Two-dimensional correlation and codistribution spectroscopy (2DCOS and 2DCDS) analyses of time-dependent ATR IR spectra of d-glucose anomers undergoing mutarotation process in water

Unveiling the crucial role of iron oxide transformation in simultaneous immobilization of nanoplastics and organic matter

Nanoplastics (NPs) have been found in natural environments. However, the sequestration of NPs and natural organic matter (NOM) coupled with the Fe(III) hydrolysis and subsequent iron oxides transformation remains unclear. Here, we investigated the behaviors of NPs during the dynamic transformation process of iron oxides in the presence of humic acids (HA). The quantification results of europium chelate-labeled polystyrene (PS) NPs and HA indicate that 87.60 % of NPs and 49.45 % of HA were sequestered in the precipitate by the end of the transformation (240 h). High-angle annular dark-field-scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (HAADF-STEM-EDS) images show that NPs were doped into iron oxides during the recrystallization of ferrihydrite aggregates, while HA were adsorbed or penetrated into the nanoscale pores on the mineral surfaces, suggesting the formation of a stable iron oxides-NPs-NOM ternary nanocomplex with a core-shell structure. Fourier transform infrared spectrometer (FTIR) and two-dimensional correlation spectroscopy (2D-COS) analysis indicate that functional groups of iron oxides and HA, including hydroxyl, carboxyl, and FeO bonds, played a role in the binding process. In the presence of HA, the stability of the coprecipitation system was enhanced due to the increased electrostatic repulsion, which facilitated the full incorporation of NPs with iron oxides. These findings provide a new insight into the simultaneous immobilization of NPs and NOM.

Ammonia nitrogen affects bacterial virulence and conditional pathogenic bacterial growth by regulating biofilm microbial metabolism and EPS secretion in laboratory scale distribution systems

The control of conditional pathogenic bacteria and inhibition of their virulence factors (VFs) in drinking water distribution systems (DWDSs) is vital for drinking water safety. This study adopted two groups of DWDSs to investigate how ammonia nitrogen affects bacterial VFs and conditional pathogenic bacterial growth in biofilms. Our results indicated that Acidimicrobium (95,916.62 ± 119.24 TPM), Limnohabitans (30,338.81 ± 139.14 TPM), and Sediminibacterium (10,658.01 ± 48.94 TPM) were predominant in the biofilm bacterial community of DWDSs with NH3-N addition. Under these conditions, the abundances of various bacterial metabolites, such as L-glutamate (1.45-fold), 2-oxoglutarate (1.24-fold), pyruvate (2.10-fold), and adenosine monophosphate (AMP, 5.29-fold), were significantly upregulated, which suggested the upregulation of amino acid, carbohydrate, nucleotide, lipid, pyrimidine and purine metabolism. These metabolic pathways accelerated extracellular polymeric substance (EPS) secretion. The protein concentration in EPS also increased to 187.59 ± 0.58 μg/cm2. The increased EPS secretion promoted the amide I CO group of the EPS protein to interact with the surface of the DWDSs, thus enhancing the ability of bacteria (especially conditional pathogenic bacteria) to adhere to the pipe surface to form biofilms. Due to EPS protection, the abundance of the adherence subtype of VFs and the plate counts of Pseudomonas aeruginosa increased to 5912.8 ± 21.89 TPM and 655.78 ± 27.10 CFU/cm2, respectively. Therefore, NH3-N in DWDSs increased bacterial VFs levels and promoted the growth of some conditional pathogenic bacteria by regulating biofilm microbial metabolic pathways and EPS secretion, ultimately impacting the interaction between EPS and the pipe surface.

Aged Lignocellulose Fibers of Cedar Wood (9th and 12th Century): Structural Investigation Using FTIR-Deconvolution Spectroscopy, X-Ray Diffraction (XRD), Crystallinity Indices, and Morphological SEM Analyses

