While image denoising algorithms have undergone extensive research and advancements in the past decades, classical denoising techniques often necessitate numerous iterations for their inference, making them less suitable for real-time applications.
The advent of deep neural networks (DNNs) has ushered in a paradigm shift, enabling the development of non-iterative, feed-forward digital image denoising approaches.
These DNN-based methods exhibit remarkable efficacy, achieving real-time performance while maintaining high denoising accuracy. However, these deep learning-based digital denoisers incur a trade-off, demanding high-cost, resource- and power-intensive graphics processing units (GPUs) for operation.
In an article published in Light: Science & Applications, a team of researchers, led by Professors Aydogan Ozcan and Mona Jarrahi from University of California, Los Angeles (UCLA), U.S., and Professor Kaan Akşit from University College London (UCL), UK developed a physical image denoiser comprising spatially engineered diffractive layers to process noisy input images at the speed of light and synthesize denoised images at its output field-of-view without any digital computing.
Following a one-time training on a computer, the resulting visual processor with its passive diffractive layers is fabricated, forming a physical image denoiser that scatters out the optical modes associated with undesired noise or spatial artifacts of the input images.
Through its optimized design, this diffractive visual processor preserves the optical modes representing the desired spatial features of the input images with minimal distortions.
As a result, it instantly synthesizes denoised images within its output field-of-view without the need to digitize, store or transmit an image for a digital processor to act on it. The efficacy of this all-optical image denoising approach was validated by suppressing salt and pepper noise from both intensity- and phase-encoded input images.
Furthermore, this physical image denoising framework was experimentally demonstrated using terahertz radiation and a 3D-fabricated diffractive denoiser.
This all-optical image denoising framework offers several important advantages, such as low power consumption, ultra-high speed, and compact size.
The research team envisions that the success of these all-optical image denoisers can catalyze the development of all-optical visual processors tailored to address various inverse problems in imaging and sensing.
More information: Çağatay Işıl et al, All-optical image denoising using a diffractive visual processor, Light: Science & Applications (2024). DOI: 10.1038/s41377-024-01385-6
Putting hypersensitive quantum sensors in a living cell is a promising path for tracking cell growth and diagnosing diseases—even cancers—in their early stages.
Many of the best, most powerful quantum sensors can be created in small bits of diamond, but that leads to a separate issue: It’s hard to stick a diamond in a cell and get it to work.
“All kinds of those processes that you really need to probe on a molecular level, you cannot use something very big. You have to go inside the cell. For that, we need nanoparticles,” said University of Chicago Pritzker School of Molecular Engineering Ph.D. candidate Uri Zvi. “People have used diamond nanocrystals as biosensors before, but they discovered that they perform worse than what we would expect. Significantly worse.”
Zvi is the first author of a paper published in Proceedings of the National Academy of Sciences that tackles this issue. Together with researchers from UChicago PME and the University of Iowa, Zvi united insights from cellular biology, quantum computing, old-fashioned semiconductors and high-definition TVs to both create a revolutionary new quantum biosensor. In doing so, they shed light on a longstanding mystery in quantum materials.
By encasing a diamond nanoparticle with a specially engineered shell—a technique inspired by QLED televisions—the team created not only a quantum biosensor ideal for a living cell, but also uncovered new insights into how a material’s surface can be modified to enhance its quantum properties.
“It’s already one of the most sensitive things on Earth, and now they’ve figured out a way to enhance that further in a number of different environments,” said Zvi’s principal investigator, UChicago PME Prof. Aaron Esser-Kahn, a co-author of the paper.
A cell full of diamonds Qubits hosted in diamond nanocrystals maintain quantum coherence even when the particles are small enough to be “taken up” by a living cell—a good metaphor is the cell swallowing and chewing on them without spitting them out. But the smaller the diamond particles, the weaker the quantum signal.
“It excited people for a while that these quantum sensors can be brought into living cells and, in principle, be useful as a sensor,” said UChicago PME Asst. Prof. Peter Maurer, a co-author of the paper. “However, while these kind of quantum sensors inside of a big piece of bulk diamond have really good quantum properties, when they are in nano diamonds, the coherent properties, the quantum properties, are actually significantly reduced.”
Here, Zvi turned to an unlikely source for inspiration—quantum dot LED televisions. QLED TVs use vibrant fluorescent quantum dots to broadcast in rich, full colors. In the early days, the colors were bright but unstable, prone to suddenly blinking off.
