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## Summary:
This notebook and associated datasets (including VASP details) accompany a manuscript available on the ArXiv (https://doi.org/10.48550/arXiv.2303.13435) and hopefully soon in a journal as short communication as well. Most of the details needed to understand this notebook are explained in that paper with the same title as above. For convenience, the abstract is repeated here:
## Paper abstract:
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 presented coupled to 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 $Q<0.01$\,$\mathrm{nm}^{-1}$ up to $Q\approx150$\,$\mathrm{nm}^{-1}$, with a resolution of 0.16\,\AA. 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.
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.
Simulates X-ray and Neutron scattering patterns from arbitrary shapes defined by STL files.
Features:
- Uses multithreading to compute a number of independent solutions, then uses the variance of the results to estimate an uncertainty on the output.
- Can be launched from the command line using an excel sheet to define settings, or from a jupyter notebook.
- Outputs scattering patterns in absolute units if the contrast is set.
- A Gaussian size distribution is available, where the relative scaling of objects for each repetion can be varied. Recommended to be used with limited width (max. 10%) to avoid artefacts.
- Writes results with settings to an archival HDF5 file.
Application examples:
This software has been used in several studies to date. For example, it has been used here to simulate a model scattering pattern for a cuboid shape, which was then fed forward into the McSAS3 analysis program for analyzing scattering patterns of polydisperse cuboids. A second use is here, where it was used for the modeling of flattened helices. In this paper, scattering pattern features could be matched with particular morphological changes in the structure. Lastly, this paper has an example where it was used to validate the analytical analysis model, and explore the realistic limits of application of the analytical model.
These are four datasets that were made available to the participants of the Small-angle Scattering data analysis round robin. The intent was to find out how comparable results from different researchers are, who analyse exactly the same processed, corrected dataset.
In this repository, there are:
1) a PDF document with more details for the study,
2) the datasets for people to try and fit
3) an Excel spreadsheet to document the results.
Datasets 1 and 2 were modified from: Deumer, Jerome, & Gollwitzer, Christian. (2022). npSize_SAXS_data_PTB (Version 5) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.5886834
Datasets 3 and 4 were collected in-house on the MOUSE instrument.
In this work, we describe the synthesis, structural and photophysical characterization of four novel Pd(II) and Pt(II) complexes bearing tetradentate luminophoric ligands with high photoluminescence quantum yields (FL) and long excited state lifetimes (s) at room temperature, where the results were interpreted by means of DFT calculations. Incorporation of fluorine atoms into the tetradentate ligand favors aggregation and thereby, a shortened average distance between the metal centers, which provides accessibility to metal–metal-to-ligand charge-transfer (3MMLCT) excimers acting as red-shifted Energy traps if compared with the monomeric entities. This supramolecular approach provides an elegant way to enable room-temperature phosphorescence from Pd(II) complexes, which are otherwise quenched by a thermal population of dissociative states due to a lower ligand field splitting. Encapsulation of These complexes in 100 nm-sized aminated polystyrene nanoparticles enables concentration-controlled aggregation-enhanced dual emission. This phenomenon facilitates the tunability of the absorption and emission colors while providing a rigidified environment supporting an enhanced FL up to about 80% and extended s exceeding 100 ms. Additionally, these nanoarrays constitute rare examples for selfreferenced oxygen reporters, since the phosphorescence of the aggregates is insensitive to external influences, whereas the monomeric species drop in luminescence lifetime and intensity with increasing triplet molecular dioxygen concentrations (diffusion-controlled quenching).
Laminography is a widely used NDT technique for large flat object which cannot be investigated by traditional computed tomography. However, due to the limited scanning angle of laminography, the reconstructed image has more artifact interference, which seriously affects the reconstructed image quality. Reducing artifacts of the laminography image and enhancing the images have become important research effort. In this paper, we present dual-energy materials characterization methods based on photon counting detectors to reduce artifacts and enhance image for laminography. The photon counting detector used in this study allows the setting of two independent energy thresholds in order to acquire dual-energy images for laminography from a single scan. The dual energy imaging methods of basis material decomposition (BMD) and weighted logarithmic subtraction (WLS) were studied in the paper with respect to laminography image enhancement. A fast decomposition algorithm on laminographic projection domain with approximating the inverse dual-energy equations to calculate the thickness of basic materials was used in the BMD dual-energy imaging methods. The experimental results show that the BMD method can characterize materials and enhance features of the basic material within the laminographic dataset. In the WLS method, a linear operation was applied on dual-energy images reconstruction directly, which can eliminate the attenuation of one specific material in the resultant image by setting an appropriate weighting factor. In our experiments. WLS method was used successfully to eliminate the strong artifacts generated by the special material and enhance the images. Dual-energy materials characterization methods based on photon counting detectors show potential applications in laminography.
