Picture of the month

Picture of the Month: From the inside of friction

Without friction, nothing works in our everyday life. Sometimes friction is vital, as in vehicle braking, sometimes it is undesirable, as when the bicycle rolls out and we have to pedal again. Such frictional forces still cannot be accurately calculated or predicted. This gap in our knowledge has lasted for an astonishingly long time. Research into the prediction of friction has been going on since Leonardo da Vinci. Professor Georg-Peter Ostermeyer of the Institute of Dynamics and Vibrations would like to shed more light on the darkness of the phenomena of friction with an innovative machine, which can be seen in the picture of the month. His machine, which was completely new for basic research, makes it possible to see in situ inside the frictional contact between two bodies. The frictional interface reveals surprisingly complex dynamics of wave motion and wear particle flow. Cork particles moving in an almost dancing fashion are exemplified in the image. The machine makes it possible to observe the complex self-organization effects and thus contribute significantly to the clarification of different phenomena of friction, wear and the origin of friction dust emissions.

Among other things, the Wear Debris Investigator machine designed by Professor Ostermeyer is intended to provide answers to questions about the frictional force of brakes. Picture credits: Max Fuhrmann

Although friction is ubiquitous, friction is still not understood causally. We have been using friction and its effects since time immemorial. In the Stone Age, our ancestors made fire with wood rubbed against each other. Even today, friction is used to make fire. The ancient Egyptians also moved large stone blocks over long distances using roller beams that were probably oiled. We also still use these techniques today to minimize drag forces. Friction is sometimes desirable and sometimes not. On the one hand, there is no walking, running or rolling without friction, as you can easily see on a frozen lake. Here, only very small steps or accelerations are possible. But on the other hand, friction is also responsible for an incredible amount of energy destruction in our world, because the functionality of many processes and machines contains friction as an unwanted and unavoidable by-product, which has to be served energetically.

Artificial wear particles between soft cork and hard glass in Wear Debris Investigator. Picture credits: Kristina Rottig/TU Braunschweig

In the mid-15th century, Leonardo da Vinci was probably the first scientist to set out basic properties of friction in experimental sketches. Although a great many experiments, explanations and results have been generated since then, the very simple Coulomb’s law of friction for the elementary states of adhesion and sliding is still often used in simulation and system description today. This law for dry friction gives quite good results when one has approximate point contacts and friction does not dominate the system events energetically or phenomenologically.

Better predictions of friction needed

Mathematical and computational developments in recent decades have enabled system dynamics to develop increasingly accurate mathematical representations of machines and processes, known as digital twins. The aim is to use these virtual functional copies of real systems as cost-effective substitutes for real processes that pose a risk to health or for expensive hardware developments in early development phases. However, this is only possible if the model’s behavior is sufficiently close to reality in terms of the questions it is asked.

This already works fascinatingly well. Apart from the mathematical-informatic side, the background is that all elementary especially mechanical forces except friction are well understood. These can be measured very well. They are used, usually combined with each other and coupled with non-mechanical quantities, to provide increasingly accurate system predictions in many areas of our daily lives. System dynamics has therefore taken off on an unprecedented triumphant march, especially in the last few decades. Among other things, these elementary forces enable simulation kits that allow even non-experts to build digital twins.

However, the complexity of nonlinear dynamics such as self-organization, chaos and turbulence, as well as the nature of the last unknown elementary force of mechanics, friction, are the limits of this approach.

Still no complete scientific explanation of the friction force in brakes

This is particularly evident in tribological high-load contacts such as brakes. Brakes consist of discs or drums against which pads are pressed. The linings themselves consist of up to 20 different ingredients, usually bound in resin. The friction pairings must generate high frictional forces at all times, but at the same time should have a long service life. The development of the linings is a well-kept secret of the companies. It is defined almost exclusively by trial and error. A causal scientific explanation of the friction force from the ingredients and the resulting mechanical, thermal and chemical reactions does not even exist to this day. Why the frictional force differs at different times under otherwise exactly the same conditions is only now beginning to be understood. The wear dust in the friction boundary layer forms temporary additional friction surfaces, which essentially store the short-term load history of the brake. Another issue in focus today is the emitted brake wear dust, which shapes a vehicle’s emissions signature as engine emissions continue to decline. Together with some tire wear, they form long-lived and sometimes respirable pollutants in the air.

Aiming to reduce emissions

How can brake emissions in the city be reduced through meaningful braking actions and traffic control measures to more effectively protect residents, for example? How must the material structure of brake pads be changed so that emissions are less harmful to health?

These questions are completely open. The machine in the picture of the month is intended to provide initial answers.


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Pictures of previous months

Picture of the month August 2021

Screenshot of the web portal visualize.numid.online. Digitized copies of around 30,000 coins from university coin collections, sorted by minting date: a fascinating insight into 2,600 years of monetary history. Picture credits: Johannes Wienand/TU Braunschweig

If Scrooge McDuck were a historian, he’d have a blast with this pile of coins: a massive mountain of coins, carefully aligned along a timeline that stretches from the beginnings of coinage in the seventh century BC to the present day. The assemblage spans from early electron money, the first coins ever minted, through the Greek silver coinage of the classical and Hellenistic periods, then through Roman aces, sestertii and denarii, on to late antique and Byzantine gold coins, Islamic dirhams and medieval bracteates, and on to modern medals and coins from our own time. This special kind of treasure has been compiled by a network of university coin collections. Each individual coin, which is arranged here according to its minting date, is based on a sophisticated digital recording and description of the respective original object. More than 30 German universities are working together to digitize their coin collections in a scientifically based way for research and teaching. The digitized individual objects then flow together on the portal visualize.numid.online, among others. The screenshot of the chronologically sorted pile of coins comes from there. Here, anyone can rearrange the approximately 30,000 coins at random – for example, by mint, material, weight, diameter – and thus gain ever new fascinating insights into the valuable holdings of the university coin collections in Germany. Each individual coin can be selected individually. A mouse click takes the user to the digital coin cabinet of the respective collection of origin, where all relevant detailed information on the selected object is stored. For example, you can also access a coin of the Roman Emperor Constantine, which is in the collection of TU Braunschweig. The digitization network providing the data is called “Network of University Coin Collections in Germany” NUMiD. Such an association is so far unique in the world. The research and digitization network was founded by Professor Johannes Wienand, who is responsible for the history of Greek and Roman antiquity at TU Braunschweig and who also heads the coin collection at the Herzog Anton Ulrich Museum. The database family, which the university collections have joined, now spans universities and museums in four European countries. About 100,000 objects are brought together in this way. They are jointly searchable via the portal ikmk.net – about one third of the data was compiled within the NUMiD network.

“The willingness of such a large number of collaborative partners to embark on this joint scientific adventure is the crucial prerequisite for the success of the project, and the support of the Numismatic Collection of the National Museums in Berlin as a non-university collaborative partner provides the necessary institutional stability,” says Johannes Wienand. The historically and materially valuable original objects are photographed, identified and described in the university institutes to which the collections belong by staff or, in the context of courses, also by students; for the creation and publication of the digitized material, the collections use a common database system and a common pool of standardized concepts (norm data). Interfaces enable the export of data to international research portals. Statistical evaluations and Big Data analyses are then possible there. The possibility of data visualization via the visualize portal is basically just a byproduct of digitization at the network – albeit a very appealing one. “The main goal is to make the collections accessible for research,” says Professor Wienand. The basis (in addition to high-quality front and back photos) is a scientifically valid documentation of the objects – their material properties, their geographical, chronological and political location, their image and text programs, and their provenances.

