Amyloid refers to insoluble protein aggregates that are responsible for amyloid diseases but are also implicated in important physiological functions (functional amyloids). The widespread presence of ...protein aggregates but also, in most of the cases, their deleterious effects explain worldwide efforts made to understand their formation, structure and biological functions. We emphasized the role of FTIR and especially ATR-FTIR techniques in amyloid protein and/or peptide studies. The multiple advantages provided by ATR-FTIR allow an almost continuous structural view of protein/peptide conversion during the aggregation process. Moreover, it is now well-established that infrared can differentiate oligomers from fibrils simply on their spectral features. ATR-FTIR is certainly the fastest and easiest method to obtain this information. ATR-FTIR occupies a key position in the analysis and comprehension of the complex aggregation mechanism(s) at the oligomer and/or fibril level. These mechanism(s) seem to present strong similarities between different amyloid proteins and might therefore be extremely important to understand for both disease-associated and functional amyloid proteins. This article is part of a Special Issue entitled: FTIR in membrane proteins and peptide studies.
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•Structural features of amyloid fibrils highlighted by ATR-FTIR spectroscopy: a brief survey•Conformational changes promoting fibrils formation•Antiparallel β-sheet is the spectral feature of oligomers.•Is the antiparallel β-sheet structure a signature of amyloid cytotoxicity?•Organization of β-strands and β-sheet formation during aggregation
Microplastics are widespread contaminants, virtually present in all environmental compartments. However, knowledge on sources, fate and environmental concentration over time and space still is ...limited due to the laborious and varied analytical procedures currently used. In this work we critically review the methods currently used for sampling and detection of microplastics, identifying flaws in study design and suggesting promising alternatives. This work provides insights on bulk sample collection, separation, digestion, identification and quantification, and mitigation of cross-contamination. The sampling of microplastics will improve in representativeness and reproducibility through the determination of bulk sample volume, filter's pore size, density separation and digestion solutions, but also through use of novel methods, such as the enhancement of visual identification by staining dyes, and the generalized use of chemical characterization.
•Methods of sampling and detection of microplastics vary between groups.•Sampling and separation of microplastics needs to be standardized.•Removal of organic matter through digestion improves identification.•Visual inspection can be improved, chemical identification is essential.•Mitigation of cross-contaminations is required to validate the results.
: Various pharmaceutical preparations are widely used for clinical treatment. Elucidation of the mechanisms of drug release and evaluation of drug efficacy in biological samples are important in drug ...design and drug quality control.
: This review classifies recent applications of Fourier transform infrared (FTIR) spectroscopy in the field of medicine to comprehend drug release and diffusion. Drug release is affected by many factors of preparations, such as drug delivery system and microstructure polymorphism. The applications of FTIR imaging and nano-FTIR technique in biological samples lay a foundation for studying drug mechanism in vivo.
: FTIR spectroscopy meets the research needs on preparations to understand the processes and mechanisms underlying drug release. The combination of attenuated total reflectance-FTIR imaging and nano-FTIR accompanied by chemometrics is a potent tool to overcome the deficiency of conventional infrared detection. FTIR shows an enormous potential in drug characterization, drug quality control, and bio-sample detection.
•First study on kinetic behaviors and evolved gaseous products for SMS combustion.•Four iso-conversional models were adopted to calculate thermodynamic parameters.•Peak of CO2 and NO2 emissions ...occurred at the stage of fixed carbon combustion.•SO2 was released at devolatilization stage with a peak value of 334.21 °C.
The present study systematically investigated the combustion characteristics of spent mushroom substrate (SMS) using TG-MS (thermogravimetric/mass spectrometry) and TG-FTIR (thermogravimetric/Fourier transform infrared spectrometry) under five heating rates. The physicochemical characteristics and combustion index pointed to SMS as a promising biofuel for power generation. The high correlation coefficient of the fitting plots and similar activation energy calculated by various methods indicated that four suitable iso-conversional methods were used. The activation energy varied from 130.06 to 192.95 kJ/mol with a mean value of 171.49 kJ/mol using Flynn–Wall–Ozawa and decreased with the increased conversion degree. The most common emissions peaked at the range of 200–400 °C corresponding to volatile combustion stage, except for CO2, NO2 and NO. The peak CO2 emission occurred at 439.11 °C mainly due to the combustion of fixed carbon.
To investigate the effect of low moisture extrusion cooking on the structural changes of protein and expansion properties, a pea protein isolate was processed in a twin screw extruder at varying ...screw speed (400-700 min−1), moisture content (26–35%) and barrel temperature (130–170 °C). An expanded protein isolate matrix was achieved for a specific mechanical energy input above 180 kJ/kg and product temperatures above 130 °C. The expanded protein network was presumably stabilized by increased protein aggregation, which most likely was formed by α-helices, β-sheet, non-covalently bonded β-turn or anti-parallel β-sheet structures as identified by FTIR. SDS-PAGE suggested, that neither the vicilin nor the convicilin fraction of the protein were altered, whereas legumin was either proteolysed or aggregated. Processing reduced the protein’s water solubility. This knowledge contributes to a deeper understanding of the structural changes in a pea protein isolate as caused by low moisture extrusion.
•A direct expanded pea protein isolate (>80% protein) was achieved.•Expansion of pea protein isolate is shear and temperature dependant.•Expanded network was stabilized by β-sheet structures and protein aggregates.•Legumin was either proteolysed or aggregated, vicilin and convicilin were unaffected.•Protein solubility was reduced.