Water Migration in One-Side Heated Concrete: 4D In-Situ CT Monitoring of the Moisture-Clog-Effect
(2018)
In order to study damage in concrete exposed to fire, a series of continuous X-ray computed tomography (CT) measurements were performed on a concrete sample heated, in-situ, on one side. The water migration relative to time and 3D space and, in particular, the dynamic condensation and vaporization of water droplets in the pores was quantified. This approach shows significant potential for further investigation of fire-related concrete damage.
Ultrashort laser pulse micromachining features a high precision. By increasing the repetition rate of the applied laser to several 100 kHz, laser processing becomes quick and cost-effective and make
this method attractive for industrial applications. Upon exceeding a critical laser intensity, hard X-ray radiation is generated as a side effect. Even if the emitted X-ray dose per pulse is low, the accumulated X-ray dose becomes significant for high-repetition-rate laser systems so that radiation
safety must be considered.
Faser-Kunststoff Verbunde und insbesondere Kohlenstofffaserverstärkte Kunststoffe werden bereits im Bereich der hohen (HCF) und sehr hohen Lastspielzahlen (VHCF) eingesetzt. Während statische Festigkeiten für diese Materialien bereits gut vorhersagbar sind, gibt es noch keine verlässliche Methode Schwingfestigkeiten zu bestimmen.
Vergangene Studien an Faser-Kunststoff Verbunden an der BAM zeigten, dass bei Schwingbelastung Mikrorisse und Zwischenfaserrisse bereits weit vor dem finalen Versagen auftreten. Diese Schäden erhöhen die innere Oberfläche des Materials. Die Änderung der inneren Oberfläche kann mittels der Röntgenrefraktion bestimmt werden.
Damit konnte im Rahmen der aktuellen Arbeit eine Lastgrenze ermittelt werden, bei der im untersuchten Lastwechselbereich keine Mikrorisse auftreten. Unter den gegebenen Material- und Versuchsparametern kann damit von einer ermittelten Dauerfestigkeitsgrenze gesprochen werden.
Nondestructive investigation of the VHCF-endurance on cyclically loaded CFRP by X-Ray-Refractography
(2016)
Carbon fiber-reinforced-plastics (CFRP) are already used under high-cycle- (HCF) and very-high-cycle-fatigue (VHCF) at relatively low loads not only in aerospace industry, but also in other growing markets like especially wind energy and increasingly also automotive industry. While the static strength of CFRP is satisfyingly predictable by means of layerwise-strenght-analysis and material data from single layers, it is more and more uncertain to predict residual strength or lifetime as the design lifetime increases. Previous studies showed that local minor cracks and inter-fiber-fracture (IFF) originate long before total failure of single layers. Reliable fatigue estimation for fiber-reinforced-plastics is not available at present. Subsequently safety-related primary structures made out of FRP are over dimensioned.
It is possible to detect the change of inner surface in a specimen by means of X-Ray-Refractography. This includes voids, intact fiber-matrix-interfaces as well as defective ones, cracks and all interfaces in plane with the X-Ray-beam. As the crack-density (including IFF) increases, the inner surface of the material correspondingly increases.
The borderline where even at high cycles no early cracks were detected was identified for selected laminates out of woven and non-crimped fabric with epoxy-matrix.
When no micro-cracks were detected up to 106 cycles, the specimens also lasted in the VHCF-regime. Furthermore for the epoxy resin LY556 in combination with carbon fiber it was distinguished that at a load minor to 50% IFF-load level, no micro cracks were detected and consequently the VHCF-endurance reached.
The integration of the set-up small-sized testing machine into the X-Ray buildup in order to achieve in-situ non-destructive detection of the crack initiation while loading the specimens (CFRP and GFRP- woven fabric and non-crimped-fabric) at the same time will increase the performance of the studies.
In earlier investigations at BAM it was shown, that the matrix has a strong influence on the micro-crack formation and finally on the total lifetime. In order to determine the influence of the matrix properties on the boarderline to infinite life, research is done on laminates while replacing the epoxy-based matrix with an equivalent one with different fracture mechanical properties.
With the evolution of early cracks and IFF monitored as well as the influence of the matrix on the crack propagation investigated we are working on an appropriate model to improve lifetime prediction in CFRP. This work is done within the priority program “infinite life” (SPP 1466) funded by Deutsche Forschungsgemeinschaft (DFG).