Aurelia Butler

Noise-canceling headphones have gotten very good at creating an auditory blank slate. But allowing certain sounds from a wearer’s environment through the erasure still challenges researchers. The latest edition of Apple’s AirPods Pro, for instance, automatically adjusts sound levels for wearers — sensing when they’re in conversation, for instance — but the user has little control over whom to listen to or when this happens.
A University of Washington team has developed an artificial intelligence system that lets a user wearing headphones look at a person speaking for three to five seconds to “enroll” them. The system, called “Target Speech Hearing,” then cancels all other sounds in the environment and plays just the enrolled speaker’s voice in real time even as the listener moves around in noisy places and no longer faces the speaker.
The team presented its findings May 14 in Honolulu at the ACM CHI Conference on Human Factors in Computing Systems. The code for the proof-of-concept device is available for others to build on. The system is not commercially available.
“We tend to think of AI now as web-based chatbots that answer questions,” said senior author Shyam Gollakota, a UW professor in the Paul G. Allen School of Computer Science & Engineering. “But in this project, we develop AI to modify the auditory perception of anyone wearing headphones, given their preferences. With our devices you can now hear a single speaker clearly even if you are in a noisy environment with lots of other people talking.”
To use the system, a person wearing off-the-shelf headphones fitted with microphones taps a button while directing their head at someone talking. The sound waves from that speaker’s voice then should reach the microphones on both sides of the headset simultaneously; there’s a 16-degree margin of error. The headphones send that signal to an on-board embedded computer, where the team’s machine learning software learns the desired speaker’s vocal patterns. The system latches onto that speaker’s voice and continues to play it back to the listener, even as the pair moves around. The system’s ability to focus on the enrolled voice improves as the speaker keeps talking, giving the system more training data.
The team tested its system on 21 subjects, who rated the clarity of the enrolled speaker’s voice nearly twice as high as the unfiltered audio on average.
This work builds on the team’s previous “semantic hearing” research, which allowed users to select specific sound classes — such as birds or voices — that they wanted to hear and canceled other sounds in the environment.
Currently the TSH system can enroll only one speaker at a time, and it’s only able to enroll a speaker when there is not another loud voice coming from the same direction as the target speaker’s voice. If a user isn’t happy with the sound quality, they can run another enrollment on the speaker to improve the clarity.
The team is working to expand the system to earbuds and hearing aids in the future.
Additional co-authors on the paper were Bandhav Veluri, Malek Itani and Tuochao Chen, UW doctoral students in the Allen School, and Takuya Yoshioka, director of research at AssemblyAI. This research was funded by a Moore Inventor Fellow award, a Thomas J. Cabel Endowed Professorship and a UW CoMotion Innovation Gap Fund. More

