Tech

Electron motion in atoms and molecules is of fundamental importance to many physical, biological, and chemical processes. Exploring electron dynamics within atoms and molecules is essential for understanding and manipulating these phenomena. Pump-probe spectroscopy is the conventional technique. The 1999 Nobel Prize in Chemistry provides a well-known example wherein femtosecond pumped laser pulses served to probe the atomic motion involved in chemical reactions. However, because the timescale of electron motion within atoms and molecules is on the order of attoseconds (10-18 seconds) rather than femtoseconds (10-15 seconds), attosecond pulses are required to probe electron motion. With the development of the attosecond technology, lasers with pulse durations shorter than 100 attoseconds have become available, providing opportunities for probing and manipulating electron dynamics in atoms and molecules.

Another important method for probing electron dynamics is based on strong-field tunneling ionization. In this method, a strong femtosecond laser is employed to induce tunneling ionization, a quantum mechanical phenomenon that causes electrons to tunnel through the potential barrier and escape from the atom or molecule. This process provides photoelectron-encoded information about ultrafast electron dynamics. Based on the relationship between the ionization time and the final momentum of the tunneling ionized photoelectron, electron dynamics can be observed with attosecond-scale resolution.

The relationship between ionization time and the final momentum of the tunneling photoelectron has been theoretically established in terms of a "quantum orbit" model and the accuracy of the relationship has been verified experimentally. But which quantum orbits contribute to the photoelectron yield in strong-field tunneling ionization has remained a mystery, as well as how different orbits correspond differently to momentum and ionization times. So, identifying the quantum orbits is vital to the study of ultrafast dynamic processes using tunneling ionization.

As reported in Advanced Photonics, researchers at Huazhong University of Science and Technology (HUST) proposed a scheme to identify and weigh the quantum orbits in strong-field tunneling ionization. In their scheme, a second harmonic (SH) frequency is introduced to perturb the tunneling ionization process. The perturbation SH is much weaker than the fundamental field, so it does not change the final momentum of the electron that is tunneling toward ionization. However, it can significantly alter the photoelectron yield, due to the highly nonlinear nature of tunneling ionization. Because of different ionization times, different quantum orbitals have different responses to the intervening SH field. By changing the phase of the SH field relative to the fundamental driving field and monitoring the responses of the photoelectron yield, the quantum orbits of tunneling ionized electrons can be accurately identified. Based on this scheme, the mysteries of the so-called "long" and "short" quantum orbits in strong-field tunneling ionization can be resolved, and their relative contribution to the photoelectron yield at each momentum is able to be accurately weighted. This is a very important development for the application of strong-field tunneling ionization as a method of photoelectron spectroscopy.

A collaborative team effort led by HUST graduate students Jia Tan, under the supervision of Professor Yueming Zhou, along with Shengliang Xu and Xu Han, under the supervision of Professor Qingbin Zhang, the study indicates that the hologram generated by the multi-orbit contribution from the photoelectronic spectrum can provide valuable information regarding the phase of the tunneled electron. Its wave packet encodes rich information about atomic and molecular electron dynamics. According to Peixiang Lu, HUST professor, vice director of the Wuhan National Laboratory for Optoelectronics, and senior author of the study, "Attosecond temporal and subangstrom spatial resolution measurement of electron dynamics is made possible by this new scheme for resolving and weighing quantum orbits."

For decades, researchers have been working toward mitigating excess atmospheric carbon dioxide (CO2) emissions. One promising approach captures atmospheric CO2 and then, through CO2 electrolysis, converts it into value-added chemicals and intermediates--like ethanol, ethylene, and other useful chemicals. While significant research has been devoted to improving the rate and selectivity of CO2 electrolysis, reducing the energy consumption of this high-power process has been underexplored.

In ACS Energy Letters, researchers from the University of Illinois Urbana-Champaign report a new opportunity to use magnetism to reduce the energy required for CO2 electrolysis by up to 60% in a flow electrolyzer.

In a typical CO2 flow electrolyzer, electricity is supplied to drive the reactions at the cathode (where carbon dioxide is reduced into useful byproducts) and the anode (where water is oxidized, producing oxygen).

Most studies have focused on making the reduction reaction at the cathode more efficient at higher rates; however, this process requires little energy compared to the oxidation reaction on the anode--which often accounts for more than 80% of the energy required for CO2 electrolysis, and therefore, offers the most room for improvement.

"The answer was staring us right in the face--of course, the trick is to reduce the energy consumption at the anode," said first-author Saket S. Bhargava, a graduate student in chemical and biomolecular engineering at Illinois. "We decided that if oxygen evolution is the problem, why not use a magnetic field at the oxygen evolving electrode and see what happens to the entire system."

They used a magnetic field at the anode to achieve energy savings ranging from 7% to 64% by enhancing mass transport to/from the electrode. They also swapped the traditional iridium catalyst--a precious metal--with a nickel-iron catalyst comprised of abundant elements.

"Our ultimate goal is to transform carbon dioxide back into carbon-based chemicals," said lead author Paul Kenis, a chemical and biomolecular engineering professor and department head at Illinois. "With this study, we have demonstrated how further to reduce the significant energy requirements for CO2 electrolysis, hopefully making this process more viable for adoption by industry."