The characterization of lignocellulosic biomass present in archaeological wood is crucial for understanding the degradation processes affecting wooden artifacts. The lignocellulosic fractions in both the external and internal parts of Moroccan archaeological cedar wood (9th, 12th, and 21st centuries) were characterized using infrared spectroscopy (FTIR-ATR deconvolution mode), X-ray diffraction (XRD), and SEM analysis. The XRD demonstrates a significant reduction in the crystallinity index of cellulose from recent to aging samples. This finding is corroborated by the FTIR analysis, which shows a significant reduction in the area profiles of the C-H crystalline cellulosic bands (1374, 1315, and 1265 cm-1) and C-O-C (1150-1000 cm-1). The alterations in the lignin fraction of aging samples (from the 9th and 12th centuries) were demonstrated by a reduction in the intensity of the bands at 1271 and 1232 cm-1 (Car-O) and the formation of new compounds, such as quinones and/or diaryl carbonyl structures, within the 1700-1550 cm-1 range. The SEM images of cedar wood samples from the 9th and 12th centuries reveal voids, indicating that the entire cell wall component has been removed, a characteristic feature of simultaneous white rot fungi. In addition, horizontal "scratches" were noted, indicating possible bacterial activity.

Enhanced removal of microplastics from wastewater treatment plants by a novel magnetic filter

Microplastics (MPs) discharged from wastewater treatment plants (WWTPs) have emerged as serious pollutants in aquatic environments. Herein, a new magnetic filter (MFA) was prepared using an acidification-magnetization method with fly ash (FA) as the base material. The filter specifically targeted the removal of 1-μm polystyrene microspheres (PSMPs) because of the challenges they pose in filtration processes. The findings demonstrated that MFA filter exhibited superior PSMPs removal efficiency, with increases of 219%, 250%, and 288% compared to FA at flow rates of 1, 3, and 5 mL min-1, respectively. Scanning electron microscopy and other characterizations provided insights into the removal mechanisms of PSMPs using the MFA filter, which combined electrostatic attraction, π-electron conjugation, hydrogen bonding, and complexation. Environmental variables, such as solution pH, ionic strength, and dissolved organic matter, were identified as considerable influences in the removal process of PSMPs. The practical application confirmed that the MFA filter considerably promoted the elimination of MPs from the secondary treatment effluent of WWTPs without having any toxic effects on freshwater fish. Thus, this study provides a new approach to the resource utilization of FA, which would prominently promote its application prospects in MPs immobilization and removal from wastewater effluent.

Cooperation of rhamnolipid and thermophilic bacteria modifies proteinic structure, microbial community, and metabolic traits for efficient solubilization and acidogenesis of mariculture solid wastes

Anaerobic fermentation combined with thermophilic bacteria (TB) pretreatment is a promising method to realize effective waste management and carbon resource recovery. However, undesirable properties of high-strength mariculture solid wastes (MSW) such as high solids concentration, excessive salinity and poor bioavailability limited the overall solubilization and acidogenic efficiency. This study innovatively introduced rhamnolipid (RL) to alleviate this adverse effect, and unveiled its cooperation with TB on enhancing organic matter dissolution and volatile fatty acids (VFAs) production. The results showed that VFAs yield from pretreated MSW was improved by 9.4-15.1 folds with enriched acetate (81.4%-94.4%) in the TB+RL groups. The co-pretreatment of RL and TB disintegrated substrate structure for efficient release of electron shuttles and biodegradable organics. This was because introducing RL reconstructed solid-liquid interfacial charge and molecular arrangement, improved thermophilic enzyme activity, and reduced apoptosis and necrosis cells of TB. Substrate bioavailability was further improved with proteinic structure shifted from α-helix and β-sheet to random coil and aggregated strands, and amide II and carboxyl groups interacted with RL molecules. These changes induced the selective enrichment of hydrolytic and acidogenic bacteria, and the upregulated expression of encoding genes responsible for transmembrane transport, protein hydrolysis, carbohydrate metabolism and acetate biosynthesis. This study provides a new strategy to overcome the bottlenecks of acidogenesis from high-strengthen organic wastes and deciphers the underlying mechanism.

