide within a hydrogel composite senses, stretches and heals like human skin for use in medicine and robotics.

CONTENTS / SPRING 2019

F E AT U R E

C L E A N ER F U EL S

IN N OVAT I V E B I OT EC H

S C IEN C E V I S UA L IZ ED

53 THE LONG AND SHORT OF DNA REPLICATION 45 PUTTING GAS UNDER PRESSURE

Understanding the response of gas flames to acoustic perturbations at high pressure should make next-generation turbines safer and more efficient.

46 THIN FILMS FOR MORE EFFICIENT SOLAR CELLS 39 PUTTING THE SENSE IN MATERIALS

An interdisciplinary initiative is helping KAUST be at the forefront of a digital revolution where sensors can find use just about anywhere.

Tantalum nitride as thin layers improves the extraction of electrons from silicon solar cells.

48 SIMPLE SWAP FOR A GREENER TOOLKIT

A metal catalyst that gives distinct carbon-based molecular skeletons upon ligand change may unlock cost-effective, green synthetic routes.

49 SOLAR FUELS WORKING WELL UNDER PRESSURE Computer analysis aids the formulation of methanol-based renewable fuels that can operate under compression ignition conditions.

50 BASKING IN A QUANTUM EFFICIENCY GLOW Printable solar materials could soon turn many parts of a house into solar panels.

An unexpected two-step mechanism occurs when cells copy DNA.

54 THE DYNAMIC MOLECULAR CHANGES OF HOMING

Molecules reorganize to slow stem cells down, giving them a chance to adhere to and eventually cross the inner lining of blood vessels into the bone marrow.

55 DETECTING METABOLITES AT CLOSE RANGE Pairing a conjugated polymer with a redox enzyme generates a fast, selective and sensitive electrochemical biosensor for metabolites.

57 ENZYME ADOPTS DYNAMIC STRUCTURE TO FUNCTION IN HOT, SALTY SEA Protein analysis could lead to new advances in DNA sequencing technologies.

59 MINING RED SEA BACTERIA FOR INDUSTRIAL POTENTIAL

Genome sequencing of two Red Sea bacteria highlights their potential as industrial workhorses.

60 SOLVING REAL-WORLD PROBLEMS

A tool developed by Håvard Rue has transformed data analysis, interpretation and communication. It has been applied broadly: from modeling the spread of infectious diseases to mapping fish stocks.

62 SCANNING IN THE FOURTH DIMENSION

A novel imaging method makes it possible to capture object deformation in three dimensions over time with unprecedented accuracy.

63 ATTEMPTING TO TAME PLASMAS IN FUSION A numerical study reveals how to reduce instabilities in the complex flow of plasma.

63 TROUBLE ON THE SURFACE BEGINS WITH A WAVE OF TINY BUBBLES

Rapid-fire photography reveals how even a nanoscale amount of surface roughness can unleash microbubbles that may interfere with coating technology.

52 FUEL CHEMISTRY DISTILLED

A new conceptual model for describing a fuel’s composition can accelerate and simplify combustion simulations.

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RED SEA SCIENCE

Drones can scan beaches for plastic litter 40 times faster than the standard visual-census approach.

QUANTIFYING RED SEA PLASTICS FROM COASTS TO FISH While drones scan beaches to assess plastic litter, microplastics are found in the digestive tracts of one in every six Red Sea fish.

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As marine plastic pollution becomes an increasing concern worldwide, KAUST scientists report on two projects investigating plastic litter on and off the shores of the Red Sea. To investigate plastics on beaches, the team has developed a method, using unmanned aerial vehicles and machine learning, to improve the monitoring of large swathes of coastal areas for plastic litter1. “We know that we dump millions of tons of plastic in the sea every year, but we don’t know where this ends up,” explains marine science Ph.D. student Cecilia Martin. “One of the most influential scientists in the field of marine plastic pollution, Jenna Jambeck, from the University of Georgia, says we can’t manage what we can’t measure. So quantifying plastic on beaches is a key step to quantifying the whole of marine litter.” But such a count is painstakingly slow and inefficient. Current methods involve people walking and scanning small portions of accessible beaches, making it impractical for assessing global distribution patterns of plastic litter on our coasts. KAUST marine ecologist Carlos Duarte and colleagues from across the University tested the use of unmanned aerial vehicles (UAVs) for scanning larger portions of beaches faster than current approaches. The team conducted a standard beach survey of plastic

RED SEA SCIENCE

the surrounding tissues. Duarte led a second research project comprised of an interdisciplinary team of researchers from KAUST and King Abdulaziz University in Jeddah. This team reports that, despite remarkably low amounts of plastic in Red Sea surface waters compared to other semi-enclosed seas2, microplastics are found in the guts of one in every six Red Sea fish. This has implications not only for the health of the Red Sea ecosystem, but also for the people who consume these fish. The researchers collected 178 fish belonging to 26 species from four different marine habitats. Examination of their gut contents, showed that one in every six fish had ingested small pieces of plastic. This is comparable to findings from other marine ecosystems, despite previous KAUST research reporting that the Red Sea has the lowest amount of floating microplastics reported in seas around the world. “The major finding of this study is that microplastic pollution has reached our commercial and noncommercial fish species and might contaminate the fish we consume,” says master’s degree student, Fadiyah Baalkhuyur. “The surprising finding was the amount of ingested fibers originating from the degradation of plastic debris, such as those from packaging materials and from washing synthetic clothing. This might suggest that these fibers are spread out in all the marine habitats and might become a significant source of marine pollution in the Red Sea,” she adds. Fish could prove to be a major sink for the incredibly large amount of plastics that we use and throw away on a daily basis. The team is now setting up an experimental design to examine the process of microplastic uptake by fish under laboratory conditions, says Baalkhuyur. Cecilia Martin and Fadiyah Balkhuyur inspect fish guts for microplastics.

items and then compared the results with numbers of plastic items along the same area of beach by analyzing images taken by a UAV. They found that UAVs can scan beaches for plastic litter 40 times faster than the standard visual-census approach. Manual screening of UAV images taken from a height of ten meters was 62 percent accurate. The team then fed a computer with images of litter to train it to automatically detect plastics when provided with new images. This method led to an overestimation of the amount of plastic litter on the beach, but it was relatively accurate in its ability to identify the percentages of different types of plastic, such as drink containers, bottle caps and plastic bags. Despite its shortcomings, this method shows promise. Improvements can be made by using a higher-resolution camera on the UAV and by feeding the computer more image samples, Martin explains. The team from KAUST’s computer science department is already working on improving the algorithm. As much as 80 percent of plastic litter found in the oceans comes from land-based activities. Once plastics enter the ocean, they are dispersed by currents or sink to the seafloor, slowly breaking down into smaller components. Microplastics are pieces that are smaller than 5 millimeters. They are often ingested by marine life because they are similar in size to the prey of a large number of marine organisms. They can block or injure an animal’s digestive tract and can also have toxic effects when hazardous components leach into

1. Martin, C., Parkes, S., Zhang, Q., Zhang, X, McCabe, M.F. & Duarte, C. M. Use of unmanned aerial vehicles for efficient beach litter monitoring. Marine Pollution Bulletin 131, 662–673 (2018). 2. Baalkhuyur, F.M., Bin Dohaish, E.A., Elhalwagy, M.E.A., Alikunhi, N.M., AlSuwailem, A.M., Røstad, A., Coker, D.J., Berumen, M.L. & Duarte, C.M. Microplastic in the gastrointestinal tract of fishes along the Saudi Arabian Red Sea Coast. Marine Pollution Bulletin 131, 407–415 (2018).

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The effects of oil pollution on phytoplankton populations

S2 S3

An examination of the sensitivity of phytoplankton communities to oil pollution in the Red Sea provides crucial baseline data on toxicity.

S4 S5

S7 S8

Pyrene

Phenanthrene

Polycyclic aromatic hydrocarbons (PAHs) PAHs, including phenanthrene and pyrene, are highly toxic by-products of burning crude oil. PAHs can penetrate the tissues of organisms, interfering with biological processes and causing death. Pyrene is more toxic than phenanthrene.

Picophytoplankton Picophytoplankton, such as picoeukaryotes and synechococcus, are fundamental components of the marine food web: their disruption has a knock-on effect on all other marine life.

Sample Site

Oil Extraction

Shipping

Industry

TheThe RedRed SeaSea ecosystem ecosystem is unique. is unique. It has It has unusually unusually highhigh temperatures temperatures andand salinity salinity profiles profiles andand is is deficient deficient in major in major nutrients, nutrients, including including nitrates nitrates andand phosphates. phosphates. Contamination Contamination from from pollutants, pollutants, including including those those generated generated by the by the oil industry, oil industry, hashas been been shown shown to affect to affect marine marine organisms. organisms.

Summary Summary ofof Results Results North North S7

 LowLow nutrients nutrients

 LowLow abundance abundance of of phytoplankton phytoplankton

A SE D A RE SE D RE

 Picophytoplankton Picophytoplankton hashas a higher a higher tolerance tolerance to to oil pollution oil pollution

S9S9

South South  Higher Higher in nutrients in nutrients  High High abundance abundance of phytoplankton of phytoplankton  Picophytoplankton Picophytoplankton hashas a lower a lower tolerance tolerance to to oil pollution oil pollution

S 10S 10 S 11 S 11

A SE D EA RED S RE

S 12S 12

Key Key Findings Findings  Synechococcus Synechococcus is more is more tolerant tolerant to PAHs to PAHs

than than picoeukaryotes picoeukaryotes

 RedRed SeaSea picophytoplankton picophytoplankton areare more more tolerant tolerant to PAHs to PAHs than than similar similar planktons planktons found found in other in other oceans oceans  Picophytoplankton Picophytoplankton hashas a low a low tolerance tolerance to to oil pollution oil pollution Influx Influx of of water water fromfrom GulfGulf

Kottuparambil, S. & Agusti, S. PAHs sensitivity of picophytoplankton populations in the Red Sea. Environmental Pollution 239, 607-616 (2018).

RED SEA SCIENCE

CRYPTIC CORAL REEF CREATURES SHOW CROSS-SHELF BIODIVERSITY PATTERNS Composition in cryptic fauna assemblages changes across a shelf gradient, a recent study of the Red Sea shows.

Barcoding

Cryptic fauna—small organisms that inhabit the hidden spaces within a reef structure—represent a substantial proportion of the diversity within coral reefs but are typically neglected in traditional visual surveys, which tend to focus on large and conspicuous species, such as fish and corals. An international collaboration comprised of marine scientists from KAUST, the United States and Taiwan investigated the diversity patterns of the

Rabigh

Metabarcoding

>2000 μm

500-2000 μm

106-500 μm

5 km

Sessile

e d S

KAEC

a KAUST Thuwal

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Off-Shore

Mid-Shore

Near-Shore

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“R e s u l t s h a v e c l e a r implications for the design of marine p r o t e c t e d a r e a s .” cryptic fauna in eight reefs in the central region of the Red Sea. The distribution patterns of these small creatures was unraveled using autonomous reef monitoring structures (ARMS), which consist of stacks of plates creating an artificial three-dimensional habitat for colonization, in conjunction with amplicon sequencing methodologies. “Cryptic fauna have previously been revealed to show different responses to those organisms normally assessed in reef monitoring,” says lead author, John Pearman, from KAUST. “Therefore to effectively manage the biodiversity of coral reefs, it is important to understand how cryptic fauna vary across spatial scales

and how these organisms may respond to environmental changes.” Depending on distance from the coast, organisms experience changes in conditions, such as salinity, temperature, nutrients and sedimentation; all of which can have impacts on the distribution of those organisms and therefore in the composition of the ecological communities. “Our study shows that different reef habitats across the shelf are inhabited by different sets of species and are therefore relevant to regional diversity. These results have clear implications for the design of marine protected areas,” explains Pearman. Pearman, J.K., Leray, M., Villabos, R., Machida, R.J., Berumen, M.L., Knowlton, N. & Carvalho, S. Cross-shelf investigation of coral reef cryptic benthic organisms reveals diversity patterns of the hidden majority. Scientific Reports 8, 8090 (2018).

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RED SEA SCIENCE

NOVEL CARBON SOURCE SUSTAINS DEEP-SEA MICROORGANISM COMMUNITIES A carbon source stemming from daily fish migrations is implicated in the global carbon cycle. The first in-depth analyses of dissolved organic carbon (DOC) cycling in the Red Sea highlights the important role of migrating shoals of fish in sustaining deep-ocean microorganisms and potentially the global carbon cycle. The biological carbon pump is a cyclical process by which inorganic carbon from the atmosphere is fixed by marine lifeforms and transported through ocean

layers into the deepest waters and ocean sediments. Fish that feed at the surface at night and retreat to the mesopelagic zone (200 to 1000 meters depth) by day were thought to influence carbon cycling, but the extent of their contribution has never been explored. Now, Maria Calleja and Xosé Anxelu Morán at KAUST’s Red Sea Research Center, and coworkers, demonstrate the impact of this daily migration on the vertical movement of carbon in the Red Sea and how it fuels the metabolism of single-celled heterotrophic prokaryotes belonging to the domains Bacteria and Archaea.

The RV Thuwal was used for the field work in this study

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RED SEA SCIENCE

Researchers have shown that Benthosema pterotum or skinnycheek lanternfish are responsible for carbon transport to deep waters in the Red Sea.

“In a previous study, our co-authors Anders Røstad and Stein Kaartvedt discovered a community of fish in the Red Sea that migrate every night from around 550 meters depth to the surface waters to feed1,” says Calleja. “We wondered how this fish migration might affect the microbial community inhabiting the same depths. Our two projects sought to clarify this by collecting data from a single Red Sea sampling site.” The first study examined vertical differences in DOC concentration and the flow of carbon through microbial communities at three specific layers in the water column during the day1. Over eight days, the team monitored features such as DOC consumption, prokaryote growth and community composition in natural water samples taken from the surface, the deep layer where the fish rested during the day, and an intermediate layer at 275 meters. Bacterial growth efficiency in the deepest layer was significantly higher than previously estimated, “suggesting a labile DOC source—one that is tasty and easily broken down by the bacteria—that helps generate larger cells,” explains Calleja. Heterotrophic bacterial communities in the mesopelagic layer were also found to be more active than those in the surface waters. “Our second paper, led by a former KAUST postdoc who is now at the University of Exeter, Francisca García, followed changes over 24 hours along the whole water column, sampling 12 different depths (from 5 to 700 meters) every two hours2,” says Calleja. “We analyzed the dynamics between DOC, bacteria and fish movements during the 24-hour cycle.”