Picture of the month July 2021

An electric arc in the lightning protection laboratory of the elenia Institute for High Voltage Technology and Power Systems. Picture credits: Max Fuhrmann/TU Braunschweig

Our picture of the month captures the split seconds that decide the lives of people, but also devices such as refrigerators and computers, when lightning strikes. The extremely hot plasma in the photographed spark gap can be the saving short circuit for people and devices. The white and colored squares at the bottom of the picture come from the high-speed camera in the lightning protection laboratory of the elenia Institute for High Voltage Technology and Power Systems. Doctoral student Enno Peters uses it to research what effectively protects against lightning damage. The lightning protection system distinguishes between external and internal lightning protection. On the outside, lightning rods, connected to the grounding system, protect the building structure. Thus, lightning is more likely to strike the intercepting rod, whereupon the external lightning protection can discharge it to ground in a controlled manner. Inside the building, despite lightning rods, the risk of surge remains. “When lightning strikes the external system, it generates high currents and voltages. Normal insulation has little to counter the extraordinarily high lightning current and the resulting high voltage. Everything that is then still plugged into the socket would be toast. Moreover, this does not only apply to strikes directly at the house. Even if there is lightning within several kilometers, this can lead to overvoltage in the buildings,” explains doctoral student Enno Peters.

Lightning current arresters, which at their core consist of a so-called spark gap, help against the high-energy lightning current. It contains two electrodes separated by air. When lightning abruptly drives up current and voltage, the air becomes plasma and thus conductive. An electric arc forms, similar to that of some welders. This arc can be the saving short-circuit. The picture of the month shows such an arc of plasma in a spark gap in the lightning current laboratory. The spark gap, which is about the size of a fist, is hardly any different from those protecting industrial buildings or private homes. Only on one side is the hull material made of a transparent plastic so that the high-speed camera can photograph into it. “The German Research Foundation (DFG) was a great help with the camera,” says Enno Peters. “Since the flash is only in the spark gap for a few microseconds, we needed an extremely fast camera. Ours manages 800,000 frames per second. So with that, we get about ten images of each arc.” To better analyze the black and white camera images, PhD students Benjamin Weber and Enno Peters programmed an analysis software together. This marks the current distribution with a color code: The redder, the higher the current. At the same time, it immediately recognizes the relevant area of the arc (red box) and creates line profiles that indicate the current density per pixel across the current flow (yellow line and diagram). The research shall reveal how the plasma is distributed locally in the spark gap. “Several tens of thousands of amperes, temperatures up to 30,000 Kelvin and a pressure of over 500 bar: Even a lightning current arrester can’t withstand that too often. As side effects, if we know the distribution of the plasma, we can make statements about material burnup at the electrodes and combustion chamber. Another open question is how the device returns to its initial state. With this knowledge, the devices could be improved even further in the long term,” says Enno Peters.

Picture of the month June 2021

Among other things, this year’s TU Night will take visitors to an air raid shelter, a lost place in the Okerhochhaus. Picture credits: Kristina Rottig/TU Braunschweig

It is cold in the long, narrow corridors with thick concrete walls. Glaring neon lights illuminate the bare walls, with no end in sight. A cool breeze drifts through the labyrinth. Not for the timid or those with claustrophobia. A lost place at the TU Braunschweig in the middle of the Central Campus, or rather under the Central Campus. This year’s focus topic of the TU Night also leads into the air-raid shelter of the Okerhochhaus in Pockelsstraße 3. Due to Corona, the TU Night cannot take place on campus this year. Therefore, it is necessary to go new ways. From June 7 to July 3, the digital format offers the opportunity to discover places at the TU Braunschweig that have lost their function, interactively and with videos. With current research topics, on the themes of mobility, waste and happiness, musically and culturally accompanied, they are re-played and brought back to life. The program of the TU-Night lives from its contrasts: Abandoned or closed “Lost Places” are combined with “Future Talks” by scientists on the topics of sustainability, urban development and universities in times of Corona as well as shoulder views on places of current research at the TU Braunschweig open up new perspectives. The Okerhochhaus is a 17-story disk-like high-rise building with a depth of only ten meters, designed by the architect and university lecturer Dietrich Oesterlen and built between 1958 and 1960. Today, it houses most of the institutes of the Department of Architecture. It is part of the building ensemble Universitätsplatz, which can be attributed to the “Braunschweig School”. In the second basement of the Okerhochhaus, which is also called “Scheibe”, is the air-raid shelter. This also served research purposes. Except for a small part used as an archive, the air-raid shelter is empty today. Information and the program can be found on the TU-Night website.

Picture of the month May 2021

Making sand vibrate: Chladnic sound figures generated in the acoustics lab at TU Braunschweig. Picture credits: Max Fuhrmann/TU Braunschweig

How can you visualize the vibration behavior of plate structures without simulations and without laser measurement technology? With a relatively simple experiment. In the 18th century, vibration behavior was studied thanks to a discovery by the German physicist Ernst Florens Friedrich Chladni. The experiment is also on display for teaching purposes in the acoustics lab at TU Braunschweig, which works closely with various institutes and with the Cluster of Excellence SE2A. Sebastian Rothe, head of the “InALab Acoustic Engineering”, explains how the impressive patterns are created. The vibration behavior of structures describes in which areas much or little vibration occurs at certain frequencies. Knowledge of this helps to avoid noise (low-noise design) or to set a desired vibration behavior (acoustic design). With the Chladni figures, it has been possible to visually assess the vibration behavior since more than 200 years ago. “Today, we only use this experiment for teaching purposes, as it gives students an understanding of basic acoustics in a very vivid way. We can use it to make sound visible,” says Sebastian Rothe.

But how can sound be made visible? To do so, the center of the plate is made to vibrate at a mono-frequency. “If a natural frequency of the plate is hit (resonance), the operating vibration mode is mainly determined by the associated natural mode. Put simply, standing waves with areas of high and low vibration amplitude form on the plate,” Rothe explains. While the sand is catapulted away in areas with high vibration amplitude, it collects in the areas with low vibration amplitude. In this way, the operating vibration modes can be made visible. Each resonant frequency has a characteristic operating mode shape. The resulting patterns are called ” Chladni figures”. Where these resonant frequencies lie depends on the geometry and material of the panel. The Acoustics Laboratory is concerned with the experimental characterization of the airborne and structure-borne sound behavior of solids. Mainly, structure-borne sound investigations and material characterizations are performed. “For instance, we use laser measurement technology to measure the distribution of the sound velocity of surfaces of vibrationally excited structures and match it with simulation data, for example,” says Rothe. Another important part, he says, is determining frequency-dependent material parameters such as damping (can a material dampen sound well or poorly?) or the elastic modulus of materials (how stiffly does a material react when subjected to force?). The absorption coefficient, i.e. how much sound is “swallowed”, as well as the flow resistance of porous media (e.g. metal foams, plastic foams) are also measured so that these data can in turn be used in simulations.