Nano-sized polystyrene and magnetite collectively promote biofilm stability and resistance due to enhanced oxidative stress response

Despite the growing prevalence of nanoplastics in drinking water distribution systems, the collective influence of nanoplastics and background nanoparticles on biofilm formation and microbial risks remains largely unexplored. Here, we demonstrate that nano-sized polystyrene modified with carboxyl groups (nPS) and background magnetite (nFe3O4) nanoparticles at environmentally relevant concentrations can collectively stimulate biofilm formation and prompt antibiotic resistance. Combined exposure of nPS and nFe3O4 by P. aeruginosa biofilm cells stimulated intracellular reactive oxidative species (ROS) production more significantly compared with individual exposure. The resultant upregulation of quorum sensing (QS) and c-di-GMP signaling pathways enhanced the biosynthesis of polysaccharides by 50 %- 66 % and increased biofilm biomass by 36 %- 40 % relative to unexposed control. Consistently, biofilm mechanical stability (measured as Young's modulus) increased by 7.2-9.1 folds, and chemical stress resistance (measured with chlorine disinfection) increased by 1.4-2.0 folds. For P. aeruginosa, the minimal inhibitory concentration of different antibiotics also increased by 1.1-2.5 folds after combined exposure. Moreover, at a microbial community-wide level, metagenomic analysis revealed that the combined exposure enhanced the multi-species biofilm's resistance to chlorine, enriched the opportunistic pathogenic bacteria, and promoted their virulence and antibiotic resistance. Overall, the enhanced formation of biofilms (that may harbor opportunistic pathogens) by nanoplastics and background nanoparticles is an overlooked phenomenon, which may jeopardize the microbial safety of drinking water distribution systems.

Adsorption characteristics and mechanisms of water-soluble polymers (PVP and PEG) on kaolin and montmorillonite minerals

The excessive use and accumulation of water-soluble polymers (WSPs, known as "liquid plastics") in the environment can pose potential risks to both ecosystems and human health, but the environmental fate of WSPs remains unclear. Here, the adsorption behavior of WSPs with different molecular weight on kaolinite (Kaol) and montmorillonite (Mt) were examined. The results showed that the adsorption of PEG and PVP on minerals were controlled by hydrogen bond and van der Waals force. The Fourier transform infrared (FTIR) spectra and two-dimensional correlation spectroscopy (2D-COS) analysis revealed that there were interactions between the Al-O and Si-O groups of the minerals and the polar O- or N-containing functional groups as well as the alkyl groups of PEG and PVP. The adsorption characteristics of WSPs were closely related to their molecular weight and the pore size of minerals. Due to the relatively large mesopore size of Kaol, both PEG and PVP were absorbed into inner spaces, for which the adsorption capacity increased with molecular weight of the polymers. For Mt, all types of PEG could enter its micropores, while PVP with larger molecular weights appeared to be confined externally, leading to a decrease in the adsorption capacity of PVP with increasing molecular weight. The findings of this study provide a theoretical basis for scientific evaluation of environmental processes of WSPs.

The interaction between extracellular polymeric substances and corrosion products in pipes shaped different bacterial communities and the effects of micropollutants

There are growing concerns over the effects of micropollutants on biofilms formation and antibiotic resistance gene (ARGs) transmission in drinking water distribution pipes. However, there was no reports about the influence of the interaction between extracellular polymeric substances (EPS) and corrosion products on biofilms formation. Our results indicated that the abundance of quorum sensing (QS)-related genes, polysaccharide and amino acids biosynthesis genes of EPS was 6747-8055 TPM, 2221-2619 TPM, and 1461-1535 TPM in biofilms of cast iron pipes, respectively, which were higher than that of stainless steel pipes. The two-dimensional correlation spectroscopy (2D-COS) analysis of attenuated total reflectance-Fourier transform infrared spectrometry (ATR-FTIR) results indicated that polysaccharide of EPS was more easily adsorbed onto the corrosion products of cast iron pipes. Therefore, more human pathogenic bacteria (HPB) carrying ARGs were formed in biofilms of cast iron pipes. The amide I and amide II components and phosphate moieties of EPS were more susceptible to the corrosion products of stainless steel pipes. Thus, more bacteria genera carrying mobile genetic elements (MGE)-ARG were formed in biofilms of stainless steel pipes due to more abundance of QS-related genes, amino acids biosynthesis genes of EPS and the functional genes related to lipid metabolism. The enrichment of dimethyl phthalate (DMP), perfluorooctanoic acid (PFOA) and sulfadiazine (SUL) in corrosion products induced upregulation of QS and EPS-related genes, which promoted bacteria carrying different ARGs growth in biofilms, inducing more microbial risks.