The researchers used flow cytometry to analyze microbe cell sizes and community structure at high temporal resolution, showing higher microbial diversity in the mesopelagic zone than expected. These deep microbial communities may be more dynamic than previously thought, thanks to this active carbon transfer of labile DOC by fish. “If this is happening in the Red Sea, could it be happening in other marine basins and the open ocean? It may have unprecedented implications for the global ocean carbon cycle,” notes Calleja. “These two studies are part of a wider project to determine the impact of this shortcut on global biogeochemical cycling,” adds Morán. 1. Garcia, F.C., Calleja, M.L., Al-Otaibi, N., Røstad, A., & Morán, X.A.G. Diel dynamics and coupling of heterotrophic prokaryotes and dissolved organic matter in epipelagic and mesopelagic waters of the central Red Sea. Environmental Microbiology 8, 29903000 (2018). 2. Calleja, M.L., Ansari, M.I., Røstad, A., da Silva, L.R., Kaartvedt, S. Irigoien, X. & Morán, X.A.G. The mesopelagic scattering layer: a hotspot for heterotrophic prokaryotes in the Red Sea twilight zone. Frontiers in Marine Science 5 259 (2018). MARIA CALLEJA Since joining KAUST in 2015, Maria’s work in Assoc. Professor Xose Anxelu Moran’s lab has aimed to understand the cycling and transport of organic matter in the marine environment. She is particularly interested in identifying the imprint of biological communities and processes on the chemical composition of organic compounds and how these compounds influence microbial and phytoplankton ecology.

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Sabrina Vettori (middle) and her two supervisors, Raphaël Hauser (left) and Marc Genton, discuss how their statistical method can help explain the effects of temperature and humidity on air quality.

HOW EXTREME WEATHER EXACERBATES AIR POLLUTION Simultaneously modeling air pollutants and weather under extreme conditions highlights the potential for serious health risks. Air pollution is estimated by the World Health Organization (WHO) Global Ambient Air Quality Database (update 2018) to be responsible for more than 4 million premature deaths each year due to lung cancer, acute respiratory disease and even heart disease and stroke. The threat is quickly becoming a global crisis with over 90 percent of the world’s population living in places where air pollution exposure regularly exceeds limits set by the WHO. Understanding and predicting the effects of air pollution, however, is complicated by the many varied pollutants, including ozone, particulate matter, nitrogen dioxide and sulfur dioxide, and their cumulative effects and interactions with meteorological conditions, such as temperature and humidity. To better understand such effects, Marc Genton, Raphaël Huser and Sabrina Vettori have applied their expertise in modeling spatial extremes to assess the dependence between peak exposures of multiple air pollutants and extreme weather conditions across large spatial regions.

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“There is growing interest in the health effects of interactions between high concentrations of ozone and high temperatures,” says Vettori. “Especially given the projected increasing temperature trends as a result of climate change.” The probability of multiple variables, such as pollutant concentrations or temperature, peaking simultaneously can be estimated statistically by modeling the interdependence among variables. However, classical statistical methods, which are often based on the Gaussian distribution, generally underestimate the probabilities associated with extremes. Estimation of models for extremes is also difficult due to the rarity of such events in the statistical record. “The idea behind our work was to develop intuitive statistical methods to describe the dependencies between multiple extreme phenomena collected at different spatial locations,” explains Vettori. The team propose a new class of multivariate max-stable processes, essentially a hierarchical tree structure

that is nested according to the complexity of the dependence relationships between the various spatial variables. The result is a statistical model for estimating the probability that multiple variables will reach high levels simultaneously across a wide spatial region. The study showed that ozone levels are expected to exceed safe thresholds within the next 20 years due to increasing temperatures. “This method provides a comprehensive estimate of air quality that takes into account the extremes of multiple pollutants over a large spatial region, which could be used to gauge public health risks associated with exposure,” says Vettori. “We believe it could have direct applications in multivariate data analysis for air pollution monitoring, where it could help guide policy making.” Vettori, S., Huser, R. & Genton, M. Bayesian modeling of air pollution extremes using nested multivariate max-stable processes. arxiv.org: 1804.04588 (2018).

C L IM ATE C H A NGE

CORAL TRICKS FOR ADAPTING TO OCEAN ACIDIFICATION

A molecular process that signals distress could also help corals adapt to climate change. A process that changes the regulation of genes could help corals acclimatize to the impacts of global warming. Cells commonly control gene expression by adding a methyl group to part of their DNA, changing how the information on the DNA is read without changing its genetic code. Researchers at KAUST wanted to investigate whether DNA methylation could play a role in helping corals adapt to climate change. They placed colonies of the smooth cauliflower coral, Stylophora pistillata, in seawater aquariums with varying acidity levels for two years. Ocean acidification is a consequence of climate change and hinders the ability of corals to produce the calcium carbonate skeleton they need to maintain their structures. The researchers hypothesized that DNA methylation might allow corals to mitigate these effects by changing the way they grow. After two years, the team sequenced the genomes of the corals and determined changes in methylation patterns.

“We noticed that corals grown under more acidic conditions had higher levels of DNA methylation,” says geneticist Yi Jin Liew. “Genes with increased methylation were related to cell growth and stress response, but not to calcification as we initially proposed,” he says. In line with this finding, the team discovered that cell and polyp sizes in the corals also increased with rising acidity. “The coral polyps sit in little cavities called calyxes in which they can retreat for protection,” explains molecular biologist Manuel Aranda. Larger polyps have larger calyxes. “If the calyx is bigger, the coral needs to produce less skeleton to grow at the same pace. I call this the ‘Swiss cheese hypothesis,’ where the coral makes bigger holes so it needs to make less cheese, which allows it to grow at the same speed even though skeletal production is impaired.” This trait would be advantageous in an environment where competition for space and light is an important selective pressure.

The findings indicate that DNA methylation can be used as a marker of coral stress. This epigenetic mechanism might also be harnessed to grow corals under future ocean conditions to prime them for increased temperatures before placing them on reefs, says Aranda. This process is known as environmental hardening. “We hope our contribution will change the current perception among reef biologists that epigenetics do not contribute much to coral resilience,” says Liew. The team next plans to investigate whether these epigenetic changes can be passed down to future generations. “The idea is fairly revolutionary,” says Liew. Liew, Y.J. Zoccola, D., Li, Y., Tambutté, E., Venn, A.A., Michell, C.T. Cui, G., Deutekom, E.S., Kaandorp, J.A., Voolstra, C.R., Forêt, S., Allemand, D., Tambutté, S. & Aranda, M. Epigenome-associated phenotypic acclimatization to ocean acidification in a reef-building coral. Science Advances 4, eaar8028 (2018).

Colonies of the smooth cauliflower coral, Stylophora pistillata, were placed in seawater aquariums with varying acidity levels for two years.

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REMOTE CORALS PAY THE PRICE OF CLIMATE CHANGE Corals, even in the most far-flung locations, are being affected by climate change but fare better in marine protected areas. The coral reefs of a Samoan island in the remote southwest Pacific are in a surprisingly poor condition, highlighting the far-reaching impacts of climate change. KAUST marine scientists joined colleagues on the research schooner Tara to examine the impacts of climate change on coral reefs surrounding Upolu, an island just 74 kilometers long and 24 kilometers wide, home to about 135,000 Samoans. Small island populations largely rely on healthy coral reef

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systems for their livelihoods, but the status of these reefs in remote parts of the world is poorly documented. “Investigating coral reefs in remote locations can teach us about global and local impacts on these ecosystems,” says molecular biologist Maren Ziegler. Ziegler was chief scientist on board the Tara Pacific Expedition toward the end of 2016 when researchers surveyed 124 sites over 83 kilometers of Upolu’s coastal coral reefs. “Despite the distance

from large urban centers, live coral cover was extremely low,” says Ziegler. Live coral covered less than one percent of half the sites surveyed and below 10 percent at 78 percent of the study sites on the reefs. “This means that climate change, and in particular global warming, is probably affecting coral reefs everywhere on our planet now, even around small island states in the Pacific that are only contributing a ver y small fraction of the global

greenhouse gas emissions.” Two of the reef fish species known to live in the area were 10 percent smaller off Upolu than at neighboring islands. They swam in small schools of just five fish, yet they were commonly found in schools of 20 to 60 off other Pacific islands. These observations suggest that the fish habitat is degraded and that heavy fishing is affecting the coastal ecosystem around Upolu. “Since the reefs all around the island are affected, it is likely that global factors, such as storms and global warming, which cause coral bleaching and death, are affecting the reefs around Upolu,” says Ziegler. “Local stressors, such as high loads of pollution and high fishing pressure, make it more difficult for coral reefs to

The Tara Expedition spent five days in late 2016 investigating the state of the coral reefs surrounding the southwest Pacific Samoan island of Upolu.

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withstand global stressors or to recover from them.” Two areas with 40 percent and 60 percent coral cover were found within marine protected areas established in 1999. “Local action to protect

“D e s p i t e t h e distance from large urban centers, live coral cover was extremely l o w .”

MAREN ZIEGLER POSTDOC Maren is a former postdoc from Assoc. Professor Christian Voolstra’s lab who has now moved on to a position at Justus Liebig University Giessen in Germany as a junior research group leader. Maren is interested in how changes in the environment influence the equilibrium in the coral holobiont. She combines physiological and genomic tools to untangle the interactions between host and symbionts.

“We can also study these corals to get a more detailed understanding of mechanisms of stress resilience and to assist reef restoration efforts,” he says. Even though the Red Sea coral reefs are in comparatively good condition, “we need to prepare to have the tools available to mitigate coral bleaching and to help them recover,” he says.

1,531

Total number of alumni

Employment rate

94%

*Remainder of alum are full-time students

Alumni working in-Kingdom

44%

*September 2018

Ziegler, M., Quéré, G., Ghiglione, J.-F., Iwankow, G,

Barbe, V., Boissin, E., Wincker,

local resources can go a long way,” says Ziegler. A team at KAUST’s Red Sea Research Center, led by marine scientist Christian Voolstra, is preparing to conduct a survey to identify Red Sea corals that demonstrate strong resilience to environmental pressures.

P., Planes, S. & Voolstra, C.R. Status of coral reefs of Upolu (Independent State of Samoa) in the South West Pacific and recommendations to promote resilience and recovery of coastal ecosystems. Marine Pollution Bulletin 129, 392–398 (2018).

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A degraded reef in Samoa (left) shows that even reefs far from large urban centers are being affected by climate change. However, healthy reefs (right) were found within Upolu’s marine protected areas and near the Cook Islands southwest of Samoa, indicating that local action to protect resources can go a long way.

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which absorb the sun’s rays for periods of up to two years. The westerly jet across the Atlantic Ocean becomes stronger as the atmospheric circulation adjusts to this warming. This, in turn, increases dry, cold northwesterly winds above the Red Sea: heat is lost from the sea’s waters to the

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“Unde rstandin g deep circulations is vital for Open-ocean deep convection is the main source of replenishment of the Red Sea’s deep water, while flows of water in the Gulfs of Suez and Aqaba form secondary sources.

RED SEA FLUSHES FASTER FROM FAR-FLUNG VOLCANOES

Volcanic eruptions in Mexico and the Philippines can lead to atmospheric changes that favor the ventilation of deep water in the Red Sea. Deep water in the Red Sea gets replenished much faster than previously thought and its circulation is directly affected by major climatic events, including volcanic eruptions, researchers have found. Water occupying depths from 300 to 2000 meters in the Red Sea are recognized as the warmest and saltiest deep water in the world, with near-homogenous temperatures above 20 degrees Celsius and salinities higher than 40.5 practical salinity units (psu). The world average for similar depths is 2.5 degrees Celsius and 35 psu. Until now, research has suggested that the Red Sea’s deep water is relatively stagnant, taking some 36 to 90 years to renew, and that its main source of renewal is water flowing from the northern Gulfs of Suez and Aqaba into the sea’s main basin. Associate Professor Ibrahim Hoteit, who specializes in earth fluid modeling, with Fengchao Yao, a physical oceanographer, used an ocean circulation simulator to gain further insight into the circulation of the Red Sea’s deep water.

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environm enta lly sustainable de e p - sea ex ploration an d m ining .”

air, and the surface temperature becomes cold enough to trigger warmer waters They compared the temperature and salinity to rise and colder waters to sink. This is data gathered by six cruises from along the known as open-ocean deep convection. central axis of the Red Sea and found evidence In contrast with previous studies, Hoteit revealing deep circulation changes during the and Yao found it was this open-ocean deep period between 1982 and 2011. They then convection that formed the primary source used atmospheric data to reconstruct the Red of the replenishment of the Red Sea’s deep Sea’s three-dimensional circulation over a water while the flows of water originating 20-year period. in the Gulfs of Suez and Aqaba represented “We found that the deep water of the Red secondary sources. Sea experienced rather rapid renewals Organic matter from surface waters falls in the period from 1982 to 2001, which downwards, where it decomposes into its is against the conventional idea that it is basic mineral components. This makes mostly stagnant,” says Yao. deep water rich in nutrients, making its The 1982 El Chichón volcanic eruption circulation relevant to the health of the in Mexico and the 1991 Mount Pinatubo Red Sea ecosystem as a whole. “Also, eruption in the Philippines were implicated. because the floor of the Red Sea is “The model simulation also convincingly abundant in mineral deposits and metals, linked these deep-water renewals to understanding deep circulations is vital the global climate variability associated for environmentally sustainable deep-sea with remote volcanic eruptions and the exploration and mining,” says Hoteit. North Atlantic Oscillation, an inherent atmospheric variability mostly affecting Yao, F. & Hoteit, I. Rapid Red Sea deep Europe,” Yao explained. water renewals caused by volcanic Generally, volcanic eruptions warm eruptions and the North Atlantic the middle atmosphere of the tropics by Oscillation. Science Advances 4, releasing large amounts of sulfate aerosols, eaar5637 (2018).

