Fourier Transform Infrared Techniques Research Articles

Fourier Transform Infrared (FT-IR) Spectroscopy and Simple Algorithm Analysis for Rapid and Non-Destructive Assessment of Cotton Fiber Maturity and Crystallinity for Plant Mapping.

Information on boll distribution within a cotton plant is critical to evaluate the adaptation and response of cotton plants to environmental and biotic stress in cotton production. Cotton researchers have applied available conventional fiber measurements, such as the high volume instrument (HVI) and advanced fiber information system (AFIS), to map the location and the timing of boll development and distribution within plants and further to determine within-plant variability of cotton fiber properties. Both HVI and AFIS require numerous cotton bolls combined for the measurement. As an alternative approach, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy was proposed to measure fiber maturity (MIR) and crystallinity (CIIR) of a sample as little as 0.5 mg lint. Extending fiber maturity and crystallinity measurement into a single boll for node-by-node mapping, FT-IR method might be advantageous due to less sampling amount compared with HVI and AFIS methods. Results showed that FT-IR technique enabled the evaluation of fiber MIR and CIIR at a boll level, which resulted in average MIR and CIIR values highly correlated with HVI micronaire (MIC) and AFIS maturity ratio (M). Hence, FT-IR technique possesses a good potential for a rapid and non-destructive node-by-node mapping of cotton boll maturity and crystallinity distribution.

Quantitative or qualitative biomolecular changes in blood serum composition induced by childhood obesity: A Fourier transform infrared examination

Childhood obesity (CO) negatively affects one in three children and stands as the fourth most common risk factor of health and well-being. Clarifying the molecular and structural modifications that transpire during the development of obesity is crucial for understanding its progression and devising effective therapies. The study was indeed conducted as part of an ongoing CO treatment trial, where data were collected from children diagnosed with CO before the initiation of non-drug treatment interventions. Our primary aim was to analyze the biochemical changes associated with childhood obesity, specifically focusing on concentrations of lipids, lipoproteins, insulin, and glucose. By comparing these parameters between the CO group (n = 60) and a control group of healthy children (n = 43), we sought to elucidate the metabolic differences present in individuals with CO. Our biochemical analyses unveiled lower LDL (low-density lipoproteins) levels and higher HDL (high-density lipoproteins), cholesterol, triglycerides, insulin, and glucose levels in CO individuals compared to controls. To scrutinize these changes in more detail, we employed Fourier transform infrared (FTIR) spectroscopy on the serum samples. Our results indicated elevated levels of lipids and proteins in the serum of CO, compared to controls. Additionally, we noted structural changes in the vibrations of glucose, β-sheet, and lipids in CO group. The FTIR technique, coupled with principal component analysis (PCA), demonstrated a marked differentiation between CO and controls, particularly in the FTIR region corresponding to amide and lipids. The Pearson test revealed a stronger correlation between biochemical data and FTIR spectra than between 2nd derivative FTIR spectra. Overall, our study provides valuable insights into the molecular and structural changes occurring in CO.

Application of the FTIR technique as a non-invasive tool to discriminate Portuguese olive oils with Protected Designation of Origin.

Three Portuguese olive oils with PDO ('Azeite do Alentejo Interior', 'Azeites da Beira Interior' and 'Azeite de Trás-os-Montes') were studied considering their physicochemical quality, antioxidant capacity, oxidative stability, total phenols content, gustatory sensory sensations and Fourier transform infrared (FTIR) spectra. All oils fulfilled the legal thresholds of EVOOs and the PDO's specifications. Olive oils from 'Azeite da Beira Interior' and 'Azeite de Trás-os-Montes' showed greater total phenols contents and antioxidant capacities, while 'Azeites da Beira Interior' presented higher oxidative stabilities. Linear discriminant models were developed using FTIR spectra (transmittance and the 1st and 2nd derivatives), allowing the correct identification of the oils' PDO (100 % sensitivity and specificity, repeated K-fold-CV). This study also revealed that multiple linear regression models, based on FTIR transmittance data, could predict the sweet, bitter, and pungent intensities of the PDO oils (R2 ≥0.979±0.016; RMSE≤0.26±0.05, repeated K-fold-CV). This demonstrates the potential of using FTIR as a non-destructive technique for authenticating oils with PDO.