“Researchers found that surrounding the quantum dots with carefully designed shells suppresses detrimental surface effects and increase their emission,” Zvi said. “And today you can use a previously unstable quantum dot as part of your TV.”
In a new paper, University of Chicago Pritzker School of Molecular Engineering researchers, including Asst. Prof. Peter Maurer (left) and first author and Ph.D. candidate Uri Zvi (right), and their collaborators created a revolutionary new quantum biosensor that sheds light on a longstanding question in quantum materials. Credit: Jason Smith Working with UChicago PME and Chemistry Department quantum dot expert Prof. Dmitri Talapin, a co-author of the paper, Zvi reasoned that since both sets of issues—the quantum dots’ fluorescence and the nanodiamond weakened signal—originated with the surface state, a similar approach might work.
But since the sensor is meant to go within a living body, not every shell would work. An immunoengineering expert, Esser-Kahn helped develop a silicon-oxygen (siloxane) shell that would both enhance the quantum properties and not tip off the immune system that something is awry.
“The surface properties of most of these materials are sticky and disordered in a way that the immune cells can tell it’s not supposed to be there. They look like a foreign object to an immune cell,” Esser-Kahn said. “Siloxane-coated things look like a big, smooth blob of water. And so the body is much more happy to engulf and then chew on a particle like that.”
Previous efforts to improve the quantum properties of diamond nanocrystals through surface engineering had shown limited success. As a result, the team expected only modest gains. Instead, they saw up to fourfold improvements in spin coherence.
That increase—as well as a 1.8-fold increase in fluorescence and separate significant increases to charge stability—was a riddle both baffling and enthralling.
Better and better “I would try to go to bed at night but stay up thinking ‘What’s happening there? The spin coherence is getting better—but why?” said University of Iowa Asst. Prof. Denis Candido, second author of the new paper. “I’d think ‘What if we do this experiment? What if we do this calculation?’ It was very, very exciting, and in the end, we found the underlying reason for the improvement of the coherence.”
The interdisciplinary team—bioengineer-turned-quantum-scientist Zvi, immunoengineer Esser-Kahn and quantum engineers Maurer and Talapin—brought Candido and University of Iowa Physics and Astronomy Prof. Michael Flatté in to provide some of the theoretical framework for the research.
“What I found really exciting about this is that some old ideas that were critical for semiconductor electronic technology turned out to be really important for these new quantum systems,” Flatté said.
They found that adding the silica shell didn’t just protect the diamond surface. It fundamentally altered the quantum behavior inside. The material interface was driving electron transfer from the diamond into the shell. Depleting electrons from the atoms and molecules that normally reduce the quantum coherence made a more sensitive and stable way to read signals from living cells.
This enabled the team to identify the specific surface sites that degrade coherence and make quantum devices less effective—solving a long-standing mystery in the quantum sensing field and opening new doors for both engineering innovation and fundamental research.
“The end impact is not just a better sensor, but a new, quantitative framework for engineering coherence and charge stability in quantum nanomaterials,” Zvi said.
A a view from inside the OMEGA target chamber during a direct-drive inertial fusion experiment at the University of Rochester’s Laboratory for Laser Energetics. Scientists fired 28 kilojoules of laser energy at small capsules filled with deuterium and tritium fuel, causing the capsules to implode and produce a plasma hot enough to initiate fusion reactions between the fuel nuclei. The temperatures achieved at the heart of these implosions are as high as 100 million degrees Celsius (180 million degrees Fahrenheit). The speed at which the implosion takes place is typically between 500 and 600 kilometers per second (1.1 to 1.35 million miles per hour). The pressures at the core are up to 80 billion times greater than atmospheric pressure. Credit: University of Rochester Laboratory for Laser Energetics photo / Eugene Kowaluk
Scientists from the University of Rochester’s Laboratory for Laser Energetics (LLE) led experiments to demonstrate an effective “spark plug” for direct-drive methods of inertial confinement fusion (ICF). In two studies published in Nature Physics, the authors discuss their results and outline how they can be applied at bigger scales with the hopes of eventually producing fusion at a future facility.
LLE is the largest university-based U.S. Department of Energy program and hosts the OMEGA laser system, which is largest academic laser in the world but still almost one hundredth the energy of the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in California.
With OMEGA, Rochester scientists completed several successful attempts to fire 28 kilojoules of laser energy at small capsules filled with deuterium and tritium fuel, causing the capsules to implode and produce a plasma hot enough to initiate fusion reactions between the fuel nuclei. The experiments caused fusion reactions that produced more energy than the amount of energy in the central hot plasma.