Structural changes of polysaccharides from Astragulus after honey processing and their bioactivities on human gut microbiota

BACKGROUND

Astragali Radix (also known as Astragulus) is a traditional medicinal and edible homologous plant for tonifying Qi. Honey-processed Astragalus is a dosage form of Astragali Radix processed with honey, which exhibited better efficacy of tonifying Qi than the raw product. Polysaccharides are their main active components.

RESULTS

APS2a and HAPS2a were initially isolated from Astragulus and honey-processed Astragulus. Both of them are highly branched acidic heteropolysaccharides containing ɑ-configuration and β-configuration glycosidic bonds. The molecular weight and the molecular dimension of HAPS2a decreased and the GalA contained in APS2a was converted to Gal in HAPS2a. The α-configuration galactose residue 1,3,4-α-Galp in the backbone of APS2a was converted to the corresponding β-configuration galactose residue 1,3,4-β-Galp in the backbone of HAPS2a and the uronic acid residue T-α-GalpA in the sidechain of APS2a was converted to the corresponding neutral residue T-α-Galp in the side chain of HAPS2a. Bioactivity results showed that HAPS2a had better probiotic effects on Bacteroides ovatus, Bacteroides thetaiotaomicron, Bifidobacterium longum and Lactobacillus rhamnosus strains than APS2a. After degradation, the molecular weights of HAPS2a and APS2a decreased with the changes in their monosaccharide composition. The contents of total short-chain fatty acids (SCFAs) and other organic acids in HAPS2a group were higher than APS2a group.

CONCLUSIONS

Two novel high-molecular-weight polysaccharides named APS2a and HAPS2a had different probiotic activities in vitro, which might be due to their structural differences before and after honey processing. Both of them might be possibly used as an immunopotentiator in healthy foods or dietary supplement. © 2023 Society of Chemical Industry.

Building deep learning and traditional chemometric models based on Fourier transform mid-infrared spectroscopy: Identification of wild and cultivated Gastrodia elata

To identify wild and cultivated Gastrodia elata quickly and accurately, this study is the first to apply three-dimensional correlation spectroscopy (3DCOS) images combined with deep learning models to the identification of G. elata. The spectral data used for model building do not require any preprocessing, and the spectral data are converted into three-dimensional spectral images for model building. For large sample studies, the time cost is minimized. In addition, a partial least squares discriminant analysis (PLS-DA) model and a support vector machine (SVM) model are built for comparison with the deep learning model. The overall effect of the deep learning model is significantly better than that of the traditional chemometric models. The results show that the model achieves 100% accuracy in the training set, test set, and external validation set of the model built after 46 iterations without preprocessing the original spectral data. The sensitivity, specificity, and the effectiveness of the model are all 1. The results concluded that the deep learning model is more effective than the traditional chemometric model and has greater potential for application in the identification of wild and cultivated G. elata.

A new effective method for identifying boletes species based on FT-MIR and three dimensional correlation spectroscopy projected image processing

This study proposed the necessity of identifying the species for boletes in combination with the medicinal value, nutritional value and the problems existing in the industrial development of boletes. Based on the preprocessing of Fourier transform mid-infrared spectroscopy (FT-MIR) by 1st, 2nd, SNV, 2nd + MSC and 2nd + SG, Multilayer Perceptron (MLP) and CatBoost models were established. To avoid complex preprocessing and feature extraction, we try deep learning modeling methods based on image processing. In this paper, the concept of three-dimensional correlation spectroscopy (3DCOS) projection image was proposed, and 9 datasets of synchronous, asynchronous and integrative images are generated by computer method. In addition, 18 deep learning models were established for 9 image datasets with different sizes. The results showed that the accuracy of the three types of synchronous spectral models reached 100%, while the accuracy of the asynchronous spectral and integrative spectral models of 3DCOS projection images were 96.97% and 97.98% in the case of big datasets, which overcame the defects of poor modeling effect of asynchronous spectral and integrative spectral in previous two-dimensional correlation spectroscopy (2DCOS) studies. In conclusion, the modeling results of 3DCOS projection images are perfect, and we can apply this method to other identification fields in the future.