Identification of compounds and functional groups of n-hexane seed extracts of Citrullus lanatus and Elaeis guineensis using GC-MS and FT-IR

Citrullus lanatus and Elaeis guineensis are regarded as two of the most significant edible fruits in terms of nutrition and medicine. Utilizing FTIR and GC-MS spectroscopy, the current work aims at identifying bioactive compounds and functional groups present in n-hexane seed extracts of Citrullus lanatus and Elaeis guineensis. The GC-MS approach is used to screen and identify phytocompounds. Using a Buck Scientific M530 USA spectrophotometer, the FTIR technique was used to identify the functional groups. Twenty-five (25) and twenty-nine (29) bioactive compounds were identified in Citrullus lanatus and Elaeis guineensis respectively, by Gas Chromatographic-Mass Spectrometry (GC-MS). Linoelaidic acid (58.79%) was the most prevalent compound identified in Citrullus lanatus seed extract. Gamma-tocopherol has the most diverse pharmacological role. n-hexadecanoic acid (16.82%), dodecanoic acid (0.12%), 9, 12-octadecadienoic acid methyl ester (3.45%) and 9, 12-octadecadienoic acid (Z, Z) (0.91%) are some of the other bioactive compounds detected. The most prevalent phytocompound identified in Elaeis guineensis seed extract is dodecanoic acid (37.20%), whereas the most diverse pharmacological activity was found in n-hexadecanoic acid. N-decanoic acid (6.32%), 6-octadecenoic acid (11.95%), octanoic acid (5.27%) and tetradecanoic acid (17.59%) are some other bioactive compounds identified. Ether, ethene, primary amine, carboxylic acid, cyclic ester, nitrile, methylene, primary, secondary and tertiary alcohols were detected at various wavelengths in both seed extracts by Fourier transform infrared (FTIR) spectrophotometer. Both extracts contain phytocompounds with antioxidant, anti-inflammatory and antimicrobial properties that are useful in preventing and treating diseases.

The characterization of pyrolysis oil from plastic waste using FTIR and GC-MS techniques

This research aims to investigate the characterization of pyrolysis oil products derived from plastic waste using FTIR (Fourier Transform Infrared) and GC-MS (Gas Chromatography-Mass Spectrometry) techniques. Plastic waste samples were subjected to pyrolysis, and the resulting pyrolysis oils were analyzed using FTIR to identify the functional groups present in the oil product. Additionally, GC-MS analysis was performed to obtain detailed information about the composition of the pyrolysis oils. The FTIR spectra revealed the presence of various functional groups, indicating the complexity of the pyrolysis oil composition. The functional groups identified in the pyrolysis oil included methyl C-H stretch and C-C stretch. The GC-MS analysis provided insights into the specific compounds present in the pyrolysis oils. The results demonstrate the potential of pyrolysis as a method for converting plastic waste into valuable oil products. The characterization of these products using FTIR and GC-MS techniques provides valuable information for further optimization and utilization of pyrolysis oil derived from plastic waste.

Flame‐retardant epoxy resin with good smoke‐suppression endowed by chitosan–cobalt/phosphorus complex

AbstractChitosan‐based flame‐retardant CS–Co–DOPA (CCD) was synthesized by the neutralization reaction of 10‐hydroxy‐9,10‐dihydro‐9‐oxo‐10‐phosphaphenanthrene‐10‐oxide (DOPA) with chitosan‐cobalt complex and fully characterized by scanning electron microscopy (SEM), energy‐dispersive spectrometer, x‐ray diffraction, X‐ray photoelectron spectroscopy (XPS), optical emission spectrometer, and Fourier transform infrared (FTIR) characterizations. The epoxy resin (EP) modified with CCD exhibited good flame retardancy. With the addition of 5 wt% CCD, the EP/CCD achieved UL‐94 V‐1 rating and possessed limiting oxygen index (LOI) value of 30%. Cone calorimetry (CC) test demonstrated that EP/CCD resulted in a remarkable reduction of peak smoke production rate (pSPR) and total smoke production (TSP) by 63% and 40%, respectively, showing an outstanding smoke suppression. The char residue obtained from the CC test was further characterized using SEM, FTIR, Raman, and XPS techniques. The results revealed that CCD facilitated the formation of a dense and compact char layer on EP during combustion, thereby impeding gas and heat transfer. In addition, TG‐IR was employed to investigate the gas‐phase flame‐retardant effect of EP/CCD composites, which revealed that CCD promotes the release of water, CO2, and other incombustible gases, altering the decomposition path of EP.

