Amyloid peptides are the main component of one of the characteristic pathological hallmarks of Alzheimer's disease (AD): senile plaques. According to the amyloid cascade hypothesis, amyloid peptides ...may play a central role in the sequence of events that leads to neurodegeneration. However, there are other factors, such as oxidative stress, that may be crucial for the development of the disease. In the present paper, we show that it is possible, by using Fourier tranform infrared (FTIR) microscopy, to co-localize amyloid deposits and lipid peroxidation in tissue slides from patients affected by Alzheimer's disease. Plaques and lipids can be analyzed in the same sample, making use of the characteristic infrared bands for peptide aggregation and lipid oxidation. The results show that, in samples from patients diagnosed with AD, the plaques and their immediate surroundings are always characterized by the presence of oxidized lipids. As for samples from non-AD individuals, those without amyloid plaques show a lower level of lipid oxidation than AD individuals. However, it is known that plaques can be detected in the brains of some non-AD individuals. Our results show that, in such cases, the lipid in the plaques and their surroundings display oxidation levels that are similar to those of tissues with no plaques. These results point to lipid oxidation as a possible key factor in the path that goes from showing the typical neurophatological hallmarks to suffering from dementia. In this process, the oxidative power of the amyloid peptide, possibly in the form of nonfibrillar aggregates, could play a central role.
BACKGROUND AND AIMS: Phosphorus (P) is an essential nutrient for plants but its low availability often necessitates amendments for agronomical issues. Objectives were to determine P spatial ...distribution and speciation that remain poorly understood in cultivated soils. METHODS: Aquic Argiudoll soil samples developed on a calcareous loam glacial till were collected from experimental plots submitted to contrasting crop rotations and amendments. Micro-X-ray fluorescence (μ-XRF) maps were collected on undisturbed samples. X-ray absorption near edge structure (XANES) spectra were collected on bulk samples and on fractions thereof, and on points of interests selected from μ-XRF maps. Results were compared with chemical analyses and extraction techniques results. RESULTS: Chemical analyses show variations in total and exchangeable P contents depending on the samples but no significant difference is observed in terms of P distribution and speciation. P distribution is dominated by a low-concentration diffuse background with a minor contribution from minute hot spots. P speciation is dominated by phosphate groups bound to clay-humic complexes. No modification of P distribution and speciation is observed close to roots. CONCLUSIONS: This study evidenced minor effect of cropping and fertilizing practices on P speciation in cultivated soils. Despite analytical challenges, the combined use of μ-XRF and XANES provides relevant information on P speciation in heterogeneous soil media.
The increased use of engineered nanomaterials (ENMs) in commercial products and the continuous development of novel applications, is leading to increased intentional and unintentional release of ENMs ...into the environment with potential negative impacts. Particularly, the partition of nanoparticles (NPs) to waste water treatment plant (WWTP) sludge represents a potential threat to agricultural ecosystems where these biosolids are being applied as fertilizers. Moreover, several applications of ENMs in agriculture and soil remediation are suggested. Therefore, detailed risk assessment should be done to evaluate possible secondary negative impacts. The impact of ENMS on plants as central component of ecosystems and worldwide food supply is of primary relevance. Understanding the fate and physical and chemical modifications of NPs in plants and their possible transfer into food chains requires specialized analytical techniques. Due to the importance of both chemical and physical factors to consider for a better understanding of ENMs behavior in complex matrices, these materials can be considered a new type of analyte. An ideal technique should require minimal sample preparation, be non-destructive, and offer the best balance between sensitivity, chemical specificity, and spatial resolution. Synchrotron radiation (SR) techniques are particularly adapted to investigate localization and speciation of ENMs in plants. SR X-ray fluorescence mapping (SR-XFM) offers multi-elemental detection with lateral resolution down to the tens of nm, in combination with spatially resolved X-ray absorption spectroscopy (XAS) speciation. This review will focus on important methodological aspects regarding sample preparation, data acquisition and data analysis of SR-XFM/XAS to investigate interactions between plants and ENMs.
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•Uptake and transport of ENMs in plants can be studied with synchrotron based micro/nanoprobes.•X-ray fluorescence maps and absorption spectroscopy provide elements distribution and speciation.•Sample preparation should preserve morphology, elements distribution and speciation at all scales.•Cryogenic conditions maintain samples close to in-vivo state and reduce radiation damage.•Data analysis software should handle large hyperspectral data sets.