KEEPING UP WITH SEALEVEL RISE Maintaining a balance between rising sea levels and soil accumulation will rely on careful management of coastal regions.

Soil accumulation in coastal ecosystems could mitigate rising sea levels around the Arabian Peninsula. However, this mitigation will require efforts to preserve and restore these ecosystems. Human-driven climate change is raising sea levels around the world at increasing rates, threatening hundreds of millions of people living in coastal areas. Researchers at KAUSTâ&#x20AC;&#x2122;s Red Sea Research Center worked with colleagues at the King Fahd University of Petroleum and Minerals to determine whether this increase could be mitigated by soil accretion in coastal ecosystems. In a project supported by Saudi Aramco, they collected 52 core samples from mangroves, seagrass meadows and tidal marshes along the Red Sea and the Arabian Gulf coasts of Saudi Arabia. Using lead and carbon isotope analyses of the cores, the researchers established chronologies to estimate rates of short-term and long-term soil accumulation in these ecosystems. At the Red Sea sites, short-term soil accumulation

rates outstripped sea-level rise. However, on the Arabian Gulf coast, only mangroves accumulated soil quickly enough to counter sea-level rise, which outpaced soil accumulation at the seagrass and tidal marsh sites. In general, the long-term accumulation rates were lower but similar to the rise in sea level. Overall, the analysis indicates that soil accumulation and sea-level rise along the Saudi coast have kept pace over the long term, but recent anthropogenic shifts have made sea-level rise faster in some ecosystems. The team also measured the calcium carbonate concentration along the cores and found that soil accumulation at the sites consisted largely of carbonate accretion. These ecosystems have been called

ÂŠ 2018 VINCENT SADERNE

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A researcher collects a core sample from a seagrass meadow in the Arabian Gulf.

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Coastal ecosystems have been called blue carbon ecosystems because they can trap atmospheric carbon dioxide in the sediment.

“The sedi ment comes from outside and accumulates in these ecosystems and so serves as a carbon sink.” 20

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blue carbon ecosystems because they can trap atmospheric CO2 in the sediment. However, calcium carbonate production through calcification generates CO2, leading to a debate about whether the ecosystems act as net carbon sinks or sources. The authors believe that most of the carbonate comes from nearby coral reefs rather than local calcification. “It’s improbable that the few calcifiers in the seagrass of the Arabian Peninsula could produce so much sediment,” says Vincent Saderne, the study’s lead author. “The sediment comes from outside and accumulates in these ecosystems,” and so serves as a carbon sink. Overall, the findings highlight the importance of considering these ecosystems in planning urban and industrial development. “If we don’t stop

destroying mangroves, seafront properties will become underwater properties,” says Saderne. “Mangroves aren’t just mosquito houses; they protect the cities and the shore from sea-level rise.” Saderne, V., Cusack, M., Almahasheer, H., Serrano, O., Masqué, P., Arias-Ortiz, A. Krishnakumar, P.K., Rabaoui, L. Qurban, M.A., Duarte, C.M. Accumulation of carbonates contributes to coastal vegetated ecosystems keeping pace with sea level rise in an arid region (Arabian Peninsula). Journal of Geophysical Research 123, 14981510 (2018).

VINCENT SADERNE PH.D. STUDENT Vincent is a postdoc in Professor Carlos Duarte’s lab. Vincent is interested in studying the inorganic carbon interactions among metabolic processes of calcification, respiration and photosynthesis in benthic nearshore habitats of temperate and subtropical areas in the context global climate change and ocean acidification.

WATER BRE A K THROUGHS

WATER DESALINATION PICKS UP THE PACE

A membrane made of porous carbon-fiber structures grown on a porous ceramic substrate is more efficient than similar exisiting membranes at filtering seawater.

membranes, explains Lai. One side of the membrane is immersed in salt water while the other is in contact with freshwater, creating a gap between two liquid surfaces. “Water evaporates from the salt water and quickly passes through the carbon gap before condensing at the freshwater side. Thanks to the excellent thermal conductivity of carbon fibers, most of the energy can be recovered, which reduces energy consumption by more than 80 percent,” adds Lai. Chen, W., Chen, S., Liang, T., Zhang, Q., Fan, Z., Yin, H., Huang, K-W., Zhang, X., Lai. &

The high-flux carbon-

Sheng, P. High-flux water desalination with

Engineered porous membranes could interfacial salt sieving effect in nanoporous composite membrane desalinates seawater help recover freshwater from heavily polcarbon composite membranes. Nature with little energy luted groundwater and seawater, which is Nanotechnology 13, 345–350 (2018). consumption. of critical need in developing countries and arid environments like the Arabian Peninsula. Conventional water desalination processes rely on polymer membranes. However, if these membranes achieve very good salt rejection, they can fall short of the necessary high freshwater flux. Zhiping Lai and colleagues have developed carbon-composite membranes that consist of a network of carbon fibers deposited on a porous, hollow ceramic tube. These membranes are “the first that can be used in all three membranebased desalination processes, 1. Low-energy desalination through 2. Water evaporation at the namely membrane distillaa high-flux tubular membrane seawater-carbon fibre interface tion, reverse osmosis and forward osmosis,” says Lai. These membranes can simultaneously reject all the salt plus let large quantities of freshwater through their nanoscopic pores while consuming little energy. The water fluxes are up to 20 times higher than for commercial membranes. These results come from a unique interfacial salt siev3. Gap separating seawater 4. Nanoporous structure 5. Layered architecture ing effect, which differs from and freshwater within the of carbon- and ceramicof the carbon composite a solution-diffusion mechacarbon fibre network based membrane layers membrane wall nism observed in polymer K AUST DISCOVERY

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TorOve Leiknes (left) and Ryan Lefers consult a water-quality meter in the KAUST greenhouse, where tomatoes are being grown hydroponically.

REUSING WATER TO GROW QUALITY FOOD IN CITIES Research to optimize aquaponics systems could inform a new era of urban food production. 22

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New ways of feeding city populations are needed to cope with increasingly citycentered global populations. The availability of fresh water for agricultural use could limit traditional food production, and reliance on imported goods will be affected by rising fuel costs and environmental sustainability. TorOve Leiknes from KAUST is leading a research team in the burgeoning field of urban agricultureâ&#x20AC;&#x201D;finding ways to use city spaces to grow low-cost, high-quality organic food to provide a stable source of sustenance for city populations. For more than 20 years, Leiknes has focussed on the application of membrane technology in environmental engineering and is heavily involved in the development

WATER BRE A K THROUGHS

70% Across the world, about

In Saudi Arabia this figure is closer to

of advanced water treatment systems for sustainable water reuse. He also applies his expertise to advanced water treatment in recycling aquaculture systems: knowledge that will now feed into a new aquaponics system. Leiknes’ vision is for buildings around cities to become thriving vertical gardens, growing fresh produce, such as strawberries and salad crops, in controlled, self-sustaining conditions. His vision teams up urban agriculture with fish rearing—wastewater from fish tanks will be used to fertilize crops and vegetation will purify the water to be recycled back to the fish tanks. A new take on an ancient farming system, this aquaponics setup is

becoming popular in many cities across the world, for example in New York and Austin, Texas, where local community groups and businesses are making ingenious use of different spaces to produce food. However, providing a sustainable water source for urban agriculture, particularly in arid countries, will be the real challenge, explains Leiknes. “Across the world, about 70 percent of fresh water is used for agriculture—in Saudi Arabia this figure is closer to 80 percent,” says Ryan Lefers, agricultural engineer and part of a team led by Leiknes at KAUST’s Water Desalination and Reuse Center. “If you’re on a ship that’s sinking, you need to plug the biggest hole first. So we are

of fresh water is used for agriculture

80%

focusing our research into the viability of using wastewater for aquaponics and irrigation systems.” The team is setting up an aquaponics system at KAUST to test ways of rearing fish and growing crops using recycled residential wastewater from the university complex. Their project will investigate how to optimize the system, including trialing novel lighting methods and fish feed, and improved water-treatment processes. “A key benefit of using recycled residential wastewater is that it contains far fewer dangerous pollutants than does industrial wastewater,” explains Lefers. “However, we still need to remove any trace of potential toxins, such as pharmaceuticals, and treat the water to kill pathogens. We also need to add oxygen to the fish water, monitoring it carefully to maintain a healthy environment.” “Wastewater naturally contains valuable fertilizers that we can harness,” adds Leiknes. “We will remove ammonia from the water and use it to fertilize the plants—there’s even the possibility that fish sludge could be used for biogas production in future.” The team are using off-the-shelf equipment modified to suit their research goals, demonstrating the viability of building such aquaponics systems in the community. A key aim of their work is to optimize each part of the system separately, selectively extracting the fish waste components that are beneficial to the plants, thereby decoupling the fish rearing from the plant rearing. This will help to ensure each system is as energy efficient as possible while generating tailored water for each. They will also trial three different types of fish feed to gauge the impact of the feed on water quality. “Our results will inform future guidelines and management of aquaponics systems,”

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WATER BRE A K THROUGHS

BIO-INSPIRED MATERIALS DECREASE DRAG FOR LIQUIDS

Tiny nature-inspired cavities that trap air can stop liquids from sticking to surfaces without the need for coatings.

says Leiknes. “As you might expect, guidelines for food production are very strict, particularly when it comes to living conditions for the fish. A future challenge will be ensuring that urban planners work to incorporate urban agriculture into city legislation.” There is a bottleneck in rolling out urban agriculture in cities around the world. Many older cities do not have the infrastructure in place to support vertical gardens and aquaponics—for example, there are difficult practicalities in using city wastewater. City planners will need to ensure stringent legislation is in place if urban agriculture is to flourish, and experts in agricultural engineering and wastewater reuse will play a key role in that process. “Urban agriculture is definitely costeffective for local communities and it provides many benefits,” says Leiknes. “There are the health benefits not only from eating high-quality organic produce but also from physically working in a community garden. These schemes could provide multiple jobs, improve city environments with green spaces, and utilize run-down buildings or areas that would otherwise deteriorate. The future for aquaponics and urban agriculture is certainly looking bright, and we are proud to be adding valuable knowledge to the field.”

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An eco-friendly coating-free strategy has now been developed to make solid surfaces liquid repellent, which is crucial for the transportation of large quantities of liquids through pipes. Researchers from KAUST’s Water Desalination and Reuse Center have engineered nature-inspired surfaces that help to decrease frictional drag at the interface between liquid and pipe surface. Piping networks are ubiquitous to many industrial processes ranging from the transport of crude and refined petroleum to irrigation and water desalination. However, frictional drag at the liquid–solid interface reduces the efficiency of these networks. Conventional methods to reduce drag rely solely on chemical coatings, which generally consist of

WATER BRE A K THROUGHS

Materials could be engineered to repel liquids without coatings when carved with a bio-inspired microtexture.

perfluorinated compounds. When applied to rough surfaces, these coatings tend to trap air at the liquid– solid interface, which reduces contact between the liquid and the solid surface. Consequently this enhances the surface omniphobicity, or ability to repel both water- and oil-based liquids. “But if the coatings get damaged, then you are in trouble,” says team leader, Himanshu Mishra, noting that coatings break down under abrasive and elevated temperature conditions. So Mishra’s team developed microtextured surfaces that do not require coatings to trap air when immersed in wetting liquids by imitating the omniphobic skins of springtails, or Collembola, which are insect-like organisms found in moist soils. The researchers carved arrays of microscopic cavities with mushroom-shaped edges, called doubly reentrant (DRC), on smooth silica surfaces. “Through the DRC architecture, we could entrap air under wetting liquids for extended periods without using coatings,” says co-author Sankara Arunachalam. Unlike simple cylindrical cavities, which were filled in less than 0.1 seconds on immersion in the solvent hexadecane, the biomimetic cavities retained the trapped air beyond 10,000,000 seconds. To learn more about the long-term entrapment of

The KAUST team: Himanshu Mishra (back), Jamilya Nauruzbayeva (left) and Sankara Arunachalam. (Lead co-author, Eddy Domingues, left KAUST in 2017 for a position at the University of Aveiro.)

air, the researchers systematically compared the wetting behavior of circular, square and hexagonal DRCs. They found that circular DRCs were the best at sustaining the trapped air. The researchers also discovered that the vapor pressure of the liquids influences this entrapment. For low-vapor pressure liquids, such as hexadecane, the trapped gas was intact for months. For liquids with higher vapor pressure, such as water, capillary condensation inside the cavities disrupted long-term entrapment. Using these design principles, Mishra’s team is exploring scalable approaches to generate mushroom-shaped cavities on to inexpensive materials, such as polyethylene terephthalate, for frictional drag reduction and desalination. “This work has opened several exciting avenues for fundamental and applied research!” Mishra concludes. Domingues, E.M., Arunachalam, S., Nauruzbayeva, J., & Mishra, H. Biomimetic coating-free surfaces for longterm entrapment of air under wetting liquids, Nature Communications 9, 3606 (2018).

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ROBOTS LEARN BY CHECKING IN ON TEAM MEMBERS

Innovative drone designs and software enable a team of drones to work together in a coordinated approach. The software and hardware needed to co-ordinate a team of unmanned aerial vehicles (UAVs) that can communicate and work toward a common goal have recently been developed. “Giving UAVs more autonomy makes

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them an even more valuable resource,” says Mohamed Abdelkader, who worked on the project with his colleagues under the guidance of Jeff Shamma. “Monitoring the progress of a drone sent out on a specific task is far easier than remote-piloting

one yourself. A team of drones that can communicate among themselves provides a tool that could be used widely, for example, to improve security or capture images simultaneously over a large area.” The researchers trialed a capture-the-flag game scenario, whereby a team of defender drones worked together within a defined area to intercept an intruder drone and prevent it from reaching a specific place. To give the game more authenticity, and to check if their algorithms would work under unpredictable conditions, the intruder drone was remote-piloted by a researcher. Abdelkader and the team quickly dismissed the idea of having a central base station that the drones would communicate with. Instead, they custom-built UAVs and

SMART TECH Mohamed Abdelkader worked on a team to develop an algorithm that enables a team of unmanned aerial vehicles to work together in real time under a capturethe-flag scenario to intercept an attacker drone.