New Brunswick, N.J. (June 28, 2021) - Rutgers researchers have developed a machine learning model using a physics-based simulator and real-world meteorological data to better predict offshore wind power.

The findings appear in the journal Applied Energy.

Offshore wind is rapidly maturing into a major source of renewable energy worldwide and is projected to grow by 13% in the next two decades and 15-fold by 2040 to become a $1 trillion industry, matching capital spending on gas- and coal-fired power generation. In the United States, for instance, New York and New Jersey recently awarded two offshore wind energy contracts to help achieve their targets of renewable energy integration.

"We're entering a new age of the offshore wind energy revolution," said senior author Ruo-Qian (Roger) Wang, an assistant professor in the Department of Civil and Environmental Engineering at Rutgers University-New Brunswick. "The key to support this growth is to develop reliable tools to assess and better predict offshore wind turbine performance in order to improve project planning and support operations and maintenance. The 2019 Hornsea offshore wind farm blackout in England and 2021 Texas power crisis illustrate the urgent need to develop powerful models to estimate and predict the environmental uncertainty of wind power generation."

Power curve, or the relationship that governs the conversion of weather variables experienced by a wind turbine into electric power, is widely used in the wind industry to estimate power output for planning and operational purposes. But current methods for power curve estimation have limitations, including relying mostly on wind speed and ignoring other environmental factors, and largely overlooking the complex marine environment in which offshore turbines operate.

In their study, the Rutgers researchers designed a sensitivity analysis framework to reveal and predict the major factors contributing to the environmental uncertainty of offshore wind power generation. Driving this sensitivity analysis is a machine learning model, which fuses the outputs from a physics-based simulator with real-world meteorological data collected from a set of buoys deployed off of New Jersey. The buoys are located near at least three future offshore wind projects, which cumulatively are expected to add about 2.8 gigawatts to the U.S. offshore wind capacity by 2024.

"To the best of our knowledge, the proposed modeling framework is the first to investigate the impact of up to seven environmental variables, including wind- and wave-related factors, on offshore wind power generation," Aziz Ezzat, a co-author and assistant professor of Industrial and Systems Engineering at Rutgers said. "The framework investigates the effect of the variations in the offshore environment on the performance of the state-of-the-art 15 megawatt offshore turbine design, which is envisioned to be installed off of New Jersey and other U.S. states in the near future."

The team's analysis revealed that waves play an important, if not the most important, role in predicting the second moment of wind power, i.e., its variation around the mean generation level. The researchers also found that integrating several environmental variables can significantly improve predicting power output with high accuracy.

"Tested on real-world data from the New York and New Jersey sites, our analysis framework can improve accuracy by up to 91% over the traditional industrial standard for wind power estimation, which relies on wind speed as the sole environmental input," Wang said. "The significantly higher accuracy of our multi-input power estimation model calls upon the research community and practitioners in the offshore wind industry to shift their focus towards multi-input power estimation/prediction modeling tools, especially in complex marine environments."

[BRIDGEWATER, NJ; June 29, 2021] The American Association of Feline Practitioners (AAFP) has released the updated 2021 AAFP Feline Senior Care Guidelines to be published in the July issue of the Journal of Feline Medicine and Surgery. This update provides emerging advances in feline medicine with respect to the aging cat. The Task Force of experts provides a thorough current review in feline medicine that emphasizes the individual senior patient.

As defined in the 2021 AAHA/AAFP Feline Life Stage Guidelines, cats over 10 years of age are considered to be 'senior.' Understanding the changing needs of each individual senior cat is critical for both veterinary professionals and cat owners. "Veterinary professionals are encouraged to use the 2021 AAFP Feline Senior Care Guidelines to enhance their assessment and treatment of age-associated medical conditions and to provide guidance to clients so they are included in their cat's health care team," stated Task Force Co-chair, Hazel Carney, DVM, MS, DABVP (Canine/Feline).

The Guidelines address the importance of regular veterinary visits which includes a minimum of every six months for senior cats 10 to 15 years old in order to best track and manage health-related issues and detect disease early. Healthy senior cats over the age of 15 should be examined every four months. Cats with chronic health issues may need to be seen even more frequently depending on the severity of illness. "The newly emerging concept of frailty is introduced in these Guidelines and how practitioners can incorporate this into the senior cat assessment. They also detail common issues in aging cats including pain management, nutrition and weight management, diseases and conditions, quality of life, and end of life decisions," said Michael Ray, DVM, Task Force Co-chair.

Discussion is included on how quality of life (QOL) and health-related quality of life (HRQOL) impacts the aging cat, and emphasizes veterinarians and cat owners partnering to make well-informed decisions for the individual senior cat. The Task Force also recognizes the impact caring for an aging cat has on the cat owner. Veterinarians are asked to consider four budgets of care when making treatment plans: financial, time, emotional, and physical. The weight of each of these budgets will vary for each cat owner and it is important to recognize this when having decision-making discussions.

