Fourier Transform Infrared Spectroscopic Imaging Research Articles

Accurate and visualiable discrimination of Chenpi age using 2D-CNN and Grad-CAM++ based on infrared spectral images

Dried tangerine peel (“Chenpi”), has numerous clinical and nutritional benefits, with its quality being significantly influenced by its storage age, referred to as “Chen Jiu Zhe Liang” in Chinese. Concequently, the rapid and accurate identification of Chenpi's age is important for consumers. In this study, Fourier transform infrared spectroscopy (FTIR) was employed to capture spectral images of Chenpi. These FTIR images were then analyzed using a two-dimensional convolutional neural networks (2D-CNN) model, achieving a discrimination accuracy of 97.92%. To address the “black box” nature of the 2D-CNN, Gradient-weighted Class Activation Mapping Plus Plus (Grad-CAM++) was utilized to highlight the important regions contributing to the model's performance. Additionally, six other machine learning models were developped using features identified by the 2D-CNN to validate their effectiveness. The results demonstrated that the combination of FTIR spectral images and 2D-CNN provides a highly effective method for accurately determining the age of Chenpi.

Inhibited hydrogen uptake in metasomatised cratonic eclogite

Water occurs in Earth’s interior mostly as trace hydroxyl in nominally anhydrous minerals. Clinopyroxene is known to be an important water carrier in the uppermost mantle, and eclogite, which forms a subordinate part of the cratonic lithosphere, contains some 50% of jadeite-rich clinopyroxene, making this potentially a significant H2O reservoir in the bulk lithospheric mantle. Mantle metasomatism, in particular by small-volume melts like kimberlite, is known to enrich the lithosphere in highly incompatible components, but its effect on H2O contents in cratonic eclogite remains unclear. We report H2O concentrations for clinopyroxene and garnet in eclogite and pyroxenite xenoliths from several African kimberlites, obtained by Fourier-Transform Infrared Spectroscopy (FTIR). Except one sample showing evidence for minor within-grain variability of H2O concentrations (< 15%), FTIR images demonstrate that H2O is homogeneously distributed in optically clear areas of clinopyroxene fragments mounted for this study. The samples were variably metasomatised by a kimberlite-like melt, as evidenced by elevated MgO contents and abundances of highly incompatible elements (e.g., Sr, Ce, Th). Although metasomatised eclogites and pyroxenites on average show higher H2O abundances than pristine ones, mantle metasomatism decreases the Al2O3 content in clinopyroxene, which is known to enhance hydrogen incorporation in this mineral. As a consequence, hydrogen incorporation is inhibited, and c(H2O) becomes increasingly decoupled from other highly incompatible components, such as LREE. Thus, eclogite – metasomatised or not - does not significantly contribute to the H2O inventory in the bulk cratonic mantle.

Interaction of polysaccharides on gel characteristics and protein microstructure of threadfin bream surimi gel

SummaryPolysaccharide is widely used to improve gel characteristics of surimi gel. The impacts of the polysaccharides tamarind kernel powder (TKP) and tapioca starch (TS) at concentrations of 0%, 2.5% and 5% by weight were investigated on protein conformation [Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM)] and textural characteristics (rheological property, gel strength, solubility, SH contents) of threadfin bream surimi gel. Higher G′ and G″ values were observed in surimi paste added with TKP. Hydrogen bonding increased at higher concentrations of polysaccharides. Addition of TS increased hydrophobic interaction and promoted alteration of the α‐helix to the β‐sheet in the gel structure, while adding TKP to surimi gel had the opposite effect. FTIR images indicated that higher concentrations of polysaccharides resulted in abundant specific polysaccharide functional groups. Microstructures of surimi gel with TKP exhibited an irregular network, with large voids leading to decreased gel strength, while addition of TS increased network density, promoting higher gel strength.

Increased HIF-2α activity in the nucleus pulposus causes intervertebral disc degeneration in the aging mouse spine.