Water structure modification by d-(+)-glucose at different concentrations and temperatures-effect of mutarotation

Water structure modification by carbohydrates is essential both in chemistry and life processes and in particular, molecular level interaction of glucose with water is very important. With a view to developing a fundamental knowledge base, thermodynamic parameters derived from measurements of density, viscosity, and refractive index have been analyzed to investigate how d-(+)-glucose alters the structure of water at various concentrations and temperatures. The nature and extent of the interactions have been investigated using apparent molar volume, Jones-Dole constants, changes in free energy (ΔG), changes in entropy (ΔS), and changes in enthalpy (ΔH) for viscous flow. Using measurements from dynamic light scattering (DLS), the sizes of the aggregates were studied. The kinetics of mutarotation have been investigated using polarimetry and the structural effect on water during mutarotation between α-d-glucose and β-d-glucose with time has been explored by near-infrared (NIR) spectroscopy. The spectroscopic results were examined using difference spectroscopy and two-dimensional correlation spectroscopy (2DCOS). The absorption bands of water shift to a higher wavenumber irrespective of the concentration of the solution with time due to the enhancement of the cleavage of hydrogen bonding in water. At high temperatures, three bands in the region 7100-7350 cm^-1 are attributed to the first overtones of the hydrogen-bonded -O-H stretching vibration. Refractive index values indicate an increase in the density of the anomer solutions with time, suggesting an increase in free water concentration. These results provide evidence for more than one water molecule being involved in the mechanism of mutarotation and propose a concerted mechanism for proton transfer.

Machine learning and deep learning based on the small FT-MIR dataset for fine-grained sampling site recognition of Boletus tomentipes

This study proposed the necessity of identifying the sampling sites for Boletus tomentipes (B.tomentipes) in combination with cadmium content and environmental factors. Based on fourier transform mid-infrared spectroscopy (FT-MIR) preprocessing by 1st, 2nd, MSC, SNV and SG, five machine learning (ML) algorithms (NB, DT, KNN, RF, SVM) and three Gradient Boosting Machine (GBM) algorithms (XGBoost, LightGBM, CatBoost) were built. To avoid complex preprocessing, we construct BoletusResnet model, propose the concepts of 3DCOS, 3DCOS projected images, index images in addition to 2DCOS, and combine them with deep learning (DL) for classification for the first time. It shows that GBM has higher accuracy than ML and DL has better accuracy than GBM. The four DL models presented in this paper achieve fine-grained sampling sites recognition based on small samples with 100 % accuracy, and a computer application system was developed on them. Therefore, spectral image processing combined with DL is a rapid and efficient classification method which can be widely used in food identification.

Toxic effects of pristine and aged polystyrene and their leachate on marine microalgae Skeletonema costatum

The acute toxic effects of pristine and aged polystyrene (P-PS and A-PS) and their leaching solutions (L-PS) on microalgae Skeletonema costatum were investigated by measuring algal density and growth inhibition rate (IR), chlorophyll concentration and photosynthetic efficiency (Fv/Fm) over 96 h. Total protein (TP), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) were measured to analyze the oxidative damage to microalgae by microplastics and their leachates. Hydrodynamic diameter of microplastics in seawater, FITR and SEM images were used to study the changes of polystyrene during aging. The interaction of algae cell with microplastics and the cellular ultrastructure changes of cells were analyzed combined with electron microscopy for a comprehensive and systematic understanding on the mechanisms of microplastic toxicity to microalgae. Both high concentration and small size of PS had significant inhibitory effect on the growth of microalgae, and the inhibitory effect was greater with increasing exposure time. The inhibition effect of aged microplastics was more obvious, which was speculated to be caused by the synergistic effect of aged PS itself and leaching solution. The negative effect of leaching solution on microalgae was due to the release of some additives during the aging process. The content of MDA reached the highest value of 54.41 nmol/mgprot in 1.0 μm 50 mg/L A-PS treatment group, and A-PS were found to be more prone to heterogeneous aggregation with algae cells by SEM.