Atomic nuclei contain enormous energy that can be extracted through their fission mechanism, for example, as a result of the radioactive decay of uranium or plutonium nuclei. Likewise, a quantum of light of several electron-volts (2.4 eV in a laser pointer with a green beam) has colossal energy. If all photons were absorbed by matter, then its temperature could reach several thousand degrees. However, in practice this does not happen. The reason is the weak light-matter interaction due to the fact that the wavelength of light (500 nm) is a thousand times larger than the size of an emitting / absorbing atom (0.5 nm). It is this physical mechanism that prevents the destruction of matter when illuminated. The efficiency of light absorption increases with the decreasing wavelength and the increasing imaginary part of the dielectric constant of the substance. When metal structures are illuminated with light of a certain wavelength, free electrons can oscillate coherently. Such oscillations of the charge density in metals are called plasmon resonances, which depend not only on the wavelength of the incident light, but the chemical nature of the metal, its size and shape as well. Due to plasmon resonance, the electric field near a metal nanoparticle can be enhanced by tens and hundreds of times. This means that such nanostructures function as optical nanoantennas that enhance the light-matter interaction. Nanoantennas are widely used in nanosensor technologies, which have found applications in materials science, nanoelectronics, and biomedicine. In the plasmon resonance regime, the density of electromagnetic energy inside the metal nanostructure increases strongly and this inevitably leads to giant optical heating from tens to several hundred degrees. For example, upon illuminating a gold spherical nanoparticle with a diameter of 50 nm with 532 nm laser light and the intensity of 20 MW/cm2, such nanostructure will melt. The field of photonics focusing on plasmon-assisted optical heating is called thermoplasmonics.

This paper proposes the concept of a plasmonic metasurface consisting of an array of square refractory nanoantennas on a silicon substrate. Titanium nitride (TiN) with the melting point of 2950 °C was used as a material for the nanoantennas. The optical heating was controlled by varying the pump power. However, the maximum temperature is limited by the size and shape of the nanoantenna. Upon changing in the size and shape, the plasmon resonance is spectrally shifted and, therefore, it is necessary to additionally tune the wavelength of the incident radiation. The publication develops an alternative way to control temperature through designing a silicon wafer by using focused ion beam etching. As a result, nanoantennas are turned to be located not on the silicon surface, but on engraved Si nanopillars, the height of which limits the maximum photoheating temperature. This method is capable of creating a controlled non-uniform temperature profile on the surface. The proposed thermoplasmonic heater was used to detect the local glass transition temperature of an amorphous polymer by scanning a focused laser beam over its surface. To test this method, the authors used an 100 nm thick film of polymethyl methacrylate.

The thermoplasmonic heater, for the first time, has provided the possibility of local sensing the glass transitions of amorphous polymers with nanometer spatial resolution. This method opens unique opportunities for studying the physicochemical properties of spatially inhomogeneous polymer films, multicomponent polymer blends, liquid crystals, and 3D spatially confined polymer nanostructures (polymer dots). It is important to emphasize that this method can be used to detect first-order phase transitions. The study of the local physicochemical properties of nanostructured polymers is an important task for the development of the element base (microfluidic channels, gates, etc.) of labs on a chip.

In the near future, the plan is to use the thermoplasmonic heater to study biological responses on single neuronal cells. An important development of the technology is subwavelength thermal microscopy, which makes it possible to visualize nanoobjects. This technology will be used to create a cognitive metasurface based on plasmon multiplexing, capable of autonomously performing simple calculations. In addition, such a local heater can be used to write/read information beyond the diffraction limit of light. Great hopes are pinned on the development of an all-optical ultrafast calorimetry method that allows not only studying kinetic processes in polymers and liquid crystals, but also creating new highly nonequilibrium phase states of nanomaterials.

As our society and transportation systems become increasingly electrified, scientists worldwide are seeking more efficient and higher capacity storage systems. Researchers at KAUST have made an important contribution by modifying lithium-sulfur (Li-S) batteries to suppress a problem known as polysulfide shuttling.

"The bottleneck in the utilization of renewable energy, especially in transportation, is the need for high-density batteries," says Eman Alhajji, Ph.D. student and first author of the research paper.

Li-S batteries have several potential advantages over the most commonly used types of batteries. They have a higher theoretical energy storage capacity and sulfur is a nontoxic element readily available in nature. Sulfur is also a waste product of the petrochemical industry, so it could be obtained relatively cheaply while increasing the sustainability of another industry.

Polysulfide shuttling involves the movement of sulfur-containing intermediates between the cathode and anode during the battery's chemical processes. This seriously degrades the capacity and recharging ability of the Li-S battery technologies that have been explored to date.

The KAUST team's solution is based on a layer of graphene. They make this by subjecting a polyimide polymer to laser energy in a process called laser scribing, creating a suitably structured porous material. A key feature is that the material is hierarchically porous in three dimensions, meaning it has an array of pores of different sizes. Nano-sized carbon particles are then added and taken up by the pores to form the final product.

Alhajji and her colleagues found that placing a thin layer of this material between the cathode and anode of an Li-S battery significantly suppresses the polysulfide shuttling.

"Making this freestanding interlayer just a few micrometers thick was a challenge," says Alhajji, adding, "It was fun to roll it like playdough, but then I had to handle it in a very gentle manner, especially during battery assembly."

Until now, most options proposed to solve the polysulfide shuttling problem have suffered from limitations that make them unsuitable for large-scale commercial application. In contrast, the laser-scribed graphene developed at KAUST is produced by a method that the researchers describe as "scalable and straightforward."

Alhajji won a 2021 Materials Research Society Best Poster Award based on her idea for suppressing the shuttling. "This is a really challenging competition," says Alhajji's supervisor Husam Alshareef, adding, "Only a handful of students from the Materials Science & Engineering program at KAUST have won this award."