Picture of the month April 2021

They look like lots of colourful Easter eggs: the epithelial cells under super-resolution fluorescence microscopy. The picture of the month April shows an epithelial cell culture infected with influenza A viruses. Influenza A is considered the most dangerous type of influenza virus, responsible for severe pandemics and epidemics with many deaths. The picture was taken by Professor Sieben, head of the Nanoscale Infection Biology research group at the Helmholtz Centre for Infection Research and junior professor for cell biology of viral infections at the Technische Universität Braunschweig. The group uses special microscopy techniques to learn more about how viruses work and function, and thus how infections can be prevented. Epithelial cells can grow together to form a dense two-dimensional epithelium in which all cells seem to look identical. However, fluorescence microscopy shows that no two cells are alike. Influenza A viruses infect alveolar epithelial cells, so-called pneumocytes, among others in the lungs. The picture shows human A549 cells, a model cell line for human pneumocytes of type 2. The cells were infected with influenza A viruses and chemically fixated after about eight hours. To then detect the infection, the cells were treated with an antibody that binds the viral nucleoprotein (green). The nucleoprotein is an important component of the influenza genome, which in turn is amplified in the cell nucleus. This leads to a strong accumulation of the nucleoprotein in the cell nucleus. In order to recognise the cell nucleus itself under the microscope, the DNA is marked with the dye DAPI (blue). In addition, the actin cytoskeleton, the protein network of thin, thread-like cell structures, is marked with a dye to identify the cell boundaries (red). In this experiment, which is shown in the picture, it was examined how much the development of the infection differs from cell to cell. Although all cells were infected with approximately the same amount of virus, very strong differences can be seen between the cells. “We are working on quantifying these effects and identifying their causes so that we can understand why individual cells seem to cope better with infection,” says Professor Sieben. To do this, his research group analyses the images on the computer. The labelling of the cellular structures (DNA and actin) enables the scientists to better identify the cells or the cell nucleus and thus precisely determine the amount of nucleoprotein produced per cell and even per cell nucleus.

Picture of the month March 2021

Microfluidic system as used at the Institute of Microtechnology (IMT). Picture Credit: Peer Erfle/TU Braunschweig, Germany.

The picture shows a microscopic mixing channel for the production of nanoparticles as carriers for sparingly water-soluble active ingredients. The advantage of these carrier systems: As a result, the active ingredients can be better absorbed by the body or administered bypassing the gastrointestinal tract. The Institute of Microtechnology is conducting research into systems for producing nanoparticles with adjustable properties and a particularly narrow size distribution. In contrast to classical methods, microfluidics offers maximum control over the mixing process that creates the nanoparticles. Pharmaceutically relevant nanoparticles have already been produced in cooperation with the Department of Pharmaceutics (Professor Heike Bunjes and Juliane Riewe). The channel of the microsystem with injection nozzle and mixing elements was printed onto a glass substrate using a super high-resolution 3D printing process (2-photon polymerization). The channel has an inner diameter of 0.2 millimeters. The image was taken during a mixing experiment in which water and blue-colored ethanol were passed through the system. The blue-dyed stream connects to the main stream through an injection nozzle with an inner diameter of 30 micrometers. The 3D structure of the mixing elements increases the contact area between the two streams. This intensifies diffusion for faster mixing of the solutions. The special feature of this new microsystem is that the 3D structures prevent lipid contained in the ethanol from coming into contact with the channel walls and sticking to them. This so-called fouling has been an unsolved problem in the production of nanoparticles in microfluidic systems. Fouling causes flows and mixing processes to become unstable, and the system can become clogged. The lipid nanoparticles produced, ranging in size from 70 to 200 nanometers, also provide an option for injectable aqueous solutions of an active ingredient.

Picture of the month February 2021

Saint John’s wort is one of the most studied medicinal plants. Picture credits: Ludger Beerhues/TU Braunschweig

Our picture of the month February shines in bright yellow and brings color into the gray winter month. It comes from the Institute of Pharmaceutical Biology and shows the flower of St. John’s wort. Clinical studies show that extracts from the plant can alleviate mild to moderate depression. The substance hyperforin is primarily responsible for the effectiveness. Professor Ludger Beerhues and his research group are investigating how this substance can be biotechnologically produced in the laboratory. St. John’s wort is one of the most studied medicinal plants. It has antibacterial as well as anti-inflammatory effects and is therefore used for wound healing. It also contains the pigment hypericin. This is exuded as a red juice when rubbing the petals between the fingers. Hypericin is currently being studied in connection with the treatment of various types of tumors. St. John’s wort is also known to many for its effect as an antidepressant for mild to moderate depression. The active ingredient that comes into play here is called hyperforin. Hyperforin, along with essential oil, is stored in rounded containers in the leaves. These spheres are so large that they span the entire leaf. In backlighting, they are clearly visible as translucent dots. In addition to the medicinal plant, St. John’s wort, there are about 500 other St. John’s herbs worldwide. They all contain hyperforin-like components. Chemically, these constituents are very complicated and therefore difficult to reproduce in the laboratory. In the plants themselves, they are present only in low concentrations. Therefore, it is a challenge to obtain sufficient amounts of the hyperforin-like substances from the various St. John’s wort plants. However, these are needed to perform extensive biological tests with them or to enhance the pharmaceutical effects by modifying the substances. For this reason, Professor Beerhues and his team are pursuing a biotechnological approach: “We are working on replicating the biosynthetic pathways of the active substances of St. John’s wort in microorganisms. This is how we want to achieve higher yields.” To do this, they first need to investigate how exactly St. John’s wort produces its complex ingredients. These biosynthetic pathways – that is, the path from the individual building blocks to the active ingredient – are relatively long. The individual steps are supported by various enzymes. The researchers have to identify the genes for these enzymes so that they can then transfer them into microorganisms and string them together. The challenge here is that some of the enzymes involved are bound to the chloroplasts in St. John’s wort, where photosynthesis takes place. Microorganisms, however, do not have chloroplasts, so the team has to find alternative solutions for a functioning arrangement. At the same time, the researchers have to integrate the introduced biosynthetic pathway into the basic metabolism of the microorganisms.