The OMEGA experiments use direct laser illumination of the capsule and differ from the indirect drive approach used on the NIF. When using the indirect drive approach, the laser light is converted into X-rays that in turn drive the capsule implosion. The NIF used indirect drive to irradiate a capsule with X-rays using about 2,000 kilojoules of laser energy. This led to a 2022 breakthrough at NIF in achieving fusion ignition—a fusion reaction that creates a net gain of energy from the target.
“Generating more fusion energy than the internal energy content of where the fusion takes place is an important threshold,” says lead author of the first paper Connor Williams ’23 Ph.D. (physics and astronomy), now a staff scientist at Sandia National Labs in radiation and ICF target design. “That’s a necessary requirement for anything you want to accomplish later on, such as burning plasmas or achieving ignition.”
By showing they can achieve this level of implosion performance with just 28 kilojoules of laser energy, the Rochester team is excited by the prospect of applying direct-drive methods to lasers with more energy. Demonstrating a spark plug is an important step, however, OMEGA is too small to compress enough fuel to get to ignition.
“If you can eventually create the spark plug and compress fuel, direct drive has a lot of characteristics that are favorable for fusion energy compared to indirect drive,” says Varchas Gopalaswamy ’21 Ph.D. (mechanical engineering), the LLE scientist who led the second study that explores the implications of using the direct-drive approach on megajoule-class lasers, similar to the size of the NIF. “After scaling the OMEGA results to a few megajoules of laser energies, the fusion reactions are predicted to become self-sustaining, a condition called ‘burning plasmas.'”
Gopalaswamy says that direct-drive ICF is a promising approach for achieving thermonuclear ignition and net energy in laser fusion.
“A major factor contributing to the success of these recent experiments is the development of a novel implosion design method based on statistical predictions and validated by machine learning algorithms,” says Riccardo Betti, LLE’s chief scientist and the Robert L. McCrory Professor in the Department of Mechanical Engineering and in the Department of Physics and Astronomy. “These predictive models allow us to narrow the pool of promising candidate designs before carrying out valuable experiments.”
The Rochester experiments required a highly coordinated effort between large number of scientists, engineers, and technical staff to operate the complex laser facility. They collaborated with researchers from the MIT Plasma Science and Fusion Center and General Atomics to conduct the experiments.
More information: C. A. Williams et al, Demonstration of hot-spot fuel gain exceeding unity in direct-drive inertial confinement fusion implosions, Nature Physics (2024). DOI: 10.1038/s41567-023-02363-2
V. Gopalaswamy et al, Demonstration of a hydrodynamically equivalent burning plasma in direct-drive inertial confinement fusion, Nature Physics (2024). DOI: 10.1038/s41567-023-02361-4
Image shows the ion trap used to control the location of computational and refrigerant ions. The device was produced by Sandia National Laboratories. Credit: Sandia National Laboratories.
A new cooling technique that utilizes a single species of trapped ion for both computing and cooling could simplify the use of quantum charge-coupled devices (QCCDs), potentially moving quantum computing closer to practical applications.
Using a technique called rapid ion exchange cooling, scientists at the Georgia Tech Research Institute (GTRI) have shown that they could cool a calcium ion—which gains vibrational energy while doing quantum computations—by moving a cold ion of the same species into close proximity. After transferring energy from the hot ion to the cold one, the refrigerant ion is returned to a nearby reservoir to be cooled for further use.
Conventional ion cooling for QCCDs involves the use of two different ion species, with cooling ions coupled to lasers of a different wavelength that do not affect the ions used for quantum computing. Beyond the lasers needed to control the quantum computing operations, this sympathetic cooling technique requires additional lasers to trap and control the refrigerant ions, and that both increases complexity and slows quantum computing operations.
“We have shown a new method for cooling ions faster and more simply in this promising QCCD architecture,” said Spencer Fallek, a GTRI research scientist. “Rapid exchange cooling can be faster because transporting the cooling ions requires less time than laser cooling two different species. And it’s simpler because using two different species requires operating and controlling more lasers.”
https://www.youtube.com/embed/Uj9ITEhh3Pc?color=whiteVideo shows how a computational ion can be cooled by bringing it near a refrigerant ion of the same atomic species. Credit: Georgia Tech Research Institute
The ion movement takes place in a trap maintained by precisely controlling voltages that create an electrical potential between gold contacts. But moving a cold atom from one part of the trap is a bit like moving a bowl with a marble sitting in the bottom.
