Search Results (204)

The combination of Fourier-transform infrared (FTIR) spectroscopy and machine learning gives a promising result in wheat variety classification. This study aimed to evaluate the contributions of distinct spectral regions and their combinations to classification performance. Out of the full raw spectra of four bread wheat varieties, namely Altindane, Cavus, Flamura-85, and Nevzatbey, 15 spectral datasets were prepared. Artificial Neural Networks (ANN), Support Vector Machines (SVM), Random Forest (RF), and K-Nearest Neighbor (KNN) models were trained and analyzed. The highest classification performance was obtained using spectral regions associated with protein and lipid bands. The highest average accuracy of 0.9895 was shown by the SVM model, while the ANN produced comparable results with lower variability. Additionally, Variable Importance in Projection (VIP) analysis identified the most influential spectral bands in the protein (Amide II, ~1542 cm⁻¹) and carbonyl (1744–1715 cm⁻¹) regions. These findings indicate that classification is driven by chemically meaningful features rather than purely statistical patterns. The approach followed in this study provides an insight that, in FTIR-based classification, when rigorously evaluated using nested cross-validation, spectral region selection can outweigh model complexity. This approach demonstrates strong potential for rapid and non-destructive assessment, especially for real-time applications in grain processing and automated sorting systems. Full article

Bone formation requires a substantial energy supply to sustain extracellular matrix production and mineralization, yet the temporal contribution of lipid metabolism during osteoblast maturation remains incompletely characterized. This study investigated the molecular and transcriptional remodeling of lipid metabolism. Intracellular lipid distribution was analyzed by confocal microscopy using Nile Red staining. Transcriptional modulation of lipid synthesis, storage, lipolysis, genes associated with mitochondrial fatty acid oxidation, and osteogenic markers were assessed by quantitative real-time PCR, and the biochemical composition was evaluated by Raman spectroscopy. Early stages of spheroid development showed higher expression of genes involved in lipid synthesis and storage (FASN, DGAT2, and PLIN2) together with intracellular lipid accumulation, whereas later stages displayed increased expression of lipolytic and β-oxidation markers (PNPLA2/ATGL, CPT1A, and HADHA), accompanied by the redistribution of lipid droplets. The Raman analysis revealed a time-dependent variation of lipid-associated CH₂/CH₃ bands and modulation of protein-related Amide I–III signals, consistent with biochemical remodeling during maturation. Overall, the data indicate a coordinated transcriptional shift from lipid accumulation-associated pathways toward lipid mobilization during osteogenic progression in a 3D culture. This model provides a controlled experimental platform for investigating metabolic regulation during bone formation and for studying metabolic alterations associated with skeletal disorders. Full article

Protein-based films are promising biodegradable materials, but their performance is often limited by structural instability during storage. In this study, blend films were developed from myofibrillar proteins of giant squid (Dosidicus gigas) and whey protein concentrate (WPC) to improve functional properties and evaluate stability during three months of storage. The effects of plasticizer type (glycerol or sorbitol) and WPC concentration (5–15%) on film structure and performance were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), optical measurements, solubility, and water vapor transmission rate (WVTR). FT-IR revealed a transition from α-helix to β-sheet structures, indicating stronger protein–protein interactions, particularly in sorbitol-plasticized films. This structural organization improved barrier properties, reducing WVTR from 44.2 g·m⁻²·d⁻¹ in squid protein films to 18.9 g·m⁻²·d⁻¹ in films containing WPC. Light transmittance analysis showed that all films acted as effective UV barriers, with transmission starting near 350 nm. At this wavelength, transmittance ranged from 5–17% in sorbitol-plasticized films to 33–46% in glycerol-plasticized films. Increasing WPC concentration also reduced film solubility, indicating the formation of a more compact protein matrix. During three months of storage, FT-IR spectra revealed changes in the Amide A and Amide III bands associated with plasticizer migration and increased protein–protein interactions. Transparency increased during storage, indicating progressive structural reorganization, while the UV barrier properties remained stable. These results demonstrate that blending squid and whey proteins, particularly with sorbitol as plasticizer, produces biodegradable films with improved barrier properties and good structural stability during storage, highlighting their potential for sustainable food packaging applications. Full article

