Stylolites mark dissolution surfaces where minerals from the host rock have been dissolved by large overburden stresses. The resulting boundary consists of reprecipitated, insoluble material, such as clay. Due to their mechanical contrast with the host rock, these discontinuities may disrupt sound waves as they pass through.

The finding came from a stroke of luck for the researchers. “We were using limestone blocks for another experimental lab study when we noticed that stylolites were present in our samples,” says Finkbeiner. “This inspired us to investigate their physical properties in more detail and find out how they influence acoustic wave propagation at the lab scale. Few studies have explored stylolites from this angle before.”

The team imaged the stylolites using X-ray tomography equipment to gather data on their three-dimensional morphologies and characterize their dimensions.

“Imaging these stylolites was tricky because they were rather thin and had geometrically very irregular surfaces,” notes Finkbeiner. “Also, to better understand how their mechanical properties contrast with the ambient host rock, we had to open up our rock specimens with a saw, chisel, and hammer to access the stylolites and measure their hardness.”

“With increasing stylolite thickness, acoustic waves scatter more strongly and introduce more noise into the wavefield,” says Finkbeiner. “In laboratory experiments, this has implications for monitoring hydraulic fracture propagation in rock samples that contain stylolites. Our results will help determine the best way to locate acoustic emissions inside lab-scale rock samples.”

The researchers are now conducting larger rock block tests. They use advanced fiber optics detection and refined data processing techniques to see whether these findings can be scaled up and repeated.

Huabin Zhang and his team at KAUST, together with colleagues from China and the United States, have developed a material that significantly boosts hydrogen peroxide production^[1]. “We proposed a convenient strategy to regulate the chemical state of a catalyst at the atomic level,” says Chengyang Feng from the KAUST team.

These systems generate hydrogen peroxide directly from water and oxygen in the air, using a semiconductor photocatalyst that harvests solar energy. When exposed to sunlight, the photocatalyst absorbs photons and generates charge carriers — electrons and holes. The photogenerated electrons participate in the oxygen reduction reaction (ORR) at the catalyst surface, reducing oxygen molecules to hydrogen peroxide.

The efficiency of this process is significantly enhanced by optimizing the surface properties of the photocatalyst and its interaction with light.

“The first global-level assessment of the number, size and properties of shallow-water tropical coral reefs suggest that restoration is more achievable than previously thought,” suggests KAUST faculty and marine ecologist, Carlos M. Duarte

Tropical coral reefs form some of the largest living structures on Earth, offering shelter and sustenance to numerous marine creatures, and providing livelihoods and food to coastal communities. However, these essential marine ecosystems are facing significant damage and degradation due to climate change and human activities.

The Kunming-Montreal Global Biodiversity Framework aims to halt and reverse global biodiversity loss by 2030, but scientists have been missing vital fundamental data on coral reefs that would enable viable restoration and protection projects to get underway.

“Where exactly are tropical coral reefs located? How large are they? What spatial patterns do they exhibit and why?” asks Duarte.

To answer these questions, Duarte has teamed up with scientists Alex Giménez-Romero and Manuel Matias at the Institute of Cross-Disciplinary Physics and Complex Systems (IFISC, UIB-SCIC) in Spain, to conduct an AI-based analysis of the vast Allen Coral Atlas database^[1]. The Allen Coral Atlas comprises hundreds of thousands of satellite images, gathered by the Planet satellites, which are then classified by AI to identify precise coral reef habitats from space.

However, it has been cumbersome to extract reef-specific information from the images. So Duarte and co-workers have used AI to identify individual reefs across the entire Atlas, and retrieve location, size, and shape for each of the reefs to examine their collective properties.

The team reports on 1.5 million coral reefs covering a total area of more than 50,000 km². Their analysis reveals that the spatial geometries of reefs follow three universal scaling laws, or ‘power laws’; in other words, reef growth and distribution follow the scaling and fractal patterns of the Fibonacci sequence.

“Fibonacci series are prevalent across nature, such as fern fronds that form spiral-like features, and even in the shape of the bubble ‘curtains’ that humpback whales produce during hunting,” says Duarte. “To see these scaling patterns replicated in coral reef geometries as seen from space is really exciting.”