When the bowl stops moving, the marble must become stationary—not rolling around in the bowl, explained Kenton Brown, a GTRI principal research scientist who has worked on quantum computing issues for more than 15 years.
“That’s basically what we’re always trying to do with these ions when we’re moving the confining potential, which is like the bowl, from one place to another in the trap,” he said. “When we’re done moving the confining potential to the final location in the trap, we don’t want the ion moving around inside the potential.”
Once the hot ion and cold ion are close to each other, a simple energy swap takes place and the original cold ion—heated now by its interaction with a computing ion—can be split off and returned to a nearby reservoir of cooled ions.
The GTRI researchers have so far demonstrated a two-ion proof-of-concept system, but say their technique is applicable to the use of multiple computing and cooling ions, and other ion species.
A single energy exchange removed more than 96% of the heat—measured as 102(5) quanta—from the computing ion, which came as a pleasant surprise to Brown, who had expected multiple interactions might be necessary. The researchers tested the energy exchange by varying the starting temperature of the computational ions and found that the technique is effective regardless of the initial temperature. They have also demonstrated that the energy exchange operation can be done multiple times.
Heat—essentially vibrational energy—seeps into the trapped ion system through both computational activity and from anomalous heating, such as unavoidable radio-frequency noise in the ion trap itself. Because the computing ion is absorbing heat from these sources even as it is being cooled, removing more than 96% of the energy will require more improvements, Brown said.
The researchers envision that in an operating system, cooled atoms would be available in a reservoir off to the side of the QCCD operations and maintained at a steady temperature. The computing ions cannot be directly laser-cooled because doing so would erase the quantum data they hold.
Excessive heat in a QCCD system adversely affects the fidelity of the quantum gates, introducing errors in the system. The GTRI researchers have not yet built a QCCD that uses their cooling technique, though that is a future step in the research. Other work ahead includes accelerating the cooling process and studying its effectiveness at cooling motion along other spatial directions.
The experimental component of the rapid exchange cooling experiment was guided by simulations done to predict, among other factors, the pathways that the ions would take in their journey within the ion trap. “We definitely understood what we were looking for and how we should go about achieving it based on the theory and simulations we had,” Brown said.
The unique ion trap was fabricated by collaborators at Sandia National Laboratories. The GTRI researchers used computer-controlled voltage generation cards able to produce specific waveforms in the trap, which has a total of 154 electrodes, of which the experiment used 48. The experiments took place in a cryostat maintained at about 4 degrees Kelvin.
Researchers Spencer Fallek (left) and Kenton Brown are shown with equipment used to develop a new technique for cooling ions in quantum devices. Credit: Sean McNeil, GTRI
GTRI’s Quantum Systems Division (QSD) investigates quantum computing systems based on individual trapped atomic ions and novel quantum sensor devices based on atomic systems. GTRI researchers have designed, fabricated, and demonstrated a number of ion traps and state-of-the-art components to support integrated quantum information systems. Among the technologies developed is the ability to precisely transport ions to where they are needed.
“We have very fine control of how the ions move, the speed at which they can be brought together, the potential they’re in when they are near one another, and the timing that’s necessary to do experiments like this,” said Fallek.
Other GTRI researchers involved in the project included Craig Clark, Holly Tinkey, John Gray, Ryan McGill and Vikram Sandhu. The research was done in collaboration with Los Alamos National Laboratory.
Kirigami is a traditional Japanese art form that entails cutting and folding paper to produce complex three-dimensional (3D) structures or objects. Over the past decades, this creative practice has also been applied in the context of physics, engineering, and materials science research to create new materials, devices and even robotic systems.
Researchers at Sichuan University and McGill University recently devised a new approach for the inverse engineering of kirigami, which does not rely on advanced computational tools and numerical algorithms. This new method, outlined in a paper published in Physical Review Letters, could simplify the design of intricate kirigami for a wide range of real-world applications.
“This work is a natural extension of our previous work on kirigami,” Damiano Pasini, senior corresponding author of the paper, told Phys.org.
“The first author, Chuan Qiao, is a former Ph.D. student of mine. During his Ph.D. under my supervision, Chuan worked on snapping interaction of thin shells and anisotropic morphing of kirigami. The study of the latter led to a paper published last year in Advanced Materials, where we adopted a unit cell approach to investigate the deformation of a kirigami made of rotating units with arbitrarily shaped triangles.”