Hypoxia-inducible factors (HIFs) are essential to the homeostasis of hypoxic tissues. Although HIF-2α, is expressed in nucleus pulposus (NP) cells, consequences of elevated HIF-2 activity on disc health remains unknown. We expressed HIF-2α with proline to alanine substitutions (P405A; P531A) in the Oxygen-dependent degradation domain (HIF-2αdPA) in the NP tissue using an inducible, nucleus pulposus-specific K19CreERT allele to study HIF-2α function in the adult intervertebral disc. Expression of HIF-2α in NP impacted disc morphology, as evident from small but significantly higher scores of degeneration in NP of 24-month-old K19CreERT; HIF-2αdPA (K19-dPA) mice. Noteworthy, comparisons of grades within each genotype between 14 months and 24 months indicated that HIF-2α overexpression contributed to more pronounced changes than aging alone. The annulus fibrosus (AF) compartment in the 14-month-old K19-dPA mice exhibited lower collagen turnover and Fourier transform-infrared (FTIR) spectroscopic imaging analyses showed changes in the biochemical composition of the 14- and 24-month-old K19-dPA mice. Moreover, there were changes in aggrecan, chondroitin sulfate, and COMP abundance without alterations in NP phenotypic marker CA3, suggesting the overexpression of HIF-2α had some impact on matrix composition but not the cell phenotype. Mechanistically, the global transcriptomic analysis showed enrichment of differentially expressed genes in themes closely related to NP cell function such as cilia, SLIT/ROBO pathway, and HIF/Hypoxia signaling at both 14- and 24-month. Together, these findings underscore the role of HIF-2α in the pathogenesis of disc degeneration in the aged spine.

New insights on collagen structural organization and spatial distribution around dental implants: a comparison between machined and laser-treated surfaces

BackgroundOne of the main factors for the osseointegration of dental implants is the development of an adequate soft tissue barrier, mainly composed by collagen, which protects the implant from bacterial development. The structural features of the peri-implant collagen are influenced by the implant components and, in particular, by the type of the surface. In the clinical practice, healing abutments are characterized by smooth surfaces, named machined. Recently, a new laser technique, Synthegra, has been developed to obtain a topography-controlled surface with micrometric regular pores that seems reducing the risk of peri-implantitis. Based on this background, this study aims investigating the structural organization and spatial distribution of collagen surrounding healing abutments characterized by laser-treated and machined surfaces.MethodsGingiva portions surrounding custom-made healing abutments (HA), characterized by alternated laser-treated and machined surfaces, were collected and analyzed by combining Fourier Transform InfraRed Imaging (FTIRI) spectroscopy, a non-invasive and high-resolution bidimensional analytical technique, with histological and multivariate analyses.ResultsMasson’s trichrome staining, specific for collagen, highlighted a massive presence of collagen in all the analyzed samples, evidencing a surface-related spatial distribution. The nature of collagen, investigated by the FTIRI spectroscopy, appeared more abundant close to the laser-treated surface, with a perpendicular disposition of the bundles respect to the HA; conversely, a parallel distribution was observed around the machined surface. A different secondary structure was also found, with a higher amount of triple helices and a lower quantity of random coils in collagen close to the laser treated surfaces.ConclusionsFTIRI spectroscopy demonstrates that the use of a laser treated transmucosal surface can improve the morphological organization of the peri-implant collagen, which presents a distribution more similar to that of natural teeth.Trial registration: This trial is registered with ClinicalTrials.gov Identifier: (Registration Number: NCT05754970). Registered 06/03/2023, retrospectively registered, https://clinicaltrials.gov/show/NCT05754970.