“G i v i n g UAVs more autono m y m a ke s them an even more valuable r e s o u r c e.”

incorporated a light-weight, low-power computing and wi-fi module on each one so that they could talk to each other during flight. “A centralized architecture takes significant computing power to receive and relay multiple signals, and it also has a potential single point of total failure—the base station,” explains Shamma. “Instead, we designed a distributed architecture in which the drones coordinate based on local information and peerto-peer communications.” The team’s algorithm aims to achieve an optimal level of peer-to-peer messaging— which needed to be not too much, not too little—and rapid reaction times, without too much heavy computation. This allows the algorithm to work effectively in real time while the drones are chasing an intruder. “Each of our drones makes its own plan based on a forecast of optimistic views of their teammates’ actions and pessimistic views of the opponent’s actions,” explains Abdelkader. “Since these forecasts may be inaccurate, each drone executes only a portion of its plan, and then reassesses the situation before replanning.” Their algorithm worked well in both indoor and outdoor arenas under different attack scenarios. Abdelkader hopes their software, which is now available as open-source, will provide the testbed for multiple applications. The team hope to enable the drones to work in larger, outdoor areas and to improve the software by incorporating adaptive machinelearning techniques.

(Left to right) Lab members: Kuat Telegenov (lab engineer), Fat-hy Omar Rajab (student) and Mohamed Abdelkader.

Abdelkader, M., Lu, Y., Jaleel, H. & Shamma, J. Distributed real time control of multiple UAVs in adversarial environment: algorithm and flight testing results. IEEE International Conference on Robotics and Automation (ICRA) May 21-25, 6659-6664 (2018).

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LINING MOF POCKETS TO DETECT NOXIOUS GASES Custom-made gas-sensing A porous material with tailor-made pockets stitched into its structure is a promising material for sensing noxious gases. A thin film of the material, coated onto an electrode, formed an electronic sensor that could detect traces of sulfur dioxide gas1. The sensor is a significant step toward real-world devices that can sniff out dangerous gases in real air. Although several lab-based analytical instruments can detect traces of a specific gas in the air, these instruments are typically large, expensive, power-hungry machines. There is still a need for small, inexpensive, energy-efficient sensors that, for example, could be widely deployed around industrial sites to continually monitor air quality. One promising way to make such sensors involves porous materials called metalorganic frameworks (MOFs). By making the MOF from different metal atoms and organic linkers, researchers can create materials that selectively absorb specific gases into tailor-made pockets within the

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structure. Two KAUST research groups, led by materials scientist Mohamed Eddaoudi and electrical engineer Khaled Salama, recently teamed up to develop MOF-based gas sensors. The first step was completed in 2015 when the team made a proof-of-concept sensor by coating a MOF layer onto an electrode2. The device senses gases in a similar way that a touchscreen senses a finger. The gas changes the MOF sensor’s

capacitance, an electronic property that can be directly measured using the electrode. Now, the team is working toward specific applications. “Our current work aims to identify the ideal MOF, in terms of sensitivity and selectivity, for detection of sulfur dioxide,” says Valeriya Chernikova, a Ph.D. student from Eddaoudi’s lab. The researchers selected an indiumbased version of a MOF called MFM-300 as their sensor material. A thin film of

material could lead to inexpensive devices for realtime air-quality analysis.

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“T h e s e n s o r i s a significant s t e p t owa r d r e a l- wo r l d d ev i c e s t h a t can sniff out dangerous gases i n r e a l a i r.” comprises a much more complex mixture of gases—the next step is to develop sensor arrays that pool the responses of multiple MOF materials, Chernikova says. “The data will be processed using various statistical and machine learning algorithms to improve the accuracy of the sensor’s response,” she continues. “This is commonly referred to as an ‘artificial nose’.” 1. Chernikova, V., Yassine, O., Shekhah, O., Eddaoudi, M. & Salama, K. N. Highly sensitive and selective SO2 MOF sensor: the integration of MFM-300 MOF as a sensitive layer on a capacitive interdigitated electrode. Journal of Materials Chemistry 6, 5550–5554 (2018). 2. Sapsanis, C., Omran, H., Chernikova, V., Shekhah, O., Belmabkhout, Y., Buttner, U,. Eddaoudi, M. & Salama, K.N. Insights on Capacitive Interdigitated Electrodes Coated with MOF Thin Films: Humidity and VOCs Sensing as a Case Study. Sensors 15, Sulfur-dioxide molecules (red and yellow) are selectively taken up by pores in the metalorganic framework.

the material could be grown onto the electrode under mild conditions that do not damage the sensor circuit. The resulting material forms pockets lined with two -OH groups and four C-H groups that selectively bind sulfur-dioxide molecules. In lab tests using simple mixtures of gases, the sensor could detect sulfur dioxide at concentrations of just a few parts per billion. To use the technology for real air—which

18153-18166 (2015).

VALERIYA CHERNIKOVA For this project, Valeriya Chernikova was cosupervised by Dist. Prof. Mohamed Eddaoudi and Assoc. Prof. Khaled Salama. Her research interests are focused on the synthesis and characterization of MOFs with application to membrane separation and gas sensing.

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SMART TECH

Working in a clean suit in the lab, Haiding Sun holds up a gallium oxide template.

CONTROLLING THE CRYSTAL STRUCTURE OF GALLIUM OXIDE

Precise control of the atomic structure of gallium oxide layers improves the development of highpower electronic devices. A simple method that uses hydrogen chloride can better control the crystal structure of a common semiconductor and shows promise for novel highpowered electronic applications. The electronic components used in computers and mobile devices operate at relatively low power. But high-power applications, such as controlling electrical

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power grids, require alternative materials that can cope with much higher voltages. For example, an insulating material begins to conduct electricity when the field is high enough, an effect known as electrical breakdown. For this reason, power electronics often use nitridebased semiconductors, such as gallium nitride, which have a very high breakdown field and can be epitaxially grown to create multilayered semiconductors. However, ever-increasing energy demands and the desire to make electricity distribution more efficient requires even more electrically robust materials. Gallium oxide (Ga2O3) has a theoretical breakdown field more than twice that of gallium nitride alloys and so has emerged as an exciting candidate for this function. The latest challenge however is a simple way to deposit high-quality gallium oxide on the substrates commonly used for power electronics, such as sapphire. Haiding Sun, Xiaohang Li and coworkers worked with industry partners Structured Materials Industries, Inc. in the U.S. to demonstrate a relatively simple method to control the crystal structure of gallium oxides on a sapphire substrate using a technology known as metalorganic chemical vapor deposition (MOCVD). â&#x20AC;&#x153;We were able to control the growth by changing just

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one parameter: the flow rate of hydrogen chloride in the chamber,” explains Sun. “This is the first time that hydrogen chloride has been used during oxide growth in an MOCVD reactor.” The atoms in gallium oxide can be arranged in a number of different forms known as polymorphs. β ‑Ga2O3 is the most stable polymorph but is difficult to grow on substrates of other materials. ε‑Ga2O3 has been grown on sapphire but its growth rate has been difficult to control.

K A U S T. E D U. S A

“A s i m p l e m e t h o d that uses hydrogen chloride can better control the crystal structure

S C I - C A F É I S A N I N T E R AC T I V E D I S C U S S I O N BETWEEN KAUST SCIENTISTS, COMMUNITY M E M B E R S A N D A FAC E B O O K L I V E A U D I E N C E I N A CASUAL SETTING

of a common s e m i c o n d u c t o r.” Led by Li, Sun and the team showed that they can achieve precise control of the growth rate by adding hydrogen chloride gas to triethylgallium and oxygen in their MOCVD chamber. When they added the hydrogen chloride at a low flow rate, β‑Ga2O3 formed on the sapphire substrate. But as they increased the flow rate, they were able to create ε‑Ga2O3 and even α‑Ga2O3. “We are now using kinetic models to unveil the whole mechanism of the crystallization process when hydrogen chloride is used,” says Sun, “while also working on fabricating transistors using the three phases of gallium oxide films.” KAUST have begun a close collaboration with Semiconductor Manufacturing International Corporation, an integrated-circuit foundry that provides semiconductor technology services, to fulfill its mission to pursue gallium oxide semiconductors for practical power-electronic applications. Sun, H., Li, K.-H., Torres Castanedo, C.G.,

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Okur, S., Tompa, G.S., Salagaj, T., Lopatin, S., Genovese, A. & Li, X. HCl flow-induced phase change of α -, β - and ε -Ga2O3

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films grown by MOCVD. Crystal Growth and Design 18, 2370-2376 (2018).

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3D-PRINTED CUBE DIALS INTO ENERGY HARVESTING Ambient energy emitted by

cellular phones and modems can be captured and converted into electricity using unusually shaped technology. 32

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As Internet-connected smart devices become smaller and more widespread, the challenge of powering them grows more acute. An inexpensive energy harvester developed at KAUST can help recharge Internet-of-things (IoT) gadgets using radio waves from wireless sources. O ne w ay t h at re s e arche rs are miniaturizing devices for IoT applications is through an approach called system-on-package. Recent work has shown that the protective packaging around microelectronics devices could be

used to accommodate components, such as communication antennas, for significantly reduced costs and space requirements. Atif Shamim, a professor of electrical engineering and an expert in energy harvesting, realized that system-on-package principles could help IoT devices become more self-sufficient. His team investigated strategies to build highly compact antennas that tune into the radiofrequency signals emitted from mobile and wireless devices. They then teamed up with

SMART TECH

The symmetric geometry of the cube makes it more effective at gathering energy.

Students Azamat Bakytbekov (left) and Thang Nguyen helped to develop a cube-shaped energy harvester that can gather power from a nearby smartphone.

Khaled Salama’s group at KAUST to convert this energy into electricity using semiconductor diodes. Most radiofrequency harvesters can only tap into a single part of the wireless spectrum, such as the 3G standard. Shamim’s team, however, aimed to produce a multiband device that can accumulate more energy from multiple sources of communication. “Asking one antenna to do the job of several others simultaneously is tricky,” notes Azamat Bakytbekov, the first author of the paper.

“You have to make sure the performance doesn’t drop at any one frequency point.” The researchers turned to a cubeshaped package and the mathematical concept of fractals—patterns that repeat from small to large scale—to build their harvester. First, the team 3D printed a square plastic substrate and then screen printed fractal antennas on its surface using silver metal. Finally, they glued five of the plastic pieces together with the electrical circuit to form a cube, roughly five centimeters in size.

Fractal antennas can introduce multiple resonances that allow access to broader parts of the radio spectrum. The symmetric geometry of the cube worked to enhance this effect by gathering radiation all around the cube. Subsequent wireless spectrum scanning revealed several distinct frequencies where energy harvesting could work. Experiments in real-world environments proved that the harvester could gather enough radio energy to power small wireless sensors. But the most interesting occurrence, according to co-author, Thang Nguyen, was when smartphone users passed by the 3D cube. “We saw the power gathered by the cube suddenly shoot up when a person nearby made a call,” says Nguyen. “With the increase in mobile communication, this concept enables more and more radiofrequency energy to be harvested.” Bakytbekov, A., Nguyen, T.Q., Huynh, C., Salama, K.N. & Shamim, A. Fully printed 3D cube-shaped multiband fractal rectenna for ambient RV energy harvesting. Nano Energy 53, 587–595 (2018).

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SMART TECH

SMART SKIN FOR FLEXIBLE MONITORING

An electronic tag that stretches and flexes while it records location and environmental data can monitor marine animals in their natural habitat.

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A thin smart patch called Marine Skin could make studying the behavior of marine animals easier and more informative. This system for electronic tagging of animals is based on stretchable silicone elastomers that can withstand twisting, shearing and stretching, even when exposed to high pressures in deep waters. “The integrated flexible electronics can track an animal’s movement and diving behavior and the health of the surrounding marine environment in real time,” says Joanna Nassar. Now at California Institute of Technology, Nassar was a Ph.D.

student in the KAUST team that developed the patch. Being able to monitor and record a range of environmental parameters is vital in the study of marine ecosystems. Yet existing systems for tracking animals in the sea are bulky and uncomfortable for animals to wear. “Using simple design tricks and soft materials, we were able to beat the current standard systems in terms of noninvasiveness, weight, operational lifetime and speed of operation,” says Nassar. In the current prototype, the location data is supplemented by recordings of water temperature and salinity. Additional

SMART TECH

move on to studies with dolphins and whale sharks. Their long-term aim is to achieve reliable performance when Marine Skin is attached for up to a year on individual animals of diverse types. Nassar believes that the existing system and the planned upgrades will

“The researchers hope to develop remote dataretrieval procedures by overcoming the problems of transmitting signals through w a t e r.” This carpet shark, from the order Orectolobiformes, was the first shark ever to be equipped with the marine skin.

sensing capabilities could be added in future. Possibilities include sensing the physiological state of the tagged animals. This would allow information about ocean chemistry to be correlated with the heath and activity of even small animals as they move around in their habitat. The data is currently retrieved via wireless connection when the tag is removed. In future, the researchers hope to develop remote dataretrieval procedures by overcoming the problems of transmitting signals through water. Marine Skin is one of many innovations developed by Professor

Muhammad Mustafa Hussain’s group in collaboration with Professor Carlos Duarte’s group at KAUST. “We are consistently advancing the field of flexible and stretchable electronics by making electronic systems in which every component is physically flexible,” says Hussain. His team partnered with Duarte’s group of marine scientists for their specialization in large-scale marine megafauna mobility studies. Marine Skin has been tested and demonstrated when glued onto a swimming crab, Portunus pelagicus, but is suitable for tagging a wide range of sea creatures. The team plan to

allow significantly more comprehensive analysis of the marine ecosystem, including studies of animals in locations where they could not previously be monitored. She points out that investigating behavioral changes of marine species in relation to the quality and health of the ocean will help scientists assess habitability in the context of increasing global temperatures, problems of pollution and the effects of overfishing. Nassar, J.M., Khan, S.M., Velling, S.J., Diaz-Gaxiola, A., Shaikh, S.F., Geraldi, N.R., Torres Sevilla, G.A., Duarte, C. & Hussain, M.M. Compliant lightweight non-invasive standalone “Marine Skin” tagging system, npj Flexible Electronics 2, 13 (2018).