Picture of the month January 2021

Scientists from the Computer Graphics Lab use the ICG Dome, a large projection dome on the North Campus, to explore visual perception. Picture credit: Max Fuhrmann/TU Braunschweig

A sky filled not with stars, but with orange cubes – this is what our Picture of the Month January resembles at first glance. In reality, however, it shows the interior of the ICG Dome, a five-meter hemisphere equipped with projectors at the Computer Graphics Lab (ICG) of the TU Braunschweig. The projection dome is located in a specially equipped room on the North Campus. Like a large dome-shaped tent, the projection surface of the ICG Dome extends from floor to ceiling. Six video projectors are mounted on the perimeter and project more than 20 million pixels onto the surface. In addition, the dome is equipped with a real-time motion detection and eye-tracking system. This allows researchers at the Computer Graphics Lab to study the human visual system for various virtual reality (VR) applications. In doing so, they have to consider two different forms of vision. If we fixate a word in a text with our eyes, that term appears sharp, while the text around it appears blurry. This distinguishes foveal from peripheral vision. In foveal vision, we look straight ahead, directly at the perceived object. Peripheral vision is what we perceive from the “corner of the eye,” that is, everything outside the fixed point. This difference in vision is important for various technologies, including so-called head-mounted displays such as VR goggles. These are devices worn on the head that project images either onto a screen near the eye or directly onto the retina. In such applications, computer graphics algorithms must simultaneously take into account consciously perceived foveal vision and also the peripheral field of view, which is usually perceived subconsciously. The scientists are using the ICG Dome, among other things, to investigate how to optimally achieve this. Compared to current VR goggles, it has a significantly higher resolution.  As a result, the algorithms can be developed for current, but also for future devices. Using 3D glasses and a suit equipped with sensors, the researchers can track the gaze and movements of people located under the projection dome. In this way, they are investigating how to improve the perceived visual quality in VR applications, reduce computation time, and influence the perception of in-situ atmosphere. At the same time, they can explore scenarios for VR environments where multiple people interact with each other.

Picture of the month December 2020

A wafer with micro LED chips. Each square is a chip. Picture credits: Jan Gülink/TU Braunschweig

The picture of the month December shows a so-called ‘wafer’. Every person reading this sentence probably owns one of the square cookie crumbs. This is because chips the core of every electronic system – from smartphones to cars to washing machines – are created on wafers. However, the wafer in the picture is a very special specimen: a template for quantum computers. Quantum computers need many small and simultaneously precise light sources. At least if you want to build an ion trap computer, such as the Quantum Valley Lower Saxony (QVLS) – a research consortium including the TU Braunschweig, the Physikalisch-Technische Bundesanstalt and the Leibniz University of Hanover – is planning. The light controls the so-called qubits, the smallest computing units of the quantum computer. Each qubit gets its own light source. With a QVLS target of 50 qubits by 2025, 50 light sources are therefore required – and this within the space of this letter: Q. The picture of the month shows the pioneer for the light chip of the future quantum computer, a wafer with micro LED chips. The LED platforms already meet many of the requirements: They consist of the right semiconductor material, accommodate sufficient light sources in a small space and are potentially suitable for mass production. In fact, the image of the quantum computer wafer would look exactly like the picture of the month to humans. Only under the microscope would the difference be visible. All this is backed by many years of expertise. For example, the Institute of Semiconductor Technology with its “Epitaxy Competence Center – ec²” has all the equipment needed to manufacture chips. In addition, the QuantumFrontiers cluster of excellence, with research groups such as ‘Nano Light’, performs basic research that now benefits the quantum computer. For a quantum computer, however, the LED chips must be further developed. Their light scatters too much in the width and the wavelength is ‘only’ accurate to a few nanometers. Therefore, the scientists at the research consortium have to focus the LEDs into lasers: Micro-LEDs will then become so-called surface emitters. To turn LED light into laser light, several mirrors inside the chip manipulate the light until only a very narrow beam of a precisely defined wavelength is left. These optical components are applied directly in the manufacturing process in several layers to the wafer of the light-emitting LED. Each layer is just one hundred nanometers thick, adapted to the desired wavelength. This is so small that only the high-resolution electron microscope TEM can adequately inspect the mirrors. It’s a good thing that the microscope is available only 100 meters away, in the Laboratory for Emerging Nanometrology (LENA). To ensure that the correct wafers for quantum computers are produced at the Institute of Semiconductor Technology (IHT) at TU Braunschweig, scientists from the various disciplines of QVLS have to act in concert. For example, precision lasers are already available at Leibniz Universität Hannover, but only as laboratory setups. The goal at IHT is therefore to realize lasers on a chip size and thus make them scalable. The integration into the planned quantum computer, on the other hand, will not be possible without the expertise of the Physikalisch-Technische Bundesanstalt in the field of sensitive qubits.

Picture of the month November 2020

The Braunschweig School a Site: the architecture pavilion in the inner courtyard of the Altgebäude. Picture credits: Heiko Jacobs/TU Braunschweig

Former architecture students affectionately refer to it as the “pickle jar”: the architecture pavilion in the inner courtyard of the Altgebäude of Technische Universität Braunschweig. It was built on the initiative of the former head of the Institute for Building Design, Professor Meinhard von Gerkan. This year the building already celebrated its 20th birthday. Time to take a closer look at the pavilion in our picture of the month series. “The Braunschweig School a Site” – This was the title under which the then President Professor Jochen Litterst and former President Professor Bernd Rebe opened the architecture pavilion on 26 June 2000. A place in a central location on the campus for events and exhibitions. And for this purpose, it was actively used by the Department of Architecture, but also by other faculties and institutions of the TU Carolo-Wilhelmina before the Corona pandemic: for lectures, awards, Bachelor and Master presentations, architecture exhibitions, presentations during the TU Night. The pavilion cost 1.75 million marks and was financed by the TU Braunschweig, the Braunschweig Cultural Heritage Foundation and a donation from Professor Meinhard von Gerkan. The design was created by him, Gerkan, and his colleagues at the Institute: Christiane Kraatz, Patrik Dierks, Peter Glaser, Hans Joachim Paap and Wilhelm Springmeier. It is a light cube made of exposed concrete, steel and glass with a floor area of 15 by 15 metres. A footbridge from the stair landing of the Altgebäude leads to the gallery level of the pavilion. An open staircase leads down to the green inner courtyard, so that the outside space can be included in events. A mobile exhibition system with 56 display boards and 280 square metres of hanging space allows for a variety of uses. “A house entirely at the service of what is to take place in it. The setting is correspondingly unobtrusive”, writes the Braunschweiger Zeitung on 17 May 2000: “It is an architecture that has its own atmosphere in the transition from natural light to artificial lighting”. And indeed, the exterior of the pavilion with its façade of glass panels changes according to the time of day and the incidence of light.

Picture of the month October 2020

Topographic map of an etched semiconductor crystal, taken with a laser scanning microscope in the Institute of Semiconductor Technology. Picture credits: Klaas Strempel/TU Braunschweig

From red to yellow to blue: for 40 hours, doctoral student Klaas Strempel from the Institute of Semiconductor Technology etched a gallium nitride semiconductor crystal with hot potash lye. He uses it to investigate how the etching speed of the lye depends on the symmetrical crystal structure. Starting from the yellow plateau, three micrometer deep canyons now extend into the semiconductor – the bluer, the deeper. What looks like sunlight, on the other hand, are the up to one micrometre thin webs of gallium nitride, or what is left of it after the long etching process. Such so-called fins are further processed at the institute into microscopic transistors. Gallium nitride fins are regarded as the key to a new generation of transistors in microelectronics. In comparison to the predominantly used silicon, gallium nitride can process higher frequencies at high power. The quality of the etched surfaces is particularly important. Therefore, scientists at the Institute of Semiconductor Technology are trying to better understand the etching process. The symmetrical pattern of the image results from the regular hexagonal crystal structure of gallium nitride. Depending on the crystal direction, the potash solution eats through the fins of the semiconductor structures at only 1 to 100 atomic lengths per hour. In the process, the webs are dissolved ever thinner or even altogether. Where the rays are uninterrupted, the crystal structure is most inaccessible to the lye. The symmetry shows how this crystal structure is repeated every 60 degrees. The image is basically the topographic map of an etched semiconductor crystal, taken with a laser scanning microscope. Unlike other optical microscopes, the laser scanner works confocally. This means that it does not illuminate the whole specimen at once, but scans the object pixel by pixel and focal plane by focal plane. Knowing how much light is reflected by each pixel at all focal planes allows the construction of a three-dimensional image with height information, accurate to about 10 nanometres. By way of comparison, the smallest bacteria are 30 times larger, but to peek out of one of the trenches, they would have to be stacked at least ten high.