In Heritage Science, the evaluation of stone consolidation treatments by investigating the nature of in situ newly formed products and their penetration depth within the consolidated matrix is a ...grand challenge. A number of analytical methods have been proposed, but, currently, most of them are not able to supply a full overview of the spatial, structural and compositional information of the newly formed crystalline and amorphous phases with a submicrometric lateral resolution. Here, we examined, the capabilities of synchrotron radiation (SR)-based two-dimensional X-ray absorption near-edge structure (2D-XANES) spectroscopy at Ca K-edge for determining the structural and compositional properties of the compounds formed after the application of a calcium acetoacetate-based consolidant on a porous carbonatic stone (limestone) and for investigating their stratigraphic distribution at the submicrometric scale length. We evaluated advantages and drawbacks of three Ca K-edge 2D-XANES-based approaches: (i) transmission mode full-field-XANES (FF-XANES) imaging; (ii) micro-X-ray fluorescence (μ-XRF) mapping above the Ca K-edge combined with the acquisition of XRF mode μ-XANES spectra at a limited number of spots; (iii) full-spectral µ-XANES (FS µ-XANES) mapping in XRF mode and its variant called selectively induced X-ray emission spectroscopy (SIXES) mapping. Overall, Ca K-edge 2D-XANES spectroscopy provided accurate qualitative and semi-quantitative information on the newly formed calcium carbonates (i.e., amorphous calcium carbonate, vaterite and calcite) and their stratigraphic distribution at the submicrometric scale, thus opening a new scenario to study the carbonatation process of calcium-based consolidants in limestones.
This paper accounts for the diagnostic campaign aimed at understanding the phenomenon of black stains appeared on the passepartout close to the margins of Folio 843 of Leonardo da Vinci's Codex ...Atlanticus. Previous studies excluded microbiological deterioration processes. The study is based on a multi-analytical approach, including non-invasive imaging measurements of the folio, micro-imaging and synchrotron spectroscopy investigations of passepartout fragments at different magnifications and spectral ranges. Photoluminescence hyperspectral and lifetime imaging highlighted that black stains are not composed of fluorescent materials. μATR-FTIR imaging of fragments from the passepartout revealed the presence of a mixture of starch and PVAc glues localized only in the stained areas close to the margin of the folio. FE-SEM observations showed that the dark stains are localized inside cavities formed among cellulose fibers, where an accumulation of inorganic roundish particles (∅100-200 nm in diameter size), composed of Hg and S, was detected. Finally, by employing synchrotron μXRF, μXANES and HR-XRD analyses it was possible to identify these particles as metacinnabar (β-HgS). Further research is needed to assess the chemical process leading to the metacinnabar formation in the controlled conservation condition of Leonardo's Codex.
Revealing metallic ink in Herculaneum papyri Brun, Emmanuel; Cotte, Marine; Wright, Jonathan ...
Proceedings of the National Academy of Sciences - PNAS,
04/2016, Letnik:
113, Številka:
14
Journal Article
Recenzirano
Odprti dostop
Writing on paper is essential to civilization, as Pliny the Elder remarks in his Natural History, when he describes the various types of papyri, the method of manufacturing them, and all that ...concerns writing materials in the mid-first century AD. For this reason, a rigorous scientific study of writing is of fundamental importance for the historical understanding of ancient societies. We show that metallic ink was used several centuries earlier than previously thought. In particular, we found strong evidence that lead was intentionally used in the ink of Herculaneum papyri and discuss the possible existence of ruled lines traced on the papyrus texture. In addition, the metallic concentrations found in these fragments deliver important information in view of optimizing future computed tomography (CT) experiments on still-unrolled Herculaneum scrolls to improve the readability of texts in the only surviving ancient Greco-Roman library.
The European Synchrotron Radiation Facility (ESRF) has recently commissioned the new Extremely Brilliant Source (EBS). The gain in brightness as well as the continuous development of beamline ...instruments boosts the beamline performances, in particular in terms of accelerated data acquisition. This has motivated the development of new access modes as an alternative to standard proposals for access to beamtime, in particular via the "block allocation group" (BAG) mode. Here, we present the recently implemented "historical materials BAG": a community proposal giving to 10 European institutes the opportunity for guaranteed beamtime at two X-ray powder diffraction (XRPD) beamlines-ID13, for 2D high lateral resolution XRPD mapping, and ID22 for high angular resolution XRPD bulk analyses-with a particular focus on applications to cultural heritage. The capabilities offered by these instruments, the specific hardware and software developments to facilitate and speed-up data acquisition and data processing are detailed, and the first results from this new access are illustrated with recent applications to pigments, paintings, ceramics and wood.
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•New methods for the preparation of thin sections from painting fragment, in particular for FTIR microscopy.•SES method: embedding-free approach, suitable for the preparation of fresh ...or rich-binder paintings.•ARE method: use of an AgCl barrier coating to prevent the penetration/contamination of embedding resin.•Application to real cases: a deeper insight into ancient manufacturing or degradation processes of historical artefacts.
