TY - JOUR A1 - Stolar, Tomislav A1 - Bayram, Dilara A1 - May, Anastasia A1 - Sundermann, Remie A1 - Prinz, Carsten A1 - Meyer, Klas A1 - Myxa, Anett A1 - Falkenhagen, Jana A1 - Emmerling, Franziska T1 - Selective mechanochemical conversion of post-consumer polyethylene terephthalate waste into hcp and fcu UiO-66 metal–organic frameworks N2 - Single-use plastics strongly contribute to plastic pollution, and less than 10% of plastic waste is recycled globally. Here, we present a selective mechanochemical protocol for converting post-consumer polyethylene terephthalate (PET) transparent bottles and coloured textile waste into the porous metal–organic framework (MOF) UiO-66 materials. We used time-resolved in situ (TRIS) synchrotron powder X-ray diffraction and Raman spectroscopy to monitor the depolymerization of PET during ball milling. To convert disodium terephthalate to UiO-66, we developed base and base-free synthetic routes that lead to fcu and hcp UiO-66 phases, respectively, including the first ever synthesis of hcp UiO-66 by mechanochemistry. Our results demonstrate the potential of mechanochemistry to selectively access fcu and hcp UiO-66 phases using post-consumer PET waste. KW - Mechanochemistry PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-653958 DO - https://doi.org/10.1039/D4MR00126E SN - 2976-8683 SP - 1 EP - 8 PB - Royal Society of Chemistry (RSC) AN - OPUS4-65395 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bruno, Francesco A1 - Fiorucci, Letizia A1 - Vignoli, Alessia A1 - Meyer, Klas A1 - Maiwald, Michael A1 - Ravera, Enrico T1 - pyIHM: Indirect Hard Modeling, in Python N2 - NMR is a powerful analytical technique that combines an exquisite qualitative power, related to the unicity of the spectra of each molecule in a mixture, with an intrinsic quantitativeness, related to the fact that the integral of each peak only depends on the number of nuclei (i.e., the amount of substance times the number of equivalent nuclei in the signal), regardless of the molecule. Signal integration is the most common approach in quantitative NMR but has several drawbacks (vide infra). An alternative is to use hard modeling of the peaks. In this paper, we present pyIHM, a Python package for the quantification of the components of NMR spectra through indirect hard modeling, and we discuss some numerical details of the implementation that make this approach robust and reliable. KW - Algorithms KW - Chemical Structure KW - Deconvolution KW - Mixtures KW - NMR spectroscopy PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626793 DO - https://doi.org/10.1021/acs.analchem.4c06484 SN - 1520-6882 VL - 97 IS - 8 SP - 4598 EP - 4605 PB - ACS Publications CY - Washington D.C. AN - OPUS4-62679 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Golub, Tino Petar A1 - Meyer, Klas A1 - Paul, Andrea A1 - Kipphardt, Heinrich A1 - Tuma, Dirk T1 - Exploring the potential of a setup for combined quantification of hydrogen in natural gas – Raman and NMR spectroscopy N2 - An accurate measurement of the amount fraction of hydrogen in gas mixtures is mandatory for practical applications, requiring methods that are fast, continuous, robust, and cost-effective. This study compares the performance of Raman and benchtop NMR process spectroscopy for determining the hydrogen amount fraction in gas mixtures. A setup was designed to integrate both techniques, enabling measurements of the same sample. Tests were conducted with gravimetrically prepared gas mixtures of reference quality ranging from 1.20 cmol/mol to 85.83 cmol/mol of hydrogen. The results demonstrate that Raman spectroscopy provides superior performance, with a minimal root mean square error (RMSE) of 0.22 cmol/mol and excellent linearity. In contrast, benchtop NMR spectroscopy faced challenges, such as overlapping peaks and longer measurement times, resulting in a higher RMSE of 0.71 cmol/mol. Raman spectroscopy proves to be particularly well-suited for practical applications due to its high accuracy and linearity. Meanwhile, benchtop NMR spectroscopy holds potential for future enhancements through ongoing technological advances, such as higher magnetic field strengths. In summary, the results from our study indicate that Raman spectroscopy is already a serviceable method for precise hydrogen quantification, whereas benchtop NMR spectroscopy can be attributed potential for future applications. KW - Hydrogen amount fraction KW - Raman spectroscopy KW - NMR spectroscopy KW - Field applicability PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610093 DO - https://doi.org/10.1016/j.saa.2024.125087 SN - 1386-1425 VL - 325 SP - 1 