Advanced Materials WINTER 2021

Spread knowledge Editorial

Spread knowledge

A very special year has passed. Covid-19 gave the framework for our professional and private life. This was not always easy, it was not always nice, but it was no stop sign to research. Research has actually gained a lot of visibility. European leaders decided to tackle Covid-19 by listening to scientific advisors, use evidence-based scenario’s, see hypothesis been proven wrong or right and reacting to it. The teams working on Covid-vaccines have made enormous leaps in a short time to provide new, safe vaccines that may help to recover society. This new focus on scientific advice and research solving a problem, may be an enormous opportunity to build on for all scientific disciplines. Science is not a hobby; Colophon it is not just an opinion. Science is ideally balancing existing knowledge, new results, interpretation and Editors critical discussion to a sound consensus. It provides Jan Peter Birkner solutions to complex problems, some of which overseen by the public, some of which at the center of interest. Wherever in this spectrum research on Advanced Photography Materials is, investing in it may be essential already Sylvia Germes in the near future. And spreading the knowledge on what is going on Design in our labs may create ground for the next good to Mónica Espinoza happen. Therefore: stay safe, stay curious, enjoy our stories here, and keep telling your story. Cangahuala

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Contact Coordinating Office Nijenborgh 4 Eric Heeres 9747 AG Groningen Director for the Engineering and T: +31 50 363 4922 Technology Institute Groningen W: www.rug.nl/zernike E: [email protected]

Adri Minnaard Director of the Stratingh Institute for Chemistry

Caspar van der Wal Scientific director Zernike Institute for Advanced Materials

2 ADVANCED MATERIALS | WINTER 2021 In this issue

AI reduces computational time required to study fate of molecules exposed to light 4

Combining incipient ferroelectrics and graphene leads to new insights into memristive devices 6

Turning heat into power with efficient organic thermoelectric material 8

Spin-orbit coupling leads to stable spins in color centers in materials 10

New High Speed AFM results featured as Spotlight in JACS 12

Polymer scientists cooperate with industry to create smart materials 14

X-rays reveal in situ crystal growth of lead-free perovskite solar panel materials 16

Spider Silk inspires a new class of synthetic ion-conducting polymers for future energy applications 18

Detailed model important step towards understanding Huntington’s 20

Scientists create coatings from nature 21

Elisabetta Chicca new professor Bio-inspired Circuits & Systems “If we cannot build neural networks, we can’t understand them properly” 22

Simple explanation suffices for conduction in nickelates 24

New assistant professor in our team - Jagoda Sławińska “I think theorists can work more closely with experimentalists” 26

Finding the missing mirror in spintronic nanodevices 28

New pathways with Skyrmion bubbles 29

New model helps to describe defects and errors in quantum computers 30

Transporting energy through a single molecular nanowire 32

Newsflash 33

CogniGron is two years along the path towards ‘human’ computers 34

Virus assembly has been filmed 37 In Focus AI reduces computational time required to study fate of molecules exposed to light by Rene Fransen (ScienceLinX)

Light-induced processes are critical in transformative technologies such as solar energy harvesting, as well as in photomedicine and photoresponsive materials. Theoretical studies of the dynamics of photoinduced processes require numerous electronic structure calculations, which are computationally expensive. Scientists from the University of Groningen developed machine learning-based algorithms, which reduce these computations significantly. The Open Source software package that they developed, PySurf, was presented in a paper in the Journal of Chemical Theory and Computation on 24 November.

How do molecules behave when for medium-sized molecules, they are exposed to light? typical chromophores have around Knowledge of this process is not thirty heavy atoms.’ Including the only central to crucial processes Our software, influence of the environment at in nature, such as photosynthesis quantum mechanical level on such and vitamin D production, but it is therefore, a system is practically impossible. also critical for the rational design requires several of new molecules with specific ‘Current software searches photoresponsive properties. orders of the entire conformational magnitude less space, but we use machine Machine learning learning to exclude parts of Yet, despite great advances in computational this conformational space hardware and computational search, making it a very smart methods, calculations of the time than existing search,’ Faraji explains. ‘Our interaction between light and direct dynamics software, therefore, requires molecules is still a challenge, several orders of magnitude explains Shirin Faraji, Associate software less computational time than Professor in Theoretical Chemistry, existing direct dynamics software.’ the lead author of the paper. ‘The In the paper, the developers high-level electronic structure report the photodynamics of

calculations are already very costly two benchmark molecules, SO2

4 ADVANCED MATERIALS | WINTER 2021 In Focus

Representation of machine learning electronic-structure based excited states of a molecule responding to light Illustration: Faraji Lab. and pyrazine, and show that the manual, and Faraji’s team their results are comparable will provide support for users. to those obtained using simulations that are based First release entirely on quantum dynamics. The PySurf software is the result of a project funded by a personal Algorithm grant to Faraji from the Dutch Furthermore, the software Research Council (NWO) Vidi package was developed from programme. Faraji: ‘We are A PhD student scratch and is easy to adapt for only a year and a half into this specific purposes, for example five-year project. So, the current could easily dig by using plug-in and workflow version is just the first release. into the code engines. Faraji: ‘A PhD student We continue to work on the could easily dig into the code program to optimize it and to and develop and develop a specific algorithm, create a user-friendly interface.’ for example a new neural a specific network-based algorithm.’ Reference: Maximilian F. S. J. algorithm, for Menger, Johannes Ehrmaier, Faraji contributed code to and Shirin Faraji: PySurf: example a new several software packages, A Framework for Database neural network- most notably Q-Chem, one of Accelerated Direct Dynamics. the world’s leading quantum J. Chem. Theory Comput. based algorithm. chemistry software programs, online 24 November 2020. and is currently a member of the Q-Chem Board of Directors. This work is part of the The new PySurf package will Innovational Research Incentives interface with Q-Chem, but also Scheme Vidi 2017 with project with other electronic structure number 016.Vidi.189.044, software. PySurf is Open Source, which is (partly) financed by the which means that it is available Dutch Research Council (NWO). as a free download together with

UNIVERSITY OF GRONINGEN 5 In Focus Combining incipient ferroelectrics and graphene leads to new insights into memristive devices by Rene Fransen (ScienceLinX)

Transistors can have just two values: 0 or 1. Our brains process information via neurons, which are more complicated: they can have any intermediate value, based on the memory of the input they received in the long-term or short-term past. Scientists are trying to build transistors with a similar type memory, called memristors. One interesting material for creating memristive devices is strontium titanium oxide. Scientists from the University of Groningen discovered how this material can change its resistance based on changes in the number of electrons or the accumulation of defects created by the absence of oxygen atoms in the crystal structure. These insights, derived by combining strontium titanium oxide with the 2D material graphene, could lead to the creation of memristors responding at different timescales, corresponding to short-term and long-term memory.

Scientists are working on new a great many of these binary materials to create neuromorphic systems, computers can perform computers, with a design based calculations very rapidly. However, on the human brain. A crucial in other respects, computers are component is a memristive device, not very efficient. Our brain uses ... the the resistance of which depends less energy for recognizing faces on the history of the device – or performing other complex tasks combination with just like the response of our than a standard microprocessor. graphene opens neurons depends on previous That is because our brain is made input. Materials scientists from the up of neurons that can have many up a new path University of Groningen analysed values other than 0 and 1 and to memristive the behaviour of strontium because the neurons’ output titanium oxide, a platform material depends on previous input. heterostructures for memristor research and used the 2D material graphene to probe Oxygen vacancies combining it. On 11 November 2020, the To create memristors, switches ferroelectric results were published in the with a memory of past events, journal ACS Applied Materials strontium titanium oxide (STO) materials and 2D and Interfaces. is often used. This material is materials. a perovskite, whose crystal Computers are giant calculators, structure depends on temperature, full of switches that have a and can become an incipient value of either 0 or 1. Using ferroelectric at low temperatures.

6 ADVANCED MATERIALS | WINTER 2021 In Focus

studies carried out at Uppsala University, shows that oxygen vacancies near the surface of the STO are responsible.

Memory Banerjee: ‘The phase transitions below 105 Kelvin stretch the crystal structure, creating dipoles. We show that oxygen vacancies accumulate at the domain walls and that these walls offer the channel for the movement of oxygen vacancies. These channels are responsible for memristive behaviour in STO.’ Accumulation of oxygen vacancy channels in the crystal structure of STO explains the shift in the position of the minimum conductivity.

Chen also carried out another The combination with graphene opens up a new path to memristive experiment: ‘We kept the STO gate heterostructures combining ferroelectric materials and 2D materials. voltage at -80 V and measured Illustration: Banerjee lab the resistance in the graphene for almost half an hour. In this The ferroelectric behaviour is lost of STO arise from imperfections period, we observed a change above 105 Kelvin. The domains in the crystal structure. We found in resistance, indicating a shift and domain walls that accompany that combining them leads to new from hole to electron conductivity.’ these phase transitions are the insights and possibilities.’ Much This effect is primarily caused subject of active research. Yet, of this work was carried out by by the accumulation of oxygen it is still not entirely clear why Banerjee’s PhD student Si Chen. vacancies at the STO surface. the material behaves the way She placed graphene strips on top it does. ‘It is in a league of its of a flake of STO and measured All in all, the experiments own,’ says Tamalika Banerjee, the conductivity at different show that the properties of Professor of Spintronics of temperatures by sweeping a the combined STO/graphene Functional Materials at the Zernike gate voltage between positive material change through the Institute for Advanced Materials, and negative values. ‘When there movement of both electrons University of Groningen. is an excess of either electrons or and ions, each at different time the positive holes, created by the scales. Banerjee: ‘By harvesting The oxygen atoms in the crystal gate voltage, graphene becomes one or the other, we can use appear to be key to its behaviour. conductive,’ Chen explains. ‘But the different response times to ‘Oxygen vacancies can move at the point where there are very create memristive effects, which through the crystal and these small amounts of electrons and can be compared to short-term or defects are important,’ says holes, the Dirac point, conductivity long-term memory effects.’ The Banerjee. ‘Furthermore, domain is limited.’ study creates new insights into walls are present in the material the behaviour of STO memristors. and these move when a voltage In normal circumstances, the ‘And the combination with is applied to it.’ Numerous studies minimum conductivity position graphene opens up a new path have sought to find out how this does not change with the to memristive heterostructures happens, but looking inside this sweeping direction of the gate combining ferroelectric materials material is complicated. However, voltage. However, in the graphene and 2D materials.’ Banerjee’s team succeeded in strips on top of STO, there is using another material that is in a a large separation between the Reference: Si Chen, Xin Chen, league of its own: graphene, the minimum conductivity positions Elisabeth A. Duijnstee, Biplab two-dimensional carbon sheet. for the forward sweep and the Sanyal, and Tamalika Banerjee: backward sweep. The effect is Unveiling Temperature-Induced Conductivity very clear at 4 Kelvin, but less Structural Domains and Movement ‘The properties of graphene pronounced at 105 Kelvin or of Oxygen Vacancies in SrTiO3 are defined by its purity,’ says at 150 Kelvin. Analysis of the with Graphene. ACS Appl. Mater. Banerjee, ‘whereas the properties results, along with theoretical Interfaces, 11 November 2020

UNIVERSITY OF GRONINGEN 7 In Focus Turning heat into power with efficient organic thermoelectric material by Rene Fransen (ScienceLinX)

Thermoelectric materials use a temperature difference between both sides of the material to create an electric current. Inorganic thermoelectric materials are already quite efficient, but they contain toxic or rare elements and are often brittle, which makes them unsuitable for everyday applications. By contrast, organic thermoelectric materials are safe to use, but their efficiency in converting a temperature difference into a current is not very good. A team of scientists led by Jan Anton Koster, Professor of Semiconductor Physics at the University of Groningen, has now created a much more efficient organic thermoelectric material that is made from buckyballs with organic side chains. Their flexible material could be used to power wearable electronics.