For more than a century, the analyses of painting fragments have been carried out mainly through the preparation of thick resin-embedded cross-sections. Taking into account the development of innovative micro-analytical imaging techniques, alternatives to this standard preparation method are considered. Consequently, dedicated efforts are required to develop preparation protocols limiting the risks of chemical interferences (solubilisation, reduction/oxidation or other reactions) which modify the sample during its preparation, as well as the risks of analytical interferences (overlap of detected signals coming from the sample and from materials used in the preparation). This study focuses particularly on the preparation of thin-sections (1–20μm) for single or combined fourier transform infrared (FTIR) spectroscopy and X-ray 2D micro-analysis. A few strategies specially developed for the μFTIR analysis of painting cross-sections have already been reported and their potential extrapolation to the preparation of thin-sections is discussed. In addition, we propose two new specific methods: (i) the first is based on a free-embedding approach, ensuring a complete chemical and analytical neutrality. It is illustrated through application on polymeric design objects corpus; (ii) the second is based on a barrier coating approach which strengthens the sample and avoids the penetration of the resin into the sample. The barrier coating investigated is a silver chloride salt, an infrared transparent material, which remains malleable and soft after pellet compression, enabling microtoming. This last method was successfully applied to the preparation of a fragment from a gilded Chinese sculpture (15th C.) and was used to unravel a unique complex stratigraphy when combining μFTIR and μXRF.
Metallic implants are frequently used in medicine to support and replace degenerated tissues. Implant loosening due to particle exposure remains a major cause for revision arthroplasty. The exact ...role of metal debris in sterile peri‐implant inflammation is controversial, as it remains unclear whether and how metals chemically alter and potentially accumulate behind an insulating peri‐implant membrane, in the adjacent bone and bone marrow (BM). An intensively focused and bright synchrotron X‐ray beam allows for spatially resolving the multi‐elemental composition of peri‐implant tissues from patients undergoing revision surgery. In peri‐implant BM, particulate cobalt (Co) is exclusively co‐localized with chromium (Cr), non‐particulate Cr accumulates in the BM matrix. Particles consisting of Co and Cr contain less Co than bulk alloy, which indicates a pronounced dissolution capacity. Particulate titanium (Ti) is abundant in the BM and analyzed Ti nanoparticles predominantly consist of titanium dioxide in the anatase crystal phase. Co and Cr but not Ti integrate into peri‐implant bone trabeculae. The characteristic of Cr to accumulate in the intertrabecular matrix and trabecular bone is reproducible in a human 3D in vitro model. This study illustrates the importance of updating the view on long‐term consequences of biomaterial usage and reveals toxicokinetics within highly sensitive organs.
Spatially micron‐ and nanoresolved synchrotron X‐ray fluorescence analyses of peri‐implant cancellous bone reveal specific distribution and accumulation patterns of metals released from alloys frequently used in knee and hip arthroplasty. These new insights of the local toxicokinetics of metallic debris prove that cobalt, chromium, and titanium exposure also occurs behind the insulating implant membrane, in the bone and bone marrow.
Abstract
This research aims to understand colouring technologies in 5th–7th centuries glass imported to Atlantic Britain by correlating the iron (Fe) and manganese (Mn) ratios and oxidation states ...with colour. Despite having a similar matrix chemical composition and concentrations of Fe and Mn oxides, these vessels display different colours (from green to yellow/amber, sometimes with purple streaks). Colour changes can be induced by controlling the reduction-oxidation reactions that occur during glass production, which are influenced by the raw materials, furnace and melt atmosphere, and recycling. To evaluate these parameters, reference glasses were prepared, following the composition of Late Antique archaeological glass recovered from Tintagel (UK) and Whithorn (UK). A corpus of archaeological and experimental glass samples was analysed using bulk Fe and Mn K-edge x-ray absorption near edge structure (XANES) spectroscopy, micro-XANES and micro x-ray fluorescence (
μ
-XRF) at beamline ID21, at the European Synchrotron Radiation Facility. Fe and Mn XANES spectra of the archaeological glass indicate that Fe and Mn are in a similar oxidation state in all the yellow samples, predominantly Fe
3+
and Mn
2+
. No detectable difference in Mn and Fe oxidation state occurs in the purple streaks compared to the yellow glass bulk but
μ
-XRF maps of the distribution of Fe and Mn show that Mn is more concentrated in the purple streaks. This indicates that the purple colour of the streaks is mainly due to a higher Mn/Fe ratio and persistence of more oxidised manganese in the purple areas, even though it is difficult to detect. Many archaeological fragments appear pale green in transmitted light but amber in reflected light. XANES studies detected the presence of surface layers where manganese is more oxidised. This layer is believed to scatter transmitted and reflected light differently and might be responsible for the optical features of the archaeological glass.
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