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KAUST Professor of Earth Science and Engineering, Martin Mai, has been named Editor-in-Chief of Bulletin of the Seismological Society of America (BSSA).

First published in 1911, BSSA is the premier journal of advanced research in earthquake seismology and related disciplines. BSSA publishes original papers advancing our understanding of seismology and seismic hazard analyses, as well as review articles summarizing important research topics. The journal's format allows papers to fully explore research topics in detail.

For further information, please visit

https://www.seismosoc.org/news/p-martin-mai-named-bssa-editor-in-chief/

https://www.seismosoc.org/publications/bssa/

Research

Professor Mai's research addresses the physics of earthquakes and the complexity of earthquake phenomena, with focus on earthquake-source imaging, dynamic rupture modeling, and earthquake mechanics. His work extends to strong ground-motion properties and high-performance computing-enabled physics-based seismic (including scattering in heterogeneous media) and tsunami simulations, and thereby spans from fundamental earthquake physics to earthquake-engineering applications.

Another major part of Professor Mai's research involves seismic data to image the structure of the Earth's crust and upper mantle beneath the Arabian plate, with the goal to help unravel the geodynamics of the Arabian plate and the Red Sea.

He has published more than 100 peer-reviewed papers, and since 2003 has supervised more than 35 graduate students (Ph.D. and M.Sc.) and over 15 postdoctoral researchers. He served as president of the Seismology Division of the European Geosciences Union from 2015 to 2019.

Read more about Professor Mai's full profile.

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The inclusion of biological uncertainty and the latest case data can significantly improve the prediction accuracy of standard epidemiological models of virus transmission, new research led by KAUST and the Kuwait College of Science and Technology (KCST) has shown.

Modern mathematical epidemic models have been tested like never before during the COVID-19 pandemic. These models use mathematics to describe the various biological and transmission processes involved in an epidemic. However, when such factors are highly uncertain, such as during the emergence of a new virus like COVID-19, the predictions can be unreliable.

"The susceptible-exposed-infected-recovered model, SEIR, is a standard mathematical approach for forecasting the spread of an epidemic in a population," says Rabih Ghostine, formerly of KAUST and now at KCST. "This model is based on several assumptions, such as homogeneous mixing of the population and the omission of migration, births or deaths from causes other than the epidemic. The parameters in the traditional SEIR model also do not allow for quantification of uncertainty, being single values reflecting the modeler's best guess."

"We wanted to develop a robust mathematical model that takes into account such uncertainties and incorporates epidemic data in order to enhance forecasting accuracy," explained Ghostine.

Ghostine, along with KAUST's Ibrahim Hoteit and fellow researchers, developed an extended SEIR model compromising seven compartments: susceptible, exposed, infectious, quarantined, recovered, deaths and vaccinated. They then added uncertainty definitions and a data assimilation process to drive progressive improvement of the model.

"Our data assimilation approach exploits new incoming observations to calibrate the model with recent information in order to continuously provide improved predictions, and also to estimate uncertainties," says Ghostine. "This is a popular framework in the atmospheric and ocean research communities and is at the basis of all operational weather and ocean modeling."

The model uses an "ensemble" approach, in which a set of predictions is generated across different parameter uncertainties. This ensemble is then integrated forward in time to forecast the future state. A correction step is performed to update the forecast with the latest data. Validation using real data for Saudi Arabia showed the model to provide reliable forecasts for up to 14 days in advance.

"Mathematical models can play an important role in understanding and predicting COVID-19 transmission as well as provide crucial information to policymakers to implement appropriate measures and efficient strategies to control the pandemic spread and mitigate its impact," says Hoteit. "Our method, which we developed to simulate the COVID-19 spread in Saudi Arabia, can also be applied to forecast the spread of any pandemic in a population."

- KAUST Discovery

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KAUST Professor of Chemical Science, Niveen M. Khashab, has been named a Fellow of the Royal Society of Chemistry (FRSC).

The Royal Society of Chemistry (RSC) is the United Kingdom's professional body for chemists and the largest organization in Europe for advancing the chemical sciences. The designation Fellow of the Royal Society of Chemistry (FRSC) is given to elected Fellows who have made an outstanding contribution to the advancement of chemical sciences, or to the advancement of the chemical sciences as a profession. 