What if electricity could be squeezed out of something? It turns out some materials have this property. Piezoelectricity is the electric charge that accumulates in certain solids when mechanical stress is applied on them. Piezoelectric materials, like bismuth ferrite thin films, when grown on a single lanthanum aluminate substrate give rise to highly strained epitaxial thin films that exhibit excellent electromechanical and ferroelectric properties. In bismuth ferrite thin films "doped" or polluted with lanthanum (BLFOs), piezoelectricity is attributed to the presence of "mixed-phase structures" with stripe patterns.

The formation of stripe patterns and controlling the mixed-phase structures of BLFO have been the focus of many studies over the years. But due to the ultrafast nature of phase transitions, the formation of energetically "favorable" phases under applied electric field and the origin of large electrochemical response has not been sufficiently explored. Many scientists engaged in research on BLFO are currently plagued by the question, what does the presence of an S-polymorph, an intermediate phase, do to the properties of the material?

Researchers at the Gwangju Institute of Science and Technology led by Prof. Ji Young Jo embarked on a journey to investigate the phase transformation dynamics of BLFO epitaxial thin films with the help of time-resolved X-ray microdiffraction. "We chose this technique because it helps us understand the electric field-induced phase transformation dynamics of the piezoelectric materials in a time scale ranging from picoseconds to microseconds," explains Prof. Jo. The results of their exploration of the piezoelectric properties of BLFO films along with the identification of the mixed-phase structures and striped patterns were published in volume 7 (issue 116683) of Acta Materialia on 1 April 2021 and was made available online on 21 Jan 2021.

BLFO can be converted into monoclinic (MA, MC, tilted MC), tetragonal (T-phase), an intermediate S-phase, or mixed phases via strain engineering. The investigation into the transformation dynamics revealed that the phase change from Mc to S-phase were dependent on the polarity of the electric field applied. The study also concluded that the high piezoelectric response seen in mixed-phase BLFO films is due to the presence of S/Stilt phases.

"Understanding the role of stripe patterns and the S-phases can help us create ultrafast piezoelectric devices with a response time of sub-microseconds," concludes Prof. Jo. The findings from this study provide a new perspective on the use of strain engineering to design ultra-high piezoelectric thin films. This has far-reaching implications for the future of energy harvesting.

A FLEET theoretical study out this week has found a 'smoking gun' in the long search for the topological magnetic monopole referred to as the Berry curvature.

This discovery is a breakthrough in the search for topological effects in non-equilibrium systems .

The group, led by Dimi Culcer at UNSW, identified an unconventional Hall effect driven by an in-plane magnetic field in semiconductor hole systems, which is traced exclusively to the Berry curvature.

(Conversely, the ordinary Hall effect and anomalous Hall effect both require a magnetic field/magnetisation that is perpendicular to the surface.)

Enhanced topological effects would permit low-energy topological electronics viable for large-scale, room-temperature operation, and were recently included in the IEEE roadmap towards future electronics.

ISOLATING RESPONSE A BREAKTHROUGH MOMENT

"Isolating topological responses in 'regular conductors' has been a historically difficult task," says research team leader A/Prof Dimi Culcer (UNSW). "Even though these topological responses are believed to be ubiquitous in solids".

Quantized responses, such as the quantum Hall and quantum spin-Hall effects provide a clear fingerprint of topology, yet these have only been observed in one-dimensional (1D) systems and are intimately connected with the existence of edge states.

In `regular' conductors, meaning 2D and 3D systems, plenty of theoretical literature exists predicting topological contributions to e.g. the anomalous Hall effect, but these have never been observed unambiguously in a transport measurement.

There are two main reasons for this: (i) spin-up and spin-down electrons usually make opposite contributions, and these nearly cancel out; (ii) whatever is left is overwhelmed by disorder.

The new FLEET paper remedies this long-standing shortcoming by identifying a two-dimensional system in which the Berry curvature, and only the Berry curvature, is responsible for the Hall signal linear in the applied in-plane magnetic field.

"Remarkably, all disorder contributions vanish: we are not aware of any other multi-dimensional system in which this is true," says lead author, UNSW PhD student James Cullen. "Its experimental measurement is accessible to any state-of-the-art laboratory worldwide, hence we expect strong interest from experimentalists."

BERRY CURVATURE, THE ANOMALOUS HALL EFFECT AND TOPOLOGICAL MATERIALS

The research team sought the tell-tale mathematical trace called 'Berry curvature', which can be understood if we think of the concept of parallel transport that appears routinely in geometry and general relativity.

"Think of a vector as an arrow that we place somewhere on the surface of a solid object," explains Dimi. "Now we move the arrow around, making sure it always points at the same angle to the surface - this is in fact like a human being walking along the surface of the Earth. We eventually bring the arrow back to the starting point after it has circled around, and we find that, in general, it points in a different direction - it has magically rotated through some angle. The size of this angle is determined by the curvature of the surface. "

In quantum mechanics, instead of vectors we have wave functions, but we can describe the dynamics using the same picture, and the curvature is called the Berry curvature.

