Arbeitspapiere der BAM
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- Bioconjugation (2)
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- Iterative shrinkage thresholding algorithm (2)
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- Photothermal super resolution (2)
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Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (8)
- 6 Materialchemie (6)
- 1.5 Proteinanalytik (5)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (5)
- 8 Zerstörungsfreie Prüfung (4)
- 8.0 Abteilungsleitung und andere (3)
- 1.4 Prozessanalytik (2)
- 1.7 Organische Spuren- und Lebensmittelanalytik (2)
- 5 Werkstofftechnik (2)
- 6.3 Strukturanalytik (2)
The SUSAN-project aimed at developing a sustainable and safe strategy for nutrient recovery from sewage sludges using thermal treatment. Mono-incineration of the sludges completely destructs the organic pollutants in a first step. The incineration residues are ashes with a high phosphorus content that still contain heavy metal compounds above the limits for agricultural use. Furthermore, phosphorus in the ashes exhibits low bioavailability - a disadvantage in farming. Therefore, in a second thermochemical step heavy metals are removed and phosphorus transferred into mineral phases available for plants. The principle of the SUSAN-project is the separation of the small heavy metals fraction from the ashes to receive a phosphorus rich product suited as raw material for fertilisers that also contains SiO2, CaO, Al2O3, Fe2O3, MgO and K2O.
The thermochemical process is based on evaporation of volatile heavy metal chlorides at 850 - 1000 °C. The sewage sludge ashes are mixed with chlorine donors such as MgCl2 or KCl, grained and treated in a thermal aggregate e.g. a rotary furnace. At the same time a transfer of non soluble P-compounds into Mineral phases available for plants takes place.
Besides technological development of the thermochemical process, the products fertilisation performance, the product design, the market for the products and the sustainability of the whole process chain are emphasised in the SUSAN-project.
Learned block iterative shrinkage thresholding algorithm for photothermal super resolution imaging
(2020)
Block-sparse regularization is already well-known in active thermal imaging and is used for multiple measurement based inverse problems. The main bottleneck of this method is the choice of regularization parameters which differs for each experiment. To avoid time-consuming manually selected regularization parameters, we propose a learned block-sparse optimization approach using an iterative algorithm unfolded into a deep neural network. More precisely, we show the benefits of using a learned block iterative shrinkage thresholding algorithm that is able to learn the choice of regularization parameters. In addition, this algorithm enables the determination of a suitable weight matrix to solve the underlying inverse problem. Therefore, in this paper we present the algorithm and compare it with state of the art block iterative shrinkage thresholding using synthetically generated test data and experimental test data from active thermography for defect reconstruction. Our results show that the use of the learned block-sparse optimization approach provides smaller normalized mean square errors for a small fixed number of iterations than without learning. Thus, this new approach allows to improve the convergence speed and only needs a few iterations to generate accurate defect reconstruction in photothermal super resolution imaging.
This paper presents deep unfolding neural networks to handle inverse problems in photothermal radiometry enabling super resolution (SR) imaging. Photothermal imaging is a well-known technique in active thermography for nondestructive inspection of defects in materials such as metals or composites. A grand challenge of active thermography is to overcome the spatial resolution limitation imposed by heat diffusion in order to accurately resolve each defect. The photothermal SR approach enables to extract high-frequency spatial components based on the deconvolution with the thermal point spread function. However, stable deconvolution can only be achieved by using the sparse structure of defect patterns, which often requires tedious, hand-crafted tuning of hyperparameters and results in computationally intensive algorithms. On this account, Photothermal-SR-Net is proposed in this paper, which performs deconvolution by deep unfolding considering the underlying physics. This enables to super resolve 2D thermal images for nondestructive testing with a substantially improved convergence rate. Since defects appear sparsely in materials, Photothermal-SR-Net applies trained blocksparsity thresholding to the acquired thermal images in each convolutional layer. The performance of the proposed approach is evaluated and discussed using various deep unfolding and thresholding approaches applied to 2D thermal images. Subsequently, studies are conducted on how to increase the reconstruction quality and the computational performance of Photothermal-SR-Net is evaluated.
Thereby, it was found that the computing time for creating high-resolution images could be significantly reduced without decreasing the reconstruction quality by using pixel binning as a preprocessing step.
Laser excited super resolution thermal imaging for nondestructive inspection of internal defects
(2020)
A photothermal super resolution technique is proposed for an improved inspection of internal defects. To evaluate the potential of the laser-based thermographic technique, an additively manufactured stainless steel specimen with closely spaced internal cavities is used. Four different experimental configurations in transmission, reflection, stepwise and continuous scanning are investigated. The applied image post-processing method is based on compressed sensing and makes use of the block sparsity from multiple measurement events. This concerted approach of experimental measurement strategy and numerical optimization enables the resolution of internal defects and outperforms conventional thermographic inspection techniques.
