Tag: Physics

Water electrolysis is a cornerstone of global sustainable and renewable energy systems, facilitating the production of hydrogen fuel. This clean and versatile energy carrier can be utilized in various applications, such as chemical CO₂ conversion, and electricity generation. Utilizing renewable energy sources such as solar and wind to power the electrolysis process may help reduce carbon emissions and promote the transition to a low-carbon economy.

The development of efficient and stable anode materials for the Oxygen Evolution Reaction (OER) is essential for advancing Proton Exchange Membrane (PEM) water electrolysis technology. OER is a key electrochemical reaction that generates oxygen gas (O₂) from water (H₂O) or hydroxide ions (OH⁻) during water splitting.

This seemingly simple reaction is crucial in energy conversion technologies like water electrolysis as it is hard to efficiently realize and a concurrent process to the wanted hydrogen production. Iridium (Ir)-based materials, particularly amorphous hydrous iridium oxide (am-hydr-IrO_x), are at the forefront of this research due to their high activity. However, their application is limited by high dissolution rates of the precious iridium.

A collaborative effort led by scientists from the Department of Interface Design at the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH and the Theory Department at the Fritz-Haber-Institut der Max-Planck-Gesellschaft provided now fundamental insights into the intertwined mechanisms of OER and Ir dissolution in amorphous, hydrous iridium oxides (am-hydr-IrO_x). Traditionally, the understanding of these processes has been limited by reliance on crystalline iridium oxide models. The paper is published in the journal Energy & Environmental Science.

In this joint effort, Hydrous Iridium Oxide Thin Films (HIROFs) was explored as a model system, which revealed a unique iridium suboxide species associated with high OER activity. In situ X-ray photoelectron and X-ray absorption spectroscopy at BESSY II and ALBA synchrotrons and Density Functional Theory (DFT) was employed to investigate the local electronic and geometric structures of these materials under operating conditions, leading to the introduction of a novel surface H-terminated nanosheet model.

This model better represents the short-range structure of am-hydr-IrO_x, revealing elongated Ir-O bond lengths compared to traditional crystalline models.

Moreover, Ir dissolution was identified as a spontaneous, thermodynamically driven process, already occurring at potentials lower than OER activation, while the prevalent mechanistic picture assumes degradation to be driven by rare events during OER. This discovery required the development of a new mechanistic framework to describe Ir dissolution through the formation of Ir defects.

The study also offered insights into the relationship between activity and stability of am-hydr-IrO_x by systematically analyzing the DFT-calculated OER activity across different Ir and O chemical environments.

Overall, the current research results challenge conventional perceptions of iridium dissolution and OER mechanisms, offering an alternative dual-mechanistic framework. By examining a highly active and porous catalyst with a singular hydroxylated Ir suboxide species, the study develops a nanosheet atomistic model that surpasses conventional crystal-based models.

This research not only challenges traditional understanding but also offers a new atomistic perspective on the delicate relationship between OER activity and durability of precious metal oxide catalysts. The findings are expected to be broadly applicable, potentially guiding the development of more efficient and stable anode materials for advancing PEM.

The chemicals known as PFAS are considered a severe threat to human health. Among other things, they can cause liver damage, cancer, and hormonal disorders. Researchers at the Technical University of Munich (TUM) have now developed a new, efficient method of filtering these substances out of drinking water. They rely on so-called metal-organic framework compounds, which work much better than the materials commonly used to date. Even extremely low concentrations of per- and polyfluoroalkyl substances (PFAS) in the water can still be captured.

Per- and polyfluoroalkyl substances (PFAS) are considered “forever chemicals”; they generally do not decompose on their own even after centuries and, therefore, pose a long-term threat to humans and animals. PFAS have been used in numerous products such as textiles, fire-fighting foams, and food packaging, and have thus been released into the environment. The substances can accumulate in the body via food and drinking water, and thus cause serious health issues.

The team led by Nebojša Ilić from the TUM Chair of Urban Water Systems Engineering and Prof. Soumya Mukherjee, a former Alexander von Humboldt postdoctoral researcher at the TUM Chair of Inorganic and Organometallic Chemistry during the study period and now Assistant Professor of Materials Chemistry at the University of Limerick, identified water-stable metal-organic framework compounds made of zirconium carboxylate as particularly effective PFAS filters.