The angle of rotation is replaced by the famous Berry phase, named after the mathematical physicist Prof Sir Michael Berry, who formulated the problem in the 1980s. Later on, building on work by Nobel laureate David Thouless, Qian Niu of UT Austin showed that the Berry curvature behaves like the coveted magnetic monopole--but not in real space, rather in momentum space, which is the space most condensed-matter physicists think in.

The Berry curvature drives topological effects in out-of-equilibrium systems because when an electric field is applied an electron is accelerated, so its momentum changes. When this happens its wave function changes slowly, in the same way that the `arrow' is rotated in parallel transport, and as a result of this gradual rotation a transverse (Hall) current is generated. The Onsager relations, which are fundamental to non-equilibrium physics, say that the Hall current does not dissipate energy. The extreme case is the quantum anomalous Hall effect (QAHE), a quantum effect key to the function of topological materials, in which edge currents can flow with effectively zero electrical resistance.

('Quantum' describes 'step' transition in the transverse (Hall) resistance-- ie, it varies in discrete steps rather than smoothly--while 'anomalous' refers to the phenomenon's occurrence in the absence of any applied magnetic field.)

Researchers seek to enhance QAHE in order to protect topological behaviour at higher temperatures, allowing for topological electronics that would be viable for room-temperature operation.

"The significant reduction in electrical resistance permitted by room temperature QAHE would allow us to significantly reduce the power consumption in electronic devices," says Dimi.

HARWELL, UK (29 June 2021) Researchers working on the Faraday Institution project on the recycling of lithium-ion batteries (ReLiB) at the Universities of Leicester and Birmingham have solved a critical challenge in the recovery of materials used in electric vehicle batteries at the end of their life, enabling their re-use in the manufacture of new batteries. The new method, which uses ultrasonic waves to separate out valuable material from the electrodes, is 100 times quicker, greener and leads to a higher purity of recovered materials relative to current separation methods.

The research has been published in Green Chemistry and the team have applied for a patent for the technique.

To ensure the environmental and economic benefits from EV batteries are fully realised, Faraday Institution researchers have been focused on the life cycle of the battery - from their first production to their re-use in secondary applications to their eventual recycling. One key stumbling block has been in materials segregation, that is how to remove and separate the critical materials - such as lithium, nickel, manganese and cobalt - from used batteries in a fast, economical and environmentally-friendly way.

The ReLiB team in Leicester and Birmingham devised a novel ultrasonic delamination technique that blasts the active materials from the electrodes leaving virgin aluminium or copper. This process proved highly effective in removing graphite and lithium nickel manganese cobalt oxides, commonly known as NMC. Materials recovered using the technique were found to have higher purity, and therefore higher value, than those recovered in conventional recycling approaches and are potentially easier to use in new electrode manufacture. The approach is fast and adapts technology in widespread use in the food preparation industry.

"For the full value of battery technologies to be captured for the UK, we must focus on the entire life cycle -- from the mining of critical materials to battery manufacture to recycling -- to create a circular economy that is both sustainable for the planet and profitable for industry," commented Professor Pam Thomas, CEO, The Faraday Institution.

"This effort to deliver commercial, societal and environment impact for the UK is showing great promise. It is imperative that academia, industry and government redouble their efforts to develop the technological, economic and legal infrastructure that would allow a UK EV battery recycling industry to become established to realise the full benefits of a decarbonised transport sector."

"This novel technique works in the same way as a dentist's ultrasonic descaler, breaking the adhesive bonds between the coating layer and the substrate," comments Professor Andrew Abbott at the University of Leicester who leads the research. "It is likely that the initial use of the technology will use production scrap from battery manufacturing facilities as the feedstock and feed recycled material straight back into the battery production line, possibly at the same site. This could be a real step change in battery recycling."

Current delamination recycling techniques use concentrated acids in a batch immersion process. The new ultrasonic technique is a continuous, feed process that uses water or dilute acids as the solvent so the technique is greener and less expensive to operate. It can delaminate 100 times more electrode material in a given time and volume than existing batch delamination techniques.

Researchers are in initial discussions with several battery manufacturers and recycling companies to place a technology demonstrator at an industrial site in 2021, with a longer-term aim to license the technology. The research team at the Universities of Leicester and Birmingham have tested the technology on the four most common battery types and find that it performs with the same efficiency in each case.

Tsukuba, Japan - As far back as the 1930s, inventors have commercialized fuel cells as a versatile source of power. Now, researchers from Japan have highlighted the impressive chemistry of an essential component of an upcoming fuel cell technology.

In a study recently published in The Journal of Physical Chemistry Letters, researchers from the University of Tsukuba have revealed successive proton transport--energy transfer--in an advanced carbon-based crystal for future fuel cells, and the chemistry that underpins this phenomenon.

Such crystals are exciting as solid electrolytes--energy transfer media--in upcoming fuel cell technologies. Solid electrolytes have advantages, such as high power efficiency and long-term stability, which some electrolytes lack. Solid electrolytes based on imidazole are common focuses of study. Researchers hypothesize that crystals of imidazolium hydrogen succinate can exhibit successive proton transport, also known as proton jumping. At present, this has not been rigorously confirmed, something the researchers at the University of Tsukuba aimed to address.

"A wide range of lab work and computer simulations are consistent with unidirectional proton transport in crystals of imidazolium hydrogen succinate," says lead and senior author of the study, Professor Yuta Hori. "Because this hypothesis requires further testing, we computed the molecular energy versus molecular geometry of our crystals, and compared our results with experimental data."

