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Interaction of Zinc Oxide and Copper Oxide Nanoparticles with Chlorophyll: A Fluorescence Quenching Study
摘要： The present study aims to investigate the interactions of zinc oxide nanoparticles and copper oxide nanoparticles with the major photosynthetic pigment chlorophyll using ultraviolet-visible, steady state, and time resolved laser induced fluorescence spectroscopy. The steady state fluorescence measurements show that zinc oxide and copper oxide nanoparticles quench the fluorescence of chlorophyll in concentration-dependent manner. The Stern-Volmer plot for the chlorophyll-zinc oxide nanoparticles is linear, and the value of quenching constant has been observed to increase with temperature indicating the possibility of dynamic quenching. A decrease in the lifetime of chlorophyll with increase in the concentration of zinc oxide nanoparticles confirms the involvement of dynamic quenching in the chlorophyll–zinc oxide nanoparticle interaction. In the case of copper oxide nanoparticles, the Stern-Volmer plot deviates from linearity observed in the form of upward curvature depicting the presence of both static and dynamic quenching. In addition, the lifetime of chlorophyll decreases with increase in the concentration of copper oxide nanoparticles displaying the dominance of dynamic quenching in the chlorophyll-copper oxide nanoparticle interaction. The decrease observed in the value of binding constant with increasing temperature and negative values of change in enthalpy, entropy, and Gibb’s free energy indicates that van der Waal and hydrogen bonding are the prominent forces during the interaction of chlorophyll with both zinc oxide and copper oxide nanoparticles and that the process is spontaneous and exothermic. The interaction of zinc oxide and copper oxide nanoparticles with chlorophyll occurs through electron transfer mechanism. The obtained results are useful in understanding the sensitization processes involving chlorophyll and zinc oxide and copper oxide nanoparticles.
关键词： chlorophyll and nanoparticles,molecular interaction,ultraviolet-visible spectroscopy,laser-induced fluorescence spectroscopy,Attenuated total reflectance–Fourier transform infrared spectroscopy,steady state and time resolved fluorescence,X-ray diffraction
更新于2025-09-19 17:15:36
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Multivariate and machine learning approaches for honey botanical origin authentication using near infrared spectroscopy
摘要： In this work the feasibility of near infrared spectroscopy was evaluated combined with chemometric approaches, as a tool for the botanical origin prediction of 119 honey samples. Four varieties related to polyfloral, acacia, chestnut, and linden were first characterized by their physical–chemical parameters and then analyzed in triplicate using a near infrared spectrophotometer equipped with an optical path gold reflector. Three different classifiers were built on distinct multivariate and machine learning approaches for honey botanical classification. A partial least squares discriminant analysis was used as a first approach to build a predictive model for honey classification. Spectra pretreatments named autoscale, standard normal variate, detrending, first derivative, and smoothing were applied for the reduction of scattering related to the presence of particle size, like glucose crystals. The values of the descriptive statistics of the partial least squares discriminant analysis model allowed a sufficient floral group prediction for the acacia and polyfloral honeys but not in the cases of chestnut and linden. The second classifier, based on a support vector machine, allowed a better classification of acacia and polyfloral and also achieved the classification of chestnut. The linden samples instead remained unclassified. A further investigation, aimed to improve the botanical discrimination, exploited a feature selection algorithm named Boruta, which assigned a pool of 39 informative averaged near infrared spectral variables on which a canonical discriminant analysis was assessed. The canonical discriminant analysis accounted a better separation of samples according to the botanical origin than the partial least squares discriminant analysis. The approach used has permitted to achieve a complete authentication of the acacia honeys but not a precise segregation of polyfloral ones. The comparison between the variables important in projection and the Boruta pool showed that the informative wavelengths are partially shared especially in the middle and far band of the near infrared spectral range.