The team showed that the size-frequency distribution, the inter-reef distance distribution and the area-perimeter relationship of each reef all follow power laws. Reefs tend to evolve from simple rounded shapes to become more complex, elongated and less compact as they grow. Their fractal geometries emerge with age, and these same patterns are replicated across the globe, regardless of location.

“These universal patterns hint at the nature of the biological and chemical processes driving the shape of coral reefs,” says Duarte. “To support marine biodiversity, the more complex and intricate the structures the better. These are important insights for guiding the morphology of restored reefs; they also provide specific constraints to test reef models.”

The team found that the characteristic (median) size of a coral reef is 0.3 hectares. This suggests that, to achieve global biodiversity goals, the area that needs to be restored in each reef is a maximum of a few hundred square meters. 

“Such relatively small areas could be restored, even with limited resources and time, by custodians and citizens committed to individual reefs” says Duarte. “Our paper brings coral reef conservation and restoration to the human scale. It may be feasible for us to reverse the damage we’ve done to these truly beautiful, vital ecosystems.”

 

A programming framework could streamline chip design by bridging the gap between conceptual design and practical execution^[1]. This may help address the ongoing challenge in the computer hardware industry of meeting the demand for high-performance, energy-efficient electronic devices at ever smaller scales.

This demand has long posed a challenge: it requires not only smaller transistors and microchips but also innovative new hardware architectures that provide the optimum arrangements of components for rapid data flow and processing. However, transforming a high-level design — exactly what we want a chip to do — into the low-level details of practical hardware is a lengthy, complex process requiring multiple iterations and collaboration across multiple teams.

In developing the framework, called Assassyn (ASynchronous Semantics for Architectural Simulation and SYNthesis), researchers—including Jian Weng from KAUST—incorporated both architectural simulation and real-world hardware implementation.

Digital computer systems contain interconnected information-storing modules called registers. Register-transfer-level (RTL) languages like Verilog represent the circuit connections between registers, while the designers focus on the overall behaviors of the circuit. This imposes a gap between the design process and the real implementation (the actual wiring of a chip).

“Most chip design research adopts two separate styles: performance is simulated, while power-per-area characteristics are estimated through a separate RTL implementation,” says Weng. “This means there is a mindset misalignment between design and implementation. When designing, you think about doing jobs at one stage and ‘pushing’ data to the next. When implementing in RTL, you need to translate it into a ‘pull’ style in your mind — the latter stage listens for the signal to pull data in.”

Most efficient chip designs include ‘pipelining’ architectures, which allow multiple tasks to be executed simultaneously, keeping many transistors active and saving time — analogous to a factory assembly line. A key challenge in pipeline implementation is the coordination between stages.

“Our insight is that the behavior of pipeline stages cannot take effect immediately,” says Weng. He and his co-workers found that the secret to unifying the design and implementation stages was that events do not all have to happen at the same time.

“In Assassyn we use asynchronous event handling, a widely adopted programming paradigm in website development,” says Weng. “When functions are called, they are not executed all at once. This asynchronicity is the key innovation that makes Assassyn work.”

The team’s evaluation showed that Assassyn generated accurate, high-performance RTL simulations, achieving an order of magnitude speedup over previous models. To avoid reinventing the wheel, Assassyn-generated RTL can directly fit into existing design tools. The results showed that the generated RTL matched the quality of laboriously handcrafted designs in terms of power, chip area, and performance.

“Many hardware design concepts have already converged to their optimal points over the past few decades,” says Weng. “Instead of manually programming every detail of the hardware implementation, some common behaviors can be abstracted in a high-level manner.”

“We are now actively working in several directions, including building new hardware using Assassyn, building better ecosystem support for Assassyn, and extending the abstraction of Assassyn for the next best hardware design and implementation,” concludes Weng.

 

Organic thermoelectric devices (OTEs) convert waste heat into useful electric power, but they are not yet efficient enough for practical use. KAUST researchers have now developed a tool that predicts the best solvent to use when processing the devices’ polymer films, significantly improving their power output^[1].