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SMART TECH

THE RAW POWER OF HUMAN MOTION Standalone power modules that harvest and convert vibrations from their surroundings into electricity could soon fuel future microsystems.

Autonomy is a much-anticipated feature of next-generation microsystems, such as remote sensors, wearable electronic gadgets, implantable biosensors and nanorobots. KAUST researchers led by Husam Alshareef, Jr-Hau He and Khaled Salama have developed small standalone devices by integrating maintenance-free power units that produce and use their own fuel instead of relying on an external power source¹,². Triboelectric nanogenerators (TENGs) capture mechanical energy from their surroundings, such as vibrations and random motion produced by humans, and convert it into electricity. In these tiny generators, frictional contact between materials of different polarity creates oppositely charged surfaces. Repeated friction causes electrons to hop between these surfaces, resulting in electric voltage. “We exploited this triboelectric effect to harvest energy from simple movements, such as hand clapping, finger tapping and routine hand motion, to drive different types of sensors,” says Alshareef. The researchers have developed a self-powered photodetector by coupling the silicone-based polymer polydimethylsiloxane (PDMS) as a TENG with a material called an organometallic halide perovskite¹. The lead-halide-based material features optoelectronic properties that are desirable in solar cells and lightemitting diodes. To streamline their design and eliminate the need for a motion actuator, He’s team fabricated the photodetector using two multilayered polymer-based sheets

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Triboelectric nanogenerators capture mechanical energy from their surroundings.

separated by a small gap. One sheet comprised the perovskite ultrathin film while the other contained a PDMS layer. The gap allowed the team to harness the triboelectric effect when the device was activated by finger tapping. “The self-powered device showed excellent responsiveness to incident light, especially when exposed to light of low intensity,” says Mark Leung, the lead author of the photodetector study. Because of its flexible and transparent polymer components, it also retained its performance after being bent 1,000 times and regardless of the orientation of the incident light. Pushing the boundaries further, the researchers engineered a wearable self-powered bracelet that can store the converted mechanical energy by combining a carbon-fiber-embedded silicone nanogenerator with MXene microsupercapacitors². They incorporated nanogenerator and miniaturized electrochemical capacitors into a single monolithic device encased in silicone rubber. The leak-proof and stretchable shell provided a flexible and soft bracelet that fully conformed to the body. Fluctuations in the skin–silicone separation altered the charge balance between electrodes, causing the electrons to flow

back and forth across the TENG and the microsupercapacitor to charge up. In addition to exhibiting longer cycle life and short charging time, MXene microsupercapacitors can accumulate more energy in a given area than thin-film and micro-batteries, offering faster and more effective small-scale energy storage units for TENG-generated electricity. When active, the bracelet can use the stored energy to operate various electronic devices, such as watches and thermometers. “Our ultimate goal is to develop a selfpowered sensor platform for personalized health monitoring,” says Ph.D. student Qiu Jiang, the lead author of the self-charging band project. The team is now planning to introduce sensors into the system to detect biomarkers in human sweat. 1. Leung, S.-F., Ho, K.-T., Kung, P.-K., Hsiao, V.K. ., Alshareef, H.N. Wang, Z.L. & He, J-H. A self-powered and flexible organometallic halide perovskite photodetector with very high detectivity. Advanced Materials 30, 1704611 (2018). 2. Jiang, Q., Wu, C., Wang, Z., Wang, A. C., He, J.-H. Wang, Z.L. & Alshareef, H.N. MXene electrochemical microsupercapacitor integrated with triboelectric nanogenerator as a wearable self-charging power unit. Nano Energy 45, 266–272 (2018).

SMART TECH

ELECTRONIC SKIN STRETCHED TO NEW LIMITS A metal carbide within a hydrogel composite senses, stretches and heals like human skin for use in medicine and robotics.

Yizhou Zhang stretches the hydrogel.

An electrically conductive hydrogel that takes stretchability, self-healing and strain sensitivity to new limits has been developed. “Our material outperforms all previously reported hydrogels and introduces new functionalities,” says Husam Alshareef, professor of materials science and engineering. Smart materials that flex, sense and stretch like skin have many applications in which they interact with the human body. Possibilities range from biodegradable patches that help wounds heal to wearable electronics and touch-sensitive robotic devices. The material is a composite of the water-containing hydrogel and a metalcarbide compound known as MXene. As well as being able to stretch by more than 3400 percent, the material can quickly return to its original form and will adhere to many surfaces, including skin. When

cut into pieces, it can quickly mend itself upon reattachment. “The material’s differing sensitivity to stretch and compression is a breakthrough discovery that adds a new dimension to the sensing capability of hydrogels,” says first author, Yizhou Zhang, a postdoc in Alshareef ’s lab. This new dimension may be crucial in applications that sense changes in the skin and convert them into electronic signals. A thin slab of the material attached to a user’s

forehead, for example, can distinguish between different facial expressions, such as a smile or a frown. This ability could allow patients with extreme paralysis to control electronic equipment and communicate. Strips of the material attached to the throat have impressive abilities to convert speech into electronic signals. This might allow people with speech difficulties to be clearly heard. “There is real potential for our material in various biosensing and biomedical applications,” says co-author Kanghyuck Lee. More straightforward and extremely useful medical possibilities include flexible wound coverings that can release drugs to promote healing. These could be applied internally on diseased organs in addition to adhering externally to skin. The team also envisions developing a smart material that could monitor the volume and shape of an organ and vary drug release according to signals produced. An ideal potential would be to combine both medical sensing and therapy. Other exciting possibilities lie in robotics, where the material could serve in touch-sensitive fingerlike extensions for machinery, for example. There are also anticounterfeiting possibilities, with slabs of the material and integrated electronics proving highly sensitive at detecting signatures as they are written. The team have a long list of possible applications that can now be further explored and developed. “There is great potential for commercialization,” Alshareef concludes. Zhang, Y., Lee, K., Anjum, D.H., Sougrat, R., Jiang, Q. Kim, H. & Alshareef, H.N. MXenes stretch hydrogel sensor performance to new limits: hydrogels sense and heal better with MXene. Science Advances 4, eaat0098 (2018).

K AUST DISCOVERY

Signals from the electrically conductive hydrogel can clearly distinguish between different facial expressions.

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FE AT URE

PUTTI NG TH E SE NSE I N M ATE R I A L S An interdisciplinary initiative is helping KAUST be at the forefront of a digital revolution where sensors can find use just about anywhere.

FE AT URE The ability to track miniscule but important changes across a range of systems—from the body to the borough and beyond—seems limitless with the emerging array of novel devices that are tiny, self-powering and wirelessly connected. KAUST’s Sensor Initiative comprises a broad range of experts, from marine scientists to electrical engineers, who are innovating solutions to some of the most challenging obstacles in sensor technology. Together, they are powering up to transform the exciting intersection between small interconnected devices and the world around us. Capacity to monitor our surroundings also reveals new potential in environmental and community protection. For example, a sensor that can detect a flood or a fire can save lives; a sensor that can track animals could help to better manage an ecosystem; and a sensor that can read plant condition could promote sustainable farming. To take advantage of the market opportunities for sensors in both medical and environmental fields, KAUST holds an annual meeting of biologists, engineers and chemists to discuss technology development. Since 2015, these meetings have produced ambitious collaborations that aim to improve the science that underpins next-gen sensors as well as to take them to the market. Get ready to plug and play Khaled Salama, professor of electrical engineering and director of the Sensor Initiative, explains that what sets KAUST apart are the University’s human resources and outstanding lab facilities that underpin its innovative sensor technologies. With the onslaught of data coming from the hundreds of billions of sensors in our cities, cars, homes and offices, we need machine learning to help us understand the data, the supercomputing power to manage it and the expertise to make sure the machines do it all effectively. “KAUST has strength in materials research, which is where our expertise can be used for developing sensors with transducer components that can be quickly swapped out and replaced with ones customized for different biological or environmental applications,” says Salama. “Some can stick to your skin and monitor your vital signs through changes in

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your sweat while others can be placed in petroleum installations to monitor hazardous gases,” says Salama. “We’re not bound to one specific application, and each new development gives us a chance to answer some fundamental scientific questions along the way.” Say goodbye to batteries, as you know them KAUST is deploying tiny sensors across the University’s campus to model future smart cities that can continuously monitor air quality or help self-driving cars navigate. Implementing this vision means making devices that are as self-sufficient as possible. “If you have sensors containing regular batteries, they might last a thousand cycles,” says Husam Alshareef, professor of materials science. “We have to get them to last millions of times longer.” Alshareef and several international collaborators are building a technology known as microsupercapacitors—next-generation

batteries—to resolve challenges around energy storage. Through a special vacuum deposition process, the team has transformed ruthenium oxide into a thin-film electrode that can hold massive amounts of charge and quickly release it on demand. Get plant smart with winged sensors Professor Muhammad Hussain is a strong believer in the importance of availability in the sensor market. He insists that his sensors not only provide solutions to everyday problems but also that they be affordable to all. That said, he does not forgo creativity for affordability. Hussain’s plant sensors are flexible, inexpensive and range in size from 1-20 mm in diameter. When placed on a plant leaf, they can detect temperature, humidity and growth, data that can be used to help farmers farm smart—minimizing nutrient and water waste. But what makes them especially remarkable is their beautiful butterfly

FE AT URE

water to scatter the radiofrequency waves used by most sensors for geolocation. Working with the KAUST Nanofabrication Core Lab to fabricate thin-film structures, the team created flexible sensors that reveal their global position using magnetic signals that easily access subsurface environments. “Magnetic fields can penetrate many

“W h e n p l a c e d o n a p l a n t l e a f, they can detect temperature, humidity and growth, data that can be used to help farmers f a r m s m a r t .” shape. When asked why he chose the butterfly shape Hussain told us, “Butterflies are aesthetically beautiful and natural in a plant environment. Their large wings allow us to integrate many different sensors, which is especially useful for the artificial intelligence chip we are currently integrating into the system. Ultimately, we aim to create a fully interactive system such that the butterfly can deliver nutrients or gather more data.” Learn to talk effectively One of the advanced sensors being developed at KAUST is the smart bandage from the group of Atif Shamim in the electrical engineering program. This gadget uses carbon-based transducers to directly contact chronic wounds and predict signs of infection based on blood pH levels. Shamim notes that wireless communication is crucial if sensors and other components of the Internet of things are

to be integrated with everyday items. His team has pioneered the use of low-energy Bluetooth radio networks to help connect smart devices with each other and also with network servers. “Even though the Internet of things is about inanimate objects, they have to make decisions for you” says Shamim. “They need to sense and they need to communicate.” Be prepared to dive deep Shamim is partnering with other KAUST researchers, including Jürgen Kosel who specializes in using the property of magnetism in his sensor work, to track animal behavior in the Red Sea. The team created stickers—each containing a self-powered, Bluetooth-connected position sensor—that are small enough to be attached to crabs, turtles and giant clams in the Red Sea. Kosel and his group aimed to tackle the primary challenge associated with remote tracking of marine life—the tendency for

materials without affecting them, and that includes humans and other animals,” says Kosel. “We’ve shown that you can even derive how much energy a marine animal consumes using magnetic sensors that monitor water flow.” Sense the future of sensors For the Senior Vice President for Research, Jean Frechet, the possibilities are great: “With our expertise and resources, we have built bridges across disciplines by bringing together researchers from KAUST and other institutions. They inspire each other to solve challenges as diverse as the survival of marine life, communications for the 21st century, and the exploitation of big data. The KAUST Sensors Initiative will stimulate the next generation and contribute to diversifying the country’s economy as we design and engineer sensors that collect the data we need to address global challenges.”

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SENSORS HIGH AND LOW SEAFLOOR SENSOR

The various smart sensors that KAUST researchers are working on can be found all around us, from the depths of the sea to our own skin.

BUTTERFLY SENSOR

This self-contained observatory can descend up to 1000 m below sea level to collected data from the seaﬂoor. Its sensors can monitor temperature, salinity, pH and mechanical waves. The node is only 30 centimeters in diameter, and when it returns to the surface, it can communicate its location via satellite for pick up. This cost-eﬀective solution provides researchers with an understanding of sea behavior, geology and climate previously unavailable.

This butterﬂy-shaped sensor can detect the temperature, humidity and growth of plants, data that can be used to help farmers farm smart—minimizing nutrient and water waste

DATA ON PLANT CONDITION IS COLLECTED

ENVIRONMENTAL CONDITIONS ARE COLLECTED FROM ITS POSITION ON THE SEAFLOOR

PRINTED BIOSENSORS

Polymer-based glucose-detecting biosensors are inkjet printed onto paper and transferred to the skin to help diabetics regulate their sugar levels

CHANGES IN BODY CHEMISTRY ARE DETECTED FROM THE SKIN

LEAK DETECTOR SENSOR

The sensor in this clamp for oil pipe joints helps to alert engineers of leaks by detecting a change in the material properties of the 3D-printed ring that sits underneath it

DETECTS AND COMMUNICATE S LEAKS IN OIL PIPE JOINTS

SMART BANDAGE SENSOR

Inkjet-printed smart bandages that monitor bleeding, pH and external pressure can provide realtime updates on wound status using re-usable wireless technology

MAGNETIC S

This ultraﬂexible m stretched by more biocompatible, att to the human skin. it functions as a w communicates wit This could replace touch-pad technol

FE AT URE

A FLEXIBLE BATTERY SAFE FOR USE IN THE HUMAN MOUTH

GATHERS AND STORES ENERGY FROM THE ENVIRONMENT

DETECTS AND COMMUNICATES WHEN A BANDAGE NEEDS CHANGING

DENTAL BRACE SENSOR

Smart 3D-printed braces with the potential to realign teeth have biocompatible, rechargeable, ﬂexible batteries.

COMMUNICATES COMMANDS THROUGH MOTION

SKIN SENSOR

magnetic skin can be e than 100% and is taching imperceptibly . Applied to a hand, wireless controller that th a gesture pad. e present day logy.

