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Paper des Monats
- ja (31)
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.
The ionic liquid 1,3-dimethyl-imidazolium-dimethylphosphate ([MMIM]+[DMP]−) was analyzed using (hard) x-ray photoelectron spectroscopy.
Here, XPS and HAXPES spectra are shown in comparison. For the acquisition of the XPS spectra, monochromatic Al Kα radiation at 1486.6 eV was used, while for the acquisition of the HAXPES spectra, monochromatic Cr Kα radiation at 5414.8 eV was applied. Here, survey scans and high-resolution spectra of P 2p, P 2s, C 1s, O 1s, and N 1s for both methods and P 1s, P KL2,3L2,3, and P KL1L2,3 for HAXPES are shown.
1-Propyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide (Solarpur®), an ionic liquid was purchased from Merck (formerly Sigma Aldrich), was analyzed using hard x-ray photoelectron spectroscopy (HAXPES). The liquid is UHV stable, vertically and laterally homogeneous, and is easy to clean; thus, it can be used as a reference material. The HAXPES spectra of Solarpur® obtained using monochromatic Cr Kα radiation at 5414.8 eV include a survey scan, high-resolution spectra of C 1s, O 1s, N 1s, S 2p, S 1s, S 2s, F 1s, and S KLL.
Das polnische Bergbauinstitut GIG richtet alle zwei Jahre eine Fachtagung mit dem Thema „Sicherheit bei Sprengarbeiten“ im kleinen Bergstädtchen Ustroń (Polen) aus. Die Tagung hat eine internationale Ausrichtung und bietet Vorträge und Themen sowohl in englischer als auch polnischer Sprache. Es werden Ergebnisse anwendungsorientierter Forschung sowie aus der Praxis der Sprengarbeit vorgestellt. Teilnehmer und Beiträge kommen sowohl von großen Bergbaubetrieben und in Polen tätigen Herstellern als auch von Instituten und Behörden. Im Jahr 2018 war auch die BAM vertreten und der Autor möchte hiermit von den vielfältigen Themen berichten. Es gibt eine gewisse Ähnlichkeit zu der jährlich in Siegen stattfindenden „Informationstagung Sprengtechnik“ des Deutschen Sprengverbandes, wobei bisher wenig inhaltlicher Austausch stattfindet.
Large-language models (LLMs) such as GPT-4 caught the interest of many scientists. Recent studies suggested that these models could be useful in chemistry and materials science. To explore these possibilities, we organized a hackathon. This article chronicles the projects built as part of this hackathon. Participants employed LLMs for various applications, including predicting properties of molecules and materials, designing novel interfaces for tools, extracting knowledge from unstructured data, and developing new educational applications. The diverse topics and the fact that working prototypes could be generated in less than two days highlight that LLMs will profoundly impact the future of our fields. The rich collection of ideas and projects also indicates that the applications of LLMs are not limited to materials science and chemistry but offer potential benefits to a wide range of scientific disciplines.
A novel cop olyme r based on supramolecular motif2,6-diaminopyridin e and water-soluble acrylamide, poly[N-(6-ace tamidopyridin-2-yl) acrylamide-co-acrylamide], was synthe-size d via rev ersible addi tion–fragmentation chain transfer (RAFT)polymerization with various monomer compositions. The thermo-respon sive behavior of the copolymers was studied by turbidime-try and dynamic light scattering (DLS). The obtained copolymersshowed an upper critical solution temperature (UCST)-typ e phasetransition behavior in water and electrolyte solution. The phasetransition temperature was found to increase with decreasingam ount of acrylamide in the copolymer and increasing concentra-tion of the solution. Furth ermore, the phase transition temperatureva ried in aqueous solutions of electrolytes according to the naturean d concentration of the electrolyte in accordance with theHoffmeister series. A dramatic solvent isotope effect on thetransition temperature was o bserved in this study, as the transitiontemperature was almost 10–12C higher in D2OthaninH2Oatthesame concentration and acrylamide co mposition. The size of theaggregates below the transition temperature was larger in D2Ocompared to that in H2O that can be explained by deuterium iso-tope effect. The thermoresponsive behavior of the copolymers wasalso investigated in different cell medium and found to be exhibitedUCST-type phase transition behavior in different cell medium.Such behavior of the copo lyme rs can be useful in many a pplica-tions including biomedical, microfluidics, optical materials, and indrug delivery.