Spectroscopic imaging to assess biochemical alterations in liver carcinoma cells exposed to transition metals

Despite the invaluable role of transition metals in every living organism, it should be remembered that failure to maintain the proper balance and exceed the appropriate dose may have the opposite effect. In the era of such a popular and propagated need for supplementation in the media, one should bear in mind the harmful effects that may become the result of improper and excessive intake of transition metals.This article establishes the feasibility of Raman (RS) and Fourier-transform infrared (FT-IR) spectroscopic imaging at the single-cell level to investigate the cellular response to various transition metals. These two non-destructive and perfectly complementary methods allow for in-depth monitoring of changes taking place within the cell under the influence of the agent used. HepG2 liver carcinoma cells were exposed to chromium, iron, cobalt, molybdenum, and nickel at 1 and 2 mM concentrations.Spectroscopic results were further supported by biological evaluation of selected caspases concentration. The caspase- 3, 6, 8, 9, and 12 concentrations were determined with the use of the enzyme-linked immunosorbent assay (ELISA) method. This study shows the induction of apoptosis in the intrinsic pathway by all studied transition metals. Cellular metabolism alterations are induced by mitochondrial metabolism changes and endoplasmic reticulum (ER) metabolism variations. Moreover, nickel induces not only the intrinsic pathway of apoptosis but also the extrinsic pathway of this process.

Predicting the Secondary Structure of Proteins: A Deep Learning Approach

Background: The machine learning computation paradigm touched new horizons with the development of deep learning architectures. It is widely used in complex problems and achieved significant results in many traditional applications like protein structure prediction, speech recognition, traffic management, health diagnostic systems and many more. Especially, Convolution neural network (CNN) has revolutionized visual data processing tasks. Objective: Protein structure is an important research area in various domains extending from medical science, health sectors to drug designing. Fourier Transform Infrared Spectroscopy (FTIR) is the leading tool for protein structure determination. This review aims to study the existing deep learning approaches proposed in the literature to predict proteins' secondary structure and to develop a conceptual relation between FTIR spectra images and deep learning models to predict the structure of proteins. Methods: Various pre-trained CNN models are identified and interpreted to correlate the FTIR images of proteins containing Amide-I and Amide-II absorbance values and their secondary structure. Results: The concept of transfer learning is efficiently incorporated using the models like Visual Geometry Group (VGG), Inception, Resnet, and Efficientnet. The dataset of protein spectra images is applied as input, and these models act significantly to predict the secondary structure of proteins. Conclusion: As deep learning is recently being explored in this field of research, it worked remarkably in this application and needs continuous improvement with the development of new models.

Seasonal and spatial distribution of microplastics in sediments by FTIR imaging throughout a continuum lake - lagoon- beach from the Tunisian coast

Plastics pollution in marine environment has become an issue of increasing scientific concern. This work aims to study the temporal and spatial distribution of plastics in sediments from three different Tunisian ecosystems; Rimel Beach, Bizerta lagoon and Ichkeul lake. Sediment sampling was conducted in surface (2 cm) and depth (15 cm) during spring, summer and winter. Plastics debris were separated by size fractions: macro (>5 mm), meso (1–5 mm) and microplastics (<1 mm) to optimize the time necessary for their characterisation. Macroplastics and mesoplastics were identified using an IR Attenuated total reflectance (ATR) and microplastics with Imaging Fourier transform infrared spectroscopy (FTIR) spectroscopy after an optimized extraction protocol. Results indicate that, the lowest contamination degree with macroplastics was recorded in Ichkeul lake, 2 macro debris/m2 (marine protected area, national parc of Ichkeul). Mesoparticles were only detected in lagoon of Bizerte in large quantities (4900 item/kg of sediment in surface and 680 item/kg of sediment in depth) and were identified principally as paint products. For microplastics, the repartition was quite homogeneous between the three sites with an average abundance was 130.55 ± 65.61 items/kg for all seasons. The variations of microplastics abundances on the three sites could not be clearly related to the seasons. Whereas the polymer characterisation in the surface and depth sediments of the three studied areas were principally due to eight types of polymers (PVC, PET, PP, PE PS, Polyamide (PA) and polymeric methyl methacrylate (PMMA)) as reported in many other studies, surprisingly all MPs recovered in the study were smaller than 300 μm, >70 % being fragments. This study brings new results as regards to the state of plastic contamination in Tunisian coast and shows the importance of investigating different ecosystems in such studies.