3D CUBE SENSOR

This 3D energy-harvesting cube can convert radio-frequency energy into electricity using semiconductor diodes. Its cube shape was designed for it to gather radiation most eﬃciently from all sides.

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Burner assembly for the analysis of the interaction between flames and sound waves.

Deanna Lacoste and her student Francesco Di Sabatino discuss the advantages of the setup.

PUTTING GAS UNDER PRESSURE

Understanding the response of gas flames to acoustic perturbations at high pressure should make nextgeneration turbines safer and more efficient. Soldiers marching lockstep across a bridge can cause the structure to collapse if the rhythm of their step matches the bridge’s natural vibration frequency. Combustion engineers must consider a similar effect when designing the gas turbines used in electricity generation and aero-engines. Investigation of the flame’s response to acoustic forcing uses a parameter called flame transfer function (FTF), says Francesco Di Sabatino, a Ph.D. student under the supervision of Deanna Lacoste. The FTF is

derived from experimental measurements of the flame’s response to sound waves. But these experiments are usually run at atmospheric pressure, whereas real gas turbines reach pressures of up to 30 bar. Lacoste, Di Sabatino and their colleagues systematically investigated the effect of pressure on methane and propane gas flames. “Our experiments show that FTF at atmospheric pressure is different than FTF at elevated pressure,” says Di Sabatino. For both methane and propane gas flames, pressure had a particularly strong effect when the loudspeaker produced acoustic perturbations of 176 Hz. Just as soldiers’ feet can cause bridge sway to reach the point of destruction, a gas turbine can be damaged, or even explode, if heat and pressure fluctuations produced by the flame couple with the acoustics of the combustion chamber. At a lesser degree, this thermo-acoustic instability hampers efficient combustion, increasing noise and

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CLEANER FUELS

CH4

1 bar

2 bar

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pollution emissions. Predicting and preventing thermoacoustic instabilities remains challenging for the design of a gas turbine. To improve the models used, the team measured the stability of gas flames at elevated pressure. The size of the methane flame increased with pressure when the flame was subjected to acoustic perturbation of 176 Hz (left); for propane, the size of the flame peaked at 3 bars of pressure.

“T h e r m o acoustic instability hampers efficient c o m b u s t i o n .” The new data will assist with the design of new gas turbines, Di Sabatino says. “It will be useful for engineers to have FTFs at pressures closer to the operating pressure of gas turbines,” he says. “One next step of our research is to build a new experimental setup to reach up to 20 bar, closer to the pressures in real gas turbines,” he adds. Di Sabatino, F., Guiberti, T.F.,

THIN FILMS FOR MORE EFFICIENT SOLAR CELLS

Tantalum nitride as thin layers improves the extraction of electrons from silicon solar cells.

Boyette, W.R., Roberts, W.L., Moeck, J.P. & Lacoste, D.A. Effect of pressure on the transfer functions of premixed methane and propane swirl flames. Combustion and Flame 193, 272282 (2018).

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The efficiency of solar cells can be increased by thin-film contacts developed by researchers at KAUST. Improving the performance of solar cells requires scrutinizing every aspect of their design. First, this means improving the crystalline quality of the absorbing material to maximize the conversion of

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The team led by Stefaan De Wolf (left) and Xinbo Yang created a silicon solar cell that used an electron-selective tantalum-nitride-metal contact that improved the power conversion efficiency.

photons to negatively charged electrons and positively charged holes. Next, the device’s architecture must be optimized to ensure that these charge carriers can move efficiently through the material. Finally, the electrical contacts that extract the carriers from the device and into an external circuit need to be perfected. Xinbo Yang and his colleagues from the KAUST Solar Center and the KAUST Core Labs, together with coworkers from the Australian National University, focus on this third step by developing electron-selective tantalum-nitride thin-film contacts for silicon solar cells. The interface between a silicon and a metal contact can create a high-resistance barrier that disrupts current flow. Additionally, the metal-induced electronic states at the surface of silicon enable the

A silicon solar cell that uses an electronselective tantalumnitride-metal contact for improved efficiency.

charge carrier to recombine, which reduces the conversion efficiency. Traditionally, high-cost processes, such as diffusion and chemical-vapor deposition of additional layers were adopted to reduce the contact resistance and carrier recombination. Yang and the team combat these problems by placing tantalum nitride on silicon using a method known as atomic-layer deposition: they do this by exposing the surface to a gas, causing a high-quality thin film to build up one atom at a time. “Electron-selective tantalum-nitride contacts can simultaneously reduce the charge carrier recombination and contact resistance,” explains Yang. “This can simplify the complexity of fabricating the device and lower the production cost.” By experimentally investigating the electrical properties of the tantalum nitride–silicon interface, the researchers showed that the tantalum nitride interlayer was able to reduce the contact resistance to the flow of electrons from silicon and metal contacts made of silver or aluminum. But, it simultaneously blocked the flow of holes, reducing the carrier recombination. The team created a silicon solar cell that used an electron-selective tantalum-nitride-metal contact. They showed that this improved the power conversion efficiency—the ratio between electrical power out to optical power in—by more than 20 percent over a control device built without the tantalum nitride. They also found that it simplified the device fabrication sequence and reduced costs by eliminating doping and contact opening processes. “We are also investigating the potential application of tantalum nitride electron transport layers for organic and perovskite solar cells,” explain KAUST scientist and principal investigator, Stefaan De Wolf. Yang, X., Aydin, E., Xu, H., Kang, J., Hedhili, M., Liu, W., Wan, Y., Peng, J., Samundsett, C., Cuevas, A. & De Wolf, S. Tantalum nitride electron-selective contact for crystalline silicon solar cells. Advanced Energy Materials 8, 1800608 (2018).

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CLEANER FUELS

SIMPLE SWAP FOR A GREENER TOOLKIT

A metal catalyst that gives distinct carbon-based molecular skeletons upon ligand change may unlock cost-effective, green synthetic routes.

A nickel catalyst is set to expand the chemist’s toolkit, leading to novel key intermediates in the synthesis of natural products and pharmaceuticals. Researchers from KAUST have developed a synthetic approach that forms a carbon–carbon bond between a typically inert precursor and a boroncontaining hydrocarbon, or alkyl borane, using a nickel catalyst. Depending on the type of the ligands decorating the catalyst, this crosscoupling reaction produced alkylfunctionalized aromatic compounds. These bear chains comprising carbon and hydrogen atoms, or ketones, in which a double-bonded carbon–oxygen unit, known as the carbonyl group, is positioned between aromatic and alkyl parts. Generally, cross-coupling reactions rely on palladium catalysts to generate carbonbased molecular skeletons. Most methods have aromatic compounds containing a halide, such as iodide or bromide, that are paired with aromatic boranes to build asymmetric molecules. However, these halide-based methods produce corrosive waste. A green alternative to halides are naturally abundant carbonyl-based compounds called esters but these are inactive in palladium-catalyzed crosscoupling reactions that involve elimination of carbon monoxide. To solve this issue, the team led by Magnus Rueping and Luigi Cavallo created a nickel catalyst that activates the crosscoupling of aromatic esters and alkyl boranes. In this reaction, the ester provides the aromatic portion of the product with or without a carbonyl group, while the borane is the alkyl precursor.

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A bidentate ligand (orange and grey) on the nickel atom (blue) promotes the elimination of carbonyl in the ester (green and red) in this transition state.

The researchers demonstrated that the reaction yielded a different family of products when they switched from one type of phosphorus ligand to another. Specifically, in the presence of a monodentate ligand, which is attached to the nickel center by a single bond, the reaction gave ketone derivatives. In contrast, ligands that formed two bonds with the metal promoted the production of alkyl arenes. “These experimental results were not easy to explain,” says Rueping. “Therefore, we used computational studies to help us understand the molecular mechanism and reaction pathway.” This tunable approach was found to apply to a wide range of boranes and esters, such as benzene-like and heteroatomcontaining aromatic derivatives. It generated essential intermediates in natural-product synthesis, such as

potential next-generation antidepressants, and a potent antagonist for important cell adhesion proteins known as integrins. “These results were exciting as most researchers would not have expected that this unusual site-selective reaction could be achieved by simply changing the ligands of the metal complex,” says Rueping. His team is currently studying other metal catalysts to simplify the synthesis of natural products and functional molecules. Chatupheeraphat, A., Liao, H.-H., Srimontree, W., Guo, L., Minenkov, Y., Poater, A., Cavallo, L. & Rueping, M. Ligand-controlled chemoselective C(acyl)-O bond vs C(aryl)-C bond activation of aromatic esters in nickel catalyzed C(sp2)-C(sp3) cross-couplings. Journal of the American Chemical Society 140, 3724–3735 (2018).

CLEANER FUELS

(From l-r) Efstathios Tingas and Wonsik Song discuss the results of the study with their supervisor, Hong Im.

SOLAR FUELS WORKING WELL UNDER PRESSURE

Computer analysis aids the formulation of methanol-based renewable fuels that can operate under compression ignition conditions. Highly fuel-efficient new engine designs could significantly reduce the environmental impact of vehicles, especially if the engines run on renewable, nonpetroleumbased fuels. Ensuring these unconventional fuels are compatible with next-generation

engines was the aim of a new computational study on fuel ignition behavior. Led by Hong Im, the team investigated the ignition of methanol-based fuel formulations. “Methanol is considered a promising fuel from both economic and environmental

standpoints,” says Wonsik Song, a Ph.D. student in Im’s team. Methanol can be produced renewably as a biofuel or by a solar-driven electrochemical reaction that makes methanol from carbon dioxide. However, pure methanol fuel is ill-suited to the latest engine designs. Conventional gasoline engines use a spark to ignite the fuel. Some modern gasoline engines can switch to compression-ignition mode, operating like a diesel engine under certain conditions to maximize fuel efficiency. But methanol is not reactive enough for compression ignition, says Song. “Our approach is to blend a more reactive fuel, dimethyl ether (DME), with methanol to make a fuel blend that is usable in compression-ignition engines and provides better

combustion efficiency than the spark-ignition counterpart.” The team used computational analysis to investigate methanol-DME combustion chemistry. Because combustion is too complex to efficiently simulate in full, the researchers first generated a skeletal model of the process in which peripheral reactions were stripped away. “Starting from the detailed model, including 253 chemical species and 1542 reactions, we generated a skeletal model comprising 43 species and 168 reactions that accurately describe the ignition and combustion characteristics of methanol and DME,” explains Efstathios Tingas, a postdoctoral member of Im’s team. The researchers showed that DME dominated reaction pathways during the initial

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CLEANER FUELS

Plots of the temperature profiles in the mixture fraction space during the ignition event for (a) DME0 and (b) DME50.

phase of ignition and was a highly effective ignition promoter. They also examined the effect of increasing the initial air temperature to simulate the hot spots that might develop inside the engine. “At high temperatures, DME actually retards ignition slightly because DME chemistry relies on the formation of some highly oxygenated molecules, which are inherently unstable at higher temperatures,” Tingas says. However, at high temperatures, the methanol itself becomes highly reactive. They also studied DME’s effects on ignition timing. “This study serves as a basic guideline to study the ignition of methanol and DME blends in combustion engines with compression ignition modes,” says Song. The next step will be to perform more complex simulations that incorporate the effects of turbulence on fuel ignition, he adds. Song, W., Tingas, E.-A. & Im, H.G. A computational analysis of methanol autoignition enhancement by dimethyl ether addition in a counterflow mixing layer. Combustion and Flame 194, 84-98 (2018).

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BASKING IN A QUANTUM EFFICIENCY GLOW Printable solar materials could soon turn many parts of a house into solar panels. New houses could soon deliver on a long-awaited promise and incorporate windows or roof tiles that harvest solar energy, research conducted at KAUST suggests. Derya Baran, at the KAUST Solar Center, and her colleagues have developed a photovoltaic organic material that captures light efficiently and that potentially could be

coated on building materials. Traditional roof-mounted solar panels are made from slabs of silicon, but organic molecules can also capture energy from sunlight. These molecules could be formulated as inexpensive printable inks that are applied to regular building components such as windows. Turning sunlight into electricity is a multistep

CLEANER FUELS known as EHIDTBR, assessed by Baran and her colleagues offers several advantages: The team showed that as well as strongly absorbing visible light, it mixed well with the electron donor component, which is important for long-term stability and performance. EHIDTBR was also very efficient at dissociating excitons and preventing recombination—a property that should make for easy manufacturing, Baran says. In materials where recombination is high, the lightharvesting layer must be very thin so that the charges quickly reach the electrode layer, minimizing their chance to recombine. But these ultrathin layers are challenging to manufacture. “Thicker films are easier to print, particularly when they need to be scaled up for manufacturing,” Baran says. Scaling up the technology is the team’s next step, Baran adds. “We have a spin-out company from KAUST Solar Center and through this company we want to make photovoltaic windows for electricity generation.” Baran D., Gasparini, N., Wadsworth, A., Tan, C.H., Wehbe, N., Song, X., Hamid, Z., Zhang, W., Neophytou, M., Kirchartz, T., Brabec, C.J., Durrant, J.R. & McCulloch, I. Robust nonfullerene solar cells Derya Baran investigates the reliability of organic solar cells under light and thermal stress.

approaching unity external quantum efficiency enabled by suppression of geminate recombination. Nature Communications 9, 2059 (2018).

process, and the key to developing high-performance organic photovoltaic materials has been to find organic molecules that are good at every step, Baran explains. When light strikes an organic photovoltaic material, it knocks an electron free, leaving behind a positively charged hole. If the oppositely charged electron and hole recombine, the captured energy is lost. Thus, organic solar cells incorporate a mixture of electron donor and electron acceptor molecules to draw the charges apart.

“When I started my postgraduate studies in 2015, there was a lot of hype about fullerene buckyball derivatives as acceptors, and record efficiencies were around 10-11 percent with poor stabilities,” Baran recalls. But fullerenes have several drawbacks—not least, relatively poor light absorption—so Baran has been investigating nonfullerene acceptors. “Now efficiencies up to 17 percent are being reported,” she says. “I believe these acceptors will shape the future of organic photovoltaics.” The nonfullerene acceptor,

Organic solar cell devices are tested by evaluating their degradation in response to exposure to different types of light.