关键词： botanical origin,Honey,near infrared spectroscopy,support vector machine,variable importance in projection,canonical discriminant analysis
更新于2025-09-19 17:15:36
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Non-destructive prediction of ‘Valencia’ orange ( <i>Citrus sinensis</i> ) and ‘Star Ruby’ grapefruit ( <i>Citrus</i> × <i>paradisi</i> Macfad) internal quality parameters using Vis/NIRS
摘要： Commercial maturity of citrus fruit is measured by sweetness and flavour parameters, which involve the use of destructive, inconsistent, time consuming and expensive techniques such as titrations and destructive refractometer-based juice analysis. New approaches to substitute these techniques involve the application of non-destructive prediction of quality attributes. The ability of visible to near infrared spectroscopy (Vis/NIRS) to non-destructively quantify total soluble solids (TSS), titratable acidity (TA), TSS:TA ratio and BrimA (balance between sugars and acids) of 'Valencia' orange and 'Star Ruby' grapefruit was evaluated. BrimA is an organoleptic parameter considered highly correlated to citrus sweetness and flavour which better aligns with prediction of human perception of good taste. The most accurate model for predicting BrimA was achieved on 'Valencia' orange (R2=0.9576; RMSEP=0.006; RPD=3.96) over 'Star Ruby' grapefruit (R2=0.858; RMSEP=0.429; RPD=2.45). Other parameters were also predicted with high accuracy. This study demonstrated the ability of Vis/NIRS, combined with chemometrics, to non-destructively predict sweetness and flavour attributes of oranges and grapefruit. Commercial application of NIRS models for predicting citrus fruit internal quality parameters prior to pricing of fruit was suggested as a tool for increasing reliability between suppliers and consumers.
关键词： citrus flavour,BrimA,maturity index,near infrared spectroscopy
更新于2025-09-19 17:15:36
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In-line near infrared spectroscopy for the prediction of moisture content in the tapioca starch drying process
摘要： Moisture content is an important parameter measured in tapioca starch production as this parameter has been shown to correlate strongly with the quality of the ?nished product. However, there is currently no in-line sensor which can be used to directly measure the moisture content of the product in real time. The objective of the present work was to study the use of an in-line measurement which can be introduced at the end of the drying process for tapioca starch moisture content evaluation. Either in-line NIR data or at-line NIR data was used to develop the necessary calibration models for evaluating the moisture content. Furthermore, calibration models were also developed by pooling the in-line and at-line data. Its performance was then veri?ed using additional in-line data. The NIR model developed using 100% of the at-line data and 50% of the in-line data was validated using the unused 50% of the inline data. This model was shown to provide better performance in moisture content prediction with an SEP of 0.61% and a bias of 0.001%. In addition, the results showed that the at-line spectrum can also be used for the calibration model development to predict the moisture content of the samples scanned by an in-line spectrometer. However, the in-line spectrometer installation on a pneumatic conveying circular tube where tapioca starch and air mixed was found to be complicated due to signi?cant vibration. This caused additional variation in the data with time. Therefore, it is concluded that the most suitable place for installing a spectrometer would be at a position involving a low pressure, or where the stream ?ow of a product is steadier in order to avoid the dynamic mixing of the product within the drying tube affecting the uncertainty of NIR scattering during the measurement.
关键词： Moisture content,Tapioca starch,Drying process,In-line near infrared spectroscopy
更新于2025-09-19 17:15:36
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On the Decomposition of Carbonate-Based Lithium-Ion Battery Electrolytes Studied Using Operando Infrared Spectroscopy
摘要： A novel infrared diagnostic for operando measurements of electrolyte decomposition is reported. The diagnostic was used to study the decomposition of LiPF6/EC/DEC electrolyte in LCO/graphite Li-ion cells. During formative cycles spectra revealed electrochemical reduction of the EC carbonyl group, which corresponded to simultaneous SEI formation on the graphite anode. This observation supplements current theories of EC decomposition during SEI formation. Operating LCO half-cells at voltages above 4.2 V caused permanent battery capacity loss but no observable electrolyte degradation, indicating the LCO electrode is degraded at high voltage. Infrared thermometry was used to measure the temperature of the electrolyte during heated tests. Operating cells at temperatures above 70°C resulted in SEI and electrolyte decomposition. Operando spectra collected during heating revealed EC ring-opening as the mechanism of thermal degradation, which resulted in permanent capacity loss. EC thermal decomposition was identical in all cells tested, indicating a homogeneous decomposition reaction independent of electrode material or potential. Thermal stability decreased with increased salt concentration indicating that decomposition is likely catalyzed by LiPF6 decomposition products. Thus, thermal decomposition is not caused by continued reduction reactions on the anode due to SEI failure, as EC reduction and EC thermal decomposition have different mechanisms.