Thermoelectric materials can turn a temperature difference into electricity. Organic thermoelectric materials could be used to power wearable electronics or sensors; however, the power output is still very low. An international team led by Jan Anton Koster, Professor of Semiconductor Physics at the University of Groningen, has now produced an n-type organic semiconductor with superior properties that brings these applications a big step closer. Their results were published in the journal Nature Communications on 10 November.

The thermoelectric generator have their own problems. The semiconductors is that they is the only human-made power optimal thermoelectric material usually have a low electrical source outside our solar system: is a phonon glass, which has a conductivity.’ both Voyager space probes, which very low thermal conductivity were launched in 1977 and are (so that it can maintain a Nevertheless, over a decade of now in interstellar space, are temperature difference) and experience in developing organic powered by generators that also an electron crystal with photovoltaic materials at the convert heat (in this case, high electrical conductivity (to University of Groningen has led provided by a radioactive source) transport the generated current). the team on a path to a better into an electric current. ‘The great Koster: ‘The problem with organic organic thermoelectric material. thing about such generators is They focused their attention on that they are solid-state devices, an n-type semiconductor, which without any moving parts,’ carries negative charge. For a explains Koster. thermoelectric generator, both The problem n-type and p-type (carrying Conductivity positive charge) semiconductors However, the inorganic with organic are needed, although the efficiency thermoelectric material used semiconductors of organic p-type semiconductors in the Voyager’s generators is is already quite good. not suitable for more mundane is that they applications. These inorganic Buckyballs materials contain toxic or very usually have a The team used fullerenes rare elements. Furthermore, low electrical (buckyballs, made up of sixty they are usually rigid and carbon atoms) with a double- brittle. ‘That is why interest conductivity triethylene glycol-type side chain in organic thermoelectric added to them. To increase materials is increasing,’ says the electrical conductivity, Koster. Yet, these materials an n-dopant was added. ‘The

8 ADVANCED MATERIALS | WINTER 2021 In Focus

The chemical structure of the fullerene derivative used in our work improves the ordering of the molecules as shown (right) in the snapshots of the molecular packing. By using a suitable dopant, this material can convert heat into electrical energy. Illustration: J.A. Koster, University of Groningen fullerenes already have a low in Milan are already creating thermal conductivity, but adding thermoelectric generators using the side chains makes it even fullerenes with a single side chain, lower, so the material is a very which have a lower ZT value than good phonon glass,’ says Koster. we now have.’ ‘Furthermore, these chains also incorporate the dopant and create The fullerenes, side chain and a very ordered structure during dopant are all readily available and annealing.’ The latter makes the the production of the new material material an electric crystal, with can likely be scaled up without an electrical conductivity similar too many problems, according to that of pure fullerenes. to Koster. He is extremely happy with the results of this study. ‘The We have now ‘We have now made the first paper has twenty authors from made the first organic phonon glass electric nine different research groups. crystal,’ Koster says. ‘But the We used our combined knowledge organic phonon most exciting part for me is its of synthetic organic chemistry, thermoelectric properties.’ These organic semiconductors, molecular glass electric are expressed by the ZT value. dynamics, thermal conductivity crystal but the The T refers to the temperature and X-ray structural studies to at which the material operates, get this result. And we already most exciting while Z incorporates the other have some ideas on how to further part for me is its material properties. The new increase the efficiency.’ material increases the highest thermoelectric ZT value in its class from 0.2 to Reference: Jian Liu, Bas van der over 0.3, a sizeable improvement. Zee, Riccardo Alessandri, Selim properties. Sami, Jingjin Dong, Mohamad Sensors I. Nugraha, Alex J. Barker, 'A ZT value of 1 is considered a Sylvia Rousseva, Li Qiu, Xinkai commercially viable efficiency, but Qiu, Nathalie Klasen, Ryan C. we believe that our material could Chiechi, Derya Baran, Mario already be used in applications Caironi, Thomas D. Anthopoulos, that require a low output,’ says Giuseppe Portale, Remco W. A. Koster. To power sensors, for Havenith, Siewert J. Marrink, example, a few microwatts of Jan C. Hummelen & L. Jan power are required and these Anton Koster: N-type organic could be produced by a couple thermoelectrics: demonstration of of square centimetres of the ZT > 0.3 Nature Communications new material. ‘Our collaborators 10 November 2020

UNIVERSITY OF GRONINGEN 9 In Focus When going in circles helps you stay put: How spin-orbit coupling leads to stable spins in color centers in materials by Carmem Maia Gilardoni

Quantum computing and communication promise to revolutionize the way in which we process and transfer information, just like transistors and the internet did in decades past. Quantum information technology allows us to process information differently than classical computing and could enable fundamentally secure communication: according to the laws of quantum mechanics, it is impossible for a third party to eavesdrop on your quantum communication channel without you knowing.

The communication between The spin can be used to store remote quantum systems is most quantum information efficiently: efficiently done using particles of generally, a spin interacts only light – so called photons. Thus, with a magnet, which makes one of the big challenges in the it relatively insensitive to the field is to find materials that will environment and allows it to efficiently hold onto their quantum live for a relatively long time. information and transfer it into A photon emitted by such a color light particles on demand. Some center can provide information of the major contenders in the about the quantum mechanical field are tiny blinkers present in state of the electron spins in it. crystalline materials like diamond or silicon, called color centers. Silicon carbide is an industrially These color centers are almost mature semiconductor that hosts omnipresent – in fact, they are a variety of color centers, several responsible for the bright color of of them interacting with light in ruby, emerald and sapphire. They the telecom band. This means that Carmem Maia Gilardoni working in behave like artificial molecules we can make use of the existing the lab. trapped in the crystals: they telecommunication infrastructure vibrate and interact with light to transfer quantum information can bounce off other electrons or like a molecule would, but the between these color centers. atoms, or interact with electric shape of these ‘artificial molecules’ In some of these color centers fields all around it), one would is determined by the crystal the quantum mechanical spin intuitively expect that the strong around it. property is strongly connected spin-orbit coupling would lead to the motion of the electrons to faster loss of the quantum In a color center, electrons interact (something that is called spin-orbit information stored in the spin. with external magnetic fields due coupling). Since the motion of But this is not what researchers at to a fundamentally quantum the electron is strongly influenced the University of Groningen find, mechanical property called spin. by its environment (the electron in their work published October

10 ADVANCED MATERIALS | WINTER 2021 ENTEG

2020 in New Journal of Physics (https://doi.org/10.1088/1367- Dr. Bose, Dr. Raffa and 2630/abbf23).

In this work, the team lead by Prof. Picchioni partners Caspar van der Wal investigates a type of color center containing in EU’s Horizon 2020 molybdenum atoms in silicon carbide, which interact with FET Open Program light at the near-telecom range and are subject to strong spin- orbit coupling. The researchers consortium used pulses of light to write and Dr. Ranjita K. Bose , Dr. Patrizio Raffa and Prof. Francesco read the spin state in these color Picchioni of the Engineering and Technology Institute centers and tracked how long the Groningen ( ENTEG ) are partners in a consortium that stored spin information lived in received a European research council FET-Open 2018- these systems. They find that 2020 grant. The consortium’s ‘ 5DNanoPrinting ’ project the spin information lived for has been awarded a grant of EUR 3.58 million, of which very long in these color centers the UG’s allocation is EUR 547,000. The goal of the – several seconds when cooled to project is to develop innovative smart materials and a temperature of 2 Kelvin (minus novel fabrication methods for micro and nano devices. 270 Celsius). So, how do they The Italian Institute of Technology is coordinator. explain their counter-intuitive result? In this particular ‘artificial The project titled ‘Functional & Dynamic 3D Nano- molecule’, they crystal only allows MicroDevices by Direct Multi-Photon Lithography’ the electrons to move in a circular aims to develop fast and inexpensive functional 3D path. Like a current in a coil, Nano- MicroDevices (NEMS/MEMS). MEMS, Micro this circular motion creates an ElectroMechanical Systems, are microscopic devices effective magnetic field, which with moving parts which are capable of accomplish a interacts very strongly with the specific task. They find applications in many fields such spin. Since this circular motion as consumer electronics, automotive and healthcare. is pinned by the crystal, they The approach aspires to become a novel gold standard find that spin-orbit coupling for micro/nano-technologies, similar to how 3D printing stabilizes the electron spin in has become a cornerstone of manufacturing technologies these color centers, and this leads in the last decade. to the long-lived spins. At higher temperatures, they find that the additional vibrational motion of Novel polymers The UG team of researchers will develop novel polymers, these ‘artificial molecules’ lead which will be used to make gradient structures with to additional interaction between varying mechanical properties and crosslinking. The the spin and the environment project’s consortium includes academic and industrial that destroys the spin quantum partners from Italy, Austria, Ireland and the Netherlands. information in these systems. The partners will bring expertise in chemistry, material science, physics and engineering. Several color centers in various crystals have similar spatial properties to the Mo color center FET Open FET Open supports the early-stages of science and in SiC. Thus, the researchers technology research and innovation around new ideas conclude, ‘these findings shine towards radically new future technologies. light into what processes are actually responsible for the loss of quantum information in this class of systems. Several suitable candidates have been overlooked in the past, partly due to their strong spin-orbit coupling. However, we find that they could have surprising and promising properties for the field of quantum communication’.

UNIVERSITY OF GRONINGEN 11 In Focus New High Speed AFM results featured as Spotlight in JACS

In an all Groningen research effort the groups of Prof. Marrink (GBB), Prof. Otto (Stratingh) and Prof. Roos (Zernike) have been able to follow fibre self-assembly in real-time at the nanoscale. Using a combination of High Speed AFM and Molecular Dynamics simulations the groups were able to scrutinize the nanomentre-scale mechanisms of self-replicating molecule assembly. The results appeared in the Journal of the American Chemical Society (JACS) and were featured prominently as a JACS Spotlight.