Picture of the month September 2020

“Flower” of the diatom Acanthoceras zachariasii in Braunschweig’s Spielmannsteich at 400x magnification. Picture credits: Anja Schwarz/TU Braunschweig

The picture of the month September is a surprise for the scientists of the Institute of Geosystems and Bioindication (IGeo) of Technische Universität Braunschweig: In a recently taken water sample from the Braunschweig Spielmannsteich a mass development, a so-called “flower”, of the diatom Acanthoceras zachariasii can be seen. It was photographed by Dr. Anja Schwarz, a research assistant at IGeo, using a Zeiss research microscope at 400x magnification. The picture of the month September is a surprise for the scientists of the Institute of Geosystems and Bioindication (IGeo) of Technische Universität Braunschweig: In a recently taken water sample from the Braunschweig Spielmannsteich a mass development, a so-called “flower”, of the diatom Acanthoceras zachariasii can be seen. It was photographed by Dr. Anja Schwarz, a research assistant at IGeo, using a Zeiss research microscope at 400x magnification. This diatom species is a locally common form of plankton, especially in eutrophic, i.e. nutrient-rich, waters. The fact that the species lives in plankton, i.e. in open water, can even be observed: Its cell wall is extremely delicate in order to keep its weight as low as possible and thus increase the length of stay in the light-flooded, nutrient-rich zone. Four long floating appendages also ensure that sinking is prevented as far as possible. This is because diatoms do not form flagella that help them counteract the downward drift into darkness. In addition, the floating appendages make them rather unpopular with predators, as they are simply more difficult to eat. But what is so surprising about the Acanthoceras flower? The polytrophic – very nutrient-rich – Spielmannsteich, in which the alga was found, has been showing massive cyanobacterial development all year round for many years due to the high nutrient load. This leads to a strong cloudiness of the water and a constant species impoverishment. Since 2013, students have been studying the water regularly as part of internships, supervised by IGeo. The picture is always the same: a cyanobacteria dominance, even in the cool seasons, which is rather untypical for cyanobacteria. In a project in which the IGeo is involved, an attempt has been made since 2018 to use ultrasound to stem the development of cyanobacteria. So far, however, without clearly visible success. In May of this year, the well-known pattern emerged, a cyanobacteria dominance with well over 90 percent share of total phytoplankton. For the IGeo researchers, the diatoms are now a first “ray of hope”. But does this also mean: Project successful – all is well? This conclusion would come much too early, says Dr. Anja Schwarz. “It is possible that the cyanobacteria have only briefly proved to be weaker than the diatoms in the competition for resources.” Further sampling should now clarify how sustainable the observed development is and whether the changes in phytoplankton composition, which have already led to a better Secchi depth, indicate a permanent limitation of the cyanobacteria in the Spielmannsteich.


Picture of the month August 2020

The leaves of Salvia officinalis contain various active ingredients. Picture credits: Markus Hörster/TU Braunschweig

Oblong, grey-green leaves and a spicy, aromatic scent are characteristic of the plant that can be seen in our picture of the month August. The common sage, or Salvia officinalis, grows in the Medicinal Plant Garden of the Institute for Pharmaceutical Biology at Technische Universität Braunschweig. It is one of about 200 species of medicinal plants cultivated there. Medicinal plants are plants that have a scientifically proven effect. “They are used in so-called phytotherapy, or herbal medicine, as components of herbal medicines,” explains Dr. Rainer Lindigkeit, pharmacist and scientific director of the Medicinal Plant Garden. The effect of sage has been known since ancient times. The plant originates from the Mediterranean region and was an integral part of medieval monastery gardens in Germany. The leaves of the sage contain various active ingredients such as essential oil, lamiacea tanning agents and flavonoids. Sage extracts have anti-inflammatory and bactericidal effects. They are used, for example, as a solution for gargling in cases of inflammation in the mouth and throat area. The dried leaves are also used for the preparation of teas, which are used against excessive sweating and for light gastrointestinal problems. Location plays a special role for medicinal plants: different locations and harvest times can result in different concentrations of active ingredients. Burkhard Bohne, master gardener and technical director of the Medicinal Plant Garden, therefore recommends finding a suitable location for the plant when cultivating sage in your own garden or balcony: “Common sage requires permeable, calcareous soil in a sunny, warm location. It is planted at intervals of 30 to 40 centimetres and can remain in position for several years. The sage is harvested shortly before flowering. Young leaves are used fresh or dried.” In the Medicinal Plant Garden, pharmacy students, but also interested visitors, are given an overview of native and foreign medicinal, aromatic and poisonous plants that can be cultivated here. The plants are divided into active ingredients and grow on an area of about 2,000 square metres. “The Medicinal Plant Garden fits in very well with our university’s research focus on Infection and Therapeutics. Here, students learn about active plant ingredients in practical applications. At the same time, we are able to communicate the topic of active ingredients to interested laypeople in a clear and vivid way,” says Rainer Lindigkeit. And Burkhard Bohne adds: “What makes the garden so popular with our visitors is the mixture of information on active ingredients and the tips we provide on cultivation and care”.


Picture of the month July 2020

The founding date of the Collegium Carolinum is clearly visible on the facade of the Altgebäude. Picture credits: Kristina Rottig/TU Braunschweig