At KAUST, Professor Khashab is affiliated with the Advanced Membranes & Porous Materials Research Center.

Research

"Professor Khashab's research interests focus on the synthesis, and applications of "smart" programmable assemblies that mimic natural designs. These nanomaterials are assembled using supramolecular tools with emphasis on the controlled release and delivery aspects for biomedical applications and molecular recognition with pore and surface engineering for industrial separations. Read Professor Khashab's full profile.

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An electrode coating just one molecule thick can significantly enhance the performance of an organic photovoltaic cell, KAUST researchers have found. The coating outperforms the leading material currently used for this task and may pave the way for improvements in other devices that rely on organic molecules, such as light-emitting diodes and photodetectors.

Unlike the most common photovoltaic cells that use crystalline silicon to harvest light, organic photovoltaic cells (OPVs) rely on a light-absorbing layer of carbon-based molecules. Although OPVs cannot yet rival the performance of silicon cells, they could be easier and cheaper to manufacture at a very large scale using printing techniques.

When light enters a photovoltaic cell, its energy frees a negative electron and leaves behind a positive gap, known as a hole. Different materials then gather the electrons and holes and guide them to different electrodes to generate an electrical current. In OPVs, a material called PEDOT:PSS is widely used to ease the transfer of generated holes into an electrode; however, PEDOT:PSS is expensive, acidic and can degrade the cell's performance over time.

The KAUST team has now developed a better alternative to PEDOT:PSS. They use a much thinner coating of a hole-transporting molecule called Br-2PACz, which binds to an indium tin oxide (ITO) electrode to form a single-molecule layer. The organic cell using Br-2PACz achieved a power conversion efficiency of 18.4 percent, whereas an equivalent cell using PEDOT:PSS reached only 17.5 percent.

"We were very surprised indeed by the performance enhancement," says Yuanbao Lin, Ph.D. student and member of the team. "We believe Br-2PACz has the potential to replace PEDOT:PSS due to its low cost and high performance."

Br-2PACz increased the cell's efficiency in several ways. Compared with its rival, it caused less electrical resistance, improved hole transport and allowed more light to shine through to the absorbing layer. Br-2PACz also improved the structure of the light-absorbing layer itself, an effect that may be related to the coating process.

The coating could even improve the recyclability of the solar cell. The researchers found that the ITO electrode could be removed from the cell, stripped of its coating and then reused as if it was new. In contrast, PEDOT:PSS roughens the surface of the ITO so that it performs poorly if reused in another cell. "We anticipate this will have a dramatic impact on both the economics of OPVs and the environment," says Thomas Anthopoulos, who led the research.

- KAUST Discovery

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Rising temperatures are increasingly affecting the quality of life in many regions, setting new challenges for architects, urban planners and healthcare systems. Researchers at KAUST have analyzed discomfort due to outdoor heat across Saudi Arabia and neighboring regions to help understand and combat the problem.

"Living conditions in the Kingdom have been particularly affected by the changing climate," says Hari Dasari, first author of the paper. He also emphasizes the unique challenges facing the Hajj pilgrimage visits by several million people each year. Between 2014 and 2018, the Hajj occurred in summer months when the average temperature often exceeded 40 degrees Celsius with 80 percent humidity.

The team examined the variability and trends in a measure called the thermal discomfort index (DI), computed from temperature and humidity records collected from 1980 to 2018. The DI evaluates how these two factors combine to cause heat stress and discomfort. 

Surprisingly, most cities in Saudi Arabia recorded an improvement in DI levels during the past 20 years, but significant exceptions were Yanbu, Makkah, Medina and Taif. The danger of increasing DI values in the Makkah region was confirmed by examining clinical records, which suggest a correlation with heat-related deaths during the Hajj pilgrimage.

"Many of us expected that the rising temperatures due to global warming and rapid growth in urbanization during recent decades should have reduced human comfort levels over KSA," says Dasari. A valuable insight from the research is the discovery that the situation is more complicated, with many regional variations worthy of further exploration.