Putting the findings in perspective The broader significance of these findings for the field of self-assembly can be summarized as follows. In the assembly of one-dimensional objects (stacks or fibers) there is an obvious but mostly overlooked problem: the assembling material needs to find the growing end of the fiber. This is a 3-dimensional search problem that causes assembly to be slow as the number of fiber ends tends to be small (often in the nanomolar range). The researchers discovered that fibers can bind the assembling material at their sides and guide this material to the ends, thereby turning a 3-dimensional search problem into a 1-dimensional one and greatly enhancing the efficiency of assembly. This finding The goal of the project was to uncover the assembly constitutes a new mechanism for the assembly of mechanism of self-replicating molecules. While one-dimensional objects. Mechanistic insight into the Otto lab had already close to 10 years of assembly pathways, like the one unveiled here, experience with the studied system, within weeks are keenly sought after, but remain rare. of starting the project important and completely unexpected new insights into the mechanism of By combining the data from the different single- replication were found. In brief, it was already molecule and bulk experiments, the molecular known that self-replication involved assembly of dynamics simulations and the kinetic modelling, molecules into 1D-stacks, where the assembly the authors were able to make this step in our process somehow drives the synthesis of the understanding of self-assembly processes. The assembling material from smaller components work was published in J. Am. Chem. Soc. where (precursors). The combined High Speed-Atomic it was also highlighted as a JACS Spotlight. Please Force Microscopy (HS-AFM) and Molecular Dynamics see below for the links to the article and Spotlight. (MD) Simulations revealed that the stacks play an active role in the process by binding the precursors References: Sourav Maity, Jim Ottelé, Guillermo at the sides of the stacks, where they accumulate Monreal Santiago, Pim W. J. M. Frederix, Peter in reservoirs, and guiding them to the ends from Kroon, Omer Markovitch, Marc C. A. Stuart, Siewert which the stack grow (see animated HS-AFM .gif J. Marrink, Sijbren Otto, and Wouter H. Roos illustration). During this reservoir-assisted growth Caught in the Act: Mechanistic insight into process the free precursors are added to the growing Supramolecular Polymerization driven Self-Replication fiber (see figure) and thereby converted into the from Real Time Visualization; J. Am. Chem. Soc., molecules that replicate. 2020, Vol. 142, p. 13709–13717

12 ADVANCED MATERIALS | WINTER 2021 Stratingh First NWO ENW Prof. Sijbren Otto elected Team Science KNAW Award for Prof. member The Royal Netherlands Academy of Arts Minnaard and and Sciences (KNAW) has selected Dr. Buter eighteen new members, one of which is from the Faculty of Prof. Minnaard and Dr. Buter (UG, Stratingh Institute ), Science and together with Dr. van Rhijn (University of Utrecht) and Engineering Prof. Moody (Harvard), have been awarded the first NWO (FSE) of the University ENW Team Science Award. This cross-disciplinary team of Groningen. It concerns Prof. receives the award for the development of ‘Comparative Sijbren Otto, Professor of systems Lipidomics, a new strategy to study pathogenic bacteria that chemistry at the Stratingh Institute forms the basis for novel drug development, diagnostics for Chemistry. The KNAW has and vaccines’. approximately 550 members. The team is a cross-disciplinary team that has been They are chosen based on scientific working together for 14 years towards a common goal: achievements of researchers. The to identify the key molecules that promote progression and new Academy members will be response in tuberculosis. The team combines the strengths installed later this year. of synthetic and analytical organic chemistry, microbiology and immunology to reach their goals. An important detail About Prof. Otto - is that the team does not focus on proteins but on lipids. systems chemistry Prof. Sijbren Otto is a pioneer in The team makes discoveries using an ‘iterative approach’: systems chemistry, a new discipline Moody discovers novel lipids by comparing pathogenic in chemistry that studies networks and non-pathogenic bacteria; Minnaard synthesizes of interacting molecules and their the lipid(s); Van Rhijn studies their interaction with properties. Otto is using this the human immune system, and Buter prepares new approach to study the chemical light-activatable drugs gleaned from these results. The basis of life. He succeeded in combination of these complementary expertises and building systems with ‘dead’ techniques is what makes the work of this team unique. molecules made in the lab that can make copies of themselves, Besides pioneering in a new research field, the team with the aim to undergo Darwinian has also made their discoveries open for researchers evolution. Mutations occur during from all around the world. This knowledge and replication, subsequently followed reagents sharing initiative benefits the advancement by selection depending on the of lipid biology and sets a new scientific standard. chemical environment. This gives certain mutants the ability to The assessment committee feels that it concerns a strong replicate faster and win the race team that has been working together for a long time. The for resources available. Otto and scientific goal of the team is clearly defined and there is his group also show how self- a clear synergy between the team members and their replicating molecules can use expertise. Without this interdisciplinary character, the chemical energy to produce and research would likely not be as effective. Additionally, maintain more complex structures: the committee very much appreciates the fact that the a first step towards metabolism. newly synthesized lipids are freely available for everyone.

UNIVERSITY OF GRONINGEN 13 In Focus National research programme led by University of Groningen professor Katja Loos Polymer scientists cooperate with industry to create smart materials by Rene Fransen (ScienceLinX)

Katja Loos, Professor of Polymer Chemistry at the University of Groningen, is conducting science while industry representatives are looking over her shoulder. Loos does not consider this scary. On the contrary, it inspires her and her colleagues from six other Dutch universities. Together, they make up the new virtual research centre for Soft Advanced Materials (SAM), which received a €3.6 million grant from the NWO (Dutch Research Council) and industry partners.

‘Although our work is not focused the company representatives, it on applications, we asked our The companies decided on the is up to me to find a solution.’ industry partners to pick their programme’s general course by favourites from over a hundred selecting 12 projects from a long Curiosity driven research ideas,’ explains Loos. She list of research ideas. They are Most of the PhD students have wrote the programme proposal also involved in the annual review started their projects. So far, Loos and is now the programme’s of each project. ‘This allows them is excited about the interaction coordinator. Twelve PhD students to indicate whether they feel that with the commercial partners. will work on the selected projects. the project is still on the course ‘BASF is a German company but ‘The idea behind this is that that they envisioned at the start.’ they don’t really know what is the companies get to know the However, Loos stresses that the happening in the chemical labs research groups at the different PhD supervisors make the final in the Netherlands within the universities and that the young decision regarding the project’s fields of polymer science and researchers get the opportunity to progress. ‘If they disagree with soft matter. They are curious, experience the industrial partner’s R&D activities,’ says Loos.

Progress Four companies are participating in the SAM research centre: the Dutch chemical companies DSM (health, nutrition and materials) and Corbion (food and biochemicals), and Germany- based BASF (the second largest chemicals producer in the world) and BYK Altana (additives). Together, they are contributing The polymer based anti-fouling system €1 million to the programme. Illustration Annemarie Maan

14 ADVANCED MATERIALS | WINTER 2021 In Focus as is BYK Altana,’ says Loos. or to prevent your office chair largely a trial-and-error process. And the companies are already from causing stripes on the wall. The technique that Portale uses interacting with the students. ‘It ‘The application determines will help scientists to understand is inspiring for the students to the kind of polymers needed,’ what factors determine the final see a company representative says Kamperman. Creating the structure and hence the coating’s interested in their work.’ right polymers will be the major final properties. challenge in this project. The joint So, over the course of the experience of Kamperman and De It is a technique that he started programme, the industry Vos should help the PhD student to develop at the large European partners will learn more about to accomplish this. Synchrotron X-ray Facility (ESRF) what polymer scientists at Dutch in Grenoble (France). ‘Synchrotron universities are working on. The X-ray machine facilities such as the ESRF are scientists will gain better insight The project led by Giuseppe much more powerful and we into the companies’ needs, while Portale is not aimed at creating therefore use them in our research 12 curiosity-driven projects will new materials but at developing each time the system dynamics have been completed. new characterization techniques are faster than one second. The to study them. In the Physics & use of different X-ray tools allows Coating Chemistry building’s basement, us to study how atoms, molecules The projects cover three main Portale’s group constructed a and nanoparticles assemble in themes: adaptive materials, large, unique X-ray machine space and time.’ sustainability and platform that can be used to study the science. Four PhD students from nanostructure of materials More cooperation the University of Groningen take (solution, bulk and thin films) in With nearly all PhD projects part in the SAM consortium. Loos the 1-1000 nanometre range. One underway, Katja Loos will be busy is supervising two students with of the applications of this set-up coordinating and mediating, while sustainability-themed projects, is watching how paint dries in real also conducting science. ‘A major who will work on bio-based and time. Portale shoots X-rays at a advantage of this programme on biodegradable polymers. The sample, at small or wide angles, is that all university partners other two PhD students from depending on the length scales are in the Netherlands. So, it is Groningen are being supervised to be investigated. These then easy to meet up.’ Furthermore, by Prof. Marleen Kamperman bounce off and are focused on the companies involved are also (adaptive materials) and Dr a 2D position-sensitive detector. located nearby. ‘We even get Giuseppe Portale (platform spur-of-the-moment visits.’ At science). ‘The scattering pattern contains the end of the programme, all information about the surface partners will know each other The project that Kamperman is structure of the films,’ explains better, which should lead to more supervising (together with Prof. Portale. And not just about the cooperation between universities Wiebe de Vos from the University surface. By adjusting the incident and chemical companies. of Twente) aims to create a new angle, X-rays can penetrate into coating to keep surfaces clean. If the material to different depths all works well, the coating can be before they get scattered. This regenerated. The first step is to means that he is able to study, for ... companies create a polymer that will attach example, a 30-micrometre layer to a surface and that also has a of coating or paint at different get to know charged section that sticks out. depths. Furthermore, the method the research ‘We then add a second polymer is non-destructive and does not that has the opposite charge and affect the sample, enabling him groups at different properties that prevent fouling of to watch coatings form during the surface,’ explains Kamperman. drying. universities This second polymer will attach & young to the first polymer. ‘The link ‘That kind of information can between the two polymers can help producers to understand researchers get be broken by changing the acidity the drying processes and can or the salt concentration. This help them to refine coating the opportunity would enable us to recycle the formulations. My PhD student to experience the released polymer.’ will look at different coatings that closely mimic the commercially industrial partner’s The industry partners are available ones. All have the same interested in different applications. ingredients but in different R&D activities. Anti-fouling materials could be combinations.’ Currently, used to keep a ship’s hull clean changing the formulation is

UNIVERSITY OF GRONINGEN 15 In Focus X-rays reveal in situ crystal growth of lead- free perovskite solar panel materials by Rene Fransen (ScienceLinX)

Just over ten years ago, scientists discovered a new, promising material that could convert light into electricity: metal-halide perovskite. The first solar cell perovskites contained lead, which is toxic. Soon, perovskites were developed that were based on tin, but these were not very stable. A few years ago, scientists at the University of Groningen demonstrated that adding another type of perovskite – one that forms two-dimensional layers instead of three-dimensional crystals – increased the stability; however, it reduced efficiency. University of Groningen scientists have now ‘watched’ how thin films of tin-based perovskite Scheme of the experimental setup used to investigate the structural formation crystals grow. They discovered of perovskites thin films during spin coating. that in mixtures of 3D and 2D Illustration G. Portale, University of Groningen perovskites, the 2D component helps to orient the 3D-like crystals efficient materials are not very the journal Advanced Functional but, at the same time, the 2D stable, while lead is a toxic Materials on 31 March. perovskite forms an insulating element. University of Groningen layer that is in contact with the Photovoltaic cells that are based scientists are studying alternatives substrate. By breaking up this on hybrid perovskites were first to lead-based perovskites. Two insulating layer, it should be introduced in 2009 and rapidly factors that significantly affect possible to create more efficient became almost as efficient as the efficiency of these solar cells and stable tin-based perovskite standard silicon solar cells. These are the ability to form thin films solar panels. materials have a very distinctive and the structure of the materials crystal structure, known as the in the solar cells. Therefore, it Lead-based perovskites are perovskite structure. In an is very important to investigate very promising materials for idealized cubic unit cell, anions in situ how lead-free perovskite the production of solar panels. form an octahedron around a crystals form and how the crystal They efficiently turn light into central cation, while the corners structure affects the functioning electricity but they also present of the cube are occupied by other, of the solar cells. The results some major drawbacks: the most larger cations. Different ions of the study were published in can be used to create different