Efforts are rising in opening up science by making data more transparent and more easily available, including the data reduction and evaluation procedures and code. A strong foundation for this is the F.A.I.R. principle, building on Findability, Accessibility, Interoperability, and Reuse of digital assets, complemented by the letter T for trustworthyness of the data. Here, we have used data, which was made available by the Institute Laue-Langevin and can be identified using a DOI, to follow the F.A.I.R.+T. principle in extracting, evaluating and publishing triple axis data, recorded at IN3.
With Direct Laser Writing (DLW) maturing in all aspects as a manufacturing technology a toolset for quality assurance must be developed. In this work we want to introduce a first of its kind test artifact. Test artifacts are standardized 3D models with specific geometric feature to evaluate the performance of writing parameters. Test artifacts are already common in other 3D additive manufacturing technologies e.g. Selective Laser Melting. The test artifact introduced in this work was developed in particular to accommodate 1) the high geometrical resolution of DLW structures and 2) the limited possibilities to examine the resulting structure. Geometric accuracy, surface adhesion as well as confocal raman spectroscopy results were considered when evaluating the design of the test artifact. We will explain the individual features and design considerations of our DLW test artifact. The difference between two slicers, Cura and 3DPoli, and the implications on measured feature sizes and the general shape is quantified. The measured geometries are used to derive a general design guide for a specific combination of photoresist, laser power and scanning speed and to analyse the geometric accuracy of a structure produced using these guidelines.
The processes of hydrogen reduction of silicon and germanium chlorides under the conditions of radio-frequency (40.68 MHz) counteracted arc discharge stabilized between two rod electrodes were investigated. The main gas-phase and solid products of plasma-chemical transformations were determined.
Thermodynamic analysis of SiCl4 + H2 and GeCl4 + H2 systems was carried out. It is shown that under the implemented experimental conditions, equilibrium components of the products are established. The detected spectra of chemical activity were studied, which gave reason to assume that the molecular mechanism of the hydrogen reduction process is the main one. The impurity composition of gas-phase and solid reaction products was investigated. The possibility of single-stage production of high-purity Si and Ge mainly in the form of compact ingots, as well as high-purity chlorosilanes and trichlorogermane, was shown.
Determining a pore structure’s mechanical and chemical data on lime rendering exposed
outdoors and including masonry in the laboratory, with regard to their behaviour on moisture
transport and weathering was the objective. In search of clues for a dose-response relation -
i.e. upon a connection between the emission rate of SO2 and NOx on one hand and the degree
of damage to mainly plaster having a lime component on the other - it has been of interest to
what extent their structural characteristics including pore space are modified and so
consequently also physico-technical properties and chemical composition. For determining
corresponding criteria, a widely diversified spectrum of test methods such as to obtain data
concerning porosity and moisture transport, mechanical behaviour, and chemistry as well is
available. A description of the manufacture of plate-shaped rendering specimens with lime
putty, industrially hydrated lime and dolomitic hydrate (the last two also having a cement
admixture) and also hydraulic lime as binding agents is included. First deposition velocity and
absorption rate for SO2 were determined in laboratory tests on these materials in dry and
moist states. After their exposure on outdoor racks at six locations in the Berlin region with
differing SO2 atmospheric contents over at least 5 years, the samples of course show timedependent
modifications of chemical and physical qualities which are especially reflected in
the form of profiles of structure, strength and concentration, e.g. for sulphate. Local climatic
differences, however, partly exert a greater influence on material than emissions. Similar
investigations were performed on samples of comparable composition exposed 4 and 17
years. But the real surprise is furnished by the renderings’ behaviour depending upon
orientation and upon height at a building. Since weathering behaviour and moisture transport
(absorption, storage, release) are directly interdependent, further criteria are necessary for a
critical assessment of a plasters’ pore structure. Starting from sands, plasters were
characterized. The structural parameters were lastly influenced by the respective contents of
sand, binder and mixing water. These results and those gained from bricks naturally find their
expression in masonry sections manufactured there from, and above all in their capillary and
evaporative behaviours, and also when applying different test liquids. Summary and cited
literature is given at the end of this report.
H2Sense - Cost-effective and reliable Hydrogen Sensors for Facilitating the Safe Use of Hydrogen
(2016)
The H2SENSE (Cost-effective and reliable hydrogen sensors for facilitating the safe use of hydrogen) project promoted hydrogen primarily, but not exclusively, for its use as an alternative fuel. It brought together different stakeholders including sensor manufacturers, end-users, certification bodies and independent evaluators to ensure the optimum use of low-cost and reliable hydrogen sensors.