AbstractThis work addresses the critical need for multifunctional materials and substrate‐independent high‐precision surface modification techniques that are essential for advancing microdevices and sensing elements. To overcome existing limitations, the versatility of mussel‐inspired materials (MIMs) is combined with state‐of‐the‐art multiphoton direct laser writing (DLW) microfabrication. In this way, 2D and 3D MIM microstructures of complex designs are demonstrated with sub‐micron to micron resolution and extensive post‐functionalization capabilities. This study includes polydopamine (PDA), mussel‐inspired linear, and dendritic polyglycerols (MI‐lPG and MI‐dPG), allowing their direct microstructure on the substrate of choice with the option to tailor the patterned topography and morphology in a controllable manner. The functionality potential of MIMs is demonstrated by successfully immobilizing and detecting single‐stranded DNA on MIM micropattern and nanoarray surfaces. In addition, easy modification of MIM microstructure with silver nanoparticles without the need of any reducing agent is shown. The methodology developed here enables the integration of MIMs in advanced applications where precise surface functionalization is essential.
2D evaluation of spectral LIBS data derived from heterogeneous materials using cluster algorithm
(2017)
Laser-induced Breakdown Spectroscopy (LIBS) is capable of providing spatially resolved element maps in regard to the chemical composition of the sample. The evaluation of heterogeneous materials is often a challenging task, especially in the case of phase boundaries. In order to determine information about a certain phase of a material, the need for a method that offers an objective evaluation is necessary. This paper will introduce a cluster algorithm in the case of heterogeneous building materials (concrete) to separate the spectral information of non-relevant aggregates and cement matrix. In civil engineering, the information about the quantitative ingress of harmful species like Cl−, Na+ and SO2−4 is of great interest in the evaluation of the remaining lifetime of structures (Millar et al., 2015; Wilsch et al., 2005). These species trigger different damage processes such as the alkali-silica reaction (ASR) or the chloride-induced corrosion of the reinforcement. Therefore, a discrimination between the different phases, mainly cement matrix and aggregates, is highly important (Weritz et al., 2006). For the 2D evaluation, the expectation-maximizationalgorithm (EM algorithm; Ester and Sander, 2000) has been tested for the application presented in this work. The method has been introduced and different figures of merit have been presented according to recommendations given in Haddad et al. (2014). Advantages of this method will be highlighted. After phase separation, non-relevant information can be excluded and only the wanted phase displayed. Using a set of samples with known and unknown composition, the EM-clustering method has been validated regarding to Gustavo González and Ángeles Herrador (2007).
Layer-by-layer additive manufacturing (AM) by means of laser-powder bed Fusion (L-PBF) offers many prospects regarding the design of lattice structures used, for example, in gas turbines. However, defects such as bulk porosity, Surface roughness, and re-entrant features are exacerbated in nonvertical structures, such as tilted struts. The characterization and quantification of these kinds of
defects are essential for the correct estimation of fracture and fatigue properties.
Herein, cylindrical struts fabricated by L-PBF are investigated by means of X-ray computed tomography (XCT), with the aim of casting light on the dependence of the three kinds of defects (bulk porosity, surface roughness, and re-entrant features) on the build angle. Innovative analysis methods are proposed to correlate shape and position of pores, to determine the angular-resolved Surface roughness, and to quantify the amount of re-entrant surface features, q. A meshing of the XCT surface enables the correlation of q with the classical Surface roughness Pa. This analysis leads to the conclusion that there is a linear correlation between q and Pa. However, it is conjectured that there must be a threshold of surface roughness, below which no re-entrant features can be build.