The bespoke class of materials is characterized by adaptable pore sizes and surface chemistry. The materials are water-resistant and highly electrostatically charged. By specifically designing the structures and combining them with polymers, the filter capacity has been significantly improved compared to materials already in use, such as activated carbon and special resins.

Prof. Jörg Drewes, Chair of Urban Water Systems Engineering, emphasizes the great social significance of the research results, “PFAS pose a constant threat to public health. For too long, the negative effects of the chemicals, which, among other things, ensure that rain jackets are waterproof and breathable, have been underestimated. The industry has now started to rethink this, but the legacy of PFAS will continue to affect us for several generations to come.”

Researchers from the TUM School of Natural Sciences worked together with colleagues from the TUM School of Engineering and Design and simulation experts from the TUM School of Computation, Information, and Technology to develop and research the new filters.

Prof. Roland Fischer, Chair of Inorganic and Organometallic Chemistry, emphasizes, “When solving such major challenges, experts from a wide range of disciplines have to work together. You simply can’t get anywhere on your own. I am delighted that this approach has again proved its worth here.”

However, it will be some time before this new filter material is adopted at large scale in waterworks. The newly discovered principle would have to be implemented with sustainably available, inexpensive materials that are safe in every respect. This will require considerable further research and engineering solutions.

A team of scientists led by Professor Annette Beck-Sickinger from the Institute of Biochemistry at Leipzig University has made an important advance in pain relief research. They discovered that hederagenin, a naturally occurring substance found in the medicinal plant ivy, binds to the pain regulation receptor. Extracts of ivy (Hedera helix) have antispasmodic and analgesic effects in phytomedicine.

In the search for selective inhibitors of the protein neuropeptide FF receptor 1, which is relevant for human pain regulation, the researchers discovered that hederagenin is well suited for this purpose. They have now published their findings in the journal Angewandte Chemie International Edition.

Neuropeptide FF receptor 1 (NPFFR1) is a G protein-coupled receptor (GPCR) involved in the signaling of various physiological processes in the human body. In recent years, it has been discovered that this protein is mainly found in the spinal cord and in areas of the brain involved in pain perception. Blocking this receptor could help treat chronic pain. This has not been possible until now because NPFFR1 has many similar relatives.

Two scientists from Beck-Sickinger’s research group tested thousands of substances. Michael Schaefer, Professor of Pharmacology at the Faculty of Medicine, provided a screening platform for this purpose. The researchers came across the naturally occurring substance hederagenin.

They characterized the binding mode of the inhibitor in detailed in vitro studies. Computer modeling of the three-dimensional receptor-inhibitor complex by Professor Jens Meiler’s group at the Institute for Drug Discovery confirmed this insight.

“These findings make a significant contribution to understanding the activation mechanism of NPFFR1 and may facilitate the rational design of future therapeutics for chronic pain. They demonstrate the importance of basic research in translating findings into applications,” says Professor Beck-Sickinger.

A research team has proposed a new strategy for designing pure-red organic light emitting diodes (OLED) materials. These materials have achieved a milestone with electroluminescence efficiencies exceeding 43%, marking a significant step toward high-performance ultrahigh-definition OLED displays. The study was published online in the Journal of the American Chemical Society.

OLEDs have emerged as a leading technology due to their unique features such as flexibility and bright self-emission. However, the performance of red OLEDs, especially in the saturated red region, has lagged behind that of their blue and green counterparts. The development of efficient red emitters with high color purity has been a major challenge in the field.

Focusing on overcoming the challenge of red light emitters, the research team proposed a new strategy for the design of pure-red OLED materials with high luminous efficiency, excellent color purity, and long-term stability. The key innovation lies in the molecule BNTPA, which was designed to incorporate secondary electron-donating units and extend the π-skeleton within multiresonance cores. This structural modification significantly enhances intramolecular charge transfer, enabling the molecule to more efficiently handle the excitation energy.

As a result, light emission is effectively shifted into the red spectrum, while still maintaining narrowband characteristics for ensuring high color fidelity, which is a key requirement for high-definition displays. To further improve the molecular design, the team optimized the reverse inter-system crossing (RISC) process. BNTPA’s refined structure not only accelerates the RISC rate but also ensures a balanced combination of short-range and long-range charge transfer characteristics.