Increased heat discomfort levels were concentrated mainly in neighboring regions of the Arabian Gulf, including the United Arab Emirates, Oman and Qatar.

Ibrahim Hoteit, leader of the research group, says the findings will help regional authorities, engineers and architects to plan the most effective developments in infrastructure, building design and healthcare interventions to improve safety and comfort across the region.

"We now plan to develop an atlas of DI values with risk maps indicating the trends through an online interactive visualization and analysis interface that provides real-time access for nonexpert users, and also a forecasting system to support the management of various outdoor activities and minimize health-related chronic symptoms." says Hoteit.

The team expect the further development of this research will also be critically important for supporting several large-scale projects currently being developed in Saudi Arabia, including the city of NEOM and the Red Sea Project and AMAALA tourism initiatives.

- KAUST Discovery

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KAUST Professor of Material Science and Engineering at the PSE division and member of the KAUST Catalysis Center, Osman M. Bakr, has been awarded the 2021 Kroll Medal & Prize by the Institute of Materials, Minerals & Mining (IOM3).

The Kroll Medal & Prize is presented for significant contribution that has enhanced the scientific understanding of materials chemistry as applied to the industrial production of inorganic materials.

The Institute of Materials, Minerals and Mining (IOM3) is the United Kingdom's professional body for materials and its members come from all levels within the industry and academia. With over 15,000 members, IOM3 spans a broad spectrum of materials and covers all aspects of materials production, processing, design and end use. IOM3's roots go back to 1869.

Research

Professor Bakr's research interests are concerned with the physics and chemistry of hybrid and inorganic materials. His group works on the design and self-assembly of such materials to generate breakthrough applications in optoelectronic devices and renewable energy. 

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A remote-sensing technique that can detect real-time changes in subsurface environments has undergone successful testing in the desert just outside the KAUST campus in Thuwal, Saudi Arabia.

To avoid the time-consuming and destructive impact of drilling, geologists are increasingly turning to an approach known as seismic imaging. This procedure uses sonic sources at many different locations to send acoustic waves deep underground and then measures how long it takes for the waves to return to receivers on the surface. The travel time of the waves depends on properties such as the hardness or porosity of materials they pass through, and so this method can easily identify unique subsurface features, such as pockets of water.

However, conventional seismic imaging is still too slow to detect real-time geologic events, notes KAUST geophysicist Gerard Schuster. "For a conventional seismic experiment, you need many different angular views to accurately estimate the properties of each substructure, which demands many hours to deploy and excite seismic sources over hundreds of different locations," he says.

For the past 20 years, Schuster has been working on a solution to this issue by focusing on how the cyclical patterns of acoustic waves begin to lag or lead each other after passing through an underground material. These changes, known as phase differences, can be inverted by seismic interferometry to provide high-resolution structural information while requiring far fewer audio sources.

"This approach requires much less effort," says Shuster. "Taking the time differences between the phases allows you to answer questions about the hardness and softness of geology with just a few experiments instead of hundreds."

In their latest work, Schuster and colleagues performed a controlled time-lapse experiment to validate the capabilities of their seismic interferometry technology. First, the team set up an array of audio sources and receivers over a dry sand dune. Then, they injected 12 tons of water into the dune over a few hours while recording nearly one hundred interferometric measurements for each source location. This data was transformed every two minutes into snapshots of subsurface water flow as it percolated through substructural layers several meters under the surface.

"Our three-dimensional simulations of the experiments convinced us that what we saw wasn't a false reading," says Schuster. "The initial impact of these findings can be useful for environmental engineers who require rapid and inexpensive monitoring of the subsurface — for example, real-time imaging of leaky dams, or efficient Martian or lunar seismic surveys."

- KAUST Discovery

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​Lithium is a vital element in the batteries that power electric vehicles, but soaring lithium demand is expected to exhaust land-based reserves by 2080. KAUST researchers have now developed an economically viable system that can extract high-purity lithium from seawater.

The oceans contain about 5,000 times more lithium than the land but at extremely low concentrations of about 0.2 parts per million (ppm). Larger ions, including sodium, magnesium and potassium, are all present in seawater at much higher concentrations; however, previous research efforts to tease lithium from this mixture have yielded little.