Exposed facets mediated interaction of polystyrene nanoplastics (PSNPs) with iron oxides nanocrystal

Nanoplastics (NPs), which are often detected in the natural environment, are regarded as a group of emerging pollutants. Hematite is a substance that exists widely in the surface environment and has an important impact on the environmental behavior of pollutants. Clarifying the migration of NPs requires an in-depth understanding of intrinsic interaction mechanisms of NPs with iron-containing minerals. The interaction process of polystyrene nanoplastics (PSNPs) on the hematite exposed facets was systematically studied by experiments under different conditions, adsorption isotherm curves, Fourier Transform infrared (FTIR) spectroscopy and two-dimensional correlation spectroscopy (2D-COS) analyses. We found that PSNPs were adsorbed on the three exposed faces of hematite ({001}, {012}, and {100}) by electrostatic interaction, respectively, but the capacities for PSNPs were different. Adsorption models were established to explore the preferred interaction surface dependent on the exposed facets, and it was found that {012} surfaces were more favorable for PSNPs adsorption, while {001} surface has better adsorption capacity for PSNPs than {100} surface, which is due to the different density and proportion of hydroxyl groups on the exposed facets of hematite. These findings elucidated the dependence of PSNPs adsorption on the hematite facets, and illustrated t the effect of hematite on the migration of PSNPs in the environment.

Aging significantly increases the interaction between polystyrene nanoplastic and minerals

With the massive use and discarding of plastic products, plastic particles, including nanoplastics (NPs), which are continuously released under the action of environmental factors, are posing greater risk to the ecosystem and human health. NPs exposed to the environment experience aging, which can significantly change their physical and chemical properties and affect their environmental behavior. Here, we examined the adsorption behavior of polystyrene nanoplastic (PSNP) aging by ultraviolet (UV) exposure on different minerals (goethite, magnetite, kaolinite and montmorillonite). Aging not only changes the surface morphology of PSNP, but also increases the surface negative charge and produces a large number of oxygen-containing functional groups (OFGs). Incubation of aged PSNP with minerals indicated that iron oxides (goethite and magnetite) showed stronger interactions with aged PSNP than pristine PSNP, and there was an interaction between clay minerals and aged PSNP. The adsorption experiments and scanning electron microscopy (SEM) suggested that the higher adsorption capacity of a mineral surface to aged PSNP may be related to electrostatic attraction and ligand exchange. The Fourier transform infrared (FTIR) spectra after adsorption showed that the adsorption affinity between the functional groups was different, and two-dimensional correlation spectroscopy (2D-COS) analysis further indicated that the mineral preferentially adsorbed the aged PSNP in accordance with the order of OFGs. The findings provide a theoretical basis for scientific evaluation of ecological risks of NPs in the environment.

Differentiation of ethanol-water clusters in Fenjiu by two-dimensional correlation fluorescence and Raman spectra

The taste of different flavor liquor is multifarious, but the same brand liquor with different quality is truth. The essence of supramolecular ethanol-water clusters and their intrinsic structural differences in three kinds of Fenjiu are studied by two-dimensional correlation spectra (2D-COS) of fluorescence and Raman. The 2D-COS of fluorescence reveals the prominent emission peaks of three Fenjiu are apparently different. The central fluorescence peak of Fenjiu (a) is located at 330 nm, corresponding to the cluster of (H₂O)_m(EtOH)_n. In Fenjiu (b), the emission peak appears near 310 nm, while those of Fenjiu (c) appear mainly near 310 and 373 nm, corresponding to the clusters of (H₂O)(EtOH)_n and (H₂O)_m(EtOH), respectively. Based on 2D-COS of Raman, the peak of Fenjiu (b) at 3440 cm^-1 changes initially, indicating its disorder degree is getting higher with continuous dilution with water. However, along with the dilution of Fenjiu (a) and Fenjiu (c), the peak located near 3200 cm^-1 changes in priority, indicating that the degree of association between ethanol and water is high, and the clusters formed there are stable. Therefore, this work provides the combined methods to distinguish different supramolecular sets in Fenjiu, applying liquor differentiation in the future.

The Storage Period Discrimination of Bolete Mushrooms Based on Deep Learning Methods Combined With Two-Dimensional Correlation Spectroscopy and Integrative Two-Dimensional Correlation Spectroscopy