16 ADVANCED MATERIALS | WINTER 2021 In Focus perovskites. as the solvent evaporates. At the of the film. The addition of low beamline BM26B-DUBBLE at the concentrations of the 2D material Spin coating European Synchrotron Radiation produces a stable and efficient The best results in solar cells have Facility (ESRF) in Grenoble, photovoltaic material, while the been obtained using perovskites France, Portale investigated what efficiency drops dramatically at with lead as the central cation. happens during the tin-perovskite high concentrations of this 2D As this metal is toxic, tin-based film formation. material. alternatives have been developed, for example formamidinium Interface Insulator tin iodide (FASnI3). This is a ‘Our initial idea, which was based The experiments by Portale and promising material; however, it on ex situ investigation, was that Loi can explain this observation: lacks the stability of some of the the oriented crystals grow from ‘The 2D-like perovskite is located lead-based materials. Attempts the substrate surface upwards,’ at the substrate/film interface. have been made to mix the 3D Portale explains. However, the in Increasing the content of the FASnI3 crystals with layered situ results showed the opposite: 2D material to above a certain materials, containing the organic crystals start to grow at the air/ amount causes the formation cation phenylethylammonium solution interface. During his of an extended 2D-like organic (PEA). ‘My colleague, Professor experiments, he used 3D FASnI3 layer that acts as an insulator, Maria Loi, and her research team with the addition of different with detrimental effect for the showed that adding a small amounts of the 2D PEASnI4. In device’s efficiency.’ The conclusion amount of this PEA produces a the pure 3D perovskite, crystals of the study is that the formation more stable and efficient material,’ started to form at the surface but of this insulating layer must be says Assistant Professor Giuseppe also in the bulk of the solution. prevented to achieve a highly Portale [1]. ‘However, adding a However, adding a small amount efficient and stable tin-based lot of it reduces the photovoltaic of the 2D material suppressed bulk perovskite. ‘The next step is efficiency.’ crystallization and the crystals to realize this, for example by only grew from the interface. playing with solvents, temperature That is where Portale comes in. or specific perovskite/substrate Perovskites have been studied ‘PEA molecules play an active interactions that can break up the for a long time by Professor of role in the precursor solution formation of this thick insulating Photophysics and Optoelectronics of the perovskites, stabilizing layer.’ Maria Loi, while Portale developed the growth of oriented 3D-like an X-ray diffraction technique crystals through coordination at Reference: Jingjin Dong, Shuyan that allows him to study the rapid the crystal’s edges. Moreover, PEA Shao, Simon Kahmann, Alexander formation of thin films in real molecules prevent nucleation in J. Rommens, Daniel Hermida- time during spin coating from the bulk phase, so crystal growth Merino, Gert H. ten Brink, Maria solution [2] [3]. On a laboratory only takes place at the air/solvent A. Loi & Giuseppe Portale: scale, the perovskite films are interface,’ Portale explains. The Mechanism of Crystal Formation generally made by spin coating, resulting films are composed of in Ruddlesden–Popper Sn-Based a process in which a precursor aligned 3D-like perovskite crystals Perovskites. Advanced Functional solution is delivered onto a fast and a minimal amount of 2D-like Materials, 31 March 2020 spinning substrate. Crystals grow perovskite, located at the bottom

Scheme of the mechanism of crystallization from DMF/DMSO solution during drying for the 2D/3D perovskite films. Illustration G. Portale, University of Groningen

UNIVERSITY OF GRONINGEN 17 In Focus Researchers develop a new bioinspired polymer able to efficiently transport protons Spider Silk inspires a new class of synthetic ion-conducting polymers for future energy applications by Renee Moezelaar

Synthetic polymers have changed the world around us, and it would be hard to imagine a world without them. They have pervaded our life, making their way from simple plastic goods to sophisticated devices such as batteries and fuel cells. However, they do have their problems. It is for instance hard to precisely control their molecular structure from a synthetic point of view. This makes it harder to finely tune some of their properties, such as their ability to transport ions. To overcome this problem, a group of researchers headed by Dr. Giuseppe Portale from the University of Groningen (the Netherlands) decided to take inspiration from nature. The result was published in Science Advances on July 17: a new class of polymers based on protein-like materials and inspired to spider silk that work as proton conductors and might be useful in future bio-electronic devices.

‘I have been working on proton the Chinese Academy of Sciences: transport protons. conducting materials on and off ‘We could immediately see that since my PhD’, says Portale. ‘I proton conducting bioinspired But first they had to see if the idea find it fascinating to know what polymers could be very useful for would work. "Our first goal was makes a material transport ions applications like bio-electronics to prove that we could precisely so I work a lot on understanding or sensors.’ tune the proton conductivity of and optimizing structures at the the protein-based polymers by nanoscale level to get greater More active groups, tuning the number of ionic groups conductivity.’ But it was only a few more conductivity per polymer chain". A number years ago that he considered the What do spiders have in common of unstructured biopolymers possibility of making them from with batteries? Nothing so far, that had different numbers of biological, protein-like structures. but the material developed in the ionisable carboxylic acid (-COOH) That was something the assistant research published in Science groups was prepared. Their proton professor came up together with conductivity scaled linearly with Advances on July 17 by G. Portale Prof. Andreas Hermann, a former and co-workers may change this the number of charged carboxylic RUG-colleague now working at in the future. The inset shows a acid groups per chain. ‘It was the DWI - Leibniz Institute for robust membrane created using a not ground breaking, everybody Interactive Materials in Germany spider silk inspired polyelectrolyte knows this concept. But we and Prof. Kai Liu from Changchun that is capable of efficiently were thrilled by the possibility Institute of Applied Chemistry at to design something that worked

18 ADVANCED MATERIALS | WINTER 2021 In Focus as expected’ Portale says.

For the next step, Portale relied on his expertise in the field of synthetic polymers: ‘I have learned over the years that the nanostructure of a polymer can greatly influence the conductivity. If you have the right nanostructure, it allows the charges to bundle together and increase the local concentration of these ionic groups and that gives a dramatic boost to the proton conductivity.’ Since the first batch of biopolymers was completely disordered, the researchers had to switch to a different material. They decided to use a known protein having the shape of a nanosized barrel. ‘We engineered a protein already existing in nature that has the structure What do spiders have in common with batteries? Nothing so far, but the of a barrel of few nanometers material developed in the research published in Science Advances on July 17 and added strands containing by G. Portale and co-workers may change this in the future. The inset shows carbocyclic acid to its surface’, a robust membrane created using a spider silk inspired polyelectrolyte that is Portale explains. ‘This increased capable of efficiently transport protons. the conductivity greatly.’ very beneficial for the proton to find out if our polymer can A novel spider silk conductivity’, Portale explains. make a difference there, since it inspired proton ‘And we were able to turn it is already bio-compatible.’ conducting polymer into a robust centimetre-sized membrane.’ A nice achievement For the short term, Portale Unfortunately, the barrel-polymer if we consider that the measured mainly thinks about sensors. was not very useful. It had no proton conductivity is one order ‘The conductivity we measure mechanical strength and it was of magnitude higher than in our material is influenced by difficult to process, so Portale and those of any previously known the environment, like humidity, his colleagues had to look for biomaterials. volatile chemical species or another alternative. They landed temperature. So changes in all on a well-known natural polymer: But they are not there yet these quantities can be measured spider silk. ‘This is one of the most according to Portale: ‘This was using our material.’ However, fascinating materials in nature, mainly fundamental work. In order before all these dreams come because it is very strong but can to really apply this material, we true, there are a lot of questions also be used in many different really have to improve it and to be answered. ‘I am very proud ways’, says Portale. ‘During my make it processable.’ that we were able to design, make time at the European Synchrotron and control these new materials laboratory, I have learned about Dreams on a molecular scale, and build the fascinating nanostructure of But even though the work is not them from scratch. But we still the spider silk. We have thus yet done, Dr. Giuseppe Portale and have to learn a lot about their engineered a protein-like polymer his co-workers can already dream capabilities and see if we can that has the main structure of about applying their polymer: improve them even further.’ spider silk but was modified to ‘We think this material could be host the strands of carbocyclic useful as a membrane in future Reference: De novo rational design acid that we prepared before’ energy devices. Maybe not for of a freestanding, supercharged the large scale systems that you polypeptide, proton-conducting The novel material worked like see in cars and factories, but membrane. Chao Ma, Jingjin a charm. ‘We found that it self- more on a small scale. There is a Dong, Marco Viviani, Isotta Tulini, assembles at the nanoscale growing field of implantable bio- Nicola Pontillo, Sourav Maity, Yu similarly to spider silk while electronic devices, for instance Zhou, Wouter H. Roos, Kai Liu, creating dense clusters of glucose-powered pacemakers. Andreas Herrmann and Giuseppe charged groups, which are In the coming years we hope Portale

UNIVERSITY OF GRONINGEN 19 In Focus Detailed model important step towards understanding Huntington’s by Renee Moezelaar

Huntington’s disease is still a quite mysterious disease. It is genetic and causes brain cells to degrade over time. Many researchers have tried to figure out what happens, but no-one has been able to find a cure yet. But thanks to associate professor Patrick van der Wel this might be a step closer. He and his team of researchers came up with a new, more detailed and specific molecular model of the mutated part of huntingtin, the protein that plays a big part in this disease. The model was published in the Journal of Molecular Biology on June 27th.

‘If you want to cure or find a ‘We are looking at a number of medicine for a disease, you Folding and unfolding different paths. It would be great first have to understand how In order to figure this out, Van der if we could use our model to find it works’, says Van der Wel. Wel’s PhD student Jennifer Boatz molecules that can bind to the Unfortunately this is not yet the used techniques like electron protein and prevent the wrong case for Huntington’s disease. ‘For microscopy and NMR to learn kind of folding. On the other Huntington’s we have a general more about the structure of the hand we also want to look at idea, but details are not yet clear. huntingtin protein and see how it diagnostics, and use the model That is why we started working folds. All this analysing resulted in to detect the clusters in a much on our model.’ a very elaborate model of clusters earlier stage of the disease. formed by the mutant Huntingtin And lastly I would really like to Faulty gene protein, the most detailed so far. investigate what happens when Van der Wel and his colleagues According to Van der Wel, the one of these clusters forms and have been working on Huntington’s model is an important first step how it pushes other clusters to disease for a couple of years now. towards better understanding: form.’ ‘We know that Huntington’s is ‘Understanding the way the caused by a faulty gene that protein folds is very important So there is still a lot of work to gives a mutation in the protein for understanding the disease. be done. For now, Van der Wel huntingtin’, Van der Wel explains. And with this model the whole focusses on further improving ‘Due to this mutation the patients world can make more sense of the model. ‘We are working with get clusters of proteins in the what happens.’ the campaign team Huntington brain, similar to what happens to take the next step. We really with Parkinson’s or Alzheimer’s.’ However, the model is not the only want to go to the atomic structure, important find. The researchers and understand all the details. The clusters are associated with also discovered that the structure Because the more we know, the the development of symptoms, so the protein formed depended on better we can fight this disease.’ researchers were eager to find out the concentration. ‘This is very how they form exactly. Studying important to know, since we tend Reference: Protofilament Structure of this process revealed that to use very high concentrations if and Supramolecular Polymorphism of the mutated huntingtin protein we study this protein in the lab. Aggregated Mutant Huntingtin Exon undergoes polymorphism: it can But in our body the concentration 1. Boatz, J.C., Piretra, T., Lasorsa, A., fold in different ways and have is very low, so if we want to mimic Matlahov, I., Conway, J.F. & Van der Wel, multiple structures. Van der Wel: the situation in our bodies we P.C.A. (2020) J. Mol. Biol., 432(16): ‘In biology we often expect one need to change our approach.’ 4722-4744. (Open Access) protein to have one structure and one function. But huntingtin New research turns out to do good as well as The associate professor hopes bad things. We wanted to figure that all this information will lead out how and why this happens.’ to new and interesting research:

20 ADVANCED MATERIALS | WINTER 2021 In Focus Scientists create coatings from nature UG and AkzoNobel join forces to develop the green chemistry of the future

Organic chemists from the University of Groningen and the Dutch multinational company AkzoNobel, a major global producer of paints and coatings, developed a process that allows them to turn biomass into a high-quality coating using light, oxygen and UV light. This process combines a renewable source with green chemistry and could replace petrochemical-based monomers such as acrylates, which are currently used as building blocks for coatings, resins and paints. A paper on the new process was published in the journal Science Advances on 16 December.