This balance is particularly important for improving the overall photophysical performance of the emitter, as it minimizes energy loss and improves both the luminous efficiency and stability of the OLEDs. Additionally, the integration of secondary electron-donating units stabilizes the excited states of BNTPA, reducing non-radiative decay and preventing energy loss that often occurs in red-emitting materials.

This enhancement of the molecular architecture ensures that BNTPA-based OLEDs achieve greater operational stability and longer lifetimes, making them suitable for practical, long-term use in real-world applications.

OLEDs based on BNTPA achieved a record-breaking external quantum efficiency exceeding 43%. Its CIE value is (0.657, 0.343), and aligns closely with NTSC standards (0.67, 0.33), achieving excellent color purity. These advancements are attributed to the molecule’s optimized design, which enhances energy efficiency and operational stability. This establishes BNTPA as a benchmark for next-generation high-performance red MR-TADF emitters.

This research sets a precedent for future research and practical deployment in high-definition displays and next-generation electronic devices. It also contributes to the development of energy-efficient and durable lighting systems, enabling OLED displays to meet stringent color standards.

The team was led by Prof. Cui Songlin at University of Science and Technology of China (USTC), in collaboration with Prof. Zhou Meng’s team from Beijing Information Science and Technology University (BISTU).

A research team led by Prof. Kang Yanbiao from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences has made a significant discovery in the field of environmental chemistry. They developed a novel photocatalyst named KQGZ, which can photocatalytically defluorinate polyfluoroalkyl and perfluoroalkyl substances (PFAS) at a low temperature range of 40°C–60°C. This finding has been published in Nature.

PFAS, referred to as “forever chemicals,” possess high thermal and chemical stabilities as well as hydrophobic and oleophobic properties because of the inert carbon-fluorine (C–F) bonds. As a result, they are widely used in various fields such as chemicals, electronics and medical devices.

However, the inertness of the C–F bonds also makes it difficult for PFAS to decompose through defluorination under natural environment or mild conditions. For example, pyrolysis of Teflon usually proceeds at over 500°C and toxic gases are released. The disposal of PFAS into the natural environment has led to a series of environmental and health issues.

To address the challenges, the team designed and created an organic super-photoreductant called KQGZ based on the characteristics of photoreductants’ strong reducibility under specific light conditions. As a type of photoreductant, KQGZ can be excited by absorbing light and transfer an electron from its excited state to other organic molecules.

By adding KQGZ to the reaction system and experimenting with various reaction conditions, the team achieved complete defluorination and mineralization of Teflon and small molecule PFAS at low temperatures for the first time, efficiently recycling them into inorganic fluoride salts and carbon resources.

More specifically, the study’s core experiments involved the application of KQGZ as a photocatalyst under visible light to defluorinate a range of PFASs, including polytetrafluoroethylene (PTFE), perfluorocarbons (PFCs), perfluorooctane sulfonic acid (PFOS), polyfluorooctanoic acid (PFOA), and their derivatives.

The process resulted in the formation of amorphous carbon and fluoride salts from PTFE, while oligomeric PFASs yielded a variety of carbonate, formate, oxalate, and trifluoroacetate products. This not only addresses the degradation of PFASs but also enables the recycling of fluorine in the form of inorganic fluoride salts.

A detailed mechanistic investigation was also conducted to understand the reaction behavior and product composition differences between PTFE and oligomeric PFAS. The researchers discovered that the photocatalytic reduction ability is not directly correlated with the excited oxidation potential of the photocatalyst, challenging the traditional paradigm in the field.

This insight suggests that the electron transfer ability of the photocatalyst may be related to the torsion of the carbazole ring, a finding that could guide the design of more effective photocatalysts in the future.

Finally, the study also meticulously investigated the effects of various reducing reagents, finding that most demonstrated good reactivity, with γ-terpinene and cesium formate yielding the highest results. Control experiments confirmed the indispensable role of light, photocatalyst, and reducing reagent in the defluorination process.

This study not only reports for the first time the promoting effect of highly twisted carbazole-cores on the electron transfer of super-photoreductants, but also shows that the excited oxidative potential of photoreductants is not directly related to their reduction ability, and therefore should not be the only standard for the photoreduction ability. In addition, the ability to completely defluorinate Teflon and other PFAS can serve as a standard for the reduction ability of organic reductants.

Have you ever imagined that high-density metals could be converted into an ultralight aerogel? This counterintuitive idea was presented in 2009 by Eychmüller’s group, where all-metal-made aerogels, i.e., metal aerogels (MAs), were produced by assembling metal nanoparticles in a controlled manner. Since then, these special and promising materials have been explored by global scientists, gradually forming a new field in materials science.

MAs composed of more than one metal, namely multimetallic aerogels (MMAs), have received particular attention, because MMAs feature widely tunable properties stimulated by the synergy of multiple metals. For a material structured from multiple components, the first thought might be whether this material will have attributes stemming from each constituent, or if it will feature enhanced performance because of the synergy of different constituents.

Indeed, many research articles demonstrate that MMAs are often better than single-component MAs in, for example, electrocatalysis. Better performance was primarily achieved by tuning the difference in electrical conductivity, lattice parameters and electronic structure of dissimilar metals.

I am interested in controlled synthesis because I believe the synthesis ability dictates how far a material goes. Therefore, instead of the application aspect, I am concentrating on the synthesis aspect incurred by multimetallic effects. This is the motivation of our paper published in Matter titled “Manipulating multimetallic effects: Programming size-tailored metal aerogels as self-standing electrocatalysts.”

In our study, we found that multimetallic effects concurrently impacted the sol-gel process of metals and the ligament size of the resulting MMAs.

We discovered an unconventional, gravity-driven gelation behavior of metal systems in a Science Advances paper five years ago. We found that the gelation process of metal systems is similar to a precipitation process. Driven by the high density of metals (e.g., the density of gold is ~19.3 g cm^-3), the as-formed metal aggregates eventually settle down with the lapse of time and form a monolithic gel at the vessel bottom.

If the metal aggregate is not solely made up of gold, for example, what will happen for a gold-silver bimetallic system? The incorporation of relatively low-density silver (~10.5 g cm^-3) will reduce the average density of metals and thus slow down the sedimentation process, leading to a prolonged gelation time.

This was proven by our experiments and characterizations using a variety of metal combinations (single, binary and triple metals). It not only offers a way to tune the sol-gel process but also confirms the generality of our proposed gravity-driven gelation mechanism.

The most exciting and important part is the ligament size control via multimetallic effects. The ligament size is a critical parameter for MAs, for it dictates the nano effects and thus many physicochemical properties of materials.

Historically, the ligament size is tuned by modulating the initiators or introducing ligands, which may contaminate the resulting MAs. Taking a glance at all reported MAs since 2009, one will recognize that some MAs (e.g., Au, Ag) often feature large ligament sizes while others (e.g., Pd, Pt, Ru, Rh) often feature small ligament sizes. However, almost all alloy aerogels feature small ligament sizes. Then the question arises: What happens when two metals come together?

We thoroughly studied the ligament size change by controllably introducing different types and amounts of auxiliary metals into the main metal systems (e.g., introducing nickel sources to gold sources before conducting the gelation process). We found that 1% auxiliary metals drastically reduced the ligament size by ~ 30% to 78%, which worked for Au, Ag and Cu-based aerogels.

This impressive phenomenon was rationalized by the atomic radius mismatch between the main metal and the auxiliary metal. The mismatch will retard the layer-type deposition of metal atoms. Instead, the ligament growth will follow an island-type deposition style, thus producing more branches and thinning the ligament size (see image above). Depending on the mismatch degree and the proportion of the auxiliary metal atoms, the ligament size can be well adjusted.

Finally, using the gravity-driven gelation behavior, we developed a sedimentation-based, non-destructive strategy to boost the electrocatalytic performance of MMAs. This technique avoids the sonication-led structure destruction that was suffered by previously reported MA-based electrocatalysts.

Briefly, several pieces of carbon paper were placed at the bottom of the reaction vessel, accepting the settled metal aggregates. The in-situ-generated metal aggregates will gradually sediment and enrich on the carbon paper, thus forming a CP-supported intact gel film (the Au-Pt system was used as an example).

This CP-supported intact Au-Pt gel film was directly used as the working electrode to catalyze the alcohol oxidation reaction. Because of its well-retained network, this intact metal gel manifested record-high performance for both methanol- and ethanol- oxidation reactions.

In summary, our study not only provides a fresh viewpoint on using multimetallic effects for tuning the preparation and structure of MMAs but also solves the long-lasting challenge of preparing intact metal gel-based electrocatalysts for high-performance catalysis.