Experimental investigation on mechanical performance of PVC foam‐based E‐glass isophthalic polyester composites

AbstractThe present research paper investigates the chemical, thermal, mechanical, thermo‐mechanical properties, and fractography of sandwich composites made from E‐glass‐reinforced isophthalic polyester with Poly Vinyl Chloride (PVC) foam as a core by hand. These composites are commonly used in marine applications and manufactured by hand lay‐up method. A comparison is made between the properties of the PVC foam polyester sandwich composite with E‐glass layers on both sides (SC1) and the PVC foam isophthalic polyester sandwich composite with double layers of E‐glass on both sides (SC2) in relation to single‐layer E‐glass. Fourier transform infrared (FTIR) spectroscopy is employed to analyze the chemical composition of the composites. Various mechanical properties, including impact strength, flexural strength (FS), fracture toughness, and tensile strength (TS), are evaluated for the fabricated composites. Thermo‐mechanical and thermal properties are examined using dynamic mechanical analysis and thermogravimetric analysis (TGA), respectively. The chemical analysis identifies the unsaturation sites of (CH2)n, carbonyl group CO of the ester group, and the stretching of CH and CH3. The mechanical properties of SC2 composites are observed to be superior to those of SC1 composites. TGA revealed that both SC1 and SC2 composites showcased comparable temperature‐dependent weight loss patterns. Nonetheless, the SC2 composite displayed elevated glass transition temperature values and superior damping properties, as indicated by its higher Tanδ values. Examination of the fractured surfaces using a scanning electron microscopy (SEM) micrograph reveals a honeycomb structure, matrix cracking, and fiber pullout.Highlights Examination of the chemical, thermal, mechanical, and thermo‐mechanical attributes of sandwich composites made from E‐glass‐reinforced isophthalic polyester with PVC foam as the core. Evaluation of the impact of E‐glass layering on the thickness of the composite skin. Analysis of interfacial properties through FTIR techniques. Assessment of mechanical properties like impact strength, FS, fracture toughness, and TS. Investigation of fracture surfaces using SEM.

An improved method for measuring epi-wafer thickness based on the infrared interference principle: Addressing interference quality and multiple interferences in double-layer structures

The precise measurement of the thickness of substrate and epitaxial layers in epi-wafers is essential in the semiconductor chip fabrication process. This study presents a new method for measuring the thickness of epi-wafers using Fourier Transform Infrared (FTIR) technology, which allows for precise, simultaneous, and fast measurement of both substrate and epitaxial layers. To address the low accuracy of traditional FTIR techniques, a novel VMD-LSP algorithm is introduced, capable of precisely extracting frequency components from the original spectral signal to calculate the precise thickness of the substrate and epitaxial layers. This study also introduces an adaptive spectral excision algorithm and a high-precision thickness extraction algorithm to handle variations in the infrared light absorption of different epi-wafer materials, leading to weakened interference signals, and the challenges that stem from the unique double-layer structure of the wafer. These algorithms efficiently reduce the impact of poor spectral quality and multiple interferences on measurement results, resulting in improved measurement accuracy and stability. During the experimental phase, we compared our results obtained by ellipsometry as truth to evaluate the accuracy and stability of our proposed method. The results show an 85% reduction in measurement error and a 65% improvement in stability compared to traditional methods. As a result, our method meets the need for fast and efficient epi-wafer thickness measurement in semiconductor chip manufacturing, providing a feasible and effective solution to the challenge of epi-wafer thickness measurement.

Aerosol properties derived from ground-based Fourier transform spectra within the COllaborative Carbon Column Observing Network