Coatings are everywhere, from it suitable for the production of linked polymers with different the paint on your house to a coatings,’ explains Hermens. properties.’ For example, while protective layer on the screen He used a process that has all polymers would coat glass, of your smartphone. They been developed in their group one combination was able to also protect surfaces from scratches, to convert the furfural into a form a coating on plastic. And by influences of the weather or compound, hydroxybutenolide, adding more rigid monomers, a everyday wear. Most coatings that resembles acrylic acid. ‘The harder coating was formed, with are made up of polymers based chemical conversion uses only properties comparable to those on acrylate monomers, with the light, oxygen and a simple catalyst of coatings on cars. In this way, global production of acrylate and produces no waste. The only these coatings are adaptable for exceeding 3.5 million tonnes a side product is methyl formate, different purposes. year, all produced from fossil oil. which is useful as a replacement for chlorofluorocarbons in other Patent Biomass processes.’ ‘We managed to create coatings To make these coatings more from a renewable source, sustainable, scientists from the Less reactive lignocellulose, using green University of Groningen, led by Part of the structure of chemistry,’ concludes Hermens. Professor of Organic Chemistry hydroxybutenolide is similar ‘And the quality of our coatings Ben Feringa, teamed up with to acrylate, but the reactive is similar to that of current scientists from coating producer part of the molecule is a ring acrylate-based coatings.’ For AkzoNobel. ‘We wanted to use structure. ‘This means that it is two steps in the process, patent lignocellulose as the starting less reactive than acrylate and our applications have been filed with material,’ says George Hermens, a challenge was to further modify AkzoNobel, the industrial partner PhD student in the Feringa group the molecule so that it would in the project. Hermens is now and first author of the paper in produce a useful polymer.’ This working on a different building Science Advances. Lignocellulose was achieved by adding different block derived from furfural to makes up 20 to 30 per cent of green or biobased alcohols to produce other types of polymer the woody parts of plants and is the hydroxybutenolide, creating coatings. the most abundantly available four different alkoxybutenolide raw biomass material on Earth. monomers. Partners Currently, it is mainly used as The project was initiated by a solid fuel or used to produce Coatings the Advanced Research Center biofuels. These monomers can be Chemical Building Blocks transformed into polymers and Consortium (ARC CBBC), a Hydroxybutenolide coatings with the help of an Dutch national public-private ‘Lignocellulose can be cracked initiator and UV light. ‘Coatings are research centre that develops new with acid to produce the chemical made up of cross-linked polymer chemical processes and chemical building block furfural, but this chains. By combining different building blocks for novel energy needs to be modified to make monomers, we could get cross- carriers, materials and chemicals Continued on p. 23 UNIVERSITY OF GRONINGEN 21 In Focus Elisabetta Chicca new professor Bio-inspired Circuits & Systems “If we cannot build neural networks, we can’t understand them properly”

Our brains are one of the most complicated machines we know, but little by little researchers are able to figure out more details. Some researchers are even able to translate the processes of the brain into electrical systems. Elisabetta Chicca is one of these researchers, and in August she joined the Zernike Institute as professor Bio-inspired Circuits & Systems.

“I am very excited about joining building electrical circuits that The main reason Chicca wants to this team”, says the newly mimic the processes of neurons mimic the processes in the brain appointed professor. “I was and synapses.” is to get a better understanding welcomed with open arms and of how these processes work. feel like a lot of people in the More interdisciplinary “Feynman used to say: what I institute would like to cooperate Chicca started her career as a cannot create, I do not understand. with me, so there will be a lot of physicist at the University of Rome, I think this is true because when interesting new opportunities.” but her research soon became we build our neural networks it more interdisciplinary. “When I gives us many new insights. I’m Chicca’s work is said to be one started my PhD in Zurich I was not saying the environment is of the missing pieces, the step only familiar with the theoretical exactly the same, but we do that was so far missing from the physics side of building neural encounter space and energy institute: “A lot of people study networks, so I had to learn a lot constraints that might also play the brain and make models of how about neurobiology and electrical a role in the brain.” certain processes work, but these engineering. But this made me models are often very abstract appreciate this field of research One of her favourite projects at and they live in an ideal world. I even more.” the moment is that of PhD student work on the next step: actually Thorben Schoepe. In this project,

22 ADVANCED MATERIALS | WINTER 2021 In Focus she is trying to understand insect generous offer from the Zernike navigation. “We look at the way and CogniGron Institutes I also a honeybee navigates through an Feynman recently got some funding, so environment, looks for flowers, my group will be able to grow and goes back to the beehive”, used to say: and take on more and more she explains. “This sounds simple interesting projects.” enough, but it requires a lot of what I cannot different tasks to be performed create, I do not One of the topics she would like simultaneously and in the right to focus on is learning. “We know order. Just to keep flying is already understand. I a bit about how people learn, very complicated.” for instance, that the synapse think this is true changes while we learn. But there Thanks to her collaboration with because when is no general theory that can the group of professor Martin bring it all together. One of my Egelhaaf at Bielefeld University, we build our dreams would be to find such a they were able to develop a neural networks theory, and explain everything.” computational system: “With the knowledge of the biologists, it gives us many Meanwhile, she is getting used we developed a system which new insights. to living in Groningen. “I have exhibits interesting behaviors been here so many times before, comparable to that of the biological but it is still a bit unreal that counterpart. We can use this I am actually living here now. system to verify the hypothesis are in the environment and used I am getting to know the city about the computational role of its output to change the speed even better now and enjoying bits and pieces of the insect brain.” of the robot. This was enough the beautiful nature. I love it, to substantially improve the and everybody is making such an Using this model, the researchers performance of the robot.” effort to make me feel at home, build a neural network that powers both professionally and personally. a small robot. Chicca: “When Applying the system I look forward to advancing my it encounters an obstacle, it Of course, these kinds of processes research here for many years will make a turn and avoid it.” won’t only yield fundamental to come.” Unfortunately, the robot seemed insights. Chicca hopes she can to bump into the obstacles way also contribute to some real-life Continued from p. 21 more often than a bee would. The applications. “It would be great if for sustainable chemistry. The problem, as it turns out, was one we could build a system that does ARC CBBC is a national initiative missing neuron. “In nature, the something artificial intelligence with partners from industry, bee slows down if the environment is not yet able to do. Our work academia and government.There is too crowded. We added a single can provide solutions for tasks are three universities involved neuron to our neural network that conventional computing (Utrecht University, the University that senses how many obstacles can’t manage because of the of Groningen and Eindhoven limited availability of resources University of Technology) like energy and data. We can and major industrial partners for instance aim to equip small (AkzoNobel, Shell, Nouryon and navigating agents running on BASF), as well as the ministries We look at the batteries with cognitive abilities, of Education, Culture and Science so that they can navigate through and of Economic Affairs and way a honeybee complex environments and, for Climate Policy and the Dutch navigates example, search for survivors in Research Council (NWO). a rescue scenario.” through an Ben Feringa environment, But she also aims at investigating Hermens’ supervisor, Ben new technological solutions thanks Feringa, is one of the founders looks for flowers, to collaborations at Zernike. of this centre. Feringa: ‘The “Several groups here are exploring programme entails all the steps and goes back novel materials and their use for from fundamental scientific to the beehive ... computation. The possibilities to discovery to process and product collaborate with them open new development. In this long-term exciting avenues for my research.” partnership, universities and the Chicca is already busy setting up chemical industry join forces to collaborations with colleagues at develop the green chemistry of the Zernike Institute. “Besides the the future.’

UNIVERSITY OF GRONINGEN 23 In Focus Simple explanation suffices for conduction in nickelates

by Rene Fransen (ScienceLinX)

Scientists are looking for new materials to build computers that work in a similar way to a human brain. Such materials should be able to switch from being insulators to being conductors. Neodymium nickel oxide shows this behaviour yet it was unclear as to exactly what makes the electrons in the material move in the way that they do. It has been suggested that this is determined by interactions between the spins (a magnetic property) of the electrons of the nickel ions. However, University of Groningen scientists have discovered that a simpler explanation may suffice: strain and missing ions in the material increase the resistivity and can deceivably mimic the temperature dependence of the resistivity close to a magnetic phase transition. This improved knowledge will help in the development of electronics that can emulate neurons.

Some metal oxides, such as that otherwise prevents them of Functional Nanomaterials nickelates, have a tuneable from moving. and Director of the Groningen resistivity, which makes them an Cognitive Systems and Materials interesting material for adaptable Exotic explanations Center (CogniGron) at the electronics and cognitive ‘In some oxides, such as University of Groningen. She and computing. These materials can nickelates, a transition from her PhD student Qikai Guo are change their nature from metallic insulator to metal can occur but interested in nickelates because it to insulating. How exactly this it is not clear how this happens,’ is possible to tune their resistivity. metal-insulator transition takes says Beatriz Noheda, Professor They could be used in devices that place is a topic of great interest in condensed matter physics. However, even the metallic behaviour in nickelates seems unusual. Scientists from the University of Groningen, together with colleagues from Spain, have now found that it is not as complex as was previously assumed. The results were published on 11 June in the journal Nature Communications.