In their previous studies, the researchers were able to better understand the role that the geometric parameters of slit patterns (e.g., internal angles and lengths) play in the anisotropic deployment of kirigami. To do this, they assessed changes in shape observed in the final deployment of kirigami by examining the length of the sides and internal angles of the triangular units.
“This triggered a set of interrelated questions, such as: how would a kirigami deform if we simply change the entire shape of the rotating unit in its entirety, as opposed to changing its geometric constituents individually, as we did in previous work? Is there a physical relation between the kirigami deformation and the shape of its rotating unit? And can this geometric relation establish an intuitive first-hand route for the inverse design of kirigami?” said Pasini.
“With these questions in mind, our goal then became twofold: to unveil the fundamental relation between the shape of the rotating units and the shape of the deployed kirigami and to leverage such a relation for the design of kirigami that foregoes the use of fairly sophisticated numerical methods currently used in the literature.”
In their new paper, Pasini and his colleagues showed that there is a simple relationship between the strain applied to a rotating unit (γ*max) and the shear deformation of a deployed triangle kirigami (γmax). Their proposed method to inversely design kirigami leverages this straightforward relationship.
The fundamental relationship between the strain applied to a rotating unit (γ*max) and the shear deformation of the deployed triangle kirigami (γmax). A shrink of the rotating units in their initial closed form corresponds to an expansion of the deployed kirigami. Credit: Qiao et al. “The key notion is that the shear strain applied to the initial rotating units, which shrink horizontally when we move from the left to the middle sketch, is in the opposite direction of the shear strain of the deployed triangle kirigami, which, in contrast, expands horizontally (once it deploys),” said Pasini.
“This insight can be leveraged for the inverse design of kirigami. By a simple geometric tuning of the shape of the rotating units with shear strains, we can achieve on-target deployment. The only basic operation we need is to use an area-preserving map to apply the shear strain.”
The new approach for the engineering of kirigami introduced by this team of researchers requires three key ingredients. These are the contracted shape of the rotating units, the shape of a deployed kirigami, and an area-preserving map outlining the transition from the deployed kirigami to its non-deployed (i.e., contracted) form.
“With the ingredients above, the shear strain of the deployed triangle kirigami can be programmed by applying a shear strain to the shape of the rotating units in the opposite direction,” said Pasini. “Our method can now forego any numerical computations and program the shear deformation of a kirigami specimen at will in a swift, versatile manner.”
To demonstrate the potential of their inverse design method, Pasini and his colleagues used it to produce three different types of morphing targets, namely the contracted shape, the deployed shape, and the internal trajectories of rotating units in kirigami.
This recent study shows a fundamental relationship between the deformation of kirigami and the shape of their rotating units, which can be utilized to design these structures. The team’s geometric design method could soon be used to create a wide range of kirigami designs that could help to tackle complex engineering challenges.
“This work brings ground-rule insights into morphing matter with rotating units and offers an intuitive, firsthand geometric route for the swift design of complex kirigami,” added Pasini. “Similar observations can also be drawn by inspecting the morphing of quadrilateral kirigami, hence showing the promise of this work to describe other kirigami patterns.”
Credit: Frontiers of Chemical Science and Engineering (2023). DOI: 10.1007/s11705-023-2373-1
Hydrogen is widely recognized as a promising clean energy source, primarily due to its high energy density and the absence of carbon emissions during its utilization. This characteristic makes hydrogen an ideal candidate for addressing the growing energy demand and mitigating the environmental impact associated with the excessive use of non-renewable fossil fuels over the past decades.
To harness renewable energy from sources like solar, wind, and tidal power, a compelling strategy involves the conversion of this volatile energy into hydrogen. This approach not only aids in meeting the energy demand gap but also contributes to the overall sustainability of human society.
Presently, overall water splitting (OWS) is considered a viable method for hydrogen production. OWS, powered by renewable energy, facilitates the generation of hydrogen through the hydrogen evolution reaction (HER) on the cathode.
However, the Faradic efficiency of hydrogen production is impeded by the anodic oxygen evolution reaction (OER), which is characterized by sluggish kinetics and high thermodynamic potential.
Consequently, there is a pressing need for the development of advanced electrocatalysts for OER or other oxidation reactions with swift kinetics and low thermodynamic potentials.
An alternative approach gaining traction is overall hydrazine splitting (OHzS) for hydrogen production, leveraging the anodic hydrazine oxidation reaction (HzOR). HzOR exhibits fewer electrons and faster kinetics compared to OER, making it a promising avenue. Nevertheless, a significant challenge remains in the synthesis of bifunctional electrocatalysts for both HER and HzOR with low overpotentials.