Abstract. Fourier transform infrared (FTIR) spectroscopy is particularly relevant for climate studies due to its ability to provide information on both fine absorption structures (i.e. trace gases) and broadband continuum signatures (i.e. aerosols or water continuum) across the entire infrared (IR) domain. In this context, this study assesses the capability of the portable and compact EM27/SUN spectrometer, used within the research infrastructure COCCON (COllaborative Carbon Column Observing Network), to retrieve spectral aerosol properties from low-resolution FTIR solar absorption spectra (0.5 cm−1). The study focuses on the retrieval of aerosol optical depth (AOD) and its spectral dependence in the 873–2314 nm spectral range from COCCON measurements at the subtropical high-mountain Izaña Observatory (IZO, Tenerife, Spain), which were coincidentally carried out with standard sun photometry within the Aerosol Robotic Network (AERONET) in the 3-year period from December 2019 to September 2022. The co-located AERONET–COCCON database was used to cross-validate these two independent techniques in the common spectral range (870–1640 nm), demonstrating an excellent agreement at the near-coincident spectral bands (mean AOD differences limited to 0.005, standard deviations up to 0.021 and Pearson regression coefficients up to 0.97). This indicates that the low-resolution COCCON instruments are suitable for detecting the aerosol broadband signal contained in the IR spectra in addition to the retrieval of precise trace gas concentrations, provided a robust calibration procedure (Langley-based or absolute calibration procedures) is used to compensate for the optical degradation of the external system (∼ 0.72 % per month). The study also assesses the capability of the EM27/SUN to simultaneously infer aerosols and trace gases and relate their common emission sources in two case study events: a volcanic plume from the La Palma eruption in 2021 and a nearby forest fire in Tenerife in 2022. Overall, our results demonstrate the potential of the portable low-resolution COCCON instruments to enhance the multi-parameter capability of the FTIR technique for atmospheric monitoring.

Thermal and spectroscopic profiles variation of cold-pressed raspberry seed oil studied by DSC, UV/VIS, and FTIR techniques

The characteristics of six cold-pressed raspberry seed oils, investigated by melting and crystallization phase transition analysis using differential scanning calorimetry (DSC), UV–VIS and Fourier transform infrared (FTIR) spectra, as well as the fatty acid composition, was the aim of this study. Two groups of oils samples were investigated: commercial (I-group) and laboratory-pressed (L-group). UV/VIS and FTIR spectra of raspberry seed oil revealed important wavelength and wavenumber ranges to indicate qualitative differences between I- and L-group. Regardless of the scanning rates, DSC melting curves were more suitable for detecting differences in raspberry seed oils than crystallization profiles. Based on the Principal component analysis of UV–VIS, FTIR and DSC data two groups of oils were distinguished. Fatty acids by GC analysis confirmed differences between oils, since the commercial oils exhibited a lower ratio of n-3/n-6 fatty acids than L-group oils. The obtained results provide practical information on the usefulness of DSC profiles and FTIR spectra for the comprehensive characterization of cold-pressed raspberry seed oils, especially in the field of B2B industries that need rapid and non-targeted instruments to confirm the authenticity of the purchased product.

Synthesis, Structural, Spectroscopic, Fluorescence, and Dielectric Studies of Bis-(4-Aminopyridine)-Zinc(II) Acetate: A Metal-Organic Crystal.

The advancement of crystalline growth and characterization tools allows us to investigate novel nonlinear optical substances suitable for photonic applications. Bis-(4-aminopyridine)-zinc(II) acetate (B4AZA), a metal-organic crystal was produced in this study using the slow evaporation procedure at room temperature. Analytical studies such as X-ray crystallography, Fourier transform infrared (FT-IR), UV-visible (UV-Vis), fluorescence, second harmonic generation (SHG), and dielectric tests were used to characterize the as-grown B4AZA crystals. According to the solubility data, the sample has a positive temperature coefficient of solubility. The crystallographic findings show that the B4AZA crystallized in a monoclinic structure with the P21/n space group. Molecular vibrations and functional groups in the substance were determined using the FT-IR technique. The UV-Vis absorbance and transmittance spectra have shown the wide transparency and minimum absorbance of the B4AZA in the near UV and entire visible regions of the electromagnetic spectrum. The bandgap of the B4AZA has been calculated using the Tauc relation and found to be 4.32eV. The fluorescence spectra have shown a prominent emission peak at 584nm with an excitation wavelength of 280nm. The larger Stokes shift found in the fluorescence spectra is advantageous for practical applications. The SHG study revealed that the powdered B4AZA samples generated a second harmonic output. The dielectric test revealed frequency-dependent changes in the dielectric constant and loss factor. Both the dielectric constant and the loss factor decrease exponentially as frequency increases, reaching low values at higher frequencies. The experimental results illustrate the suitability of the B4AZA crystals for photonic applications.