To do this, the researchers studied known crystal structures to investigate a chemical structure known as hydrogen bonds. Hydrogen dynamics on these bonds facilitate proton transport within the crystals and can be characterized experimentally by infrared spectroscopy.

"The spectroscopy results were clear," explains Hori. "We found that at 100°C, compared with 30°C, there was a shift to higher energy in a peak that pertains to proton transport."

Furthermore, the researchers' calculated peaks--those corresponding to chemical units that strongly contribute to hydrogen bonding--were consistent with the experimental data.

"We used these results to construct a model that traced how a proton is transferred from one imidazole unit to another," says Hori. "Our calculated potential energy surface provided geometric and energetic data that are consistent with proton jumping."

Fuel cells are used today to power a wide range of civil infrastructure and technologies, and typically produce few emissions. Improving the utility of fuel cells in more diverse applications, achieved in part by understanding how they work, will help minimize wasted power in the coming years.

Researchers have revealed that praying mantis (mantids) infected with parasitic hairworms are attracted to horizontally polarized light that is strongly reflected off the surface of water, which causes them to enter the water. In a world-first, these research results demonstrate that parasites can manipulate the host's specific light perception system to their advantage, causing the host to behave in an abnormal manner.

This discovery was made by an international research group consisting of Graduate student OBAYASHI Nasono, Associate Professor SAKURA Midori and Associate Professor SATO Takuya of Kobe University's Graduate School of Science, Associate Professor IWATANI Yasushi (Faculty of Science and Technology, Hirosaki University), Professor TAMOTSU Satoshi (KYOUSEI Science Center for Life and Nature, Nara Women's University) and Dr. CHIU Ming-Chung (National Changhua University of Education, Taiwan).

These research findings were published in the American scientific journal 'Current Biology' on June 21, 2021.

Main Points

The hairworm parasite lives inside the body of an insect host (such as mantids and crickets) that typically inhabits forests and grasslands. When the hairworm reaches maturity, it induces the host to enter water (including ponds and rivers), where the hairworm breeds, thus completing its life cycle.

How the hairworm causes its host to enter the water has mystified researchers for over 100 years.

A two-choice experiment conducted in a laboratory revealed that a higher percentage of mantids infected by a hairworm were attracted by horizontally polarized light (*1) compared to uninfected individuals.

In the outdoor experiment, a higher number of infected mantids entered the deep pool that strongly reflected horizontal light than the shallow pool that reflected weakly polarized light.

There is a strong possibility that hairworms induce the host to enter the water by manipulating the host's perception of horizontally polarized light.

Research Background

Normally, an animal's morphology and behavior are regulated in order to benefit the individual's survival and reproduction. However, approximately 40% of terrestrial organisms are parasites and it is said that all wild animals have at least one type of parasite. In other words, various anatomical changes and behaviors observed in wild animals could be strongly influenced by parasites. Remarkably, there are many species of parasite that can alter aspects of their host's morphology and behavior (host manipulation) for their own benefit (i.e. to increase the parasites' fitness). Parasites that manipulate their hosts are a good example of an extended phenotype (*2) and have come to fascinate many biologists.

A known phenomenon whereby the parasite manipulates the host's behavior can be seen in hairworms. Hairworms are nematomorph parasites that live inside insects such as mantids and camel crickets (referred to as the 'host'). However, hairworms reproduce in rivers and ponds, so in order to move themselves into these environments, they manipulate the host so that it jumps into the water (Figure 1). Previous research has suggested that the brightness of reflected light (light intensity) on the surface of the water attracts the host, causing it to fall in. However, aside from the surfaces of rivers and ponds, there are many other luminous environments and instances in nature, including forest openings, bright sandy habitats and grasslands reflecting sunlight or moonlight. If the host were attracted to every single occurrence of bright light in nature, then the host manipulation would fail. Therefore this behavior of entering the water cannot be sufficiently explained in terms of mere attraction to the light.

Polarized light (*3) is a type of light where the electric field of the light wave oscillates in only one direction. The light reflected off the surface of a body of water contains a lot of horizontally polarized light, and it has been shown in recent years that many arthropods use this horizontally polarized light to either seek out or avoid water.

The researchers hypothesized that host, manipulated by the hairworm, is attracted by the horizontally polarized light and enters the water.

Research Methodology and Results

To investigate this hypothesis, the researchers began by conducting laboratory experiments to see whether or not mantids (the Asian praying mantis species Hierodula patellifera, hereafter referred to as 'infected mantids') infected by a hairworm parasite (Chordodes sp.) and uninfected mantids of the same species would be attracted to horizontally polarized light. The experiments were conducted using a cylinder divided into three sections, with a polarized light section at one end and an unpolarized light section at the other end. The mantid was placed in the middle section, and its location was recorded after 10 minutes had elapsed (i.e. whether or not it had moved into the polarized or unpolarized light sections). Over the course of these two-choice tests, four different strengths of light were used (these corresponded to twilight: ~150 lux, cloudy weather: 2000 and 6000 lux, and sunny weather: 15,000 lux) to investigate whether the brightness affected the percentage of individuals attracted to the polarized light.