1745: The founding date of the Collegium Carolinum is clearly visible on the facade of the Altgebäude. The roots for today’s Technische Universität Braunschweig were thus already laid 275 years ago. Even if we cannot celebrate this anniversary as planned, a special event is planned for the founding day to make the campus shine. But first of all we will look back on this founding period with our picture of the month. We will celebrate the founding day of the Collegium Carolinum and thus also of the TU Braunschweig on 5 July. On this day, 275 years ago, the first lectures took place at Bohlweg near the Hagenmarkt. And that in German language. This was not at all common: At the time, Latin was the language of instruction at universities – both nationally and internationally. Lectures at the Collegium began with subjects such as religion, Latin, Greek, geometry, arithmetic and physics. The first students had already enrolled on 29 June 1745: August Wilhelm Hassel from Wolfenbüttel and Justus Ludovicus Danielis Lambrecht from Jerxheim. Whether they took part in inauguration ceremonies together with their professors is unknown and, not least for financial reasons, rather unlikely. It is certain, however, that on July 5th only two professors were available for the time being: the classical philologist Elias Caspar Reichard (1714-1791) and Magister Johann Ludwig Oeder (1722-1776). He represented the teaching areas of physics and mathematics. In order to conserve the budget, people in the ducal service were given teaching positions. In the following years the teaching staff grew: full and associate professors, lecturers and lectors were added. In terms of educational history, the Collegium Carolinum belongs to the “high schools”, which were founded in many small principalities at that time and served the education of the nobility, but also of the middle classes. They represented a mixture of grammar school and university. The local initiator was the sovereign Duke Karl I of Braunschweig-Wolfenbüttel, as is also noted on the facade of the Altgebäude. As an enlightened prince he initiated numerous reforms. These included the Collegium Carolinum: it was intended to convey an understanding of science and the world based on “reason and utility”. The concept for this was presented by the ducal advisors Heinrich Bernhard Schrader von Schliestedt, later Minister of State, and the court preacher and prince-educator Johann Friedrich Wilhelm Jerusalem with the “Vorläufige Nachricht von dem Collegio Carolino”. In addition to mechanics, law, architecture, arts, languages, theology and foreign languages, it also took into account “Weltweisheit” (“world wisdom”). The target group of the Collegium Carolinum were young men from wealthy noble or middle-class families. Talented but fundless young men such as the well-known mathematician Carl Friedrich Gauss received scholarships. To celebrate the founding day of the Carolo-Wilhelmina on July 5, the TU Braunschweig will make the sky shine. The roof of the Haus der Wissenschaft will be illuminated in the anniversary colours in several scenes on 4 July from 11 pm. The dome light show will be on display throughout the entire “founding week” and will be the prelude to another project to mark the anniversary: a video by Braunschweig video and projection artist Christo Czichy will show projections on university buildings, combining the buildings and the research focus of the TU Braunschweig into his oeuvre.

Picture of the month June 2020

View into the model wave channel miniGWK+ of the Forschungszentrum Küste. Picture credits: Heiko Jacobs/TU Braunschweig

It is the little brother of the Large Wave Flume in its future expansion stage and yet it is quite large itself: the miniGWK+ of the Forschungszentrum Küste (FZK) of Technische Universität Braunschweig and Leibniz Universität Hannover, which we take a look at in our picture of the month, is about 30 metres long. In our picture of the month, however, only a small part of the model wave channel that was opened last year in Hannover-Marienwerder is shown. Here, the machine generated wave meets an angled plane in the rear part of the channel, which helps to dampen the wave. This prevents the water from simply splashing out of the channel. The 1:10 true scale model of the later GWK+ has a wave machine, a current system and a deep section. Here the scientists can systematically investigate how waves and currents influence each other. Both natural sea states and tidal currents in the North Sea can be mapped. This offers great potential for studies on offshore wind energy. Thus, the miniGWK+ will carry out initial studies on the ecosystem strengthening coastal protection of the research association “Gute Küste Niedersachsen” as well as on the effects of waves and storm surges on offshore wind industry facilities – all on a smaller scale, of course. Tsunami-like waves can also be generated in the model wave channel. The miniGWK+ will help to optimize the expansion of the Great Wave Flume in its planning phase. The knowledge gained from the model wave channel is also important for the optimal generation and analysis of waves in the future GWK+ – a worldwide unique large-scale research device with which the FZK can meet the energy transition topics offshore wind energy, tidal current energy and wave energy.

Picture of the month May 2020

Augmented and virtual reality goggles from the Institute for Didactics of the Natural Sciences are used in the physics teacher training. Picture credits: Markus Hörster/TU Braunschweig

Digital lectures, screencasts, collaborative working on the virtual whiteboard, student feedback via chat ­– the summer semester at TU Braunschweig is different. Teachers and students use new digital tools to make courses possible despite the distance. Augmented and virtual reality goggles – as seen in our picture of the month May – have already been experimented with for some time in physics teacher training. Junior Professor Oliver Bodensiek from the Department of Physics and Physics Didactics uses the goggles to make the invisible visible – for example electromagnetic fields. Augmented Reality thus achieves what the English term already suggests: the actual reality is expanded by additional content such as images, information, videos or even games. The “HoloLens 2” on the right of the picture can place holograms in physical-real space. It is controlled by intuitive gestures and speech, but gaze control is also possible in some cases by means of built-in eye-tracking. Augmented Reality goggles not only provide virtual insights into the inside of objects in teaching. They also enable visually guided learning, for example on experiments, machines or in surgery. In science lessons, for example, teachers can use the goggles to supplement experiments with visualizations of model predictions. The model parameters are linked to the measured data in real time. In this way, the real system behaviour and the behaviour of the associated model can be compared directly. “When optimally designed, this can, compared to other learning media, significantly reduce the cognitive load when solving associated problems and also increase the learning effectiveness. However, as far as the sensible and effective use of AR/VR in school lessons is concerned, we are still at the very beginning,” said Professor Bodensiek. Even this is feasible: the transformation through a completely virtual space – created by human hands. This requires another learning gadget: virtual reality glasses (Vive Pro Eye, left in the photo). The field of view is at about 110° diagonally much larger than in AR applications; it is operated via a controller. The real world plays no role in VR. Learners can “immerse” themselves in a situation, for example visit virtual laboratories or act as a teacher in a virtual classroom where student behavior is simulated. Without really hurting themselves, dangerous or complex processes – such as working on machines or high-voltage equipment – can also be trained. A high degree of immersion and presence can be achieved, i.e. users can experience the virtual world as almost real. In order to find out how teaching and learning environments in Augmented and Virtual Reality can be designed in a meaningful and learning-effective way, researchers at TU Braunschweig are investigating the factors that affect cognition and learning at these human-computer interfaces.

Picture of the month April 2020

Living cell factory under a special light microscope from the Institutes of Solid Mechanics and Biochemical Engineering. Picture credits: Markus Böl/TU Braunschweig

At first glance it could be the graphics of a thermal imaging camera. But in fact our picture of the month April shows a living cell factory under the microscope.The image was created in the course of a research cooperation between the Institute of Solid Mechanics and the Institute of Biochemical Engineering at the Technische Universität Braunschweig. Filamentous microorganisms such as fungi or bacteria of the genus Actinomycetes are used and cultivated in biotechnology as living cell factories, for example to produce valuable enzymes, organic acids or pharmaceutical agents. Depending on the conditions under which these microorganisms are cultivated, they develop different forms (morphologies). Their filamentous cells (hyphae) can grow as mycelia, in which each hyphe is surrounded by the culture medium, or they can form dense, pellet-like structures in which the hyphal agglomerates combine to form a mostly spherical pellet. The picture of the month shows the structure of such a pellet. Using a confocal microscope, a special light microscope, the scientists from the Institutes of Solid Mechanics and Biochemical Engineering of the TU Braunschweig have created a picture of a living cell factory. They have visualised the hyphal structure of a biopellet of the Actinomycetes bacterium Actinomadura namibiensis. The colour coding provides information on the position of the hyphae: blue hyphae are located close to the microscope objective, red ones are further away. A characteristic of filamentous microorganisms is that the viability and productivity of their hyphae are closely linked to the morphology of the pellet and especially to the density of the hyphae. Their morphology is significantly influenced by changes in cultivation conditions, such as the addition of salt. This is shown, for example, by the fact that the addition of salt also significantly changes the pellet stiffness. The researchers from the Institutes of Solid Mechanics and Biochemical Engineering carried out compression experiments using a micromanipulator. This is a measuring device with which forces and paths in the micronewton or micrometer range can be recorded on individual biopellets. Biopellets were clamped between two plates and the force response exerted by the hyphal structure was determined over the distance between the plates. The results of these investigations were recently published in the Biochemical Engineering Journal. As part of its metabolism, the bacterium A. namibiensis produces the antiviral agents Labyrinthopeptin A1 and A2. Labyrinthopeptin A1 shows antiviral activity against the Human Immunodeficiency Virus (HIV) and the Herpes Simplex Virus (HSV). In addition, synergistic effects with other standard antiretroviral drugs were found, which makes Labyrinthopeptin A1 a promising candidate for the development of a new broad-spectrum antibiotic. In contrast, Labyrinthopeptin A2 shows activity against neuropathic pain.