The KAUST team solved this problem with an electrochemical cell containing a ceramic membrane made from lithium lanthanum titanium oxide (LLTO). Its crystal structure contains holes just wide enough to let lithium ions pass through while blocking larger metal ions. "LLTO membranes have never been used to extract and concentrate lithium ions before," says postdoc Zhen Li, who developed the cell.

The cell contains three compartments. Seawater flows into a central feed chamber, where positive lithium ions pass through the LLTO membrane into a side compartment that contains a buffer solution and a copper cathode coated with platinum and ruthenium. Meanwhile, negative ions exit the feed chamber through a standard anion exchange membrane, passing into a third compartment containing a sodium chloride solution and a platinum-ruthenium anode.

The researchers tested the system using seawater from the Red Sea. At a voltage of 3.25V, the cell generates hydrogen gas at the cathode and chlorine gas at the anode. This drives the transport of lithium through the LLTO membrane, where it accumulates in the side-chamber. This lithium-enriched water then becomes the feedstock for four more cycles of processing, eventually reaching a concentration of more than 9,000 ppm. Adjusting the pH of this solution delivers solid lithium phosphate that contains mere traces of other metal ions — pure enough to meet battery manufacturers' requirements.

The researchers estimate that the cell would need only US$5 of electricity to extract 1 kilogram of lithium from seawater. The value of hydrogen and chlorine produced by the cell would more than offset this cost, and residual seawater could also be used in desalination plants to provide freshwater.

"We will continue optimizing the membrane structure and cell design to improve the process efficiency," says group leader Zhiping Lai. His team also hopes to collaborate with the glass industry to produce the LLTO membrane at large scale and affordable cost.

- KAUST Discovery

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A catastrophic drop in atmospheric ozone levels around the tropics is likely to have contributed to a bottleneck in the human population around 60 to 100,000 years ago, an international research team has suggested. The ozone loss, triggered by the eruption of the Toba supervolcano located in present-day Indonesia, might solve an evolutionary puzzle that scientists have been debating for decades.

"Toba has long been posited as a cause of the bottleneck, but initial investigations into the climate variables of temperature and precipitation provided no concrete evidence of a devastating effect on humankind," says Sergey Osipov at the Max Planck Institute for Chemistry, who worked on the project with KAUST's Georgiy Stenchikov and colleagues from King Saud University, NASA and the Max Planck Institute for Chemistry.

"We point out that, in the tropics, near-surface ultraviolet (UV) radiation is the driving evolutionary factor. Climate becomes more relevant in the more volatile regions away from the tropics," says Stenchikov.

Large volcanic eruptions emit gases and ash that create a sunlight-attenuating aerosol layer in the stratosphere, causing cooling at the Earth's surface. This "volcanic winter" has multiple knock-on effects, such as cooler oceans, prolonged El Niño events, crop failures and disease.

"The ozone layer prevents high levels of harmful UV radiation reaching the surface," says Osipov. "To generate ozone from oxygen in the atmosphere, photons are needed to break the O₂ bond. When a volcano releases vast amounts of sulfur dioxide (SO₂), the resulting volcanic plume absorbs UV radiation but blocks sunlight. This limits ozone formation, creating an ozone hole and heightening the chances of UV stress."

The team examined UV radiation levels after the Toba eruption using the ModelE climate model developed by NASA GISS (Goddard Institute for Space Studies). They simulated the possible after-effects of different sizes of eruptions. Running such a model is computationally intensive, and Osipov is grateful for the use of KAUST's supercomputer, Shaheen II, and associated expertise.

Their model suggests that the Toba SO₂ cloud depleted global ozone levels by as much as 50 percent. Furthermore, they found that the effects on ozone are significant, even under relatively small eruption scenarios. The resulting health hazards from higher UV radiation at the surface would have significantly affected human survival rates.

"The UV stress effects could be similar to the aftermath of a nuclear war," says Osipov. "For example, crop yields and marine productivity would drop due to UV sterilization effects. Going outside without UV protection would cause eye damage and sunburn in less than 15 minutes. Over time, skin cancers and general DNA damage would have led to population decline."

- KAUST Discovery