The occurrence of microplastic particles were evaluated on beaches along the Indian coast from three different locations Girgaon Mumbai (Arabian sea coast), Tuticorin, and Dhanushkodi (Bay of Bengal ...coast). Density separation method was adopted for isolation of microplastics from sand. Isolated microplastics were characterized using three different analytical techniques e.g. fluorescence microscopy (after staining with Nile Red), FTIR and SEM-EDS techniques. Microplastic concentrations in beach sands were from 45 ± 12 # MP kg−1 to 220 ± 50 # MP kg−1 of dry sand. The order of abundance of plastic type was polyethylene (43%) > polyethylene terephthalate (17.3%) ≈ polystyrene (17%) > polypropylene (12.3%) > Others (11%) > polyvinylchloride (1.33%), and very similar profile was observed for all monitored locations. SEM images show microplastics surfaces with characteristic cracks, suggests their polymer aging, mechanical and oxidative weathering, which was found highest for the microplastics collected from Mumbai.
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•The order of total microplastic abundance in beach sands was megacity, industrial city followed by religious and tourist city•Fibrous shapes microplastics were observed with the majority compared to granule shape, films.•Polyethylene and polystyrene microplastics were found in dominantly in beach sand samples.•SEM images of microplastics surfaces indicates their aging, mechanical and oxidative weathering.
FTIR spectroscopy is well known for its molecule fingerprinting capability but is also able to differentiate classes in complex biological systems. This includes strain typing and species level ...identification of bacterial, yeast or fungal cells, as well as distinguishing between cell layers in eukaryotic tissues. However, its use for the identification of macromolecules such as proteins remains underexplored and rarely used in practice. Here we demonstrate the efficacy of FTIR microspectroscopy coupled with machine learning methods for rapid and accurate identification of proteins in their dry state within minutes, from very small quantities of material, if they are obtained in a pure aqueous solution. FTIR microspectroscopy can provide additional information beside identification: it can detect small differences among different purification batches potentially originating from post-translational modifications or distinct folding states. Moreover, it distinguishes glycoproteins and evaluate glycosylation while detecting contaminants. This methodology presents itself as a valuable quality control tool in protein purification processes or any process requiring the utilization of precisely identified, pure proteins.
•FTIR microspectroscopy can be used to identify pure proteins in dried films with high classification accuracy and specificity.•The method is straightforward, swift and provide identification within minutes, employing nanograms of proteins.•The method is conformation sensitive, can identify glycoproteins, and can detect and identify contaminants.•The method works better for water soluble proteins, insoluble proteins can be difficult, but not impossible, to measure.
Microplastic pollution within the marine environment is of pressing concern globally. Accordingly, spatial monitoring of microplastic concentrations, composition and size distribution may help to ...identify sources and entry pathways, and hence allow initiating focused mitigation. Spatial distribution patterns of microplastics were investigated in two compartments of the southern North Sea by collecting sublittoral sediment and surface water samples from 24 stations. Large microplastics (500−5000 μm) were detected visually and identified using attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. The remaining sample was digested enzymatically, concentrated onto filters and analyzed for small microplastics (11−500 μm) using Focal Plane Array (FPA) FTIR imaging. Microplastics were detected in all samples with concentrations ranging between 2.8 and 1188.8 particles kg−1 for sediments and 0.1–245.4 particles m−3 for surface waters. On average 98% of microplastics were <100 μm in sediments and 86% in surface waters. The most prevalent polymer types in both compartments were polypropylene, acrylates/polyurethane/varnish, and polyamide. However, polymer composition differed significantly between sediment and surface water samples as well as between the Frisian Islands and the English Channel sites. These results show that microplastics are not evenly distributed, in neither location nor size, which is illuminating regarding the development of monitoring protocols.
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•All 46 analyzed sediment and surface water samples contained microplastics.•Microplastic concentrations were higher in sediment than surface water samples.•Polymer composition differed significantly between surface waters and sediments.•Microplastics <500 μm were more abundant and divers in polymer type than large ones.•Particles smaller 100 μm dominated clearly in both environmental compartments.
Capsule: Microplastic concentrations and compositions differ significantly between environmental compartments. Geographic distribution patterns are revealed by a statistical approach. Microplastics <500 μm are more abundant and diverse than >500 μm ones, rendering the exclusive analysis of later ones insufficient for environmental risk assessment.
In this study, the co-pyrolysis kinetics of tobacco stalk and scrap tire were investigated via thermogravimetric analyzer, while Fourier transform infrared spectrometer was used for the analysis of ...gas-phase products transition. The pyrolysis of tobacco stalk could be divided into three stages: moisture removal, volatile removal, and slow decomposition of residues. And there was an additional stage of the decomposition of additives for scrap tire. The positive interaction between tobacco stalk and scrap tire occurred when their ratio is 2:8, at which both differential thermal gravity peak temperatures reached a minimum of 320.5 and 390.7 °C in their corresponding regions. The size of the tire particles (from 250 μm to 3 mm) appeared to have little effect on the differential thermal gravity peak temperature of the mixtures. From the results of the kinetic analysis, the synergistic effect at multiple mixing ratios made the energy required for the co-pyrolysis process significantly lower than that of the single pyrolysis. Under the mixed conditions, the formation of organic gases and CO2 was suppressed, the possible mechanism involved was discussed. The results obtained in this study can be used to understand the co-pyrolysis of tobacco stalk/scrap tire and provide a basis for further industrial applications.
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•It is the first time to investigate the kinetics of biomass and tire co-pyrolysis.•The synergistic effect lowered the energy input of the process.•Tobacco stalks suppressed the formation of organic gases during co-pyrolysis.•Scrap tires can interact with tobacco stalks and lower the CO2 production.
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