This study investigated the effects of boiling, roasting, and frying on the quality and flavor characteristics of Shiqi pigeon (Columba livia domestica) meat. Changes in color, texture, microstructure, and volatile profiles were systematically evaluated using colorimetry, texture profile analysis, scanning electron microscopy, electronic nose analysis, and Fourier transform infrared spectroscopy (FTIR). Thermal processing significantly influenced physicochemical properties and flavor profiles. Fried samples exhibited the highest hardness (27.79 N), chewiness (33.13 mJ), and maximum shear force (30.23 N), while boiled samples showed the lowest hardness (22.12 N) and puncture hardness (12.20 N), indicating improved tenderness. Electronic nose PCA explained 85.4% of total variance (PC1: 59.5%; PC2: 25.9%), clearly discriminating the three treatments. Color measurements showed that frying induced the greatest total color difference (ΔE > 1, p < 0.05), followed by roasting and boiling. FTIR analysis revealed pronounced shifts in amide I bands in fried samples, indicating stronger protein secondary structure alterations. Overall, different thermal processing methods produced distinct quality and flavor characteristics in pigeon meat, providing scientific guidance for process optimization and product development. Full article

Mid-infrared (MIR) femtosecond lasers, resonant with the absorption bands of amide-related molecular groups in the range of 6.1 to 6.5 μm, have been demonstrated to be effective for tissue ablation. However, the flexible and stable delivery of such pulses to micrometer-scale tissue regions for controlled ablation remains challenging. Here, we utilize a silica-based anti-resonant hollow-core fiber (AR-HCF) to deliver high-power MIR femtosecond pulses with high temporal and spectral fidelity, featuring pulse durations of approximately 340 fs and peak power densities exceeding 1 GW/cm², for selective tissue ablation. Benefiting from the small numerical aperture of the AR-HCF, a relatively stable and consistent beam spot size can be maintained over a millimeter-scale propagation distance. Precise control of the ablation depth can be achieved by appropriately selecting the scanning parameters, with penetration depths reaching the sub-millimeter scale. Furthermore, for the first time, we systematically compare the tissue ablation performance of MIR femtosecond lasers at resonant wavelengths (6.4 and 6.1 μm) and a non-resonant wavelength (5.5 μm) under identical scanning conditions. An ablation depth ratio of more than 8:1 is observed, demonstrating the high efficiency and selectivity of the resonance-based ablation mechanism. These results establish flexible delivery of high-power MIR femtosecond pulses in tissue-resonant bands via silica-based AR-HCF as a powerful platform for selective, precise, and efficient tissue ablation, providing a promising approach for interventional and minimally invasive surgery. Full article

Microbial degradation technology presents a sustainable approach to address the environmental persistence of polyethylene (PE). In this study, a consortium of PE-degrading strains was isolated from sludge in the production wastewater of a PE-manufacturing plant. Among these strains, Pseudomonas aeruginosa SG01 demonstrated the highest cellular growth rate in culture medium, indicating its capacity to efficiently degrade PE and utilize it as the sole carbon source. Following treatment with SG01, the PE films exhibited a significant reduction in mass along with a clear decrease in surface contact angle, suggesting an improvement in hydrophilicity. Fourier transform infrared spectroscopy (FTIR) analysis detected the formation of new absorption bands on the treated PE films, corresponding to hydroxyl, carboxyl, and amide functional groups. Scanning electron microscopy (SEM) observations further revealed the presence of erosion pits and network-like cracks on the film surface. This study confirms that Pseudomonas aeruginosa SG01 can effectively degrade PE and modify its surface properties, offering a novel microbial resource for the bioremediation of PE contamination. Full article