In a metal, electrons can move freely, whereas in insulators, they are strongly localized around the atomic nuclei. When a metal is heated, the ions’ vibrations (called phonons) scatter the moving electrons and increase the resistivity. In contrast, heating Materials close to a metal-insulator transition (MIT) have great potential in

can generate conductivity in some synaptic devices. The figure shows the behaviour of the resistivity of NdNiO3 as insulators, when electrons receive a function of temperature upon changing its oxygen content: the exponent that enough energy to be released describes the metallic state can be gradually tuned from n=1 to n=3, tuning at and cross the energy band gap the same time the resistance change at the MIT. Illustration: B. Noheda, UG

24 ADVANCED MATERIALS | WINTER 2021 In Focus emulate the way that synapses not an intrinsic property. Noheda: emulate the way that neurons in our brain work. ‘That led us to systematically look work. That is the ultimate goal of at samples grown on different Noheda and her team. ‘We now ‘Before we can do this, we should substrates.’ The results showed know that these nickelates are understand what the nature of the that in perfect films, the exponent more similar to normal metals simplest state, the metal state, is 1, which means that the than we previously thought. This is. This means understanding how resistivity is caused by phonons, means that they can be quite electrons move around in the as it is in normal metals. However, good conductors if we ensure material when an electric field is when the substrate that is used that there are no ion vacancies applied to them,’ explains Noheda. induces strain in the thin film, in the crystal. In this way, the A linear change in resistivity (an the exponent changes. transition to the insulating phase exponent of 1 in the curve that brings about larger changes in represents the resistivity as a The strain leads to oxygen resistance, leading to synaptic function of temperature) can be vacancies in the crystals and devices with improved plasticity.’ explained by a simple model in changes the forces between the which the electrons are impeded ions and, therefore, the electronic In these experiments, the change by the vibration of the ions. energies. That in turn changes the in resistivity in these nickelates ‘However, for an exponent that materials’ resistivity. ‘What we was induced by an increase in is not 1, more exotic explanations found out is that we can control temperature. ‘This is of course have been suggested, based on the amount of vacancies and not ideal when you want to make the presence of fluctuations in continuously tune the resistivity a device. Our next step is to the spins of the nickel electrons exponent at will, which is a tuning design the material in such a and electron-electron interactions knob that we did not know we way that we can tune resistivity that occur when the system is had. Thus, understanding the using an electric field,’ Noheda close to a quantum critical point.’ metal state in these nickelates concludes. may not require exotic electron- Strain electron interactions,’ Noheda Reference: Qikai Guo, Saeedeh However, in thin films of concludes. Farokhipoor, César Magén, neodymium nickelate (NdNiO3), Francisco Rivadulla, and Beatriz Noheda and her team observed Learning how to control the Noheda: Tunable resistivity that the exponent was 1 in some metal state and the transition exponents in the metallic phase samples, while in other samples to the insulator state will help of epitaxial nickelates. Nature of the same material, it was not. scientists to design electronics Communications, 11 June 2020 This suggests that the exponent is based on nickelates, which can

Provinces and SNN support research into production of plastic from sugar

How can we make bioplastics from sugar in an efficient way, so that the price becomes comparable to that of plastics from petroleum? This is what the University of Groningen with project leader Prof Gert-Jan Euverink of ENTEG and various companies and knowledge institutions will be researching over the next three years.

The province of Groningen, the province of Drenthe and the Samenwerkingsverband Noord-Nederland (SNN) jointly support the sustainable initiative with a subsidy of almost 1.2 million euros. More than 900,000 euros comes from a European EFRO subsidy. If the research shows that plastics from sugar can compete with plastics from fossil fuels, this can be a huge boost for the environment and the northern economy. If successful, the project can create 60 to 85 new jobs in a follow-up phase.

UNIVERSITY OF GRONINGEN 25 In Focus New assistant professor in our team - Jagoda Sławińska “I think theorists can work more closely with experimentalists”

The University of Groningen has for a long time been among the top influencers globally in spintronics research. The reputation of the Zernike Institute for Advanced Materials has continued to attract the best talent, and recent years have seen some promising research in the spintronics field.

A newcomer preparing for her start at the institute in September, As the name suggests, the Jagoda Sławińska is an assistant main goal of LIM is to enable professor with experience in computational operations within a spintronics and two-dimensional memory array, thereby reducing materials and a rare hands-on the time required to access approach to research. the conventional memory and Although Sławińska has “plans improving the energy efficiency Closer collaboration for purely theoretical research,” of the system. Sławińska is also excited she is also keen to “work very by the potential industrial closely with experimentalists” In 2018, researchers at Intel applications of 2D materials — in her new role. published a paper describing namely, heterostructures and a magneto-electric spin-orbit hybrid systems — related to “My areas of interest are novel (MESO) logic device with the memories and novel computing materials for spintronics and potential to decrease the voltage architectures. She is currently novel phenomena related to spin- required by 80 percent and researching methods of designing orbit physics, taken in strong overall energy consumption by a new material with the properties connection with low-dimensional as much as 97 percent compared needed for such applications systems and 2D materials,” she to conventional complementary through the stacking of different added. metal-oxide-semiconductors layers of atomically thin materials. (CMOS). Spin-orbitronics’ Sławińska plans to continue potential This breakthrough inspired working on this topic in Groningen Although there hasn't been Sławińska to engage further “as there are groups working on a major breakthrough in the with the topic and this research similar problems.” research of spin transistors in direction is now one of her main more than two decades, recent areas of interest. Her focus now “We want to study 2D materials, studies have shown that they is on exploring the applications of including stacks of transition could be used in logic-in- multiferroics and spin-orbit related metal dichalcogenides (TMDC) memory (LIM) applications. phenomena with LIM arrays and that are broadly investigated in This architecture, popularised seeking out the best materials Groningen — but then I also want among others by researchers at to use in these devices. to go beyond that,” she said. the chipmaker Intel, may bring a significant performance boost Sławińska has emphasized the to future CPUs. strength of experimentalist

26 ADVANCED MATERIALS | WINTER 2021 In Focus groups at the Zernike Institute closely with experimentalists, Łódź in Poland before working at for Advanced Materials and their with the industry. We can still the Spanish and Italian National rich experience in growing 2D contribute to the construction of Research Councils. Her latest material layers. A researcher with some new devices. Maybe not postdoctoral position since April a strong hands-on approach, she in detail — but in general by 2018 was in the Department of has become a major proponent of proposing new phenomena and Physics at the University of North close collaboration between the the ways of connecting several Texas. Her working experience of theoretical and practical sides of different effects to get specific a wide range of institutions allows academia and is always interested functionality.” Sławińska to compare how the in industrial applications of her academic ecosystems function research. Sławińska is also no stranger across the world. to coding her way through “Often in theoretical papers, complicated computations. “Generally, in the US the research- you'd find statements like ‘it bound money is more mobile,” can be useful for spintronics “I normally get involved in she explained. “Sure, you pay applications,’” she added. “This is software development if I need more to attend conferences and a general statement. […] What's to solve a particular problem,” so on, but at the same time, different about me in this sense is she explained. “So, my group people are more active. I've that I have papers that are looking won't be development-oriented been involved in more meetings solely at new devices. The main — but I am looking for students and collaborations here; it's an goal of one of my recent papers who are prepared to code. If environment that's not inert.” was to describe and demonstrate you need to measure something that a specific device could be in an experiment, and that Now the researcher plans to use constructed and work. measurement is not implemented her international experience to in any of the known libraries, embrace the best practices she “This is not common for a then it's important that you can has been exposed to over the theoretician — and of course, write your own module to do it.” years. it's also very risky; you can propose many things but it's “I'm used to working “For example, I believe that in the hard to demonstrate that they fast” US people in and around academia will work. However, I still think Sławińska obtained her PhD act faster than elsewhere,” she that theorists can work more degree at the Department of Solid said. “Now, I'm used to working State Physics of the University of fast too.”

Often in theoretical papers, you’d find statements like ‘it can be useful for spintronics applications. This is a general statement. The main goal of one of my recent papers was to describe and demonstrate that a specific device could be constructed and works. This is not common for a theoretician; it’s also very risky.

UNIVERSITY OF GRONINGEN 27 In Focus Finding the missing mirror in spintronic nanodevices

When it comes to next-generation electronics beyond the current silicon-based technologies, spintronics is a top contender. It uses spin, the magnetic property of electrons, instead of their electric charge, to encode and decode digital information. A challenge surrounding spintronics is to efficiently convert between spin and charge signals. Usually, scientists use relatively large magnetic materials for this purpose, but a number of experiments in the past years seem to indicate that some tiny molecules with a certain shape can do the same trick too. You may wonder, can we then use these molecules in spintronic devices? If so, what kind of signals can we get? And what do these signals tell us about the molecules? This is exactly what PhD student Xu Yang, prof. Caspar H. van der Wal, and prof. Bart J. van Wees from the Zernike Institute for Advanced Materials (ZIAM, University of Groningen, the Netherlands) wish to answer with their new theory. Their results were recently published in the journal Nano Letters.

The Missing Mirror signal—the magnetoresistance a new theoretical tool to model The special thing about these (MR) signal—from arising in these spintronic nanodevices, molecules is that their mirror the linear regime (the common and they can indeed largely images are different from operating regime of electronic reproduce signals that were themselves. Think of it as your nanodevices). This was pointed observed in past experiments. hands. The mirror image of your out in an earlier publication from ‘Thanks to the new understanding left hand is your right hand— the same ZIAM physicists, and beyond linear regime, we can and it cannot fit comfortably in now in their new publication, now explain what determines the your left-handed glove. These they show that the MR signals sign of these signals.’ Moreover, molecules are called chiral can indeed emerge as we go they propose a completely new molecules, and they are widely beyond the linear regime. type of spintronic nanodevice— available in nature, especially one that is fully built from chiral in living organisms. Being able ‘To generate the MR signals outside molecules, without using any to use them for spintronics has the linear regime, electrons with magnetic materials at all. It huge potentials. It not only allows different energies must experience relates the digital bits of 0 and for even smaller nanodevices, different environments as they 1 to the opposite mirror images but can also dramatically reduce travel through the spintronic of chiral molecules, and opens the cost of such devices. What’s nanodevice,’ explains Yang, ‘and up the possibility of processing more, it opens up an avenue they must lose some of their digital information by controlling of using spintronic technologies energy.’ In this way, a nanodevice the shape of these molecules. for chemical and biological containing a molecule, a magnet, ‘We hope these results bring applications. This is exactly why and two electrodes can indeed further understandings to the it is so important to understand tell whether the molecule is fundamental connection between the link between these chiral chiral, and can even distinguish molecular chirality and electronic molecules and spintronic signals the opposite mirrored forms of spin, and inspire the design of coming from nanodevices. such molecules. This result also future spintronic devices.’ goes beyond molecules, since Spintronic Signals the missing mirror symmetry is Reference: Xu Yang, Caspar H. van It turns out that, if one simply only about geometry, not the der Wal, and Bart J. van Wees, uses chiral molecules to replace chemistry, which means it can Detecting Chirality in Two-Terminal a magnet in typical spintronic happen for other materials as well. Electronic Nanodevices, https:// nanodevices, fundamental pubs.acs.org/doi/full/10.1021/ laws of nature would prevent Future Nanodevices acs.nanolett.0c02417, Nano the characteristic spintronic The ZIAM physicists also provide Letters, July 16, 2020.

28 ADVANCED MATERIALS | WINTER 2021 In Focus Resilience and Adaptability: New pathways with Skyrmion bubbles

Researchers from the University of Groningen and TU Wien have detected signatures of the skew scattering in the ferromagnetic conductor, SrRuO3, associated with topological magnetic bubbles. This effect showed a surprising adaptability to different substrate surfaces and unique resilience to variations of temperature, strength and direction of the applied magnetic field. This research was published on July 27, 2020, as a Rapid Communication in Physical Review Research.

Resilience and Adaptability: New pathways with Skyrmion bubble

Magnetic bubbles are cylindrically highly suitable for novel high- interfaces for new magnetic shaped islands with reversed density magnetic memory devices. memory technologies and magnetization that can be set The magnetic dipoles in the novel hardware components for into motion by electric current nanosized bubbles, also known alternative computing strategies. pulses. They have been discovered as skyrmions, form a knot that about fifty years ago and were cannot be easily unwound. This This research is conducted by immediately employed to store non-trivial topology gives rise to two research groups of the UG’s digital information in non-volatile a skew scattering of electrons Zernike Institute of Advanced memory that can withstand harsh off skyrmions – the so-called Materials (ZIAM), led by Prof. environments. Topological Hall Effect. Tamalika Banerjee (PhD students Ping Zhang and Arijit Das), Prof. The recent discovery that in chiral The detection of signatures Maxim Mostovoy (PhD students magnets the size of magnetic of the skew scattering in the Evgenii Barts and Maria Azhar), bubbles can be reduced to a few ferromagnetic conductor, and by researchers of the TU nanometers, spurred the interest SrRuO3, advances the field of Wien, Austria. in them. This extremely small skyrmionics. It provides significant dimension makes the bubbles opportunities to tailor device

UNIVERSITY OF GRONINGEN 29 In Focus New model helps to describe defects and errors in quantum computers by Rene Fransen (ScienceLinX)

A summer internship in Bilbao, Spain, has led to a paper in the prestigious journal Physical Review Letters for Jack Mayo, a Master’s student in Nanoscience at the University of Groningen. He has helped to create a universal model that can predict the number distribution of topological defects in non-equilibrium systems. The results can be applied to quantum computing and to studies into the origin of structure in the early Universe.