“Waste heat is present everywhere: industrial processes, car engines, air conditioners, and even in your cup of coffee, so it would be useful to recover a portion of this energy into electricity,” says Derya Baran, who led the team. “We want to use this to improve the energy autonomy of electronic devices, for example to recharge a battery without plugging it into a wall outlet.”

Conventional thermoelectric devices rely on inorganic semiconductors, such as bismuth telluride, but their high cost restricts them to niche applications. In contrast, OTEs rely on a polymer film that can be easily processed from solution to make potentially cheaper devices. These polymers form crystalline regions in the film and devices achieve the best performance when the regions line up edge-on because charge can move more easily from the hot end to the cold end of the device to generate a current.

But controlling polymer orientation has previously required costly or energy-intensive techniques. To further complicate the challenge, the device also requires additives known as dopants that add vital electrical charges to the polymer but also affect its crystallinity.

This led the KAUST team to select a solvent that helps the polymers to align while the film is being formed.

To avoid a lot of time-consuming experiments with different solvents, the researchers created a model to predict which solvent would produce the best film from a particular polymer. The model includes a series of parameters that describe how well a solvent would dissolve polymers and dopants, as well as the solvent’s boiling point. This approach depends on a concept called molecular-force-driven anisotropy (MFDA), which exploits the forces between solvent molecules, dopants and polymers to ensure these components pack together in the ideal way.

“This tool is very useful for predicting which solvent will render the polymer orientation that you need, while screening large databases of solvents. This saves a lot of time and resources on optimization through trial and error,” says team member Diego Rosas Villalva, currently based at the University of Bern in Switzerland.

Using the model, the researchers surveyed more than 10,000 solvents, looking for the ideal match for a polythiophene polymer and three dopants. They found that the common solvent chlorobenzene maximized the polymer’s desirable edge-on orientation. When they built an OTE using this recipe, it produced 20 times more power than a similar device prepared using a solvent called ortho-dichlorobenzene, the standard solvent typically used to build these devices.

The MFDA approach could be applied to a range of other polymer-based devices. “Orientation is a very important factor for every electronic device,” says Baran. “I think other researchers will use this strategy to understand how charges move inside organic electronic devices, and then to make these devices better.”

 

Hollow, pumpkin-shaped molecules can efficiently separate valuable hydrocarbons from crude oil, KAUST researchers have shown^[1]. These ‘molecular sieves’, known as cucurbiturils, could enable a more sustainable approach to producing raw materials for the chemicals industry.

Crude oil is a complex mixture of hydrocarbons vital for almost every aspect of life, from fuels to plastics. Cyclohexane, for example, is used in nylon production, but isolating it at sufficient purity typically involves multiple energy-intensive fractional distillation steps.

The KAUST team has now developed an alternative separation strategy based on cucurbiturils, named for their resemblance to pumpkins of the plant family Cucurbitaceae. These come in various sizes and have spherical cavities that can trap other molecules.

When the researchers dissolved a cucurbituril called CB[7] in water and mixed it with crude oil at room temperature and pressure, CB[7] pulled cyclohexane and a couple of closely related hydrocarbons into its cavity. The oil and water naturally separated into two layers so that the water could be removed along with CB[7] and its cargo. These hydrocarbons were then washed out of CB[7] using a common solvent.

Because the hydrocarbons and solvent have significantly different boiling points, they could be easily separated through simple and relatively energy-efficient distillation processes. “It requires much less energy than crude oil distillation, which involves many components with similar boiling points and complex interactions,” says Niveen M. Khashab, who led the research.

The process worked well under harsh chemical conditions — including acid, alkali, and salt — and the CB[7] and solvent could be recycled many times. “Thanks to the good recyclability of the aqueous CB[7] system, net water usage remains low,” adds team member Gengwu Zhang.