Colon Cancer Grading Using Infrared Spectroscopic Imaging-Based Deep Learning

Tumor grade assessment is critical to the treatment of cancers. A pathologist typically evaluates grade by examining morphologic organization in tissue using hematoxylin and eosin (H&E) stained tissue sections. Fourier transform infrared spectroscopic (FT-IR) imaging provides an alternate view of tissue in which spatially specific molecular information from unstained tissue can be utilized. Here, we examine the potential of IR imaging for grading colon cancer in biopsy samples. We used a 148-patient cohort to develop a deep learning classifier to estimate the tumor grade using IR absorption. We demonstrate that FT-IR imaging can be a viable tool to determine colorectal cancer grades, which we validated on an independent cohort of surgical resections. This work demonstrates that harnessing molecular information from FT-IR imaging and coupling it with morphometry is a potential path to develop clinically relevant grade prediction models.

Biochemical Alterations in White Matter Tracts of the Aging Mouse Brain Revealed by FTIR Spectroscopy Imaging.

White matter degeneration in the central nervous system (CNS) has been correlated with a decline in cognitive function during aging. Ultrastructural examination of the aging human brain shows a loss of myelin, yet little is known about molecular and biochemical changes that lead to myelin degeneration. In this study, we investigate myelination across the lifespan in C57BL/6 mice using electron microscopy and Fourier transform infrared (FTIR) spectroscopic imaging to better understand the relationship between structural and biochemical changes in CNS white matter tracts. A decrease in the number of myelinated axons was associated with altered lipid profiles in the corpus callosum of aged mice. FTIR spectroscopic imaging revealed alterations in functional groups associated with phospholipids, including the lipid acyl, lipid ester and phosphate vibrations. Biochemical changes in white matter were observed prior to structural changes and most predominant in the anterior regions of the corpus callosum. This was supported by biochemical analysis of fatty acid composition that demonstrated an overall trend towards increased monounsaturated fatty acids and decreased polyunsaturated fatty acids with age. To further explore the molecular mechanisms underlying these biochemical alterations, gene expression profiles of lipid metabolism and oxidative stress pathways were investigated. A decrease in the expression of several genes involved in glutathione metabolism suggests that oxidative damage to lipids may contribute to age-related white matter degeneration.

Spatially resolved macromolecular orientation in biological tissues using FT-IR imaging

Fourier-transform infrared spectroscopy (FT-IR) in combination with machine learning and chemometrics is an intensively developed, powerful tool for investigation of tissue biochemical composition with simultaneous microscopic visualization. This nondestructive, information rich and label-free technique has been successfully applied in cancer diagnostics. During the development of a disease or inflammatory processes, not only the chemical composition of tissues changes, but also their spatial organization. FT-IR imaging with linear polarization can provide new and useful information about chemically-specific orientation of macromolecules. Here, we present results of spatial macromolecular orientation in human, pancreatic tissue using four-polarization FT-IR method. Despite the much more complex chemical structure of tissue compared to artificial materials such as fibrillar polymers, the obtained orientations of biomolecules in tissue agreed with theoretical prediction.

High-Resolution Fourier Transform Infrared (FT-IR) Spectroscopic Imaging for Detection of Lung Structures and Cancer-Related Abnormalities in a Murine Model.