Project partners analysed sensor performance in real-life applications in industrial environments and identified increased requirements for sensors and for regulations, codes and standards. H2SENSE also facilitated the safe use and implementation of hydrogen as an alternative fuel by ensuring the correct use of effective hydrogen detection devices.
European scientists worked together with colleagues from the National Renewable Energy Laboratory (NREL) in Colorado, USA. They pooled their knowledge of developments in hydrogen sensor technology as well as deployment and commercialisation strategies. These benefits will be continued through trans-Atlantic inter-laboratory sensor testing programmes in which EU and US laboratories perform complementary tests and exchange results.
T cells need to adapt their cellular metabolism for effector cell differentiation. This relies on alterations in mitochondrial physiology. Which signals and molecules regulate those alterations remains unclear. We recently reported, that the mitochondrial protein TCAIM inhibits activation-induced changes in mitochondrial morphology and function and thus, CD effector T cell formation. Using conditional TCAIM knock-in (KI) and knockout (KO) mice, w now show that it also applies to CD8+ T cells and more importantly, delineate the molecular processes in mitochondria by which TCAIM controls effector cell differentiation. TCAIM KI resulted in reduced activation-induced HIF1α protein expression. Metabolomics and transcriptional data in combination with mathematical flux modeling revealed an impaired induction of anabolic pathways, especially of the mevalonate pathway and cholesterol biosynthesis in TCAIM KI CD8+ T cells. Addition of cholesterol completely rescued HIF1α protein expression, activation and proliferation of TCAIM KI CD8+ T cells. At the molecular level, TCAIM delayed activation-induced mitochondria-ER contact (MERC) formation by binding to MERC promoting proteins such as RMD3 and VDAC2. In summary, we demonstrate that TCAIM suppresses effector cell differentiation by inhibiting MERC formation, which induce HIF1α-mediated increase in cellular metabolism and cholesterol biosynthesis.
Particle size determination of a commercially available CeO2 nano powder - SOPs and reference data
(2023)
Compilation of detailed SOPs for characterization of a commercially available CeO2 nano powder including
- suspension preparation (indirect and direct sonication),
- particle size determination (Dynamic Light Scattering DLS and Centrifugal Liquid Sedimentation CLS) with reference data, respectively.
For sample preparation and analysis by Scanning Electron Microscopy (SEM) of this powder see related works (submitted, coming soon).
Globally, cement and concrete experts are at the cutting-edge to sustainable, green, healthy but nonetheless high-performance concrete. Today concrete is not yet well established in Africa, which offers the unique opportunity to build up a cement and concrete market based on the highest available state of technology. As this industry needs high level expertise, a central issue in implementation of skilled technology is crosslinking research institutions and laboratories. It should not be neglected that concrete is a product with low transport ranges. This means that an improved concrete market mainly supports the local economy without exceeding financial drains to the international market. Thus it fosters the fight against poverty, which is an urgent need in most African countries. The project aims to cross-link experts with industry and policy making bodies, aiming to establish sustainable cement and concrete construction in Africa.
In the last years, the Process Analytical Technology (PAT) research field has become of great importance due to its connection with the industrial world. This industry related research, along with the evolutionary progress that technology has seen lately, has allowed that key analytical techniques in an industrial environment have undergone a radical development. One of these techniques has been the near-infrared spectroscopy (NIRS). This technique, currently common in "online" industrial analysis, has seen a remarkable revolution, especially since the introduction of the microelectromechanical systems technology (MEMS) in the spectroscopy field. Nowadays it is possible to find compact spectrometers no bigger than a wristwatch in the market. Although there is an unavoidable question: can these compact spectrometers actually compete against the traditional spectrometers?
In this project different calibration parameters of two compact NIR spectrometers ("Spectral Engines Oy NIR-One Sensor NM2.0", with 1550 to 1950 nm range; and "NeoSpectra Si-ware", with 1300 to 2550 nm range) were evaluated, and the obtained results were compared with a reference spectrometer ("Bruker Optik GmbH Matrix-F", with 15000 to 4000 cm–1 range). In order to obtain the different calibration parameters, a sequence of quality performance tests were conducted. The results obtained after the different experiments carried out with both compact spectrometers prove that their performance is more than acceptable for routine analysis.
Afterward, model samples of different microplastics in soil at different known concentration were analyzed with all three spectrometers. Chemometric models capable to identify and classify microplastics in soil were established. For this analysis five of the most used plastics worldwide were used: polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). After the Principal component analysis (PCA), it can be seen that only the NIR-One NM2.0 is capable to differentiate all types of microplastics in soil at concentrations of 1–2 %, while the NeoSpectra Si-ware is unable to identify the PET sample.