The rapid and selective discrimination of microplastics (MPs) is a critical analytical challenge, particularly as current carbon quantum dot (CQD)-based sensors often rely on single-wavelength “turn-on/off” or staining mechanisms that lack polymer-specific resolution. This work addresses these limitations by presenting a mechanism-driven fluorescence sensing platform using ultra-fine polyamide-derived carbon quantum dots (PACQDs; ~1.4 nm) to identify three prevalent MPs: polyamide (PA), polypropylene (PP), and polyethylene terephthalate (PET). Excitation–emission matrix (EEM) spectroscopy reveals polymer-specific photophysical responses: PAMPs and PPMPs induce fluorescence enhancement of 11.66% and 11.43%, respectively, whereas PETMPs cause net quenching (−4.61%) alongside a distinct, red-shifted emission band. Despite a common scatter-dominated peak at 290/308 nm, quantitative discrimination is achieved via integrated intensity and red/blue emission ratios (0.0137 for PAMPs, 0.0098 for PPMPs, and 0.0072 for PETMPs). Multivariate analysis reinforces this discrimination. Parallel factor analysis (PARAFAC) resolves the EEM data into three fluorescent components representing the intrinsic CQDs core and two interaction-induced surface states with a rank 3 model reducing the relative reconstruction error from 0.1625 to 0.1285. Principal component analysis (PCA) yields clear separation of the polymer classes, with the first two principal components capturing ~88% of the total spectral variance. ATR–FTIR spectroscopy provides direct molecular evidence for the underlying mechanisms: amide–amide coupling and interfacial rigidification for PAMPs; hydrophobic interaction without spectral shifts for PPMPs; and a synergistic interaction involving hydrogen bonding and π–π stacking for PETMPs. In particular, these polymer-specific fluorescence fingerprints are largely preserved in tap water, despite elevated background intensity and partial contrast attenuation, demonstrating the resilience of the EEM–chemometric approach under realistic matrix conditions. Collectively, the strong agreement between fluorescence metrics, multivariate signatures, and interfacial chemistry establishes a robust structure–property framework and positions PACQDs as a rapid, label-free, and matrix-tolerant platform for reliable microplastic discrimination in environmental analysis. Full article

This study investigates the synthesis and physicochemical characterization of biolubricant base oils derived from sunflower oil methyl esters (SUNOMEs) via transesterification with trimethylolpropane (TMP) using guanidine carbonate (GNDC) as a green and efficient catalyst. The transesterification process was optimized to achieve high conversion and desirable physicochemical properties suitable for lubrication applications. The synthesized esters were characterized by viscosity, density, pour point, and oxidation stability, confirming their suitability as environmentally friendly lubricants. Reaction parameters, such as catalyst concentration (3.0–5.0 wt%), were optimized under both solvent-free and vacuum-assisted conditions. The use of guanidine carbonate achieved enhanced physicochemical properties with significantly reduced reaction times (≈6 h) and eliminated soap formation. The resulting TMP triesters exhibited kinematic viscosities in ranges of 41.27–52.73 cSt (40 °C) and 8.668–10.02 cSt (100 °C), a viscosity index in the range of 180–196, and excellent oxidation stability (RSSOT: up to 54.27 min). Fourier transform infrared (FTIR) analysis confirmed the formation of complete triester structures with characteristic carbonyl and C–O stretching bands at 1735 cm⁻¹ and 1050 cm⁻¹, respectively. Spectra showed also distinct stretching vibrations near 1640–1670 cm⁻¹ and 3300–3400 cm⁻¹, which correspond to amide carbonyl and N–H characteristic groups. The tribological performance was evaluated using Four-Ball Standard Test Method, demonstrating significant improvements compared to commercial mineral oils. The results indicate that guanidine carbonate is an effective catalyst for producing sunflower-oil-derived esters with favorable lubricating properties, highlighting their potential as sustainable biolubricants for industrial applications. Full article