Label-free molecular imaging is a promising utility to study tissues in terms of the identification of their compartments as well as chemical features and alterations induced by disease. The aim of this work was to assess if higher magnification of optics in the Fourier transform infrared (FT-IR) microscope coupled with the focal plane detector resulted in better resolution of lung structures and if the histopathological features correlated with clustering of spectral images. FT-IR spectroscopic imaging was performed on paraffinized lung tissue sections from mice with optics providing a total magnification of 61× and 36×. Then, IR images were subjected to unsupervised cluster analysis and, subsequently, cluster maps were compared with hematoxylin and eosin staining of the same tissue section. Based on these results, we observed minute features such as cellular compartments in single alveoli and bronchiole, blood cells and megakaryocytes in a vessel as well as atelectasis of the lung. In the case of the latter, differences in composition were also noted between the tissue from the non-cancerous and cancerous specimen. This study demonstrated the ability of high-definition FT-IR imaging to evaluate the chemical features of well-resolved lung structures that could complement the histological examination widely used in animal models of disease.

Hyperspectral characterization of the MSTO-211H cell spheroid model: A FPA–FTIR imaging approach

Multicellular spheroids are the new frontier for studying how the tumour micro-environment interferes with drug uptake and response, since they can reproduce a three-dimensional cellular organisation mimicking the behaviour of in vivo solid tissues. In this study, we exploited Focal Plane Array - Fourier Transform Infrared Imaging spectroscopy to characterize the biochemical features, in terms of distribution and composition of the meaningful macromolecules (lipids, proteins, sugars and nucleic acids), of malignant pleural mesothelioma spheroid sections, and, as further extent, to investigate the penetrating effects of cisplatin within the spheroid mass. The hyperspectral imaging analysis evidenced, in untreated spheroids, the occurrence of a replicative outer region and a hypoxic inner one, as suggested by the band area ratios related to lipid alkyl chains (2925/2960) and glycogen (1020/1650), which showed the highest values in the inner region. Moreover, the HCA spectroscopic images showed, after cisplatin treatment, an increase of the band area ratio related to lipid carbonyl ester moiety (1740/2925), suggesting the occurrence of lipid peroxidation; furthermore, the band area ratio related to nucleic acids (1240/1220) revealed a DNA fragmentation along all regions of spheroids that may be related to apoptotic mechanisms, whereas a reduction of the band area ratios related to glycogen and carbohydrates (1020/1650 and 1054/1650, respectively) appeared consistent with an inhibition of cell division. The few spectral differences between the outer and the inner regions of cisplatin-treated spheroids pointed out the diffuse penetrating effect of the drug.

Microstructure of cement paste subject to ambient pressure carbonation curing

This study investigated the microstructure of ordinary Portland cement paste subject to early age ambient pressure carbonation curing in a flexible enclosure. The high-pressure carbonation at 5 bar and the normal hydration were used as references. Both ambient-pressure and high-pressure carbonation was carried out with pure gas (99.9% CO2) for 12 h. It was found that ambient pressure carbonation could achieve comparable carbon uptake and strength gain as high pressure at both early and late age. Nevertheless, ambient carbonation was more economic and practical for precast products of different sizes and shapes. In order to examine this mechanism, X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), 29Si nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and nitrogen adsorption/desorption (NAD) were adopted to characterize the microstructural development after early carbonation curing under both ambient pressure and high pressure. Ambient pressure carbonation reaction took place more on the surface than in the core due to the limited CO2 diffusion so that the surface layer was more densified. The NAD results showed that ambient pressure performed better than high pressure in terms of reducing the cumulative pore volume and refining the capillary pore size. Ambient pressure could produce well crystalline carbonates as high pressure as deduced by XRD, TGA, FTIR and SEM images. The generation of calcium carbonate and its intermingling effect with hydration products were the main reasons for the strength gain and microstructural development of paste after early carbonation. Besides, SEM images showed that ambient pressure tended to produce calcium carbonates along the surface of C-S-H filling pore structure. As subsequent hydration proceeded, the increase of well crystalline carbonates was seen more in ambient pressure carbonation than high pressure based on TGA. NMR revealed that ambient pressure could enhance the polymerization of silicon in C-S-H promoting the early strength gain and maintain high Ca/Si ratio.