The results revealed that a higher percentage of infected mantids chose the polarized light compared to uninfected individuals (Figure 2). Among the polarized light choices, there was a particularly high tendency for polarized light of over 2000 lux to be chosen. Conversely, mantids did not tend to choose the polarized light section if the angle of polarization was changed to vertical, regardless of the strength of the light and their infection status. From these results, it can be concluded that mantids infected by hairworm parasites are attracted to horizontally polarized light.

Next, the research group conducted outdoor experiments to investigate whether or not infected mantids would jump into a pool reflecting strong, horizontally polarized light. The experiments were conducted in a cultivated area belonging to the Food Resources Education and Research Center, Graduate School of Agricultural Science, Kobe University. A mesh enclosure was set up containing two pools: Pool A, strongly reflecting horizontally polarized but dim light (low light intensity), and Pool B, where the surface reflection was brighter (strong light intensity) but weakly polarized (Figure 3).

The researchers released the infected mantids into a tree located in-between the two pools and observed the insects' entry into the water via video footage captured by stationary cameras.

Among the 16 infected mantids that exhibited this behavior, 14 individuals entered Pool A, which strongly reflected horizontally polarized light (Figure 3). Therefore based on the results of both the laboratory and outdoor experiments, it can be concluded that infected mantids are induced by the horizontally polarized light to jump into the water.

Another interesting discovery made by this study is that many infected mantids entered the water at around midday. In the laboratory experiments, the distance walked by mantids was measured and it was found that infected mantids walked more during noon. This presents a new possibility that the circadian rhythm of the host or the parasite may be involved in increasing both the host's attraction to horizontally polarized light and the host's level of activity, which ultimately induce water-entering behavior at a specific time of day.

Research Significance and Further Developments

In nature, animals have evolved diverse abilities to perceive the intensity, color, shade and polarization of light. These research results show, for the first time in the world, that parasites can skillfully manipulate these abilities to cause the host animal to exhibit behaviors that benefit the parasite.

This research group has recently begun investigating what kind of mechanism uninfected mantids have for perceiving horizontally polarized light. They are also trying to work out how hairworms manipulate this mechanism. Illuminating these aspects will not only enable us to understand parasitic behavioral manipulation but could also contribute towards the development of new methods for controlling animal behavior.

In a new article in Nature Communications, a research group led by Grigory Genikhovich at the University of Vienna has found that the way the main body axis of sea anemones is patterned by different intensities of β-catenin signaling is similar to that of sea urchins and vertebrates. This suggests that this axial patterning mechanism already existed about 650 million years ago.

The positioning of all anatomical structures in an embryo is determined by systems of molecular coordinates, which are called body axes. Different regulatory genes are activated at specific locations along the body axes to drive the development of all body parts in correct places.

This process is very ancient and regulated by the same molecules in mammals, sea urchins, mollusks, insects and corals. In each of these animal groups, the main body axis is regulated by the β-catenin signaling, while the BMP signaling patterns the secondary body axis.

The β-catenin signaling gives insights into primeval times

The β-catenin dependent axial patterning appears to be the most ancient system for axis regulation ever. A research group led by Grigory Genikhovich at the Department of Neurosciences and Developmental Biology tried to find out how the ancestral β-catenin dependent axial patterning worked. To do this, the group used the sea anemone Nematostella vectensis. Nematostella belongs to Cnidaria - an evolutionary sister group to Bilateria, which encompasses corals, sea anemones, and jellyfish. Bilateria include mammals, sea urchins, mollusks and insects.

The researchers tried to find out whether the mechanism of the patterning of the main body axis in the sea anemone resembled that of some Bilateria. If this were the case, it could be assumed that this mechanism was also used by the common ancestor of Cnidaria and Bilateria about 650 million years ago.

Similarities in pattern formation mechanism

The researchers found that β-catenin signaling in the sea anemone activates a number of transcription factor genes at the future oral end of the embryo. The expression areas of these genes form a regular pattern along the oral-aboral axis. This is achieved because more orally expressed β-catenin target genes repress more aborally expressed β-catenin target genes, and progressively restrict the initially global aboral identity. This regulatory logic is strikingly similar to the way some bilaterians such as sea urchins, hemichordates and vertebrates, pattern their posterior-anterior axis.

Moreover, the set of β-catenin dependent transcription factors involved in axial patterning in the sea anemone and sea urchins is nearly identical. The research group therefore concludes that the mechanism they found likely represents the ancestral mode of β-catenin-dependent axial patterning, and that the oral-aboral axis of cnidarians corresponds to the posterior-anterior axis of Bilateria.

"From this we conclude that animals, including the last cnidarian-bilaterian ancestor, already used this mechanism of axial patterning some 650 million years ago", says Grigory Genikhovich.

The electronic properties of graphene can be specifically modified by stretching the material evenly, say researchers at the University of Basel. These results open the door to the development of new types of electronic components.

Graphene consists of a single layer of carbon atoms arranged in a hexagonal lattice. The material is very flexible and has excellent electronic properties, making it attractive for numerous applications - electronic components in particular.

Researchers led by Professor Christian Schönenberger at the Swiss Nanoscience Institute and the Department of Physics at the University of Basel have now studied how the material's electronic properties can be manipulated by mechanical stretching. In order to do this, they developed a kind of rack by which they stretch the atomically thin graphene layer in a controlled manner, while measuring its electronic properties.