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CLEANER FUELS

A new conceptual model for describing a fuel’s composition can accelerate and simplify combustion simulations. The gasoline and diesel we pump into our vehicles is a complex cocktail that can contain thousands of different chemicals. But look closer at the fuel, and the overwhelming complexity starts to resolve itself. Rather than try to model fuel combustion based on the long list of molecules the fuel contains, KAUST researchers found a shorthand: they now show that they can distill the complexity into a very short list of molecular subunits or functional groups most fuel molecules are made from. This radically simplified method for accurately simulating fuel combustion was developed by Ph.D. student Abdul Gani Abdul Jameel with Mani Sarathy and team. The project began with the hypothesis that the combustion behavior of each component of a fuel is dictated by the functional groups it comprises. To corroborate the theory, the team performed high-resolution nuclear magnetic resonance analysis in KAUST’s Core Labs to identify the main functional groups in a series of complex fuels. They then made simple surrogates for each fuel by selecting one or two molecules that contained the functional groups in the

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same balance as the real fuel. Comparing key combustion parameters, such as ignition delay time and smoke point in the lab, the researchers confirmed the simple surrogates were faithful mimics of the real fuel. They showed a good surrogate needed to match the average molecular weight and contain the right proportions of just five key carbon-hydrogen functional groups: CH3, paraffinic CH2, paraffinic CH, naphthenic CH–CH2 and aromatic C–CH. Traditional combustion modeling accurately captures the behavior of fuel mixtures by adding detailed chemical kinetics data for increasingly more of the components in the fuel, but the drawback is that the simulation becomes prohibitively slow to run. “We have shown that adding complexity to models is not necessary, as long as underlying features of simpler molecular parameters, the functional groups, are captured,” Sarathy says. The team’s method for making simple fuel surrogates will directly improve the design of efficient new engines, explains Abdul Jameel. “Using a minimal number of components significantly reduces the time

involved in developing chemical kinetic models and the computational expenses involved in simulating combustion in internal combustion engines,” he says. But the team’s functional-group-based approach will reach far beyond surrogate formulation. “We are currently developing machine-learning-based models to predict the combustion properties of fuels based on their functional groups,” Abdul Jameel adds. Abdul Jameel, A. G., Nasera, N., Issayeva, G., Touitoub, J., Ghosh, M.K., Emwas, A-H., Farooq, A., Doley, S. & Sarathy, S. M. A minimalist functional group (MFG) approach for surrogate fuel formulation. Combustion and Flame 192, 250-271 (2018).

ABDUL JAMEEL Abdul is a Ph.D. candidate under Assoc. Professor Mani Sarathy in the Clean Combustion Research Center. He is interested in combustion modeling for higher efficiency combustion. Abdul earned his Bachelors and Masters degrees from Anna University in India.

INNOVATI V E BIOTEC H

DNA fragments. Zaher was surprised to discover that FEN1 acted as a switch between two different enzyme pathways. If the flap was short, FEN1 docked to the DNA to let the Okazaki fragments join. However, if the flap was long, FEN1 bounced off, leaving two other enzymes called Dna2 and RPA to dock on and cut the bulk of the flap before FEN1 in turn came in to finish the job.

“F E N 1 a c t e d as a switch First author Manal Zaher discovered that the enzyme FEN1 acts as a switch during DNA replication.

THE LONG AND SHORT OF DNA REPLICATION An unexpected two-step mechanism occurs when cells copy DNA. The process of copying DNA is complex choreography that requires rapid speeds and pinpoint precision. Discovering the intricate details of this process could identify new ways to target diseases, such as cancer, and KAUST scientists have just uncovered a crucial step. The DNA in each human cell is around 3 billion digits long and has to be copied every time a cell divides— which occurs nearly 2 trillion times each day. If errors occur in DNA replication, cells can become abnormal and give rise to disease. DNA code that has mutated to allow the cell to divide uncontrollably, for instance, can lead to cancer. This makes it crucial to understand how enzymes replicate

and repair DNA, says Manal Zaher, Ph.D. student in Samir Hamdan’s group at KAUST and first author of the study. Zaher investigated the enzymes that allow short DNA strands formed during DNA replication, called Okazaki fragments, to link up into a continuous string of DNA. By a process known as Okazaki fragment maturation, an enzyme called FEN1 cuts off “flaps” in the Okazaki fragments that need to be removed

before the fragments can join up. “Sequence-based specificity partially explains the secret of replication fidelity; however, we lack key information about the basis for the structure-based excision by FEN1 required at ~50 million Okazaki fragment sites during human DNA replication,” Hamdan explains. FEN1 is overproduced or altered in many forms of cancer, and Zaher wanted to investigate the exact involvement of this enzyme. The researchers used an imaging technique called The DNA in each human cell is single-molecule around FRET to discover 3 BILLION digits long how FEN1 docks and is released from other enzymes and

between two differ ent enzyme p a t h w a y s .” “This two-step mechanism could significantly help our understanding of the regulation of the subsequent Okazaki fragment steps,” explains Zaher, “and it is important particularly because mutations in both Dna2 and RPA have also been linked to cancer.” Hamdan’s group has set its sights on investigating the next interaction that FEN1 undergoes, continuing to unravel the mysteries of DNA replication one step at a time. Zaher, M. S., Rashid, F., Song, B., Joudeh, L. I., Sobhy, M. A., Tehseen, M., Hingorani, M.M. & Hamdan, S.M. Missed cleavage opportunities by FEN1 lead to Okazaki fragment maturation via the long-flap pathway. Nucleic Acids Research 6, 29562974 (2018).

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THE DYNAMIC MOLECULAR CHANGES OF HOMING Molecules re-organize to slow stem cells down, giving them a

The initial tethering and rolling step of stem cell homing is mediated by molecules, including E-selectin, on the inner surface of blood vessels and CD44 on the surface of stem cells.

A new microscopic technique allows researchers to observe the initial nanoscale changes that are part of the complex process of transplanted stem cells homing in on, and specifically settling in, the bone marrow. Understanding the details of this process can improve the success of stem cell transplantations for treating leukemia. Microscopist Satoshi Habuchi and colleagues developed their microfluidics-based super-resolution microscopy platform to improve the ability of researchers to visualize the dynamic nanoscale changes that happen to stem cells as they move in blood. Current techniques only enable researchers to identify the molecules involved in stem cell homing—a phenomenon that allows cells to migrate to their organ of origin—but not what is happening at the nanoscale or over time. For homing to succeed, stem cells moving along in a flowing circulation need to be able to slow down, attach to the inner lining of the blood vessel (called the endothelium), and then migrate across this lining into the bone marrow.

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“U n d e r s t a n d i n g the molecular process will directly contribute to increasing homing e f f i c i e n c y.” This process is important for treating leukemia patients: injected stem cells that migrate to the bone marrow can make new, healthy blood cells after the cancerous leukemic cells are destroyed by chemotherapy. However, stem cell homing in these transplantations

is often inefficient and thus requires large numbers of stem cells to improve their chances of reaching the bone marrow. “Understanding the molecular process will directly contribute to increasing homing efficiency and will eventually contribute to the success of leukemia treatment,” explains KAUST alumna Karmen AbuZineh, first author of the study. Habuchi and his team’s approach involves fixing the stem cells as they roll and interact with endothelium molecules that are immobilized at the bottom of the team’s microfluidic chamber. The molecules are tagged with fluorescent antibodies so they can be visualized under a super-resolution fluorescent microscope. The approach showed that, as stem cells move through blood vessels, CD44 molecules, located on protrusions extending from their membranes, reorganize themselves with the help of the cytoskeletal structural protein actin and fatty-acid chains of lipids. This reorganization helps the stem cells bind strongly to a molecule called E-selectin on the inner lining of blood vessels, slowing them down so they can roll over the vessel endothelium and eventually bind to it. “Our new method revealed that the molecular dynamics of hematopoietic stem-cell homing are far more complicated than previously thought,” explains AbuZineh. “Our study yielded more questions than answers,” she says, and reveals details about the initial step of homing. “This is just the beginning.” The team will now apply their technique to investigate the subsequent steps involved in homing. AbuZineh, K., Joudeh, L. I., Al Alwan, B., Hamdan, S. M., Merzaban, J. S., & Habuchi, S. Microfluidics-based superresolution microscopy enables nanoscopic characterization of blood stem-cell rolling. Science Advances 4, eeat5304 (2018).

chance to adhere to and eventually cross the inner lining of blood vessels into the bone marrow.

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DETECTING METABOLITES AT CLOSE RANGE Pairing a conjugated polymer with a redox enzyme generates a fast, selective and sensitive electrochemical biosensor for metabolites.

Sahika Inalâ&#x20AC;&#x2122;s team is working on a biosensor design that will detect metabolites in different environments. (l-r): AnnaMaria Pappa, Achilleas Savva, Sahika Inal and David Ohayon.

A novel concept for a biosensor of the metabolite known as lactate combines an electron transporting polymer with lactate oxidase, which is the enzyme that specifically catalyzes the oxidation of lactate. Lactate is associated with critical medical conditions so its detection is important for healthcare.

Biosensor performance hinges on electron transfer between sensing electrode and enzyme: this increases when there is a decrease in the distance between enzyme active sites and the electrode surface. Redox enzymes have emerged as optimal components for biosensors because their ability to realize electron transfer complements their specificity in target binding and catalytic activity. Typical efforts to achieve good electrical communication involve convoluted electrode modifications and additional mediators, which are redox-active molecules

that shuttle electrons between electrode and enzyme. Therefore, biosensors to date have been limited in terms of their target metabolites and environments. This has hampered their use for applications across diverse fields, such as biotechnology, agriculture and biomedicine. Instead, their main use has been restricted to in vitro electrochemical biosensors for glucose monitoring in diabetes patients. To fill this gap, Sahika Inal from KAUST and collaborators from Imperial College London and the University of Cambridge, U.K., have developed a biosensor that can be adapted in a micronscale transistor configuration to detect any metabolite of interest.

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side chains that facilitate intramolecular interactions with lactate oxidase, bringing the enzyme close to the transducing material. This promotes electrical communication and, consequently, enhances the polymer’s sensitivity toward lactate. These polymer–enzyme interactions also avoid modification to the electrode surface and prevent use of a mediator, “which simplifies device fabrication,” explains Inal. She adds that, unlike previous biosensors, the device does not require a reference electrode, which provides design flexibility. Pappa, A. M., Ohayon, D., Giovannitti, A., Maria, I. P., Savva, A., Uguz, I., Rivnay, J., McCulloch, I., Owens, R.M. & Inal, S. Direct metabolite detection KAUST researchers have developed a biosensor that can be adapted in a micron-scale transistor configuration to detect any metabolite of interest.

At the heart of the proof-of-concept device, the researchers have conjugated lactate oxidase with a so-called organic electrochemical transistor polymer. This electron transporting polymer simultaneously acts as an efficient switch and a powerful signal amplifier: it can accept electrons from the enzymatic reaction and undergo multiple reduction reactions through several redox-active sites. This polymer also bears hydrophilic

“T h e d e v i c e d o e s not require a reference electrode, which provides design f l e x i b i l i t y.”

with an n-type accumulation mode organic electrochemical transistor. Science Advances 4, eaat0911 (2018).

SAHIKA INAL Sahika’s research interests lie at the intersection between biology and electronics—bioelectronics. She works with organic electronic materials and devices that can address research and clinical health monitoring and therapy needs.

1,054 students registered from 74 countries * Fall 2018

Apply today: kaust.edu.sa

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ENZYME ADOPTS DYNAMIC STRUCTURE TO FUNCTION IN HOT, SALTY SEA

Protein analysis could lead to new advances in DNA sequencing technologies. For the microbes that dwell in the hot, salty depths of the Red Sea, life is a delicate evolutionary balancing act. Just for these critters to replicate their DNA requires an enzyme that’s adapted to both high temperatures and high salt concentrations, two environmental factors that impose countervailing selective pressures on the structure of a protein. A KAUST team has now characterized and engineered a DNA-synthesizing enzyme from a deep-sea microbe that seems to split the difference, being just rigid enough for thermal adaptation, but flexible enough to deal with salt-induced structural changes. The findings reveal how evolution can fine-tune proteins to be ideally suited for life in extreme environments. Moreover, they could have practical applications for biotechnology and biomedical research. “These properties are appealing for nextgeneration DNA sequencing techniques,” says KAUST professor Samir Hamdan who supervised the study. “It’s absolutely worth putting a significant effort now into exploring the biotechnology potential of DNA-processing enzymes from these microorganisms.” Hamdan and his lab collaborated with faculty members from other KAUST groups—including the Red Sea Research Center and the Computational Bioscience Research Center—and across biological and physical sciences divisions to study a DNAsynthesizing polymerase enzyme from a single-celled microbe found living off the coast of Saudi Arabia in a brine pool that was four-times saltier and 16-times hotter than average sea water. “This polymerase,”

says the study’s lead author, Masateru Takahashi, a researcher in Hamdan’s lab, “is the most salt-tolerant polymerase that is also thermally stable.” The researchers modeled the structure of the enzyme from its protein sequence and conducted biochemical and structural analyses to interrogate its physical configuration. They identified many interactions between oppositely charged regions of the protein that gave the

enzyme shape. However, the abundance of excess negatively charged regions also helped push apart the enzyme to some degree, giving it the structural dynamism to deal with increased salt concentrations. That flexibility—and subsequent salt-induced rigidity—could also explain why this polymerase enzyme has a unique ability to use zinc ions as helper molecules, unlike most other DNAsynthesizing enzymes of its kind. With these insights, the team created a salt-tolerant hybrid version of a polymerase that many biologists are already using to amplify DNA for their experiments. The insights gleaned from these engineered enzymes, says Takahashi, could lead to new reagents and methods for the biotechnology industry. Takahashi, M., Takahashi, E., Joudeh, L.I., Marini, M., Das, G., Elshenawy, M.M., Akal, A., Sakashita, K., Alam, I., Tehseen, M., Sobhy, M., Stingl, U., Merzaban, J.S., DiFabrizio, E. & Hamdan, S. Dynamic structure mediates halophilic adaptation of a DNA polymerase from the deep-sea brines of the Red Sea. The FASEB Journal 6, 3346-3360 (2018).