Distillation of crude oil is not the only method used to produce cyclohexane. Some cyclohexane is produced through a chemical reaction involving benzene, but separating them is challenging due to their similar boiling points. When the KAUST team tested CB[7] on a 50:50 mixture of benzene and cyclohexane, they found it could deliver cyclohexane of more than 99.6 percent purity after a single extraction.

They also tested CB[7] on a mixture called crude oil distillate, which includes about 2.5 percent cyclohexane alongside many other hydrocarbons with comparable boiling points. Again, the cucurbituril provided cyclohexane with a purity of over 99 percent.

“CB[7] binds cyclohexane so selectively because its spherical cavity closely matches the size and shape of the cyclohexane molecule, enabling strong and specific host-guest interactions,” explains Zhang. CB[7] is also easily synthesized from inexpensive ingredients and is highly stable, allowing it to be reused many times.

The researchers estimate that their CB[7]-based separation method could use approximately 57 to 82 percent less energy than conventional extractive distillation, making it a more sustainable and potentially cost-effective alternative. They now hope to tune the cavity size and binding properties of other hollow molecules to extract a broader range of components of crude oil.

“We are currently working on scaling up the process and exploring collaborations with industry,” says Khashab.

 

A near-complete genomic framework of wild Oryza species now provides insights into the evolution of the genus and offers new avenues for crop improvement and conservation efforts^[1].

The Oryza genus, containing related species of plants in the grass family, provides the world with one of the most important domesticated grain crops: rice. Oryza includes the Asian and African cultivated rice species (O. sativa and O. glaberrima), as well as 26 species of wild rice, which offer a rich, untapped source of genetic diversity for crop improvement.

This genomic resource, generated by a team of scientists including researchers from KAUST and Wageningen University in the Netherlands, is now publicly available and can be used for future neodomestication efforts: the generation of new rice varieties from wild relatives that possess natural resistance to abiotic and biotic stress, and are adapted to local climates.

“With climate change threatening global rice production, this was a critical moment to generate high-quality, chromosome-level reference genomes of the wild Oryza species. This resource is crucial to investigate evolutionary patterns in the genus and detect adaptive traits useful for crop improvement,” says Alice Fornasiero, a postdoctoral researcher who worked under the supervision of Rod Wing at KAUST.

To boost an existing Oryza genome reference dataset previously developed by Wing, Fornasiero and co-workers generated new chromosome-level genome assemblies of eleven wild Oryza species. These included two diploids (genomes with two copies of each chromosome) and nine tetraploids (with four chromosome sets organized into two subgenomes). This resource enabled the researchers to explore the genome size and composition of the wild Oryza species in the context of 15 million years of evolution in the genus.

“We merged the information from all the sequenced genomes to build a pangenome (a representation of the entire genus) and found that it consists of a stable ‘core’ portion shared by all the species and a ‘dispensable’ portion, malleable in size and composition across the species” says Fornasiero. “Our analysis added new evidence of the phylogenetic relationships between the species and refined the classification for one of them.”

The team also analyzed gene activity in O. coarctata, a species adapted to the saline conditions of coastal regions from Pakistan to Myanmar. They found that O. coarctata showed an unusual balance between its two subgenomes, with genes from one subgenome being expressed at higher levels over the other in a mosaic form. Taken together, the two subgenomes contribute equally to gene activity. This equilibrium may help explain the resistance of O. coarctata to salty environments, although additional work is needed to understand this mechanism, notes Fornasiero.

“Our extensive genomic resource will help scientists improve cultivated rice to meet global food security needs and tackle future agricultural and environmental challenges,” says Wing. “Genome editing techniques, such as CRISPR/Cas9, allow the introduction of precise modifications in the sequences of key genes for domestication, such as the genes controlling seed dispersal, grain size, flowering time, and plant height. This approach allows us to generate novel crops exhibiting domesticated traits that preserve original adaptations to local climates.”

The team will next focus on characterizing the genetic variation in wild Oryza populations to identify adaptive and resilience traits in specific local climates. In particular, they will examine wild rice species endemic to the American continent before extending this approach to other wild species of the genus.