Simultaneous Characterization of Implant Wear and Tribocorrosion Debris within its Corresponding Tissue Response Using Infrared Chemical Imaging

Biotribology is one of the key branches in the field of artificial joint development. Wear and corrosion are among fundamental processes which cause material loss in a joint biotribological system; the characteristics of wear and corrosion debris are central to determining the in vivo bioreactivity. Much effort has been made elucidating the debris-induced tissue responses. However, due to the complexity of the biological environment of the artificial joint, as well as a lack of effective imaging tools, there is still very little understanding of the size, composition, and concentration of the particles needed to trigger adverse local tissue reactions, including periprosthetic osteolysis. Fourier transform infrared spectroscopic imaging (FTIR-I) provides fast biochemical composition analysis in the direct context of underlying physiological conditions with micron-level spatial resolution, and minimal additional sample preparation in conjunction with the standard histopathological analysis workflow. In this study, we have demonstrated that FTIR-I can be utilized to accurately identify fine polyethylene debris accumulation in macrophages that is not achievable using conventional or polarized light microscope with histological staining. Further, a major tribocorrosion product, chromium phosphate, can be characterized within its histological milieu, while simultaneously identifying the involved immune cell such as macrophages and lymphocytes. In addition, we have shown the different spectral features of particle-laden macrophages through image clustering analysis. The presence of particle composition variance inside macrophages could shed light on debris evolution after detachment from the implant surface. The success of applying FTIR-I in the characterization of prosthetic debris within their biological context may very well open a new avenue of research in the orthopedics community.

In Vitro Spectroscopy-Based Profiling of Urothelial Carcinoma: A Fourier Transform Infrared and Raman Imaging Study

Simple SummaryThe mortality and recurrence associated with urothelial carcinoma are high. High heterogeneity makes it hard to detect with currently available methods such as cytology and histology. We propose here vibrational spectroscopic imaging as an additional diagnostic tool for the classification of bladder cancer. Our study revealed that chemism-induced spectroscopic features of the cancer cells of various stages and invasiveness were specifically detected.Markers of bladder cancer cells remain elusive, which is a major cause of the low recognition of this malignant neoplasm and its recurrence. This implies an urgent need for additional diagnostic tools which are based on the identification of the chemism of bladder cancer. In this study, we employed label-free techniques of molecular imaging—Fourier Transform Infrared and Raman spectroscopic imaging—to investigate bladder cancer cell lines of various invasiveness (T24a, T24p, HT-1376, and J82). The urothelial HCV-29 cell line was the healthy control. Specific biomolecules discriminated spatial distribution of the nucleus and cytoplasm and indicated the presence of lipid bodies and graininess in some cell lines. The most prominent discriminators are the total content of lipids and sugar moieties as well as the presence of glycogen and other carbohydrates, un/saturated lipids, cytochromes, and a level of S-S bridges in proteins. The combination of the obtained hyperspectral database and chemometric methods showed a clear differentiation of each cell line at the level of the nuclei and cytoplasm and pointed out spectral signals which differentiated bladder cancer cells. Registered spectral markers correlated with biochemical composition changes can be associated with pathogenesis and potentially used for the diagnosis of bladder cancer and response to experimental therapies.

Perspectives on infrared spectroscopic imaging from cancer diagnostics to process analysis

This perspective paper discusses the recent and potential developments in the application of infrared spectroscopic imaging, with a focus on Fourier transform infrared (FTIR) spectroscopic imaging. The current state-of-the-art has been briefly reported, that includes recent trends and advances in applications of FTIR spectroscopic imaging to biomedical systems. Here, some new opportunities for research in the biomedical field, particularly for cancer diagnostics, and also in the engineering field of process analysis; as well as challenges in FTIR spectroscopic imaging are discussed. Current and future prospects that will bring spectroscopic imaging technologies to the frontier of advanced medical diagnostics and to process analytics in engineering applications will be outlined in this opinion paper.