关键词： SEI formation,operando infrared spectroscopy,thermal stability,lithium-ion batteries,electrolyte decomposition
更新于2025-09-19 17:15:36
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Aging effects on prefrontal cortex oxygenation in a posture-cognition dual-task: an fNIRS pilot study
摘要： Background: The aging process alters upright posture and locomotion control from an automatically processed to a more cortically controlled one. The present study investigated a postural-cognitive dual-task paradigm in young and older adults using functional Near-Infrared Spectroscopy (fNIRS). Methods: Twenty healthy participants (10 older adults 72 ± 3 y, 10 young adults 23 ± 3 y) performed a cognitive (serial subtractions) and a postural task (tandem stance) as single-tasks (ST) and concurrently as a dual-task (DT) while the oxygenation levels of the dorsolateral prefrontal cortex (DLPFC) were measured. Results: In the cognitive task, young adults performed better than older adults in both conditions (ST and DT) and could further increase the number of correct answers from ST to DT (all ps ≤ 0.027) while no change was found for older adults. No significant effects were found for the postural performance. Cerebral oxygenation values (O2Hb) increased significantly from baseline to the postural ST (p = 0.033), and from baseline to the DT (p = 0.031) whereas no changes were found in deoxygenated hemoglobin (HHb). Finally, the perceived exertion differed between all conditions (p ≤ 0.003) except for the postural ST and the DT (p = 0.204). Conclusions: There was a general lack of age-related changes except the better cognitive performance under motor-cognitive conditions in young compared to older adults. However, the current results point out that DLPFC is influenced more strongly by postural than cognitive load. Future studies should assess the different modalities of cognitive as well as postural load.
关键词： Attention,Functional near-infrared spectroscopy (fNIRS),Postural control,Aging,Dual-tasking,Executive control,Balance,Elderly
更新于2025-09-19 17:15:36
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Optimisation of the Quantification of Total Soluble Solids, pH and Titratable Acidity in South African Grape Must using Fourier Transform Mid-infrared Spectroscopy
摘要： Calibration models for Fourier transform mid-infrared (FT-MiR) spectroscopy were developed for the simultaneous quantification of total soluble solids (TSS, measured as °Brix), pH and titratable acidity (TA, expressed as g/L tartaric acid) in South African (SA) grape must. An exploratory data analysis of the FT-MIR spectra of 1170 grape must samples (647 for °Brix, 252 for pH and 271 for TA) was done by principal component analysis, and partial least squares regression was used for the computation of the regression models. The prediction errors for TSS (0.34 °Brix), pH (0.04 units) and TA (0.51 g/L) provided analytical data of satisfactory accuracy. The evaluation of ready-to-use global calibrations to quantify these three parameters in SA samples presented standard error of prediction (SEP) values of 0.46°Brix, 0.10 pH units and 3.13 g/L for TA. After slope and intercept adjustments of the original global calibration algorithms, the SEP values were reduced to 0.38 °Brix, 0.05 pH units and 0.49 g/L for TA. These results show the necessity for optimisation of the global FT-MIR WineScan calibrations to provide a better fit to samples of South African origin. The results demonstrate that FT-MiR spectroscopy is a useful technique for the rapid quantification of major grape must parameters and for quality control purposes in an industrial cellar.