Many of today’s quantum devices rely on collections of qubits, also called spins. These quantum bits have only two energy levels, the ‘0’ and the ‘1’. However, spins in real devices also interact with light and vibrations known as bosons, greatly complicating calculations. In a new publication in Physical Review Letters, researchers in Amsterdam demonstrate a way to describe spin-boson systems and use this to efficiently configure quantum devices in a desired state.
Quantum devices use the quirky behaviour of quantum particles to perform tasks that go beyond what ‘classical’ machines can do, including quantum computing, simulation, sensing, communication and metrology. These devices can take many forms, such as a collection of superconducting circuits, or a lattice of atoms or ions held in place by lasers or electric fields.
Regardless of their physical realisation, quantum devices are typically described in simplified terms as a collection of interacting two-level quantum bits or spins. However, these spins also interact with other things in their surroundings, such as light in superconducting circuits or oscillations in the lattice of atoms or ions. Particles of light (photons) and vibrational modes of a lattice (phonons) are examples of bosons.
Unlike spins, which have only two possible energy levels (‘0’ or ‘1’), the number of levels for each boson is infinite. Consequently, there are very few computational tools for describing spins coupled to bosons. In their new work, physicists Liam Bond, Arghavan Safavi-Naini and Jiří Minář of the University of Amsterdam, QuSoft and Centrum Wiskunde & Informatica work around this limitation by describing systems composed of spins and bosons using so-called non-Gaussian states. Each non-Gaussian state is a combination (a superposition) of much simpler Gaussian states.
Each blue-red pattern in the image above represents a possible quantum state of the spin-boson system. “A Gaussian state would look like a plain red circle, without any interesting blue-red patterns,” explains PhD candidate Liam Bond. An example of a Gaussian state is laser light, in which all light-waves are perfectly in sync. “If we take many of these Gaussian states and start overlapping them (so that they’re in a superposition), these beautifully intricate patterns emerge. We were particularly excited because these non-Gaussian states allow us to retain a lot of the powerful mathematical machinery that exists for Gaussian states, whilst enabling us to describe a far more diverse set of quantum states.”
Bond continues: “There are so many possible patterns that classical computers often struggle to compute and process them. Instead, in this publication we use a method that identifies the most important of these patterns and ignores the others. This lets us study these quantum systems, and design new ways of preparing interesting quantum states.”
The new approach can be exploited to efficiently prepare quantum states in a way that outperforms other traditionally used protocols. “Fast quantum state preparation might be useful for a wide range of applications, such as quantum simulation or even quantum error correction,” notes Bond. The researchers also demonstrate that they can use non-Gaussian states to prepare ‘critical’ quantum states which correspond to a system undergoing a phase transition. In addition to fundamental interest, such states can greatly enhance the sensitivity of quantum sensors.
While these results are very encouraging, they are only a first step towards more ambitious goals. So far, the method has been demonstrated for a single spin. A natural, but challenging extension is to include many spins and many bosonic modes at the same time. A parallel direction is to account for the effects of the environment disturbing the spin-boson systems. Both of these approaches are under active development. More

Researchers have developed a method to make adaptive and eco-friendly sensors that can be directly and imperceptibly printed onto a wide range of biological surfaces, whether that’s a finger or a flower petal.
The method, developed by researchers from the University of Cambridge, takes its inspiration from spider silk, which can conform and stick to a range of surfaces. These ‘spider silks’ also incorporate bioelectronics, so that different sensing capabilities can be added to the ‘web’.
The fibres, at least 50 times smaller than a human hair, are so lightweight that the researchers printed them directly onto the fluffy seedhead of a dandelion without collapsing its structure. When printed on human skin, the fibre sensors conform to the skin and expose the sweat pores, so the wearer doesn’t detect their presence. Tests of the fibres printed onto a human finger suggest they could be used as continuous health monitors.
This low-waste and low-emission method for augmenting living structures could be used in a range of fields, from healthcare and virtual reality, to electronic textiles and environmental monitoring. The results are reported in the journal Nature Electronics.
Although human skin is remarkably sensitive, augmenting it with electronic sensors could fundamentally change how we interact with the world around us. For example, sensors printed directly onto the skin could be used for continuous health monitoring, for understanding skin sensations, or could improve the sensation of ‘reality’ in gaming or virtual reality application.
While wearable technologies with embedded sensors, such as smartwatches, are widely available, these devices can be uncomfortable, obtrusive and can inhibit the skin’s intrinsic sensations.
“If you want to accurately sense anything on a biological surface like skin or a leaf, the interface between the device and the surface is vital,” said Professor Yan Yan Shery Huang from Cambridge’s Department of Engineering, who led the research. “We also want bioelectronics that are completely imperceptible to the user, so they don’t in any way interfere with how the user interacts with the world, and we want them to be sustainable and low waste.”
There are multiple methods for making wearable sensors, but these all have drawbacks. Flexible electronics, for example, are normally printed on plastic films that don’t allow gas or moisture to pass through, so it would be like wrapping your skin in cling film. Other researchers have recently developed flexible electronics that are gas-permeable, like artificial skins, but these still interfere with normal sensation, and rely on energy- and waste-intensive manufacturing techniques.