Discrimination of Healthy and Cancerous Colon Cells Based on FTIR Spectroscopy and Machine Learning Algorithms

Colorectal cancer was one of the most frequent causes of death due to cancer in 2020. Current diagnostic methods, based on colonoscopy and histological analysis of biopsy specimens, are partly dependent on the operator’s skills and expertise. In this study, we used Fourier transform infrared (FTIR) spectroscopy and different machine learning algorithms to evaluate the performance of such method as a complementary tool to reliably diagnose colon cancer. We obtained FTIR spectra of FHC and CaCo-2 cell lines originating from healthy and cancerous colon tissue, respectively. The analysis, based on the intensity values of specific spectral structures, suggested differences mainly in the content of lipid and protein components, but it was not reliable enough to be proposed as diagnostic tool. Therefore, we built six machine learning algorithms able to classify the two different cell types: CN2 rule induction, logistic regression, classification tree, support vector machine, k nearest neighbours, and neural network. Such models achieved classification accuracy values ranging from 87% to 100%, sensitivity from 88.1% to 100%, and specificity from 82.9% to 100%. By comparing the experimental data, the neural network resulted to be the model with the best performance parameters, having excellent values of accuracy, sensitivity, and specificity both in the low-wavenumber range (1000–1760 cm−1) and in the high-wavenumber range (2700–3700 cm−1). These results are encouraging for the application of the FTIR technique, assisted by machine learning algorithms, as a complementary diagnostic tool for cancer detection.

Vibrational spectroscopy identifies myocardial chemical modifications in heart failure with preserved ejection fraction

BackgroundVibrational spectroscopy can be a valuable tool to monitor the markers of cardiovascular diseases. In the present work, we explored the vibrational spectroscopy characteristics of the cardiac tissue in an experimental model of heart failure with preserved ejection fraction (HFpEF). The goal was to detect early cardiac chemical modifications associated with the development of HFpEF.MethodsWe used the Fourier-transform infrared (FTIR) and Raman micro-spectroscopic techniques to provide complementary and objective tools for the histological assessment of heart tissues from an animal model of HFpEF. A new sampling technique was adopted (tissue print on a CaF2 disk) to characterize the extracellular matrix.ResultsSeveral spectroscopic markers (lipids, carbohydrates, and glutamate bands) were recognized in the cardiac ventricles due to the comorbidities associated with the pathology, such as obesity and diabetes. Besides, abnormal collagen cross-linking and a decrease in tryptophan content were observed and related to the stiffening of ventricles and to the inflammatory state which is a favourable condition for HFpEF.ConclusionsBy the analyses of tissues and tissue prints, FTIR and Raman techniques were shown to be highly sensitive and selective in detecting changes in the chemistry of the heart in experimental HFpEF and its related comorbidities. Vibrational spectroscopy is a new approach that can identify novel biomarkers for early detection of HFpEF.

Analysis of classical techniques precision on the measurement of cellulose moisture gain/loss.

The precision of the four classical techniques (Karl-Fischer titration, (thermo)gravimetric method, Fourier-transform infrared (FT-IR) and near infrared (NIR) spectroscopies) commonly used in the analysis of cellulose moisture absorption/desorption has been deeply investigated regarding the reproducibility of these processes. Based on multiple repeated experiments, cellulose water content values obtained with Karl-Fischer titration and (thermo)gravimetric method were plotted as a function of time. Then, the cautious peak-by-peak analysis of the absorbance and wavenumber shifts visible in IR spectra has been carried out. The collected data was described using boxplots that provided valuable information on the experimental points spread. It has been successfully proven that gravimetric methods allow for precise drawing of moisture absorption and desorption curves, while Karl-Fischer titration, ATR FT-IR and NIR techniques provide the possibility of the moisture absorption/desorption processes description by linear mathematical models (R2 >90%). Therefore, this study provides a systematic comparison between various analytical methods.