 

Carbonate reef platforms are large sedimentary deposits built up from the remains of calcareous marine organisms, including corals and shell-dwelling creatures, and microbes that precipitate carbonate through their metabolic processes. The Red Sea has some of the world’s most spectacular fossilized carbonate platforms, offering scientists a unique opportunity to study the evolution of these structures in the context of a young ocean.

Now, researchers at KAUST have traced the development of carbonate platforms over the last 23 million years across the Northeastern Red Sea region^[1].

“Carbonate platforms are indicators of the location of past shorelines, as well as past temperatures and salinity. Their initiation or demise provides a record of major geological or environmental events,” says Tihana Pensa, who worked on the project with KAUST colleagues, including Guillaume Baby, under the supervision of Abdulkader Afifi. “By studying the history of platform formations, we can learn how marine ecosystems reacted to past environmental changes and what this may mean for their future.”

The Red Sea is a globally important region for carbonate platforms, hosting several “morphotypes” from offshore banks to platforms that have formed on salt domes. While previous studies focused on individual outcrop sites, the team wanted to understand platform development in the wider geological context of the entire Red Sea basin.

The team used surface and subsurface survey data, together with satellite imagery, to examine the evolution of four carbonate platforms onshore and one offshore in the Duba Basin. Fossilized shells of certain marine species, along with the strontium isotope composition of their shells, helped date the different platforms.

“The platforms developed in stages, shaped by the tectonic evolution of the Red Sea and changes to global sea-levels and salinity,” says Baby. “Twenty-three million years ago, the Red Sea was a narrow rift basin composed of tilted fault blocks. The oldest carbonates colonized only the shallowest parts of these blocks, where sunlight could support their growth.”

By around 16 million years ago, sediment accumulation in the rift basin had allowed coral-algal reefs to expand out in front of river deltas, notes Pensa. However, between 14 and 6 million years ago, all the reefs were killed by highly saline conditions as both the Red Sea and Mediterranean Sea began to dry up.

“After the Red Sea was reflooded from the Gulf of Aden six million years ago, healthy coral-algal reefs recolonized the shorelines, and these second-generation reefs still exist today,” says Pensa. “In some areas, the platforms slid offshore over a ductile layer of salt that lies beneath the surface – this process built tall, underwater carbonate platforms that are now capped by living reefs.”

Salt tectonics— the movement of subsurface salt layers over time due to pressure from surrounding rocks — played a considerable role in shaping the Red Sea’s carbonate platforms. “Some platforms developed above rising salt domes, while others were displaced from their original positions as they slid over mobile salt layers. This has created dynamic settings for carbonate growth,” notes Baby.

“This work links ancient and modern reefs,” says Afifi. “Understanding how reefs have responded to changes in seafloor depth, sea level, and seawater salinity helps us assess the risks coral reefs face today. Furthermore, buried reef platforms are typically porous and may contain oil and gas fields, while others could be suitable for carbon dioxide sequestration.”

 

A sensor that can measure hormone concentrations in plants precisely and in real-time with minimal damage can help understand how hormones affect plants’ response to disease and stress. With further development, it could also be part of an agricultural toolkit for early detection of disease or stress, enabling farmers to intervene before extensive crop damage.

Plant hormones regulate key aspects of the plant life cycle, including growth and environmental response. In this study, KAUST researchers focused on two hormones related to stress and disease response: salicylic acid and auxin^[1].

Existing techniques for measuring the concentration of these and other hormones rely on genetic engineering or destructive sampling and cannot be readily used in nonmodel plants. While effective for lab research, they are too laborious and expensive for use in agriculture. These techniques also provide a single snapshot in time rather than the possibility of continuous monitoring.

The new sensor overcomes these problems. It is an electrochemical sensor that detects the concentration of auxin and salicylic acid based on changes in the electro-oxidative current. Electrodes are placed on the surface of a leaf, and microneedles poke through the leaf’s outer surface. The platinum microneedles are coated with a matrix of carbon nanotubes and magnetite, making a complex surface that can bind with auxin and salicylic acid. When a voltage is applied across the electrodes, electrons are transferred from the hormones to the microneedles. The sensor measures the transfer of electrons—an electric current—to determine the concentration of the hormones.

