Picture of the month
Picture of the Month: Etched Topographic Map in Gallium Nitride
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.
Pixel by pixel towards the topographic map
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.
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Pictures of previous months
Picture of the month September 2020
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
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
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
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
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
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
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
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
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
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
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
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
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.
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.