Characterization and discrimination of some gem silicate minerals adopting LIBS, FTIR, and Raman spectroscopic techniques

In this paper, characterization and discrimination of some silicate gems (gemstones and low-gem quality varieties) from ancient Egyptian mines have been performed for the first time adopting molecular and elemental spectroscopic techniques. The selected gem groups are peridot, beryl/emerald, amazonite, and amethyst. In this sense, characterization of the genuine Egyptian gems and the importance of mineralogical and chemical signatures in a historical context as well as the scope of geoheritage can be achieved for the first time. Laser induced breakdown spectroscopy (LIBS) analysis has been found to be an effective method for the discrimination among different gems groups where a characterizing element for each group in a specific spectral window has been found. Raman and Fourier transform infrared (FTIR) spectroscopy spectra have proven to be fingerprints with the ability to distinguish future alteration of the gemstone depending on the molecular vibrational spectroscopy. FTIR provides the functional group that can absorb the infrared radiation and be responsible for the coloring of the gemstones.

Novel UiO-NH2-like Zr-Based MOF (Basu-DPU) as an Excellent Catalyst for Preparation of New 6H-Chromeno[4,3-b]quinolin-6-ones.

A new two-fold interpenetrated pillar-layered metal-organic framework (MOF) was designed and synthesized based on zirconium cations, an amine-functionalized ligand, and a linear exo-bidentate bis-pyridine ligand. The structure of the prepared framework was evaluated using various techniques, such as Fourier transform infrared (FTIR), 13C NMR, energy-dispersive X-ray (EDX), elemental mapping analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), and Brunauer-Emmett-Teller (BET). Then, catalytic application of the prepared zirconium-based MOF was successfully explored in the synthesis of novel 6H-chromeno[4,3-b]quinolin-6-ones 4(a-l) through a one-pot three-component condensation reaction of 4-hydroxycumarine, 1-naphthylamine, and aromatic aldehydes under solvent-free conditions at 110 °C. The pure products were obtained with high atom efficiency (AE) and short reaction times and characterized by FTIR, NMR, and mass spectrometry techniques.

Improvement of non-fat yogurt gel syneresis by heat-unfolded whey protein isolate/mogrosides complexes: Effect on the structural characterization through simultaneous rheological and FTIR techniques

The investigation explores the structural changes and gel properties of heat-unfolded whey protein isolate (PWPI) with mogrosides (MFE) through the simultaneous rheological and fourier transform infrared (FTIR) techniques. The PWPI/MFE complexes potential application in non-fat yogurt were also detected. The results showed that MFE significantly increased the average particle size of the PWPI/MFE complexes and decrease the absolute zeta potential (P < 0.05). Complex formation was evidenced by protein structural changes when PWPI was bound to MFE. Multi-spectral analysis indicated that different MFE concentrations caused protein unfolding and the increase of a disordered structure. The simultaneous rheological and FTIR techniques indicated that the gel properties of PWPI/MFE complexes were much higher than that of PWPI. After addition of MFE, the bands at 2961, 1525, 1351, 1392, 1236 cm−1 occurred simultaneously. The microstructure of the PWPI added with 5 mg/mL MFE exhibited a higher degree of interconnectivity and a denser network than that of PWPI. In addition, the addition of 60 mL 10% PWPI/MFE complexes could significantly improve the syneresis, rheological properties and microstructure of non-fat yogurt. This study provides a theoretical basis for applying PWPI/MFE complexes as a food additive in developing the non-fat dairy foods.

Eco-Friendly Photoreversible Adhesives Derived from Coumarin-Functionalized Epoxy Soybean Oil

The increasing demand for high-performance thermosetting adhesive materials is causing the continuous depletion of fossil reserves and has led to environmental pollution by accumulating recalcitrant plastic waste as thermosetting polymer networks are hard to recycle or reuse. This is particularly true in the case of their use as adhesives, where not only can a crosslinked adhesive not be recovered but multi-material components and devices can be difficult to readily separate, making reuse and recycling complex. Bio-based feedstocks and reusable polymeric materials can start to address these issues and reduce their environmental impact. In this work, we developed sustainable green adhesives which are reversible in architecture (changing from thermoset to non-crosslinked material) by combining bio-renewable epoxidized soybean oil (ESO) and non-toxic coumarins, which can readily undergo reversible [2 + 2] cycloaddition reaction under the appropriate wavelength of UV light. A series of coumarin-modified ESO materials were synthesized and chemically characterized by 1H NMR, 13C NMR, Fourier-transform infrared (FTIR) spectroscopy, and gel permeation chromatography. The extent and kinetics of the polymerization of all systems were monitored and calculated using UV–visible spectroscopy. The photoreversibility of these synthesized polymer networks was also chemically investigated and quantified with UV–visible spectroscopy and FTIR techniques. The physical properties of the materials were tested as well as their ability to heal defects such as scratches on the surface when stimulated by the appropriate UV light. Systems with a more flexible coumarin arm showed a superior adhesion strength with a measurable lap shear strength of 3.1 MPa with a minimum of 0.045 J cm–2 dose of 365 nm UV irradiation and with an excellent reuse efficiency of 94%.

