#Sulphur variations in annually #layered #stalagmites using benchtop micro #XRF
#xray #fluorescence is a great tool for #geochemistry and #paleoclimate studies!
#science #spectra #traceelements
https://www.sciencedirect.com/science/article/abs/pii/S0584854722000106
This week in the student's practical course:
**X-Ray Fluorescence Analysis**
One task was to analyze historical Roman coins and evaluate if they are genuine or not.
Spot the counterfeit... 😀
#XRF #AnalyticalChemistry #university #teaching #PracticalCourse #XRayFluorescence
☕ Here's a bit of technical content from me - today a deep dive on #baseline correction methods.
📈 Baseline correction is a preprocessing technique to remove background signal and isolate peaks in hashtag#spectroscopy data.
📝 In my recent post I discuss two methods:
1. Wavelet transform (WT) - Decomposes signal into components at different frequencies. Lowest frequency component represents baseline and can be removed.
2. Asymmetric least squares (ALS) - Fits a smooth baseline function, penalising positive deviations more than negative ones.
TL;DR: WT method is intuitive but can distort peaks. ALS produces better results.
🔎 Both methods are applied on a #Raman spectrum and an X-ray fluorescence (#XRF) spectrum. ALS gives a cleaner baseline correction and it's effective for removing broad, slowly varying background while preserving sharper spectral features.
#chemometrics #Python #MachineLearning #wavelets #regression
https://nirpyresearch.com/two-methods-baseline-correction-spectral-data/
New #research: Can we trace development stages and ecology of a #permafrost thaw lake throughout the Holocene? Using an innovative combination of sedimentary proxies (ancient #DNA, #diatoms, #XRF), @Iza_bai et al. show: Yes, we can!
Long-term evolution of Central #Yakutia's vital #alaas #thermokarst lakes is traced throughout past millennia. This may help understand future pathways of culturally important lake systems!
In Central Yakutia (Siberia) livelihoods of local communities depend on alaas (thermokarst depression) landscapes and the lakes within. Development and dynamics of these alaas lakes are closely connected to climate change, permafrost thawing, catchment conditions, and land use. To reconstruct lake development throughout the Holocene we analyze sedimentary ancient DNA (sedaDNA) and biogeochemistry from a sediment core from Lake Satagay, spanning the last c. 10,800 calibrated years before present (cal yrs BP). SedaDNA of diatoms and macrophytes and microfossil diatom analysis reveal lake formation earlier than 10,700 cal yrs BP. The sedaDNA approach detected 42 amplicon sequence variants (ASVs) of diatom taxa, one ASV of Eustigmatophyceae (Nannochloropsis), and 12 ASVs of macrophytes. We relate diatom and macrophyte community changes to climate-driven shifts in water level and mineral and organic input, which result in variable water conductivity, in-lake productivity, and sediment deposition. We detect a higher lake level and water conductivity in the Early Holocene (c. 10,700–7000 cal yrs BP) compared to other periods, supported by the dominance of Stephanodiscus sp. and Stuckenia pectinata. Further climate warming towards the Mid-Holocene (7000–4700 cal yrs BP) led to a shallowing of Lake Satagay, an increase of the submerged macrophyte Ceratophyllum, and a decline of planktonic diatoms. In the Late Holocene (c. 4700 cal yrs BP–present) stable shallow water conditions are confirmed by small fragilarioid and staurosiroid diatoms dominating the lake. Lake Satagay has not yet reached the final stage of alaas development, but satellite imagery shows an intensification of anthropogenic land use, which in combination with future warming will likely result in a rapid desiccation of the lake.
A #research team at the #University of Göttingen [#Physics #Optics] has developed a new method to produce #Xray images in #colour. In the past, the only way to spatially determine the #chemical #composition of a sample using X-ray #fluorescence [#XRF] was to focus X-rays and scan the whole sample. This is time-consuming and expensive. Scientists have now developed an approach that allows an image of a large area to be produced from a single exposure.
published in Optica: https://doi.org/10.1364/OPTICA.477809
Ein Forschungsteam [#Forschung #Physik #Optik] der #Universität #Göttingen hat ein neues Verfahren für Röntgenfarbaufnahmen [#Röntgen #Xray #Xrays] entwickelt. Um nicht nur die chemischen #Elemente einer Probe durch Röntgenfluoreszenzanalyse [#Fluoreszenz #XRF] zu bestimmen, sondern auch deren räumliche Verteilung, muss bislang die genutzte #Röntgenstrahlung fokussiert und die Probe aufwendig abgerastert werden.
PM: https://uni-goettingen.de/de/3240.html?id=6960
Publikation @ Optica: https://doi.org/10.1364/OPTICA.477809
ASX Mkt. Sensitive
Niels de Winter
Markus Witzler
Daniel Pelliccia
Dr. Ramesh Glückler
Markus Osterhoff
Sebastian Breitenbach