3D printing is another potential route for bioelectronics since it is less wasteful than other production methods, but leads to thicker devices that can interfere with normal behaviour. Spinning electronic fibres results in devices that are imperceptible to the user, but without a high degree of sensitivity or sophistication, and they’re difficult to transfer onto the object in question.
Now, the Cambridge-led team has developed a new way of making high-performance bioelectronics that can be customised to a wide range of biological surfaces, from a fingertip to the fluffy seedhead of a dandelion, by printing them directly onto that surface. Their technique takes its inspiration in part from spiders, who create sophisticated and strong web structures adapted to their environment, using minimal material.
The researchers spun their bioelectronic ‘spider silk’ from PEDOT:PSS (a biocompatible conducting polymer), hyaluronic acid and polyethylene oxide. The high-performance fibres were produced from water-based solution at room temperature, which enabled the researchers to control the ‘spinnability’ of the fibres. The researchers then designed an orbital spinning approach to allow the fibres to morph to living surfaces, even down to microstructures such as fingerprints.
Tests of the bioelectronic fibres, on surfaces including human fingers and dandelion seedheads, showed that they provided high-quality sensor performance while remaining imperceptible to the host.
“Our spinning approach allows the bioelectronic fibres to follow the anatomy of different shapes, at both the micro and macro scale, without the need for any image recognition,” said Andy Wang, the first author of the paper. “It opens up a whole different angle in terms of how sustainable electronics and sensors can be made. It’s a much easier way to produce large area sensors.”
Most high-resolution sensors are made in an industrial cleanroom and require toxic chemicals in a multi-step and energy-intensive fabrication process. The Cambridge-developed sensors can be made anywhere and use a tiny fraction of the energy that regular sensors require.

The bioelectronic fibres, which are repairable, can be simply washed away when they have reached the end of their useful lifetime, and generate less than a single milligram of waste: by comparison, a typical single load of laundry produces between 600 and 1500 milligrams of fibre waste.
“Using our simple fabrication technique, we can put sensors almost anywhere and repair them where and when they need it, without needing a big printing machine or a centralised manufacturing facility,” said Huang. “These sensors can be made on-demand, right where they’re needed, and produce minimal waste and emissions.”
The researchers say their devices could be used in applications from health monitoring and virtual reality, to precision agriculture and environmental monitoring. In future, other functional materials could be incorporated into this fibre printing method, to build integrated fibre sensors for augmenting the living systems with display, computation, and energy conversion functions. The research is being commercialised with the support of Cambridge Enterprise, the University’s commercialisation arm.
The research was supported in part by the European Research Council, Wellcome, the Royal Society, and the Biotechnology and Biological Sciences Research Council (BBSRC), part of UK Research and Innovation (UKRI). More

In the early 2010s, LightSquared, a multibillion-dollar startup promising to revolutionize cellular communications, declared bankruptcy. The company couldn’t figure out how to prevent its signals from interfering with those of GPS systems.
Now, Penn Engineers have developed a new tool that could prevent such problems from ever happening again: an adjustable filter that can successfully prevent interference, even in higher-frequency bands of the electromagnetic spectrum.
“I hope it will enable the next generation of wireless communications,” says Troy Olsson, Associate Professor in Electrical and Systems Engineering (ESE) at Penn Engineering and the senior author of a new paper in Nature Communications that describes the filter.
The electromagnetic spectrum itself is one of the modern world’s most precious resources; only a tiny fraction of the spectrum, mostly radio waves, representing less than one billionth of one percent of the overall spectrum, is suitable for wireless communication.
The bands of that fraction of the spectrum are carefully controlled by the Federal Communications Commission (FCC), which only recently made available the Frequency Range 3 (FR3) band, including frequencies from about 7 GHz to 24 GHz, for commercial use. (One hertz is equivalent to a single oscillation in an electromagnetic wave passing a point each second; one gigahertz, or GHz, is a billion such oscillations per second.)
To date, wireless communications have mostly used lower-frequency bands. “Right now we work from 600 MHz to 6 GHz,” says Olsson. “That’s 5G, 4G, 3G.” Wireless devices use different filters for different frequencies, with the effect that covering all frequencies or bands requires large numbers of filters that take up substantial space. (The typical smartphone includes upwards of 100 filters, to ensure that signals from different bands don’t interfere with one another.)
“The FR3 band is most likely to roll out for 6G or Next G,” says Olsson, referring to the next generation of cellular networks, “and right now the performance of small-filter and low-loss switch technologies in those bands is highly limited. Having a filter that could be tunable across those bands means not having to put in another 100+ filters in your phone with many different switches. A filter like the one we created is the most viable path to using the FR3 band.”
One complication posed by using higher-frequency bands is that many frequencies have already been reserved for satellites. “Elon Musk’s Starlink works in those bands,” notes Olsson. “The military — they’ve already been crowded out of many lower bands. They’re not going to give up radar frequencies that sit right in those bands, or their satellite communications.”