关键词： wine grape chemical analysis,Fourier transform infrared spectroscopy,chemometrics
更新于2025-09-19 17:15:36
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Influence of Sample Mixing Techniques on Engine Oil Contamination Analysis by Infrared Spectroscopy
摘要： For the most reliable and reproducible results for calibration or general testing purposes of two immiscible liquids, such as water in engine oil, good emulsi?cation is vital. This study explores the impact of emulsion quality on the Fourier transform infrared (FT-IR) spectroscopy calibration standards for measuring water contamination in used or in-service engine oil, in an attempt to strengthen the speci?c guidelines of ASTM International standards for sample preparation. By using different emulsi?cation techniques and readily available laboratory equipment, this work is an attempt to establish the ideal sample preparation technique for reliability, repeatability, and reproducibility for FT-IR analysis while still considering the ease and ef?ciency of the technique. This study demonstrates that a stable emulsion within a sample, which depends heavily upon the method, provides a reliably consistent homogenous sample for quanti?cation purposes with FT-IR analysis. Analysis of variance (ANOVA) modeling and limit of detection calculations demonstrate the stability of the emulsion. The results reveal that setting a mixing time for a calibration standard depends on the emulsi?cation process. Inserting a probe directly into a sample (direct sonication) allows for a rapid, stable emulsion with high reproducibility. Indirect sonication produces relatively non-miscible liquids of different densities. The pan-shaker produces a reasonably stable emulsion, but without the long-term stability or quick production time of direct sonication. Reaction time plays a critical role in the rotary mixing method, which leads to a slow development of emulsi?cation.
关键词： mixing methods,lubricating oils,emulsion,water contamination,infrared spectroscopy
更新于2025-09-19 17:15:36
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Conducting Hyperscanning Experiments with Functional Near-Infrared Spectroscopy
摘要： Concurrent brain recordings of two or more interacting persons, an approach termed hyperscanning, are gaining increasing importance for our understanding of the neurobiological underpinnings of social interactions, and possibly interpersonal relationships. Functional near-infrared spectroscopy (fNIRS) is well suited for conducting hyperscanning experiments because it measures local hemodynamic effects with a high sampling rate and, importantly, it can be applied in natural settings, not requiring strict motion restrictions. In this article, we present a protocol for conducting fNIRS hyperscanning experiments with parent-child dyads and for analyzing brain-to-brain synchrony. Furthermore, we discuss critical issues and future directions, regarding the experimental design, spatial registration of the fNIRS channels, physiological influences and data analysis methods. The described protocol is not specific to parent-child dyads, but can be applied to a variety of different dyadic constellations, such as adult strangers, romantic partners or siblings. To conclude, fNIRS hyperscanning has the potential to yield new insights into the dynamics of the ongoing social interaction, which possibly go beyond what can be studied by examining the activities of individual brains.
关键词： neuroscience,brain-to-brain synchrony,cooperation,fNIRS,parent-child interaction,hyperscanning,functional near-infrared spectroscopy
更新于2025-09-19 17:15:36
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Biomedical applications of mid-infrared quantum cascade lasers – a review
摘要： Mid-infrared spectroscopy has been applied to research in biology and medicine for more than 20 years and conceivable applications have been identified. More recently, these applications have been shown to benefit from the use of quantum cascade lasers due to their specific properties, namely high spectral power density, small beam parameter product, narrow emission spectrum and, if needed, tuning capabilities. This review provides an overview of the achievements and illustrates some applications which benefit from the key characteristics of quantum cascade laser-based mid-infrared spectroscopy using examples such as breath analysis, the investigation of serum, non-invasive glucose monitoring in bulk tissue and the combination of spectroscopy and microscopy of tissue thin sections for rapid histopathology.
关键词： quantum cascade lasers,glucose monitoring,mid-infrared spectroscopy,histopathology,breath analysis,biomedical applications
更新于2025-09-19 17:15:36