Boletes are favored by consumers because of their delicious taste and high nutritional value. However, as the storage period increases, their fruiting bodies will grow microorganisms and produce substances harmful to the human body. Therefore, we need to identify the storage period of boletes to ensure their quality. In this article, two-dimensional correlation spectroscopy (2DCOS) images are directly used for deep learning modeling, and the complex spectral data analysis process is transformed into a simple digital image processing problem. We collected 2,018 samples of boletes. After laboratory cleaning, drying, grinding, and tablet compression, their Fourier transform mid-infrared (FT-MIR) spectroscopy data were obtained. Then, we acquired 18,162 spectral images belonging to nine datasets which are synchronous 2DCOS, asynchronous 2DCOS, and integrative 2DCOS (i2DCOS) spectra of 1,750–400, 1,450–1,000, and 1,150–1,000 cm^–1 bands. For these data sets, we established nine deep residual convolutional neural network (ResNet) models to identify the storage period of boletes. The result shows that the accuracy with the train set, test set, and external validation set of the synchronous 2DCOS model on the 1,750–400-cm^–1 band is 100%, and the loss value is close to zero, so this model is the best. The synchronous 2DCOS model on the 1,150–1,000-cm^–1 band comes next, and these two models have high accuracy and generalization ability which can be used to identify the storage period of boletes. The results have certain practical application value and provide a scientific basis for the quality control and market management of bolete mushrooms. In conclusion, our method is novel and extends the application of deep learning in the food field. At the same time, it can be applied to other fields such as agriculture and herbal medicine.

Tracking the Micro-Heterogeneity and Hydrogen-Bonding Interactions in Hydroxyl-Functionalized Ionic Liquid Solutions: A Combined Experimental and Computational Study

Ionic liquids (ILs) are an important class of media that are usually used in combination with polar solvents to reduce costs and tune their physicochemical properties. In this regard, it is essential to understand the influence of adding solvents on the properties of ILs. In this work, the micro-heterogeneity and H-bonding interactions between a hydroxyl-functionalized IL, [HOEmim][TFSI], and acetonitrile (ACN) were investigated by attenuated total reflection Fourier transform infrared spectroscopy and molecular simulations. All studied IL-ACN mixtures were found to deviate from the ideal mixtures. The degree of deviations reaches the maximum at about x(ACN)=0.7 with the presence of both homogeneous clusters of pure IL/ACN and heterogeneous clusters of IL-ACN. With the addition of ACN to IL, the mixtures undergo the transformation from "ACN solvated in [HOEmim][TFSI]" to "[HOEmim][TFSI] solvated in ACN". It is found that the newly formed H-bonding interactions between the IL and ACN is the main factor that contributes to the red shifts of O-H, C₂ -H, C_4,5 -H, and C_alkyl -H of [HOEmim]⁺ cation, and the blue shifts of C-D, C≡N of ACN, and C-F, S=O of [TFSI]^- anion. These in-depth studies on the mixtures of hydroxyl-functionalized IL and acetonitrile would help to understand the micro-heterogeneity and H-bonding interactions of miscible solutions and shed light on exploring their applications.

Temperature-Dependent Dynamical Evolution in Coum/SBE-β-CD Inclusion Complexes Revealed by Two-Dimensional FTIR Correlation Spectroscopy (2D-COS)

A combination of Fourier transform infrared spectroscopy in attenuated total reflectance geometry (FTIR-ATR) and 2D correlation analysis (2D-COS) was applied here for the first time in order to investigate the temperature-dependent dynamical evolution occurring in a particular type of inclusion complex, based on sulfobutylether-β-cyclodextrin (SBE-β-CD) as hosting agent and Coumestrol (7,12-dihydorxcoumestane, Coum), a poorly-soluble active compound known for its anti-viral and anti-oxidant activity. For this purpose, synchronous and asynchronous 2D spectra were calculated in three different wavenumber regions (960-1320 cm^-1, 1580-1760 cm^-1 and 2780-3750 cm^-1) and over a temperature range between 250 K and 340 K. The resolution enhancement provided by the 2D-COS offers the possibility to extract the sequential order of events tracked by specific functional groups of the system, and allows, at the same time, the overcoming of some of the limits associated with conventional 1D FTIR-ATR analysis. Acquired information could be used, in principle, for the definition of an optimized procedure capable to provide high-performance T-sensitive drug carrier systems for different applications.