EP - 9 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-61009 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiele, Isabel A1 - Weiske, Björn A1 - Riedel, Sebastian L. A1 - Meyer, Klas T1 - On-line monitoring of polyhydroxyalkanoate extraction by low-field nuclear magnetic resonance spectroscopy N2 - The use of low-field nuclear magnetic resonance (NMR) spectroscopy enables real-time reaction monitoring in contrast to time-consuming gas chromatography or off-line high-field NMR measurements. In this study, NMR spectroscopy is demonstrated as a novel process analytical technology (PAT) tool in the downstream processing of polyhydroxyalkanoate (PHA) biopolymers. On-line NMR spectroscopy measurements were performed using a Spinsolve 43 Carbon Ultra instrument in a fully automated mode with a flow-assembly based on PTFE tubing. Single-scan NMR spectra were acquired for real-time monitoring of the extraction process of the PHA copolymer poly(hydroxybutyrate-co-hydroxyhexanoate) with 13.5 mol.% hydroxyhexanoate [P(HB-co-13.5 mol.%HHx)] from Ralstonia eutropha biomass using chloroform or acetone as PHA solvents at lyophilized cell loadings of 20–120 g L􀀀 1. The reproducibility and reliability of low-field NMR spectroscopy was comparable to high-field NMR spectroscopy, with superior performance in terms of time. The correlation between the results of on-line monitoring using low-field NMR spectroscopy and off-line analysis using gas chromatography (GC) showed a correlation coefficient of >94 %. The versatility of low-field NMR spectroscopy for elucidating reaction kinetics, facilitating endpoint determination and accelerating extraction processes by maximizing solubility is highlighted as plateau values were reached within 6–10 min for chloroform and acetone, respectively. This novel low-field NMR spectroscopy application promotes a new monitoring approach for downstream PHA processing and supports process development and optimization. KW - Polyhydroxyalkanoate KW - Extraction KW - NMR KW - Ralstonia eutropha KW - Downstream processing PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624215 DO - https://doi.org/10.1016/j.polymdegradstab.2025.111188 SN - 1873-2321 VL - 233 SP - 1 EP - 10 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-62421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rahman, Navid A1 - Meyer, Klas A1 - Kraus, Werner A1 - Klapötke, Thomas M. A1 - Witkowski, Tomasz G. T1 - Synthesis, Characterization, and Evaluation of Energetic Properties of 1,2‐bis(5‐(Trifluoromethyl)‐4H‐1,2,4‐triazol‐3‐yl)Diazene N2 - A new azo‐bridged compound with triazole moieties featuring trifluoromethyl groups was synthesized, exhibiting encouraging properties in the field of energetic materials. The new compound was synthesized in two steps from common starting materials using cyclocondensation, followed by oxidation reaction. The compound was characterized using nuclear magnetic resonance spectroscopy, mass spectrometry, infrared spectroscopy, and single‐crystal X‐ray diffraction. Impact and friction sensitivities were measured using BAM standard methods, and electrostatic discharge (ESD) sensitivity was measured using an ESD device from OZM Research. Heat of formation was calculated computationally using the CBS‐4m method, density was determined by the pycnometric method, and energetic properties were calculated using Explo5 software. KW - Azo coupling KW - Energetic material KW - Insensitive KW - NMR spectroscopy KW - Triazole PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642454 DO - https://doi.org/10.1002/prep.70041 SN - 0721-3115 VL - 50 IS - 11-12 SP - 40 EP - 46 PB - Wiley-VHC CY - Weinheim AN - OPUS4-64245 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chandna, Sanjam A1 - Povolotsky, Tatyana L. A1 - Nie, Chuanxiong A1 - Schwartz, Sophia A1 - Wedepohl, Stefanie A1 - Quaas, Elisa A1 - Ludwig, Kai A1 - Boyakova, Yulia A1 - Bhatia, Sumati A1 - Meyer, Klas A1 - Falkenhagen, Jana A1 - Haag, Rainer A1 - Block, Stephan T1 - Lignin-Based Mucus-Mimicking Antiviral Hydrogels with Enzyme Stability and Tunable Porosity N2 - Mucus is a complex hydrogel that acts as a defensive and protective barrier in various parts of the human body. Therise in the level of viral infections has underscored the importance of advancing research into mucus-mimicking hydrogels for theefficient design of antiviral agents. Herein, we demonstrate the gram-scale synthesis of biocompatible, lignin-based virus-bindinginhibitors that reduce waste and ensure long-term availability. The lignin-based inhibitors are equipped with sulfate moieties, whichare known binding partners for many