Comparison of pyrolysis gas chromatography/mass spectrometry and hyperspectral FTIR imaging spectroscopy for the analysis of microplastics

Analysis of microplastics (MP) in environmental samples is an emerging field, which is performed with various methods and instruments based either on spectroscopy or thermoanalytical methods. In general, both approaches result in two different types of data sets that are either mass or particle number related. Depending on detection limits of the respective method and instrumentation the derived polymer composition trends may vary. In this study, we compare the results of hyperspectral Fourier-transform infrared (FTIR) imaging analysis and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) analysis performed on a set of environmental samples that differ in complexity and degree of microplastic contamination. The measurements were conducted consecutively, and on exactly the same sample. First, the samples were investigated with FTIR using aluminum oxide filters; subsequently, these were crushed, transferred to glass fiber filters, in pyrolysis cups, and measured via Py-GC/MS. After a general data harmonization step, the trends in MP contamination were thoroughly investigated with regard to the respective sample set and the derived polymer compositions. While the overall trends in MP contamination were very similar, differences were observed in the polymer compositions. Furthermore, polymer masses were empirically calculated from FTIR data and compared with the Py-GC/MS results. Here, a most plausible shape-related overestimation of the calculated polymer masses was observed in samples with larger particles and increased particle numbers. Taking into account the different measurement principles of both methods, all results were examined and discussed, and future needs for harmonization of intermethodological results were identified and highlighted.Graphical abstract

Tying up Loose Ends of Microplastic Pollution in the Arctic: Distribution from the Sea Surface through the Water Column to Deep-Sea Sediments at the HAUSGARTEN Observatory.

Recent studies have shown that despite its remoteness, the Arctic region harbors some of the highest microplastic (MP) concentrations worldwide. Here, we present the results of a sampling campaign to assess the vertical distribution of MP particles (>11 μm) at five stations of the HAUSGARTEN observatory. Water column samples were taken with large volume pumps by filtering 218-561 L of seawater at two to four depth strata (near-surface, ∼300 m, ∼1000 m, and above seafloor), and sediment samples were taken with a multiple corer. MP concentrations in the water column ranged between 0 and 1287 N m-3 and in the sediment from 239 to 13 331 N kg-1. Fourier transform infrared spectroscopy (FTIR) imaging with automated data analysis showed that polyamide (39%) and ethylene-propylene-diene rubber (23%) were the most abundant polymers within the water samples and polyethylene-chlorinated (31%) in sediments. MPs ≤ 25 μm accounted for more than half of the synthetic particles in every sample. The largest MP particle recorded was in the 200 μm size class. The concentrations of fibers were not reported, as fiber detection by FTIR imaging was not available at the time of analyses. Two- and three-dimensional simulations of particle transport trajectories suggest different pathways for certain polymer types. A positive correlation between MP size composition and particulate organic carbon indicates interactions with biological processes in the water column.

Combined Use of Scanning Electron Microscopy-Energy-Dispersive X-ray Spectroscopy and Fourier Transform Infrared Imaging Coupled with Principal Component Analysis in the Study of Ancient Egyptian Papyri.

This paper reports the results of a spectroscopic study on the chemistry of some small papyrus fragments arising from three Egyptian excavation sites. The aim of this investigation was to verify the possibility to identify significant differences in ancient Egyptian papyri using noninvasive analytical methods, that is, ATR (attenuated total reflection)–FTIR (Fourier transform infrared) spectroscopic imaging and scanning electron microscopy–energy-dispersive X-ray spectroscopy. Differences in both lignin and cellulose compositions, which are difficult to detect with traditional FTIR and FTIR imaging spectral analysis, were revealed by the multivariate approach, and the second derivative spectroscopy was applied to enhance the spectrum resolution. Thus, it has been possible to recognize a fragment characterized by the presence of lead and of long chain aliphatic organic compound, which are not present in the other fragments, in the ink region. These data show not only that the combination of these techniques can provide important chemical information, such as to evidence the different compositions and manufacture of each papyrus, but also that metal inks were probably used also in ancient Egyptian papyri.