As a result, Olsson’s lab — in collaboration with colleagues Mark Allen, Alfred Fitler Moore Professor in ESE, and Firooz Aflatouni, Associate Professor in ESE, and their respective groups — designed the filter to be adjustable, so that engineers can use it to selectively filter different frequencies, rather than have to employ separate filters. “Being tunable is going to be really important,” Olsson continues, “because at these higher frequencies you may not always have a dedicated block of spectrum just for commercial use.”
What makes the filter adjustable is a unique material, “yttrium iron garnet” (YIG), a blend of yttrium, a rare earth metal, along with iron and oxygen. “What’s special about YIG is that it propagates a magnetic spin wave,” says Olsson, referring to the type of wave created in magnetic materials when electrons spin in a synchronized fashion.
When exposed to a magnetic field, the magnetic spin wave generated by YIG changes frequency. “By adjusting the magnetic field,” says Xingyu Du, a doctoral student in Olsson’s lab and the first author of the paper, “the YIG filter achieves continuous frequency tuning across an extremely broad frequency band.”
As a result, the new filter can be tuned to any frequency between 3.4 GHz and 11.1 GHz, which covers much of the new territory the FCC has opened up in the FR3 band. “We hope to demonstrate that a single adaptable filter is sufficient for all the frequency bands,” says Du.
In addition to being tunable, the new filter is also tiny — about the same size as a quarter, in contrast to previous generations of YIG filters, which resembled large packs of index cards.
One reason the new filter is so small, and therefore could potentially be inserted into mobile phones in the future, is that it requires very little power. “We pioneered the design of a zero-static-power, magnetic-bias circuit,” says Du, referring to a type of circuit that creates a magnetic field without requiring any energy beyond the occasional pulse to readjust the field.

While YIG was discovered in the 1950s, and YIG filters have existed for decades, the combination of the novel circuit with extremely thin YIG films micromachined in the Singh Center for Nanotechnology dramatically reduced the new filter’s power consumption and size. “Our filter is 10 times smaller than current commercial YIG filters,” says Du.
In June, Olsson and Du will present the new filter at the 2024 Institute of Electrical and Electronics Engineers (IEEE) Microwave Theory and Techniques Society (MTT-S) International Microwave Symposium, in Washington, D.C.
This study was conducted at the University of Pennsylvania School of Engineering and Applied Science. It was supported by a grant from the Defense Advanced Research Projects Agency (FA8650-21-1-7010) and made use of resources sponsored by the National Science Foundation National Nanotechnology Coordinated Infrastructure Program (NNCI-1542153). More