Recently, a research team in China introduced a novel solution in the form of a two-dimensional multifunctional layered double hydroxide derived from a metal-organic framework sheet precursor. This material is supported by nanoporous gold, providing high porosity. The study is published in the journal Frontiers of Chemical Science and Engineering.
Remarkably, this electrocatalyst demonstrates dual appealing activities for both HER and HzOR. In practical terms, the OHzS cell exhibits superior performance, requiring only a cell voltage of 0.984 V to deliver 10 mA∙cm-2, a notable improvement compared to the OWS system (1.849 V).
In addition, the electrolysis cell exhibits remarkable stability, operating continuously for more than 130 hours. This innovative approach not only enhances the efficiency of hydrogen production but also holds promise for a more sustainable and cleaner energy future.
Graphical abstract. Credit: Angewandte Chemie International Edition (2024). DOI: 10.1002/anie.202400161
Glass can be synthesized through a novel “crystal-liquid-glass” phase transformation. Crystalline materials can be fine-tuned for desired properties such as improved mass transfer and optical properties through coordination chemistry and grid chemistry design principles.
However, how to induce the local structural disorder of crystalline materials to achieve glass transition remains a challenge because most of them undergo decomposition before melting.
In the metal-organic framework system, the exploration of glassy states is limited to a few model compounds such as ZIF-4, ZIF-62 and ZIF-8. There is a need to break the limitation of metals and ligands in the “crystal-liquid-glass” process and to develop the glass synthesis pathway of universal crystalline materials.
In a study published in Angewandte Chemie International Edition, a research group led by Prof. Zhang Jian and Prof. Fang Weihui from Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences reported the meltable aluminum molecular rings with fluorescence and nonlinear optical properties.
Inspired by the characteristics of deep eutectic solvent (DES) mixtures involving significant depressions in melting points compared to their neat constituent components, the researchers designed and synthesized the first examples of meltable aluminum oxo clusters via lattice doping with DESs at the molecular level.
This kind of molecular ring compound undergoes a crystal-liquid-glass process after heating. The abundant and strong hydrogen bonds between the aluminum molecular ring, DES components and the lattice solvent in the structure are considered to be the root cause of the lower melting point. This lattice doping bonding method provides a general preparation method for the development of cluster glass.
The researchers determined the composition changes of the compounds before and after melting and quenching by modern characterization methods and in situ temperature monitoring (TG-IR-MS). They tried to mix DES solvent with an empty Al8 ring by physical doping, and found no melting phenomenon in the mixture after heating, which proves the importance of doping the DES component in the lattice, that is, DES component forms a “supracluster” structure with aluminum molecular ring.
Owing to the plasticity of the cluster glass “soft material,” the researchers explored its machinability and optical properties. They prepared the bubble-free glass film by a simple “hot pressing” method under atmospheric pressure, and well maintained the luminescence and third-order nonlinear effect similar to that of the original crystal.
The forming of this cluster glass film does not require additional mixed media, which is different from the traditional substrate bonding method, revealing the advantages of cluster glass.
This study demonstrates the potential of aluminum-related glass prepared by the third most abundant metal in the Earth’s crust, for sustainable development. The strategy combining the aluminum molecular ring and ionic liquid component overcomes the limitation of metal and ligand type of crystal glass, and provides a better approach for the study of “crystal-liquid-glass.”
More information: San-Tai Wang et al, Meltable Aluminum Molecular Rings with Fluorescence and Nonlinear Optical Properties, Angewandte Chemie International Edition (2024). DOI: 10.1002/anie.202400161
by Nick William Smith, Andrew John Fletcher and Warren McNabb, The Conversation
Vitamin B12 trade by country income classification, 1986-2020: H = high-income countries, UM = upper middle-income , LM = lower middle-income, L = low-income, ODU = origin or destination not recorded. Credit: Nick William Smith, CC BY-SA
Have you ever looked down at your breakfast, lunch or dinner and considered where the ingredients traveled from to reach your plate?
A basic sandwich in New Zealand can easily represent five countries: an Australian wheat and Indian sesame seed roll, Danish salami, local lettuce and cheese, seasoned with Vietnamese pepper.
And because your food travels a long way to reach you, so does your nutrition.
Research on global food trade—particularly trade in cereals—has a long history. More recently, researchers have begun considering the nutrients—energy, protein, vitamins, minerals—that move around the world within traded food.