Lead author Masateru Takahashi modeled the structure of the enzyme from its protein sequence and conducted biochemical and structural analyses to interrogate its physical configuration.

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MINING RED SEA BACTERIA FOR INDUSTRIAL POTENTIAL

cluster in strains of the B. paralicheniformis species, in this case B. paralicheniformis Bac48, called trans-acyltransferase nonribosomal peptide synthetase/polyketide synthase, which is associated with the production of a specific group of compounds. “The findings affirm the premise that the Red Sea is a metabolically unique environment worthy of exploration for

“T h e f i n d i n g s a f f i r m

Genome sequencing of two Red Sea bacteria highlights their potential as industrial workhorses.

the premise that the Red Sea is a metabolically unique environment worthy of exploration for efficient m i c r o b e s .” efficient microbes that can be used as biotechnological hosts,” says computational bioscientist Ghofran Othoum, the first author of the study. “Also, our computational exploratory approach showed the strength of computer modeling methods in applications that require ranking biological systems for biotechnological use.” Future research will focus on seeking out which bioactive compounds are produced by the two Red Sea strains.

Similarity between the genomes of Bac48 and Bac84. Developed using data visualisation software, this figure shows synteny blocks between B. paralicheniformis Bac48 and B. paralicheniformis Bac84. Regions I, II and III are regions in B. paralicheniformis Bac48 that are missing in B. paralicheniformis Bac84.

Othoum, G., Bougouffa, S., Razali, R., Bokhari, A., Alamoudi, S., Autunes, A., Xao.,

Analyses of two bacterial strains from the Red Sea show they are enriched with gene clusters with potential to activate the synthesis of a wide range of industrially useful compounds, from novel antibiotics, anticancer agents and pigments to those useful for crop protection and the food industry. Bacteria are a rich resource for bioactive chemical compounds and Magbubah Essack, of KAUST’s Computational Bioscience Research Center, explains that bacterial strains able to withstand the Red Sea’s highly saline, warm waters were anticipated to produce sturdy enzymes suited for industrial applications.

The team sequenced the genomes of two Bacillus species: B. paralicheniformis Bac48 collected from mangrove mud and B. paralicheniformis Bac84 collected from a microbial mat in the Rabigh Harbor Lagoon on Saudi Arabia’s west coast. These two were compared with the documented genomes of three other B. paralicheniformis and nine B. licheniformis strains. The Red Sea strains had a higher number of gene clusters associated with bioactive compound synthesis compared to the other Bacillus strains. The team also report the first use of a computer program to identify a gene

G., Hoehndorf, R., Arold, S.T., Gojobori, T., Hirt, H., Mijakovic, I., Bajic, V.B. Lafi., F.F. & Essack, M. In silico exploration of Red Sea Bacillus genomes for natural product biosynthetic gene clusters. BMC Genomics 19, 382 (2018).

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Bacteria are a rich resource for

BIOACTIVE chemical compounds

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SOLVING REAL-WORLD PROBLEMS

The INLA approach represents a different way of analyzing highdimensional datasets containing thousands of measurements—such A tool developed by Håvard Rue has as those used for modeling climate or transformed data analysis, interpretation predicting weather models—and are and communication. It has been applied too complex for methods like Markov chain Monte Carlo sampling, which broadly: from modeling the spread of are time-consuming and impractical infectious diseases to mapping fish stocks. for very large models. To help apply the INLA statistical method and to better analyze Statistics is the science of learning from data, increasingly large datasets, Rue and his colleagues with statisticians providing valuable insights into developed the R-INLA statistical software package, the most pressing problems facing humanity, such which enables INLA application in diverse fields, as the health impacts of pollution to the spread of from healthcare to ecology. infectious diseases. For example, Gavin Shaddick, professor of Data SciResearchers need to understand statistics if they are ence and Statistics at the University of Exeter in the to make informed decisions. United Kingdom, used R-INLA to analyze a database “Providing the tools for scientists to better undercontaining data from more than 4,300 cities in 100stand real-world problems means policymakers have plus countries to model the health and environmental impacts from air pollution. access to reliable data for making important deci“Air pollution is a major risk factor for global health sions that affect many aspects of life, from health and with 4.2 million deaths annually attributed to fine the environment to the economy and social issues,” particulate matter pollution,” says Shaddick. “Withexplains Professor of Statistics Håvard Rue. out R-INLA we would not have been able to perform Rue is a pioneer in the field of computational Bayesthese analyses on a global scale.” ian statistics, a method that applies probabilities to The work, in collaboration with the World Health statistical problems, leading to faster and more accuOrganization (WHO), has shown that 92 percent of rate predictions. His work focuses on the application the world’s population resides in areas exceeding the of integrated nested Laplace approximations (INLA), WHO’s air quality guidelines. an approach for undertaking Bayesian inference that The method has also been used by the Malaria Atlas updates conclusions that are drawn from statistical models in the light of new data. Project (MAP), which disseminates free, accurate, up“The main issues with Bayesian modeling are speed to-date information on malaria, and aims to limit the and accuracy,” explains Rue. “Normally you have to spread of the disease. According to the WHO’s World trade speed for accuracy, but with INLA you get both. Malaria Report 2017, an estimated 216 million cases It’s almost too good to be true.” of malaria occurred globally in 2016, an increase of

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This map shows that 92 percent of the world’s population resides in areas exceeding the WHO’s air quality guidelines.

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around 5 million cases from the previous year. “Before R-INLA if was not possible to perform inference for more than a thousand observations, making this an important tool in understanding the spread of malaria,” says, Samir Bhatt from Imperial College Public School of Health in London, U.K., who used the R-INLA to model the prevalence of different forms of malaria on a global scale. The Center for Disease Control and Prevention (CDC) is also using R-INLA to map the rising numbers of suicides across the United States, providing an unprecedented level of detail by allowing changes in suicide rates in over 3,000 counties to be tracked from 2005 to 2015. “Understanding the geographic patterns of suicide rates helps us to determine which counties report high rates and are in need of suicide prevention resources,” explains Diba Khan, senior service fellow at the CDC. “By using INLA, local public health agencies are able to allocate funds to achieve health outcomes not possible from only state-level data.” The INLA method has also been applied by researchers at the Catholic University of Valparaíso to map the distribution patterns of shrimp off the coast

of Chile. It has allowed them to identify areas where fishing is possible and to make recommendations on catch quotas to help manage fish resources. “I’m still surprised when I see applications of INLA in areas I have never heard of and are outside core statistics. This demonstrates that what we are doing is important and has an impact on how people work with statistics,” says Rue. 1. Rue, H., Riebler, A., Sørbye, S.H., Illina, J.B. & Simpson, D.P. Bayesian computing with INLA: A Review. Annual Review Statistics Applications 4, 395421 (2017). 2. Bakka, H., Rue, H., Fuglstad, G-A., Riebler, A., Bolin, D. et al. Spatial modeling with R-INLA: A review. WIREs Computational Statistics 10, (2018).

HÅVARD RUE Originally from Norway, Håvard joined the Statistics program at KAUST in January 2017. His research interests lie in computational Bayesian statistics and Bayesian methodology. As described by this story, his main body of research is the R-INLA project.

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SCANNING IN THE FOURTH DIMENSION

A novel imaging method makes it possible to capture object deformation in three dimensions over time with unprecedented accuracy. Three-dimensional (3D) computed tomography is a widely used technology that visualizes an object’s external and internal structure by assembling a series of two-dimensional images taken sequentially across or around it. However, as anyone who has had a medical magnetic resonance imaging scan will recall, this type of 3D reconstruction requires the subject to be motionless throughout the capture process, which can take minutes. Capturing a 3D structure that changes or deforms over time is much more difficult, and existing approaches often yield reconstructions marred by image artifacts and 62

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partial surfaces. Guangming Zang, Ramzi Idoughi and their colleagues, under the leadership of Wolfgang Heidrich, have developed a novel four-dimensional imaging method that vastly improves the quality of such space-time tomography for rapidly deforming objects. “The primary challenge is when the deformation is so fast that the scanner can only capture a few images before the deformation becomes significant,” explains Zang. “The problem is then to reconstruct highly detailed 3D objects given only a few projections with a lot less information than would be available when reconstructing static objects.” The team tackled the challenge in two parts. First, they modified the capture sequence to have a better

The deformation of the object over time can then be reconstructed with high fidelity. This method was used to capture a wide range of dynamic phenomena, such as dehydration and rehydration of organic objects, rising dough and fluid flows.

ALL FIGURES WERE REPRODUCED FROM REFERENCE 1

The above projection shows the rehydration of a dried mushroom under a melting ice cube directly before and after scanning.

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1 0

4 5

Round 1

Round 2

ATTEMPTING TO TAME PLASMAS IN FUSION A numerical study reveals how

Round 3

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to reduce instabilities in the complex flow of plasma. Round 3

Round 4

A 360-degree scan is completed using each round offset to enhance information capture.

distribution of scans over time. Then, they created an algorithm that allows the reconstruction at a given time point by using information from previous and subsequent acquisition steps.

“T h e t e a m h a s developed a novel fourdimensional imaging m e t h o d .” “This is a major step toward making 3D tomography useful for probing internal structures of objects when changes during scanning cannot be avoided,” says Zang. Zang, G., Idoughi, R., Tao, R., Lubineau, G., Wonka, P., Heidrich, W. Space-time tomography for continuously deforming objects. ACM Transactions on Graphics 37, Article 100 (2018).

Nuclear fusion, the release of energy when light atomic nuclei merge, is touted as a carbon-free solution to global energy requirements. One potential route to nuclear fusion is inertial confinement. Now a KAUST-led team has modeled the complex flow of plasma that could occur in such a fusion reactor. Inertial confinement involves firing multiple powerful laser beams at a hydrogen pellet from many directions, which causes an implosion shockwave that heats the target to temperatures high enough to create a plasma—a cloud of charged particles—and initiate fusion. The pellet should implode symmetrically, but slight differences in the power of the laser beams creates plasma of differing temperature and density, which flow differently and create instabilities in the fuel. Ph.D. student Yuan Li and his supervisor Ravi Samtaney from KAUST’s Mechanical Engineering program and Vincent Wheatley from The University of Queensland, Australia, used a fluid model of plasma dynamics to investigate the evolution of a particular type of instability called the Richtmyer–Meshkov instability (RMI). The RMI starts as small perturbations between regions of impulsively accelerating fluids of high and low density. The perturbations initially grow linearly with time; this is followed by a nonlinear regime with the formation of bubbles of the light fluid penetrating the heavy one and with spikes of the heavy fluid into the light one. Eventually this evolves into turbulent mixing, which is detrimental to achieving the hot spot at the center of the implosion.

Computer simulations show that the Richtmyer–Meshkov instability (left) can be suppressed with a saddle-shaped magnetic field (right).

Li, Samtaney and Wheatley numerically investigated the RMI in the case of a converging cylindrical shock interacting with two interfaces that separated fluids of three densities. Previous research indicated that applying a magnetic field decreases the temperature required for ignition and reduces instability. The team studied changes in the flow field under the influence of a magnetic field shaped like a saddle; a topology previously identified as the most effective. By simulating this system with different ratios of densities between the three fluids and various magneticfield intensities, the team confirmed that the saddle-shaped magnetic field could indeed reduce the instability. However, they showed that the extent of the suppression varies on the interface: whether it was light to heavy or heavy to light. This in turn leads to a nonsymmetric growth of the perturbations. The degree of this asymmetry increases with increasing strength of the magnetic field. “The saddle magnetic field suppresses RMI; however, it also breaks the flow symmetry,” explains Samtaney. “Symmetry is very important for the implosion to achieve high temperature and density.” “We next hope to use a more advanced mathematical model of shock-driven instabilities in inertial confinement fusion that treats ions and electrons as separate fluids,” says Samtaney. Li, Y., Samtaney, R. & Wheatley, V. The Richtmyer-Meshkov instability of a double-layer interface in convergent geometry with magnetohydrodynamic. Matter and Radiation at Extremes 3, 207–218 (2018).

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Rapid-fire photography reveals how even a nanoscale amount of surface roughness can unleash microbubbles that may interfere with coating technology. An air bubble breakup that may compromise the performance of droplet-derived coatings has been uncovered by a team led by Sigurdur Thoroddsen and his Ph.D. student Kenneth Langley. Understanding what happens to droplets when they splash onto solid surfaces is important for applications ranging from ordinary spray painting to inkjet printed circuits. One challenge arises from the air cushion that is trapped underneath the drop during initial contact. Within a fraction of a second, this gas can be compressed and cause the droplet to rebound or adhere poorly to the target. From cameras that film at 5 million frames per second, the team’s images show how thick bands of microbubbles appear when water droplets strike surfaces that are only a few nanometers away from being completely flat. “We see that microbubbles emerge after the drop starts spreading, which isn’t what we anticipated,” says Langley. “The speed at which some of these bubbles form is also surprising—once nucleated, they grow to their ultimate size in a microsecond or less.”

The impact of drops onto a flat surface with a nanoparticle-based superhydrophobic coating has implications for industries that require ultra-dry surfaces, including coatings for ship hulls, to reduce friction and thus fuel consumption. Scale bars are 100 micrometers long.

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To unravel the mechanism of microbubble formation, the researchers used glass slides coated with a water-repelling film. Their time-resolved images demonstrated that the tiny bubbles appeared when the glass slide was coated with enough layers to produce rugged projections similar in size to the nanometer-scale air pocket. “If your application is sensitive to air entrapment, such as organic LED displays, it’s important to make the surface as smooth as possible,” says Langley. Langley, K.R., Li, E.Q., Vakarelski, I.U. & Thoroddsen, S.T. The air entrapment under a drop impacting on a nanorough surface. Soft Matter, 14, 7586 (2018).

“I f y o u r a p p l i c a t i o n is sensitive to air e n t r a p m e n t , i t ’s i m p o r t a n t t o m a ke t h e s u r f a c e a s s m o o t h a s p o s s i b l e .”

TROUBLE ON THE SURFACE BEGINS WITH A WAVE OF TINY BUBBLES

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