viruses, including SARS-CoV-2 and herpes viruses. In addition, cross-linking the synthesizedinhibitors yielded hydrogels that mimicked native mucus concerning surface functionality and rheology. The degree of sulfationexhibits a very strong impact on the mesh size distribution of the hydrogels, which provides a new means to fine-tune the steric andelectrostatic contributions of the virus−hydrogel interaction. This feature strongly impacts the sequestration capability of the lignin-based hydrogels, which is demonstrated by infection inhibition assays involving human herpes simplex virus 1, influenza A viruses,and the bacterium Escherichia coli (E. coli). These measurements showed a reduction in plaque-forming units (HSV-1) and colony-forming units (E. coli) by more than 4 orders of magnitude, indicating the potent inhibition by the lignin-based hydrogels KW - Lignin functionalization KW - Mucus-mimicking hydrogels PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625301 DO - https://doi.org/10.1021/acsami.4c18519 SP - 1 EP - 14 PB - American Chemical Society (ACS) CY - USA AN - OPUS4-62530 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiele, Isabel A1 - Santolin, Lara A1 - Meyer, Klas A1 - Machatschek, Rainhard A1 - Bölz, Uwe A1 - Tarazona, Natalia A. A1 - Riedel, Sebastian L. T1 - Microbially synthesized poly(hydroxybutyrate-co-hydroxyhexanoate) with low to moderate hydroxyhexanoate content: Properties and applications N2 - Plastic pollution is the biggest environmental concern of our time. Breakdown products like micro- and nanoplastics inevitably enter the food chain and pose unprecedented health risks. In this scenario, bio-based and biodegradable plastic alternatives have been given a momentum aiming to bridge a transition towards a more sustainable future. Polyhydroxyalkanoates (PHAs) are one of the few thermoplastic polymers synthesized 100 % via biotechnological routes which fully biodegrade in common natural environments. Poly(hydroxybutyrate-cohydroxyhexanoate) [P(HB-co-HHx)] is a PHA copolymer with great potential for the commodity polymers industry, as its mechanical properties can be tailored through fine-tuning of its molar HHx content. We have recently developed a strategy that enables for reliable tailoring of the monomer content of P(HB-co-HHx). Nevertheless, there is often a lack of comprehensive investigation of the material properties of PHAs to evaluate whether they actually mimic the functionalities of conventional plastics. We present a detailed study of P(HB-co-HHx) copolymers with low to moderate hydroxyhexanoate content to understand how the HHx monomer content influences the thermal and mechanical properties and to link those to their abiotic degradation. By increasing the HHx fractions in the range of 2 – 14 mol%, we impart an extension of the processing window and application range as the melting temperature (Tm) and glass temperature (Tg) of the copolymers decrease from Tm 165 ◦C to 126 ◦C, Tg 4 ◦C to − 5.9 ◦C, accompanied by reduced crystallinity from 54 % to 20 %. Elongation at break was increased from 5.7 % up to 703 % at 14 mol% HHx content, confirming that the range examined was sufficiently large to obtain ductile and brittle copolymers, while tensile strength was maintained throughout the studied range. Finally, accelerated abiotic degradation was shown to be slowed down with an increasing HHx fraction decreasing from 70 % to 55 % in 12 h. KW - Molecular Biology KW - General Medicine KW - Biochemistry KW - Structural Biology PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595636 DO - https://doi.org/10.1016/j.ijbiomac.2024.130188 VL - 263 SP - 1 EP - 9 PB - Elsevier B.V. AN - OPUS4-59563 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gugin, Nikita A1 - Yusenko, Kirill A1 - King, Andrew A1 - Meyer, Klas A1 - Al-Sabbagh, Dominik A1 - Villajos Collado, José Antonio A1 - Emmerling, Franziska T1 - Lighting up industrial mechanochemistry: Real-time in situ monitoring of reactive extrusion using energy-dispersive X-ray diffraction N2 - Mechanochemistry is an environmentally friendly synthetic approach that enables the sustainable production of a wide range of chemicals while reducing or eliminating the need for solvents. Reactive extrusion aims to move mechanochemistry from its conventional gram-scale batch reactions, typically performed in laboratory ball mills, to a continuous, large-scale process. Meeting this challenge requires in situ monitoring techniques to gain insights into reactive extrusion and its underlying processes. While the effectiveness of in situ Raman spectroscopy in providing molecular-level information has been