Lighting a gas grill, getting an ultrasound, using an ultrasonic toothbrush — these actions involve the use of materials that can translate an electric voltage into a change in shape and vice versa.
Known as piezoelectricity, the ability to trade between mechanical stress and electric charge can be harnessed widely in capacitors, actuators, transducers and sensors like accelerometers and gyroscopes for next-generation electronics. However, integrating these materials into miniaturized systems has been difficult due to the tendency of electromechanically active materials to — at the submicrometer scale, when the thickness is just a few millionths of an inch — get “clamped” down by the material they are attached to, which significantly dials down their performance.
Rice University researchers and collaborators at the University of California, Berkeley have found that a class of electromechanically active materials called antiferroelectrics may hold the key to overcoming performance limitations due to clamping in miniaturized electromechanical systems. A new study published in Nature Materials reports that a model antiferroelectric system, lead zirconate (PbZrO3), produces an electromechanical response that can be up to five times greater than that of conventional piezoelectric materials even in films that are only 100 nanometers (or 4 millionths of an inch) thick.
“We’ve been using piezoelectric materials for decades,” said Rice materials scientist Lane Martin, who is the corresponding author on the study. “Recently there has been a strong motivation to further integrate these materials into new types of devices that are very small — as you would want to do for, say, a microchip that goes inside your phone or computer. The problem is that these materials are typically just less usable at these small scales.”
According to current industry standards, a material is considered to have very good electromechanical performance if it can undergo a 1% change in shape — or strain — in response to an electric field. For an object that measures 100 inches in length, for instance, getting 1 inch longer or shorter represents 1% strain.
“From a materials science perspective, this is a significant response, since most hard materials can only change by a fraction of a percent,” said Martin, the Robert A. Welch Professor, professor of materials science and nanoengineering and director of the Rice Advanced Materials Institute.
When conventional piezoelectric materials are scaled down to systems less than a micrometer (1,000 nanometers) in size, their performance generally deteriorates significantly due to the interference of the substrate, which dampens their ability to change shape in response to electric field or, conversely, to generate voltage in response to a change in shape.

According to Martin, if electromechanical performance were rated on a scale of 1-10 — where 1 is lowest performance and 10 is the industry standard of 1% strain — then clamping is typically expected to bring conventional piezoelectrics’ electromechanical response down from a 10 to the 1-4 range.
“To understand how clamping impacts motion, first picture being in a middle seat on an airplane with no one on either side of you — you’d be free to adjust your position if you get uncomfortable, overheated, etc.,” Martin said. “Now picture the same scenario, except now you’re seated between two huge offensive linemen from Rice’s football team. You’d be ‘clamped’ between them such that you really couldn’t meaningfully adjust your position in response to a stimulus.”
The researchers wanted to understand how very thin films of antiferroelectrics — a class of materials that remained understudied until recently due to a lack of access to “model” versions of the materials and to their complex structure and properties — changed their shape in response to voltage and whether they were likewise susceptible to clamping.
First, they grew thin films of the model antiferroelectric material PbZrO 3 with very careful control of the material thickness, quality and orientation. Next, they performed an array of electrical and electromechanical measurements to quantify the responses of the thin films to applied electric voltage.
“We found the response was considerably larger in the thin films of antiferroelectric material than what is achieved in similar geometries of traditional materials,” said Hao Pan, a postdoctoral researcher in Martin’s research group and lead author on the study.
Measuring shape change at such small scales was not an easy feat. In fact, optimizing the measurement setup required so much labor the researchers documented the process in a separate publication.

“With the perfected measurement setup, we can get a resolution of two picometers — that’s about a thousandth of a nanometer,” Pan said. “But just showing that a shape change happened doesn’t mean we understand what’s going on, so we had to explain it. This was one of the first studies to reveal the mechanisms behind this high performance.”
With support from their collaborators at the Massachusetts Institute of Technology, the researchers used a state-of-the-art transmission electron microscope to observe the nanoscale material shapeshift with atomic resolution in real time.
“In other words, we watched the electromechanical actuation as it was happening, so we could see the mechanism for the large shape changes,” Martin said. “What we found was that there is an electric voltage-induced change in the crystal structure of the material, which is like the fundamental building unit or single type of Lego block from which the material is built. In this case, that Lego block gets reversibly stretched with applied electric voltage, giving us a big electromechanical response.”
Surprisingly, the researchers found that not only does clamping not interfere with material performance, but it in fact enhances it. Together with collaborators at Lawrence Berkeley National Laboratory and Dartmouth College, they recreated the material computationally in order to get another view of how the clamping affects the actuation under applied electric voltage.
“Our results are the culmination of years of work on related materials, including the development of new techniques to probe them,” Martin said. “By figuring out how to make these thin materials work better, we’re hoping to enable the development of smaller and more powerful electromechanical devices or microelectromechanical systems (MEMS) — and even nanoelectromechanical systems (NEMS) — that use less energy and can do things we never thought possible before.” More