Researchers showed that the sensor could measure auxin and salicylic acid individually and together in tobacco and Arabidopsis plants. Unlike other detection methods, the sensor can also be used with non-model plants, making it a promising tool for agricultural field applications..

Measuring salicylic acid and auxin levels can indicate whether a plant is responding to stress or fighting off disease. “This technology could be combined with other elements, such as sentinel plants engineered to be more susceptible to a specific type of stress,” explains Abdullah Bukhamsin, who led the study.

“This is an exciting advancement for plant science and agriculture,” says Khaled Salama, the study’s senior author. “Being able to monitor plant stress in real-time, without hurting the plant, provides a window into their responses to tough conditions. That’s especially important for countries like Saudi Arabia, where extreme heat and limited water are challenges for farmers. Tools like this could help make agriculture more sustainable and resilient here and worldwide.”

There remain hurdles to overcome before this technology could be used in the field. Repeated measurements are needed to track hormone levels over time, but the sensor’s effectiveness drops as material accumulates on the electrodes. An electrochemical cleaning method was introduced to significantly extend the sensor’s lifespan, but Bukhamsin says it is not yet sufficient for field use.

“It’s currently a great research tool. Our goal is to adapt it for use on farms,” says Bukhamsin. “Farmers would deploy it, detect stress, understand what’s happening, and intervene early. For example, if there’s a disease, they could catch it early enough to act before the pathogen spreads. This would reduce the area needing treatment and help mitigate both commercial and yield losses.”

 

Organic electrochemical transistors (OECTs) are innovative devices that could be made into implantable biosensors, or used to analyze biological samples to help diagnose illnesses. KAUST researchers have studied how the semiconducting polymers inside OECTs interact with ions in the samples — a crucial step in designing materials that tune the performance of these devices for particular applications^[1]

“The technology is rapidly advancing, and some OECT-based probes have already been used in clinical research settings, particularly in neuroscience for the brain–electronic device interfacing,” says Sahika Inal, who led the research. In biosensing applications, she explains, OECTs could operate directly in blood, sweat, or saliva; they might also be used to detect viruses or other pathogens in liquid samples.

OECTs contain a polymer film that can carry a current between two electrodes. These polymers are known as organic mixed ionic-electronic conductors. The film touches a water-based sample containing various ions, which are atoms or molecules bearing positive or negative charges. A third electrode delivers a voltage that drives one type of ion (for example, positive ions, known as cations) from the water into the polymer film, which increases the flow of current, producing a signal.

Researchers previously assumed the other ions in the electrolyte (negative ions, known as anions) were bystanders in this process and did not affect the device’s performance. But the KAUST team have now found that is not always true — these anions sometimes have a profound effect on how well OECTs perform.

The researchers made OECTs from two different semiconductive polymers. The first, P-100, is based on molecules with a water-repelling backbone, but with side chains that attract water molecules and the ions they carry. The second polymer, BBL, lacks these side chains.

The team tested the devices with water containing positive sodium ions and one of five different anions. With the BBL polymer, the type of anion made no difference to the OECT’s performance because all but the very largest anions infiltrate BBL films equally well. In contrast, the P-100 device showed considerable variation in performance. With anions based on a single atom – such as chloride or bromide – the P-100 device had a relatively good sensitivity. However, with larger anions, the performance declined by 90 percent over the course of an hour.

“By understanding these interactions more deeply, researchers can better tailor OECTs for specific applications, whether that means optimizing for stability, selectivity, signal amplification, or biocompatibility,” says team member David Ohayon, now at the National University of Singapore.

For instance, OECTs designed to measure ions involved in biological processes should be able to clearly differentiate between those ions. Other applications might require OECTs to operate independently of any ions present. “This is exactly why it is so crucial to understand how different ions affect device performance,” says Ohayon.

“The research may have wider implications for other devices,” adds Inal. “These findings could also inform the development of organic-based supercapacitors and batteries, where understanding how ions interact with the polymer matrix can help optimize charge storage and improve the stability of organic electrodes.”