Picture of the month March 2020

Visualization of settlement patterns of the urban region of Qingdao from the Institute for Sustainable Urbanism. Picture credits: ISU/TU Braunschweig

How do we get an indepth understanding of urbanisation patterns in a rapidly growing urban region? And how do we open up new approaches for a more sustainable development? In the international inter- and transdisciplinary research project “EAST-CITIES”, the Institute for Sustainable Urbanism (ISU) of the Technische Universität Braunschweig is evolving the TOPOI method, which is applied to enable the integrated analysis and description of settlement patterns along an urban-rural gradient in Qingdao in the eastern Chinese province of Shandong in our picture of the month. The interdisciplinary EAST-CITIES team of Tongji University Shanghai, Technische Universität Braunschweig, GESIS Leibniz Institute for Social Sciences and partner institutions in Qingdao develop new approaches for integrated, data driven, scientifically validated, inter- and transdisciplinary founded sustainable development scenarios decoupling human development from negative environmental, social and economic impact. Researchers from the disciplines of architecture and urban planning, landscape and transport planning, engineering, economics and information sciences from China and Germany focus on the holistic development of “medium-sized” urban regions of up to 10 million inhabitants. The team of the Institute for Sustainable Urbanism (ISU) identifies and typifies existing and planned settlement patterns in Qingdao, China, on the basis of various attributes (e.g. density, functions, land use, accessibility, permeability, blue and green networks, proximity). In an iterative process, these TOPOI are enriched with findings of other disciplinary research, ultimately modeling and simulating the diverse interdependencies. Through the TOPOI method the scientists are able to gain a better understanding of settlement patterns along the urban-rural gradient. By evaluating these through a morphological approach it is possible to more accurately define and analyze dynamic urban-rural systems. The visualization gives insight into current EAST-CITIES research. ISU develops data-driven methods such as Image Classification to generate a comprehensive geospatial database based on satellite imagery and other accessible data sources. Based on this the scientists refine the TOPOI method initially developed within the METAPOLIS project. Model and data-driven multi-criteria geospatial analysis, advanced visualization techniques and visual analytic methods are applied to research on manifold attributes defining the Qingdao TOPOI, of which the map visualizes one: the proximity of buildings within a radius of 450 meters (5 minute walking distance) around each single building in the city. The ISU-team developed the map applying the Inverse Distance Weighted interpolation. IDW weighs the influence of one point to another relative to the distance between the points. This method allows to visualize building proximity and is one of a series of attributes describing the TOPOI to have a better understanding of the morphology and specifics of settlement patterns of Qingdao. Areas in purple have a low proximity score and areas in yellow have a high proximity score.

Picture of the month February 2020

Shapes made of ice and snow were created by architecture students from the Institute for Architecture-Related Art in Norway. Picture credits: Aleigh Smith

Will or won’t it come this winter? The snow. Things are looking bad for our region right now. Reason enough to choose a photo from a snow-sure area as the picture of the month February. In Vinje, a municipality in southern Norway, the scenery is covered with freshly fallen snow crystals in February. Perfect weather for skiing, sledding, snowball fights – and sculpting. This is why every year many people make a pilgrimage to Telemark for the “Vinje Snoforming Festival”. Students at the Institute of Architecture-Related Art at the TU Braunschweig have been shaping snow sculptures in this international and interdisciplinary exchange project for eight years in a row under the guidance of the artist Ilka Raupach. “A walk through the wilderness” is the name of the snow sculpture by Nils Aschemann, Isabel Dohle, Leo Goldenbaum, Nadine Grabiger, Johanna Hamel, Daniel Ilunga Matthiesen, Anna-Lisa Lignow, Jan Schellhorn, Aleigh Smith and Xingyu Zhu. Arranged around two concentric circles, each carefully crafted piece represents a state of wilderness: fear, refuge, expanse, liberation and tranquility. In Braunschweig, the architecture students designed their models on a scale of 1:30. On site, in Vinje, they decided where to place the sculptures – in keeping with their surroundings and facing the sun. Before the sculptural work could begin, the students had to construct three-metre high cubes using plywood boarding, which they filled with snow. The Braunschweig students moved 20 tons per cube – regardless of the weather conditions. They stamped the snow in the mould until it solidified. Then they could remove the wooden casing and let the raw blocks freeze overnight. Only then did the actual sculpting begin: first with shovels, then with saws and grinding tools to refine the shape. For one week they worked on their sculptures. Works that disappear when the snow melts. “This way, the snowy landscape becomes a laboratory for us. Walk-in sculptures and temporary architecture in the context of the landscape are created,” says Ilka Raupach. “Working with snow as a material offered the students a rare opportunity, as it is not a material typically used in architectural design. This unique experience will certainly influence their work as architects”.

Picture of the month January 2020

Quadrocopter ALiCE from the Institute of Flight Guidance will soon be in use on the MOSAiC expedition. Picture credits: Axel Behrendt

It is still properly packed in crates, underway on a ship from Bremerhaven, heading for the Arctic. Its destination is the icebreaker “Polarstern”, which is frozen in sea ice and drifting across the North Pole. The quadrocopter ALiCE of the Institute of Flight Guidance (IFF) at Technische Universität Braunschweig will be deployed on the MOSAiC expedition led by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). Our picture of the month shows it during the Polarstern expedition 2017 east of Greenland. Over the course of the five-week research expedition in September and October 2017, scientists Dr Falk Pätzold and Thomas Krüger from IFF, with support from ALiCE (Airborne tool for methane isotopic composition and polar meteorological experiments), investigated climate issues: how the atmosphere is affected by sea ice and what role sea ice plays in the introduction of methane into the atmosphere. Once again – for MOSAiC, the largest Arctic expedition in history – the quadrocopter will take air samples during flights “on sight” at altitudes of up to 1,000 metres. This will enable the research team to use isotope analysis to determine the sources of methane in the Arctic. Pätzold, a specialist for meteorological measurement technology at the IFF, will fly to Tromsø in Norway at the end of January and from there set out for the icebreaker “Polarstern” to join the international research team on the Arctic expedition. Besides ALiCE, the helicopter towed probe “HELiPOD” of IFF is also on its way to “Polarstern” – equipped with 60 measuring instruments, some new, some tried and trusted. In addition to atmospheric measurements, the ice surface is documented, aerosols are measured and the influence of clouds is analysed. The data will allow scientists to investigate interactions between sea ice, atmosphere and ocean. Pätzold will also be on board the helicopter and make sure that the HELiPOD sensors operate smoothly. According to AWI, hardly any other region has warmed up as significantly as the Arctic in recent decades. At the same time, however, year-round observations from the ice-covered Arctic Ocean are lacking. With the MOSAiC expedition this is now possible. The “Polarstern” and its international research team are spending a whole year in the Arctic, with the icebreaker drifting through the Arctic Ocean while it is frozen. This means that for the first time research can take place near the North Pole during the Arctic winter.