Terpyridines are well-known ligands in coordination chemistry, are valued for their conformational flexibility and strong metal-binding properties, and are also of interest as fluorophores. This study focused on the synthesis and comprehensive investigation of a new class of bis-oxazolo[5,4-b]pyridine derivatives, designed based on their structural similarity to terpyridines. Four novel compounds, 4a–d, were synthesized by cyclization of amide derivatives of 3-aminopyridin-2(1H)-ones using pyridine-2,6-dicarboxylic acid and its dichloride as key acidic components. Their structures and purity were confirmed by melting point analysis, high-resolution mass spectrometry, and ¹H, ¹³C NMR spectroscopy. Compounds 4a–c exhibit UV absorption at 323–357 nm and intense blue to deep-blue fluorescence (357–474 nm, цi ≈ 0.32–0.84) in chloroform, dichloromethane, and acetonitrile, attributed to p–p* transitions within the conjugated ring system. These findings suggest their potential as phosphors for organic electronics. Computational modeling of 4a–c molecules provided insight into their electronic structures, conformational stability, and predicted optical behavior. The most stable conformers (4a–II, 4b–II, 4c–II′) exhibited a progressive decrease in the HOMO–LUMO gap from 4a to 4c, correlated with the enhancement of photoactivity. Among them, compound 4a stands out as the most promising luminophore, displaying the most intense and narrow luminescence band, owing to its high molecular symmetry and stable emission characteristics. Overall, this study lays the foundation for future studies of bis(oxazolo[5,4-b]pyridine) derivatives in coordination chemistry and optoelectronic materials development. Full article

Background: No Fourier transform infrared (FTIR) spectroscopy studies have directly evaluated adrenalectomy vessels, the technique’s established ability to probe collagen/elastin-associated spectral features and lipid peroxidation-related signatures, and protein structural damage. Stable gastric pentadecapeptide BPC 157 therapy was found to maintain the vascular function under severe stress, as FTIR spectroscopy recently demonstrated rapid peptide-induced molecular changes in healthy rat blood vessels, particularly in lipid content and protein secondary structure. Methods: To extend these findings and highlight the BPC 157 vascular background in the special circumstances of the course following unilateral adrenalectomy, abdominal aortas were collected at 15 min, 5 h, and 24 h after unilateral adrenalectomy for the FTIR spectroscopy assessment. Results: FTIR spectra were acquired, preprocessed, and analyzed using principal component analysis (PCA), support vector machine discriminant analysis (SVMDA), and band-specific statistics. BPC 157 (10 ng/kg intragatrically immediately after unilateral adrenalectomy) produced a clear, reproducible separation of aortic spectra from control samples at all time points. The main discriminatory spectral signatures were observed in three regions, including amide I and amide II (protein-related bands, consistent with collagen/elastin contributions) and lipid C–H stretching bands. These spectral signatures are consistent with early extracellular matrix reinforcement and membrane preservation in the vascular wall and align with the recovering effect on the lesions in counteraction of the severe vascular and multiorgan failure, attenuation/elimination of thrombosis and blood pressure disturbances in various occlusion/occlusion-like syndromes. Conclusions: Together, after unilateral adrenalectomy, the FTIR data provide molecular-level spectral signatures consistent with rapid remodeling of the aortic wall toward a more structurally stable and functionally favorable state. Full article

Two amide-preformed aromatic diamine monomers, N,N-bis(4-(3-aminobenzamido)phenyl)-N’,N’-bis(4-methoxyphenyl)-1,4-phenylenediamine (m-6) and N,N-bis(4-(4-aminobenzamido)phenyl)-N’,N’-bis(4-methoxyphenyl)-1,4-phenylenediamine (p-6), were synthesized and utilized to prepare two series of electroactive poly(amide-imide)s (PAIs) through a two-step polycondensation reaction with commercially available aromatic tetracarboxylic dianhydrides. The obtained polymers exhibited solubility in various polar organic solvents, and most of them could form transparent, flexible films via solution casting. Thermal analysis indicated glass transition temperatures (T_g) ranging from 250 °C to 277 °C, as measured by DSC, with no significant weight loss observed before 400 °C in TGA tests. Cyclic voltammograms (CV) of the polymer films on ITO-coated glass substrates revealed two reversible oxidation redox pairs between 0.67 and 1.04 V vs. Ag/AgCl in an electrolyte-containing acetonitrile solution. The PAI films showed stable redox activity with high optical contrast both in the visible and near-infrared regions, transitioning from colorless in the neutral state to green and blue in the oxidized states. Furthermore, the polymer films retained good electrochemical and electrochromic stability even after more than 100 cyclic switching operations. The PAIs displayed outstanding electrochromic performance, including high optical contrast (up to 95%), rapid response times (below 4.6 s for coloring and 5.7 s for bleaching), high coloration efficiency (up to 240 cm²/C), and low decay in optical contrast (less than 5% after 100 switching cycles for most PAIs). Full article