As we learn more about the global trade in nutrients we can build a better picture of how these key dietary ingredients are distributed, and how they affect global population health.
Mapping global nutrient trade
The Sustainable Nutrition Initiative undertakes modeling research on the links between global food production and the nutrition of the global population.
Working with researchers at the University of São Paulo and State University of Campinas in Brazil, we have now published a broader analysis of global nutrient trade over time and its impact on health.
It shows the variation in nutrient trade between countries with differing wealth, and some positive links between nutrient trade and health.
Our team built a large data set of all flows of food for human consumption between 254 countries from 1986 to 2020. From this, we worked out the flows of 48 essential nutrients over that period.
As this is too much information for a single scientific paper, the team built an interactive app to let anyone explore the data.
The paper itself focused on a few key nutrients: protein, calcium, iron and vitamins A and B12. These are often used in analyses of food security (having reliable access to enough affordable, nutritious food) because of their importance to human health.
Some of these nutrients are under-supplied in many parts of the world, particularly low-income countries. At the same time, nutrient trade over the 35 years we analyzed has grown rapidly, as shown in the chart below for vitamin B12.
New Zealand protein exports by country and food group. Credit: Nick William Smith, CC BY-SA
The wealth and nutrient gap
High-income countries were the biggest importers of vitamin B12, but also the other nutrients analyzed, largely from trade with other high-income countries. This is despite those countries having only around 15% of the global population.
In contrast, low-income countries have little involvement in global trade of any nutrients. This limits their ability to improve dietary diversity and quality through food from outside their borders.
Most of New Zealand’s trading partners are in the higher-income brackets. Milk and meat dominate New Zealand protein exports, with China the major partner (see chart below).
The quantity of protein exported would meet the needs of nearly seven times New Zealand’s own population. In a country like China, of course, this is only a small fraction of the population.
In contrast, nearly 60% of New Zealand’s protein imports comes from Australia, largely in wheat and wheat products. And New Zealand imports enough protein to meet around half its population’s need.
We also analyzed the socioeconomic, demographic and health outcome data potentially associated with food consumption patterns and nutrient trade.
The findings suggest higher involvement in nutrient trade networks was significantly associated with improvements in infant mortality rates, lower prevalence of anemia in women of reproductive age, and greater life expectancy.
Food security and nutrition
It is concerning to see the low involvement of low-income countries in nutrient trade, particularly given the benefits it can bring for population health.
Our research provides context for how important traded nutrients are in meeting national population requirements. This knowledge can be used to identify weaknesses in the global food system, and which shocks (climatic, political or biological) might have the greatest consequences for nutrition.
These data can then be combined with other knowledge and modeling of food production, distribution and consumption at national levels to give a more complete view of food systems.
Food trade plays a key role in fostering food security and good nutrition. The trade has grown rapidly in both quantity and economic value over the past 35 years. Understanding its importance for healthy nutrition is essential.
A research team has discovered how to make a promising energy-harvesting material much more efficient—without relying on rare or expensive elements. The material, called β-Zn4Sb3, is a tellurium-free thermoelectric compound that can convert waste heat into electricity.
In their study published in Advanced Science, scientists used advanced neutron scattering techniques to peek inside the crystal and found something surprising: tiny heat vibrations (called phonons) were being disrupted by “rattling” atoms inside the structure. This phenomenon, known as phonon avoided crossing, dramatically slowed down how heat travels through the material.
Thanks to this effect, the material’s thermal conductivity dropped to extremely low levels—great news for thermoelectric performance. Even better, the researchers found that the single-crystal version of this material also conducts electricity better than its polycrystalline counterpart, reaching a high power conversion efficiency of 1.4%.
These results show that smart phonon control can lead to high-performance, eco-friendly materials for converting heat into power.
In thermoelectric materials, avoided crossing refers to the interaction between propagating phonons and localized vibrational modes, where their energy dispersions repel each other rather than intersect. This phenomenon occurs under specific conditions, such as crystal symmetries or vibrational mode couplings.
However, when researchers developed the single-crystal β-Zn4Sb3, they observed an unexpected, avoided crossing, revealing unique phonon behavior that deviated from conventional thermoelectric materials.
The article explores the thermoelectric performance of single-crystalline β-Zn4Sb3, a tellurium-free material, by uncovering the microscopic mechanisms that lead to its ultralow lattice thermal conductivity (κL).