Concierge services built on artificial intelligence have the potential to improve how hotels and other service businesses interact with customers, a new paper suggests.
In the first work to introduce the concept, researchers have outlined the role an AI concierge, a technologically advanced assistant, may play in various areas of the service sector as well as the different forms such a helper might embody.
Their paper envisions a virtual caretaker that, by combining natural language processing, behavioral data and predictive analytics, would anticipate a customer’s needs, suggest certain actions, and automate routine tasks without having to be explicitly commanded to do so.
Though such a skilled assistant is still years away, Stephanie Liu, lead author of the paper and an associate professor of hospitality management at The Ohio State University, and her colleagues drew insight from several contemporary fields, including service management, psychology, human-computer interaction and ethics research, to detail what opportunities and challenges might arise from having an AI concierge manage human encounters.
“The traditional service industry uses concierges for high-end clients, meaning that only a few people have access to them,” Liu said. “Now with the assistance of AI technology, everybody can have access to a concierge providing superior experiences.”
On that premise, the benefits of incorporating AI into customer service are twofold: It would allow companies to offer around-the-clock availability and consistency in their operations as well as improve how individuals engage with professional service organizations, she said.
Moreover, as the younger workforce gravitates to more tech-oriented jobs and global travel becomes more common, generative AI could be an apt solution to deal with the escalating demands of evolving hospitality trends, said Liu.

“The development of AI technology for hotels, restaurants, health care, retail and tourism has a lot of potential,” she said.
The paper was published recently in the Journal of Service Management.
Despite the social and economic benefits associated with implementing such machines, how effective AI concierges may be at completing a task is dependent on both the specific situation and the type of interface consumers use, said Liu.
There are four primary forms a smart aide might take, each with distinctive attributes that would provide consumers with different levels of convenience, according to Liu.
The first type is a dialogue interface that uses only text or speech to communicate, such as ChatGPT, a conversational agent often used to make inquiries and garner real-time assistance. Many of these interactive devices are already used in hotels and medical buildings for contactless booking or to connect consumers with other services and resources.
The second is a virtual avatar that employs a vivid digital appearance and a fully formed persona to foster a deeper emotional connection with the consumer. This method is often utilized for telehealth consultations and online learning programs.

The third iteration is a holographic projection wherein a simulated 3D image is brought into the physical world. According to the paper, this is ideally suited for scenarios where the visual impact is desired, but physical assistance itself is not necessary.
The paper rounds out the list by suggesting an AI concierge that would present as a tangible, or touchable robot. This form would offer the most human-like sensory experiences and would likely be able to execute multiple physical tasks, like transporting heavy luggage.
Some international companies have already developed these cutting-edge tools for use in a limited capacity. One robotic concierge, known as Sam, was designed to aid those in senior living communities by helping them check in, make fall risk assessments and support staff with non-medical tasks. Another deployed at South Korea’s Incheon International Airport helped consumers navigate paths to their destination and offered premier shopping and dining recommendations.
Yet as advanced computing algorithms become more intertwined in our daily lives, industry experts will likely have to consider consumer privacy concerns when deciding when and where to implement these AI systems. One way to deal with these issues would be to create the AI concierge with limited memory or other safewalls to protect stored personal data, such as identity and financial information, said Liu.
“Different companies are at different stages with this technology,” said Liu. “Some have robots that can detect customers’ emotions or take biometric inputs and others have really basic ones. It opens up a totally different level of service that we have to think critically about.”
What’s more, the paper notes that having a diversity of concierge options available for consumers to choose from is also advantageous from a mental health standpoint.
Because AI is viewed as having less agency than their human counterparts, it might help mitigate psychologically uncomfortable service situations that could arise because of how consumers feel they might be perceived by a human concierge. This reduced apprehension regarding the opinion of a machine may encourage heightened comfort levels and result in more favorable responses about the success of the AI concierge, said Liu.
Ultimately, there’s still much multidisciplinary testing to be done to ensure these technologies can be applied in a widespread and equitable manner. Liu adds that future research should seek to determine how certain design elements, such as the perceived gender, ethnicity or voice of these robotic assistants, would impact overall consumer satisfaction. More