CHEF provides knowledge about flood protection of cultural heritage objects and directly supports the European Floods Directive by giving recommendations on how to assess the vulnerability of monuments. A comprehensive analysis of protective measures BEFORE, DURING and AFTER a flood has been carried out within the project, including technical and administrational measures. An overview of these measures is given, followed by recommendations on how to establish the most effective protective strategies.
In a color X-ray camera spatial resolution is achieved by means of a polycapillary optic conducting X-ray photons from small regions on a sample to distinct energy dispersive pixels on a CCD matrix. At present, the resolution limit of color X-ray camera systems can go down to several microns and is mainly restricted by Pixel dimensions. The recent development of an efficient subpixel resolution algorithm allows a release from pixel size, limiting the resolution only to the quality of theoptics. In this work polycapillary properties that influence the spatial resolution are systematized and assessed both theoretically and experimentally. It is demonstrated that with the current technological Level reaching one micron resolution is challenging, but possible.
We demonstrate a strategy for simulating wide-range X-ray scattering patterns, which spans the small- and wide scattering angles as well as the scattering angles typically used for Pair Distribution Function (PDF) analysis. Such simulated patterns can be used to test holistic analysis models, and, since the diffraction intensity is on the same scale as the scattering intensity, may offer a novel pathway for determining the degree of crystallinity.
The "Ultima Ratio" strategy is demonstrated on a 64-nm Metal Organic Framework (MOF) particle, calculated from Q < 0.01 1/nm up to Q < 150 1/nm, with a resolution of 0.16 Angstrom. The computations exploit a modified 3D Fast Fourier Transform (3D-FFT), whose modifications enable the transformations of matrices at least up to 8000^3 voxels in size. Multiple of these modified 3D-FFTs are combined to improve the low-Q behaviour. The resulting curve is compared to a wide-range scattering pattern measured on a polydisperse MOF powder. While computationally intensive, the approach is expected to be useful for simulating scattering from a wide range of realistic, complex structures, from (poly-)crystalline particles to hierarchical, multicomponent structures such as viruses and catalysts.
A Round Robin study has been carried out to estimate the impact of the human element in small-angle scattering data analysis. Four corrected datasets were provided to participants ready for analysis. All datasets were measured on samples containing spherical scatterers, with two datasets in dilute dispersions, and two from powders.
Most of the 46 participants correctly identified the number of populations in the dilute dispersions, with half of the population mean entries within 1.5 % and half of the population width entries within 40 %, respectively. Due to the added complexity of the structure factor, much fewer people submitted answers on the powder datasets.
For those that did, half of the entries for the means and widths were within 44 % and 86 % respectively. This Round Robin experiment highlights several causes for the discrepancies, for which solutions are proposed.
Ultra-SAXS can enhance the capabilities of existing SAXS/WAXS beamlines and laboratory instruments. A compact Ultra-SAXS module has been developed, which extends the measurable q-range with 0:0015 < q 1/nm) < 0:2, allowing structural dimensions between 30 < D(nm) < 4000 to be probed in addition to the range covered by a high-end SAXS/WAXS instrument. By shifting the module components in and out on their respective motor stages, SAXS/WAXS measurements can be easily and rapidly interleaved with USAXS measurements.
The European Water Framework Directive (WFD) 2000/60/EC specifies a list of 33 priority water pollutants. For these substances, Environmental Quality Standards (EQS), equivalent to the maximum allowable concentrations, had been defined at very low levels.
EQS values refer to the whole water body, i.e. include contaminants which are associated to suspended solids or colloids present in the natural water. For several priority pollutants primary analytical methods capable of measuring the target analytes at EQS level in natural water are still missing. The project has developed and validated such methods for three selected compounds, namely Tributyltin (TBT), Polybrominated Diphenylether (PBDE) and Polycyclic Aromatic Hydrocarbons (PAH).
Recently, we suggested an unconventional approach [the so-called Internal-Field-Guarded-Active-Region Design (IFGARD)] for the elimination of the crystal polarization field induced quantum confined Stark effect (QCSE) in polar semiconductor heterostructures. And in this work, we demonstrate by means of micro-photoluminescence techniques the successful tuning as well as the elimination of the QCSE in strongly polar [000-1] wurtzite GaN/AlN nanodiscs while reducing the exciton life times by more than two orders of magnitude. The IFGARD based elimination of the QCSE is independent of any specific crystal growth procedures. Furthermore, the cone-shaped geometry of the utilized nanowires (which embeds the investigated IFGARD nanodiscs) facilitates the experimental differentiation between quantum confinement- and QCSE-induced emission energy shifts. Due to the IFGARD, both effects become independently adaptable.