Jack Mayo is a student of the Top Master Programme in Nanoscience at the Zernike Institute for Advanced Materials at the University of Groningen. Last year, he received an email, circulated by one of the programme’s supervisors, with a list of summer internships that were offered by the Donostia International Physics Center (DIPC) in San Sebastián, Spain. One project caught his eye. ‘This was a theoretical project related to condensed matter, but it also had some clear technological relevance. I wanted to find out if this kind of work would suit me,’ he explains. Mayo applied and was selected, so he spent his 2019 summer holidays on the Basque coast, immersed in Dr Luis Pedro García-Pintos, Dr Aurélia Chenu, Prof. Adolfo del Campo, Iñigo theoretical physics. Perez, Léonce Dupays and Jack Mayo (left to right).

Ice crystals The project that he participated of order (for example, order start to align with each other.’ in, together with the research induced by cooling) is almost group led by Professor Adolfo always accompanied by the This alignment will begin at del Campo at the DIPC, was development of defects. ‘Take certain uncorrelated points in aimed at solving a problem in a system in which particles have a medium and then grow – quantum computing – but it has a magnetic moment that can flip like ice crystals in water. The much wider implications, from between up and down,’ Mayo alignment of each domain (up nanoscale magnets to the cosmos. explains. ‘If you increase their or down in the example of the In all these systems, the onset attractive interaction, they will magnetic moments) is a matter

30 ADVANCED MATERIALS | WINTER 2021 In Focus of chance. ‘Local alignments will grow outwards and at a certain stage, domains will begin to meet and interact,’ says Mayo. For example, if an up-domain meets a down-domain, the result will be a domain wall at their interface – a symmetry-breaking defect in the ordered structure, leaving behind an artifact of the material in its higher-symmetry phase.

Travelling salesman This annealing of a medium is described by the Kibble-Zurek mechanism, originally designed to explain how a phase transition resulted in ordered structures in the early Universe. It was subsequently discovered that it could be used to describe the transition of liquid helium from a fluid to a superfluid phase. ‘The mechanism is universal and is also used in quantum computing based on quantum annealing,’ explains Mayo. This technology At the point at which the energy landscape splits, the high symmetry chain is already on the market and decays into a lower symmetry state when the critical point is passed. In this is capable of solving complex case, a straight chain decays into a zig-zag configuration when the anisotropy puzzles such as the travelling \lambda(t) passes a critical value \lambda_{c}. Where two consecutive ions salesman problem. However, a fall onto the same side, a state of higher energy locally, we observe a defect. | problem with this type of work Illustration Fernando Gómez-Ruiz - Donostia International Physics Center is that defects that occur during the annealing process will distort the results. distribution during cooling. As each domain can have one of two Simulations Amsterdam values (up or down in the example Now, almost a year later, Mayo The number of defects that of the magnetic moments), they is finishing his Master’s thesis show up in quantum annealing could estimate the chances of in functional spectroscopy. He depends on the time taken to two opposite domains meeting has learned that he has a taste pass the phase transition. ‘If you and creating a defect. This led for analytical work and, after have millions of years to slowly to a statistical model based on graduating, he will start a PhD change the interactions between binomial distribution, which could project intheoretical machine units, you do not get defects, but be used to predict how a system learning at the University of that is not very practical,’ Mayo should be cooled to create the Amsterdam. ‘I am finishing up remarks. The trick is in designing smallest number of defects. work on a quasi-classical approach finite-time – and therefore more The model was verified against to model the defects, which was practical – schedules to obtain independent numerical simulations also started in Spain. But first an acceptable number of defects and appeared to work well. This things first.’ with high probability. The research new model was described in a project in which he participated paper that was published on 17 Reference: Fernando J. Gómez- was aimed at creating a model June in Physical Review Letters Ruiz, Jack J. Mayo, and Adolfo del that could estimate the number and was accompanied by a Campo: Full Counting Statistics of of defects and guide the optimum ‘Viewpoint’ published in Physics, Topological Defects after Crossing design of these systems. a comment on the results by the a Phase Transition. Phys. Rev. independent physicist Professor Lett 17 June 2020 To do this, the physicists used Smitha Vishveshwara from the theoretical tools to describe University of Illinois at Urbana- phase transitions and numerical Champaign. simulations to estimate the defect

UNIVERSITY OF GRONINGEN 31 In Focus Transporting energy through a single molecular nanowire by Rene Fransen (ScienceLinX)

Plants and photosynthetic bacteria catch sunlight via molecular antennas, which then transfer the energy to a reaction centre with minimal losses. Scientists would like to make molecular wires that can transfer energy just as efficiently. Scientists at the University of Groningen created tiny fibres by stacking certain molecules together. Single fibres transport energy, although they sometimes malfunction. Creating bundles of fibres (as is done with copper wiring) was thought to be the solution but this turned out not to be the case. Energy moves fast when spread out across several molecules. In single fibres, this works well but in bundled fibres, this spreading out is hampered as the molecules experience strain. These results can be used to better understand energy transport along molecular wires, which will help in the design of better wires.

Photosynthetic systems in lengths exceeding 4 micrometres a single molecule. Hildner: ‘The nature transport energy very and a diameter of just 0.005 energy is delocalized over several efficiently towards a reaction micrometres. By comparison, molecules and it can therefore centre, where it is converted into the diameter of a human hair move fast and efficiently across a useful form for the organism. is 50-100 micrometres. This the fibre.’ This delocalization Scientists have been using this system can transport energy like means that the energy moves as inspiration to learn how to the antennas in photosynthetic like a wave from one molecule transport energy efficiently in, for systems. ‘But we sometimes to the next. By contrast, without example, molecular electronics. saw that the energy transport coherence, the energy is limited Physicist Richard Hildner from became stuck in the middle of to a single molecule and must the University of Groningen and our four micrometre-long fibres. hop from one molecule to the his colleagues have investigated Something in the system appeared next. Such hopping is a much energy transport in an artificial to be unstable,’ he recalls. slower way to transport energy. system made from nanofibres. The results were published in the To improve the energy transport ‘In the bundles, coherence is lost,’ Journal of the American Chemical efficiency, Hildner and his explains Hildner. This is caused Society. colleagues created bundles of by the strain that the bundle nanofibres. ‘This is the same idea imposes on each fibre within ‘Natural photosynthetic systems as that which is used in normal it. ‘The fibres are compressed have been optimized by billions electronics: very thin copper wires and this causes side groups of of years of evolution. We have are bundled together to create the molecules to crash into each found this very difficult to copy a more robust cable.’ However, other.’ This changes the energy in artificial systems,’ explains the bundled nanofibers turned landscape. In a single fibre, the Hildner, associate professor at out to be worse at transporting energy of the excited states of the University of Groningen. In energy than single fibres. several neighbouring molecules the light-harvesting complexes are at the same level. In a bundle, of bacteria or plants, light is Coherence the local environments of the converted into energy, which is The reason for this lies in molecules differ, leading to a then transported to the reaction something called coherence. difference in energy levels. centre with minimal losses. When energy is put into the molecules that make up the Bike tour Bundles fibres, it creates an excited ‘Imagine that you are on a bike Five years ago, Hildner and his state or exciton. However, this tour. The height profile of the tour colleagues developed a system excited state is not a packet of represents the energy levels in in which disc-shaped molecules energy that is associated with the molecules that make up the were stacked into nanofibres with

32 ADVANCED MATERIALS | WINTER 2021 News fibres,’ says Hildner. ‘If you are cycling in the Netherlands, you will arrive at your destination quickly because the terrain is flat. Newsflash In contrast, in the Alps you must Prof. dr. Moniek Tromp elected vice-chair of the Young cycle uphill quite often, which Academy of Europe is tough and slows you down.’ Thus, when the molecules’ energy Prof. dr. Maria Antonietta Loi elected Fellow of American levels in the fibres are different, Physical Society transport becomes more difficult. NEVAC prize for Brian Baker of the Stöhr group This discovery means that the team’s original idea, to increase NWO XS grant for Dr. Wlodarczyk-Biegun energy transport efficiency using Prof. dr. Rudolf partner in consortium that receives H2020 bundles of nanofibres, turned out to be a failure. However, they Marie Curie ITN-ETN grant have learned valuable lessons from this, which can now be NWO KLEIN awarded to Prof. dr. George Palasantzas used by theoretical physicists JACS Spotlight on self-assembled monolayers of Prof. dr. to calculate how to optimize Chiechi and Prof. dr. Rudolf transport in molecular fibres. ‘My colleagues at the University of Prof. dr. Bart Kooi installed as Education Director of the Groningen are currently doing just Zernike Institute for Advanced Materials that. But we already know one thing: if you want good energy Herman Duim Graduate Student Award recipient for the transport in nanofibres, do not 2020 MRS Spring Meeting use bundles!’ ENW klein Grant for Prof. dr. Maxim Pchenitchnikov and Prof. dr. Thomas L.C. Jansen Imagine that you IEEE Robert E. Newnham Ferroelectrics Award for Prof. are on a bike Beatriz Noheda tour. The height Remco Havenith Nanoscience Teacher of the Year Prof. dr. Koster partner in consortium that receives H2020 profile of the tour Marie Curie ITN-ETN grant represents the Dr. Amar Kamat wins FSE’s Postdoc Prize energy levels in Annemarie Maan elected KNAW/De Jonge Academie Faces the molecules of Science that make up the Prof. dr. Petra Rudolf appointed new Dean of Graduate Studies Prof. Onck partner in ENW-GROOT project of EUR 2.7 million fibres KNG Juryprize for Björn Kriete Prof. Marrink and Dr. Jansen partners in ENW-GROOT project of EUR 2.7 million Reference: Bernd Wittmann, Felix A. Wenzel, Stephan Wiesneth, Heeres and Heeres receive Groene Groninger award Andreas T. Haedler, Markus Drechsler, Klaus Kreger, Jürgen Jan Post project leader Northern Netherlands AI Hub Köhler, E. W. Meijer, Hans-Werner Jacquelien Scherpen awarded IEEE Fellow Schmidt and Richard Hildner: Enhancing Long-Range Energy Dr. Wlodarczyk-Biegun receives second NWO XS grant Transport in Supramolecular Architectures by Tailoring Shirin Faraji Young Academy of Groningen board member Coherence Properties. J. Am. Chem. Soc. First online 11 april Bart van Wees featured in Physical Review B 50th Anniversary 2020 Milestones

UNIVERSITY OF GRONINGEN 33 In Focus CogniGron is two years along the path towards ‘human’ computers by Eelco Salverda, Communication UG

The computer: our traditional powerful machine is rapidly approaching its limits, so researchers at the UG’s CogniGron centre are working on developing the computer of the future. Two years into the project, Beatriz Noheda, director of CogniGron, takes stock. Although developing a new super- calculator is obviously a long-term project, CogniGron has already achieved a lot.