Whereas π-stacking systems involving aromatic compounds are quite common, those made from antiaromatic units are rare. In a recent study, researchers from Japan developed modified norcorrole molecules whose side chains favored the formation of columnar π-stacking structures. Using these compounds, they produced liquid crystals with high electrical conductivity and thermotropic properties. Their findings open up new design avenues for materials useful in electronics, sensing, optics, and biomedicine.
In organic chemistry, π-stacking systems are supramolecular structures that arise due to the dispersion force, a type of intermolecular noncovalent interaction. They are a common occurrence in nature; the stabilized structure of DNA is a very prominent example of a π-stacking system, and so are the arrangement of amino acids in certain proteins. Interestingly, π-stacking can be leveraged in the design of materials with useful electronic and optical properties. These include organic semiconductors of various kinds, as well as conjugated polymers for sensing and biomedical applications.
Thus far, a good portion of technologically relevant π-stacking system has been limited to aromatic compounds, which have inherent π-electron clouds. On the other hand, antiaromatic compounds, though promising candidates for developing electric conductors, have been scarcely reported as the building units of π-stacking systems.
Surprisingly, in a recent study, a research team led by Professor Hiromitsu Maeda from Ritsumeikan University, Japan, reported a novel antiaromatic π-stacking system that enabled the formation of a highly conductive liquid crystal. Their findings were published on April 16, 2024, in the journal Chemical Science. Worth noting, this paper was co-authored by Prof. Go Watanabe from Kitasato University, Prof. Shu Seki from Kyoto University, and Prof. Hiroshi Shinokubo from Nagoya University.
The reported compounds in question are NiII-coordinated norcorroles with modified aryl moieties as side chains. Previously, achieving π-stacking in similar norcorroles failed because hydrogen-bonding interactions between the side chains opposed the face-to-face stacking of the planar antiaromatic units. This time, however, the research team had an ingenious idea. “We hypothesized that the introduction of side interacting moieties with less directionality would enhance the stacking between norcorrole units,” explains Prof. Maeda. “Thus, we attempted the simple introduction of aliphatic chains, which induce van der Waals interactions. These interactions can be effective for modulating the stacking structure of a material,” adds Prof. Maeda.
As evidenced through various experiments and molecular dynamics simulations, the proposed strategy worked as intended. The norcorrole units formed columnar structures through the stacking of arrangements known as ‘triple-decker.’ In these arrangements, a planarized molecule is sandwiched between two slightly bowl-shaped molecules.
Using the proposed molecular design, the researchers then synthesized liquid crystals. Thanks to the triple-decker stacking, a liquid crystal exhibited remarkable electricconductivity as well as thermotropicity; that is, an order parameter that depends on temperature. “The control of molecular interactions based on molecular design and synthesis, as demonstrated in our study, will be crucial for future applications,” remarks Prof. Maeda. “Properties such as high electric conductivity in liquid crystals may be used for the fabrication of electronic devices. In addition, stimuli-responsive behaviors in soft materials can be used to modulate relevant properties, like photoluminescence, according to pressure and temperature,” explains Prof. Maeda.
Taken together, the findings of this study bring to light a promising strategy for designing new compounds based on molecular assemblies of antiaromatic units. With any luck, this will open up new avenues for materials design, ultimately leading to better organic electronics, optoelectronics, and sensing devices. More