demonstrated, our study uses energy-dispersive X-ray diffraction to monitor reactive extrusion in real time at the crystalline level. Our results provide previously unavailable control over the reactive extrusion process, promoting its perception as an industrially feasible green alternative to traditional solvent-based syntheses. KW - Mechanochemistry KW - Reactive extrusion KW - Green chemistry KW - In situ studies KW - Time-resolved in situ KW - TRIS KW - Synchrotron radiation KW - Scalable synthesis KW - Solid-state reactions KW - Reaction mechanisms PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613969 DO - https://doi.org/10.1016/j.chempr.2024.07.033 VL - 10 IS - 11 SP - 1 EP - 16 PB - Elsevier B.V. AN - OPUS4-61396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bornemann-Pfeiffer, Martin A1 - Meyer, Klas A1 - Lademann, J. A1 - Kraume, M. A1 - Maiwald, Michael T1 - Contributions towards variable temperature shielding for compact NMR instruments N2 - The application of compact NMR instruments to hot flowing samples or exothermically reacting mixtures is limited by the temperature sensitivity of permanent magnets. Typically, such temperature effects directly influence the achievable magnetic field homogeneity and hence measurement quality. The internal-temperature control loop of the magnet and instruments is not designed for such temperature compensation. Passive insulation is restricted by the small dimensions within the magnet borehole. Here, we present a design approach for active heat shielding with the aim of variable temperature control of NMR samples for benchtop NMR instruments using a compressed airstream which is variable in flow and temperature. Based on the system identification and surface temperature measurements through thermography, a model predictive control was set up to minimise any disturbance effect on the permanent magnet from the probe or sample temperature. This methodology will facilitate the application of variable-temperature shielding and, therefore, extend the application of compact NMR instruments to flowing sample temperatures that differ from the magnet temperature. KW - Benchtop NMR KW - Continuous Processes KW - Inline Analytics KW - Model Predictive Control KW - Process Analytical Tecnology KW - Temperature Control PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-579219 DO - https://doi.org/10.1002/mrc.5379 SN - 1097-458X SP - 1 EP - 10 PB - John Wiley & Sons Ltd. AN - OPUS4-57921 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Srivastava, Priyanka A1 - Tavernaro, Isabella A1 - Scholtz, Lena A1 - Genger, C. A1 - Welker, P. A1 - Schreiber, Frank A1 - Meyer, Klas A1 - Resch-Genger, Ute T1 - Dual color pH probes made from silica and polystyrene nanoparticles and their performance in cell studies N2 - Ratiometric green–red fluorescent nanosensors for fluorometrically monitoring pH in the acidic range were designed from 80 nm-sized polystyrene (PS) and silica (SiO2) nanoparticles (NPs), red emissive reference dyes, and a green emissive naphthalimide pH probe, analytically and spectroscopically characterized, and compared regarding their sensing performance in aqueous dispersion and in cellular uptake studies. Preparation of these optical probes, which are excitable by 405 nm laser or LED light sources, involved the encapsulation of the pH-inert red-fuorescent dye Nile Red (NR) in the core of self-made carboxylated PSNPs by a simple swelling procedure and the fabrication of rhodamine B (RhB)-stained SiO2-NPs from a silane derivative of pH-insensitive RhB. Subsequently, the custom-made naphthalimide pH probe, that utilizes a protonation-controlled photoinduced electron transfer process, was covalently attached to the carboxylic acid groups at the surface of both types of NPs. Fluorescence microscopy studies with the molecular and nanoscale optical probes and A549 lung cancer cells confirmed the cellular uptake of all probes and their penetration into acidic cell compartments, i.e., the lysosomes, indicated by the switching ON of the green naphthalimide fluorescence. This underlines their suitability for intracellular pH sensing, with the SiO2-based nanosensor revealing the best performance regarding uptake speed and stability. KW - Sensors KW - Silica and polystyrene nanoparticles KW - pH probe KW - Fluorescence spectroscopy KW - Cell studies KW - Dye KW - Particle synthesis PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569198 DO - https://doi.org/10.1038/s41598-023-28203-0 SN - 2045-2322 VL - 13 IS - 1 SP - 1321 EP - 1336 PB - Nature CY - London AN - OPUS4-56919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -