scholarly journals Chemometrics: An Excavator in Temperature-Dependent Near-Infrared Spectroscopy

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 452
Author(s):  
Yan Sun ◽  
Wensheng Cai ◽  
Xueguang Shao

Temperature-dependent near-infrared (NIR) spectroscopy has been developed and taken as a powerful technique for analyzing the structure of water and the interactions in aqueous systems. Due to the overlapping of the peaks in NIR spectra, it is difficult to obtain the spectral features showing the structures and interactions. Chemometrics, therefore, is adopted to improve the spectral resolution and extract spectral information from the temperature-dependent NIR spectra for structural and quantitative analysis. In this review, works on chemometric studies for analyzing temperature-dependent NIR spectra were summarized. The temperature-induced spectral features of water structures can be extracted from the spectra with the help of chemometrics. Using the spectral variation of water with the temperature, the structural changes of small molecules, proteins, thermo-responsive polymers, and their interactions with water in aqueous solutions can be demonstrated. Furthermore, quantitative models between the spectra and the temperature or concentration can be established using the spectral variations of water and applied to determine the compositions in aqueous mixtures.

2014 ◽  
Vol 3 (3) ◽  
pp. 57 ◽  
Author(s):  
Samantha A. Hawkins ◽  
Brian Bowker ◽  
Hong Zhuang ◽  
Gary Gamble ◽  
Ronald Holser

<p>Chicken meat undergoes significant chemical and structural changes with postmortem time that influence meat quality characteristics. The objective of this study was to measure the visible-near infrared (vis-NIR) spectral differences in broiler breast fillets at 0.5, 4, 24, and 120 h postmortem. Muscle samples were flash frozen and freeze-dried prior to spectra analysis. In the visible region of the spectra (400-700 nm) changes in myoglobin protein peaks were observed with postmortem time. Freeze-drying muscle samples provided additional information from the NIR region of the spectra (800-2500 nm) on muscle protein changes during postmortem aging. Alterations to the b-sheet and a-helix structures of myofibrillar proteins and changes in the amount of bound water were observed in the NIR region with postmortem aging. Data from this study demonstrate that changes in breast fillets with postmortem time that are related to meat quality traits are detectable using vis-NIR spectroscopy.</p>


The Analyst ◽  
2018 ◽  
Vol 143 (18) ◽  
pp. 4306-4315 ◽  
Author(s):  
Pham K. Duy ◽  
Seulah Chun ◽  
Yoonjeong Lee ◽  
Hoeil Chung

The origin of particle size-induced near-infrared (NIR) spectral variation, which is fundamental for robust quantitative analysis, was systematically studied in conjunction with Monte Carlo simulation.


NIR news ◽  
2019 ◽  
Vol 30 (5-6) ◽  
pp. 15-17
Author(s):  
Mian Wang ◽  
Xiaoyu Cui ◽  
Wensheng Cai ◽  
Xueguang Shao

Temperature-dependent near-infrared spectroscopy has been developed for studying quantitative and structural analysis, as well as the molecular interactions. Taking the advantage of the temperature effect on hydrogen bonding, the technique has shown its potential in analyzing the interactions in aqueous solutions. In our recent studies, the structural changes in homo-oligopeptides K5 (penta-lysine), D5 (penta-aspartic acid), and protein (ovalbumin) aqueous solutions were studied by temperature-dependent near-infrared spectroscopy. The thermodynamics and their interaction with water were analyzed with the help of the chemometric methods including continuous wavelet transform, independent component analysis, two-dimensional (2D) correlation analysis, and Gaussian fitting. The results show that the oligopeptide in aqueous solution improves the thermal stability of the water species, and K5 has stronger interaction with water than D5. In the gelation of ovalbumin, the change of the water species with two hydrogen bonds (S2) follows the same phases as the protein. S2 maintains the stability of the protein in native and molten globule states, and the weakening of the hydrogen bond in S2 by high temperature results in the destruction of the hydration shell and makes the ovalbumin clusters form a gel structure.


2017 ◽  
Vol 29 (1) ◽  
pp. 160
Author(s):  
C. K. Vance ◽  
K. R. Counsell ◽  
L. A. Agcanas ◽  
N. Shappell ◽  
S. Bowers ◽  
...  

Aquaphotomics is a branch of near-infrared (NIR) spectroscopy in which bond vibrations from organic molecules and water create unique spectral absorbance patterns to profile complex aqueous mixtures. Aquaphotomics has been shown to detect virus infected soybean plants from extracts, classify probiotic bacteria, and detect contamination of aquatic ecosystems. We have used aquaphotomics to characterise serum profiles from horses in various phases of the reproductive cycle such as oestrus and diestrus. Because serum is a complex solution of biomolecules, various modes of serum processing (e.g. large protein removal for proteomics or mass spectrometry) may provide different NIR spectral profiles for quantitative analysis of specific compounds or their effects. Zearalenone is a fungal mycotoxin that may have estrogenic potential in mares and is found in feedstuffs. The objectives of this study were to (1) establish NIR spectral profiles of serum and protein-precipitated serum (PPS) collected at peak oestrus from mares; (2) determine if NIR profiles correlate and quantify E2 concentrations in serum or PPS; and (3) determine if NIR can detect differences in serum chemistry of zearalenone-treated mares. Mares were fed zearalenone daily at low (2 mg, 2 mares, 5 cycles) and high (8 mg, 1 mare, 3 cycles) concentrations, plus control (0 mg, 1 mare, 3 cycles). Oestrus cycles were monitored by ultrasound and serum hormone analysis. Serum collected at peak oestrus had E2 values determined by radioimmunoassay (range 0.02–16.87 pg mL−1). Protein precipitated serum had high and medium MW proteins removed with acetonitrile. NIR spectra, collected in triplicate with a 1 mm quartz cuvette and ASD FieldSpec®3 (Boulder, CO, USA), were pre-treated with a Savitsky-Golay 1st derivative for inspection of spectral features, principal component analysis, and partial least-squares regression (PLS) to investigate spectral correlations to E2 concentrations and zearalenone treatment effects. The NIR profiles contrasting serum and PPS at oestrus had distinct spectral features differing significantly at 1320, 1491, 1536, and 1566 nm in the NIR water spectrum, and principal component-1 accounted for 97% of principal component analysis variance in spectra from serum compared to PPS. In the PLS cross-validation linear fit regression model, NIR predicted E2 concentrations (validated by RIA) from serum (slope = 0.89, SECV = 1.92, R2 = 0.81, 3 factors), and from PPS (slope = 0.61; SECV = 1.84, R2 = 0.76, 4 factors). Spectral predictions were poorest at the low E2 threshold, E2 = 0.02 pg mL−1. The PLS model validation metrics of zearalenone dose-dependent effects were also evident in serum (slope = 0.88, SECV = 1.26, R2 = 0.86) and in PPS (slope = 0.67, SECV = 1.96, R2 = 0.66). Correlations of quantitative values of E2 and zearalenone were both better for spectra taken of serum compared to PPS. In summary, NIR spectral profiles of serum chemistry may be able to map E2 hormone levels during reproductive cycling, and these spectra may also have correlations that reflect exposure of mares to estrogenic toxins such as zearalenone. Research was supported by USDA-ARS Biophotonics grant #58-6402-3-018.


Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1689
Author(s):  
Carmen-Mihaela Popescu ◽  
Nanami Zeniya ◽  
Kaoru Endo ◽  
Takuma Genkawa ◽  
Miyuki Matsuo-Ueda ◽  
...  

Sitka spruce wood samples were subjected to different conditions of hydro-thermal treatment by varying the relative humidity (RH) and period of exposure at a constant temperature of 120 °C. Near infrared (NIR) spectroscopy, principal component analysis (PCA) and two dimensional correlation spectroscopy (2D-COS) were employed to examine the structural changes which occur in the wood samples during the applied treatment conditions and to quantify the differences between non-extracted and water-extracted wood specimens after the treatment. Modifications were dependent on the amount of water molecules present the medium and also on treatment time. Higher variations were observed for samples treated at higher RH values and for longer periods. At the same time, it was also observed that during the hydro-thermal treatment a high amount of extractives remain in the wood structure, extractives which vary in quantity and composition. PCA and 2D-COS made it possible to discriminate modifications in the wood samples according to treatment time and relative humidity. Non-extracted and water-extracted samples were also examined to identify the sequential order of band modification.


2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Lihe Ding ◽  
Lei-ming Yuan ◽  
Yiye Sun ◽  
Xia Zhang ◽  
Jianpeng Li ◽  
...  

Athletes usually take nutritional supplements and perform the specialized training to improve the performance of sport. A quick assessment of their athletic status will help to understand the current physical function of athletes’ status and the effect of nutritional supplementation. Human urine, as one of the most important body indicators, is composed of many metabolites, which can provide effective monitoring information for physical conditions. In this study, temperature-dependent near-infrared spectroscopy (NIRS) technology was used to collect the spectra of athlete’s urine for evaluating the feasibility of rapidly detecting the exercise state of the basketball player. To obtain the detection results accurately, several chemometrics methods including principal component analysis (PCA), variables selection method of variable importance in projection (VIP), continuous 1D wavelet transform (CWT), and partial least square-discriminant analysis (PLS-DA) were employed to develop a classifier to distinguish the physical status of athletes. The optimal classifying results were obtained by wavelet-PLS-DA classifier, whose average precision, sensitivity, and specificity are all above 0.95, and the overall accuracy of all samples is 0.97. These results demonstrate that temperature-dependent NIRS can be used to rapidly assess the physical function of athlete’s status and the effect of nutritional supplementation is feasible. It can be believed that temperature-dependent NIR spectroscopy will obtain applications more widely in the future.


2010 ◽  
Vol 61 (8) ◽  
pp. 1957-1963 ◽  
Author(s):  
Tetsuya Inagaki ◽  
Yukari Shinoda ◽  
Mitsuhiro Miyazawa ◽  
Hitoshi Takamura ◽  
Satoru Tsuchikawa

We examined the use of near infrared (NIR) spectroscopy as a rapid technique for the evaluation of sewage quality. Influent water samples, primary sedimentation tank water samples, and final effluent water samples were collected from sewage treatment facilities in Nagoya, Japan and their NIR spectra obtained. Partial least squares (PLS) models for total phosphate (TP), total nitrogen (TN), biochemical oxygen demand (BOD), total organic carbon (TOC), and turbidity of sewage water were constructed from the NIR data. The models provided good correlation between measurements obtained conventionally and those predicted from spectroscopy. Spectral variation induced by background interference in samples affected accuracy. Loading plots and score plots derived from PLS regression analysis resolved the background interference and allowed highly accurate predictions. Spectral variation induced by contamination in the sewage was a main predictor of sewage quality. These results show that NIR spectroscopy shows potential for in-line, non-destructive measurement of sewage quality.


Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 152 ◽  
Author(s):  
Paola Baltazar ◽  
Eva Cristina Correa ◽  
Belén Diezma

There is growing interest within the peach and nectarine markets in obtaining and selling ready-to-eat fruits. For this, pre-ripening protocols are being applied, which do not always result in sufficiently juicy fruits. Therefore, the aim of this study is the development of objective instrumental procedures for quantification of the juiciness attributes of these fruits. In this work, we evaluated the juiciness of more than 2000 fruits belonging to 20 of the varieties of greatest interest in the southeast of Spain. An instrumental mechanical procedure based on the confined compression of a pulp specimen of known volume was designed and optimized. Instrumental juiciness was defined as the wet area (cm2) on an absorbent paper located under the compression probe. This test allowed for the defining of objective thresholds for the identification of juicy fruits; 90% of the fruits with areas higher than 5.4 cm2 were considered to be juicy. Complementarily, non-invasive supervision by near-infrared (NIR) spectroscopy, based on pulp structural changes during ripening, allowed for estimation of the instrumental juiciness with coefficients of correlation above 0.83. The results of these instrumental procedures contribute to supporting decision tools in the logistics chain of stone fruits.


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