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Ključne besede: aluminum-silicon cast alloys, field testing, scanning electron microscopy, x-ray photoelectron spectroscopy, marine immersion, Adriatic Sea
Objavljeno v DiRROS: 25.04.2025; Ogledov: 141; Prenosov: 61
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Ključne besede: legumes, NIR, spectroscopy, plant genetic resources, pre-breeding collection, protein content, seed traits
Objavljeno v DiRROS: 25.02.2025; Ogledov: 235; Prenosov: 105
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Povzetek: In this work, operando sulfur X-ray emission measurementson a Li−S battery cathode were performed using a laboratory setup as analternative to more common synchrotron radiation based absorptionstudies. Photoexcitation by an X-ray tube was used. Valence-to-core Kβ X-ray emission spectra were recorded with a wavelength dispersive crystalspectrometer in von Hamos geometry, providing excellent energyresolution and good detection efficiency. The setup was used to recordex situ S Kβ emission spectra from S cathodes from the Li−S battery andalso under operando conditions. Average S oxidation state within thebattery cathode during battery cycling was determined from the shape ofthe Kβ emission spectra. A more detailed S species characterization wasperformed by fitting a linear combination of previously measuredlaboratory synthesized standards to the measured spectra. Relative amounts of different S species in the cathode were determinedduring the cycling of the Li−S battery. The main advantage of X-ray emission spectroscopy is that it can be performed onconcentrated samples with S loading comparable to a real battery. The approach shows great promise for routine laboratory analysisof electrochemical processes in Li−S batteries and other sulfur-based systems under operando conditions.
Ključne besede: X-ray emission spectroscopy, lithium−sulfur batteries, operando measurements, oxidation state, von Hamos spectrometer
Objavljeno v DiRROS: 19.12.2024; Ogledov: 320; Prenosov: 148
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Povzetek: Well-characterized reference materials support harmonization and accuracy when conducting nucleic acid-based tests (such as qPCR); digital PCR (dPCR) can measure the absolute concentration of a specific nucleic acid sequence in a background of non-target sequences, making it ideal for the characterization of nucleic acid-based reference materials. National Metrology Institutes are increasingly using dPCR to characterize and certify their reference materials, as it offers several advantages over indirect methods, such as UV-spectroscopy. While dPCR is gaining widespread adoption, it requires optimization and has certain limitations and considerations that users should be aware of when characterizing reference materials. This review highlights the technical considerations of dPCR, as well as its role when developing and characterizing nucleic acid-based reference materials.
Ključne besede: digital PCR, dPCR, reference materials, UV-spectroscopy
Objavljeno v DiRROS: 03.06.2024; Ogledov: 872; Prenosov: 302
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Povzetek: Introduction: The global burden of diabetes mellitus is escalating, and more efficient investigative strategies are needed for a deeper understanding of underlying pathophysiological mechanisms. The crucial role of skeletal muscle in carbohydrate and lipid metabolism makes it one of the most susceptible tissues to diabetes-related metabolic disorders. In tissue studies, conventional histochemical methods have several technical limitations and have been shown to inadequately characterise the biomolecular phenotype of skeletal muscle to provide a holistic view of the pathologically altered proportions of macromolecular constituents. Materials and methods: In this pilot study, we examined the composition of five different human skeletal muscles from male donors diagnosed with type 2 diabetes and non-diabetic controls. We analysed the lipid, glycogen, and collagen content in the muscles in a traditional manner with histochemical assays using different staining techniques. This served as a reference for comparison with the unconventional analysis of tissue composition using Fourier-transform infrared spectroscopy as an alternative methodological approach. Results: A thorough chemometric post-processing of the infrared spectra using a multi-stage spectral decomposition allowed the simultaneous identification of various compositional details from a vibrational spectrum measured in a single experiment. We obtained multifaceted information about the proportions of the different macromolecular constituents of skeletal muscle, which even allowed us to distinguish protein constituents with different structural properties. The most important methodological steps for a comprehensive insight into muscle composition have thus been set and parameters identified that can be used for the comparison between healthy and diabetic muscles. Conclusion: We have established a methodological framework based on vibrational spectroscopy for the detailed macromolecular analysis of human skeletal muscle that can effectively complement or may even serve as an alternative to histochemical assays. As this is a pilot study with relatively small sample sets, we remain cautious at this stage in drawing definitive conclusions about diabetes-related changes in skeletal muscle composition. However, the main focus and contribution of our work has been to provide an alternative, simple and efficient approach for this purpose. We are confident that we have achieved this goal and have brought our methodology to a level from which it can be successfully transferred to a large-scale study that allows the effects of diabetes on skeletal muscle composition and the interrelationships between the macromolecular tissue alterations due to diabetes to be investigated.
Ključne besede: diabetes mellitus, skeletal muscle, metabolism, macromulecular composition, infrared spectroscopy, multivariate analysis, histochemical assays
Objavljeno v DiRROS: 11.01.2024; Ogledov: 1081; Prenosov: 402
Celotno besedilo (1,71 MB)
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