This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate.

Ran Du received his B.E. in 2011 from Beijing Institute of Technology and PhD degree in 2016 from Peking University. After successive research stays at Nanyang Technological University (2016–2017), TU Dresden (2017–2019, sponsored by Humboldt fellowship), and Hong Kong University (2020–2021), he joined the Beijing Institute of Technology as a professor in 2021. His research interest lies in the creative synthesis of advanced aerogels (e.g., metal aerogels, nanocarbon aerogels, etc.) and exploring their smart applications in catalysis, environment remediation, and smart materials.

Currently employed computational methods to simulate materials and their mechanical behavior are based on molecular dynamics (MD) with atomistic force-fields. These methods provide an excellent description of the thermodynamically stable phases of materials with arbitrary chemical and microstructural complexity.

However, simulating the mechanical deformation behavior of materials at the atomistic level, or, in general, the response of a material to an external time-dependent stimulus, has been an open challenge for a long time. The main bottleneck is represented by the inevitably short time scale of integration of the equations of motion (just a few femtoseconds) that atomistic MD methods rely on. This is a necessary step in order to discretize the equations of motion that govern atomic motions and collisions, in order to solve them on a computer.

This limitation makes it impossible to simulate the dynamical deformation of materials on long time scales encountered in experiments, i.e., for deformation rates lower than ~10 to 100 gigahertz. This fundamental time-scale bridging problem is currently unsolved, and prevents the computational prediction of material mechanics in the regimes that are experimentally accessible in standard mechanical tests and rheology.

With my post-doc, Dr. Vinay Vaibhav, and with my long-time collaborator at the US Army Research Lab, Dr. Tim Sirk, I have now developed a computational framework that provides a working solution to this problem, arguably one of the biggest problems in molecular simulations of materials under deformations and external stimuli.

The key idea of our approach is that the mechanical response at the low frequencies (e.g., around the Hertz) is dominated by atomic displacements known as nonaffine displacements. A nonaffine displacement is a swerve in the trajectory of an atom, which thus deviates from the trajectory prescribed by the externally imposed deformation (akin to Epicurus’s “clinamen,” if you are familiar with Greek philosophy).

The origin of this swerve is the necessity to enforce mechanical equilibrium at every step in the deformation. In other words, at each step, the atom receives forces from its neighbor atoms, which need to be relaxed via an extra motion, the nonaffine swerve.

As my collaborators and I have come to realize over the years, implementing this description of atomic trajectories implies computing the vibrational normal modes of the system, which can be done with modern computational techniques.

This has now allowed us, in a paper published in the journal Macromolecules, to achieve a parameter-free agreement with the viscoelastic moduli of a real complex material, a crosslinked epoxy polymer glass in its amorphous solid state, at frequencies that are about 10 orders of magnitude lower than those that can be achieved by simulating the deformation process in standard molecular dynamic simulations.

The agreement with experimental data from mechanical tests is striking, considering that no adjustable parameters are involved in the comparison.

Our approach can still be refined in future work, e.g., by taking larger snapshots of the material configuration, with an increasing number of atoms, which will improve our predictions and reduce the noise from numerical fluctuations.

An exciting prospect offered by this method is that of being able to single out the atomic and molecular vibrations, and motions, that are mostly responsible for the stiffness and hardness of a given material (or, conversely, for its softness), with plenty of opportunities for the development of new materials with high-performance properties for many technological and engineering applications.

This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate.

A research group led by Professor Wei Li from the Department of Pharmacognosy, Faculty of Pharmaceutical Sciences, Toho University in collaboration with the Faculty of Pharmacy at Ankara University and Ankara Medipol University in Turkey revealed the presence of diverse daphnane diterpenoids in Daphne pontica (Thymelaeaceae).

Daphnane diterpenoids possess anticancer, anti-HIV, and analgesic properties, suggesting that D. pontica is a potential novel plant resource for drug discovery. This research was published in the journal Phytochemical Analysis on November 7, 2024.

Key points

• LC-MS/MS analysis revealed the presence of daphnane diterpenoids with diverse chemical structures in Daphne pontica.
• Among the daphnane diterpenoids detected, six compounds were postulated to be previously unreported compounds based on MS/MS fragmentation elucidation.
• A comparative analysis of diterpenoids in the stems, leaves, and fruits of D. pontica demonstrated that stems containing the most abundant daphnane diterpenoids.
• This study highlighted the potential of D. pontica as a resource for novel drug development by further exploring the biological activities of daphnane diterpenoids.