Quantitative characterization of water transport and wetting patterns in coal using LF-NMR and FTIR techniques

Water injection in coal seams is an effective technique for preventing and controlling dust disasters in coal mines. However, there is a lack of quantitative evaluation of water transport in coal and its wetting effect. In this paper, the wetting experiments of coal samples with different coal rank and particle size at a given water volume were characterized using low-field nuclear magnetic resonance (LF-NMR) tests. Additionally, the physicochemical properties of coal were investigated by Fourier transform infrared (FTIR) and low temperature N2 adsorption (LTNA) experiments, establishing quantitative relationships between these properties and contact angle, T2-weighted average value (T2g), and peak area of adsorbed water (ATotal). The relationships reveal the dynamic transport process of water in coal samples and its wettability law. The results show that the relaxation time of free state water in porous media decreases with stronger wetting of coal samples, resulting in a faster relaxation rate of free state water and a leftward shift of corresponding peaks. In the range of coal particle sizes from 0.18 to 2 mm (10–80 mesh), the wettability of coal deteriorates with the increasing degree of deterioration of coal samples, with larger particles of lower rank coal samples exhibiting better wettability. The better the wettability of the coal, the shorter the relaxation time of the corresponding peaks, the larger the total area of the adsorption peaks, and the smaller the T2g,24h values. The FTIR structural parameters of hydroxyl (–OH) and carboxyl (–COOH) groups have the greatest influence on the hydrophilicity of the coal. Correlations of factors affecting the wettability of the coal body were analyzed, and three equations for quantitative characterization of the wettability of the coal body were constructed. Overall, the low-field NMR method presented in this paper provides an efficient means of quantitatively characterizing coal wettability and revealing the macro and microscopic mechanisms underlying the interaction between coal and water, as well as the associated wettability patterns.

FTIR and multivariate analysis of total phenolic content, antioxidant and anti-amylase activities of extracts and milk of Glycine max L. and Phaseolus vulgaris L.

BackgroundAlpha-amylase is a digestive enzyme which hydrolyses the glycosidic bonds in polysaccharides into monosaccharides. Inhibition of α-amylase can help to retard carbohydrate digestion in the small intestine and decrease blood glucose level. The effect of solvent extraction and milk processing on total phenolic content (TPC), antioxidant and anti-amylase activities, and Fourier-transform infrared (FTIR) spectra of Glycine max L. and Phaseolus vulgaris L. were estimated by Principal Component Analysis (PCA) and Partial Least Squares Structural Equation Modelling (PLS-SEM). ResultsThe result showed that the aqueous extract of P. vulgaris L. had the greatest antioxidant activity and anti-amylase activity, while the ethanol extract of G. max L. showed the greatest TPC. Interestingly, the milk of P. vulgaris L. seed showed the greatest level of TPC, antioxidant activity and anti-amylase activity. Mixed milk of G. max L. and P. vulgaris L. (8:2 v/v) showed high anti-amylase activity, while the mixed milk (5:5 v/v) showed high TPC and antioxidant activity. The FTIR result showed five wavenumber ranges associated with functional groups of phenolic compounds. Moreover, the PLS-SEM result revealed a significant positive correlation between TCP and FTIR data (β = 0.335, t = 2.112, p-value < 0.05), and between TCP and antioxidant activity (β = 0.346, t = 2.150, p-value < 0.05). ConclusionsThe result indicated that the solvent types and cooked beans could affect the biological activities and chemical content. The application of chemical content, biological activities, and FTIR technique combined with PLS-SEM and PCA analysis could discriminate bean types, solvent types, and between raw and cooked beans.How to cite: Thummajitsakul S, Paensanit P, Saeieo T, et al. FTIR and multivariate analysis of total phenolic content, antioxidant and anti-amylase activities of extracts and milk of Glycine max L.and Phaseolus vulgaris L. Electron J Biotechnol 2023;64. https://doi.org/10.1016/j.ejbt.2023.04.001.