Amid accelerating climate change, intensifying urban heat island effects, and rising public demand for livable, walkable streets, there is an urgent practical need for interpretable and actionable evidence on streetscape quality. Yet, research on streetscape quality has often relied on single data sources and linear models, limiting insight into multidimensional perception; evidence from temperate monsoon cities remains scarce. Using Tianjin’s main urban area as a case study, we integrate street-view imagery with remote sensing imagery to characterize satellite-derived environmental indicators at the point scale and examine the following five perceptual outcomes: comfort, aesthetics, perceived greenness, summer heat perception, and willingness to linger. We develop a three-step interpretable assessment, as follows: Elastic Net logistic regression to establish directional and magnitude baselines; Generalized Additive Models with a logistic link to recover nonlinear patterns and threshold bands with Benjamini–Hochberg false discovery rate control and binned probability calibration; and Shapley additive explanations to provide parallel validation and global and local explanations. The results show that the Green View Index is consistently and positively associated with all five outcomes, whereas Spatial Balance is negative across the observed range. Sky View Factor and the Building Visibility Index display heterogeneous forms, including monotonic, U-shaped, and inverted-U patterns across outcomes; Normalized Difference Vegetation Index and Land Surface Temperature are likewise predominantly nonlinear with peak sensitivity in the midrange. In total, 54 of 55 smoothing terms remain significant after Benjamini–Hochberg false discovery rate correction. The summer heat perception outcome is highly imbalanced: 94.2% of samples are labeled positive. Overall calibration is good. On a standardized scale, we delineate optimal and risk intervals for key indicators and demonstrate the complementary explanatory value of street-view imagery and remote sensing imagery for people-centered perceptions. In Tianjin, a temperate monsoon megacity, the framework provides reproducible, actionable, design-relevant evidence to inform streetscape optimization and offers a template that can be adapted to other cities, subject to local calibration. Full article

Goat milk can be a vehicle for beneficial microorganisms, such as probiotic lactic acid bacteria (LAB). During lactic fermentation, the hydrolysis of milk proteins can improve their nutritional properties and sensory attributes and even have beneficial health effects. The objective of this study was to evaluate the caseinolytic activity of LAB strains with probiotic potential and to monitor the changes induced by fermentation and during storage in milk components using Fourier transform infrared (FTIR) spectroscopy. First, the proteolytic activity of 36 LAB strains isolated from dairy products was qualitatively assessed. Then, 17 strains with probiotic potential and moderate to high proteolytic activity were selected for further analysis. Casein proteolysis was found to be strain-dependent, with a decrease in total protein concentration ranging from 28% to 87% and an increase in amino acids ranging from 29% to 88%. Furthermore, a notable difference was observed in the amide bands in the FTIR spectra between the beginning and end of incubation, showing a decrease in the intensities of the bands attributed to proteins. In fermented goat milk, LAB growth resulted in a final count between 0.62 and 2.6 log CFU/mL, a 0.29 to 2.0 drop in pH, and lactic acid production between 0.20 and 1 g/L. FTIR spectra revealed time-dependent modifications in amide I and II bands accompanied by a marked reduction in carbohydrate content and an increase in lactic acid signal. After 21 days of storage, the viability of the strains, pH, and lactic acid in the fermented milks were not substantially modified. These results highlight the potential of lactic fermentation with strains selected for their probiotic potential as an approach to producing value-added goat milk products, as well as the usefulness of FTIR spectroscopy for characterizing complex systems such as goat milk. Full article