The Thymelaeaceae family comprises 53 genera and over 800 species distributed all over the world, excluding in the arctic zone. Plants of this family are characterized by the presence of diterpenoids with potent biological activities, including anticancer, anti-HIV, and analgesic effects.

Daphne pontica, an evergreen shrub of the genus Daphne, is native to northern Turkey, southeastern Bulgaria, northern Iran, and the Caucasus region. In traditional Turkish and Iranian medicine, it has been used as an anti-diarrheal and pain-relieving agent.

In this study, the research group analyzed the stems, leaves, and fruits of D. pontica using ultra-high-performance liquid chromatography coupled with a Q-Exactive hybrid quadrupole Orbitrap mass spectrometer (UHPLC-Q-Exactive-Orbitrap MS) and identified 33 daphnane diterpenoids in the three parts.

This comprehensive analysis represents the first report of daphnane diterpenoids being thoroughly identified in D. pontica, including newly discovered compounds that have not been previously isolated from other plants.

A team of scientists has created a new shape-changing polymer that could transform how future soft materials are constructed. Made using a material called a liquid crystalline elastomer (LCE), a soft rubber-like material that can be stimulated by external forces like light or heat, the polymer is so versatile that it can move in several directions.

Its behavior, which resembles the movements of animals in nature, includes being able to twist, tilt left and right, shrink and expand, said Xiaoguang Wang, co-author of the study and an assistant professor in chemical and biomolecular engineering at The Ohio State University.

“Liquid crystals are materials that have very unique characteristics and properties that other materials cannot normally achieve,” said Wang. “They’re fascinating to work with.”

This new polymer’s ability to change shapes could make it useful for creating soft robots or artificial muscles, among other high-tech devices in medicine and other fields.

Today, liquid crystals are most often used in TVs and cell phone displays, but these materials often degrade over time. But with the expansion of LEDs, many researchers are focused on developing new applications for liquid crystals.

Unlike conventional materials that can only bend in one direction or require multiple components to create intricate shapes, this team’s polymer is a single component that can twist in two directions. This property is tied to how the material is exposed to temperature changes to control the molecular phases of the polymer, said Wang.

“Liquid crystals have orientational order, meaning they can self-align,” he said. “When we heat the LCE, they transition into different phases causing a shift in their structure and properties.”

This means that molecules, tiny building blocks of matter, that were once fixed in place can be directed to rearrange in ways that allow for greater flexibility. This aspect may also make the material easier to manufacture, said Wang.

The study was recently published in the journal Science.

If scaled up, the polymer in this study could potentially advance several scientific fields and technologies, including controlled drug delivery systems, biosensor devices and as an aid in complex locomotion maneuvers for next-generation soft robots.

One of the study’s most important findings reveals the three phases that the material goes through as its temperature changes, said Alan Weible, co-author of the study and a graduate fellow in chemical and biomolecular engineering at Ohio State. Throughout these phases, molecules shift and self-assemble into different configurations.

“These phases are one of the key factors we optimized to allow the material ambidirectional shape deformability,” he said. In terms of size, the study further suggests that the material can be scaled up or down to adapt to nearly any need.

“Our paper opens a new direction for people to start synthesizing other multiphase materials,” said Wang.

Researchers note that with future computational advances, their polymer could eventually be a useful tool for dealing with delicate situations, like those that require the precise design of artificial muscles and joints or upgrading soft nanorobots needed for complex surgeries.

“In the next few years, we plan to develop new applications and hopefully break into the biomedical field,” said Weible. “There’s a lot more we can explore based on these results.”

Other co-authors include Yuxing Yao, Shucong Li, Atalaya Milan Wilborn, Friedrich Stricker, Joanna Aizenberg, Baptiste Lemaire, Robert K. A. Bennett, Tung Chun Cheung and Alison Grinthal from Harvard University; Foteini Trigka and Michael M. Lerch from the University of Groningen; Guillaume Freychet, Mikhail Zhernenkov and Patryk Wasik from Brookhaven National Laboratory; and Boris Kozinsky from Bosch Research.