The computer of the future: it has help to prevent diseases. And cells, have thousands of mutual almost become a holy grail that merging worldwide seismographic connections and form networks is being sought by researchers data could generate insight into that can transport the information from every corner of the earth. potential earthquakes. Or take through a multitude of paths. Beatriz Noheda, Professor of ‘the internet of things’. We have Brain cells process information, Functional Nanomaterials at been talking about fridges that but at the same time they are the UG, and her colleagues from tell the supermarket when you also able to store information as the fields of materials science, run out of milk for ten years physics, mathematics, computer now. These developments have science and artificial intelligence ground to a halt because with the are working on new materials for current computer design we are the next generation of computers, unable to process all of this data.’ To take some inspired by the functioning of But this could be very different. the human brain. The current Computers may be better chess of the pressure generation is approaching the players than humans, but there limits of its capacities. ‘We need are still things that humans do off humans, to change the way in which better. computers work if we are to keep we created up with the enormous amounts The brain is an example something that of data that are generated by the Current computers send every digital world,’ explains Noheda. bit of information from transistor did not resemble ‘They cannot deal with big data to transistor, one step at a time. efficiently, and they waste a lot The human brain, however, is able a human. We of energy by doing so, forcing us to process lots of information to decide which data to process. simultaneously. This is called are now going This can and must become a more parallel processing. ‘Take this sustainable process, so that all room,’ says Noheda to illustrate. back to the of the useful information that is ‘If we sit here, you immediately drawing board, contained in the available data know what to focus on. You listen can be retrieved.’ to me and you don’t pay attention and using to, or in other words waste energy Unused data on, information regarding the humans as our Noheda gives a few examples of carpet and the chairs, for instance, data that currently goes unused. despite that this information is model. ‘Take medical data. An analysis of also being sent to your brain. We symptoms reported by patients can prioritize in a millisecond. This from all around the world could is because the neurons, our brain

34 ADVANCED MATERIALS | WINTER 2021 In Focus being a memory. Computers use two separate systems to perform Learning to understand these two tasks. This makes our each other brain highly economical in terms Noheda explains that much of energy. A computer that works Every discipline of the initial years was spent like this would be a real game generating understanding and changer.’ Scientific coordinator has its own trust. ‘A collaboration between Jasper van der Velde, who has four disciplines requires a lot of now joined us, sums it up nicely: way of working. brainstorming and discussions. ‘To take some of the pressure off What are we doing, how can we humans, we created something People think help each other? Only this way that did not resemble a human. we can effectively combine the We are now going back to the differently. You strengths of each discipline.’ drawing board, and using humans have to learn Noheda and her colleagues are as our model.’ based in Nijenborgh 4, which each other’s is the physics and chemistry The search for the building. One building further, perfect material language. you’ll find the computer scientists, We need new materials, electronic the mathematicians and the circuits and systems to be able artificial intelligence researchers. to imitate the function and They are only a few physical connectivity of neurons. It’s steps apart, but the metaphorical not quite like looking for the distance can be more difficult proverbial needle in a haystack, to span. ‘Every discipline has but it certainly isn’t easy. ‘We to broaden our horizons, but the its own way of working. People have six research groups working current generation of computers think differently,’ explains Van at the Zernike Institute for simply can’t deal with them.’ der Velde. ‘You have to learn Advanced Materials, each of What was once a modern, useful each other’s language.’ But they which is studying two or three machine is rapidly becoming the managed. A shared vision and potentially suitable materials,’ limiting factor. joint goal have helped to tear explains Noheda. ‘The material down walls and remove barriers. we are looking for must satisfy a Two productive years ‘Sharing experiences helps you to lot of conditions – and you also CogniGron has existed for two- grow,’ says Noheda. ‘It’s healthy have to take long-term availability and-a-half years now. How are to look at things from the other into account.’ things going? ‘Really well,’ Noheda side every now and then,’ she continues. ‘Over thirty professors laughs. Unique collaboration are now working on CogniGron ‘We soon realized that researchers related projects. We managed New generation of from a single field wouldn’t be to recruit ten new professors. scientists able to do everything that we They were very keen to join Working together means stepping wanted to do,’ Noheda continues. us because they are equally out of your comfort zone. This Whereas much of the research enthusiastic about our vision and can be a challenging, time- into new computers is carried out goals. In turn, CogniGron benefits consuming business. Not everyone from within one single scientific from their expertise and global is flexible enough. All newly discipline, the UG entered into contacts. They are knowledge appointed professors therefore a unique collaboration between magnets.’ And then there’s the work in more than one field; the materials scientists from the newly acquired transmission they feel comfortable in two Zernike Institute and the Bernoulli electron microscope (TEM), different worlds. In this respect, Institute for Mathematics, another flagship. There are only Noheda has high expectations Computer Science and Artificial about ten of these microscopes of the PhD students working at Intelligence. ‘The computer in the whole world, and they CogniGron, where they grow up in scientists tell us exactly what can be used to study materials a multidisciplinary environment. is needed. The mathematicians at the atomic level. ‘That is a ‘We are already seeing this with make models of the properties, very important factor,’ Van der some of our Bachelor’s and which the physicists then test on Velde stresses. ‘You have to know Master’s students. They prefer the new materials in their labs. exactly how a material works broader-based course units, Artificial intelligence researchers before you can control it and such as maths and physics, or explain what the new hardware make it work for you.’ Finally, physics and computer science. must be capable of. Algorithms CogniGron has published around CogniGron is exactly what I was developed within the field of ten important articles in leading looking for, you hear them say.’ Artificial Intelligence have proven professional journals.

UNIVERSITY OF GRONINGEN 35 News

Experimenting Ubbo Emmius Fund of the Fundamental research but with a practical goal – would that be UG receives large donation a good description of Noheda’s work? ‘Yes, indeed,’ she nods, ‘because that computer is still from alumnus a long way off. No, that’s not frustrating. It’s all about the Extra source of funds for ongoing learning process. We saw that we were getting closer academic research after just six months. We’re happy with every step in the right direction.’ HP, IBM, Intel; A former student has donated a they are all following CogniGron large sum via the Ubbo Emmius with great interest. These Fund to their alma mater, the are the companies that will University of Groningen (UG). At ultimately be manufacturing the end of October, as part of this the computers. ‘We work closely donation, the Ubbo Emmius Fund with companies like these but received a sum of €35 million. they can’t diversify in their It is expected that further sums research as much as we can. will be received as part of this Prof Beatriz Noheda (right) Companies need to sell products donation in the near future. The and earn money. Researchers final donation amount is currently Engineering, researchers have can be more adventurous, and unknown because this depends been working on developing try bolder ideas.’ She is echoing on the return on the investments materials for the next generation Nobel Prizewinner Ben Feringa’s from which the donation was of computers since 2018. words: ‘Let universities be made. The donor has asked to playgrounds’. ‘Our mindset is remain anonymous; the UG and ‘It is important research because broader,’ adds Van der Velde. Ubbo Emmius Fund are respecting the demand made of computers ‘Some materials work best this wish. to process and interpret enormous at extreme temperatures. A amounts of data will increase company won’t investigate this, According to the conditions explosively over the coming as the temperature would be too attached to the donation, the years. At the UG, we can explore high for commercial purposes. funds must be used for scientific solutions to this challenge with a So that’s what we do. And if a research at the UG. President of strong, multidisciplinary project material turns out to work, we the Board of the University, Prof. comprising scientists from various start looking for workability at Jouke de Vries: ‘We are happy disciplines. To show our thanks a more feasible temperature.’ and thankful for this enormous donation to the Ubbo Emmius for this donation, we wanted to Trendsetter Fund. Never in our history has name CogniGron after the donor. But, of course, we are respecting The multidisciplinary character such a great sum been left to their wish for anonymity’, states of CogniGron also has a the University by an alumnus for Prof Beatriz Noheda, Director of disadvantage. Research the benefit of scientific research. CogniGron. findings take longer to It offers us the opportunity to substantially invest in fundamental generate and are more Fund difficult to publish as they and applied research. In addition, The donation is being managed fall outside the scope of field- we will be able to give ambitious by the Ubbo Emmius Fund. The specific scientific journals. early-career academics the chance Fund supervises the careful and But this hurdle is also being to further shape their scientific correct allocation of donations in cleared. A new journal recently careers.’ accordance with any conditions appeared: Neuromorphic stipulated by donors. The intent computing and engineering. €30 million for is to deposit this donation into Three CogniGron researchers CogniGron a so-called endowment fund, in are closely involved in this The donor selected the first which annual returns are paid journal, which just goes to recipient for part of the donation: out every year. In this way, the show how things in academia the Groningen Cognitive Systems UG is ensured of a long-term, are changing. And maybe and Materials Center (CogniGron), substantial extra source of income how much of a trendsetter which will receive a sum of to benefit scientific research and CogniGron is. €30 million. Under this project at the Faculty of Science and PhD positions.

36 ADVANCED MATERIALS | WINTER 2021 News Virus assembly has been filmed Spanish and Dutch researchers discovered how the HIV/AIDS virus is formed

Scientists in Groningen and Madrid have managed to capture unique images of the first steps of virus assembly. By using a very fast scanning probe microscope, they were able to film how HIV proteins begin to form a virus. It appears that the virus forming process does not proceed in a very orderly manner. At first sight, it seems very haphazard. Still, this process eventually leads to a regular virus particle. By figuring out how virus assembly takes place, research can be done in a more focused manner into anti-viral medicines that specifically hinder the forming of the virus.

Human immunodeficiency virus of the high-speed microscope (HIV) causes AIDS, a disease in their lab, it became possible that still results in the deaths to follow virus assembly in real of over half a million people time. ‘A technical masterpiece’, per year. HIV packages viral exclaims Prof. Wouter Roos. genetic material into a capsule containing virus proteins, among Completing the puzzle other things. While highly clear The researchers demonstrated images have been taken with an that virus assembly does not electron microscope that show proceed in a very ordered how the proteins are bound to one manner at all. It appears more another, until recently, no methods like completing a jigsaw puzzle, have been able to demonstrate in which puzzle pieces are added Single molecules building how they bind together. After at different spots but also taken all, electron microscopes away again if they do not appear from the creation of the individual cannot capture moving images. to fit. In this way, the process building blocks at the start, to the However, a very fast atomic force seems like an apparently formation of a whole infectious microscope recently entered the haphazard coming and going of virus particle. As well as providing market: the High Speed Atomic proteins, with some sort logic fundamental insights into the Force Microscope (HS-AFM), with hidden beneath this. Finally, biology of viruses, this work which videos can be made. This an ordered grid of proteins is also has functional applications. microscope has made it possible created, which forms the basis Once it is clear how virus particles to study molecular processes by of the virus particle. It is likely are made up, highly targeted touch , but scientists had not that other viruses use a similar research can then be done into yet succeeded in following the process to build virus particles. anti-viral medicines that focus on incredibly dynamic process of interrupting the assembly of the virus assembly. Coronavirus AIDS virus. At a later stage, it is The results of the research have also hoped that these methods Through intensive collaboration been published in scientific journal can be used to investigate other between a research group ACS Nano. Now that it is clear how viruses, such as the coronavirus specializing in HIV at the the first stages of virus forming strain that caused the outbreak Universidad Autónoma de Madrid take place, the researchers from of COVID-19. and the Molecular Biophysics Groningen and Spain want to research group led by Prof. shed light on the next steps. In Wouter Roos at the University this way, they hope to create a of Groningen, who have a version complete image of the process,

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