Picture of the month December 2019

It’s very Christmassy at the Institute for Electrical Measurement Science and Fundamental Electrical Engineering: Students made something different nutcrackers with 3D printing. Picture credits: Kristina Rottig/TU Braunschweig

Called back into action: nut tongs, screw nutcrackers, “Nusschleuders” and also nut biters – grim-looking wooden figures that crack walnuts, hazelnuts and almonds with their mouths using leverage. Somewhat different nutcrackers were created in the summer semester 2019 at the Institute for Electrical Measurement Science and Fundamental Electrical Engineering (EMG), which we show in our picture of the month. Students designed and produced a total of eight different models in their semester project for the lecture “Additive Manufacturing (3D Printing)”. They were free to let their creativity run wild. The only requirement was that all printing processes available at the institute had to be used and that the object should be able to really crack peanuts, walnuts or hazelnuts at the end of the final presentation. “That actually worked for most of them, although some designs had to surrender  hazelnuts, at the latest, and occasionally broke,” says Dr. Benedikt Hampel, who gives the lecture and has already dealt with the topic of 3D printing in his doctorate. In the course, the students first learned the basics of construction on the computer, so that they could later use it to design objects for 3D printing. Subsequently, the details of different printing processes with their advantages and disadvantages were discussed. Of course, the practice in 3D printing was not to be missed. Some groups focused on attractive design: for example, a dinosaur and a nut-cracking helicopter were created. Other students implemented additional functions in their objects so that different adapters were developed for the different nuts or collection containers for collecting the nutshells. In one project, electronics were even implemented to display the nutcracking force using both LEDs and a computer. There will be a new task during the lecture next summer semester. It will be interesting to see which creative ideas the students will implement.

Picture of the month November 2019

Graphite anode in the drying channel of the continuous coating line at Battery LabFactory Braunschweig (BLB). Picture credits: Marisol Glasserman/TU Braunschweig

It has become an integral part of many areas of our lives and is used primarily as a mobile energy storage device in smartphones, notebooks and electric cars: the lithium-ion battery is currently in the focus of science in order to economically and eco-efficiently implement topics such as the energy revolution and the change in propulsion technologies. Our picture of the month was taken in the drying channel of the continuous coating line at Battery LabFactory Braunschweig (BLB). These are the process steps “coating and drying”, two of 18 process steps in total that a lithium-ion battery passes through during production. In the simplest case, a lithium-ion battery cell consists of two electrodes (anode and cathode), an electrolyte and the separator, which electrically separates the two electrodes from each other. The picture of the month shows a copper foil on which the active electrochemical and passive materials were applied in advance using a comma bar process, i.e. a coating process. This is a graphite anode that represents the negative electrode. Of the various institutes that are active at BLB, the Institute for Particle Technology deals, among other things, with the process steps of coating and drying.  An alternative process that is being investigated at BLB is slot die coating. Besides the advantage of the intermittent coating, a coating with interruptions, the independence of the coating thickness from the properties of the electrode paste is given here. Drying is a cost-intensive step in all industrial processes. The main focus is on technologies such as infrared drying to increase drying speeds and reduce energy costs. Furthermore, coating errors and binder migration can be avoided through optimized drying, thus reducing material waste.

Picture of the month October 2019

What does an AI see in a photo of the BRICS building? Picture credits: Erwin Quiring und Prof. Konrad Rieck/TU Braunschweig

Klimt, Hundertwasser or who created this psychedelic picture? As a matter of fact, the photo, in which BRICS building can be made out in the background, comes from the Institute for System Safety at the TU Braunschweig. It gives an exciting insight into the world of artificial intelligence. In the photo, the scientists have reinforced the patterns that an artificial neural network “sees” internally. To classify the image as a building, dog or street sign, for example, the network first extracts fine block structures that were reinforced throughout the photo. Later, these are processed internally into more complex patterns, easily recognizable by the dog’s snouts. This example visually shows how we can better understand artificial neural networks before they are implemented, for instance in autonomous driving vehicles. As part of their research at the Institute for System Security, the scientists are investigating the use of artificial intelligence in safety-critical applications. They research how intelligent systems can be trained on the basis of data and thus adapt themselves to new risks. In this way, researchers can, for example, develop new methods for detecting computer malware. However, today’s artificial intelligence methods are themselves vulnerable. Attackers can either manipulate the learning process itself or produce the desired output through targeted manipulation. It has been shown, for example, that by affixing stickers to road signs it is possible to specifically manipulate the recognition of autonomous vehicles. Because of this, the institute scientists are also also investigating the target of artificial
intelligence. A better understanding of the learned interrelationships themselves is a key issue here – similar to how an exam helps to understand what the students have learned from a lecture.

Picture of the month September 2019

View into the sample chamber of the X-ray photoelectron spectrometer (XPS) in the LENA, which is used for example in biomedical engineering. Picture credits: Markus Hörster/TU Braunschweig

Our picture of the month September comes from the new Research Center for Quantum and Nanometrology, “Laboratory for Emerging Nanometrology” (LENA). More precisely, it is a direct view into the sample chamber of one of the large nanoanalytical instruments, the X-ray photoelectron spectrometer (XPS). This is a surface-sensitive technique that allows qualitative and quantitative statements to be made about the chemical elements present on the surface as well as their chemical environment, bonds and oxidation state.

The XPS is used, for example, in biomedical engineering. Within the research group “FOR 2180 Graded Implants”, Sarah Oehmichen from the Institute of Technical Chemistry deals with the surface optimization of polymer-based implants. These are electro-spun fibre mats which have been modified both in a classical chemical way and by plasma treatment. The XPS methodology is used here to prove the success of the respective modification and to better understand and classify results from other investigations, for example from cell tests. This is done with regard to the development of an implant for the tendon-bone transition in the shoulder. Another field of application is battery research, where the analysis of material properties on surfaces and interfaces plays an important role.

Technical details

The new measurement setup in the LENA is equipped in such a way that scientists can reduce the standard information depth of this technique from 10 nm (with monochromatized Al K-alpha at 1486eV) to the outermost 1-3 nm of the sample surface by angle-resolved measurements or increase it to up to 15-20 nm by using a different anode material. With the help of an Arn+ Gas Cluster ion source, depth profiles can be recorded, which then make it possible to look even deeper into the sample. In addition to XPS, other measurement modes such as UPS, ISS, AES, SEM and SAM are also possible.