Using inelastic neutron scattering (INS), the researchers provide the first experimental observation of avoided crossing between longitudinal acoustic phonons and low-energy rattling modes. This interaction causes a significant reduction in phonon group velocity—from over 4000 m/s to about 591 m/s—and shortens phonon lifetimes to under 1 picosecond, both of which contribute to strongly suppressed heat transport.
The β-Zn4Sb3 single crystal achieves a κL of approximately 0.36 W/m·K in the 300–600 K range and a peak thermoelectric figure of merit (zT) of 1.0 at 623 K. Additionally, device-level testing shows a conversion efficiency (η) of 1.4% in a single-leg thermoelectric module—one of the highest reported for undoped Zn4Sb3.
Structural characterizations via TEM reveal a grain-boundary-free lattice with uniformly distributed moiré fringes, attributed to Zn concentration variations.
These nanoscale features further enhance phonon scattering without degrading electronic performance. Compared to polycrystalline samples, the single crystal exhibits significantly better electrical conductivity due to fewer defects and optimized carrier mobility.
“This discovery shows how heat flow can be engineered to design more efficient and sustainable energy technologies—without depending on scarce resources,” says Prof. Hsin-Jay Wu.
The proposed mechanism for the H2O2 production by PEI-GCN/Au biomimetic-photo-coupled catalysis. Credit: Zhang Huiru
A research group led by Prof. Wan Yinhua from the Institute of Process Engineering of the Chinese Academy of Sciences has developed a catalyst with dual photocatalytic and biomimetic catalytic activity for the production of hydrogen peroxide (H2O2).
The strategy involves loading gold nanoparticles (AuNPs) onto graphite carbon nitride (GCN) nanosheets using polyethyleneimine (PEI) as a “bridge.” The study was published in the Chemical Engineering Journal.
H2O2, recognized as an environmentally friendly oxidant, is extensively used in various fields such as medical treatment, environmental restoration, fine chemicals, and electronics industries. However, the conventional method of H2O2 production relies on the anthraquinone process, which has several drawbacks including high energy consumption, the use of organic solvents, and safety hazards. Therefore, there is a pressing need to develop a sustainable and eco-friendly manufacturing process for H2O2.
Solar-driven photocatalysis is a promising alternative strategy for H2O2 production, and GCN is a popular choice in the field of photocatalysis due to its straightforward synthesis, cost-effectiveness, stable physical and chemical properties, and broad light absorption spectrum. However, GCN nanosheets alone have limited performance in photocatalytic H2O2 production in pure water due to the high energy barrier of water dissociation and low separation efficiency of charge carriers.
Hole sacrificial agents (acting as electron donors) such as ethanol, isopropanol, and benzyl alcohol are commonly used to improve the selectivity of oxygen reduction. However, the addition of organic agents has adverse environmental impacts, which is not conducive to the sustainability of H2O2 production. Therefore, it is crucial to engineer a GCN material with enhanced electron-hole pair separation efficiency to facilitate water oxidation and oxygen reduction.
“Inspired by photo-enzyme-coupled catalytic system in chloroplasts, we developed a composite catalyst by loading AuNPs (enzyme mimics) on GCN (photocatalyst) nanosheets using PEI as the ‘bridge’ (PEI-GCN/Au),” Prof. Wan said.
The introduction of PEI and AuNPs helps adjust the electronic structure of GCN, facilitating the rapid separation of photogenerated carriers. The surface plasmon resonance of AuNPs, when excited by incident light, promotes the activation of glucose molecules, elevating their reactivity with O2 and improving the glucose oxidase-mimicking catalytic production of H2O2. The grafting of PEI and the addition of glucose enhance the O2 adsorption on the catalyst surface.
The PEI-GCN/Au composite demonstrates exceptional H2O2 production efficiency (270 μmol g-1 h-1) under visible light irradiation, using only glucose, H2O and O2 as reactants. As a result, both the biomimetic catalytic and photocatalytic reduction of O2 to H2O2 are enhanced, achieving a significant synergistic enhancement effect of 175%.
“This work establishes a paradigm of coupling biomimetic catalysis and photocatalysis for co-production of chemicals. It not only provides insights into the development of materials for efficient H2O2 production, but also introduces an innovative concept for integrating biocatalysis and photocatalysis,” said Prof. Luo Jianquan, the corresponding author of this study.
More information: Huiru Zhang et al, Biomimetic-photo-coupled catalysis for boosting H2O2 production, Chemical Engineering Journal (2024). DOI: 10.1016/j.cej.2024.149183