Across nature, animals from swarming insects to herding mammals can organize into seemingly choreographed motion. Over the last two decades, scientists have discovered that these coordinated movements arise from each animal following simple rules about where their neighbors are located. Now, scientists studying zebrafish have shown that neighbors might also be moving to the same beat. The team revealed that fish swimming in pairs took turns to move; and, they synchronized the timing of these movements in a two-way process known as reciprocity. Then, in virtual reality experiments, the team could confirm that reciprocity was key to driving collective motion: by implementing this rhythmic rule, they could recreate natural schooling behavior in fish and virtual conspecifics. The study published in Nature Communications was led by scientists from the Cluster of Excellence Collective Behaviour at the University of Konstanz and the Max Planck Institute of Animal Behavior in Germany (MPI-AB).
The results provide further mechanistic detail to our understanding of how animals self-organize into moving collectives. “We show that it takes two fish to tango,” says first author Guy Amichay, who conducted the work while a doctoral student at MPI-AB. “Fish are coordinating the timing of their movements with that of their neighbor, and vice versa. This two-way rhythmic coupling is an important, but overlooked, force that binds animals in motion.”
The synchrony of the swarm
Animals moving in synchrony are the most conspicuous examples of collective behavior in nature; yet many natural collectives synchronize not in space, but in time — fireflies synchronize their flashes, neurons synchronize their firing, and humans in concert halls synchronize the rhythm of clapping.
Amichay and the team were interested in the intersection of the two; they were curious to see what rhythmic synchrony might exist in animal movement. “There’s more rhythm to animal movement than you might expect,” says Amichay, who is now a postdoctoral researcher at Northwestern University, USA. “In the real world most fish don’t swim at fixed speeds, they oscillate.”
Using pairs of zebrafish as a study system, Amichay analyzed their swimming to describe the precise pattern of motion. He found that fish, although moving together, did not swim at the same time. Rather they alternated such that one moved, then the other moved, “like two legs walking,” he says.
The team then looked into how fish managed to alternate. They generated a computational model with a simple rule of thumb: double the delay of your neighbor.

The rule of reciprocity
The next step was to test this model computationally, or in silico. They set one agent to beat with fixed movement bouts, like a metronome. The other agent responded to the first by implementing the ‘double the delay’ rhythmic rule. But in this one-way interaction, the agents did not move in the alternating pattern seen in real fish. When both agents responded to each other, however, they reproduced the natural alternation pattern. “This was the first indication that reciprocity was crucial,” says Amichay.
But reproducing natural behavior in a computer was not where the study ended. The team turned to virtual reality to confirm that the principle they uncovered would also work in real fish. “Virtual reality is a revolutionary tool in animal behavior studies because it allows us to circumvent the curse of causality,” says Iain Couzin, a Speaker at the Cluster of Excellence Collective Behaviour at the University of Konstanz and a Director at MPI-AB.
In nature many traits are linked and so it is extremely difficult to pinpoint the cause of an animal’s behavior. But using virtual reality, Couzin says it is possible to “precisely perturb the system” to test the effect of a particular trait on an animal’s behavior.
A single fish was put into a virtual environment with a fish avatar. In some trials the avatar was set to swim like a metronome, ignoring the behavior of the real fish. In these trials the real fish did not swim in the natural alternating pattern with the avatar. But when the avatar was set to respond to the real fish, in a two-way reciprocal relationship, they recovered its natural alternating behavior.
Turn-taking partners
“It’s fascinating to see that reciprocity is driving this turn-taking behavior in swimming fish,” says co-author Máté Nagy, who leads the MTA-ELTE Collective Behavior Research Group at the Hungarian Academy of Sciences, “because it’s not always the case in biological oscillators.” Fireflies, for example, will synchronize even in one-way interactions.

“But for humans, reciprocity comes into play in almost anything we do in pairs, be it dance, or sport, or conversation,” says Nagy.
The team also provided evidence that fish that were coupled in the timing of movements had stronger social bonds. “In other words, if you and I are coupled, we are more attuned to each other,” says Nagy.
The authors say that this finding can drastically change how we understand who influences whom in animal groups. “We used to think that in a busy group, a fish could be influenced by any other member that it can see,” says Couzin. “Now, we see that the most salient bonds could be between partners that choose to rhythmically synchronize.” More