2D Correlation Spectroscopy (2DCoS) Analysis of Temperature-Dependent FTIR-ATR Spectra in Branched Polyethyleneimine/TEMPO-Oxidized Cellulose Nano-Fiber Xerogels

Fourier transform infrared spectroscopy in attenuated total reflectance geometry (FTIR-ATR), combined with a 2D correlation analysis, was here employed to investigate temperature-induced spectral changes occurring in a particular type of novel cellulosic-based nano-material prepared using 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) oxidized and ultra-sonicated cellulose nano-fibers (TOUS-CNFs) as three-dimensional scaffolds, and branched polyethyleneimine (bPEI) as cross-linking agent. The aim was to highlight the complex sequential events involving the different functional groups of the polymeric network, as well as to gain insight into the interplay between the amount of bPEI and the resulting sponge-like material, upon increasing temperature. In this framework, synchronous and asynchronous 2D spectra were computed and analyzed in three wavenumber regions (900-1200 cm-1, 1500-1700 cm-1 and 2680-3780 cm-1), where specific vibrational modes of the cellulosic structure fall, and over a T-range between 250 K and 340 K. A step-by-step evolution of the different arrangements of the polymer functional groups was proposed, with particular regard to how the cooperativity degree of inter- and intramolecular hydrogen bonds (HBs) changes upon heating. Information acquired can be useful, in principle, in order to develop a next-generation, T-sensitive novel material to be used for water remediation applications or for drug-delivery nano-vectors.

Charge mediated interaction of polystyrene nanoplastic (PSNP) with minerals in aqueous phase

A large number of plastic products potentially become smaller particles, including nanoplastics, under multiple actions in the environment. The interactions between nanoplastic particles and constituents in the environment, such as minerals, would greatly affect the transport, fate and toxic effects of nanoplastics. In this study, the interactions of polystyrene nanoplastic (PSNP) with four typical minerals, including goethite, magnetite, kaolinite and montmorillonite, in aqueous phase were investigated. The stability of PSNP colloidal suspension decreased in the presence of the positively charged goethite or magnetite, while it was not affected by the negatively charged montmorillonite and kaolinite, suggesting that there was a strong electrostatic attraction between PSNP and the two iron oxides. Incubation of PSNP with other three metal oxides with different surface charges, MnO₂, Al₂O₃ and SiO₂, confirmed the importance of electrostatic interaction in the stability of PSNP suspension. The transmission electron microscopy (TEM) analysis and batch adsorption experiments indicated that PSNP was effectively adsorbed on goethite or magnetite due to the strong electrostatic attraction between them. The Fourier transform infrared spectra (FTIR) and two-dimensional correlation spectroscopy (2D-COS) analyses indicated that there was strong hydrogen bonding between the -OH (γ-FeOOH) of goethite and PSNP, contributing to the higher adsorption of PSNP on goethite than magnetite. These findings shed light on the interactions of PSNP with mineral surfaces, and potential fate of PSNP under natural conditions in the water environment.

Biomolecular and bioanalytical applications of infrared spectroscopy - A review

Infrared (IR; or mid-infrared, MIR; 4000-400 cm^-1; 2500-25,000 nm) spectroscopy has become one of the most powerful and versatile tools at the disposal of modern bioscience. Because of its high molecular specificity, applicability to wide variety of samples, rapid measurement and non-invasivity, IR spectroscopy forms a potent approach to elucidate qualitative and quantitative information from various kinds of biological material. For these reasons, it became an established bioanalytical technique with diverse applications. This work aims to be a comprehensive and critical review of the recent accomplishments in the field of biomolecular and bioanalytical IR spectroscopy. That progress is presented on a wider background, with fundamental characteristics, the basic principles of the technique outlined, and its scientific capability directly compared with other methods being used in similar fields (e.g. near-infrared, Raman, fluorescence). The article aims to present a complete examination of the topic, as it touches the background phenomena, instrumentation, spectra processing and data analytical methods, spectra interpretation and related information. To suit this goal, the article includes a tutorial information essential to obtain a thorough perspective of bio-related applications of the reviewed methodologies. The importance of the fundamental factors to the final performance and applicability of IR spectroscopy in various areas of bioscience is explained. This information is interpreted in critical way, with aim to gain deep understanding why IR spectroscopy finds extraordinarily intensive use in this remarkably diverse and dynamic field of research and utility. The major focus is placed on the diversity of the applications in which IR biospectroscopy has been established so far and those onto which it is expanding nowadays. This includes qualitative and quantitative analytical spectroscopy, spectral imaging, medical diagnosis, monitoring of biophysical processes, and studies of physicochemical properties and dynamics of biomolecules. The application potential of IR spectroscopy in light of the current accomplishments and the future prospects is critically evaluated and its significance in the progress of bioscience is comprehensively presented.