Rising residential land prices push up housing prices and worsen credit misallocation. These patterns emerge amid cyclical real estate fluctuations and heavy land-based public finance. Such pressures undermine macroeconomic stability and sustainable land-use. The land price circuit breaker is widely applied with a price cap and state dependence, yet its trigger mechanism and interaction with inflation targeting remain underexplored. This study addresses three core questions. First, how does the circuit breaker’s discrete trigger and rule-switching logic differ from traditional static price ceilings? Second, can the mechanism, via the collateral channel, restrain excessive land price hikes, improve credit allocation, and, thereby, stabilize land price dynamics and long-run macroeconomic performance? Third, how does the circuit breaker interact with inflation targeting, and through which endogenous channels does a strict target dampen housing prices and raise activation probability? This study develops a multi-sector DSGE model with an embedded land price circuit breaker. The price cap is modeled as an occasionally binding constraint. A dynamic price band and trigger indicator capture the policy’s switch between slack and binding states. The framework incorporates interactions among local governments, the central bank, developers, and households. It also links firms and the secondary housing market. Under different inflation-targeting rules, this study uses impulse responses, an event study, and welfare analysis to assess trigger conditions and macroeconomic effects. The findings are threefold. First, a strict inflation target increases the probability of a circuit breaker being triggered. It channels housing-demand shocks toward land prices and creates a “nominal anchor–relative price constraint” linkage. Second, once activated, the circuit breaker narrows the gap between land price and house-price growth. It weakens the procyclicality of collateral values. It also restrains credit expansion by impatient households. These effects redirect credit toward firms, improve corporate financing, reduce the decline in investment, and accelerate output recovery. Third, the circuit breaker limits new land supply and shifts demand toward the secondary housing market. This generates a supply-side effect that releases existing stock and stabilizes prices, thereby weakening the amplification mechanism of housing cycles. This study identifies the endogenous trigger logic and cross-market transmission of the land price circuit breaker under a strict inflation target. It shows that the mechanism is not merely a price-management tool in the land market but a systemic policy variable that links the real estate, finance, and fiscal sectors. By dampening real estate procyclicality, improving credit allocation, and stabilizing macroeconomic fluctuations, the mechanism offers new insights for sustainable land-use policy and macroeconomic stabilization. Full article

Myofibrillar protein (MP) aggregation in solutions with NaCl concentrations below 0.3 M results in poor solubility. Ultrasound-assisted glutaminase treatment (UGT) was applied to improve MP solubility in a low-salt solution (containing 0.1 M NaCl). The solubility increased with ultrasonic power and time, peaking at 44.34% (480 W, 15 min) and reaching 61% after UGT. Subsequently, the effect of post-sonication heat treatment (60 °C, 30 min) on the physicochemical and structural characteristics of ultrasound-enzyme treated MP (UEMP), prepared under specific ultrasonic conditions (480 W, 20 min), was systematically investigated. The findings revealed that UEMP exhibited higher hydrophobicity, sulfhydryl content, and turbidity, but reduced particle size, ζ-potential, and fluorescence, suggesting disulfide disruption and exposure of hydrophobic residues. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed weakened high-molecular weight bands and intensified low-molecular weight bands. Fourier-transform infrared spectroscopy confirmed these structural rearrangements, with a blue-shifted amide A band and decreased amide I intensity. Heating further increased the hydrophobicity and fluorescence without altering the size, ζ-potential, or molecular weight. The red shift in the amide A band suggests reinforced local ordering. Rheology analysis showed non-Newtonian shear-thinning behavior, which was unchanged by UGT or heating. Collectively, UGT with moderate heating enhances MP solubility and thermal stability by disrupting stabilizing bonds and modulating the structure. Full article