Sandwiches on the rack

The scientists first prepared a "sandwich" comprising a layer of graphene between two layers of boron nitride. This stack of layers, furnished with electrical contacts, was placed on a flexible substrate.

The researchers then applied a force to the center of the sandwich from below using a wedge. "This enabled us to bend the stack in a controlled way, and to elongate the entire graphene layer," explained lead author Dr. Lujun Wang.

"Stretching the graphene allowed us to specifically change the distance between the carbon atoms, and thus their binding energy," added Dr. Andreas Baumgartner, who supervised the experiment.

Altered electronic states

The researchers first calibrated the stretching of the graphene using optical methods. They then used electrical transport measurements to study how the deformation of the graphene changes the electronic energies. The measurements need to be performed at minus 269°C for the energy changes to become visible.

"The distance between the atomic nuclei directly influences the properties of the electronic states in graphene," said Baumgartner, summarizing the results. "With uniform stretching, only the electron velocity and energy can change. The energy change is essentially the 'scalar potential' predicted by theory, which we have now been able to demonstrate experimentally."

These results could lead, for example, to the development of new sensors or new types of transistors. In addition, graphene serves as a model system for other two-dimensional materials that have become an important research topic worldwide in recent years.

RUDN University chemists derived molecules that can assemble into complex structures using chlorine and bromine halogen atoms. They bind to each other as "velcro" - chlorine "sticks" to bromine, and vice versa. As a result supramolecules are assembled from individual molecules. The obtained substances will help to create supramolecules with catalytic, luminescent, conducting properties. The study is published in Mendeleev Communications.

Supramolecules are the structures made of several molecules. Individual molecules are combined, for example, by self-assembly or without external control. The resulting structure has properties that the molecules did not have individually. That is the way to create new materials, catalysts, molecular machines for drug delivery, conductors, and so on. To get a material with the specified properties, you need to choose the right starting molecules and auxiliary substances that will ensure their unification. One of the ways to control self-assembly is halogen-halogen interactions. These are the chemical bonds forming between two halogens (for example, chlorine, fluorine, bromine). RUDN University chemists have created a molecule with a halogen bond that can form supramolecules by itself or provide the required self-assembly with other substances. They will help to create substances for the chemical industry, medicine, and electronics.

"The possibility of fine control of the local molecular environment is highly desirable to access new properties for substances that function as catalysts, luminescent or conductive materials, etc. 2-4 Halogen bonding has recently emerged as useful instrument for the accurate control of the structural organization of such supramolecular materials. In this context, halogen-halogen interactions received a particular attention and were intensively explored both experimentally and theoretically", said the authors of the article.

Chemists used 7 types of hydrazones and carbon tetrachloride as starting materials for synthesis. The reaction lasted 1-3 hours at room temperature, with copper chloride as a catalyst. As a result, 7 compounds were obtained, two of them were suitable for the formation of a halogen-halogen bond between themselves or with other substances. RUDN University chemists studied them with X-ray diffraction analysis. Then the scientists built a 3D model of intramolecular interactions and confirmed their observations using topological analysis of the electron density distribution.

Thanks to the ability to form halogen-halogen bonds, new substances can control the self-assembly of molecules or form supramolecules themselves. That is because the new substances contain atoms of two halogens on two sides of the molecules -- chlorine and bromine. As a result, they can connect to each other through halogens -- chlorine combines with bromine, and vice versa. They can also form halogen-halogen bonds with other substances, thus controlling the assembly of supramolecules.

"Calculations demonstrated that highly polarizable dichlorodiazadiene unit is capable of acting as a relatively strong halogen bond donor. When the dye was decorated with halogen bond-accepting bromine atoms, formation of 3D supramolecular framework was observed", said the authors of the article.

Preschool children are sensitive to the gap between how much they know and how much there is to learn, according to a Rutgers University-New Brunswick study.

The research, published in the journal Psychological Science, found preschool children are more likely to choose to gather more information about something if they know just enough about it to find it interesting, but not too much that it becomes boring.

Researchers say this "optimal" amount of existing knowledge creates the perfect mix of uncertainty and curiosity in children and motivates them to learn more.

"There is an infinite amount of information in the real world," said lead author Jenny Wang, an assistant professor of cognitive psychology at Rutgers. "Yet despite having to learn so much in such a short amount of time, young children seem to learn happily and effectively. We wanted to understand what drives their curiosity."

The study focused on how children's knowledge level influences what information they find interesting. The findings suggest that children are not simply attracted to information by its novelty.

According to Wang, children are naturally curious but the difficult question is how to harness this natural curiosity.

"Ultimately, findings like this will help parents and educators better support children when they actively explore and learn about the world," Wang said.

In a series of experiments, Wang and her coauthors designed in-person and online storybooks to measure how much 3- to 5-year-old preschool children know about different "knowledge domains." The experiment also assessed their ability to understand and comprehend a specific topic, such as contagion, and asked how children's current knowledge level predicts their interest in learning more about it, including whether someone will get sick after playing with a sneezing friend.

"Intuitively, curiosity seems to belong to those who know the most, like scientists, and those who know the least, like babies," said Wang, who directs the Rutgers Cognition and Learning Center (CALC). "But what we found here is quite surprising: it was children in the middle who showed the most interest in learning more about contagion, compared to children who knew too little or too much."